J tISSN 0892 lOlti) Journal OF Raptor Research V^OLL'ME 33 Marc;h 1999 Number I Contents Poisoning of Raptors with Organophosphorus and Carbamate Pesticides WITH Emphasis on Canada, U.S. and TJ.K. Pierre Mineau, Mark R. Fletcher, Linda C. Glaser, Nancy J. Thomas, Candace Brassard, Laurie K. Wilson, John E. Elliott, Linda A. Lyon, Charles J. Henny, Trent Bollinger and Stuart L. Porter 1 Expanded Abstracts Solving Raptor-Human Conflicts. Robert E. Kenward 38 Creating Raptor Benefits from Powerline Problems. Michael n. Kochert and Richard R. OlendorfF 39 Preventing Birds of Prey Problems at Transmission Lines in Western Europe. Patrick Bayle 43 Raptor Use and Abuse of Powerlines in Southern Africa. John a. Ledger and Jonathan C.A. Hobbs 49 Using a CIS to Integrate Seasonal Raptor Distributions into a Bird Avoidance Model for Aircraft. Michael m. Thompson 53 Seasonal Variation in Birdstrike Rate for Two North American Raptors: Turkey Vulture {Cathartes aura) and Red-tailed Hawk {Buteo jamaicensis) , T. Adam Kelly 59 Raptor Attacks on People, James w. Parker 63 The Extent, Cost and Control of Livestock Predation by Eagles with a Case Study on Black Eagles {Aquila verreauxii) in the Karoo. Robert a.g. Davies 67 Raptor Predation Problems and Solutions. Robert e. Kenward 73 Book Reviews. Edited by Jeffrey S. Marks 76 The Raptor Research Foundation, Inc. gratefully acknowledges a grant and logistical support provided by Boise State University to assist in the publication of the journal. THE JOURNAL OF RAPTOR RESEARCH A QUARTERLY PUBLICATION OF THE RAPTOR RESEARCH FOUNDATION, INC. VoL. 33 March 1999 No. 1 J. Raptor Res. 33(l):l-37 © 1999 The Raptor Research Foundation, Inc. POISONING OF RAPTORS WITH ORGANOPHOSPHORUS AND CARBAMATE PESTICIDES WITH EMPHASIS ON CANADA, U.S. AND U.K. Pierre Mineau Canadian Wildlife Service, Ottawa, Ontario KIA 0H3 Canada Mark R. Fletcher Central Science Laboratory, Central Science Laboratory, MAFF, Tangley Place, Worplesdon, Surrey GU3 3L() U.K. Linda C. Glaser and Nancy J. Thomas U.S. Geological Survey, National Wildlife Health Centre, 6006 Schroeder Road, Madison, WI 53711-6223 U.S.A. Candace Brassard U.S. Environmental Protection Agency, Office of Science Policy (8104R); 401 M Street, S.W., Washington, DC 20460 U.S.A. Laurie K. Wilson and John E. Elliott Canadian Wildlife Service, 5421 Robertson Road, RRl Delta, British Columbia V4K3N2 Canada Linda A. Lyon U.S. Fish and Wildlife Service, Division of Refuges, 4401 N. Fairfax Dr., Arlington, VA 22203 U.S.A. Charles J. Henny USGS Forest and Rangeland Ecosystem Science Center, 3200 5.W Jefferson Way, Corvallis, OR 97331 U.S.A. Trent Bollinger Canadian Cooperative Wildlife Health Centre, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N OWO Canada Stuart L. Porter Blue Ridge Community College, PO. Box 80, Weyers Cave, VA 24486 U.S.A. Abstract. — ^We reviewed cases of raptor mortality resulting from cholinesterase-inhibiting pesticides. We compiled records from the U.S., U.K. and Canada for the period 1985-95 (520 incidents) and surveyed the relevant literature to identify the main routes of exposure and those products that led to the greatest number of poisoning cases. A high proportion of cases in the U.K. resulted from abusive uses of pes- ticides (willful poisoning). The proportion was smaller in North America where problems with labeled uses of pesticides were as frequent as abuse cases. Poisoning resulting from labeled use was possible with a large number of granular pesticides and some seed treatments through secondary poisoning or through the ingestion of contaminated invertebrates, notably earthworms. With the more toxic products, residue levels in freshly-sprayed insects were high enough to cause mortality. The use of organophos- phorus products as avicides and for the topical treatment of livestock appeared to be common routes of intoxication. The use of insecticides in dormant oils also gave rise to exposure that can be lethal or 1 2 Mineau et al. VoL. 33, No. 1 which can debilitate birds and increase their vulnerability. A few pesticides of high toxicity were respon- sible for the bulk of poisoning cases. Based on limited information, raptors appeared to be more sen- sitive than other bird species to organophosphorus and carbamate pesticides. Some of the more signif- icant risk factors that resulted in raptor poisonings were: insectivory and vermivory; opportunistic taking of debilitated prey; scavenging, especially if the gastrointestinal tracts are consumed; presence in agri- cultural areas; perceived status as pest species; and flocking or other gregarious behavior at some part of their life cycle. Lethal or sublethal poisoning should always be considered in the diagnosis of dead or debilitated raptors even when another diagnosis (e.g., electrocution, car or building strike) is appar- ent. Many cases of poisoning are not currently diagnosed as such and, even when diagnosed, the infor- mation is often not made available to regulatory authorities. The importance of pesticide intoxications relative to other sources of mortality is highly variable in time and place; on a regional level, the increased mortality of raptors resulting from cholinesterase-inhibiting pesticides can be significant, es- pecially in the case of rare species. # Key Words: pesticides; anticholinesterases; poisoning, raptors; agriculture. Intoxicacion de los Rapaces con Pesticidas Organofosforico y Carbamate con Enfasi en Canada, Estados Unidos y el Reino Unido Resumen. — Examinamos los casos de mortalidad de los rapaces debido a los pesticidas colinasterase- inhibidores [cholinesterase-inhibiting] . Recopilamos documentos de los Estados Unidos, el Reino Unido y Canada por el periodo de 1985—95 (520 incidentes) y estudiamos la literatura referente a esto para identificar las rutas principales de la extension del riesgo al cual se exponen y examinar los productos que llevan a un gran numero de casos de intoxicacion. Un gran porcentaje de casos en el Reino Unido es el resultado del abuso en el uso de pesticidas (envenenamiento deliberado). La proporcion es mas pequena en America del Norte donde los problemas con usos descritos de pesticidas es tan frecuente como los casos de abuso. La intoxicacion que resulta del uso descrito es posible con un gran numero de pesticidas granulares y algunos tratamientos de semilla mediante envenenamiento secundario o por medio de la ingestion de invertebrados contaminados, en forma notable las lombrices. Con los prod- uctos mas toxicos, el nivel de residue en los insectos recien rociados es suficientemente alto para causar la mortalidad. El uso de los productos organofosfatos como avicidas y para el tratamiento corriente del ganado parece ser la ruta comun de intoxicacion. El uso de insecticidas en el aceite mineral insecticida, tambien aumenta la extension de riesgo al que estan expuestos que puede ser mortal o que puede debilitar a los pharos e incrementar su vulnerabilidad. Algunos pesticidas del alta toxicidad son res- ponsables por el volumen de casos de envenenamiento. En base a la informacion limitada, parece ser que los rapaces son mas sensibles que otras especies de aves a los pesticidas organofosforicos y carbamate [carbamate]. Algunos de los factores de riesgo mas significativos que causa la intoxicacion en los rapaces son el hecho de ser insectivoros y vermivoros; la toma oportunista de la presa debilitada; la alimentacion de carrona, especialmente si la region gastrointestinal esta consumida; la presencia en areas agricolas; la condicion percibida como especies de plaga; y la congregacion en bandada u otra conducta gregaria en alguna parte de su ciclo de vida. La intoxicacion mortal o submortal debe considerarse siempre en el diagnostico de los rapaces muertos o debilitados, aun cuando se manifieste otro diagnostico (ej. electrocucion, golpearse o estrellarse contra un carro o edificio). Muchos casos de envenenamiento actualmente no se diagnostican como tales y, aun cuando son diagnosticados, a menudo la informacion no esta disponible a las autoridades reguladoras. La importancia de las intoxicaciones de pesticidas relativa a otras fuentes de mortalidad es altamente variable en tiempo y lugar; a nivel regional, la mortalidad aumentada de rapaces causada por los pesticidas colinaestarase-inhibidores puede ser sig- nificativa, especialmente en el caso de las especies poco comunes. [Traduccion de Anne Grondin y Marguerita Merino] The link between declines of some raptor pop- ulations and organochlorine insecticide (OC) con- tamination has been well established. OC contam- ination is still of concern in many parts of the world because of their continuing use and heavy contamination from prior use. In most developed countries, the more acutely toxic and/ or bioaccu- mulating OCs were replaced by the shorter-lived but acutely toxic cholinesterase (ChE) -inhibiting organophosphorus (OP) and carbamate (CB) pes- March 1999 Pesticide Poisoning of Raptors 3 ticides. Despite advances in pest control and the introduction of more targeted products, ChE in- hibitors are still ubiquitous. Because of their acute toxicity, OP and CB compounds are frequently im- plicated in abuse cases where raptors or other ver- tebrates are targeted directly; however, there is an increasing number of reports of poisonings caused by labeled uses of these products. Some kills can be very large, such as the recent loss of several thousand Swainson’s Hawks (Buteo swainsoni) (see Appendix 1 for Latin names; nomenclature follows del Hoyo et al. [1994]) in Argentina (Woodbridge et al. 1995, Goldstein et al. 1996, Goldstein 1997, Canavelli and Zaccagnini 1996). Based on a review of both published and unpublished cases, we eval- uated those factors responsible for the kills, namely the toxicity of registered products and the extent to which their formulation enhanced exposure, as well as the dietary and social habits of raptors and their use of agricultural habitats for foraging. While we emphasized incidents reported from Canada, U.S. and U.K. during 1985-95, our intent was to provide a comprehensive review of known poisoning cases. Our objective was to go beyond descriptions of mortality to establish a commonal- ity among incidents and to identify the main fac- tors responsible with a view toward mitigation. Why Raptors? Many bird species are known to be killed rou- tinely by ChE-inhibiting pesticides. In what was the first review of such poisonings in North America, Grue et al. (1983) listed 52 species from 15 bird families being killed in 30 documented incidents between 1965-83. A review of wildlife incidents oc- curring in England and Wales between 1964-83 also reported several cases of poisoning with anti- cholinesterase pesticides in a broad range of spe- cies (Hardy et al. 1986). Our review is restricted to raptorial species as well as to both Old and New World vultures (e.g., Accipitridae, Falconidae, Ga- thartidae and Strigidae). From an ecological per- spective, these birds are generally long-lived and have deferred maturity. From a pragmatic point of view, several raptor species may be useful as senti- nels in agricultural habitats. For example, scaveng- ing species such as the Bald Eagle {Haliaeetus leu- cocephalus) are much more likely to detect primary pesticide kills than human observers (Elliott et al. 1996, Elliott et al. 1997). Methods The main sources of information for this review were incidents involving raptors reported to authorities in Canada, U.S. and U.K. Complete lists of cases occurring between 1985-95 were obtained from the Canadian Wild- life Service and Canadian Cooperative Wildlife Health Centers (CCWHC), and from the records held by the Central Science Laboratory for the U.K. Cases from 1985-94 in the U.S. were compiled from records held by the U.S. Fish and Wildlife Service (USFWS), Environ- mental Protection Agency (USEPA) and Biological Re- sources Division of the U.S. Geological Survey (USGS) at the National Wildlife Health Center. Some of the North American incidents were already tallied by state (Thomas and Franson 1993, Glaser 1994, Franson et al. 1995) but, with few exceptions (e.g., some owls [Blus 1996]), they have not been otherwise published or analyzed. All of the U.K. incidents have been published on a yearly basis (Fletcher and Hardy 1986, Fletcher et al. 1989, Fletcher et al. 1990, Fletcher et al. 1991, Fletcher and Hunter 1993, Fletcher et al. 1994, Fletcher et al. 1995, Fletcher et al. 1996, Fletcher et al. 1997). Some of the Canadian incidents have already been described (Elliott et al. 1996, Elliott et al. 1997) or summarized in newsletters of the CCWHC. Others have been tabulated (Wilson et al. 1995) but not otherwise described. We ascribed a ‘certainty index’ to each incident de- noting the amount of information available. We recog- nized the following categories: (1) identified chemical residues in tissues, gut contents or bait material and ChE evidence; (2) identified chemical residues and circum- stances clearly indicative of poisoning (e.g., cases of mass mortality, signs, likely route of exposure and source of pesticide identified); (3) ChE evidence and circum- stances clearly indicative of poisoning but chemical resi- dues nondetectable or not analyzed; (4) ChE evidence only with no ancillary information, residues nondetecta- ble or not analyzed (in this category, the nature of the ChE evidence was key to the significance attached to the incident; ChE evidence can be at levels very much below normal, reactivation data or serially obtained measure- ments for live birds only showing recovery with time); (5) circumstances clearly indicative of poisoning such as re- ports of mass mortality following specific pesticide use but no chemical or biochemical data available; often clin- ical signs are consistent with poisoning and other likely causes of death (e.g., pathogens, electrocution and shoot- ing) have been eliminated; here, negative chemical anal- ysis and/or ChE data would likely make us discard the incident. We used details supplied with the incident record such as any forensic data (e.g., the nature of gut contents) to ascribe a probable cause. For example, we categorized any Canadian or U.S. incident report mentioning that coyotes ( Cams latrans) , wolves ( Canis lupus) or large num- bers of raccoons {Procyon lotor) were also found dead along with the raptors as an abuse case. For this review, we used best scientific judgment to categorize incidents We recognize that, in several cases, the information avail- able might be judged inadequate by legal standards. We also had to exercise scientific judgment in deciding what constituted a single incident. Coincidence of time and place and the identity of the residues obviously weighed 4 Mineau et al. VoL. 33, No. 1 strongly in this decision. With few exceptions (Stinson et al. 1994) the incidents did not result from specific re- search or monitoring exercises associated with a specific pesticide treatment. Kills recorded in the course of in- dustry-sponsored field studies (e.g., Booth et al. 1986) were not included in the tallies, but are reviewed in the discussion where appropriate. We did this to avoid intro- ducing another bias in the record given that not all pes- ticides have had the same degree of scrutiny. We extend- ed the time period backwards or forward to capture other incidents when these offered useful insights. The dates 1985-95 corresponded with a general increase (in North America at least) in the effort made to document raptor mortality following poisoning with anticholinester- ase compounds. We were able to find only 1 1 records of raptors being poisoned by ChE-inhibiting pesticides be- fore that period. Mendelssohn and Paz (1977) reported that ChE poisonings were not well documented but, after their work on the OP famphur, Henny et al. (1985) sug- gested that the lack of OP secondary poisoning reports for birds of prey in North America might be due to the limited number of dead raptors being analyzed for ChE depression and OP residues. At about that time, the US- EPA was engaging in reviews of the insecticides diazinon and carbofuran because of documented wildlife mortal- ity This resulted in a general increase in the reporting of wildlife kills. In the U.K., a wildlife incident scheme with more con- stant reporting effort has been in operation for more than 30 yr (Hardy et al. 1986, Greig-Smith 1991). The choice of the period 1985-95 was purely arbitrary. Biases Inherent in a Passive Incident Scheme Most of the information reported here originat- ed from reported cases of mortality and, as such, was subject to many biases and limitations. First of all, it was very difficult to assess what proportion of incidents were reported to national authorities and were therefore available for tabulation and analysis. For example, on the basis of personal communications from local authorities and reha- bilitation centers. Fry et al. (1998) accounted for 34 Red-tailed Hawks {Buteo jamaicensis) poisoned by OP insecticides mixed in dormant oil sprays in California almond orchards between 1987-90; 18 hawks died and 16 were treated with atropine and released. Hooper et al. (1989) working on a subset of those birds described two parathion-poisoned hawks as well as four more hawks brought to re- habilitation centers with depressed plasma ChE, symptoms of poisoning and mixed OP residues on their feet. Furthermore, eight of 12 wild-caught birds in orchards exhibited reduced ChE levels al- though only one showed signs of poisoning. Only the two parathion-poisoned birds (<6% of known cases) appeared in the combined data bases of the USEPA and USGS for the same time period. Con- tacting every competent state and local authority was beyond the scope of this review. Therefore, we used only a limited subset of documented inci- dents, at least in the U.S. We did not know whether these cases were a representative subset. Since then, the USEPA increased its efforts to collect in- cident information from competent authorities (Anonymous 1994). The proportion of document- ed incidents over all incidents was even more dif- ficult to estimate. Secondly, the information available on each in- cident was of uneven quality and there were often many unknowns. Numbers of birds reported should be treated as minima. For example, in a few cases, the plural form (e.g., eagles) was the only indication as to the number of birds involved. Two individuals were ascribed to such incidents and “several birds” was taken to mean at least three. There were systematic biases associated with in- cident reporting. In the U.S., cases involving Bald and Golden Eagles {Aquila chrysaetos) were more likely to be investigated fully because these species have federal protection. Also, because of regula- tory initiatives such as Special Reviews (re-evalua- tions of specific pesticides and specific use patterns in response to a perceived problem) initiated by the USEPA, there has been a more intensive focus on some products; for example, the insecticides diazinon and carbofuran. Large-bodied birds or flocking birds have a higher probability of being discovered (Baillie 1993). Because of delays in re- porting, as well as frequent omission of critical data, causality for many raptor incidents can be dif- ficult to establish. Having access to all the infor- mation surrounding any given incident is particu- larly relevant in trying to distinguish malicious poisoning of birds and other gross pesticide label violations from incidents resulting from normal ag- ricultural practice. The distinction is important be- cause the solutions are different. In the first case, education and legal enforcement of existing stat- utes can solve abuses of pesticides and, in the sec- ond case, changes in agronomic uses and regula- tory changes to registered pesticide use patterns are needed to solve problems arising from labeled uses. Pesticide misuse is also a recognized problem although the term has been used so loosely that its significance is often unclear. Also, the word misuse has been used in North America to mean malicious intent in much the same context as abuse in Eu- ropean terminology (Fletcher et al. 1996). The simplest definition of misuse is unintentional fail- March 1999 Pesticide Poisoning of Raptors 5 ure to follow label instructions. However, a misuse in one jurisdiction may indeed be a registered use in the next. Also, a certain degree of flexibility in label interpretation is allowed under most national pesticide legislation. In the case of Swainson’s Hawk mortality in Argentina, the insecticide mon- ocrotophos, although not specifically labeled for grasshopper control, was officially tolerated and even promoted for that use because no generally- recognized interdiction existed and because the pesticide was registered for other pest species at the same rates and on the same crops (Mineau 1996). In some cases, misuse was reported because rates applied were too high or the products ap- plied poorly (e.g., some granular insecticides pre- sent on the soil surface rather than buried) . How- ever, it has been repeatedly demonstrated that the ability of farmers and pesticide applicators to fol- low labels exactly is highly variable under real-life conditions (Rider and Dickey 1982, Ellis 1982, Thompson et al. 1985). Even under carefully cali- brated and monitored conditions, pesticide appli- cations are highly variable (Maze et al. 1991). Fi- nally, it has been argued (Mineau 1993) that some labels are simply untenable. For example, any ap- plication of carbofuran in Canada should be con- sidered a misuse because the label clearly states that it should be kept out of areas inhabited by fish, birds and wildlife because it is highly toxic to such animals. Implicit in this label statement is the (mistaken) assumption that birds and other wild- life species do not frequent agricultural fields. In this review, we did not describe any incidents as cases of misuse. Instead, based upon the apparent severity of the infraction, we ascribed them either to abuse or to labeled use. Cases where interpre- tation was difficult were discussed in the text or alternatively, we simply left them as “use un- known.” For several reasons, cases of pesticide abuse are more likely to be reported than other cases or, at least, to be recognized as such. These cases fre- quently result from the use of highly concentrated baits, and birds often do not go far from the site of intoxication (Greig-Smith 1987a). Birds which fly away from the site of exposure are unlikely to be analyzed for exposure to ChE-inhibiting pesti- cides. For example, in response to a request for carcasses, the Institute of Terrestrial Ecology in Britain received 276 Eurasian Sparrowhawks {Accip- iter nisus) and 56 Common Kestrels {Falco tinnun- culus) between 1987-90 (Newton et al. 1992). Those carcasses were analyzed for OC residues, but not for ChE-inhibiting pesticides. During that same period, the pesticide incident scheme reported that one sparrowhawk (out of 22 received) and one kestrel (out of 28 received) had tested positive for ChE inhibitors. The pesticide incident scheme in the U.K. collects birds primarily associated with agricultural operations. Therefore, even where there were good working schemes for investigating field kills, it was unlikely that individuals that were found on roads or near habitations were tested routinely for currently used pesticides. In the lower Fraser estuary of British Columbia, Canada, most reported raptor mortality was from overnight roost sites in urban and suburban parks. Given the na- ture of residues detected, it appeared the birds were poisoned in the course of their day-time for- aging trips into agricultural fields, but most were able to fly to their night roosts before succumbing. It was not until a systematic effort to recover and analyze carcasses and moribund individuals from rehabilitation centers began in 1990 that the inci- dents were documented as pesticide-related. Also, the investigation of abuse is often pursued more vigorously and carefully because of legal im- peratives; unfortunately, information pertaining to these incidents may be withheld for legal reasons resulting in fragmentary data being made available for a period of a few years after the incident. An- other factor which favored the reporting of abuse cases over labeled ones was that abuses are consid- ered less sensitive in that they do not reflect poorly on a jurisdiction’s agricultural operations or pesti- cide regulatory system. Also, pesticide users may be reluctant to report problems stemming from la- beled uses if they believe the pesticide implicated is essential to their livelihood. Results and Discussion A total of 255, 102 and 63 incidents were re- ported for raptors over the period 1985-95 (Table 1 ) . Of these, most were either given certainty in- dices of 1 or 2 (Fig. 1). Incidents were further tal- lied either by the chemical and type of incident involved (Tables 2, 3, 4) or by the species killed (Tables 5, 6, 7). Abuse vs. Labeled Use of Pesticides. The extent to which incidents result from pesticide abuse as opposed to approved uses is usually the first ques- tion asked by any pesticide incident reporting sys- tem. In the U.K., the criminal abuse of pesticides for killing birds of prey has long been acknowl- 6 Mineau et al. VoL. 33, No. 1 Table 1. Yearly tally of U.S., U.K. and Canadian raptor mortality incidents involving pesticides from 1985-95. ytAR U.S. U.K. Canada No. Incidents Minimum No. Birds No. Incidents Minimum No. Birds No. Incidents Minimum No. Birds 1985 13 20 10 13 — — 1986 21 32 16 19 — — 1987 23 47 3 3 — — 1988 33 74 4 5 — — 1989 26 93 16 23 — — 1990 23 46 1 1 9 13 1991 29 168 6 11 2 2 1992 33 85 8 10 11 27 1993 24 88 11 15 8 37 1994 31 82 13 14 17 18 1995 N/A N/A 14 21 16 25 Total 255 734 102 136 63 122 edged and is of conservation concern (Brown et al. 1977, Cadbury 1980, Elliott and Avery 1991). In addition to birds of prey, corvids and several wild and domestic manunal species are also targeted by applications and raptors killed inadvertently. These kills are usually related to gamebird retiring, lamb production and attempts to protect racing pigeons. In the U.K., yearly proportions of incidents as- cribed to deliberate abuse of pesticides relative to the total munber of incidents reported involving agricultural pesticides with all bird and mammal species ranged from 65-82% (median = 71%) of 64^127 incidents per year (Greig-Smith 1988). The proportion of abuses z^ainst raptors over the 1985-94 period was 87% (Table 3). There was probably a slight overrepresentation of abuse cases because only incidents with certainty indices of 1 and 2 were tabulated. Often, the diz^osis of abuse was made on the basis that there was no longer an approved registration for the given pesticide and it did not always result from an intent to kill raptors or other vertebrates. For example, fenthion does not have an approved use as a treatment for ecto- parasites in sheep although it was approved for the 1 2 3 4 5 Certainty index Figure 1. Certainty index for incidents tabulated in this review. 1 — identified residues in tissues, gut contents or bait material and Ch£ evidence. 2 — ^identified residues and circumstances clearly indicative of poisoning. 3 — ChE evidence and circumstances clearly indicative of pK>isoning. 4 — ChE evidence. 5 — circumstances clearly indicative of poisoning. March 1999 Pesticide Poisoning of Raptors 7 Table 2. Summary of pesticides implicated in U.S. raptor kills (1985-94) according to whether they were thought to have resulted from labeled use, abuse, spill or where the use pattern was unknown. No. Incidents Labeled Use Abuse Spill Unknown Use Total Minimum N o. Birds Pesticide aldicarb — 4 — 3 7 12 carbofuran 25 55 — 36 116 406 chlorpyrifos 3 — 1 — 4 4 coumaphos — — — 1 1 1 diazinon — — — 2 2 2 dicrotophos — — — 1 1 2 disulfoton 1 — — — 1 21 famphur 6 8 — 37 51 68 fenthion 18 1 — 10 30 72 parathion 2 — — 5 7 26 phorate 2 2 1 2 7 15 phosphamidon — 1 — — 1 3 terbufos — — — 3 3 12 unknown — — — 17 17 22 Mixtures carbofuran and methomyl — 1 — — 1 3 chlorpyrifos and diazinon 4 — — — 4 4 chlorpyrifos and fonofos — 1 — — 1 59 chlorpyrifos, diazinon and meth- idathion 2 — — — 2 2 Totals 63 73 2 117 255 734 Table 3. Summary of pesticides implicated in U.K. raptor kills (1985-95) according to whether they to have resulted from labeled use, abuse, spill or where the use pattern was unknown. were thought No. Incidents Labeled Use Abuse Unknown Spill Use Total Minimum No. Birds Pesticide aldicarb — 1 1 2 bendiocarb — 2 — 1 3 6 carbofuran 3 10 — 1 14 20 diazinon — — — 2 2 2 disulfoton — 1 — — 1 1 famphur 1 — — — 1 2 fenthion — 26 — — 26 36 malathion — 5 — 1 6 7 mevinphos — 44 — — 44 56 phorate 1 1 — — 2 2 phosmet — 1 — — 1 1 propetamphos — — — 1 1 1 Totals 5 89 — 7 102 136 8 Mineau et al. VoL. 33, No. 1 Table 4. Summary of pesticides implicated in Canadian raptor kills (1985-95) according to whether they are thought to have been the results of labeled use, abuse, spill or where the use pattern was unknown. No. Incidents Labeled Use Abuse Unknown Spill Use Total Minimum N o. Birds Pesticide azinphos methyl — ■ — — 3 3 3 carbofuran 3 6 — — 9 28 fensulfothion 1 — — — 1 3 fenthion — 1 — 1 2 3 fonophos 8 — — — 8 9 parathion — — — 4 4 4 phorate 3 2 — — 5 34 terbufos 3 — — — 3 3 unknown OP — — — 4 4 4 unknown CB — 1 — 1 2 3 unknown OP or CB — 1 — 16 17 18 Mixtures carbofuran and terbufos — 1 — — 1 4 phorate and ethion 1 — — — 1 1 phorate and methamidophos 2 — — — 2 4 terbufos and pirimicarb 1 — — — 1 1 Totals 22 12 — 29 63 122 treatment of warble fly in cattle until June 1994 and may have been used historically to treat sheep. Therefore, any presence of lamb’s wool and fen- thion in a British raptor automatically precipitated a diagnosis of abuse whether fenthion was used with the willful intention of killing raptors or whether it represented an unregistered attempt to kill ectoparasites in sheep. Nevertheless, the fre- quent presence of bait material as well as the fre- quent use of products clearly not labeled for crops grown in the area where most of the incidents oc- curred (e.g., the case for most mevinphos inci- dents) did indicate that most raptor incidents in the U.K. were the result of deliberate abuse. Spi- erenburg et al. (1990) reached a similar conclu- sion in the Netherlands following a review of 143 poisoning incidents occurring between 1975—88. In France, Berny (pers. comm.) also identified abuse as a major cause of incidents following a re- view of approximately 150 poisoning incidents in- vestigated between 1991-96. Although most cases of deliberate abuse resulted from attempts to kill wildlife regarded as pests, the use of pesticides in poaching wildlife for human consumption may also be endemic in some areas. In some cases, game birds are targeted and raptors are sec- ondarily poisoned and, in others, raptors are tar- geted directly. For example, both situations have been recorded in South Africa where vultures were sought after as a source of traditional medicine (van Jaarsveld 1987, Fourie et al. 1996, Verdoorn in press) . The poisoning of ponds and waterholes with pesticides is used to harvest game species in Southeast Asia (Thiollay pers. comm.). In contrast, pesticide abuse is thought to be less prevalent in North America. In his review of U.S. poisoning incidents, Grue et al. (1983) document- ed five cases of abuse relative to 26 cases of unin- tentional poisoning with OP pesticides. No raptors were found in any of these incidents. We estimated that, between 1985-94, there were 73 reported abuse cases relative to 64 labeled-use incidents for raptors specifically (Table 2). In Canada, labeled cases outnumbered abuse cases by a 2:1 ratio. In fact, circumstances surrounding most of the cases in the unknown category were highly suggestive of labeled use. Where ChE inhibitors were con- cerned, raptors in North America were at least as likely to be killed from a labeled pesticide use than from a willful attempt to poison them or some oth- er vertebrate. One of our goals was to explore the apparent discrepancy between North America and March 1999 Pesticide Poisoning oe Raptors 9 Table 5. Breakdown of U.S. cases involving the deaths of raptors from pesticides. Species Number of Individuals Labeled Uses Abuses Use Unknown Spills Total Turkey Vulture — 8 2 1 11 Black Vulture — 61 — — 61 Osprey — — 2 — 2 White-tailed Kite 1 — — — 1 Mississippi Kite 17 — — — 17 Bald Eagle 31 87 125 — 243 Hen (Northern) Harrier 7 6 1 — 14 Sharp-shinned Hawk 2 — — — 2 Cooper’s Hawk 9 — 3 — 12 Red-shouldered Hawk — — 2 — 2 Swainson’s Hawk 20 — — — 20 Ferruginous Hawk — 3 — — 3 Rough-legged Hawk 1 — — — 1 Red-tailed Hawk 57 47 29 — 133 Golden Eagle — 125 19 — 144 Unidentified hawk 0 8 — 1 9 American Kestrel 3 — 1 — 4 Prairie Falcon — 1 — — 1 Peregrine Falcon 5 — 1 — 6 Barn Owl — — 1 1 2 Short-eared Owl 1 — — — 1 Great Horned Owl 8 5 5 — 18 Barred Owl 4 — 1 — 5 Snowy Owl 2 — 1 — 3 Eastern Screech Owl 3 — 1 — 4 Unidentified owl 10 5 — — 15 Totals 181 356 194 3 736 Table 6. Breakdown of Canadian cases inv olving the deaths of raptors from pesticides. Number of Individuals Species Labeled Uses Abuses Use Unknown Spills Total Bald Eagle 47 17 — — 64 Hen (Northern) Harrier 30 — — — 30 Red-tailed Hawk 12 12 — — 24 Golden Eagle — 4 — — 4 Rough-legged Hawk 1 — — — 1 Peregrine Falcon 1 — — — 1 Snowy Owl 1 — - — — 1 Unidentified owl — — 1 — 1 Totals 92 33 1 0 126 10 Mineau et al. VoL. 33, No. 1 Table 7. Breakdown of U.K. cases involving the deaths of raptors from pesticides. Species Number of Individuals Labeled Uses Abuses Use Unknown Spills Total Red Kite 1 23 5 — 29 Marsh Harrier — 3 — — 3 Hen Harrier — 1 — — 1 Sparrowhawk — 5 — — 5 Buzzard 4 64 3 — 71 Golden Eagle — 5 — — 5 Common Kestrel — 4 — — 4 Peregrine Falcon — 12 2 — 14 Little Owl 2 — — — 2 Tawny Owl — 2 — — 2 Totals 7 119 10 — 136 Europe in order to better understand why poison- ings occur. Of course, both in North America and Europe, pesticides and chemicals other than ChE inhibitors have been used in abuse cases. These include strychnine, thallium sulfate, alpha-chloral- ose, cyanide and sodium fluoroacetate (Com- pound 1080). Not all species were as likely to suffer the brunt of pesticide abuse. The high vulnerability of the Common Buzzard {Buteo buteo) in Britain has al- ready been reviewed (Brown et al. 1977, Cadbury 1980, Elliott and Avery 1991) . Our review indicated that this species continued to be targeted. In the Netherlands, Red Kites {Milvus milvus) had the most frequent diagnosis of poisoning (as a propor- tion of reported incidents for each species), al- though more Common Buzzards and Goshawks {Accipiter gentilis) were found poisoned (Spieren- burg et al. 1990). Unfortunately, that source did not provide the proportion of abuse cases by spe- cies. In North America, the Golden Eagle ap- peared to be almost always killed by abuse (Tables 5, 6). This is likely because Golden Eagle habitat seldom overlaps with cropland. Most kills were recorded in the western U.S. in association with attempts to kill eagles and/or coyotes. Allen et al. (1996) described how a liquid formulation of car- bofuran applied on sheep carcasses to kill coyotes persisted for at least two months at high enough concentration to kill Bald Eagles that fed directly on the sheep as well as a Red-tailed Hawk which fed on a European Starling {Sturnus vulgaris) which also became contaminated after contact with the sheep meat. The Red-tailed Hawk was one of several species equally likely to be recorded follow- ing an abuse case or labeled use. Many other spe- cies, especially those that are less prone to scav- enging and therefore to taking baits, were more frequently encountered in cases involving labeled uses. This was most notable for accipiters and most owl, falcon and kite species. Pesticides employed in abuse cases undoubtedly reflected availability as well as toxicity to the in- tended victim. Carbofuran was widely available in several formulations and registered for a large number of crops. This single pesticide accounted for 75% of all known OP and CB abuse cases in the U.S. and 50% of Canadian cases (Tables 2, 4). In the U.K., mevinphos and fenthion accounted for more than 80% of abuse cases over the S2ime period (Table 3) . Older abuse incidents where the intent was to control songbirds often involved para- thion-treated seed, both in North America (Stone et al. 1984) and Europe (Smit et al. 1986). The virtual absence of parathion from the more recent record probably reflected its reduced use. There was evidence that, where registered, monocroto- phos was a popular bird control chemical. This was the case in South Africa (Fourie et al. 1996). A recent (1997) use of monocrotophos baits in Ar- gentina killed an estimated 63 000 doves in cereal fields (Zaccagnini pers. comm.). Most of the birds killed were Eared Doves {Zenaida auriculata) with other dove and small granivorous bird species. Fif- teen Barn Owls {Tyto alba) were also found dead in that incident. Main Routes of Exposure for Raptors from La- beled Use. Consumption of Contaminated Inver- March 1999 Pesticide Poisoning oe Raptors 11 tebrates. Many species of raptors were killed through the consumption of contaminated inver- tebrates. Insectivory is important to many raptor species. Of the 237 accipitrids recognized world- wide, 56 (24%) are exclusively or largely insectiv- orous whereas another 100 species (42%) are oc- casionally insectivorous (del Hoyo et al. 1994). There are numerous examples of species from the Northern Hemisphere which specialize on insects on the wintering grounds. European species such as Black Kites (Milvus migrans) feed on locusts in the Sahel or southern Africa and North American Swainson’s Hawks that historically fed on locusts now eat grasshoppers and other insect species in the Argentine pampas. Because most OP and CB compounds are used as insecticides, consumption of contaminated insects is an important risk factor to consider for many species. The Swainson’s Hawk may have been particularly vulnerable because of its apparent specialization on pests during out- breaks in agricultural crops. Incidents occurred not only in association with grasshopper control, but also in cotton and corn (maize) fields. In a cornfield, a kill was reported when they were con- suming beetle larvae. They have also been report- ed to dive into mature corn to take caterpillars (Woodbridge pers. comm.). Consumption of Freshly-sprayed Insects. The most ob- vious exposure situation was where freshly-sprayed insects are consumed directly by raptors. Large numbers of Swainson’s Hawks died following grass- hopper control in Argentina (Woodbridge et al. 1995). During the 1995-96 austral summer, as many as 3000 birds were killed in a single incident and at least 18 different incidents were witnessed for a total of about 5000 birds (Canavelli and Zac- cagnini 1996). Based on an extrapolation of the area searched for kills and assuming all kills were located (an unlikely assumption which provides for a very conservative estimate) , it was estimated that the 1995-96 mortality exceeded 5% of the total population of this species or more than 20000 birds, largely because of the use of the organo- phosphate insecticide monocrotophos (Goldstein et al. 1996, Goldstein 1997). One incident was also thought to be caused by dimethoate but it could not be confirmed chemically. A smaller number of kills resulting from monocrotophos use continued to be reported in the 1996-97 and 1997-98 austral summers (Zaccagnini pers. comm.). Franson (1994) documented 16-18 Mississippi Kites (Ictinia mississippiensis) that died following the ingestion of caterpillars taken from a cotton field sprayed with parathion. The kill was reported because the birds died on a nearby golf course pointing out the chance element in any bird kill being uncovered. Fox et al. (1989) documented the disappearance of Burrowing Owls {Athene cunicularia) following spray applications of carbofuran (but not carbaryl, a grasshopper insecticide of lower acute toxicity) for grasshopper control. However, it was not deter- mined whether exposure was through consump- tion of treated grasshoppers (the most likely hy- pothesis) or small mammals, another possible food source. Unfortunately, no carcasses were recovered for analysis. It was noteworthy that the rate of ap- plication of carbofuran implicated in the owl’s dis- appearance was one of the lowest rates registered anywhere in the world (132 g.a.i./ha). Insecticides used for grasshopper spraying must be of low acute toxicity because of the importance of this food source for a large number of bird species including raptors. Consumption of Invertebrates Contaminated by Gran- ular Insecticides or Seed Treatments. Granular insecti- cides are extremely concentrated sources of insec- ticides. Granular products are a known problem when ingested by birds when perhaps they mistake them for grit or for a novel food source. The gran- ular insecticide carbofuran has also been ingested by raptors such as Red-shouldered Hawks {Buteo lineatus) when the granules accidentally adhered to earthworms (Balcomb 1983). Even when granules were washed away, substantial residue levels re- mained. Only a few U.S. incidents clearly resulted from the direct ingestion of invertebrates contam- inated by pesticide formulations other than sprays. In one incident in Texas in 1996 (data submitted by the manufacturer to the USEPA through man- datory adverse effect reporting regulations), 20 Swainson’s Hawks were poisoned after ingesting grubs of the southern masked chafer ( Cyclocephala lurida) contaminated with a granular formulation of terbufos (Counter 15G) used on seed corn. The birds picked up insects brought to the surface by high soil moisture and planting operations. High moisture conditions resulted in poor furrow clo- sure. Granules were probably ingested directly from the soil because grubs were not found in the gastrointestinal tracts of the birds. In another in- cident in Texas in 1993, 20 Swainson’s Hawks were found poisoned (19 died, one was rehabilitated and released) after feeding on an insect pest of cotton seedlings. The cotton seed had been treated 12 Mineau et al. VoL. 33, No. 1 at the sales outlet with the OP disulfoton and the seedlings were approximately 10-13 cm in height when the incident occurred (Hamilton pers. comm.). To our knowledge, this is the only docu- mented case where a systemic insecticide passed through crop plants to grazing insects in sufficient quantity to then kill birds. In the U.K., few kills resulted from labeled pes- ticide use, but three of four incidents clearly asso- ciated with labeled use were caused by granular carbofuran (Table 3) and two of the three involved earthworm ingestion and Common Buzzards. Sev- eral kills of earthworm-feeding Common Buzzards were also documented in Switzerland following the use of carbofuran in sugar beet fields; both Black and Red Kites are thought to have been similarly poisoned (Dietrich et al. 1995). The risk to birds may be higher for CBs like carbofuran because this class of insecticides is particularly toxic to earth- worms. Earthworms exposed to CB products exhib- it violent coiling behavior at the soil surface which is likely to attract predators. Because of their reli- ance on earthworms, buzzards and kites are likely to be affected more broadly in Europe. For ex- ample, Berny (1993) documented kite poisoning through earthworm consumption in France. Secondary Poisoning Through Consumption of Vertebrates. In its strictest definition, secondary poisoning is the passing of residues assimilated into one animal tissue into another animal. This was the standard way in which lipophilic OC insec- ticides accumulated in food chains. The USEPA re- fers to secondary poisoning as residues being passed from vertebrate to vertebrate without re- gard to the exact location of these residues (Urban and Cook 1986). This is the most practical defini- tion and the one we used. It is likely that most cases of ‘secondary poisoning’ involving OP and CB pes- ticides do not involve residues assimilated in the tissues of the primary kill. In most cases, residues are transferred to predators or scavengers when the gut contents are ingested or when surface (e.g., feather or foot) residues are ingested or trans- ferred during prey handling. However, Hill and Mendenhall (1980) showed that sufficient quanti- ties of the OP famphur could pass from the gut to post-absorptive tissues in dosed quail to induce both plasma and brain ChE inhibition in Barn Owls. For many raptor species, carrion represents most of their total food intake, at least during some por- tions of the year. For European raptors, these in- clude Common Buzzards, Red Kites and Golden Eagles (Barton and Houston 1994a). Raptors need not scavenge to be exposed to contaminated prey. Hunt et al. (1991) found that House Sparrows {Passer domesticus) exposed to lethal doses of fen- thion through their feet were mobile for up to four hours postexposure and, as the birds became grad- ually incapacitated over that period, they were 16 times more likely to be captured by American Kes- trels {Falco sparverius) than their uncontaminated flock mates (Hunt et al. 1992). Information on whether raptors eviscerate their prey in the wild is difficult to obtain, yet this is one of the most critical risk factors affecting the likeli- hood of secondary poisoning from ChE-inhibiting pesticides. Fat is the most energetically-valuable tis- sue in a carcass (Barton and Houston 1994b). Rap- tors are therefore likely to seek mesenteric fat at- tached to the gastrointestinal tract. On the other hand, it may be energetically inefficient to ingest large quantities of green forage contained in the gastrointestinal tracts of prey. Burrowing Owls evis- cerated ground squirrels before consuming them (James et al. 1990) which greatly reduced their risk of secondary poisoning from strychnine baits. De- spite the many waterfowl kills recorded from dia- zinon use on turf (Stone and Gradoni 1985, Frank et al. 1991), we were unable to find any documen- tation of secondary poisoning associated with those kills. However, this may also have been a function of the habitat and a paucity of scavengers associ- ated with turfed areas. Under different circum- stances, consumption of waterfowl gut contents represents a common route via which granular in- secticides are passed on to scavengers. Hiraldo et al. (1991) described Red Kites, Hen Harriers {Cir- cus cyaneus), Imperial Eagles {Aquila heliaca) and Common Buzzards, as well as several vulture spe- cies at goose carcasses in Spain. They ate muscle as well as viscera, but no mention was made of how the gut contents were handled. Granular insecticides. The most common form of secondary poisoning in raptors was seen following the use of granular insecticides. Granular insecti- cides are highly concentrated forms of pesticides (generally 5-20% insecticide by weight) which are often implicated in killing songbirds, shorebirds and waterfowl, as well as small mammals. Kills are characterized by a slug of concentrated granular material generally found in the gastrointestinal tract of the primary kill. Granular insecticides are particularly attractive to songbirds, either as grit or March 1999 Pesticide Poisoning of Raptors 13 as food, and there have been several studies which attempted to better characterize the active uptake process (Best and Fischer 1992). Typically, second- ary kills which resulted from consumption of con- taminated songbirds occurred at the time or soon after the time of insecticide application (often at seeding). Granular carbofuran was frequently im- plicated in this form of secondary kill. Investiga- tions have documented carbofuran incidents in more crops and exposure situations than any other product, which is perhaps a reflection of this in- secticide’s broad use as well as its high inherent toxicity. Several incidents were documented in corn (maize), grapes, winter wheat, cole crops and tree farms. Bald Eagles, hawks, Hen Harriers, ac- cipiters and owls have been poisoned (Table 4). Bucknell (1970, 1971) and Mills (1973) de- scribed extensive mortality of harriers in New Zea- land which died after pastures were treated with fensulfothion (5% granule) and parathion (10% granule). The granules were dyed green in an ef- fort to make them less conspicuous to birds, and the investigators saw very few granules in stomach contents suggesting that the harriers were poi- soned by scavenging birds (primarily magpies and gulls) which had themselves been poisoned by con- taminated grass grubs. Evidence that the granules had released most of their active ingredients when the kills occurred means that this route of expo- sure was like that seen following spray applications. Another frequent but less commonly recognized route of exposure to granular insecticides is passive uptake generally involving waterfowl species. Typ- ically, waterfowl are exposed to granular insecti- cides when they sift sediments and crop residues in puddles or waterlogged soils. Extensive kills of waterfowl have occurred in potato and root crops in British Columbia, Canada as well as in partially flooded corn, winter wheat and rice fields in the U.S. (Table 8). One interesting thing about these poisonings is that they occur at different times of the year, often several months postharvest. In Brit- ish Columbia, Canada, granular insecticides have had unexpected persistence (Wilson unpubl.). Sev- eral spring-applied products persisted in sufficient concentration to kill waterfowl and raptors second- arily throughout the following fall and winter. En- hanced persistence was attributed to soils of low pH, but the waterlogged nature of the soils may also have been a factor. Buck et al. (1986) followed Great Horned Owls {Bubo virginianus) using radiotelemetry in an Iowa farming area where granular formulations of the insecticides terbufos and chlorpyrifos were used and where small mammals were known to have been exposed and affected by the insecticides. They could not conclusively demonstrate exposure because the owls preferentially foraged in non- treated areas. Treated Seeds. Seed treatment is defined as the application of a pesticide to the seed prior to plant- ing. This can be a simple surface treatment or seeds can undergo a pelletization process where several combinations of pesticides, fertilizers or in- oculates can be applied in an inert waxy covering to the seed. Treated seeds represent another po- tential route through which high residues of insec- ticides can be transferred via ingestion of viscera from primarily kills. Historically, the use of OCs such as aldrin, heptachlor and mercurial com- pounds as seed treatments have been responsible for extensive secondary poisoning of raptors in North America and Europe. In North America, most seed is now treated with gamma HCH (lin- dane). In Europe, the trend has been to use OP and CB seed treatment chemicals, and we believe there will be a growing use of ChE inhibitors for this use in North America. Despite documentation of primary kills in the U.K. (e.g., geese from car- bophenothion and pigeons from fonofos and chlorfenvinphos [Greig-Smith 1987b]), there have been no reports of secondary poisoning in these incidents. Assimilated and Surface Residues from a Liquid Spray Application. In the case of highly-toxic insecticides, the chemical need not be present as concentrated granular material or seed treatment to secondarily affect raptors. There were documented instances with carbofuran, monocrotophos and parathion where residues were present in sufficiently high concentration in vertebrate prey following a spray application to cause secondary poisoning (Table 9). In registrant-sponsored field studies of carbof- uran in both corn (at 1. 1 kg a.i./ha) and alfalfa (at 0.55 kg a.i./ha), immobilized Hen Harriers were observed. One bird had been feeding on a rabbit (Mineau 1993). Similarly, several U.S. inci- dents were recorded in vineyards following the ap- plication of carbofuran to drip irrigation water when songbirds were attracted to the irrigation wa- ter for drinking and were then captured or scav- enged (Table 9) . Monocrotophos kills recorded in Israel (Mendelssohn and Paz 1977) were among the earliest kills of raptors ever recorded following 14 Mineau et al. VoL. 33, No. 1 Table 8. Documented cases of raptor poisoning from the approved (labeled) used of granular insecticides or seed treatment, in or on invertebrate or vertebrate prey. Granular Insecticide Crop Primary Kill Species Secondary Kill Species Refer- ences carbofuran corn (maize) songbirds, pigeons, rac- coon^, waterfowl, earthworms Bald Eagle American Kestrel Red-tailed Hawk Red-shouldered Hawk Hen Harrier Short-eared Owl Vulture sp. (S. Africa) 2, 3, 4, 5 rice waterfowl Red-tailed Hawk Northern Harrier 6 grapes songbirds Cooper’s Hawk Sharp-shinned Hawk American Kestrel Red-tailed Hawk Northern Harrier I*’ winter wheat fox^ Red-tailed Hawk Bald Eagle I’’ pine plantations small mammals Red-tailed Hawk Bald Eagle potatoes/root crops waterfowl Bald Eagle Red-tailed Hawk 7 cauliflower earthworms Little Owl 8 sugar beet earthworms Common Buzzard (Black and Red Kites also suspected) 9 fensulfothion pasture songbirds, small mam- mals (hedgehog), gulls, magpies Pacific Marsh-harrier 10, 11, 12 potatoes/root crops waterfowl Bald Eagle Red-tailed Hawk 7 parathion pasture magpies, gulls, song- birds, small mam- mals Pacific Marsh-harrier 12 phorate winter wheat waterfowl Bald Eagle Golden Eagle Northern Harrier Great Horned Owl Red-tailed Hawk l^ 13 potatoes/ root crops waterfowl Bald Eagle Red-tailed Hawk 14 terbufos potatoes/ root crops waterfowl Bald Eagle Red-tailed Hawk 15^> corn (maize) beetle larvae Swainson’s Hawk P fonofos potatoes/root crops waterfowl Bald Eagle Red-tailed Hawk 15 '^ disulfoton cotton unidentified insect pest Swainson’s Hawk 16 1 U.S. incident data. 2 Balcomb (1983). 3 Booth et al. (1983). 4 Stinson et al. (1994). 5 Ledger in Mineau (1993). 6 Littrell (1988). 7 Elliott et al. (1996). March 1999 Pesticide Poisoning of Raptors 15 Table 8. Continued. 8. Fletcher et al. (1989). 9. Dietrich et al. (1995). 10. Bucknell (1970). 11. Bucknell (1971). 12. Mills (1973). 13. C. Sowards and D. Fries, U.S, Fish and Wildlife Service, pers. comm. 14. Elliott etal. (1997). 15. Canada incident data. 16. Hamilton pers. comm. ® It is believed that the planters/seeders deposited granules on carcasses which were then scavenged. The mammals indicated as primary kills were probably not killed by the pesticide. The designation U.S. incident data or Canada incident data refers to cases tabulated in the current review but not yet published the use of ChE-inhibiting insecticides. Starting in 1975, farmers attempted to control voles in alfalfa fields with aerial applications of monocrotophos, often at rates higher than prescribed for insect control. Consequences for wildlife in general and raptors in particular were dramatic. Mass mortality of larks, thrushes, chaffinches, buntings and lap- wings were noted as were dead jungle cats and wild pigs. Following a 600 ha application in 1975-76, authorities recovered 219 individual raptors of 13 species dead or paralyzed including Greater Spot- ted {Aquila clanga) , Lesser Spotted {Aquila pomari- na) and Imperial Eagles, Long-legged {Buteo ruji- nus) and Common Buzzards, Black Kites, Western Marsh ( Circus aeruginosus) , Hen and Pallid ( C. ma- crourus) Harriers, Common Kestrel and Short- eared {Asia flammeus) , Long-eared {A. otus) and Barn Owls. It was estimated that the total kill was easily twice as high as the number of birds collect- ed (Mendelssohn and Paz 1977). The usual win- tering populations of birds were thought to be sup- plemented by migrants. The carnage continued in 1976-77 on a similar scale with White-tailed Eagle (Haliaeetus aUndlla), Merlin (Falco columbarius) , Eurasian Sparrowhawk and Eurasian Eagle Owl {Bubo bubo) added to the list. Spraying was reduced in the winters 1977-79 although a number of rap- tors were also found dead (Mendelssohn et al. 1979). This use of monocrotophos apparendy still occurs (Shlosberg pers. comm.). Monocrotophos when used at the lower rate of 0.5 kg a.i./ha against cutworm larvae in wheat caused the death of Short-eared Owls and a Northern Harrier, pre- sumably when they scavenged the multitude of songbirds also found dead or debilitated (Benson and Baker 1971). Of course, raptors manipulate their vertebrate prey extensively, whether in the process of killing. Table 9. Documented cases of secondary poisoning in raptors resulting from the approved (labeled) use of liquid insecticide sprays and consumption of vertebrate prey. Liquid Insecticide Crop Primary Kill Species Secondary Kill Species References carbofuran vineyard songbirds, small mammals Red-tailed Hawk Sharp-shinned Hawk U.S. incident data corn ? Northern Harrier FMC 1989 in Mineau (1993) alfalfa songbirds, rabbit Northern Harrier White-tailed Kite U.S. incident data FMC 1989 in Mineau (1993) parathion pasture lapwings and others Red kites Smit et al. (1986) Over (1989) wetlands Quelea many species — see section 2.2.4 see text monocrotophos wheat songbirds, pheasant, small mammals Northern Harrier Short-eared Owl Benson and Baker (1971) fenthion wetlands Quelea many species — see section 2.2.4 see text 16 Mineau et al. VoL. 33, No. 1 plucking or eviscerating. The primary vertebrate kills, especially small birds and mammals, can carry an appreciable load of residues on their fur or feathers from being in contact with an aerosol or entering a freshly-sprayed field. It is difficult to conclude whether secondary poisoning is a result of consuming viscera or surface residues or both. Avicides. Some bird control programs use ChE inhibitors and it is not surprising that raptors at- tracted to the easy source of food are killed. In North America, the main use of ChE inhibitors for bird control has been the Rid-a-Bird® perch. It consists of a hollow mesh perch with a wick soaked in a solution of 11% fenthion. Pest birds are ex- posed through their feet and undersides when they land on a perch. The perches are labeled for the control of European Starlings, House Sparrows and pigeons in North America. Hunt et al. (1991, 1992) experimentally demonstrated the risk of sec- ondary poisoning from the use of fenthion in Rid- a-Bird® perches. A single contaminated sparrow proved lethal to 9 of 10 kestrels. Furthermore, they also demonstrated that exposed sparrows were more than 16 times more likely to be captured by American Kestrels than their unexposed flock- mates. At least 21 cases of fenthion poisoning involving Rid-a-Bird® perches were reported from 1984—94 (Table 10). In a third of the cases, the use of the perches was not positively established or was still under investigation. Cases continued to be report- ed in 1995 and 1996. A 1986 Illinois incident involving trained and fe- ral Red-tailed Hawks (Wenneborg 1986) resulted in symptoms that began six hours after consump- tion of a single starling and continuing for at least 24 hr despite repeated treatments with atropine sulfate and protopam chloride. Only when birds regurgitated pellets did recovery begin. Another incident involved a falconry-trained Cooper’s Hawk (Accipiter cooperii, Keltsch-Richter 1989). La- combe et al. (1994) reported that perches were suspected in Merlin kills in western Canada, but evidence was not available. Fenthion has also been one of the main avicides used in the control of Red-billed Quelea {Quelea quelea) in several African countries (Keith and Bruggers 1998). Typically, quelea roosts are sprayed by aircraft at sundown but ground appli- cations to crops, roosts and water holes are also made (Thomsett 1987) . Thomsett reported that 41 dead or dying raptors were found shortly after a 1984 control program in Kenya. They included Cape {Bubo capensis) and Verreaux’s {B. lacteus) Ea- gle Owls, Secretary Bird {Sagittarius serpentarius) , Gabar Goshawk {Micronisus gabar), Augur {Buteo augur) and Lizard {Kaupifalco monogrammicus) Buz- zards, Tawny Eagle {Aquila rapax) and Black-shoul- dered {Elanus caeruleus) and Swallow-tailed Kites {Elanoides forficatus) . Quelea were observed dying up to nine days post-spray, carrying the impact far- ther afield. According to Bruggers et al. (1989), Thomsett’s unpublished field report extends this period to 19 days. The raptors died either from capturing dead or debilitated quelea and, in some cases, were exposed directly. Surveys conducted be- fore and after the spray indicate that the usually plentiful raptor community had been almost com- pletely eradicated. As a result of these reports, a study was initiated in Kenya in 1985 (Bruggers et al. 1989). Two col- onies of quelea (50 ha in total) were treated with fenthion under rigorously controlled conditions. Results were similar and, although some quelea died by the morning following spray, some died up to seven days post-spray. Affected quelea were found over 35 km^ surrounding one of the colo- nies. Twenty-three raptors of six species including Tawny and Bateleur ( Terathopius ecaudatus) Eagles, Gabar and Pale-chanting {Melierax canorus) Gos- hawks, Pygmy Falcons {Polihierax semitorquatus) and Pearl-spotted Owlets {Glaucidium perlatum) were captured before the spray and fitted with radio- transmitters. Post-spray, an instrumented Pearl- spotted Owlet and Tawny Eagle were found mori- bund and sacrificed. A sick Pygmy Falcon was also collected. A second Tawny Eagle was found debil- itated but was not collected. Based on ChE data, at least 16 of the 23 raptors were exposed. In all, 17 species other than quelea were found dying after spraying and this, despite overnight scavenging rates as high as 90% at one site. Residues on quelea were found to be sufficiently high to kill most rap- tor species. Following applications to two small wet- lands (5 ha and 0.5 ha) in Kenya in 1988, Keith et al. (1994) reported 84 birds of 20 species dead or debilitated. However, the impact on raptors was not evaluated because few were seen in the vicinity. Callahan and Ferreira (1989) reported finding six dead or incapacitated Common Buzzards following treatment of a 20 ha quelea colony in South Africa, but this did not represent an exhaustive survey. Fenthion is not the only OP insecticide to be used for quelea control. Thiollay (1975), reporting March 1999 Pesticide Poisoning of Raptors 17 on the use of ethyl parathion in Mali, counted 400 dead Black Kites following treatment of a single 8- ha quelea colony. Both European (M. m. migrans) and African {M. m. parasitus) subspecies were killed. He also made reference to a large number of other diurnal and nocturnal raptors associated with quelea colonies and estimated that between 92-100% of nontarget species (whether or not they were quelea predators or scavengers) were killed by the treatments compared to 38% of young and 2% of adult queleas. In South Africa, spraying of quelea colonies prior to 1986 was primarily with ethyl parathion (Tarboton 1987). One monitored spray yielded 16 Tawny and Steppe (Aquila nipalen- sis) Eagles as well as 46 Black Kites. A Wahlberg’s Eagle {Aquila wahlbergi) was also reported by Tar- boton (1987) as being poisoned in a separate spray Topical Treatment of Livestock and ‘Medicated’ Livestock Feed. One of the earliest documented incidents of secondary poisoning by a ChE inhib- itor proved to be also one of the most intriguing. It concerned the use of the OP famphur poured on the back of livestock to control warble fly larval parasites (grubs) systemically. According to Henny et al. (1985), ranchers had begun reporting kills of magpies associated with the use of famphur as early as 1973, shortly after its introduction to the U.S. market. The first formal account of famphur poisoning documented mortality of Black-billed Magpies {Pica pica) , European Robins {Erithacus ru- becula) and Dunnock {Prunella modularis) in Great Britain (Felton et al. 1981). It was noteworthy that similar problems with fenthion used for warble fly treatment were reported the very same year in Canada (Hanson and Howell 1981). Henny et al. (1985, 1987) and Franson et al. (1985) described secondary poisoning of raptors associated with pri- mary kills of Black-billed Magpies and European Starlings. Henny et al. (1985, 1987) found that magpies were poisoned when they ingested hair from topically-treated cattle. Red-tailed Hawks scav- enging the magpies died from secondary poison- ing and a case of tertiary poisoning of a Great- Horned Owl scavenging one of the dead hawks was even documented. Despite the detailed investigative work of Henny and colleagues, the incident record for famphur remains complex and confusing. Not all incidents involved magpies. Several cases of secondary poi- soning appeared to have originated from black- birds or starlings that had fed on treated grain. Application of pesticides to grain is a common tac- tic for those intent on abusing pesticides to control pest birds, and famphur has been used for this pur- pose around farm fields (White et al. 1989). In many cases, however, pesticide abuse was techni- cally inseparable from normal labeled use of the product because the OP can legally be delivered to cattle through their feed although this is appar- ently not the favored technique. Table 11 repre- sents an attempt to categorize U.S. famphur inci- dents on the basis of investigation reports and necropsy information largely on content of the bird’s crop. One consequence of this complexity in the incident record was that relatively few inci- dents could be categorized as clear abuse cases or clear labeled-use cases. Also, in early years, incident investigators did not know that famphur could per- sist in the hair of treated cattle for >100 d. There- fore, eagles that died weeks or months after cattle were treated were automatically assumed to be abuse cases. In Britain, the use of famphur as a topical insecticide was linked to the death of mag- pies on several occasions (Felton et al. 1981, Fletcher et al. 1990) and there was a probable case of raptor secondary poisoning on record. Two Common Buzzards were found with residues of famphur in one incident in 1993. Small birds were found in their gizzards (Fletcher et al. 1994). Fewer cases were recorded with the use of fen- thion used as a ‘pour on,’ but this may simply have reflected the extent of use. Henny et al. (1987) described a number of Bald Eagles killed by fen- thion obtained from having scavenged small pigs from a farm where sows were treated. It was not clear how the fenthion had been transferred from sow to piglets although abuse was not indicated. In the U.K., fenthion was approved for the control of warble fly larvae in cattle, but this approval was withdrawn in 1994. Between 1985-94, 26 cases of fenthion poisoning were reported in Britain. Be- cause some baits were found in some of the inci- dents and most of the incidents occurred in areas of largely sheep rather than cattle farming, all cases were ascribed to abuse. In at least two cases, lamb flesh was confirmed in the ingesta. Fenthion never was registered to treat lambs and it was sus- pected that lamb carcasses were treated with fen- thion to kill corvids. It was noteworthy that one of the two documented fenthion cases in Canada was the result of an attempt to control ectoparasites in lambs. Although categorized as a case of abuse (Ta- ble 4), there was no willful attempt to poison rap- 18 Mineau et al. VoL. 33, No. 1 Table 10. U.S. kills caused or strongly suspected of being caused by use of the Rid-a-Bird® perch with fenthion (1984—95). Sources; unpublished U.S. reports compiled for this review as well as Wenneborg (1986), Keltsch-Richter (1989), Franson et al. (1996) and Long (pers. comm.). Year State Species Affected (Number Found) Pest Species or Other Primary Kills Site Notes 1986 IL Great Horned Owl (4) Red-tailed Hawk* (1) Starlings, Grackles, House Sparrows Generating sta- tion According to unconfirmed reports, at least 21 hawks and owls died in this incident. 1987 IL Sharp-shinned Hawk (1) Red-tailed Hawk (10) Rough Legged Buzzard (10) Great Horned Owl (1) Barred Owl (1) Starlings (primarily) Oil refinery 1988 lA Eastern Screech Owl (1) House Sparrows NR Owl was said to have land- ed on the perch. 1988 IL Snowy Owl (1) Cooper’s Hawk (1) Starlings Oil refinery These occurred at the same site but represent different attempts to control pest birds. 1988 IL Barred Owl (1) American Kestrel (1) Screech Owl (1) Starlings Oil refinery 1989 WA Short-eared Owl (1) Starlings, Rock Doves Industrial site 1989 OH Barred Owl (1) Barn swallows NR 1989 IL Cooper’s Hawk* (1) Starling NR Use of perches not estab- lished or under investi- gation. 1992 VA Peregrine Falcon (1) Rock Doves Air Force Base 1992 OH Peregrine Falcon (1) Rock Doves City Use of perches not estab- lished or under investi- gation. 1992 MO Red-tailed Hawk* (1) Rock Doves Open land near airport Use of perches not estab- lished or under investi- gation. 1992 IL Cooper’s Hawk (3) Hawks spp. (3) Owl spp. (6) NR Oil refinery Another report of 2 Red- tailed hawks may be re- lated to this kill. 1993 MO Peregrine Falcon (1) Unidentified bird City Use of perches not estab- lished or under investi- gation. 1993 MO Great Horned Owl Mourning Doves, Rock Doves Correctional facility Use of perches not estab- lished or under investi- gation. 1994 MO American Kestrel (1) NR Bird near air- port hangar Use of perches not estab- lished or under investi- gation. 1994 MN Peregrine Falcon (1) Rock Doves Residential driveway Use of perches not estab- lished or under investi- gation. 1994 OK Red-tailed Hawk (6) Barred Owl (1) Starlings, American Robins Feedlot 1994 KS Red-tailed Hawk (5) Screech Owl (1) NR NR March 1999 Pesticide Poisoning of Raptors 19 Table 10. Continued. Year State Species Affected (Number Found) Pest Species or Other Primary Kills Site Notes 1994 MN Peregrine Falcon (1) NR City 1994 MN Peregrine Falcon (1) NR City Found 16 km away from previous bird. May rep- resent a single applica- tion site although perch- es used in several locations. * Falconry bird. tors and the user was not prosecuted (Bowes et al. 1992). McKenzie et al. (1996) diagnosed cases of poisoning of several scavenging species (although no raptors) in 1993-94 in Australia. Although fen- thion was registered as a pour-on treatment for cat- tle, they were unable to trace the source of the chemical or to determine whether the cases might have resulted from malicious poisoning. In 1992, one case involving a Red Kite and an unspecified use of diazinon was recorded in the U.K. where diazinon was approved as a sheep dip. Given the propensity of the kites to feed on lamb carcasses, this seemed a likely route of exposure although this could not be confirmed. Also in 1992, a dead nestling Red Kite was found to have been exposed to propetamphos, another sheep dip approved for use in Britain (Fletcher et al. 1994). Because of the low residue level (0.05 mg/kg), the bird was not thought to have been willfully poisoned. Finally, a Red Kite was found poisoned by phosmet (Fletcher et al. 1991). This insecticide is approved for warble fly treatment in a variety of livestock; however, residue levels of 8300 mg/kg suggested deliberate poisoning rather than the birds having fed on the carcasses of treat- ed livestock. Dermal Exposure in Treated Areas. The poten- tial for direct dermal exposure of raptors to pesti- cides is the same as for any other group of birds entering treated areas. Although relatively few data are available to assess the relative contribution of dermal exposure in most pesticide use situations, the dermal route is clearly important or even dom- inant in some cases (Mineau et al. 1990, Driver et al. 1991, Henderson et al. 1994, Shlosberg et al. 1994). There is one notable U.S. use pattern where dermal exposure clearly dominates, that being the exposure of raptors to insecticides applied in dor- mant oils to almond and stone fruit orchards in California. Many incidents and kills of Red-tailed hawks are known to have occurred in orchards. Hooper et al. (1989) live-trapped 12 Red-tailed Hawks in 1986 and 1987 and found 67% showing ChE inhibition. Following on this work. Fry et al. Table 11. Summary of U.S. famphur incidents (1985-94) broken down by apparent crop content at necropsy. Nature of Ingesta Abuse Labeled Use Circumstances Unknown Totals grain and bird remains 5 — 4 9 magpie remains^ — 2 — 2 hair and bovine tissue 1 4 12 17 small mammal — — 1 1 bird remains — — 8 8 mixed bird and mammal remains — — 3 3 fish remains 1 — — 1 unspecified crop contents 1 — 9 10 Totals 8 6 37 51 ® Bird remains were only infrequently identified to species. 20 Mineau et al. VoL. 33, No. 1 (1998) used radio telemetry and pesticide-use data correlated with foot-wash residues and plasma ChE to assess the relative contributions of a number of different OP pesticides to the ‘effective’ exposure in Red-tailed and Red-shouldered Hawks using the orchards. Of the pesticides studied (ethyl parathi- on, diazinon, methidathion and chlorpyrifos) , parathion contributed the most to the measured level of inhibition in the birds. Parathion use in dormant-oil sprays was canceled in December 1991. In more recent years (1993-94), a number of incidents have been associated with exposure of birds to the other three OP insecticides (Hosea pers. comm.). Most of the birds did not appear to die from toxicosis. For most, trauma such as elec- trocution, entanglement or impact was diagnosed as the proximate cause of death. Based on de- pressed ChE levels as well as pesticide residues ex- tracted from feathers or foot washes, pesticides were frequently ascribed a contributory role only. Nevertheless, we included some of these incidents. A good analogy from a human perspective would be traffic accidents and impaired driving: the exact circumstances surrounding accidents are varied, yet the root cause is impairment. Continuing the analogy, the situation is made more complex by the fact that motor vehicle accidents occur even without alcohol. The role that ingesting contami- nated prey may play in some of these incidents has not been assessed. Although foot and feather wash- es are routinely analyzed, crop contents are not. Risk Factors Contributing to Raptor Poisoning We have discussed several risk factors in the con- text of exposure routes. Some of the more signifi- cant factors that result in raptor poisonings are in- sectivory and vermivory, opportunistic taking of debilitated prey, scavenging (especially if the gas- trointestinal tracts are consumed), presence in ag- ricultural areas, perceived status as pest species and flocking or other gregarious behavior at some part of the life cycle (e.g., a geographically-restricted breeding, migration or wintering area) . There are other risk factors of overarching im- portance, namely the toxicity of ChE inhibitors and the relative sensitivity of raptors to OP and CB pesticides. Toxicity to Birds of In-use Pesticides. Poisoning incidents occur frequently because many ChE-in- hibiting pesticides are acutely toxic to birds. Also, the importance of cholinergic systems is such that, even if exposure does not cause immediate death. many sublethal manifestations of exposure to ChE inhibitors can lead to reduced survival in exposed individuals (Grue et al. 1991). Based on their re- view of poisoning cases, Grue et al. (1983) con- cluded that a large proportion of incidents can be explained by toxicity and extent of use. Inherent in their conclusion is that exposure is inevitable, or at least difficult to limit in many cases. In light of this, we compared the use of ChE-inhibiting pes- ticides in the U.S. with that in the U.K since there appears to be a dramatic difference in the relative proportion of labeled-use cases to the total number of cases in these two jurisdictions (Table 12). Un- fortunately, a similar comparison could not be made with Canada because there were no compre- hensive statistics on pesticide use. We assumed that the 1994 pesticide data were representative of the 1985-95 period summarized. It should be noted that pesticides not currendy used on crops such as famphur and fenthion were excluded. We found that the use of ChE inhibitors (expressed as tons of a.i./ha of cropland) was al- most three times higher in the U.S. than in the U.K. For the U.K., six compounds accounted for >85% of the total tonnage of ChE inhibitors used (Garthwaite et al. 1994). Of these, only aldicarb (8.2% of ChE-inhibiting tonnage) has an HDg (Hazardous Doses) value (the avian LD 50 value cal- culated to be at the 5% lower tail of the distribu- tion of all avian LD 5 Q values with a 50% probability for that compound) <1 mg/kg (Table 13). By comparison, in the U.S., we included 16 pesticides in order to account for a similar proportion of the total tonnage of ChE-inhibitors (Gianessi 1995). Six of the 16 (or 32% of the total tonnage) were pesticides with an HD 5 <1 mg/kg. It was notewor- thy that labeled use incidents in the U.K. (Table 3) were all associated with pesticides considered minor in that country but which are all major use products in the U.S. (carbofuran, phorate, fam- phur). We concluded that the proportionate dif- ference in labeled vs. abuse cases in the two coun- tries was a direct result of the products in use. There was a higher reliance in the U.S. on ChE- inhibiting insecticides having an extreme toxicity to birds. A comparison of the absolute number of cases in the two countries was more difficult because re- porting rates are known to differ. Given that ‘un- known’ cases in Tables 2 and 3 followed a similar labeled use to abuse proportion noted for cases where circumstances are known, national author!- March 1999 Pesticide Poisoning of Raptors 21 Table 12. Reported sales and intensity of use of organophosphate and CB pesticides for the U.S. and U.K. in 1994, top selling products and their toxicity to birds. Country Arable Land (Million ha)^ Tonnes ChE Inhibitors USED^ Intensity OF ChE Inhib. Use Per ha Top ChE-Inhibiting Insecticides in Crops Making Up >85% of THE Total Tonnage Tonnes Avian HD 5 for 20 g Bird^ (mg/kg) U.S. 165 37,413 0.23 kg chloropyrifos 6697 3.8 a.i./ha terbufos 3492 0.35 methyl parathion 2704 2.5 carbofuran 2314 0.055 carbaryl 2073 49.0 phorate 2020 0.21 aldicarb 1825 0.46 acephate 1538 23.0 malathion 1532 152.0 demethoate 1188 5.9 azinphos methyl 1097 2.5 fonofos 1076 4.1 parathion 1051 0.42 profenofos 936 N/A disulfoton 819 0.56 U.K. 6.99 571 0.082 kg dimethoate 213 5.9 a.i./ha chlorpyrifos 133 3.8 pirimicarb 50.6 7.2 aldicarb 46.9 0.46 triazophos 37.4 2.9 demeton-S-methyl 11.7 8.3 ^ After Cobham and Rowe (1986). 2 U.S. data from Gianessi (1995); U.K. data from Garthwaite et al. (1994). Updated from Baril et al. (1994), Mineau et al. (1996). ties have documented, on average, about 12 la- beled-use cases per year and 0.5 labeled-use cases per year in the U.S. and U.K., respectively. How- ever, when expressed as cases/ ton of OP or CB in use (Table 12), the number of reported labeled- use incidents was 2.8 times higher in the U.K. than in the U.S. which is counter to the trend expected. If we accept the relationship between the toxicity of in-use pesticides and the likelihood of labeled- use incidents, we need another reason to explain the difference. The most likely hypothesis is that U.S. incidents are under-reported by at least 2.8 times relative to Britain. A higher reporting rate in Britain could easily be explained by a combination of smaller field sizes, a higher human population density, a high level of interest in avian welfare and a long-standing incident investigation system. In fact, the difference in reporting rates is likely to be higher because we suspect a far higher number of labeled-use cases in the U.S. for every ton of ChE inhibitor used. However, it is also possible that the more intensive use of cropland by raptors in Brit- ain increased the probability of exposure to even minor-use products. The limitations of this analysis are readily appar- ent. Most important, we had no knowledge of the actual incident rate and could only compare the two countries in relative terms. Also, the compari- son did not take into account the specific use pat- terns of the various products. Even low-use prod- ucts such as fenthion used in Rid-a-Bird® perches can have a measurable impact on the incident re- cord. Finally, the analysis ignores differing biases in the two countries with respect to the reporting of raptor incidents. Relative Sensitivity of Raptors to ChE Inhibitors. There was only very limited information on the senstitivity of raptors to ChE inhibitors relative to other birds. We (Mineau et al. 1996) showed that a significant degree of variance in interspecies sen- 22 Mineau et al. VoL. 33, No. 1 Table 13. Acute toxicity data available for raptors compared to predicted (best fit) avian toxicity data for an average bird of the same size. Pestictde No. Avail- able LD 50 S Regres- sion R Square^ Intercept (a) Slope (b) Species Measured LD 50 Calcu- lated (Best Fit) LD5„» monocrotophos 24 0.77 -2.5603 0.9695 Golden Eagle 0.1881 2.1 Screech Owl 1.52 2.4 American Kestrel 1.52 2.4 fenthion 25 0.82 -2.8346 1.2802 Screech Owl 3.92 6.1 American Kestrel 1.42 5.6 EPN 14 0.56 -2.8788 1.4327 Screech Owl 2742 12.0 American Kestrel 42 10.6 carbofuran 18 0.65 -2.9455 1.0787 American Kestrel 0.62 1.7 Screech Owl 1.92 1.7 methyl parathion 10 0.86 -2.3540 1.1646 American Kestrel 3.13 9.8 ® Mineau et al. (1996). Proportion of variance explained by linear regression of the form: Log(LD 5 o) = a + b (log weight in grams) . ’’ Assuming mean (mixed sex) weight of 123 g for American Kestrel, 164 g for Screech Owl after Wiemeyer and Sparling (1991), and 4300 g for Golden Eagle after Dunning 1984. 1 Hudson et al. (1984). 2 Wiemeyer and Sparling (1991). 3 Rattner and Franson (1984). sitivity to pesticides (based on a sample heavily weighed to ChE inhibitors) could be explained by allometric scaling and that, in general, large-bod- ied birds were less sensitive than small-bodied birds. This suggested that, when estimating the av- erage sensitivity of birds to any given pesticide, their weights should be taken into account. Table 9 reviews measured acute toxicity data endpoints in raptors with projected values calculated from a ‘best-fit’ of all available avian data and the weight of the species. Although it is difficult to generalize from so few data points (only three raptor species, 10 species-chemical combinations), raptors appear to be more sensitive than birds of similar size in eight of 10 comparisons. One exception was the apparent insensitivity of Eastern Screech Owls to EPN. Our tentative finding is that raptors may in- deed have an inherent sensitivity to ChE inhibitors, thereby justifying the use of the 95% protection level (the use of a calculated HD 5 ) when assessing the risk of ChE-inhibitors to raptors. The Conservation Aspects of Raptor Poisoning Incidents It is generally recognized that bioaccumulation of OC pesticides has had a devastating effect on raptor populations, especially in the 1950s and 1960s at the height of their use (Newton 1979). It is important to recognize that the effect of these pesticides was two-fold, causing eggshell- thinning effects from DDE as well as direct poi- soning from accumulated cyclodiene residues, principally aldrin and dieldrin used as seed treat- ments. The mortality of birds of breeding age from cyclodiene seed treatments had the most profound influence on the population dynamics of the Eurasian Sparrowhawk in Britain (Newton and Wyllie 1992). Adult mortality, especially in the spring, was probably additive because known density-dependent sources of natural mortality operated over the winter months. Similarly, the use of dieldrin for grasshopper spraying was the most important factor associated with declines of Merlins from Saskatchewan, Canada (Houston and Hodson 1997). Noer and Secher (1990) showed that a ban on hunting in Denmark rather than the coincidental decline in the use of OC insecticides was responsible for the 1970s increas- es in populations of Common Buzzards, Eurasian Sparrowhawks and Goshawks. Similarly, increases in mortality rates and not a decrease in reproduc- tive success were thought to be responsible for the more recent declines in these species (Noer and March 1999 Pesticide Poisoning of Raptors 23 Secher 1990). It stands to reason that we should consider the potential of current pesticides to in- crease mortality rates in raptors, especially that of breeding adults. In Britain, raptors have been poisoned with ChE- inhibiting pesticides and other chemicals (e.g., al- phachloralose, strychnine) and they have been persecuted through nonchemical means. This per- secution has played, and in some cases, continues to play, an important role in the population dy- namics of several species. Historically, persecution led to the extirpations of the Goshawk, Marsh Har- rier, Osprey {Pandion haliaetus) and White-tailed Eagle from the British Isles (British Trust for Or- nithology et al. 1997). Currently, it is estimated that half of all Welsh Red Kites die prematurely from poison baits (Davis 1993). Between 1971-93, 44 Red Kites were confirmed to be illegally poi- soned in the British Isles (Evans et al. 1997). The total breeding population in 1996 was estimated at 182 and, recently, birds have been introduced from Spanish stock. Persecution has also had a measur- able effect on Golden Eagles and Hen Harriers in Scotland as well as Common Buzzards in western Britain (British Trust for Ornithology et al. 1997). In some cases, persecution may be preventing some species from regaining part of their former range (e.g., Common Buzzard, Elliott and Avery 1991) . Although the availability of highly toxic pes- ticides undoubtedly exacerbates the persecution problem, abuse cases per se do not offer a very strong argument for regulatory changes in pesti- cide approvals or labeling. Given the small number of labeled-use incidents documented yearly in Britain, there is general agreement that current labeled pesticide use does not present a problem for raptors. However, it is recognized that efforts to document causes of mor- tality in raptors are heavily biased toward those forms of mortality most readily detected by people (Newton et al. 1992) . For British Eurasian Sparrow- hawks in the 1980s and 1990s, the leading cause of mortality appeared to be collision with windows. For Common Kestrels, it was collisions with cars. Nevertheless, in the period from 1963-75, follow- ing many years of heavy use of aldrin/dieldrin seed dressings, at least 50% of Eurasian Sparrowhawk mortality and 39% of Common Kestrel mortality in southern Britain was attributable to aldrin or diel- drin intoxication (Newton et al. 1992). Although they did not analyze for intoxication by OPs and CBs in the post-OC period, they concluded that the influence of these chemicals was negligible based on the fact that the proportion of nontrauma and nonstarvation deaths declined to almost nil follow- ing the removal of OCs. This conclusion failed to consider any potential association between intoxi- cation and trauma documented on numerous oc- casions in the U.S. The magnitude and relative importance of rap- tor mortality from ChE-inhibiting pesticides in North America and elsewhere is more difficult to estimate. Several declining raptor populations oc- cur on the prairies of Canada, notably Burrowing Owl, Swainson’s Hawk, Northern Harrier, and Short-eared Owl (Kirk and Hyslop 1998). The as- sociation between the disappearance and repro- ductive failure of Burrowing Owls and the use of the insecticide carbofuran used for grasshopper control was well-documented (Fox et al. 1989). Similarly, large kills of Swainson’s Hawks have been reported from the use of monocrotophos in Ar- gentina (Woodbridge et al. 1995, Goldstein et al. 1996, Goldstein 1997, Canavelli and Zacagnini 1996). It is fortunate that the hawks are well-mixed on their wintering grounds or the impacts on some regional subpopulation (s) could have been greater (Henny et al. in press). Other factors can also ex- plain the decline of prairie species. Burrowing Owl populations continued to decline even in years of reduced insecticide use and Swainson’s Hawk breeding success is thought to have been reduced by habitat loss and food availability. The impor- tance of OP and CB intoxication relative to other diagnosed sources of mortality was highly variable (Table 10). Very few birds were ever checked for GhE depression when an obvious cause of mortal- ity (e.g., electrocution, trauma) was diagnosed. Routine screening of ChE levels in all raptors brought to one Virginia rehabilitation center (Por- ter 1993) indicated that traumatic injuries fre- quently accompanied exposure to a ChE-inhibiting chemical. On a global scale, several authors who have re- viewed the status of tropical raptor populations have mentioned agricultural intensification and the increased used of pesticides in intensive monocultures, such as soybean, sugarcane and rice, as potential or suspected threats (Bierre- gaard 1998, Virani and Watson 1998, Thiollay 1998, Mooney 1998). On a regional level, in- creased bird mortality resulting from exposure to ChE-inhibiting pesticides can be significant, es- pecially in the case of rare species. Attempts to 24 Mineau et al. VoL. 33, No. 1 kill foxes with carbofuran-laced baits caused the loss of at least seven Eurasian Black Vultures as well as a Golden Eagle in Northern Greece (An- toniou et al. 1996). It was estimated that only 16 pairs of Eurasian Black Vultures remained in Greece (del Hoyo et al. 1994). Thomsett (1987), based on his observation of quelea control oper- ations, believed that the use of fenthion was large- ly responsible for a regional decline in raptor populations in Kenya. Van Jaarsveld (1987) de- scribed the willful poisoning of at least 292 vul- tures over a 19-mo period in Kruger National Park, South Africa. This was of obvious concern because many species are concentrated in such protected areas. Pesticide poisoning resulting from apparently normal use of soil insecticides is a primary cause of death among Bald Eagles win- tering in the Fraser River Delta of British Colum- bia, Canada (Table 14), In that area, the winter- ing Bald Eagle population increased dramatically beginning around 1978 which coincided with the first reports of pesticide poisonings (Elliott et al. 1997). The population increase was thought to re- flect the continent-wide species recovery in the post-OC era (Kirk and Hyslop 1998). More win- tering eagles increased the scavenging pressure and the chances that pesticide-poisoned ducks were found and consumed by eagles. Although poisoning of some local breeding birds was doc- umented (Elliott et al. 1997), the local breeding population appeared to be stable or even increas- ing (Elliott et al. 1998). Whether or not an increase in mortality result- ing from pesticide use is sufficient to affect popu- lation structure or reproductive potential of affect- ed populations, two points remain. This mortality is preventable at litfle or no cost to the farmer or society at large. A comparison between the U.S. and the U.K. situations indicates that a more ju- dicious use of insecticides may greatly reduce the number of labeled-use cases, that a few products and/or formulations are responsible for most of the problems and the continuing problem with currently-registered pesticides is completely at odds with the effort and expense that groups and individuals in our society are willing to expend in order to rescue and rehabilitate individuals of those species. Regulatory Outlook for Pesticides Most Frequently Involved in Raptor Kills Only a few products and/or formulations are re- sponsible for most pesticide problems. Carbofuran. Carbofuran is the insecticide most frequently associated with labeled-use raptor mor- tality in North America as well as in the U.K, It was also implicated in the mortality of Bald Eagles in British Columbia, Canada before it was with- drawn from use (Mineau 1993, Elliott et al. 1996) . The existing evidence points to a widespread mor- tality from both granular and liquid formulations in several crops (Tables 8 and 9). In the U.S. and Canada alone, kills from granular carbofuran have been documented in at least 89 species from 24 different families of birds, reflecting the scale and the breadth of the impact from this pesticide and the resulting high risk to scavenging species (Table 15). The sand-core formulation of carbo- furan has now been severely restricted in the U.S. but continues to be used in rice and in a few mi- nor crops despite a resolution of the American Ornithologists’ Union asking the American gov- ernment for a total ban (American Ornitholo- gists’ Union 1990) and despite similar requests from the USFWS. This formulation was canceled in Canada (Pest Management Regulatory Agency 1995) although the fate of another granular for- mulation, this time on a corncob base, is still hotly debated. The corncob granules, being somewhat larger than the sand core granules, contain ap- proximately three times as much active ingredient as other granular bases of equivalent concentra- tion. Several kills of songbirds have been report- ed, proving that this granule base is also attractive to birds (Mineau 1993, unpubl. data). Therefore, the risk of secondary poisoning is also present with this formulation although no cases have been reported to date. The corncob-based for- mulation was also available in the U.S. through local ‘special-need’ registrations but these may be revoked because of increasing concerns over cu- mulative exposure of the human population to ChE-inhibiting pesticides (the new U.S. Food Quality Protection Act) . From a North American perspective, there is a continuing concern for mi- gratory bird species from sand-core formulations of carbofuran that are widely registered in Mexi- co, Central and South America. They continue to be used on a very wide array of crops including rice, cotton, hemp, tobacco, peanuts, maize, cof- fee, bananas, oil palm, sugarcane, sorghum, cit- rus, potatoes, tomatoes and peppers. The registration of the liquid formulation of car- bofuran for grasshopper control and any use of the product in alfalfa were canceled in Canada (Pest March 1999 Pesticide Poisoning oe Raptors 25 Management Regulatory Agency 1995). Unfortu- nately, the product continues to be used in corn and other crops despite evidence that primary kills of songbirds occur. The liquid formulation in- creased in popularity in the U.S. following the par- tial removal of the sand-core granular formulation. One of the principal uses of carbofuran in the U.S. (for control of rootworm in corn) is often unnec- essary where crop rotation is practiced. Unfortu- nately, even growers that practice crop rotation continue to use the product prophylactically in the mistaken belief that it will increase yields (V. So- renson pers. comm.). Monocrotophos. This insecticide is the second most used OP in the world with the bulk of its market in the developing world (Voss and Schatzle 1994) . The Swainson’s Hawk incident in Argentina revived concerns over this product and raptor pop- ulations, concerns that were first expressed in Is- rael in the context of large-scale mortality of mi- grating raptors (Shlosberg 1976, Mendelssohn and Paz 1977, Mendelssohn et al. 1979). The use of monocrotophos to control voles (an abuse of the label) apparently continues in Israel (Shlosberg pers. comm.). Mass mortality of other species had also been recorded when the product was in use in the U.S. (e.g., 10000 American Robins [Turdus migratorius] in Florida potato fields; Lee 1972, Ste- venson 1972). The Swainson’s Hawk situation has now improved through label changes and a vol- untary withdrawal of the product from some agri- cultural areas. However, current problems with this product are not limited to grasshopper control, or to Swainson’s Hawks or to abuse cases in Israel, South Africa, Argentina and elsewhere. With the assistance of two of the transnational manufactur- ers of monocrotophos (Novartis and American Cy- anamid) a review of the worldwide database on this product is underway (Mineau et al. unpubl. data) . In February 1998, Novartis Corporation an- nounced that it was phasing out its production of monocrotophos worldwide. There are no indica- tions that other manufacturers will follow suit. There are about 30 manufacturers of this pesticide worldwide. Together, they produce about 30 000 tons of monocrotophos annually, or enough to treat an estimated 60—120 million ha at the com- monly used application rates (Novartis Corpora- tion pers. comm.). Fenthion Used as an Avicide. Extensive bird mortality associated with the use of fenthion for mosquito control was documented as early as the 1960s (Beard 1969 in DeWeese et al, 1983, Keith and Mulla 1966) and continued to be documented through the 1970s (Seabloom et al. 1973) and 1980s (Zinkl et al. 1981, DeWeese et al. 1983) al- though raptors were not reported killed in those studies. Despite documentation of nontarget bird kills from fenthion used for quelea control in 1984 (Thomsett 1987) and the Food and Agriculture Organization’s (FAO) own sponsored studies in 1985 (Bruggers et al. 1989) and 1988 (Keith et al. 1994), it continues to be the principal control agent for quelea. Fenthion replaced parathion which was considered too toxic for the applicators and bystanders (Meinzingen et al. 1989). The lim- ited market for a more selective avicide as well as the higher cost of alternatives mean that the use of fenthion is likely to continue. Fenthion contin- ues to be registered in the U.S. for mosquito con- trol despite the evidence of bird kills and the avail- ability of alternatives. Until March 1998, Rid-a-Bird® perches contin- ued to be used in the U.S. despite ample docu- mentation of frequent kills of protected and en- dangered raptor species such as Peregrine Falcons {Falco peregrinus). The USFWS won several court cases and out-of-court settiements against users. In March of 1998, the manufacturer applied for a vol- untary cancellation in the U.S. with a one-yr period to use existing stock. The ramifications for other jurisdictions (such as Canada) are unclear. Famphur and Other Livestock Topical Insecti- cides. The problem with magpies being poisoned by topically-applied insecticides in cattle have been known since the early 1970s. The potential for secondary poisoning of raptors was demon- strated in the ear ly-mid-1 980s. Veterinary prod- ucts with a systemic mode of action, such as war- ble insecticides, are registered under the Food, Drug and Cosmetic Act in the U.S. The FDA ac- knowledges the risk of raptor poisoning. Its cur- rent recommendation to users of famphur is to bury carcasses of magpies and other species killed by the product in order to prevent scavenging. The practicality of such a measure, especially with free-ranging cattle, is not discussed. The legality of disposing of protected Migratory Bird species in this fashion is also questionable. Replacing top- ically-applied products by a food ‘pre-mix’ will not resolve the problem. This leaves intubation or in- jection as a safer way of treating cattle. Ideally, products of lower avian toxicity should be consid- ered for topical applications. 26 Mineau et al. VoL. 33, No. 1 Table 14. Summary of North American studies investigating causes of raptor mortality. All are based on receipts of birds at veterinary and/ or rehabilitation facilities. Species Location Period No. Birds Received Nature of Diagnostics Red-tailed Hawk^ U.S. 1975-92 163 AChE measurement when indicat- ed by circumstances. Residues if AChE positive. Bald Eagle^ U.S. -1965-95 >4300 No screening for ChE before mid- 1980s. When indicated by cir- cumstances. 5 species‘s Illinois 1985-87 105 Great Horned Owl** U.S. 1975-93 32 AChE measurement when indicat- ed by circumstances. Residues if AChE positive. Barn Owl and Pueo*^ Hawaii 1992-94 81 B.O. 5 Pueo AChE measurement when indicat- ed. 13 species hawks and owls^ Iowa 1986-87 60 Clinical diagnosis only. Organo- phosphate intoxication suspected but not confirmed. 43 raptors® Central Valley, California not specified 43 Blood and brain ChE measure- ments. Foot residues. Bald Eagle** Fraser Delta, British Columbia 1990-95 84 Plasma and brain ChE tested in all birds where sample available. Residue determination of stom- ach/crop contents when pesti- cides suspected. Bald Eagles** Other areas of British Columbia 1990-95 217 Plasma and brain ChE tested in all birds where sample available. Residue determination of stom- ach/crop contents when pesti- cides suspected. Bald Eagles** Fraser Delta, British Columbia 1996-97 20 Plasma and brain ChE tested in all birds where sample available. Residue determination of stom- ach/ crop contents when pesti- cides suspected. Bald Eagles** Other areas of British Columbia 1996-97 75 Plasma and brain ChE tested in all birds where sample available. Residue determination of stom- ach/ crop contents when pesti- cides suspected. Red-tailed Hawks* Virginia 1985-90 178 Blood ChE. Exposure inferred from discontinuous (bimodal) distribution of activity levels and strong correlation between re- duced levels and symptoms of in- toxication, ataxia being the most common. No chemical confirma- tion. March 1999 Pesticide Poisoning of Raptors 27 Table 14. Extended. % Positive FOR Exposure TO ChE Inhibitors Comments 12% 3% Impact trauma most frequent cause of death. 6% 3% Only 22 AChE tests carried out. 0% AChE tests on 17 B.O. and 3 Pueo. 3% 74% Principally Red-tailed Hawks. 39-40% Range reflects two criteria for ex- posure (plasma ChE reduced by 50% or 2 SD below the mean). 6.0-20% Range reflects two criteria for ex- posure (plasma ChE reduced by 50% or 2 SD below the mean). 10-15% Reduction relative to 1990-95 may reflect selective removal of more toxic alternatives. 6.7-17% 16% Known uses of granular carbofuran in vicinity. Higher numbers in the winter season as seen by Elli- ott et al. 1996, 1997. Several ChE-inhibiting products are used on and around livestock. In the U.S., for example, they in- clude such potentially toxic compounds as cou- maphos, dichlorvos, phosmet, diazinon and tetra- chlorvinfos as well as fenthion and famphur. A review of the potential for exposure and intoxica- tion in raptors and other species is clearly war- ranted. Granular Insecticides. Although secondary poi- soning of raptors resulting from liquid appli- cations of pesticides appeared to be restricted to extremely toxic products (e.g., carbofuran, para- thion, monocrotophos, fenthion), granular for- mulations delivered the insecticide in such a high concentration that a broader selection of prod- ucts resulted in toxicity to scavenging birds of prey. A good example is the series of Bald Eagle and Red-tailed Hawk poisonings in the Fraser Val- ley of British Columbia, Canada. Kills were ini- tially seen with the extremely toxic carbofuran and fensulfothion (Mineau 1993, Elliott et al. 1996). Then came a number of phorate incidents (Elliott et al. 1997) when farmers switched to that granular product. When phorate was voluntarily withdrawn by the manufacturer, incidents involv- ing terbufos and then fonofos were recorded (Ta- bles 4, 8). This indicated that, under the partic- ular conditions, the answer is to be found in products of much lower acute toxicity (probably nonChE-inhibiting insecticides) , nongranular for- mulations or nonpesticidal control strategies. Whereas modifying the granule base may meet with some success in reducing kills of songbirds and other species actively seeking pesticide gran- ules, it will not solve that particular problem which has at its root the ‘passive’ taking of pesti- cide granules from puddles and flooded field ar- eas. Conclusions The loss of birds of prey to ChE-inhibiting pes- ticides is real and can be significant. The more we look for evidence, the more we find. Whether or not current levels of mortality from labeled uses of pesticides are high enough to affect local popula- tions is less important than the fact that most of this mortality is easily preventable. A few regulatory actions in North America would be sufficient to solve most problems. Both in North America and Europe, more education and enforcement are needed to prevent pesticide abuse. Recommendations for Future Research and 28 Mineau et al. VoL. 33, No. 1 Table 14. Continued. Species Location Period No. Birds Received Nature of Diagnostics Bald Eagle' Virginia 1985-90 14 Blood ChE. Exposure inferred from discontinuous (bimodal) distribution of activity levels and strong correlation between re- duced levels and symptoms of in- toxication, ataxia being the most common. No chemical confirma- tion. Great Horned Owl' Virginia 1985-90 21 Blood ChE. Exposure inferred from discontinuous (bimodal) distribution of activity levels and strong correlation between re- duced levels and symptoms of in- toxication, ataxia being the most common. No chemical confirma- tion. Turkey Vulture' Virginia 1985-90 21 Blood ChE. Exposure inferred from discontinuous (bimodal) distribution of activity levels and strong correlation between re- duced levels and symptoms of in- toxication, ataxia being the most common. No chemical confirma- tion. •* Franson et al. (1996). Franson et al. (1995). ‘ Gremillion-Smith and Woolf (1993). “^Franson and Little (1996). Work and Flale (1996). ^Fix and Barrows (1990). s Flosea pers. comm. L.K. Wilson pers. comm. ‘ S L. Porter pers. comm. Monitoring. The value of collecting and making data available on incidents is critical for the cred- ibility of any pesticide-regulatory system. Unfortu- nately, very few jurisdictions are currently assem- bling this information, let alone providing the resources needed for adequate investigation. Also critical is the regulatory system’s ability or willing- ness to respond to problems that are identified. A recent success has been the Argentine govern- ment’s willingness to take rapid action on mono- crotophos. This is in contrast to the slow pace of regulatory action on problem chemicals such as carbofuran, famphur and fenthion in North Amer- ica. Also, the recent monocrotophos incidents re- inforced the interconnectedness of countries and indicated that we should not become complacent about products that have been canceled or other- wise regulated or which may never have been reg- istered in North America or Europe. Many of these products continue to be used heavily in developing countries. The biggest problem we encountered in prepar- ing this assessment was the lack of detail supplied with many incidents. It is critical that all available data be made available to researchers and analysts to allow meaningful conclusions to be drawn con- March 1999 Pesticide Poisoning of Raptors 29 Table 14. Extended. Continued. % Positive FOR Exposure to ChE Inhibitors Comments 43% Known uses of granular carbofuran in vicinity. Higher numbers in the winter season as seen by Elli- ott et al. 1996, 1997. 24% Known uses of granular carbofuran in vicinity. Higher numbers in the winter season as seen by Elli- ott et al. 1996, 1997. 5% Known uses of granular carbofuran in vicinity. Higher numbers in the winter season as seen by Elli- ott et al. 1996, 1997. cerning pesticide incidents. An example of a valuable step forward is the training program on pesticide-poisoning incidents now given to enforce- ment agents and other investigators in the USFWS as well as efforts by the USEPA to collate this in- formation and make it available for regulatory re- views. Making investigators aware of the relevant questions has resulted in a net improvement in the data collected and the quality of the investigations. Accounts of incidents should provide as many de- tails as are necessary for a clear interpretation. This is especially warranted for cases that result from labeled uses or where circumstances are less clear. If incidents are thought to have resulted from abuse, or from a poor or sloppy use of the product, this should be described in detail. A good model for incident reporting can be found in ASTM (1997). Potentially the most valuable piece of informa- tion but the one most often neglected is a thor- ough analysis of the gut contents in carcasses. Also, it is important for investigations to be as open as possible to new diagnoses because they can lead to surprising results. Cases involving famphur are a good example. Famphur cases were routinely thought to be abuse cases until the presence of residues on cow hair for >100 d were demonstrat- ed, and it was documented that magpies ingested the hair. Similarly, full investigation of a disulfoton incident demonstrated that kills can result from plant-assimilated seed-treatment pesticides. Littrell (1988) investigated a number of kills from carbof- uran granules in rice involving waterfowl as well as Red-tailed Hawks and a Northern Harrier. Because some of these kills occurred in autumn (outside of the usual season), he suspected abuse or serious misuse. However, the lengthy persistence of these granules was demonstrated (Elliott et al. 1996, Wil- son unpubl.) showing that incidents in rice fields should now be considered in a new light. The other major improvement needed is to in- crease the number of birds routinely screened for ChE inhibitors (Porter 1993, Smith et al. 1995). The proportion of birds found to be exposed (ei- ther lethally or sublethally) is dramatically higher in those situations where large numbers of birds coming into rehabilitation centers are assayed re- gardless of the initial diagnosis (Table 14). The link between sublethal impairment and other caus- es of mortality such as electrocution or impact strikes has been made often enough that this should be considered a possibility in any case in- vestigation. ChE determinations, although not foolproof, are inexpensive and easy to perform. Automated analysis systems (e.g., Kodak Ekta- chem® system) field kits with battery-operated spectrophotometers [e.g., EQM Research Inc.]) or improvements that allow the collection of blood on filter paper without need for refrigeration (Tru- deau et al. 1995) puts the technique within easy reach of anyone. Acknowledgments This review could not have been written without the many individuals and agencies who submitted data in the form of unpublished cases of wildlife poisoning. The sim- ple tabular tally of incidents or the abbreviation pers comm, often hides many hours or days of careful inves- tigation on the part of these dedicated individuals. We hope that this review will be an encouragement for them to continue. We also thank J.A. Duffe, D.A. Kirk, J. Ja- quette and the Sierra Legal Defense Fund for their help in compiling the information. 30 Mineau et al. VoL. 33, No. 1 Table 15. Philogenic summary of documented cases of avian mortality in North America with the insecticide car- bofuran (granular formulations) when used according to label instructions. Order Family or Subfamily Common Name No. Species Killed Ciconiiformes Ardeidae waders 1 Anseriformes Anatidae waterfowl 12 Gruiformes Rallidae rails 1 Charadriiformes Charadriidae shorebirds 7 Laridae gulls 3 Falconiformes Accipitridae hawks and eagles 5 Falconidae falcons 1 Galliformes Phasianidae grouse 3 Columbiformes Columbidae doves 2 Strigiformes Strigidae owls 2 Passeriformes Tyrannidae tyrant flycatchers 2 Alaudidae larks 1 Hirundinidae swallows 1 Corvidae jays 3 Muscicapidae old world warblers and thrushes 5 Laniidae shrikes 1 Mimidae mimic thrushes 2 Motacillidae pipits 1 Troglodytidae wrens 1 Bombycillidae waxwings 1 Sturnidae starlings 1 Emberizidae-Parulinae new world warblers 3 Emberizidae-Thraupinae tanagers 1 Emberizidae-Cardinalinae buntings 3 Emberizidae-Emberizinae sparrows 13 Emberizidae-Icterinae blackbirds 9 Fringillidae finches 2 Passeridae weaver finches 2 Total 89 Sources: USFWS, USEPA, and CWS unpublished. Literature Cited Allen, G.T., J.K. Veatch, R.K. 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Raptors Family Common Name Scientific Name Accipitridae Cooper’s Hawk Accipiter cooperii Accipitridae Goshawk Accipiter gentilis Accipitridae Eurasian Sparrowhawk Accipiter nisus Accipitridae Sharp-shinned Hawk Accipiter striatus Accipitridae Eurasian Black Vultures Aegypius monachus Accipitridae Golden Eagle Aquila chrysaetos Accipitridae Greater Spotted Eagle Aquila clanga Accipitridae Imperial Eagle Aquila heliaca Accipitridae Steppe Eagle Aquila nipalensis Accipitridae Lesser Spotted Eagle Aquila pomarina Accipitridae Tawny Eagle Aquila rapax Accipitridae Wahlberg’s Eagle Aquila wahlbergi Accipitridae Eurasian Eagle Owl Bubo bubo Accipitridae Cape Eagle Owl Bubo capensis Accipitridae Verreaux’s Eagle Owl Bubo lacteus Accipitridae Augur Buzzard Buteo augur Accipitridae Common Buzzard Buteo buteo Accipitridae Red-tailed Hawk Buteo jamaicensis Accipitridae Rough-legged Hawk Buteo lagopus Accipitridae Red-shouldered Hawk Buteo lineatus Accipitridae Ferruginous Hawk Buteo regalis Accipitridae Long-legged Buzzard Buteo rufinus Accipitridae Swainson’s Hawk Buteo swainsoni Accipitridae Swallow-tailed Kite Chelictinia riocourii Accipitridae Western Marsh Harrier Circus aeruginosus Accipitridae Pacific Marsh Harrier Circus approximans Accipitridae Hen (Northern) Harrier Circus cyaneus Accipitridae Pallid Harrier Circus macrourus Accipitridae Black-shouldered Kite Elanus caeruleus Accipitridae White-tailed Kite Elanus leucurus Accipitridae White-tailed (Sea) Eagle Haliaeetus albicilla Accipitridae Bald Eagle Haliaeetus leucocephalus Accipitridae Booted Eagle Hieraaetus pennatus Accipitridae Mississippi Kite Ictinia mississippiensis Accipitridae Lizard Buzzard Kaupifalco monogrammicus Accipitridae Pale Chanting-Goshawk Melierax canorus Accipitridae Gabar Goshawk Micronisus gabar Accipitridae Black Kite (European) Milvus migrans migrans Accipitridae Yellowbilled Kite (African Black Kite) Milvus migrans parasitus Accipitridae Red Kite Milvus milvus Accipitridae Bateleur Eagle Terathopius ecaudatus Cathartidae Black Vulture Coragyps atratus Cathartidae Turkey Vulture Cathartes aura Falconidae Merlin Falco columbarius Falconidae Prairie Falcon Falco ynexicanus Falconidae Peregrine Falcon Falco peregrinus Falconidae American Kestrel Falco sparverius Falconidae Gommon Kestrel Falco tinnunculus Falconidae Pygmy Falcon Polihierax semitorquatus Pandionidae Osprey Pandion haliaetus Sagittariidae Secretary-bird Sagittarius serpentarius Stngidae Short-eared Owl Asio flammeus March 1999 Pesticide Poisoning of Raptors 37 Appendix 1. Continued. Raptors Family Common Name Scientific Name Strigidae Long-eared Owl Agio otus Strigidae Burrowing Owl Athene cunicularia Strigidae Little Owl Athene noctua Strigidae Great Horned Owl Bubo virginianus Strigidae Pearl-spotted Owlet Glaucidium perlatum Strigidae Snowy Owl Nyctea scandiaca Strigidae Eastern Screech-Owl Otus asio Strigidae Tawny Owl Strix aluco Strigidae Barred Owl Strix varia Tytonidae Barn Owl Tyto alba Non-Raptors Greylag Goose Anser anser Pink-footed Goose Anser brachyrhynchus Wood-pigeon Columba palumbus Starling Sturnus vulgaris House Sparrow Passer domesticus Rock Dove Columba livia Eared Dove Zenaida auriculata Black-billed Magpie Pica pica European Robin Erithacus rubecula American Robin Turdus migratarius Mourning Dove Zenaida macroura Red-billed Quelea Quelea quelea Barn Swallow Hirundo rustica Dunnock Prunella modularis Grackles Quiscalus spp. J Raptor Res. 33(1) :38 © 1999 The Raptor Research Foundation, Inc. SOLVING RAPTOR-HUMAN CONFLICTS Robert E. Kenward Institute of Terrestrial Ecology, Furzebrook Research Station, Wareham, Dorset BH20 3 AS, U.K. The eight expanded abstracts that follow are from papers presented in a symposium on “Solving Raptor/Human Conflicts” at the 1993 European conference of Raptor Research Foundation, Inc. in Canterbury, U.K. The aim was to take stock of cur- rent information on contentious issues involving raptors, to indicate where more information was needed, and to prepare a Position Statement that would encourage bridge-building between raptor interests and groups inconvenienced by raptors. The Raptor Research Foundation, Inc. thanks the authors, the referees of these publications and the many people who contributed toward the Position Statement, which is published separately. The first of these papers was cowritten by Mike Kochert and the late Butch Olendorff, summariz- ing the prolonged contribution that Butch made to saving raptors and utility companies from the problems that can arise when raptors perch or nest on powerlines. It is complemented by two publi- cations from related studies in Europe and Africa. A second pair of papers describes pioneering work being done in the U.S. to predict and avoid colli- sions between large raptors and aircraft. It pre- cedes a consideration of how to handle raptor at- tacks on humans, and the last two abstracts describe problems and solutions from studies of raptor predation on game and livestock. One pa- per was withdrawn from the proceedings because the research has moved forward rapidly and is be- ing published elsewhere. This is a continuing study of the impact of predation by Hen Harriers ( Circus cyaneus) and Peregrine Falcons {Falco peregrinus) on Red Grouse {Lagopus lagopus) in Scotland (Red- path and Thirgood 1997, Thirgood and Redpath 1997, in press a, b). Large areas of moorland, maintained primarily for shooting grouse, support an interesting assemblage of wildlife, including sev- eral raptor species. Following the cessation of ille- gal raptor control in the main study area, harrier numbers increased from two breeding females in 1992 to 20 pairs in 1997, with peregrine pairs dou- bling from three to six. Raptor predation was large- ly additive and could remove 50% of the grouse population between spring and autumn, with har- riers having the greatest impact when grouse stocks were low. On the study moor, the predation re- duced grouse numbers far below those on neigh- boring moors without full protection of raptors. The stocks were then too low to be managed eco- nomically for shooting, thereby motivating alter- native land uses such as forestry or sheep grazing, which destroy the heather system. There is an ur- gent need to find an acceptable way between the present widespread illegal control of harriers (Eth- eridge et al. 1997) and the loss of habitats on which the grouse and harriers depend. Literature Cited Etheridge, B., R.W. Summers and R. Green. 1997. The effects of illegal killing and destruction of nests on the population dynamics of Hen Harriers in Scotland. J. Appl. Ecol. 34:1081-1106. Redpath, S.M. and SJ. Thirgood. 1997. Birds of prey and Red Grouse. The Stationary Office, London, U.K. Thirgood, S.J. and S.M. Redpath. 1997. Red Grouse and their predators. Nature 389:330-331. AND . Raptor and grouse: a conflict in the uplands. Proceedings of the 5th Global Conference of the World Working Group on Birds of Prey and Owls. Berlin, Germany. In press, a. AND . Can raptor predation limit Red Grouse populations? Proceedings of the 23rd Inter- national Ornithological Congress. Durban, South Af- rica. In press, b. 38 J. Raptor Res. 33(1) : 39-42 © 1999 The Raptor Research Foundation, Inc. CREATING RAPTOR BENEFITS FROM POWERLINE PROBLEMS Michael N. Kochert^ and Richard R. Olendorff^ U.S. Bureau of Land Management, Raptor Research and Technical Center, 3948 Development Avenue, Boise, ID 83705 U.S. A. Powerlines benefit raptors by providing en- hanced nesting and roosting sites. However, they also can kill raptors by electrocution and raptors can interfere with power transmission. The electro- cution problem has been reduced by correcting ex- isting lethal lines and implementing electrocution- safe designs for new lines. Remedial actions include pole modifications, perch management and insulation of wires and hardware. New line de- signs provide for proper insulation and adequate spacing of conductors and grounded hardware. Nesting platforms can reduce power transmission problems and enhance the benefits of nesting on powerlines. A combination of perch deterrents and insulator shields is a positive, cost-effective ap- proach to managing bird contamination that al- lows birds to continue roosting on the towers. Problems Affecting Raptors Powerlines benefit raptors by providing en- hanced perch sites for hunting (Olendorff et al. 1981). However, they can also adversely affect rap- tors (Olendorff et al. 1981, Williams and Colson 1989). In the U.S., raptor collisions with or entan- glements in powerlines or tower lattices are not m^or problems (Olendorff et al. 1981, Olendorff and Lehman 1986) and shooting of raptors on util- ity poles appears to be less of a problem than elec- trocution (Peacock 1980, Benson 1982, APLIC 1996). A raptor electrocution problem became appar- ent in the U.S. in 1971 (Olendorff et al. 1981). Concern stimulated testing of powerline designs that were safe for raptors (Nelson and Nelson 1977). This work culminated in the three editions of “Suggested Practices for Raptor Protection on Power Lines” (Miller et al. 1975, Olendorff et al. 1981, APLIC 1996) which provide guidelines for managing the electrocution problems. 1 Present address: USGS Forest and Rangeland Ecosystem Science Center, Snake River Field Station, 970 Lusk St., Boise, ID 83706 U.S.A. ^ Deceased. At least 17 species of raptors have been electro- cuted in the U.S. (Williams and Colson 1989). Large raptors are more susceptible to electrocu- tion because they more easily span the distance be- tween energized wires (Olendorff et al. 1981). Golden Eagles {Aquila chrysaetos) bave been the most commonly electrocuted raptor, and most are subadults (Boeker and Nickerson 1975, Olendorff et al. 1981, Benson 1982, APLIC 1996, BLM, un- publ. data). The susceptibility of young eagles to electrocution may be due to their inexperience in flight (Nelson and Nelson 1977, Olendorff et al. 1981). Most Golden Eagle electrocutions appar- ently occur in winter (Benson 1982, PacifiCorp, unpubl. data) . Inclement weather (rain, snow and wind) during winter increases the susceptibility of raptors to electrocution because of reduced flight maneuverability and increased conductivity of wet feathers (Olendorff et al. 1981). The electrocution problem is more acute in grass and shrublands of the western U.S. and in areas where natural perches are scarce (Boeker and Nickerson 1975, Benson 1982, APLIC 1996). In the U.S., electrocutions are more prevalent on distribution lines (^69 kV) than on high voltage transmission lines (Boeker and Nickerson 1975, APLIC 1996). Raptors are rarely electrocuted on transmission lines or low voltage lines (<1 kV, AP- LIC 1996) . Powerpole configuration influences the proba- bility of raptor electrocution more than voltage alone (Williams and Colson 1989). Lethal config- urations usually do not have adequate spacing be- tween the phase conductors and ground wires or grounded hardware to prevent large raptors from touching them (Olendorff et al. 1981). Poles with additional hardware (i.e., transformers, switches, jumpers, other extra wires) are also lethal (Olen- dorff et al. 1981) . Certain powerpoles are preferred by eagles and have a greater probability of electrocuting birds (Nelson and Nelson 1977, Olendorff et al. 1981, Benson 1981, 1982). “Preferred” poles are either more elevated above the surrounding terrain or in 39 40 Expanded Abstracts VoL. 33, No. 1 areas with higher prey densities (Benson 1981). Pole arms that are diagonal or parallel to the pre- vailing winds tend to have a higher incidence of electrocutions (Nelson and Nelson 1977, Benson 1981, 1982). Alleviation of the electrocution problem involves correcting existing lethal lines (pole modifications, perch management and insulation) and imple- menting new line designs that are safe for raptors. Objectives of these improvements are to provide adequate separation between energized wires and hardware and adequate insulation of wires and hardware where sufficient separation cannot be ob- tained. Modifying every pole along a line is cost- prohibitive and perhaps unwarranted from a bio- logical prospective (Williams and Colson 1989, APLIC 1996). Action should focus on identifying and correcting chronically lethal poles (i.e., “pre- ferred poles”) and monitoring the success of the remedial action. Nelson and Nelson (1977) felt that most electrocutions could be prevented by correcting only about 2% of the poles. The three-phase single-pole construction with a crossarm has been associated with most electrocu- tions (Olendorff et al. 1981, APLIC 1996). Meth- ods to modify problem poles involve increasing conductor spacing and include (1) raising the cen- ter phase, (2) lowering the crossarm, (3) suspend- ing the outer phases below the crossarm and (4) placing longer crossarms on the pole. The objec- tive of these methods is to provide at least 152 cm separation between conductors (Olendorff et al. 1981, APLIC 1996). The next most lethal configuration is a single- phase line with the conductor on top of the pole and a ground wire near the top insulator (Olen- dorff et al. 1981). The problem was solved by low- ering the pole ground wire at least 30 cm below the top of the pole or cutting 10 cm gaps in the ground wires (Olendorff et al. 1981, APLIC 1996). Elevated perches place birds above any danger and perch guards discourage raptors from perch- ing on dangerous parts of powerpoles (Olendorff et al. 1981, APLIC 1996). They are used when ad- equate separation of wires and hardware cannot be obtained or when pole modification is infeasible. Perch guards are often used in conjunction with elevated perches. Wires and other hardware are insulated on poles with wires connecting transformers and other pieces of equipment or when modifying poles is impractical (Olendorff et al. 1981, APLIC 1996). Insulation is often used in conjunction with elevat- ed perches and is an economical option when only a few poles need modification (APLIC 1996). The armless design is effective in minimizing raptor electrocutions provided there is adequate spacing (152 cm) between wires and hardware (APLIC 1996). This design is more expensive than the conventional crossarm designs, and it creates extra hazards to line crews (Olendorff et al. 1981) . Certain 69-kV armless configurations once be- lieved to be raptor-safe were recently found to be lethal to eagles due to grounding problems (AP- LIC 1996). The problem was resolved by placing perch guards on the top of the insulators or re- placing insulator posts with longer ones (Pacifi- Corp, pers. comm.). Single-phase configurations should leave the top 50-75 cm of the pole free of wires or other hardware (APLIC 1996). Three- phase designs should provide adequate conductor spacing (152 cm) by using a taller pole and lower placement of the crossarm (APLIC 1996). Underground construction is an obvious solu- tion to the raptor electrocution problem. Although this practice is used in Europe and in urban areas of the U.S., it is considered too expensive for wide- spread application in rural areas of the U.S. (AP- LIC 1996). Underground lines also occasionally present design problems, particularly for high volt- age transmission lines (APLIC 1996). Nelson (1982) felt that the raptor electrocution problem in the U.S. had been reduced in the 1970s through cooperative efforts of government agen- cies, conservation organizations and the electric in- dustry. It is debatable, however, whether electro- cutions have decreased in recent years (APLIC 1996). However, awareness of the issue and efforts to resolve it have increased, and raptor electrocu- tions have decreased in areas where powerlines have been modified. Electrocution still occurs in the U.S., and it is a major problem in certain areas (APLIC 1996). Resolving electrocution problems is a continuing cooperative effort between the utili- ties and the regulatory agencies involving an “in- tegrated management approach” (APLIC 1996). In this approach agencies and utility companies formally agree to action guidelines and standard operating procedures to identify and rectify prob- lems. Power Transmission Problems Powerlines benefit raptors and other large birds by providing enhanced nesting and roosting sites March 1999 Expanded Abstracts 41 (Engel et al. 1992, Steenhof et al. 1993). The ben- efits to nesting raptors are compromised by prob- lems associated with power outages from nesting material, feces or electrocuted birds (Williams and Colson 1989, APLIC 1996). Roosting and perching birds can cause power outages where their fecal matter contaminates insulators (Michner 1928, Kaiser 1970, Sierra Pacific Power et al. 1988). The traditional solution to the problem was to remove nests (Stocek 1981). This is not a desirable solution because of legal and political ramifications (Olen- dorff et al. 1981), It is also ineffective because birds will often rebuild nests on the same or a nearby structure (Stocek 1981, Steenhof et al. 1993). An- other approach is to discourage nesting, which is often used in conjunction with other efforts to en- hance nesting opportunities (Stocek 1981, Wil- liams and Colson 1989, APLIC 1996). Nesting opportunities can be enhanced by relo- cating nests, modifying powerpoles and providing nesting platforms on the powerline structures (Sto- cek 1981, APLIC 1996) . Relocating nests from pow- erlines to nearby trees or nesting platforms has been successful for Ospreys {Pandion haliaetus)\ however, sometimes birds will nest on another structure on the line (Stocek 1981, Austin-Smith and Rhodenizer 1983). Pole modifications (lower- ing crossarms, wires and hardware so birds can safely nest on top of the pole) are apparently ef- fective but costly (Stocek 1981). The alternative to pole modifications is to place the nest on a plat- form and raise it safely above the wires (APLIC 1996). Although nest platforms have been used on pow- erlines since the 1940s, few quantitative studies as- sessed their overall effectiveness (Olendorff et al. 1981). A 9-yr study on a new 500-kV transmission line in Idaho and Oregon by Steenhof et al. (1993) found that Golden Eagles and Ferruginous Hawks {Buteo regalis) apparently preferred the nesting platforms and had higher success rates on plat- forms, Raptor and Common Raven (Corvus corax) nesting success on transmission line towers was similar to, or higher than, that on surrounding nat- ural substrates. In some cases, towers provided a more secure nesting substrate. The transmission line provided an opportunity for raptors and ra- vens to nest in areas where they had not before. The line was likely responsible for an overall in- crease in the number of breeding pairs, Steenhof et al. (1993) recommended that utility companies use platforms or tower modifications to safely at- tract raptors to specific towers or positions on tow- ers and to enhance raptor productivity, and that nest removal was ineffective and unnecessary. Historically, the approach to resolving problems associated with roosting raptors was either to deter birds from roosting over insulators or to shield the insulators from fecal contamination (Michner 1928). A comprehensive study in Idaho showed that the combination of shields and pegging can be a positive and cost-effective approach to man- aging bird contamination of insulators on high- voltage transmission lines (Young and Engel 1988, Engel et al. 1993). Although this study focused on Common Ravens, results may have application to raptors (vultures) that roost communally on pow- erline structures. Shields successfully protected central-string insulators from raven fecal contami- nation, and pegging effectively deterred ravens from roosting on outer portions of the tower cross- arms, Treatments did not repel ravens from roost- ing on traditional towers, and they did not move to other towers. The effort significantly reduced bird-powerline problems but allowed birds to con- tinue to roost on the towers. Literature Cited Austin-Smith, PJ- AND G. Rhodenizer. 1983. Ospreys, Pandion haliaetus. Can. Field Nat. 97:315-319. Avian Powerline Interaction Committee (APLIC). 1996. Suggested practices for raptor protection on powerlines: the state of the art 1996. Edison Electric Institute/Raptor Research Foundation, Washington, DC U.S.A. Benson, P.C. 1981. Large raptor electrocution and pow- erpole utilization: a study in six western states. Ph.D dissertation, Brigham Young University, Provo, UT U.S.A. . 1982. Prevention of Golden Eagle electrocution. EA-2680 Res. Proj. 1002, Final Rep. Electric Power Res. Inst. Palo Alto, CA U.S.A. Boeker, E.L. and P.R. Nickerson. 1975. Raptor electro- cutions. Wildl. Soc. Bull. 3:79-81. Engel, K.A., L.S. Young, K. Steenhof and M.N. Ko- chert. 1992. Communal roosting of Common Ravens in southwestern Idaho. Wilson Bull. 104:105-121. , L.S. Young, J. A. Roppe, C.P. Wright and M. Mul- rooney. 1993. Controlling raven fecal contamination of transmission line insulators. Pages 10-14 in J.W. Huchabee [Ed.], Proc. Int. Workshop on Avian Inter- actions with Utility Structures. Electric Power Res. Inst. Palo Alto, CA U.S.A. Kaiser, G. 1970. The buzzard (Buteo) as a cause of single pole breakdowns in high-tension lines. Elektrotechnische Zietschrift — ^A. 91:313—317. 42 Expanded Abstracts VoL. 33, No. 1 Michner, H. 1928. Where engineer and ornithologist meet: transmission line troubles caused by birds. Con- dor 50:169-175. Miller, A.D., E.L. Boeker, R.S. Thorsell and R.R. Glendorff. 1975. Suggested practices for raptor elec- trocution on powerlines. Raptor Research Founda- tion, Inc., Provo, UT U.S.A. Nelson, M.W. 1982. Human impacts on Golden Eagles: a positive outlook for the 1980s and 1990s. Raptor Res. 16:97-103. AND P. Nelson. 1977. Powerlines and birds of prey. Pages 228-242 in R.D. Chancellor [Ed.], Proc. ICBP World Gonf. on Birds of Prey. International Council for Bird Preservation, Cambridge, U.K. Glendorff, R.R., A.D. Miller and R.N. Lehman. 1981. Suggested practices for raptor protection on power- lines — the state-of-the-art in 1981. Raptor Res. Rep. No. 4, Washington, DC U.S.A. and R.N. Lehman. 1986. Raptor collisions with util- ity lines: an analysis using subjective field observations. Pacific Gas and Electric Co., San Ramon, CA U.S.A. Peacock, E. 1980. Powerline electrocution of raptors. Pages 2-5 in R.P. Howard and J.F. Gore [Eds.], Pro- ceedings of a workshop on raptors and energy devel- opments. USDI, Fish and Wildl. Serv., Boise, ID U.S.A. Sierra Pacific Power, Bonneville Power Administra- tion, Pacific Power and Light and Idaho Power 1988. A joint utility investigation of unexplained trans- mission line outages. Electric Power Res. Inst. Final Rep. 5735, Palo Alto, CA U.S.A. Steenhof, K., M.N. Kochert and J.A. Roppe. 1993. Nest- ing by raptors and ravens on electrical transmission line towers./. Wildl. Manage. 57:271-281. Stocek, R.F. 1981. Bird related problems on electric pow- er systems in Canada. Can. Electrical Assoc. Final Rep. Contract No. 110 T210, Montreal, Quebec Canada. Williams, R.W. and E.W. Colson. 1989. Raptor associa- tions with linear rights-of-way. Pages 173-192 in Proc. Western Raptor Management Symposium and Work- shop. Natl. Wildl. Fed., Washington, DC U.S.A. Young, L.S. and K.A. Engel. 1988. Implications of com- munal roosting by Common Ravens to operation and maintenance of Pacific Power and Light Company’s Malin to Midpoint 500 Kv transmission line. Final Res Rep., Pacific Power and Light Co., Portland, GR U.S.A. J Raptor Res. 33(l):43-48 © 1999 The Raptor Research Foundation, Inc. PREVENTING BIRDS OF PREY PROBLEMS AT TRANSMISSION LINES IN WESTERN EUROPE Patrick Bayle 15 rue Bravet, 13005 Marseille, France Among the 37 species of birds of prey (28 fal- coniforms and 9 strigiforms) that breed or winter regularly in western Europe, at least 30 (24 falcon- iforms and 6 strigiforms) have been killed on pow- erlines, either through electrocutions or, to a lesser extent, through collisions with electric wires. Mor- tality on medium voltage distribution lines plays an important role in the global mortality of certain eagles, especially among juveniles (e.g., Spanish Imperial Eagle ^Aquila (heliaca) adalbertz] in Spain and Bonelli’s Eagle [Hieraaetus fasciatus] in Spain and southern France) and is responsible for the general decline of these species. Powerlines also have an important impact on some common birds of prey, both regionally (e.g., Eurasian Eagle Owl [Bubo bubo in the southern French Alps) and lo- cally (e.g., Eurasian Kestrel [Falco tinnunculus] in different areas in France). Different devices have been developed to assure a better isolation be- tween electric wires and pylons and to prevent birds from perching on electric poles, but the most efficient protection is to bury the lines. Countries such the Netherlands (which have already achieved this aim), Belgium, Germany and the U.K. now intend to bury all their medium voltage lines. Birds of Prey vs. Powerlines in Western Europe One of the m^or factors causing declines in rap- tor populations is pollution, but forms of distur- bance such as habitat loss and persecution have adverse effects on raptors (Newton 1979, Gensboel 1984). Accidental deaths that come to notice usu- ally involve collisions of raptors with vehicles, buildings and other structures (Newton 1979). One of the human causes of mortality, which has been overlooked in Europe, is the powerline web with which raptors collide or electrocute them- selves. For certain species, collisions and electro- cutions on overhead wires form a major part of the total mortality and in extreme cases they may have contributed to raptor declines. This type of mor- tality is a major threat for species such as Bonelli’s (Real et al. 1996) and Spanish Imperial Eagles (Ferrer and Hiraldo 1990). Investigations in Germany, France and Spain show that, among the 37 species of raptors that breed or winter regularly in western Europe, at least 30 species have been victims of powerlines (Table 1). Raptors most often found dead under powerlines are common species such as Common Buzzards (Buteo buteo), Black Kites {Milvus migrans) and Eurasian Kestrels. Medium voltage powerlines (1-60 kV) are re- sponsible for most of the raptor mortalities on electric lines. In France, 96.5% of 649 birds of prey found dead under transmission lines were under medium voltage powerlines (Seriot and Rocamora 1992) . The low impact of high or very high voltage powerlines (60->150 kV) on raptors is illustrated by studies of the avian mortality on portions of such lines in the Netherlands (Heijnis 1980), Ger- many (Hoerschelmann et al. 1988), France (Bayle and Iborra unpubl. data) and Italy which show that birds of prey represent between only 0. 1-0.4% of all birds killed on these lines. In the French study (Seriot and Rocamora 1992), all birds of prey found under high or very high voltage powerlines were killed by collision with transmission lines. Since then an immature Bonelli’s Eagle is known to have died from electrocution on a 63-kV power structure near Marseilles in August 1992 (Cheylan and Bayle unpubl. data) . Of the raptors killed on medium voltage powerlines, 93.5% were electro- cuted and 6.5% collided against electric wires. In France and Spain, the role of powerlines in the general mortality of raptors has been studied recently in species with small populations such as the Spanish Imperial Eagle (Ferrer and Hiraldo 1990), Golden Eagle {Aquila chrysaetos, Gouloumy 1993) , Bonelli’s Eagle (Real et al. 1996) and Grif- fon Vulture {Gyps fulvus, Terrasse et al. 1994). Since this form of mortality affects mainly juvenile birds, it can have an important impact on the pop- ulation dynamics of these species and be critical for their survival. Between 1974-88, 51.5% of 68 43 44 Expanded Abstracts VoL. 33, No. 1 Table 1. Raptor species affected by mortality on electric powerlines in three European countries (Germany, France and Spain). Species E E Osprey {Pandion haliaetus) Common Buzzard {Buteo buteo) -f-f-f C + + A + + Rough-legged Buzzard {Buteo lagopus) -f Honey Buzzard {Pernis apivorus) -t- -t- Black Kite {Milvus migrans) -f + + + A Red Kite {Milvus milvus) -f-f + + Short-toed Eagle ( Circaetus gallicus) -t- -1- Bonelli’s Eagle {Hieraaetus fasciatus) + + Booted Eagle {Hieraaetus pennatus) -f + Golden Eagle {Aquila chrysaetos) -1- + Spanish Imperial Eagle {Aquila {heliaca) adalberti) + Bearded Vulture ( Gypaetus barbatus) -1- European Black Vulture {Aegypius monachus) + Griffon Vulture {Gyps fulvus) -f + Egyptian Vulture {Neophron percnopterus) -t- European Sparrowhawk {Accipiter nisus) -t- Northern Goshawk {Accipiter gentilis) -h -t- -f-f Marsh Harrier {Circus aeruginosus) + Hen Harrier {Circus cyaneus) -1- Montagu’s Harrier {Circus pygargus) -1- Peregrine Falcon {Falco peregrinus) -1- -1- European Hobby {Falco subbuteo) -f -f Merlin {Falco columbarius) -f Eurasian Kestrel {Falco tinnunculus) + + A -f-f-l- -1- Barn Owl {Tyto alba) + -f + -f Eurasian Eagle Owl {Bubo bubo) + + + -1- Long-eared Owl {Asio otus) + + Short-eared Owl {Asio flammeus) + Little Owl {Athene noctua) + -1- Tawny Owl {Strix aluco) + A A + Total number dead under powerlines 567 686 1282 D — Germany (Haas 1980), F — France (Seriot and Rocamora 1992, Niebuhr pers. comm.), E — Spain (Haas 1980, Castano and Guzman 1989, Mugica 1989, Negro and Manez 1989, Ferrer et al. 1991, Agrupacion Naturalista Esparvel 1993 and Segara and Martos 1993). + <5%, ++ 5-10% and + + + >10% of the total number of raptors found dead under powerlines. Spanish Imperial Eagles found dead in Dohana National Park (Spain) were electrocuted. After iso- lation or burial of powerlines in 1987, juvenile sur- vival increased from 17.6% in 1986-87 to 80.0% in 1988—89 (Ferrer and Hiraldo 1990). In northeast- ern Spain (Alicant, Murcia and Catalonia) and southern France (Languedoc-Roussillon and Prov- ence) powerlines were responsible for 44.8% of the known mortalities of Bonelli’s Eagles between 1980-93 {N = 58). The situation varied greatly from one region to another with only 5.2% of the birds found dead in Murcia dying on powerlines as opposed to 38.0% dying on powerlines in Cat- alonia and 82.6% in southern France (Real et al. 1996). In the latter area where the total breeding population is estimated to consist of only 28 pairs, among 20 ringed juveniles found dead between 1990—95, 17 were killed on powerlines (Cheylan et al. 1996). All Bonelli’s Eagle populations in north- eastern Spain and southern France are declining and, in some areas (Alicant and Murcia), the abrupt decrease in population size seems to be a consequence of high adult mortality through di- rect persecution. In other areas (Catalonia and southern France) where adult mortality is lower, the decline has been more moderate and has been March 1999 Expanded Abstracts 45 Table 2. Percent of general avian mortality on electric powerlines in "Important Bird Areas” (IBAs) in the Plain of Crau and its vicinity (Bouches-du-Rhone, southeastern France), 1988—93. Type of Bird A^ B C raptors ( F alconifor mes / Strigiformes) 40.0 14.0 0.2 corvids (Corvidae) 45.0 10.3 0.5 gulls and terns (Laridae) 3.0 15.9 61.6 herons (Ardeidae) 0.0 43.0 0.6 White Stork {Ciconia ciconia) 6.0 0.0 0.0 Greater Flamingo (Phoenicopterus ruber) 0.0 3.7 14.1 other birds 6.0 13.1 23.0 Total {N) 100 107 865 ® A — electrocutions on medium voltage (<60 kV) distribution lines in the Plain of Crau (IBAPAC 03) (Kabouche 1991, Bayle unpubl data). B — electrocutions and collisions on medium voltage distribution lines in the Vigueirat marshes (IBA PAC 08) (Hecker et al 1992, Lucchesi unpubl. data). C — collisions on very high voltage (>150 kV) distribution lines in the saltworks of Fos-sur-Mer (IBA PAC 15) (Bayle unpubl. data). mainly a consequence of habitat destruction and high preadult mortality due to electrocution (Real et al. 1996). Raptors other than eagles and vultures are also affected by powerlines but it is difficult to assess the severity of the mortality since it varies greatly from one population and geographical area to an- other. For example, powerlines were responsible for 22.6% of identified cases of mortality of Eur- asian Eagle Owls in Sweden (Olsson 1979) and Fin- land (Saurola 1979 in Mikkola 1983), 32.5% in Germany (Wickl 1979), 54.7% in France (Bayle 1992 and unpubl. data) and 16.3% in Spain (Her- nandez 1989). In the southern Alps and Mediter- ranean area, the proportion of Eurasian Eagle Owls killed by powerlines varied from 45.5% in the Mediterranean area (N = 66) to 88.9% in the Alps {N = 18). The “electrification” of landscapes seems to be the major limiting factor of the alpine population of Eurasian Eagle Owls and may be the explanation for the decline of the species in the Swiss and French Alps (Haller 1978, Bayle 1992), as well as in the Italian Apennines (Penteriani and Pinchera 1991). Powerlines typically kill the smaller, more com- mon raptors (Table 1). In France, Eurasian Kes- trels are very frequent victims mainly because of massive electrocutions on certain medium voltage lines (Deschamps 1980, Brochet 1993). In one case, 130 kestrels, one European Hobby {Falco sub- buteo ) , four Common Buzzards and 32 other birds were found in four years (1988-91) on a 5-km por- tion of a 20-kV powerline (Brochet 1993). Most powerlines are deadly because the config- uration of structures that support them makes rap- tors vulnerable (Deschamps 1980, Haas 1980, Ser- iot and Rocamora 1992, Ferrer et al. 1993). The problem is magnified when these powerlines tra- verse important raptor areas such as territories with important raptor breeding populations (e.g., near vulture colonies) or terrains which attract large numbers of birds of prey (e.g., hunting grounds such as marshlands or steppes). For ex- ample, significant raptor mortality on medium volt- age lines has been recorded at Donana National Park in Spain (Haas 1980, Ferrer et al. 1991) and in southeastern France near the plain of Crau and its surroundings (marshes to the west and saltworks to the south) . This area in France is a hunting ter- ritory for Short-toed Eagles {Circaetus gallicus) in the postnuptial period, a wintering area for Red Kites (Milvus milvus) and a major part of the ju- venile Bonelli’s Eagles in France use this area. These sites have been classified among the “Im- portant Bird Areas” (IBAs) according to Birdlife International standards (Rocamora 1994). They are also close to densely urbanized and industrial- ized zones with considerable density of electric lines of all types. This has resulted in a significant avian mortality for Black Kites and Short-toed and Bonelli’s Eagles (Tables 2, 3). Preventing Raptor Problems at Transmission Lines Before trying to prevent raptor problems at transmission lines, the first step is to assess the im- pact of powerlines on these birds. This can only be done by conducting thorough surveys under pow- erlines to determine which portions of the network are dangerous for birds of prey. Contacts must then be made with the power 46 Expanded Abstracts VoL. 33, No. 1 Table 3. Raptor mortality on electric powerlines in Im- portant Bird Areas (IBAs) in the Plain of Crau and its vicinity (Bouches-du-Rhone, southeastern France), 1988- 93. Species A^ B c Common Buzzard {Buteo buteo) 5 3 0 Black Kite {Milvus migrans) 15 2 0 Red Kite {Milvus milvus) 1 0 0 Buzzard or kite {Buteo/ Milvus) 3 0 0 Short-toed Eagle ( Circaetus gallicus) 5 5 0 Bonelli’s Eagle {Hieraaetus fasciatus) 4 4 0 Short-toed or Bonelli’s Eagle 1 0 0 European Sparrowhawk {Accipiter nisus) 0 0 1 Eurasian Kestrel {Falco tinnunculus) 3 1 0 unidentified falconiform 2 0 0 Long-eared Owl {Asio otus) 0 0 1 Eurasian Eagle Owl {Bubo bubo) 1 0 0 Total {N) 40 15 2 ®A — electrocutions on medium voltage (<60 kV) distribution lines in the Plain of Crau (IBA PAC 03) (Kabouche 1991, Bayle unpubl. data). B — electrocutions and collisions on medium volt- age distribution lines in the Vigueirat marshes (IBA PAC 08) (Hecker et al. 1992, Lucchesi unpubl. data). C — collisions on very high voltage (>150 kV) distribution lines in the saltworks of Fos-sur-Mer (IBA PAC 15) (Bayle and Iborra unpubl. data). companies to inform, sensitize and convince them that it is necessary to prevent raptor mortality on their networks. It is elusive to expect that any type of problem on powerlines will be solved without the cooperation of the power companies. Proposed methods to reduce avian mortality on powerlines must first be tested with mock poles and wires and slow motion film or video, either on captive birds in specially designed aviaries (studies carried out in France by the “Union Nationale des Centres de Sauvegarde de la Faune Sauvage”) or on trained birds in the field (Nelson and Nelson 1977), to see how the birds react to the devices. This experimental phase is often overlooked by power companies (mainly for financial reasons) but is, by no means, superfluous. For example, in France, 55 poles were equipped with a plastic, spi- ral prototype on a 5-km-long portion of a 20-kV powerline to stop massive electrocutions of kes- trels; during the year that followed, 62 of kestrels and one hobby were found electrocuted under the supposedly neutralized poles (Brochet 1993) . All powerline portions with high risks for raptors must be modified to avoid avian mortality. On lines where collisions occur this can be done by install- ing warning devices on the wires (such as colored plastic spirals) or by setting up frightening objects on the poles (such as oversized raptor silhouettes) in order to drive the birds away from the lines (Raevel and Tombal 1991). Different devices have been developed to reduce electrocution, either by assuring a better isolation between electric wires and pylons (for example by isolating the wire or the pole with a plastic sheath) or by preventing birds from perching on electric poles (Vereinigung Deutscher Elektrizitatswerke 1991). Pylons can also be modified, especially to protect large raptors, by adding a special perch above the wires. All lines must be checked after they have been equipped in order to test the efficiency of the de- vices. For example, taper-like plastic poles which were placed on dangerous pylons around the col- ony of reintroduced Griffon Vultures in the French Cevennes National Park were inefficient and did not prevent the electrocution of two young birds which managed to perch between the obstacles (Terrasse pers. comm.). Although some European power companies are very satisfied with these devices and argue that they reduce avian mortality by 90-95%, most of them can be considered as only expedients. As far as me- dium voltage powerlines are concerned, an under- ground network is the only totally efficient solution to raptor mortality. There are no technical prob- lems for the burial of medium tension lines and, at least in the small and densely populated Euro- pean countries, the financial costs are equivalent to those for the setting up of overhead lines. All voltage powerlines in the Netherlands are under- ground and other west European countries intend to bury all their medium voltage lines in the near future. At the beginning of the 1990s, 77% of the transmission lines in Belgium were already under- ground, 56% in (West) Germany and 44% in the U.K., but south European countries such as Italy, France and Spain are well behind with only 22%, 19% and 13%, respectively, of their medium volt- age lines buried (Vallet 1991, Anonymous 1993). These figures explain why the mortality of raptors on powerlines is so acute in the two latter coun- tries, although other factors such as powerline configuration and raptor densities may also gready influence the situation. The conservation com- munity must insist that power companies (and gov- ernments) undertake measures to enforce the burial of the whole network in order to suppress avian mortality on medium tension lines. In coun- tries such as France and Spain where so much still March 1999 Expanded Abstracts 47 needs to be done, it cannot be reasonably expect- ed that all lines will be buried soon. Priority actions on problem powerlines must be determined on a national level between conservation groups and power companies. In France, for example, the two main bird protecting societies, the “Ligue pour la Protection des Oiseaux” (LPO) and the “Fonds d’ Intervention pour les Rapaces” (FIR) have listed eight priority bird species, among which are Os- preys {Pandion haliaetus) , Red Kites, Bonelli’s Ea- gles, Golden Eagles, Griffon Vultures and Eurasian Eagle Owls, as well as White Storks ( Ciconia ciconia) and Common Cranes (Grus grus). Conservation measures should first be undertaken on lines that lie across natural landscapes with large populations of raptors or which shelter endangered species. Such sites are already listed among IBAs and some- times protected as Ramsar Sites or as natural re- serves with a bird conservation vocation. LPO and FIR have asked the national power company “Elec- tricite de France” (EDF) to cooperate in the estab- lishment of a national action plan on these bases. To this date, EDF refuses to recognize the need to inventory priority zones. EDF concedes today that preventing hird of prey mortality on powerlines cannot be considered anymore as a m^or techni- cal problem (Vallet 1991). Literature Cited Agrupacion Naturalista Esparvel. 1993. La electrocu- cion de rapaces en la provincia de Toledo. Quercus 94; 24-29. Anonymous. 1993. La France en retard pour I’enfouissement des lignes. L’Environnement-Magazine 1521:44. Bayle, P. 1992. Le Hibou grand-due Bubo bubo dans le Parc National du Mercantour et ses environs. P.N. Mercantour, Nice, France. Brocket, J. 1993. Experimentation des prototypes spirale (SAAE) et Piver (RAYCHEM) sur les lignes EDF MT 20.000 volts Compertrix — Haussimont (1991-92). LPO & EDF, Rochefort, France. Castano, J.P. and J. Guzman. 1989. Mas de 70 rapaces mueren electrocudas en dos tendidos electricas de Ciudad Real. Quercus ^'A\. Cheylan, G., a. Ravayrol, J.-M. Cugnasse, J.-M. Billet AND C. JOULOT. 1996. Dispersion des aigles de Bonelli Hieraaetus fasciatus bagues en France. Alauda 64:413-419. CouLOUMY, C. 1993. Causes de mortalite de I’Aigle royal en region Provence — ^Alpes — Cote d’Azur. Faune &' Nature (Bull. ARPON) 35:9-13. Deschamps, P. 1980. Point local sur P electrocution des rapaces (et autres oiseaux) sur les lignes a moyenne tension de la region grenobloise. La Niverolle 5:59— 66. Ferrer, M. and F. Hiraldo. 1990. Evaluation of manage- ment techniques for the Spanish Imperial Eagle. Wild- life Soc. Bull. 19:436-442. , M. de la Riva andJ. Castroviejo. 1991. Electro- cution of raptors on power lines in southwestern Spain./. Field Ornithol. 62:181-190. , G. Janss and M.L. Chacon. 1993. Mortalidad de aves en tendidos electricos: situacion en Espana. Quer- cus 94:20-23. Gensboel, B. 1984. Collins Guide to the birds of prey of Britain and Europe, North Africa and the Middle East. Collins, London, U.K. Haas, D. 1980. Gefahrdung unserer Grossvogel durch Stromschlag — eine Dokumentation. Oekol. Vogel 2 (Sonderheft) :7-57. Haller, H. 1978. Zur Populationsokologie des uhus Bubo bubo im Hochgebirge: Bestand, Bestandesentwicklung und Lebensraum in den Ratischen Alpen. Orn. Beob. 75:237-265. Hecker, N., a. Mante and J.-L. Lucchesi. 1992. Etude de la reaction des oiseaux aux differents systemes de visualisation de la ligne moyenne tension sur le do- maine du Vigueirat (commune d’Arles, Bouches-du- Rhone) . Station Biologique de la Tour du Valat, Arles, France. Heijnis, R. 1980. Vogeltod durch Drahtanflug bei Hoch- spannungsleitungen. Oekol. Vogels (Sonderheft.):! 1 1- 129. Hernandez, M. 1989. Mortalidad del buho real en Es- pana. Quercus 40:24—25. Hoerschelmann, H., a. Haack and D.F. Wohlgemuth. 1988. Verluste und Verhalten von Vogeln an einer 380-kVFreileitung. Oekol. Vogel 10:85-103. Kabouche, B. 1991, Une prospection des reseaux elec- triques de moyenne tension autour de St.-Martin-de- Crau (Bouches-du-Rhone) . CEEP, Aix-en-Provence, France. Mikkola, H. 1983. Owls of Europe. T. & A.D. Poyser, Cal- ton, U.K. Mugica, a. 1989. Aves electrocudas en la Comunidad de Madrid. Quercus 39:29. Negro, J.J. and M. Manez. 1989. Impacto de los tendidos sobre la avifauna. Quercus 39:25-29. Nelson, M. And P. Nelson. 1977. Power lines and birds of prey. Pages 228-242 in Chancellor and Meyburg [Eds.], 1st World Conference on Birds of Prey, Vien- na, 1975, Berlin, Germany. Newton, I. 1979. Population ecology of raptors. Poyser, Berkhamsted, U.K. Olsson, V. 1979. Studies on a population of Eagle Owls Bubo bubo (L.) in southeast Sweden, Viltrevy 11:1-99. Penteriani, V. and F. Pinchera. 1991. Densite, distribu- tion et causes du declin d’une population de Hiboux grands-ducs. Bubo bubo, dans les Abruzzes (centre de 48 Expanded Abstracts VoL. 33, No. 1 ritalie). Rapaces Nocturnes — ^Actes du 30e Colloque interregional: 1 89-1 93. Raevel, R and J.-C. Tombal. 1991. Impact des lignes haute-tension sur I’avifaune. Amenagement et Environ- nement 1:1-56, Real, J., S. Manosa, G. Cheylan, R Bayle, J.-M. Cugnas- SE, J.A. Sanchez, M.A. Sanchez, D. Carmona, J.E. Martinez, L. Rico, J. Godina, R. Del Amo and S. Eguia. 1996. A preliminary approach to the European Bonelli’s Eagle population decrease in Spain and France. Pages 523-528 in B.-U. Meyburg and R.D. Chancellor [Eds.], Eagle studies. World Working Group on Birds of Prey and Owls, Berlin, Germany. Rocamora, G. 1994. Les zones importantes pour la con- servation des oiseaux en France. LPO, Rochefort, France. Segara, D. and J.A. Martos. 1993. Trampa mortal en las lineas de alta tension. La Vanguardia 18/09/93:8-9. Seriot, J. AND G. Rocamora. 1992. Les rapaces et le re- seau electrique aerien. Analyse de la mortalite et so- lutions. LPO & EDF, Rochefort, France. Terrasse, M., C. Bagnolini,J. Bonnet, J.-L. Pinna and F. SarrAZIN. 1994. Reintroduction of the Griffon Vulture Gyps fulvus in the Massif Central, France. Pages 479-491 in B.-U. Meyburg and R.D. Chancel- lor [Eds.], Raptor conservation today. World Work- ing Group on Birds of Prey and Owls, Berlin, Ger- many. Vallet, G. 1991. Developpement des reseaux souterrains HT en rural. Guide Technique de la Distribution d’Electricite, document A. 15-1. EDF GDF Services, Paris, France. Vereinigung Deutscher Elektrizitatswerke. 1991. Vo- gelschutz an Starkstrom-Frei-leitungen mit Nennspan- nungen fiber 1 kV, 2. Auflage. VWEW-Verlag, Frank- furt-am-Main, Germany. WiCKL, K.-H. 1979. Der Uhu {Bubo bubo) in Bayern. Gar- mischer Vogelkundliche Berichte 6:1-47. / Raptor Res. 33(l):49-52 © 1999 The Raptor Research Foundation, Inc. RAPTOR USE AND ABUSE OF POWERLINES IN SOUTHERN AFRICA John A. Ledger Endangered Wildlife Trust, Private Bag x 11, Parkview, 2122 South Africa Jonathan C.A. Hobbs Environmental Policy and Strategy Division, Eskom, PO. Box 1091, Johannesburg, 2000 South Africa Powerlines pose problems to raptors when they nest, roost, collide with or are electrocuted by elec- tricity wires and their supporting structures. Rap- tors gain advantage from nesting and roosting on electricity towers, while eagles and vultures are killed by flying into wires or being electrocuted on towers. Collisions are not known to be a problem for raptors in southern Africa, but electrocution is a serious mortality factor for vultures and eagles. The problems inevitably arise from the design of the electricity structures, and all new powerlines in Africa should be designed to bird-friendly stan- dards. Various methods are available to retrospec- tively modify dangerous structures but they are both time-consuming and expensive. Raptors and Powerlines Although this paper concerns itself with south- ern Africa, it is noteworthy that only one paper has been published about raptor mortality on power- lines elsewhere in Africa. Nikolaus (1984) record- ed the electrocution of at least 55 Egyptian Vul- tures {Neophron percnopterus) and four Lappet-faced Vultures (Torgos tracheliotus) in Sudan in 1982 and 1983. There must be countless interactions be- tween raptors and powerlines in Africa, yet they remain undocumented. There is one report that includes details of raptors nesting on transmission towers in Namibia (Brown and Lawson 1989) but all Other published information on the subject is from South Africa, where one utility, Eskom, sup- plies 90% of the country’s electricity (as well par- tial supplies to neighboring states of Botswana, Le- sotho, Mozambique, Namibia, Swaziland and Zimbabwe). Eskom generates more than 50% of the electricity consumed on the African continent (Eskom 1991), and operates a vast national grid of 765, 400, 275, 132, 88 and 66-kV transmission lines, and a rural distribution system of 22 and 1 1 kV on woodpole construction, estimated to comprise some 60 000 km. Africa is home to a large variety of raptors, some of which, like large eagles and vultures (Mundy et al. 1992) are particularly sus- ceptible to electrocution on powerlines. Prior to 1977, there was no systematic recording of raptor and powerline interactions on Eskom’s network. Dean (1975) published the first records of Martial Eagles (Polemaetus bellicosus) nesting on transmission towers, while Markus (1972) had ear- lier recorded the mortality of Cape Griffons {Gyps coprotheres) by electrocution on 88-kV towers. As part of an ongoing research program on the Cape Griffon, the problem of electrocution was exam- ined (Ledger and Annegarn 1981) and in 1977, a mutually beneficial association between the Endan- gered Wildlife Trust and Eskom was entered into which has endured to the present. Eskom estab- lished a bird research committee, now known as Eskom’s Wildlife Impacts Advisory Committee (EWIAC). This group started collecting data on bird-powerline interactions in a systematic way and encouraged outside research workers to undertake projects of their own. Today, there is a large body of information avail- able about raptors and powerlines (Allan 1988, Boshoff 1993, Hobbs and Ledger 1986a, 1986b, Hobbs et al. 1990, Ledger 1983, 1984, Ledger and Hobbs 1985, Ledger et al. 1987). Eskom has pub- lished its own Bird Identification Guide (Ledger 1988) for maintenance personnel that summarizes the problems and solutions. EWIAC meets bian- nually but urgent matters are dealt with on an ad hoc basis by J.A.Ledger, who serves as a consultant to Eskom. EWIAC was originally a problem-solving committee, but with the devolution of environmen- tal responsibility to the various operational regions (or business units), the problems are being solved at this level and the biannual meetings provide an opportunity for information-sharing. 49 50 Expanded Abstracts VoL. 33, No. 1 Solving Problems of Raptors and Powerlines Prior to the establishment of Eskom’s bird re- search committee in 1977, it was normal practice for all nests to be removed from transmission tow- ers during annual maintenance, regardless of their contents. Apart from the costs of such unnecessary work to Eskom, this must have caused widespread raptor mortality. The opportunity for introducing some biological thinking into an engineering en- vironment arose through the meetings of the com- mittee. It was pointed out that problems of birds nesting on towers normally occur during the early phases of nest building, when long branches and sticks, or even pieces of wire may fall from the crossarm onto the conductor below, causing a flashover. Once nests are constructed and occu- pied, raptors will use them for years, and generally maintain them in good condition. The removal of nests from towers by Eskom maintenance personnel was subsequently prohib- ited, except in those cases where the nest was col- lapsing and posed a direct threat to the electricity supply. Since this new approach to nest conserva- tion has been adopted, a wide variety of raptors including Tawny Eagles {Aquila rapax), Black Ea- gles (Aquila verrauxii. Ledger et al. 1987), Martial Eagles, African Hawk Eagles (Hieraaetus fasciatus). White-backed Vultures ( Gyps africanus, Ledger and Hobbs 1985), Lanner Falcons {Falco biarmicus). Greater Kestrels {Falco rupicoloides) and Rock Kes- trels {Falco tinnunculus) are now breeding on trans- mission towers. The first five species construct their own nests, while the three Falco species use nests originally built by eagles or crows. If long sticks project below the nest, the solution is to trim them away during maintenance work, to prevent the oc- currence of flashovers in wet weather. Should a nest containing young start to collapse because of wind, the whole structure can be secured to a wooden platform with wire, and the raptors will continue to feed their chicks. This has been done successfully with a Black Eagle nest in the Karoo. Although nesting platforms have been used suc- cessfully in the U.S., we have found that raptors do not readily use them in southern Africa and seem to have very definite preferences for making their own decisions about which towers they will select. The value of electricity transmission towers as nesting sites for raptors is highlighted in a recent paper by Boshoff (1993). He monitored 7-18 pairs of Martial Eagles breeding in Eskom transmission towers in the Nama-Karoo over a period of 5-10 yr. This was done by making an annual series of flights in fixed-wing aircraft along 420 km of pow- erline. Mean linear density was 1 pair/ 19 km and mean minimum territory size was 284 km^. Lack of marked variation in annual breeding effort indi- cated that the population was stable. Breeding suc- cess was 0.70 (eggs to nestlings) and 0.62 (breed- ing attempts to nestlings) . Overall minimum reproduction rate was 0.52 young/pair/yr. Boshoff (1993) concluded that Martial Eagles obtain in- creased breeding success on electricity transmis- sion towers. He suggested that persecution of birds on towers may be, less than for birds nesting in low trees or the large boulders and low cliffs found in the Nama-Karoo. Safety from predators was also a factor, as towers provide a nesting substrate inac- cessible to mammalian predators, including man. Boshoff also recounted the case of a pair of Martial Eagles which nested in a highly vulnerable position in a tree on a low cliff. They built a new nest on an Eskom tower within one year of the construc- tion of the powerline. The only raptors that roost in any numbers on Eskom towers are vultures, and in certain parts quite large numbers of (up to 100) Cape Griffons, sometimes with a few White-backed Vultures, roost over a number of towers of a transmission line. A few problems arising from the pollution of insula- tors with excreta from the birds have been en- countered. The only solution has been to fit shields above the insulator strings, but the roost may move elsewhere along the line, depending on the availability of carrion. In a few cases, it proved necessary to wash the insulators from a helicopter which was a very expensive undertaking. It has also been found that V-string insulators are much more susceptible to pollution by vulture excreta than straight strings, and that a rubber dustbin lid makes a very good shield for the latter. Some birds will collide with overhead wires all the time. The impact of this depends on the fre- quency of occurrence and the effects of the mor- tality on the particular species of bird. There is no evidence of any raptor being seriously at risk from collision with overhead wires in southern Africa. Where raptors are consistently at risk, the conduc- tors can be marked using PLP Bird Flight Deflec- tors. These are plastic spirals which clip onto the wires and make them visible to the birds. Electrocution of Cape Griffons on 88-kV trans- mission towers in the western Transvaal was due to March 1999 Expanded Abstracts 51 the incompatibility of a large bird with a dangerous design, the so called ‘kite construction.’ Vultures were killed by landing on the crossarm of the tower and contacting a conductor with their extended wings. A 3-yr study identified the specific problem areas, and perches were fitted to several hundred towers. This largely solved the problem but, where it persisted due to high densities of roosting vul- tures, PVG spirals were fixed to the middle con- ductor around the insulator clamp to create a bar- rier to wing tips touching conductors at the moment of landing. The ‘kite construction’ has been outlawed for use in rural areas. A more insidious problem has been the electro- cution of raptors on 1 1 and 22-kV lines, of which an estimated 60 000 km cross rural terrain within South Africa, while Botswana, Lesotho, Namibia, Swaziland and Zimbabwe also have extensive net- works of similar design. The m^ority of these lines were constructed on wooden poles with a horizon- tal crossarm bearing the conductors on pin or post insulators above the crossarm. In many cases, an earth downlead for lightning protection runs up the pole and terminates in a spike between the middle and an outer insulator. The potential for phase to phase, or phase to earth electrocutions on such structures is clearly great particularly with the information available from the U.S. (Olendorff at al. 1981), yet very little information on raptor mortality has accumulated over the years that EWIAC has been active. A recent questionnaire survey conducted in the Colesberg district of the Eastern Cape Region (Ledger et al. 1992) elicited the following raptor electrocution figures from 55 respondents: 21 Mar- tial Eagles, 20 Black Eagles, 20 vultures (of which four were Cape Griffons); 15 ‘eagles,’ 6 ‘hawks,’ 6 ‘owls,’ and 2 Jackal Buzzards. An unexpected finding from the survey was the extent to which raptors are electrocuted on ter- minal structures in rural areas. On many farms, there may be a number of such structures where the overhead line terminates at a transformer to supply a water pump or other equipment. The ter- minal structure is usually a twin-pole design with a horizontal crossarm hearing three strain insulators for the incoming conductors. Jumper leads from these three conductors go downward to connect to the transformer, while another three jumper leads go above the crossarm to connect to the lightning arrestors. The crossarm is bonded and earthed. and any bird which perches on the crossarm and touches one of the jumpers is electrocuted. The solution to these hazards is relatively simple, but time-consuming and labor-intensive. Interme- diate structures can be made safe by cutting a 500- mm gap in the earth downlead (or removing the earth spike completely and terminating the down- lead just below the crossarm braces) , in conjunc- tion with insulation of the middle phase conduc- tor. This can be achieved by fitting the locally developed RP 3 Raptor Protector (Ledger 1992), or by fitting a length of split XLPE (cross-linked polyethylene) tubing to the middle phase conduc- tor. To make the terminal structures safe for raptors, split XLPE insulation must be fitted to all the jumper leads above the crossarm, and it is also good practice to do the same to the jumpers run- ning to the transformer. On new structures, insu- lated conductors should be used for all jumpers. Lightning arrestors are now fitted on the trans- former rather than the crossarm. Eskom management agreed in 1991 to direct that only bird-friendly designs should be used in rural areas in the future. The design of choice is the single pole with staggered insulators, as de- scribed by Hobbs et al. (1990) , although an equally good design is one where the outer conductors hang below the crossarm on suspension insulators. Of great concern is the ongoing construction of bird-unfriendly powerlines throughout Africa. Literature Cited Allan, D. 1988. Raptors nesting on transmission pylons African Wildl. 42:325-327. Boshoff, A.F. 1993. Density, breeding performance and stability of Martial Eagles Polemaetus bellicosushreeding on electricity pylons in the Nama-Karoo, South Africa Proc. VIII Pan-Afr. Orn. Congr. 95-104. Brown, C.J. and J. Lawson. 1989. Birds and electricity transmission lines in south west Africa/Namibia. Ma- doqua 16:59—67. Dean, W.R.J. 1975. Martial Eagles nesting on high tension pylons. Ostrich 4&:\\%-\\7 . Eskom. 1991. Eskom in perspective, 1991 Annual Report. Eskom, Johannesburg, South Africa. Hobbs, J.C.A. and J.A. Ledger. 1986a. The environmen- tal impact of linear developments; powerlines and avi- fauna. Third International Conference on Environ- mental Quality and Ecosystem Stability. Eilat, Israel. AND . 1986b. Power lines, birdlife and the golden mean. Fauna and Flora 44:23-27. , and T. Auditore. 1990. The impacts of powerlines on wildlife. Electricity SA, March/April 52 Expanded Abstracts VoL. 33, No. 1 1990, Crown Publications, Johannesburg, South Afri- ca. Ledger, J.A. 1983. Guidelines for dealing with bird prob- lems on transmission lines and towers. Eskom Test and Research Division Technical Note TRR/N83/ 005, Johannesburg, South Africa. . 1984. Engineering solutions to the problem of vulture electrocutions on electricity towers. The Certif- icated Engineer 57:92-95. . 1988. Eskom bird identification guide. Eskom, Johannesburg, South Africa. . 1992. Protecting eagles and other large birds from electrocution on rural powerlines. South African Eagle Insurance Company Limited, Johannesburg, South Africa. AND HJ. Annegarn. 1981. Electrocution hazards to the Cape Vulture Oyps coprotheres in South Africa. Biol. Cons. 20:15-24. andJ. Hobbs. 1985. First record of African White- backed Vultures nesting on man-made structures. Bok- makierie 37:99—109. , AND T.V. Smith. 1992. Avian interactions with utility structures: southern African experiences. Proc. International Workshop on Avian Interactions with Utility Structures, Miami, FL U.S.A. , AND D. Van Rensburg. 1987. First record of Black Eagles nesting on an electricity transmission tower. African Wildl. 41:60-66. Markus, M.B. 1972. Mortality of vultures caused by elec- trocution. Nature 238:228. Mundy, R, D. Butchart, J. Ledger and S. Piper. 1992. The vultures of Africa. Acorn Books/Russel Friedman Books, Johannesburg, South Africa. Nikolaus, G. 1984. Large numbers of birds killed by elec- tric powerline. Scopus 8:42. Olendorff, R.R., A.D. Miller and R.N. Lehman. 1981. Suggested practices for raptor protection on power- lines — the state-of-the-art in 1981. RRF Report 4, Washington, DC U.S.A. J. Raptor Res. 33(l):53-58 © 1999 The Raptor Research Foundation, Inc. USING A GIS TO INTEGRATE SEASONAL RAPTOR DISTRIBUTIONS INTO A BIRD AVOIDANCE MODEL FOR AIRCRAFT Michael M. Thompson HQAFCESA/DMPS, 139 Barnes Drive, Tyndall Airforce Base, FL 32403 U.S.A. Military aircraft are particularly vulnerable to bird strikes as they routinely operate at low altitudes and high speeds. The U.S. Air Force (USAF) reports 3500 birdstrikes each year. These incidents have caused the loss of numerous jet mrcraft, many with resultant fatalities and cost the USAF an average of over 65 million dollars each year (Merritt and Dogan 1992). The variety of birds struck by low-flying aircraft num- bers in the hundreds, but raptors pose the most se- rious threat. Raptors are responsible for 46% of the damaging bird strikes (>$10000) and Red-tailed Hawks {Buteo jamaicensis, 32%), Turkey Vultures (Ca- thartes aura, 31%), Black Vultures (Coragyps atratus, 13%), Golden Eagles {Aquila chrysaetos, 2%) and Broad-winged Hawks {Buteo platypterus, 2%) account for 80% of these. The disproportionate amount of raptor damage results because of the relatively large size of raptors and the fact that these birds make foraging and migratory flights at the same altitudes as military flight operations. To reduce hazardous and costly bird strikes to aircraft, the USAF Bird Aircraft Strike Hazard (BASH) Team is developing a Bird Avoidance Model (BAM), which is designed to calculate the relative risk for an aircraft collision with a bird by integrating biological and geographical data into a Geographical Information System (GIS). Modeling for the USAF uses the Geographic Resource Anal- ysis Support System (GRASS) GIS. The BAM calculates the risk for striking a bird based on selected bird density and aircraft position criteria. The risk algorithm includes differing bird types by considering population densities, species weights and bird behavioral differences. The tem- poral aspects of hazard, including time of year (sea- sonal variation) and time of day (diurnal variation) with altitude distribution for each temporal compo- nent, are incorporated in the risk assessment. The GRASS output, provided to military flight and mis- sion planners, contains a graphical depiction of bird hazards, a pictorial representation of the most serious concerns, and a text file with recommendations for aircraft operations in the vicinity of the hazard. Geographically referenced population and mi- gration dynamics data for waterfowl (ducks, geese and swans), raptors, cranes, pelicans, gulls and blackbirds were collected and entered into dBase III+ files. Most data files were developed from qualitative information, though databases such as the North American Breeding Bird Survey (BBS), Audubon Christmas Bird Count (CBC), Hawk Mi- gration Association of North America (HMANA) and bird-banding recoveries were used to verify raptor distribution and abundance in the BAM. BBS data were used to estimate summer popula- tions for most raptor species. The BBS is a standard- ized survey conducted each year at 2791 point sites throughout the U.S. and Canada during the spring and early summer to index North American bird populations (Bystrak 1981). CBC data were used to distribute the winter populations for most raptor spe- cies. The CBC is a standardized survey of birds count- ed within a 15-mile diameter circle at 1500 locations on one day during 15 December-5 January (Bock and Root 1981). HMANA count data were used to determine tbe distribution of migrant raptors during different seasons and at various sites across the U.S. and Canada. Each species’ population distribution was determined using HMANA data collected within respective regions selecting sites with good seasonal and hourly data for California and the Western, Cen- tral, Eastern and Atlantic Regions within 42—46°, 38- 42° and <38° north latitude bands. Sightings per hour were converted to a percentage of each migrant population distributed within 2-wk periods. Bird-banding recovery data maintained by the U.S. Fish and Wildlife Service provided additional information on fall migration pathways and win- tering and migrating distributions. April— October banding and November-February recovery data were analyzed since birds should have already been in breeding areas by April, and birds banded at northern sites in October were just beginning tbeir migration. There were limitations on using these data for some raptor species for various reasons: (1) a ban on vulture banding because of injuries 53 54 Expanded Abstracts VoL. 33, No. 1 resulting from excrement accumulating under the bands, (2) Broad-winged Hawks banded in relative- ly small numbers due to migratory habits and (3) insufficient direct recovery of banded Golden Ea- gles to construct migration pathways. The BBS and CBC records are the only continent- wide bird population counts available, but cannot be directly compared since they are not collected with similar techniques and are somewhat qualita- tive. Despite these drawbacks, the surveys can be used to determine the relative abundance and dis- tributions for common species in summer and win- ter. Actual population numbers in the BAM are not as important as the relative abundance among the migratory, breeding and wintering distributions. The breeding bird population size and distribu- tion for a raptor species was determined by distrib- uting BBS data within 83 physiographic regions (Bystrak 1981), which were based on common soils, land use, natural vegetation, landforms and surface geology (U.S. Department of Agriculture 1981). The BBS summer population was calculated using the equation: [#R/ (12.25 X #B)] X A, where #R is the sum of the number of birds seen in each region, 12.25 is the area of a single BBS route in square miles, #B is the number of BBSs in the physiograph- ic region and A is the area of the region in mi^. Once the breeding population was calculated, it was used as a population basis and other populations were expressed relative to it as follows: Summer Population = Breeding (BBS) + Nonbreeding (assumed 15%) Late Summer Population = Summer (Canada + U.S.) + Offspring Resident Population = Late summer X %Nonmigrant (summer to winter band recoveries <50 mi) Fall Migrant Population = Late summer (Canada + U.S.) — Resident Winter Population = Fall migrant + Resident Spring Migrant Population = Fall migrant — 40% loss Nonbreeding and offspring percentages of breeding populations for raptor species were ob- tained from published or survey data, or estimates based on similar species. Fall migrants and non- migrants were apportioned to north latitude bands (42-46°, 38-42° and <38°). Migrant pathway pop- ulations reflected only migrant numbers within that latitude band and migrant density was de- creased by the migrant wintering stopover number as the migration pathway extended southward. The migrant wintering stopover number was calculated from the percent nonmigrant in each latitude band. It was assumed that the winter residents which did not survive were replaced by migrant wintering birds, thus maintaining a stable resident population in the spring. The spring migrant pop- ulations were reduced by 40% from the fall mi- grant numbers. Raptor altitude distributions for migrant and res- ident raptors came from radar data but were not available for all regions. Reports by Kerlinger (1985), Kerlinger and Gauthreaux (1984, 1985a, 1985b), Kerlinger et al. (1985), Cooper et al. (1988, 1989, 1990a, 1990b), Day and Byrne (1989), Hoff- man (pers. comm.), Mindell (1984), Palmer (1988), Coleman and Fraser (1989) and Kelly (1992) were used to help develop the distributions for the BAM. A few examples of behavior used in the model are: (1) early spring arrivals reach northern states while snow is still on the ground, weather is cold and thermals are scarce; the birds should generally move at <200 ft above ground level (AGL) under these conditions; (2) resident Red-tailed Hawks have a preference for perch-site foraging rather than by soaring but can be expect- ed to soar in areas with few perches and much lift from physical features; (3) Black Vultures spend more time flying higher than Turkey Vultures, watching as Turkey Vultures hunt hy scent and lead the Black Vultures to carrion; (4) Resident Golden Eagles tend to feed early and late in the day, even though there is little thermal lift, when food sourc- es are most active in the subdued light. Much more quantitative information is needed on altitude dis- tributions, which are an important component in the BAM. Example Data Although Red-tailed Hawks, Turkey Vultures, Black Vultures, Golden Eagles and Broad-winged Hawks were all included in the BAM, results and summaries from data analyses for all species are March 1999 Expanded Abstracts 55 Table 1 . Comparison of Red-tailed Hawk migration dis- tances by region of the U.S. Region Number Band Recoveries Mean Distance ( mi) California 41 75 Western 44 229 Central 85 475 Eastern 256 399 Atlantic 172 243 too lengthy to include in this paper. Since the an- alyses are similar, only the red-tail data are de- scribed here, with brief mention of the other spe- cies. Red-tailed Hawk Populations (U.S.). Using BBS data I estimated the U.S. population of red-tails to be 800 000 hawks. In summer, the population grew to an estimated 920 000 hawks and in late summer it increased to an estimated 1 520 000 hawks (>42° = 456 000, 38-42° = 304 000 and <38° = 760 000 hawks) . The resident population of red-tails was es- timated to be 637 000 (>42° = 87000, 38-42° = 109 000 and <38° 441 000 hawks). The population of fall migrants was estimated to be 2 328 000 hawks (>42° = 936 000, 38^2° = 739 000 and <38° = 653 000 hawks) . Winter populations were estimated to be 1568 000 hawks (>42° = 220 000, 38-42° = 447000 and <38° = 901000 hawks). The spring migrant population was 1 430 000 hawks (>42° = 562 000, 38-42° = 476 000 and <38° = 392000 hawks) . Chronological Distribution of Migrants. HMANA data indicated that the m^or migratory movement of red-tails was between 10 October-13 November, Since there are regional and latitudinal differences (e.g., peak passage of red-tails in the western re- gion was 2-3 wk earlier than in other regions) , the migrant chronology was estimated as the percent- age of migratory population movements per 2-wk period, through three latitude bands and 14 re- gions. Migration Pathways. Analysis of direct (same year) banding recovery data provided the best pic- ture of Red-tailed Hawk fall movements. Migration distances were compared for Pacific, Western, Cen- tral, Eastern and Atlantic Regions (Table 1), with red-tail migration starting in northern (>42°), middle (38-42°) and southern (<38°) latitudes (Table 2). Movements of <50 mi were separated Table 2. Comparison of migration distances of Red- tailed Hawks in the U.S. by latitudinal bands based on band recoveries. Latitude Number Mean Distance Band Recoveries (mi ± SD) 42-46°N 402 420 ± 356 38-42°N 161 211 ± 248 <38°N 72 84 ± 119 by region and latitude band (Table 3) to indicate nonmigrator y birds. These broad analyses to determine the percent- age of the Red-tailed Hawks that are migratory confirmed findings from investigations with small- er samples. The most northern Red-tailed Hawks (>42°) are migratory whereas populations in the middle latitudes (38-42°) are only partly migratory and southern populations (<38°) are permanent residents (Brinker and Erdman 1985). More de- tailed data were available within some latitude bands. For example, recoveries of red-tails banded in California indicated that these birds are partial or nonmigratory, and birds banded in the Pacific Northwest are nonmigratory. In contrast, red-tails banded inland in the Northwest, away from the moderating Pacific influence, migrated long dis- tances with fall frontal winds and were sometimes recovered in California. Better data were needed to distribute count data throughout migration pathways defined by band recoveries. Leading lines may have accounted for only a small proportion of the migratory pathways of raptor populations in the U.S. since there are few long ridgelines and coastlines that are appro- priately oriented for migration. Some experts (Ker- linger et al. 1985) think too much emphasis has been placed on concentration zones associated with ridges, since mountain ranges may bnly have a local influence within 10 km. Red-tails may move Table 3. Comparison of numbers of migratory and non- migratory Red-tailed Hawks in the U.S. by latitudinal band. 42-46°N 38-42“N <38°N Migrant 327 103 30 Nonmigrant 76 63 42 Total observations 402 161 72 Percent nonmigrant 19 36 58 56 Expanded Abstracts VoL. 33, No. 1 along ridgelines when stable updrafts are generat- ed but generally have a low affinity for following leading lines. Radiotelemetry studies have revealed that Red-tailed Hawk migration occurs on a very broad front (>70% of the time hawks migrated away from ridges) . Some experts think that strong fall winds in the east tend to concentrate raptors toward the coast (Kellogg pers. comm.). Winds to- gether with the Appalachian Mountain chain may account for this concentration as indicated by banding data. Banding recovery and HMANA data indicated that Red-tailed Hawks migrate mosdy on a broad- front, but that barriers to migration, especially the Great Lakes and the Atlantic Ocean, tend to con- centrate red-tails and other raptors. Concentration zones in the BAM were based on HMANA count data and were expressed as two, three, and four times the normal regional and latitudinal distri- butions. Migratory movements were assumed broad-frontal throughout the latitudinal regions and on dispersal from concentration zones. Red-tailed Hawk altitude distributions for the 38-42° latitude band were summarized for resi- dents and five migrants. Altitude distributions were developed for ideal migrating conditions. For ex- ample, on days when good lift is available for soar- ing, 73% of red-tails (and other Buteos) should oc- cur between 1001-2000 ft. In cloudy conditions when there are not sufficient thermals, fewer Bu- teos may migrate, which would present a conserva- tive condition in the BAM. Nevertheless, such mi- gration as does occur could be mainly at 0-1000 ft, which increases the risk. The solution would be thermal prediction, but this would require BAM users to input weather data and is probably 5 yr away. Other Species Broad-winged Hawks are included in the model because large, predictable flocks concentrate along geographical leading lines. These birds tend to flock while migrating even away from recognized concentration zones, and are therefore potentially hazardous to aircraft. However, HMANA data in- dicate that the major broad-wing movements are within 2-wk periods (approximately 23 April— 7 May and 12-26 September) and do not present as se- rious a year-round hazard to aircraft as red-tails and vultures. Migratory broad-wing concentrations (from HMANA counts) result when one half or more of the population funnels into four relatively narrow corridors around or between the Great Lakes. In the southern U.S. nearly the whole broad-wing migration population goes around the Gulf of Mexico overland. Broad-wing migration can be summarized as follows: (1) it conforms to four travel lanes controlled by the Great Lakes cor- ridors; (2) in the eastern U.S., there is a wide lane that uses chiefly the updrafts of the Appalachian ridges; (3) in the central U.S., there is a wide path- way between the Mississippi River and the edge of the High Plains; and (4) in the center of the U.S., all broad-wings converge on south Texas in fall and diverge in spring northward. Turkey Vultures, like Red-tailed Hawks, are wide- ly distributed with large populations (late summer = 3 717 000 vultures). Their summer distribution encompasses virtually the entire continental U.S., while the winter range is generally restricted to the southern and coastal regions. The wide distribu- tion of this species together with its soaring behav- ior make it and red-tails the raptors most common- ly encountered by USAF aircraft. Unfortunately, banding data are essentially nonexistent and HMANA observers often discount vultures because they are uncertain if the birds are migratory or residents. Information on distribution and migra- tion of this species, of such importance to the BAM, is therefore essentially qualitative. However, it seems that Turkey Vultures may move on a broad front to an even greater extent than red-tails, since they are less dependent on ridge lift and wind con- ditions (Kellogg pers. comm.), and are remarkably adaptable to local conditions. They are generally lowland migrants and travel on thermals up to sev- eral thousand feet. In the east, migration is essen- tially a shift within the Canadian-U.S. breeding range, although some eastern birds may reach Lat- in America via the Florida Keys. In western North America, Turkey Vultures presumably migrate to Mexico, Central America and South America. There are now plans to use satellite spectral im- agery to correlate physiographic, geographic and climatic correlates to model the breeding and win- tering distributions of Turkey Vultures in the con- tinental U.S. (DeFusco 1993). This approach may be very valuable for BAM estimates in the future. Black Vulture population distribution is some- what limited and is essentially nonmigratory in the U.S. Data indicate that populations shift (migrate) relatively short distances and are more abundant southerly and toward coasts. Since migration peri- ods are relatively short and migration paths are dif- March 1999 Expanded Abstracts 57 ficult to define, I did not incorporate migration pathways into the BAM. There is insufficient banding data for Golden Eagles to construct migration pathways but season- al populations probably concentrate in states with ideal habitat. Data also suggest that migrants in the western U.S. move southeasterly with fall frontal winds and, in the east, follow the Appalachians tending to remain within preferred habitat. Migra- tory pathways in the BAM were based on the oc- currence in physiographic regions of habitat pre- ferred in the BBS distribution. Weather Wind direction, wind velocity, cloud cover, air temperature, barometric pressure and visibility all seem important during both spring and fall migra- tions (Heintzelman 1986). Considerable qualitative information has been published on weather effect- ing migration. Low barometric pressures north of a site triggers fall migrations and the passage of cold fronts aids migrations by producing favorable winds (Haugh 1972, Richardson 1978, Millsap and Zook 1983). Strong migrations usually continue 1-3 d following frontal passage (Heintzelman 1986). Fall migrations are dependent on local weather conditions but the general weather con- ditions are considered more important (Hoffman 1981, 1982). Spring migrations are much less stud- ied but Haugh (1972) suggested that warm front coupled with low pressure to the north and west triggered large migratory movements. However, it is not practical to include weather in the BAM until its effects on migration are more thoroughly de- fined. The Future Distributing BBS and CBC counts throughout physiographic regions was a convenient way to model population densities in the GIS. However, bird distributions may be refined in the BAM if vegetation, water, ridges and land use correlate with winter, summer and migration densities. For example, a low-level route with a typical 8-mi width may have agricultural crops, water and terrain pro- viding lift for raptors within or near the route which could concentrate migrants or attract win- tering stopover birds. The BAM provides the his- torical migrant pathways and seasonal population distributions, while satellite imagery will add a pre- dictive habitat component. The GRASS GIS BAM for the continental U.S. will be operational in October 1993. A model is underway for Alaska and a global one is planned. Data from Europe indicate that over 35% of USAF birdstrikes occur during low-level exercises, but the BASH Team has no way to assess potential bird haz- ards in Europe. Moreover, deployments in the Mid- dle East and Africa have emphasized the need to identify hazardous areas and times for the massive spring and fall migrations. We have begun a search for bird migration and concentration information for Europe, Africa and the Middle East to include raptor, waterfowl, pelican, stork and gull ringing, wintering, breeding, altitudinal and chronological distributions. Literature Cited Bock, C.E. and T.R. Root. 1981. The Christmas Bird Count and avian ecology. Stud. Avian Biol. 6:17—23. Brinker, D.F. and T.C. Erdman. 1985. Characteristics of autumn Red-tailed Hawk migration through Wiscon- sin, Proc. Hawk Migration Conf. 4. Bystrak, D, 1981. The North American breeding bird survey. Stud. Avian Biol. 6:34-41. Coleman, J.S. and J.D. Fraser. 1989. Habitat use and home ranges of Black and Turkey Vultures. J. Wildl Manag. 53:782-792. Cooper, B.A., R.J. Ritchie, B.A. Anderson and C.L. Cra- NOR. 1988. OTH-B avian survey field program. Metcalf and Eddy/Holmes and Narver, Wakefield, MA U.S A , R.J. Ritchie, B.A. Anderson and C.L. Cranor 1989. OTH-B avian survey field program. Metcalf and Eddy/Holmes and Narver, Wakefield, MA U.S.A. , R.J. Ritchie, B.A. Anderson, L.C. Byrne and C L Cranor. 1990a. OTH-B Alaska avian survey field pro- gram. Metcalf and Eddy/Holmes and Narver, Wake- field, MA U.S.A. , R.J. Ritchie, B.A. Anderson, L.C. Byrne and C L Cranor. 1990b. OTH-B avian survey field program. Metcalf and Eddy/Holmes and Narver, Wakefield, MA U.S.A. Day, R.H. and L.C. Byrne. 1989. Avian research program for the over-the-horizon backscatter central radar sys- tem, spring 1989: radar studies of bird migration Metcalf and Eddy/Holmes and Narver, Wakefield, MA U.S.A. DeFusco, R.R 1993. Environmental factors influencing Turkey Vulture distribution and abundance: a geo- graphic information system application study. Ph D. dissertation, Univ. Colorado, Boulder, CO U.S.A. Haugh, R.J. 1972. A study of hawk migration in eastern North America. Search 2:1-60. Heintzelman, D.S. 1986. The migration of hawks. Indi- ana Univ. Press, Bloomington, IN U.S.A. Hoffman, S. 1981. Western hawkwatching. HMANA News- letter 6:1-4. 58 Expanded Abstracts VoL. 33, No. 1 . 1982. Western hawkwatching. HMANA Newsletter 7:10-12. Kelly, T.A. 1992. The effects of thermal height on colli- sions of military aircraft with two species of raptor: Turkey Vultures {Cathartes aura) and Red-tailed Hawks {Buteo jamaicensis) . Durrell Institute of Conser- vation and Ecology, Canterbury, UK. Kerlinger, P. 1985. Daily rhythm of hawk migration, noonday lulls, and counting bias: a review. Proc. Hawk Migration Conf. 4. AND S.A. Gauthreaux, Jr. 1984. Flight behavior of Sharp-shinned Hawks during migration. I: over land. Anim. Behav. 32:1021-1028. AND . 1985a. Seasonal timing, geographic distribution, and flight behavior of Broad-winged Hawks during spring migration in south Texas: a ra- dar and visual study. Auk 102:735-743. AND . 1985b. Flight behavior of raptors dur- ing spring migration in south Texas studied with ra- dar and visual observations, f. Field Ornithol. 56:394— 402. , V.P. Bingman and K.P. Able. 1985. Comparative flight behavior of migrating hawks studied with track- ing radar during autumn in central New York. Can. J. Zool. 63:755-761. Merritt, R.L. and R.L. Dogan. 1992. Bird strikes to U.S. Air Force aircraft 1987-1991. Proc. Bird Strike Committee Europe 21:393-401. Millsap, B.A. AND J.R. Zook. 1983. Effects of weather on Accipiter migration in southern Nevada. Raptor Res. 17:43-56. Mindell, D.P. 1984. Raptor migration characteristics and hazard to aircraft. Institute for Raptor Studies, Tech. Rep. F33615-80-D-400 1/0042. Palmer, R.S. [Ed.]. 1988. Handbook of North American Birds. Vols. 4 and 5. Yale Univ. Press, New Haven, CT U.S.A. Richardson, W.J. 1978. Timing and amount of bird mi- gration in relation to weather: a review. Oikos 30:224— 272. U.S. Department of Agriculture, Soil Conservation Service. 1981. Land resource regions and major land resource areas of the U.S. Agriculture Handbook 296, Washington, DC U.S.A. J. Raptor Res. 33(1) :59-62 © 1999 The Raptor Research Foundation, Inc. SEASONAL VARIATION IN BIRDSTRIKE RATE FOR TWO NORTH AMERICAN RAPTORS: TURKEY VULTURE {CATHARTES AURA) AND RED-TAILED HAWK (BUTEO JAMAICENSIS) T. Adam Kelly 507 Hwy. 2297, Panama City, FL 32404 U.S.A. Herein I present an analysis of Bird Avoidance Model (BAM) methodology using records from birdstrikes of U.S. Air Force (USAF) aircraft with two North American raptor species: Turkey Vul- tures ( Cathartes aura) and Red-tailed Hawks (Buteo jamaicensis) . The relationship between six seasonal behavioral activities and the rate of collisions was used to determine whether, as BAM methodology assumes, migration is the behavior that causes the highest risk of collisions. I found that vultures are more likely to be in collisions with aircraft in the summer season, when the young of the year have left the nest, but before autumn migration begins. Conversely, Red-tailed Hawks are more likely to be in collisions with aircraft when adults have eggs in the nest. The lowest risk of a collision between an aircraft and either species is during the winter months. Temporal Variation in Birdstrike Rate Turkey Vultures (31%) and Red-tailed Hawks (32%) account for the majority of damaging raptor strikes to USAF aircraft. In 1985, the USAF Bird Aircraft Strike Hazard (BASH) team developed a raptor avoidance model to compliment the water- fowl model developed in 1982 (Merritt 1990). The raptor model was constructed using data supplied by the Hawk Migration Association of North Amer- ica (HMANA). The 1985 USAF Raptor Avoidance Model (BAM) recognizes only two activities, migra- tion and foraging flights, and it makes two key as- sumptions about the conflict between birds and aircraft: (1) that the standing populations of rap- tors in winter and summer present a constant risk of birdstrikes; (2) that migration increases the number and risk of birdstrikes. The formula for the BAM includes a constant to decrease the num- ber of raptors potentially encountered during win- tering and breeding seasons, in keeping with the significantly greater risk posed to aircraft by mi- grants compared to sedentary breeders or winter- ers (Mindell 1985). To test these assumptions, I constructed annual activity tables for both Turkey Vultures and Red- tailed Hawks by subdividing the U.S. into the three areas of longitude used in the BAM: East (55-87°), Central (87-104°) and West (104-130°). Within each of these six tables, data were grouped on the y-axis at intervals of 2° latitude to show clinal vari- ation in seasonal activities. Six categories of seasonal activities were de- scribed by the activity tables. They included win- tering, spring migration, eggs in nest, young in nest and summer and autumn migration behavior categories. The peak autumn and spring migration periods were obtained from count data for each species from HMANA data. Time periods for eggs in nest and young in nest were obtained directly from North American Nest Record Scheme data provided by the Cornell Laboratory of Ornithology for Red-tailed Hawks and from Jackson (1983) for Turkey Vultures. A regression line was passed through the mean dates for eggs in the nest at each 2° line of latitude. Lines with similar slopes were used to indicate start and finish dates for eggs in nest and young in nest periods. The time be- tween the end of autumn migration and the start of egg laying or spring migration was designated as the wintering period. Likewise, the period be- tween the end of young in nest and the start of autumn migration was determined to be the sum- mer period. The spring migration and eggs in the nest seasons overlapped wholly or partly at some latitudes. The overflight of southern breeders by migrants heading north has been recognized for Red-tailed Hawks (Palmer 1988). Using the BASH database, birdstrikes at known geographic locations were plotted as a circle onto the appropriate activity table. All strikes away from airfields and those near airfields but above 70 m were also included. The raptor BAM can be used to calculate the risk of a strike when approaching or departing an airfield, as well as on low-level routes, so data fitting this latter profile were also 59 60 Expanded Abstracts VoL. 33, No. 1 Table 1 . Seasonal variation in Turkey Vulture strikes in all regions of the U.S. Season Observed Number OF Strikes Expected Number of Strikes % Diff. Winter 59 106 -44% Spring migration 26 32 -19% Eggs in nest 27 31 -10% Young in nest 96 78 +23% Summer 54 29 +86% Autumn migration 44 34 +29% = 50.9017, P< .001. included. The data covered the period from 1975- 92. Based on my analysis, I concluded that the rap- tor BAM had a minimal effect on the strike rate for these two species since 1985. The temporal and spatial distribution of strikes from 1985-92 was consistent with that of 1975-85. The effectiveness of the raptor BAM is severely diminished by the dominance of Broad-winged Hawks (Buteo platypte- rus) in HMANA data. The Broad-winged Hawk is rarely struck by aircraft. Conversely, the Red-tailed Hawk and Turkey Vulture, which are frequently struck, are underrepresented in HMANA data. Counts were made of the number of strikes dur- ing each season and then compared with the ex- pected number of strikes during that period with Chi-square Goodness-of-Fit Test. To avoid totals in any season less than five, which would invalidate the test, counts from all three regions were summed before analysis (Tables 1, 2, Figs. 1, 2). The data indicated that the collision risk for air- . craft varies according to season for Turkey Vultures Table 2. Seasonal variation in Red-tailed Hawk strikes in all regions of the U.S. Season Observed Number OF Strikes Expected Number OF Strikes % Diff. Winter 36 58 -37% Spring migration 27 19 +42% Eggs in nest 41 28 +46% Young in nest 42 43 -2% Summer 38 35 +9% Autumn migration 28 34 -18% X^ = 19.0882, P< .01. (X^ = 50.9017, P < 0.001) and for Red-tailed Hawks (x^ = 19.0882, P < 0.01). The variation in strike rate in each season did not support the as- sumption that migratory activity was responsible for increasing the number of birds aloft and hence, the hazard posed to aircraft. During the au- tumn migration. Red-tailed Hawks had a strike rate below average, although Turkey Vultures showed a 29% {N = 10) increase in their strike rate. During spring migration, the strike rate for Turkey Vul- tures fell 19% {N = —6) but the strike rate for Red- tailed Hawks rose 42% {N = 8). Therefore, the BAM did not reflect accurately the strike rate for either species during one of their two migratory seasons. Both Turkey Vultures and Red-tailed Hawks showed a marked decline in the number of bird- strikes during the wintering period (—44%, N = —47 and —37%, N = —22, respectively). This was due to the relationship between thermal activity and strike rate for these two species. Both forage Figure 1 . Percent seasonal variation in mean strike rate of Turkey Vultures. March 1999 Expanded Abstracts 61 60 40 20 0 -20 ^0 -60 Winter Spring Egg Young Summer Autumn Migration Migration Figure 2. Percent seasonal variation in mean strike rate of Red-tailed Hawks. by soaring on thermals, without which they are un- likely to reach the height required to bring them into conflict with aircraft. The shorter day for rap- tors to forage in winter, higher natural mortality, increase in aircraft night flying, flights lost due to poor weather and the holiday period could all be contributing factors in reducing the strike rate dur- ing this period. During winter, migration lowers the density of both species in many northern areas of North America and there is a low likelihood of thermal conditions capable of bringing aircraft and soaring birds into conflict. This means that only a small number of flight routes are unsuitable. In the summer period, there was a marked dif- ference in strike rate between Turkey Vultures (86% above the mean, N = 25) and Red-tailed Hawks (9% above the mean, N = S). This was the period with the highest risk of Turkey Vulture strikes. The breakup of nesting territories of Red- tailed Hawks and the decline in soaring for terri- torial defense would reduce the amount of time spent on thermals. Furthermore, Red-tailed Hawks, which take live prey rather than carrion, are likely to spend progressively less time foraging as prey become more abundant and the juvenile dependency period ends. Turkey Vultures of any age need to gain altitude and spend time on ther- mals to locate their carrion food by visual and ol- factory means. Mortality of the species that form their carrion diet is also relatively low in the period before winter arrives. The time spent foraging each day would, therefore, be high during this period. The strike rate with Turkey Vultures possibly matches the increase in population density and for- aging time. During the period when eggs are in the nest, Turkey Vultures showed a below average strike rate ( — 10%, N = —3). At the same time. Red-tailed Hawks reached their peak strike rate (46% above the mean, N — 13). Red-tailed Hawks soar to ad- vertise their presence in the territory. During the incubation period, males must secure mates, for- age and maintain territories that enclose adequate food supplies for breeding. The high strike rate for Red-tailed Hawks was likely a consequence of the intensity and altitude of soaring flight. Turkey Vultures had a strike rate 23% above the mean (N = 18) when young were in the nest and Red-tailed Hawks were very close to the mean strike rate ( — 2%, N = —1). This suggested that more Turkey Vultures spend more time soaring in aircraft airspace when young were in the nest. Red- tailed Hawks, conversely, spent less time in the al- titude band in conflict with aircraft when young were in the nest than during the incubation peri- od. The seasonal variation in strike rates showed that the first assumption of the current raptor BAM is flawed. The standing populations in winter and summer do not pose a constant risk to aircraft of birdstrikes. The results show that migration is not an important factor in bringing the two species into conflict with military aircraft. A change in mil- itary flying tactics could result in aircraft routinely flying in the altitude band used by migrants. Fur- ther research is required to isolate which aspects of Turkey Vulture and Red-tailed Hawk ecology and behavior have the potential to bring them into conflict with aircraft. The equations used to cal- culate risk of a birdstrike with the study species 62 Expanded Abstracts VoL. 33, No. 1 should not seek to minimize the effect of the standing population. This will permit the BAM to be effective in identifying risk even when military tactics change. The birdstrike databases kept by many nations represent a valuable resource for identifying pos- sible ecological factors affecting the strike rate with aircraft. To be analyzed effectively, they need to be compared with other ornithological databases. The results of such tests can be used to formulate hy- potheses and establish research priorities. This is a low cost first step to solving raptor/aircraft con- flicts and establishing an improved bird avoidance model. Literature Cited Jackson, J.A. 1983. Nesting phenology, nest-site selection and reproductive success of Black and Turkey Vul- tures. Pages 245-270 in S. Wilber and J. Jackson [Eds.], Vulture biology and management. Berkeley and Los Angeles, CA U.S.A. Merritt, R.L. 1990. The bird avoidance model. World BASH Conference, Little Rock, AR U.S.A. Mindell, D.P. 1985. Temporal/spatial location of raptors [Letter]. Rep. Univ. Dayton Res. Inst., Dayton, OH U.S.A. Palmer, R.S. 1988. The Red-tailed Hawk. Handbook of North American Birds. Vol. 5. Yale University Press, New Haven, CT U.S.A. J. Raptor Res. 33(l):63-66 © 1999 The Raptor Research Foundation, Inc. RAPTOR ATTACKS ON PEOPLE James W. Parker Aerie East, EIR 3, Box 3110, Farmington, ME 04938 U.S.A. Raptors usually attack a narrow class of people, namely biologists that are approaching nests. Rap- tor biologists routinely tolerate nest-defense behav- ior, and most, when properly attired, confess to some enjoyment of a diving bird. An attack can vary from a half-hearted dive missing a person by feet, to violent hitting, usually on or near the head, by closed or opened feet, or raking or grabbing with one or more talons. It can result, depending on raptor size and temperament, in minor annoy- ance or serious lacerations, bruises, punctures, damaged eyes, torn clothing, auto accidents, and even death if complicated by factors such as heart disease or a fall. Usually the result is harmless, al- beit unexpected, but for the general public it con- veys an image of danger, of Hitchcock’s movie, “The Birds,” or of Velociraptors in Spielberg’s “Ju- rassic Park.” Media-sensationalized raptor attacks on private citizens work strongly and persistendy against re- spect for raptors, predation, and wildlife laws. Therefore, it is important that they be explained to the general public, preferably by those knowl- edgeable about raptors, managed if necessary, and be used as opportunities to educate. This paper reviews the causes and records of rap- tor attacks on people, and discusses management solutions to this problem. My background of col- lege teaching and research followed by full-time ecological education, frequently using live raptors in the public realm, leads me to approach raptor attack behavior and predation from a broad per- spective. My concern for raptor attack behavior re- sults from years studying the Mississippi Kite {Icti- nia mississippiensis) , which seems to have had its nest-defense diving publicized more than any oth- er raptor species. Records and Causes of Attacks Raptor attacks have no unifying literature and little research attention. Most accounts are in the newspapers rather than in recent ornithological lit- erature. A literature search of the Raptor Research and Technical Assistance Center (U.S. Geological Service) found only 18 references, mostly to fab- ricated accounts of attacks by eagles on adult hu- mans and children. Other accounts, by Lumley (1939), Walker and Walker (1940), and Edge (1945), refuted claims of the raptorial carnivore as a vicious, blood-thirsty predator. Mavrogordato (1965) documented a rare court conviction of a hunter who shot a falconry-trained Tawny Eagle {Aquila rapax) claiming it was about to attack his entire hunting party. Two references (Bedichek 1948, 1961) described formal military responses to eagle harassment of WWI biplanes, a situation that might today confront slow-flying, single-engine air- craft. Although there are few references to attacks on humans by diurnal raptors, Thompson (1964), Grossman and Hamlet (1964), Grizmek (1975) and Voous (1977) convey the impression that, be- cause of their scavenging in urban environments, Red and Black Kites {Milvus milvus and M. migrans) have the potential to harass people to pirate food items. The National Wildlife Federation’s Raptor Management Techniques Manual (Pendleton et al. 1987) makes no mention of raptors diving at hu- mans, but its section on transplanting nests and nest contents is applicable to the management of diving problems. Owls have more of a reputation for attacks, often vigorous. Burton (1973) highlighted the tendency for attack by Screech Owls ( Otus asio) and Strix spe- cies, and Sparks and Soper (1970) mentioned the Great Horned Owl {Bubo virginianus) as an attack- er. In sections on antagonistic behavior, Voous (1988) thoroughly documented and assessed div- ing by 12 owl species. The last two works men- tioned the prominence of attacks by owl species that have become urbanized, including the south Asian Spotted Owlet {Athene brama) . The most extensive account of attacks on people by a single bird is of Heinrich’s (1987) captive- raised Great Horned Owl. This bird accosted peo- ple to protect cached food, to obtain food objects they held, and probably because they approached Heinrich. This case demonstrates a problem poten- tially caused by release of raptors which have been improperly raised, a major concern for rehabilita- tors. 63 64 Expanded Abstracts VoL. 33, No. 1 In an evolutionary context, Newton (1979) not- ed that geographic variation in diving behavior probably correlates with variation in past treatment of raptor populations by humans. He stressed that killing of raptors which did not flee from humans at nests selected against aggressive defense behav- ior. However, the rapid development of defensive diving in urban populations of Mississippi Kites in- dicates it is often the result of raptor experience and learning. Raptor biologists often collect credible accounts of raptor attacks on private citizens. Worldwide, these would comprise a massive and fascinating data set, but there has not heen, and probably nev- er will be, a good way to compile, verify, and pub- lish these. One account (Anchorage Daily News, 1989) described a skier who, on the slopes in Jan- uary, lost most of his clothing to a Great Horned Owl in repeated, prolonged attacks. His compan- ions were not targeted. Another account involved common folklore in Bel Air, Maryland in which a captive-raised Great Horned Owl terrorized two housing developments by repeatedly landing on people to get food, with a preference for hot dogs. In a series of five letters {N. Eng. J Med. 1984, 311:1703; 1985, 312:1066-67; 313:330, 1232) brief- ly summarized in The Runner Magazine (April, 1985), several medical doctors discussed diving at Swiss joggers by Common Buzzards {Buteo buteo). Their explanations of bird behavior were invalid, although they referred to a more competent ac- count of buzzard nest defense (Fryer 1974). Such letters show a need for raptor biologists to be more involved in raptor public relations. Interesting legal and public relations problems can be generated when a raptor is killed as the result of its attack. In May, 1982, a retired deputy sheriff was hit by a nesting adult female Northern Goshawk {Accipiter gentilis) while in the woods near Wilton, Maine. Fearful and without relevant knowl- edge, he shot the bird and was pictured in the local paper holding the carcass triumphantly. He was not prosecuted, and I was prohibited from using the newspaper clipping of the shooting in a biol- ogy department education display on environmen- tal education. Most raptor attacks on humans can be explained by humans: being too near nests; being too near a disadvantaged, injured, or young raptor; approach- ing a raptor’s food cache; encountering hand- raised (imprinted) but free-flying raptors; or lead- ing, holding or wearing food or food-like objects. Emotional and sensational claims that raptors are expressing vicious, vindictive behavior should be countered vigorously and quickly. Mississippi Kites The most publicized defensive diving on humans in North America is by the Mississippi Kite, a crow- sized, migratory species that nests in 16 southeast- ern and southcentral states of the U.S. Like all North American raptors, the Mississippi Kite is pro- tected by federal (Migratory Bird Treaty Act) and state laws. It defends its nest aggressively in flocks against predators. This has led to an urban public relations problem. The following description is from Parker (1988a, 1996) unless otherwise refer- enced. During about 1945—65, Mississippi Kites in the Great Plains shifted their prairie nesting habitat from riparian trees to farm woodlots, windbreaks, and mesquite groves, all recently man-created. In the late 1970s, they became conspicuous urban nesters. Now, they nest densely by hundreds or thousands in urban areas of all sizes in hve states. Urban roosting groups of 50-100 are not unusual. Kite populations have responded to increased nest- ing habitat, and probably an increased food base stemming from agricultural activity. Shaw (1985), Gennaro (1988a), and Parker (1996) showed its ur- ban reproductive output is nearly twice the rural rate. Parker (1996) indicated that urban popula- tions showed denser nesting, more nest reuse, more yearlings in populations, and probably less threat to nests than in rural kite populations. In 1978, 28 kites were shot in Ashland, Kansas because one or more dove at people. Prosecution of the four offenders was successful and resulted in major public relations conflicts for state and fed- eral wildlife agencies and the town. One offender was a state conservation officer. Incidents of diving have increased annually in cities and towns of all sizes. In urban areas, nesting pairs favor open, park-like areas including golf courses, city parks, town squares, and residential lawns, where diving is particularly disturbing to the public. Shaw (1985), Gennaro (1988b) and Parker (1979a, 1979b, 1980) concurred that diving kites are a small minority, that those hitting people are even less frequent, and that usually only one kite from a nest dives. However, because kites are so abun- dant, and humans pass so frequendy, there are many verified accounts of diving and hitting. These include several golfers requiring stitches, two chil- March 1999 Expanded Abstracts 65 dren on bicycles struck by cars as a result of diving, an elderly woman who broke a bone when fright- ened enough to fall down steps, and a woman re- ceiving a scratched cheek leading to an eye infec- tion. Children, dogs, and people on regular routes (e.g., postmen) are frequent targets, and postal de- livery is sometimes interrupted. Subjectively, one gets the sense that kites in urban areas are more aggressive. Management Responses In 1978, I began advising local, state (Kansas, Oklahoma, New Mexico), and federal agencies (U.S. Fish and Wildlife Service, U.S. Animal Dam- age Control) in management, reduction, or elimi- nation of kite diving, as described in a number of popular, scientific, and technical publications (Parker 1979a, 1979b, 1980, 1987, 1988b, Rideout 1979, Engle 1980, Andelt 1983, Garrison 1986, Gennaro 1988a, 1988b, DiCanio 1989, Sweet 1989). The Kansas State Cooperative Extension Service and the Martin Park Nature Center in Oklahoma City have produced several educational pamphlets and newsletter articles about diving, and a large educational poster was produced in 1980 by the U.S. Fish and Wildlife Service and the author. Complaints about defensive diving come to na- ture centers, police departments and government offices. In Kansas and Oklahoma, action is taken as needed by personnel of the U.S. Animal Dam- age Control, in cooperation with state wildlife agencies and several zoos and nature centers. Per- manent metal educational signs have been posted at the Altus (Oklahoma) Air Force Base golf course, at a golf course in Qovis, New Mexico (Gennaro 1988b) and by the Martin Park Nature Center staff in Oklahoma City (Garrison 1986). Some of these warn of specific diving birds and their nests, and are placed or moved as needed each summer. My responses to diving incidents include: rapid coordination between government and private bi- ologists, educators, and managers; quick educa- tional contact with the disturbed public; and if nec- essary, removal of nests of diving kites. Nestlings or eggs (rarely) are transplanted to rural kite nests, or donated to an endangered species management program in west Tennessee (Parker 1984, Stokes 1985, Martin and Parker 1991). In New Mexico, Gennaro (1988b) developed a program with support of the New Mexico Depart- ment of Game and Fish to study and manage the state’s major kite population at Clovis, where div- ing is frequent on a golf course. He used nest re- moval but also experimented extensively with the use of three-dimensional kite models placed in trees to discourage kites from nesting in areas where diving would be a problem. The models were of some use but often only displaced nesters a short distance. This technique is also hampered by shortage of models and time to use them. Just as diving by Mississippi Kites is apparently a permanent problem, continued urbanization of raptor populations will increase chances for future attacks on humans by other raptor species. Attacks on humans can be expected to continue for those species now involved, and could develop for spe- cies like the Merlin (Oliphant and Haug 1985, Palmer 1988). Information on the Mississippi Kite and other raptors known to dive at humans should be used by private and government biologists and educators to manage conflicts. Literature Cited Andelt, W.F. 1983. Mississippi Kites. Coop. Ext. Sen, Univ. Nebraska, Lincoln, NE U.S.A. Bedichek, R. 1948. Golden Eagle: airplane hater. Sci. Di- gest 23:56-60. . 1961. Adventures with a Texas naturalist. Dou- bleday Press, New York, NY U.S.A. Burton, J.A. 1973. Owls of the world. Eurobook Ltd , London, U.K. Dicanio, M. 1989. The aerial gymnastics of the Mississip>- pi Kite. Pages 19-21 in The facts on file scientific year- book 1989. Facts on File, Inc., New York, NY U.S.A. Edge, R. 1945. Eagles in wonderland. Hawk Mountain Sanctuary Assoc., New York, NY U.S.A. Engle, M.C. 1980, Mississippi Kite strikes human being. Bull. Okla. Ornith. Soc. 13:21-22. Fryer, G. 1974. Aggressive behavior by buzzards at nests. Brit. Birds 67:238-239. Garrison, N. 1986. Nesting Mississippi Kites. Outdoor Oklahoma 42:32-37. Gennaro, A.L. 1988a. Breeding biology of an urban pop- ulation of Mississippi Kites in New Mexico. Pages 188- 190 in R.L. Glinski, B.G. Pendleton, M.B. Moss, M.N. LeFranc, Jr., B.A. Millsap and S.A. Hoffman [Eds.], Proc. Southwest Raptor Management Symp. and Workshop. Nad. Wildl. Fed. Tech. Ser. No. 11. Wash- ington, DC U.S.A. . 1988b. Extent and control of aggressive behavior toward humans by Mississippi Kites. Pages 249-252 m R.L. Glinski, B.G. Pendleton, M.B. Moss, M.N. Le- Franc, Jr., B.A. Millsap and S.A. Hoffman [Eds.], Proc. Southwest Raptor Management Symp. and Workshop. 66 Expanded Abstracts VoL. 33, No. 1 Natl. Wildl. Fed. Tech. Ser. No. 11. Washington, DC U.S.A. Grossman, M.L. and J. Hamlet. 1964. Birds of prey of the world. Bonanza Books, New York, NY U.S.A. Grizmek, B. 1975. Grizmek’s animal life encyclopedia. Van Nostrand Reinhold, New York, NY U.S.A. Heinrich, B. 1987. One man’s owl. Princeton Univ. Press, New York, NYU.S.A. Lumley, E.D. 1939. The two eagles of North America. Emerg. Cons. Comm, Unit III, Publ. 78. Martin, K. and J. Parker. 1991. Mississippi Kites reborn in Tennessee. Tenn. Cons. 57:5-10. Mavrogordato, J.G. 1965. Case of the shot Tawny Eagle. Falconer 4:233-235. Oliphant, L. and E. Haug. 1985. Productivity, popula- tion density and rate of increase of an expanding Mer- lin population. Raptor Res. 19:56-59. Newton, I. 1979. Population ecology of raptors. Buteo Books, Vermillion, SD U.S.A. Palmer, R.S. 1988. Handbook of North American birds. Diurnal Raptors (Part 2). Vol. 5. Yale Univ. Press, New Haven, CT U.S.A. Parker, J.W. 1979a. The Mississippi Kite. Kansas Fish and Game 36:4—8. . 1979b. About those kites. Kansas Fish and Game 36:5-6. . 1980. Kites of the prairies. Bird Watcher’s Digest 86-95. . 1984, Transfer of nestling Mississippi Kites from Kansas to Tennessee. Project narrative, correspon- dence, reports. Center for Environmental Research and Education, Univ. Maine Farmington, Farmington, ME U.S.A. . 1987. Urban-nesting Mississippi Kites: history, problems, management and benefits in L.W. Adams and D.L. Leedy [Eds.], Integrating man and nature in the metropolitan environment. Proc. Natl. Symp. on Urban Wildl. Natl. Inst, for Urban Wildl. Colum- bia, MD U.S.A. . 1988a. Mississippi Kite. Pages 166—186 in R.S Palmer [Ed.], Handbook of North American birds. Diurnal Raptors (Part 1), Vol. 4. Yale Univ. Press, New Haven, CT U.S.A. . 1988b. The ace dive-bomber of the prairie is a terror on the green. Smithsonian 19:54-63. . 1996. Urban ecology of the Mississippi Kite. Pages 45-52 in D.M. Bird, D.F Varland and J.J. Negro [Eds.], Raptors in human landscapes. Academic Press, London, U.K. Pendleton, B., B. Millsap, K. Cline and D. Bird. 1987. Raptor management techiques manual. Natl. Wildl Fed. Washington, DC U.S.A. Rideout, D.W. 1979. Plains gliders. Texas Parks and Wild- life 37:3-5. Shaw, D.M. 1985. The breeding biology of urban-nesting Mississippi Kites {Ictinia mississippiensis) in west central Texas. M.S. thesis, Angelo State Univ., San Angelo, TX U.S.A. Sparks, J. and T. Soper. 1970. Owls. Their natural and unnatural history. Taplinger Publ., New York, NY U.S.A. Stokes, J. 1985. Mississippi Kite. Endangered acrobat of Tennessee’s skies. Tenn. Wildl. 8:13-17. Sweet, M.J. 1989. Kites and the Northern Harrier. Pages 32-41 in Proc. Midwest Raptor Management Sympo- sium and Workshop. Natl. Wildl. Fed. Sci. Tech. Ser. No. 12, Washington, DC U.S.A. Thompson, A.L. 1964. A new dictionary of birds. Mc- Graw-Hill, New York, NY U.S.A. Voous, K.H. 1977. Three lines of thought for conserva- tion and eventual action in Proc. World Conference on Birds of Prey, ICBP. Taylor and Francis, Hamp- shire, U.K. . 1988. Owls of the northern hemisphere. MIT Press, Cambridge, MA U.S.A. Walker, L. and M. Walker. 1940. Headlines on eagles. Nat. Mag. 33:321-323. J. Raptor Res. 33(1) :67-72 © 1999 The Raptor Research Foundation, Inc. THE EXTENT, COST AND CONTROL OF LIVESTOCK PREDATION BY EAGLES WITH A CASE STUDY ON BLACK EAGLES {AQUILA VERREAUXII) IN THE KAROO Robert A.G. Davies Mammal Research Institute, University of Pretoria, Pretoria 0001, South Africa Intense persecution of predators in the sheep- farming Karoo region of South Africa has been suggested as the reason for irruptions of rock hy- rax (Procavia capensis) which have caused signifi- cant damage to vegetation resources in the past (Thomas 1946, Kolbe 1967, Rubidge in Kolbe 1983) . I carried out a 5-yr field study in and around the Karoo National Park (KRNP) near Beaufort West to assess the costs and benefits of Black Eagles {Aquila verreauxii) to Karoo farmers (Davies 1994). This paper summarizes the harm that Black Eagles may cause on farmland, and this is discussed in relation to livestock predation by eagles worldwide, and it appraises possible management solutions for problem situations. Predators can cause major losses to livestock ranching operations (O’Gara et al. 1983). Preda- tors may only remove a small percentage of sheep flocks, hut these fractions may amount to great fi- nancial loss when applied to nationwide livestock numbers (U.S. Fish and Wildlife Service 1978, Tex- as Crop and Livestock Reporting Service 1979, Lawson 1989). Bounty systems, that resulted in the destruction of millions of predators, have been in- voked to avert such losses, but they have been largely ineffectual, and most have now been dis- continued (Hey 1959). Large eagles have not been exempt from bounty systems and they have been persecuted in all the m^or sheep-farming regions where they occur (Brown 1976). Kill rates of Wedge-tailed Eagles {Aquila audax) in Australia (Leopold and Wolfe 1970) were held to be the highest for any large raptor worldwide (Brown 1975), but they were much lower than kill rates of Black and Martial {Polemaetus bellicosus) Eagles claimed by farmers in parts of the Karoo in the 1960s (Siegfried 1963). Has such persecution been based on any factual evidence of eagles killing livestock? Golden {Aquila chrysaetos) and Crowned {Stephanoaetus coronatus) Eagles have killed prey (including domestic sheep) weighing 20-50 kg (Lehti 1947, Cooper 1969, Bruns 1970, Skogland 1974, Svendsen 1980, Steyn 1982, O’Gara et al. 1983, Bergo 1987). Large ea- gles are, therefore, capable of killing domestic sheep up to about half adult size, so the issue ap- pears to be not whether they kill domestic lambs, but to what extent does this occur and under what circumstances. Most ranchers maintain that only small lambs (<10-d old) are vulnerable to eagle attack (Arnold 1954, Wiley and Bolen 1971, Palmer 1983). It is immature eagles that most often become involved in livestock depredations (Foster and Crisler 1979, O’Gara 1978). The Golden Eagle is the chief of- fender in the northern hemisphere. Only three species of Haliaeetus have been recorded killing lambs in North America, Europe and Australia, but there is little evidence to support these accusations. In Australia, lamb-killing by Wedge-tailed Eagles has been confirmed (Brooker and Ridpath 1980) and, in Africa Martial Eagles (plains) , Black Eagles (mountains) and Crowned Eagles (forests) are reg- ularly accused of killing lambs, with some confir- mation that they do. There is little overlap between the ranges of large, forest-dwelling eagles and the major sheep farming regions of the world. Domestic lamb remains comprised 1.1% of the 3586 prey items collected beneath Black Eagle nests in and around the KRNP, and, 1.6% of those collected solely beneath farm nests. Domestic lambs comprised a similar proportion of 389 prey items delivered to nests as monitored by time-lapse photography, and of sightings of fresh prey on the nest. With an estimate of prey capture rate (173 prey/pair/yr) , this indicated that a resident pair of Black Eagles normally consumed three lambs per year on Karoo farmland. In other regions of the Cape, Black Eagles may consume more domestic lambs since they comprised 8% of prey remains collected in the heavily-vegetated Eastern Cape (Boshoff et al. 1991). Bolen (1975) observed that livestock comprised a greater portion of Golden Eagle diet in areas of thick brush in Texas, where 67 68 Expanded Abstracts VoL. 33, No. 1 natural prey was highly abundant but presumably less vulnerable. While these collections of eagle prey indicate that domestic livestock represent a very small portion of large eagle diets, they should, however, be interpreted cautiously. They only re- flect diet of breeding birds during the nesting sea- son and we know that nonbreeding eagles cause more harm. The collections may also be biased be- cause remains of large animals like lambs tend to decompose more slowly nor do they indicate whether lambs delivered to nests were killed or scavenged (Matchett and O’Gara 1987). Lockie (1964) showed that only three of 10 assayable lamb carcasses brought to Golden Eagle nests were killed by eagles. I observed resident Black Eagles for 55 d. During this time, I did not see any attacks on livestock, but I observed the eagles scavenging on domestic sheep twice. During 80 d of observation on Merino sheep as part of another study, I witnessed regular attacks by an immature Martial Eagle on various natural prey, but the eagle ignored 40 vulnerable Merino lambs which occasionally bedded directly beneath one of the eagle’s roost trees. Birds, in- cluding raptors, are known to become ‘imprinted’ or ‘wedded’ to particular food types if these are fed to the exclusion of all else during sensitive de- velopmental phases in the nestling period (Wood- ford 1966, Rabinowitch 1969, Hess 1973, Immel- mann 1975). Infrequent predation on domestic lambs by eagles in the Karoo, despite high avail- ability and vulnerability of this prey, may be ex- plained if most young eagles are raised on a diet of natural prey items. Greater incidence of eagle predation on goat kids rather than sheep lambs has been attributed to poor attendance by nannies (Glover and Heugly 1970) and isolation in rough terrain (Nass et al. 1984), but goat kids bear a clos- er resemblance to juvenile antelope which are reg- ularly killed by large eagles. I interviewed farmers during 30 visits to farms in the central Karoo region, and some claimed ex- tremely high kill rates of eagles in certain low-in- come districts. Despite this, there was no evidence for a decline in Black Eagle numbers in the Karoo so there is probably a large ‘floating population’ of nonbreeders. The majority of farmers were pre- pared to tolerate resident eagles until lamb killing was suspected. A minority of farmers took active steps to encourage eagles on their farms through the provision of artificial nest sites and rehabilita- tion of injured birds. Approximately half of the 37 farmers spoken to reported no lamb losses to ea- gles; 27% reported occasional losses and 24% re- ported significant losses including a few eyewitness accounts of kills. Twelve questionnaire surveys of ranchers (world- wide) indicated that most ranchers believed that predators removed nearly 7% of lambs born (9% of lambs born were thought to die of other caus- es) (Fig. 1) . However, estimates of predation are of- ten exaggerated in these surveys (Nesse et al. 1976, Armentrout 1980, Boshoff 1980, Hewson 1981). Field necropsies conducted on lamb carcasses found in lambing camps gave reliable data on caus- es of death and whether lambs killed by predators were dying from other causes (Rowley 1970, Wiley and Bolen 1971, Bowns et al. 1973, Brown 1976, Nesse et al. 1976, Tigner and Larson 1977, 1981, O’Gara 1978, Wade and Bowns 1980). Massive sub- cutaneous hemorrhaging surrounding irregularly- spaced talon punctures on the neck and upper back are prime indicators for eagle-killed lambs. Carcass inspections are considered to be the only realistic method for quantifying livestock predation by eagles and also provide good opportunities for constructive interaction with ranchers. I only ex- amined 23 carcasses on visits to farms where eagles were allegedly killing lambs. None of these lambs were found to have been killed eagles. I also ob- tained data from 44 studies involving about 30 000 necropsies worldwide (Fig. 1). These results indi- cated that most ranching operations experience very low losses to predation but at a few ‘problem situation’ ranches very high losses probably occur. Necropsies show that predators remove only an av- erage of 4.9% of lambs born as compared to the average of 13.7% lambs that die from nonviolent mortality factors. Evidently ranching operations in Australia and especially South Africa and Scotland experience relatively low losses of lambs to predators; whereas North American operations experience relatively high losses (Fig. 2). This can be attributed to se- vere problems with coyotes {Canis latrans) in some parts of the U.S., and to the fact that inviable lambs (already dying to other causes) were not distin- guished in most North American estimates of pre- dation. Certain investigations provided data on the relative involvement of different predators. It is clear that wild and domestic canids cause the most damage to ranching operations. In South Africa, caracals {Felis caracal) cause significant losses, and in Australia feral pigs {Sus scrofa) are significantly March 1999 Expanded Abstracts 69 FREQUENCY HISTOGRAM FOR INVESTIGATIONS SHOWING PE R CENT LAMBS KILLED BY PREDATORS