%lr/ -■oPl.Fto (t) t/A) Florida Field Naturalist PUBLISHED BY THE FLORIDA ORNITHOLOGICAL SOCIETY kj FLORIDA ORNITHOLOGICAL SOCIETY Founded 1972 Officers President: FRANCES C. JAMES, Department of Biological Science, Florida State University, Tallahassee, FL 32306-1100. E-mail: james@bio.fsu.edu Vice President: JOYCE King, 11645 69th Way N., Largo, FL 33773. Secretary: PAMELA J. BOWEN, 309 Moonstone Dr., East Palatka, FL 32131. E-mail: pjbowen@aol.com Treasurer: DEAN Jue, 3455 Dorchester Court, Tallahassee, FL 32312-1300. E-mail: djue@admin.fsu.edu Editor, Florida Field Naturalist: JEROME A. JACKSON, Whitaker Center, Arts & Sci- ences, Florida Gulf Coast University, 10501 FGCU Blvd. South, Fort Myers, FL 33965. Ex Officio: Immediate Past President: Peter G. Merritt, 8558 SE Sharon St., Hobe Sound, FL 33455. Directors, Terms Expiring Spring 2005 JUDITH B. Buhrman, 6123 113th Street, #504, Seminole, FL 33772-6846 Terry J. 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The Florida Ornithological Society web site can be found at www.fosbirds.org THIS PUBLICATION IS PRINTED ON NEUTRAL PH PAPER Florida Field Naturalist PUBLISHED BY THE FLORIDA ORNITHOLOGICAL SOCIETY Vol. 33, No. 1 February 2005 Pages 1=27 Florida Field Naturalist 33(1):1-14, 2005. POPULATION GROWTH OF MONK PARAKEETS IN FLORIDA Stephen Pruett-Jones1, James R. Newman2, Christian M. Newman2 and James R. Lindsay3 Corresponding author: Department of Ecology and Evolution, University of Chicago, 1101 East 57th St., Chicago, Illinois 60637 E-mail: pruett-jones@uchicago.edu 2Pandion Systems, Inc., 5200 NW 43rd Street, Suite 102-314 Gainesville, Florida 32606 3Florida Power & Light Company 700 Universe Blvd., Juno Beach, Florida 33408 Abstract.— We summarize records of Monk Parakeets ( Myiopsitta monachus ) in Florida from Christmas Bird Counts (CBCs) from 1972 to 2003. On the 2002/2003 CBC a total of 2884 parakeets were counted at 22 localities in 16 counties, and over five broad geographical regions in Florida. On the 2002/2003 CBC the population of Monk Para- keets in Florida comprised 69.4% of the records of this species on CBCs nationwide, a percentage that has remained relatively stable over the last 15 years. The population of Monk Parakeets in Florida is growing at an exponential rate across the state generally, and within each of the four geographical regions where it is common. Across the entire state, the current intrinsic rate of population increase, r, equals 0.094 and is associated with a population doubling time of approximately 7.5 years. Given the apparently ideal conditions in Florida for a species such as the Monk Parakeet, and the observed exponen- tial rate of population increase, this species will likely continue its range expansion and dramatic population increase in Florida for the foreseeable future. Problems associated with Monk Parakeet nests on electrical utility structures are also likely to increase. In some regions of the United States, particularly in California and Florida, introduced parrots are an increasingly common part of the lo- cal avifauna. In southern California, for example, there are now 10 species of naturalized parrots (i.e., those that have established breed- ing populations) and population estimates put the number of individu- als at 2,500 to 3,000 (all species combined; Garrett 1997). In Florida, the numbers are substantially larger. On the 2002/2003 Christmas Bird Count a total of 4,169 individuals of 22 species of parrots were re- ported for Florida. Florida’s Breeding Bird Atlas ( http ://w w w. wi 1 dfi or- 1 2 FLORIDA FIELD NATURALIST ida.org/bba/) provides species accounts for 22 species of parrots known to breed in Florida, plus an additional three species known to occur in Florida but for which breeding has not been established. Combining the data from California and Florida, at least 26 species of parrots are now naturalized (or suspected of being naturalized) in the contiguous United States. Compared with the known number of naturalized par- rots in the United States just 17 years ago (nine species at that time; Lever 1987), it appears that approximately one new species of parrot becomes naturalized here each year. The most abundant of these species is the Monk Parakeet ( Myiop - sitta monachus ). When Monk Parakeets established breeding colonies in the United States is unclear because of the uncertainty over when and where birds were released or escaped. The first confirmed sighting was in 1967 in New York City (Lever 1987), and the species was breed- ing there shortly thereafter (Bull 1973). In Florida, the species was breeding in Miami by 1969 and possibly earlier (Owre 1973). Given multiple sightings of free-flying Monk Parakeets in the United States during the late 1960s (Bull 1973, Freeland 1973, Owre 1973, Simpson and Ruiz 1974), and the wide distribution of these sightings (from New York to Florida), it appears likely that the species became naturalized in multiple localities simultaneously as the result of multiple acciden- tal or purposeful releases. Although most species of naturalized parrots comprise relatively benign, if non-native, additions to local avifaunas, this is not the case with Monk Parakeets. There are several reasons for interest and con- cern in this species. First, the Monk Parakeet is the only species of par- rot to build its own nest and it exhibits cooperative breeding (Sol et al. 1997, Eberhard 1998, Spreyer and Bucher 1998). Second, although most parrot species are locally restricted in distribution within the United States, Monk Parakeets are now widely distributed, from Ore- gon to New York in the north and from Florida to Texas in the south, and their population is growing exponentially (Van Bael and Pruett- Jones 1996, Pruett-Jones and Tarvin 1998). Third, there is concern that this species may become an agricultural pest, as it is reported to be in its native range (Bump 1971, Bucher and Bedano 1976; but see Bucher 1984). Perhaps most importantly, in several states, notably Connecti- cut, Florida, Texas, New York, and Illinois, the Monk Parakeet is caus- ing electrical reliability problems and public safety issues because of its habit of building nests on electrical structures, causing power outages, electrical fires, and disruption of electrical service to customers. Because of its potential to become an agricultural pest, the Monk Parakeet was the focus of an eradication program by the United States Fish and Wildlife Service (USFWS) in the 1970s. This program reduced the numbers of Monk Parakeets at that time by approximately one- Pruett- Jones etal, Monk Parakeets in Florida 3 half (Neidermyer and Hickey 1977). Since 1 975. the year that the US- FWS removal program ended, numbers of Monk Parakeets have recov™ ered and the species has exhibited a dramatic population expansion to levels far above the pre-control numbers in the early 1970s (Van Bael and Pruett-Jones 1998, Pruett-Jones and Tarvin 1998). Monk Para- keets have exhibited a similar population expansion and increase in Europe, where it is also a naturalized species (Sol et ah 1997). Given that Florida is home to more than half of all Monk Parakeets presently breeding in the United States (Van Bael and Pruett-Jones 1996), an examination of the distribution and population growth of the species in Florida specifically seems warranted. Here we present such an analysis, summarizing population counts in Florida since 1972, for both the state as a whole and for specific geographic regions within the state. We also compare population growth of Monk Parakeets in Flor- ida with trends nationwide, as well as in other states where the species is common. Methods We summarized Christmas Bird Count records from every locality in the United States where Monk Parakeets have been recorded from 1972 to 2003 (the 2002/2003 count). These data were obtained from National Audubon Society’s Christmas Bird Count web site: http://www.Audubon.org/bird/cbc/. Both total number of birds recorded and the number of “party hours” (the total number of person-hours spent counting birds in the count circle) were tabulated. Knowing the number of party hours on each count provides a method of adjusting counts for the relative effort involved. Although some data from 1972 to 1975 are presented here, our statistical analyses focused on data collected during the period 1976 to 2003. Inclusion of data from 1972 to 1975 would have biased results because the population was being purposefully reduced during that time. There are many methods of analyzing population data, but one of the most widely ac- cepted is to determine what type of growth model the data fit. Two common models are the exponential growth model and logistic growth model. Populations experiencing ex- ponential population growth are increasing in size rapidly, and at an increasing rate. Populations exhibiting logistic growth have reached or will soon reach an equilibrium population size (the carrying capacity of the environment) and then tend to fluctuate around this mean value over time. The standard equation defining exponential growth is Nt+1 = Nter^ where Nt+1 is the population size at time t+1, Nt is the population size at time t, r is the intrinsic rate of population growth, t is the time interval, and e is the natural logarithm base. To de- termine whether a population is growing exponentially, the standard procedure is to plot the natural logarithm (In) of population size against time and to test whether this relationship is statistically significant. A significant regression suggests that the popu- lation growth fits an exponential model. To calculate the intrinsic rate of population growth, r, the equation above defining exponential growth rate can be rewritten as r - (lnNt+l - lnNt)/t. To calculate the time interval for a population to double in size, the equation above defining r can be rewrit- ten as t = ln2 /r. We calculated r, and the population doubling time for each one-year in- terval beginning in 1976 for the United States, Florida, and various regions in Florida, 4 FLORIDA FIELD NATURALIST and then averaged the yearly values for the period 1976-2003 and for 1989-2003 (the last 15 years). Monk Parakeets are not equally common across all areas of Florida, and we sought to examine population growth for each area separately. The Florida Counties Map {http: / / www.floridacountiesmap.com ) defines eight broad geographic regions within the state as follows: Northwest, North Central, Northeast, Central West, Central, Central East, Southwest, and Southeast (Appendix 1). For each CBC locality reporting Monk Parakeets, we noted the county and the geographic region of that locality. Results In Table 1 we summarize the numbers of Monk Parakeets recorded on CBCs from 1972 to 2003 for the United States as a whole, as well as for Florida, Connecticut, Texas, and Illinois, the four states where these parakeets are most common. Data for Connecticut, Texas, and Il- linois are presented for comparison with Florida. Monk Parakeet num- bers have steadily increased over time, although across states the timing of the initiation of the increase varied. In Florida the increase began in the 1970s. In Texas it began in the early 1980s, in Connecticut the late 1980s, and in Illinois the early 1990s. Florida has, from the beginning of the species expansion, had most of the individual birds present in the United States. Over the last 15 years (1989-2003), the proportion of the total number of birds in the contiguous United States recorded in Florida has ranged from 66.6% to 79.9%, with an average of 72.5%. Both the actual numbers of parakeets recorded on CBCs (see Table 1) and the number of birds corrected for effort (party hours; Fig. 1) have increased in Florida. The regression of birds/party hour (In) against time for Florida (Fig. 2) is statistically significant (df = 1, 26, F = 190.865, P < 0.0001), suggesting that the population of Monk Para- keets is growing at an exponential rate across the state as a whole. The population of Monk Parakeets across the United States as a whole is also increasing exponentially (df = 1, 26, F - 299.393, P < 0.0001)) but this is not just a consequence of the records from Florida. When we ex- clude the Florida data from other records of Monk Parakeets, we still observe an exponential rate of population growth for the United States generally (df - 1, 26, F = 73.146, P < 0.0001). We examined the CBC records separately for each geographical re- gion in Florida (Table 2). Monk Parakeets do not occur, or are rare, in the Northwest, North Central, Northeast, and Central East regions, but are common to abundant in the other four regions, the Central, Central West, Southwest, and Southeast regions (see Table 2). For each of these four regions where the species is now regularly recorded, the regression of birds/party hour (In) by time is statistically significant (Central: df = 1, 19, F = 17.229, P = 0.0005; Central West: df = 1, 25, F = 322.183, P < 0.0001; Southeast: df = 1, 26, F = 59.797, P < 0.0001; Pruett- Jones etal. — Monk Parakeets in Florida 5 Table 1. Number of Monk Parakeets recorded on Christmas Bird Counts in the United States as a whole, Florida, and three other representative states where the parakeets are currently common. Region Year United States combined Florida Connecticut Texas Illinois 1972 28 0 0 0 0 1973 67 0 0 0 0 1974 46 6 0 2 0 1975 23 5 3 2 1 1976 32 22 0 1 4 1977 22 12 0 0 0 1978 31 26 0 0 0 1979 16 10 0 0 0 1980 46 35 0 0 0 1981 59 56 0 0 0 1982 44 31 0 3 4 1983 83 60 0 5 0 1984 73 66 0 5 0 1985 165 149 0 12 0 1986 310 272 8 18 0 1987 257 210 0 18 0 1988 467 381 11 51 2 1989 442 308 40 60 0 1990 701 560 70 60 0 1991 871 610 195 60 4 1992 1219 933 174 74 1 1993 1343 1035 196 75 5 1994 1471 1079 122 131 35 1995 1816 1174 238 289 55 1996 2342 1815 308 134 31 1997 1782 1255 293 108 35 1998 2321 1634 454 135 16 1999 2681 1779 641 165 67 2000 3147 2252 569 124 105 2001 3205 2454 499 123 90 2002 4243 3041 908 121 66 2003 4158 2884 799 230 85 Southwest: df = 1, 6. F = 12.234, P = 0.129). The overall exponential growth rate of Monk Parakeet populations across Florida thus seems a consequence of exponential growth rates in each of the four regions where it has established large breeding populations. We calculated the intrinsic rate of population growth and popula- tion doubling times for the United States as a whole, for Florida, and for each of the four regions in Florida where Monk Parakeets are cur- rently common (Table 3). These data reveal several important points. First, despite the fact that Florida supports most of the Monk Para- 6 FLORIDA FIELD NATURALIST 3 o X >> tr 05 Ql CO T5 CD 03 T3 1.6 1.4 1.2 1 .8 .6 .4 .2 0 1975 1980 1985 1990 1995 2000 2005 Year Figure 1. Plot of Birds/Party Hour for Florida since 1976. keets in the United States, the populations in areas outside Florida are growing even faster than the population in Florida, leading to a higher intrinsic growth rate (0.119) in the United States generally than in Florida specifically (0.094). Second, across the four geographic regions of Florida, the intrinsic rate of population growth varies with overall population size in that region. If we rank regions by intrinsic rate of population growth, the Central West region is followed by the South- east, Central, and lastly the Southwest regions. This is the same rank- ing if we rank these regions by population size (see Table 3), suggesting that the larger the population of Monk Parakeets becomes in a region, the faster the rate of population growth. This is further support of the finding that these populations are growing exponentially, as exponen- tial growth is characterized by an ever-increasing rate of population growth. Third, and somewhat counter to the previous finding, for each of the areas considered in our analysis (see Table 3), rates of population growth have slowed slightly over the last 15 years relative to the entire period of 1976-2003. Despite the regional variation of population growth rates, across Florida as a whole, the population doubling time is between 7.37 and 7.79 years (depending on the time period consid- ered; see Table 3) suggesting that, based on this analysis, the numbers of parakeets residing in Florida will double in less than eight years. One of the difficulties of interpreting CBC data (see Discussion) is that it is often difficult to know what percentage of birds present in any area are counted on the CBC for that area. For Monk Parakeets in Pruett- Jones etal. — Monk Parakeets in Florida 7 Year Figure 2. Regression of ln(Rirds/Party Hour) for Florida since 1976. This re- gression is statistically significant, suggesting that the population of Monk Parakeets is growing exponentially in Florida. Florida, there are data for one year that allow us to examine this issue. The Monk Parakeet Survey (Bill Pranty, http ://www.monkparakeet. com/index2.htm) completed a survey of all known nests in Florida and counted birds in the areas of those nests. The survey results for eight counties (the counties for which it was believed that all nests present were known) in Florida in 1999 are presented in Table 4, along with the numbers of parakeets recorded from these counties on the 100th CBC (1999/2000). Overall, 256 parakeets were recorded in the surveys and 203 (79.3%) parakeets were reported on the CBCs. For most coun- ties, as expected, the number of birds reported on the CBCs is less than the number recorded on the field survey. We do not know the explana- tion for the large discrepancy in this trend that exists for Kissimmee Valley On the 99th CBC, just seven birds were reported from Kissim- mee Valley, and on the 101st CBC, 52 birds were reported. If we ex- clude Osceola County (and the Kissimmee Valley CBC) from our comparison, then 238 birds were recorded on the field survey and 99 (41.6%) birds were reported on the CBCs for those areas. Another com- parison that can be made is the total number of birds recorded on all of the field surveys in 1999 from the Monk Parakeet Survey versus the to- tal number of birds reported on the CBCs from Florida. Bill Pranty (http://www.monkparakeet.com/index2.htm) reports that a total of 3300 Monk Parakeets were recorded in 1999. For the 100th CBC (1999/ 8 FLORIDA FIELD NATURALIST Table 2. Number of Monk Parakeets recorded on Christmas Bird Counts in each geographical region of Florida during the last 15 years. See Appendix 1 for tabulation of counties in each region. Region in Florida Year North- west North Central North- east Central West Central Central East South- west South- east 1989 0 0 0 139 4 0 0 165 1990 0 1 0 149 4 0 0 406 1991 0 0 5 212 5 0 0 388 1992 0 0 6 503 10 0 0 414 1993 0 0 0 636 15 0 1 383 1994 0 0 0 753 1 0 0 325 1995 0 0 5 744 0 0 0 425 1996 0 0 0 1272 6 0 0 537 1997 0 0 0 839 13 0 57 346 1998 0 0 0 947 19 0 55 613 1999 0 0 2 1362 9 0 67 339 2000 0 0 0 1520 202 1 24 505 2001 0 0 0 1832 90 0 72 460 2002 0 0 8 1833 166 0 96 938 2003 0 0 9 2038 152 0 68 617 2000) a total of 2252 (68.2%) Monk Parakeets were reported on the CBCsfor all of Florida. Another difficulty in using population estimates from CBCs to cal- culate total population size is that it is often difficult to know what pro- portion of a species distribution is encompassed by the CBC count circles. For the year 2001, we have one estimate of this parameter from Dade and Broward counties. During 2001, staff of Florida Power and Light counted a total of 1069 nests on utility structures in these coun- ties. We overlaid the CBC count circles for Dade and Broward counties on a map of those counties and found that 220 (20.6%) of the nests were included in the area counted. Discussion Records from Christmas Bird Counts provide estimates of winter population size of a particular species, but interpretation of such records must be made with caution. Such records are relatively poor at estimating a species total population size, but much better at tracking long-term trends in population numbers of a species. Our use of CBC records follows the latter of these two objectives, specifically to ask whether the population of Monk Parakeets is expanding, contracting, or remaining stable. Based on our analysis here, there seems only one reasonable conclusion. Monk Parakeets are expanding their distribu- Pruett- Jones etal. Monk Parakeets in Florida 9 Table 3. Mean values of intrinsic growth rates (r) of Monk Parakeet populations calculated, for the periods 1976-2003 and 1989-2003 (last 15 years) for various regions, and the ’‘population doubling time5* associated with these values of r. Region 1976-2003 1989-2003 r Time for population to double in size r Time for population to double in size United States (including Florida) 0.119 5.82 0.104 6.66 United States (excluding Florida) 0.132 5.25 0.116 5.97 Florida 0.094 7.37 0.089 7.79 Central Florida 0.056 12.38 0.040 17.33 Central West Florida 0.168 4.13 0.127 5.56 Southeast Florida 0.124 5.59 0.083 8.35 Southwest Florida 0.043 16.12 0.043 16.12 tion in Florida, their population size is growing exponentially, and the population is currently doubling every seven to eight years. Although our efforts here are not focused on estimating the total population size of Monk Parakeets in Florida, this is obviously an im- portant issue. The total size of the population of Monk Parakeets in Florida is obviously much larger than the numbers counted on CBCs. To estimate total population size, we need values for two parameters: the proportion of the total parakeet population that is covered by the CBC count circles and the proportion of birds resident in the area cov- ered by the count circle that is actually counted. We do not have precise data on either parameter. Based on comparisons detailed in our Re- sults, we can use as a first approximation the value of 20.6% as the pro- Table 4. Comparison of Monk Parakeets counted on the 100th Christmas Bird Count (1999/2000) with field surveys in which all nests in eight counties were mapped. County Number of nests3 Number of birds3 Birds recorded on 100th CBC Brevard 8 18 1 Citrus 2 27 19 Lee 21 78 24 Orange 1 2 0 Osceola 9 18 104 Pasco 43 104 55 Seminole 1 6 0 St. Johns 2 3 0 Totals 87 256 203 “Data from the Monk Parakeet Survey (http://www.monkparakeet.com/index2.htm). 10 FLORIDA FIELD NATURALIST portion of the parakeet population that is covered by the CBC count circles. With respect to the proportion of birds resident in an area that is actually counted on the CBCs, we had three estimates: 41.6%, 68.2%, and 79.3% (see Results). These values lead us to the following calcula- tions. On the 2002/2003 CBC a total of 2,884 Monk Parakeets were counted. If the CBC count circles cover 20.6% of the total population of parakeets in Florida, and if 79.3%% of the parakeets resident in the count circles are actually counted, we can estimate the total population size of Monk Parakeets in Florida as 2,884/(0.206 x 0.793) = 18,025 birds total. In contrast, if the CBCs count is just 41.6% of the parakeets resident in an area, we can estimate the total population size of Monk Parakeets in Florida as 2,884/(0.206 x 0.416) = 32,044 birds total. The range of these two values, 18,025 and 32,044, illustrates the need for additional data before we can accurately estimate total population size. Nevertheless, these two values also estimate approximate mini- mum and maximum values for the current population size. The Monk Parakeet has a number of characteristics that appear to be related to, or have facilitated, its rapid population expansion in Florida and elsewhere. First, it builds its own nest, unlike other parrots, and is thus not dependent on large tree hollows or other similar nesting sites. Monk Parakeets appear to be able to construct a nest on virtually any surface, from trees, to man-made towers, utility poles, the frame of a bas- ketball hoop, and hollow steel tubes supporting lights. Second, the spe- cies also has an extremely diverse diet, and an ability to adapt to new foraging situations. Monk Parakeets appear to be able to eat any vegeta- tive matter, from fruits, grains, and seeds, to other plant parts. In Illinois, the species diet changed dramatically over the year as various food items became available (South and Pruett-Jones 2000). During the coldest win- ter months in Chicago, January and February, Monk Parakeets were able to subsist on a diet comprised entirely of birdseed obtained at backyard bird feeders. In Connecticut, Monk Parakeets have been observed feeding on mud flats along the coast during winter. Although perhaps less impor- tant in Florida than elsewhere, this variable and adaptable diet appears directly related to the fact that Monk Parakeets can thrive in areas with a cold winter climate. Finally, the species is highly gregarious and ap- pears to have developed and adapted to an association with humans, which appears unlike their behavior in the wild. The association with hu- mans has both a positive and negative result. The positive result is that such an association may make it less likely that the species will expand into rural, agricultural areas where it could lead to agricultural damage. The negative result is that this association will likely permit the species to continue its population expansion. Also, this association is contribut- ing to the current situation of Monk Parakeets causing economic damage in areas where the birds nest on electrical utility structures. Pruett- Jones etal.— Monk Parakeets in Florida 11 The mild climate in Florida and the seemingly unlimited potential nesting sites in Florida might suggest that Monk Parakeets should do better there than elsewhere, and to be sure Florida is home to approx- imately 60% of all Monk Parakeets in the United States. Nevertheless, the populations of this species outside of Florida are expanding at a rate that is comparable to that observed in Florida (see Table 3), sug- gesting to us that it is possible that other states will eventually have the number of Monk Parakeets that are currently seen in Florida. The Monk Parakeet is an invasive species, and its success as such led to its designation of the “Invasive Species of the Month” for Febru- ary 2000 by the Institute for Biological Invasions (see http://inva- sions.bio.utk.edu/invaders/monk.html). Although the initial threat of the Monk Parakeet, that it would become a serious agricultural pest, has not yet materialized (and some would say never will), the species is causing considerable economic damage through nesting on electrical structures. Electrical fires and power outages directly attributable to Monk Parakeets have been reported in Connecticut, Florida, Texas, Il- linois, and New York. The view that the Monk Parakeet should be consid- ered “innocent until proven guilty” (see http://www.monkparakeet.com/ spreyer.htm) may be justified, at least at present, with respect to agricul- tural damage. However, when it comes to the damage the species is caus- ing through disruption of electrical coverage, the proof is in hand that this species is guilty. In summary Monk Parakeets are widely distributed in Florida and abundant in at least two geographical regions, the Central West and Southeast regions. In all areas in Florida where it occurs, the species is experiencing exponential population growth and populations sizes in each area will likely increase. The population in Florida is likely to double within the next eight years, and with this increase, the eco- nomic damage that the species causes through electrical disruption is also likely to double. Literature Cited BUCHER. E. H. 1984. Las aves como plaga en Argentina. Centro de Zoologia Aplicada. Publication No. 9 Cordobe, Argentina, Universidad de Cordoba. BUCHER, E. H., and P. Bedano. 1976. Bird damage problems in Argentina. International Studies on Sparrows 9:3-16, Poland. BULL, J. 1973. Exotic birds in the New York City area. Wilson Bulletin 85:501-505. BUMP, G. 1971. The South American Monk, Quaker, or Gray-headed Parakeet. United States Fish and Wildlife Service, Special Scientific Report — Wildlife No. 136. EBERHARD, J. R. 1998. Breeding biology of the Monk Parakeet. Wilson Bulletin 110:463-473. Freeland, D. B. 1973. Some food preferences and aggressive behavior by Monk Para- keets. Wilson Bulletin 85:332-334. GARRETT, K. L. 1997. Population status and distribution and naturalized parrots in southern California. Western Birds 28:181-195. 12 FLORIDA FIELD NATURALIST LEVER, C. 1987. Naturalized birds of the world. Longman Scientific & Technical, London, England. Neidermyer, W. J. and J. J. Hickey. 1977. The Monk Parakeet in the United States, 1970-1975. American Birds 31:273-278. OWRE, O. T. 1973. A consideration of the exotic avifauna of southeastern Florida. Wilson Bulletin 85:491-500. Simpson, M. B. Jr., and R. C. Ruiz. 1974. Monk Parakeets breeding in Buncombe County, North Carolina. Wilson Bulletin 86:171-172. Spreyer, M. F., and E. H. Bucher 1998. Monk Parakeet ( Myiopsitta monachus ). In The Birds of North America, No. 322 (A. Poole and F. Gill, eds.). The Birds of North Amer- ica, Inc., Philadelphia, PA. SOL, D., D. M. SANTOS, E. Feria, AND J. CLAVELL. 1997. Habitat selection by the Monk Parakeet Myiopsitta monachus during the colonization of a new area. Condor 99:39-46. SOUTH, J. M., AND S. Pruett-Jones. 2000. Patterns of flock size, diet, and vigilance of naturalized Monk Parakeets in Hyde Park, Chicago. Condor 102:848-854, PRUETT-JONES, S., and K. A. Tarvin. 1998. Monk Parakeets in the United States: Popu- lation growth and regional patterns of distribution. Pages 55-58 in Proceedings 18th Vertebrate Pest Conference (R. O. Baker and A. C. Crabb, eds.), University of Califor- nia, Davis. VAN BAEL, S., and S. Pruett-Jones. 1996. Exponential population growth of Monk Par- akeet in the United States. Wilson Bulletin 108:584-588. Pruett- Jones etal, Monk Parakeets in Florida 13 Appendix 1. Geographical regions of Florida, the counties encompassed by these regions, and the specific Christmas Bird Counts in these counties on which Monk Parakeets have been recorded at least once since 1972. Region in Florida Counties in this region Christmas bird counts in these counties on which parakeets have been recorded Northwest North Central Northeast Central West Escambia Santa Rosa Okaloosa Walton Holmes Washington Jackson Calhoun Bay Gulf Liberty Franklin Gadsen Leon Wakulla Jefferson Madison Tarlor Hamilton Suwannee Lafayette Dixie Columbia Gilchrist Union Bradford Alachua Gainesville Levy Baker Nassau Duval Jacksonville Clay St. Johns St. Augustine Putnam Flagler Citrus Crystal River Hernando Pasco New Port Richey Pinellas North Pinellas St. Petersburg Hillsborough Alafia Banks Tampa Manatee Bradenton Gulf Circle, Manatee 14 FLORIDA FIELD NATURALIST Appendix 1. (Continued) Geographical regions of Florida, the counties encom- passed by these regions, and the specific Christmas Bird Counts in these coun- ties on which Monk Parakeets have been recorded at least once since 1972. Christmas bird counts in these counties Region in Florida Counties in this region on which parakeets have been recorded Central West Sarasota DeSoto Sarasota Venice-Englewood Central Marion Sumter Lake Seminole Orange Wekiva River Osceola Kissimmee Valley Polk Hardee Highlands Lakeland Lake Wales Central East Volusia Brevard Okeechobee Indian River St. Lucie Cocoa Southwest Glades Charlotte Peace River Lee Hendry Fort Myers Collier Naples Southeast Martin Jonathon Dickinson State Park Stuart Palm Beach West Palm Beach Broward Ft. Lauderdale Monroe Key Largo Plantation Dade Dade County Royal Palm-Homestead Kendall Area 15 NOTES Florida Field Naturalist 33(1): 15-16, 2005. GREAT EGRETS GLEANING DRAGONFLIES Eric D. Stolen Dynamac Corp., Mail Code: DYN-2, Kennedy Space Center, FL 32899 Although mainly piscivorous, the Great Egret C Ardea alba ) takes a variety of food items including dragonflies (Insecta, Odonata; McCrimmon et al. 2001, Hancock and Kushlan 1984, Palmer 1962). Clark (1980) described gleaning of dragonflies from low salt marsh vegetation by Tricolored Herons ( Egretta tricolor ) near a nesting colony. Gleaning of insects is noted as a foraging behavior of Great Egrets in Kushlan (1978), but I could find no published description of gleaning behavior for the Great Egret. On the morning of 24 March 2003, 1 was measuring foraging rates of wading birds feeding in impounded salt marsh habitat along the Black Point Wildlife Drive on Merritt Island National Wildlife Refuge near Titusville, Florida. Between 10:30 and 12:00 I observed four Great Egrets gleaning dragonflies which were perched on the ends of stems of sand cord grass ( Spartina bakeri) and salt grass ( Distichlis spicata). From my observation point 35 m away, the length of each dragonfly’s body appeared to be less than one-quar- ter of the length of a Great Egret bill, which is typically in the range of 11 cm (Palmer 1962). Two of the Great Egrets that gleaned dragonflies were foraging in a loose mixed- species foraging aggregation (individuals separated by 15-50 m) including four Great Egrets, and one Tricolored Heron. The other two Great Egrets observed eating dragon- flies were foraging solitarily (greater than 100 m to the nearest other wading bird). Dur- ing the time the birds were observed gleaning dragonflies, the birds were moving slowly through the vegetation with the neck extended in an upright posture and body angled away from the ground. The dragonflies were captured with rapid strikes of the head and neck and were swallowed immediately. One of the birds captured six fish and one drag- onfly during the three minutes I observed its foraging behavior; two others captured only dragonflies during the three minutes (one and three dragonflies captured). The last individual observed gleaning dragonflies was not observed long enough to quantify its foraging behavior. Thus, dragonfly gleaning behavior appeared to be a foraging strategy rather than incidental or opportunistic captures during foraging for other prey. The weather was typical of early spring in Florida, with clear skies and air temperature around 22°C with a light wind around 1 1 km/h. On numerous occasions while conducting monthly aerial surveys of wading bird for- aging habitat use during the past six years, I have noticed small groups of Great Egrets foraging in non-flooded Spartina bakeri salt marsh during the winter dry season. These groups typically consist of 2-10 individuals separated by 10-100 body lengths. Individu- als appear to be standing upright and are stationary or moving slowly within the tall (1- 2 m) grass. Accounts of Great Egrets taking various small mammals (Palmer 1962) led me to assume that the birds were foraging for terrestrial vertebrates, but clearly they may have been foraging for insects. Literature Cited CLARK, E. S. 1980. Louisiana Herons gleaning dragonflies. Auk 97:399-400. HANCOCK, J., AND J. A. Kushlan. 1984. The herons handbook. Croom Helm, London. KUSHLAN, J. A. 1978. Feeding ecology of wading birds. Pages 249-297 in Wading Birds (A. Sprunt IV, J. C. Ogden, and S. Winckler, eds). Research Report No. 7, National Au- dubon Society, New York. 16 FLORIDA FIELD NATURALIST McCrimmon, D. A., J. C Ogden, and G. T. Bancroft. 2001. Great Egret {Ardea alba) In The Birds of North America, No, 570 (A. Poole and F. Gill, eds.) The Birds of North America, Inc., Philadelphia. PALMER, R. S. 1962. Handbook of North American birds, Vol. 1. Yale University Press, New Haven, CT. 17 Florida Field Naturalist 33(1):17-19, 2005. FIRST VERIFIABLE RECORDS OF BLUE-WINGED WARBLER AND MAGNOLIA WARBLER WINTERING IN FLORIDA Bill Pranty1, Tom Hinge2, and Mark Berney3 1 Avian Ecology Lab, Archbold Biological Station , 123 Main Drive Venus , Florida 33960 ; E-mail: billpranty@hotmaihcom 221298 Harbour Road , Wheatley , Ontario, NOP 20P, Canada 3 1650 NW 128th Drive , #305, Sunrise, Florida 33323 Publications in this journal have documented first wintering records in Florida of four Neotropical migrants: the Eastern Kingbird ( Tyrannus tyrannus ; Bowman et ah 1995), Black- throated Blue Warbler ( Dendroica caerulescens ; Pranty et ah 2003), Black- throated Green Warbler ( Dendroica virens; Pranty 2000), and Rose-breasted Grosbeak (. Pheucticus ludovicianus; Doyle 2002). In this note, we add the Magnolia Warbler ( Den- droica magnolia) and the Blue-winged Warbler ( Vermivora pinus) to the list of recent, photographically documented winter records. Magnolia Warbler — Just before 11:00 on 10 January 2003, TH observed and video- taped a Magnolia Warbler from the boardwalk at Corkscrew Swamp Sanctuary, Collier County, Florida (Fig. 1). Clearly visible in the videotape are the grayish crown and face with conspicuous narrow white eye-ring; pale greenish mantle with faint black streak- ing; gray wings with two white wing-bars; yellow chin, throat, breast, and belly; yellow flanks with rather bold black streaking ventrally; and white vent and undertail co- verts. The underside of the tail showed the distinctive white basal half and black distal half. Magnolia Warblers breed across central Canada and around the Great Lakes, south- east locally to the southern Appalachian Mountains. Their primary winter range is southern Mexico through Panama, with lesser numbers in the West Indies, and rare re- ports from several southern states (Hall 1994, Dunn and Garrett 1997, AOU 1998). In Florida, Magnolia Warblers were reported during 29 of the past 30 Christmas Bird Count seasons (1973-1974 to 2002-2003; National Audubon Society 2004). Annual counts ranged from 0-17 individuals from as many as eight CBC circles (National Audu- bon Society 2004). Thus, the Magnolia Warbler seems to be a rare but regular winter resident, primarily of the extreme southern peninsula and the Keys. However, appar- ently no winter observation prior to January 2003 can be verified by photograph or spec- imen evidence (Robertson and Woolfenden 1992, Stevenson and Anderson 1994). Prior to our record, a specimen collected by Dennis Paulson at Miami on 5 March 1959 (Stevenson and Anderson 1994) appears to come the closest to document wintering. Blue-winged Warbler— On 10 December 2003, Wally George and Russell MacGregor discovered an adult male Blue-winged Warbler at Topeekeegee Yugnee Park, Broward County, Florida. The bird was among a large mixed wood-warbler flock that included Northern Parula ( Parula americana), Yellow-rumped Warbler ( Dendroica coronata ), Black-throated Green Warbler (. D . virens ), Yellow-throated Warbler CD. dominica), Pine Warbler CD. pinus), Prairie Warbler (D. discolor), Palm Warbler CD. palmarum) and Black-and-white Warbler ( Mniotilta varia). The flock favored live oaks ( Quercus virgini- ana) in the northwest part of the park, and at times associated loosely with feeding Blue Jays ( Cyanocitta cristata). At approximately 09:00 on 25 January 2004, the last date that it was observed, MB videotaped the Blue-winged Warbler as it foraged actively in the canopy of a 7-m tall live oak. Visible in the videotape are the yellow forehead, crown, and face with bold black eye-line; greenish unstreaked mantle; grayish wings with two 18 FLORIDA FIELD NATURALIST Figure 1. Magnolia Warbler at Corkscrew Swamp Sanctuary, Collier County, Florida on 10 January 2003. Note the gray upperparts with the conspicuous eye-ring and wing-bars, the yellow underparts (that appear pale in this photo- graph) with faint black streaking on the flanks, and the distinctive black and white tail pattern. This observation furnishes the first published, verifiable winter record in Florida. Photograph from digital videotape by Tom Hince. bold white wing-bars; yellow chin, throat, breast, and belly; and white vent and under- tail coverts. The bird foraged acrobatically in the foliage, at times hanging upside-down as it examined surfaces of leaves. Blue-winged Warblers breed in extreme southeast Canada and across the northeast United States west to Iowa, Missouri, and Arkansas, and south to north Alabama. The species normally winters in a 900 x 500 km area along the Atlantic Ocean from southern Mexico to Honduras. Wintering birds occur casually in parts of the Caribbean, and from several states, but there are few verifiable records (Gill et al. 2001, AOU 1998, Garrett and Dunn 1997). In Florida, single Blue-winged Warblers were reported on up to three Christmas Bird Counts each during 9 of the past 30 CBC seasons (1973-1974 to 2002 - 2003; National Audubon Society 2004). Thus, it seems to be a very rare and irregular winter resident, primarily of the southern peninsula and the Keys. Specimen records range from 26 March-17 October, and no photograph outside this period is known (Stevenson and Anderson 1994). MB’s videotape furnishes the first verifiable wintering record of Blue-winged Warbler for Florida. A videotape with both warbler observations is catalogued at the Florida. Ornithologi- cal Society Archives (FOSA) at the University of Florida in Gainesville. ACKNOWLEDGMENTS — We thank Wally George for providing his field notes on the Blue-winged Warbler, and Bette Jackson for improving drafts of the manuscript. Notes 19 Literature Cited AOU. 1998. Check-list of North American birds. Seventh edition. American Ornitholo- gists’ Union, Washington, D.C. Bowman, R., P. W. Smith, and J. W. Fitzpatrick. 1995. First winter record of an East- ern Kingbird in Florida. Florida Field Naturalist 23:62-64. Doyle, T. J. 2002. A verifiable winter record of Rose-breasted Grosbeak in Florida. Flor- ida Field Naturalist 30:135-137. Dunn, J. L., AND K. L. Garrett. 1997. A field guide to warblers of North America. Houghton Mifflin, Boston. Gill, F. B., R. A. CANTERBURY, AND J. L. Confer 2001. Blue-winged Warbler ( Vermivora pinus ). In The Birds of North America, No. 584 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Washington, D.C. Hall, G. A. 1994. Magnolia Warbler ( Dendroica magnolia). In The Birds of North Amer- ica, No. 136 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadel- phia, and the American Ornithologists’ Union, Washington, D.C. NAS [National Audubon Society]. 2004. Christmas Bird Count database ). Re- gional compilers are Bruce H. Anderson (2917 Scarlet Road, Winter Park, Florida 32792; ), John H. Boyd III (15291 SW 108th Terrace, Miami, Florida 33196, ) , Linda Cooper (558 Sunshine Boulevard, Haines City, Florida 33844-9540; ), Bob and Lucy Duncan (614 Fair- point Drive, Gulf Breeze, Florida 32561, ), Charlie Ewell (115 Field Observations 27 SW 51st Terrace, Cape Coral, Florida 33991, ), Bev Hansen (6573 Pine Meadows Drive, Spring Hill, Florida 34606; ), Gail Menk (2725 Peachtree Drive, Tallahassee, Florida 32304; no email), David Pow- ell (1407 Storington Avenue, Brandon, Florida 33511; ), and Peggy Powell (2965 Forest Circle, Jacksonville, Florida 32257; ). ■ v i Florida Field Naturalist ISSN 0738-999x PUBLISHED BY THE FLORIDA ORNITHOLOGICAL SOCIETY Editor: JEROME A. JACKSON, Whitaker Center, Arts & Sciences, Florida Gulf Coast Uni- versity, 10501 FGCU Blvd. South, Fort Myers, FL 33965. E-mail: picus@fgcu.edu Associate Editor (for Reviews): REED BOWMAN, Archbold Biological Station, RO. Box 2057, Lake Placid, FL 33852 Associate Editor (for bird distribution): BRUCE ANDERSON, 2917 Scarlet Road, Winter Park, FL 32792. E-mail: scizortail@aol.com Editor of the Ornithological Newsletter: TOM PALMER, 1805 26th Street, N.W., Win- ter Haven, FL 33881. E-mail: tomp47@yahoo.com Editor of Special Publications: JACK HAILMAN, 143 Beacon Lane, Jupiter, FL 33469. E-mail: jhailman@wisc.edu Web Page Editor: KURT Radamaker, 16313 E. Crystal Point Drive, Fountain Hills, AZ 85268. E-mail: webmaster@fosbirds.org INFORMATION FOR CONTRIBUTORS The Florida Field Naturalist is a fully refereed journal emphasizing biological field studies and observations of vertebrates, especially birds, in and near Florida and the nearby West Indies. We welcome submission of original manuscripts containing new information from these areas. We encourage electronic submission of manuscripts. Please consult recent issues of the journal for style, especially noting that manuscripts should: (1) be double-spaced throughout, including tables and figure captions; (2) include the scientific name at the first mention of each species; (3) include capitalized standardized English names for all birds, but lower case for English names of other organisms; (4) include metric units for all measurements; (5) use the form “7 June 2003” for all dates; (6) use the 24-hour clock for all indications of time (e.g., 0800, 1400); (7) use the following abbreviations: s (second), min (minute), h (hour); (8) preferentially use active voice. Submit manuscripts for Florida Field Naturalist to the Editor, Jerome A. Jackson. Monograph-length manuscripts may be submitted for consideration to Glen E. Wool- fenden, Editor of Special Publications. Books and other materials for review should be submitted to: Reed Bowman, Associate Editor for Reviews. Field Observations should be submitted to the Chair of the Field Observations Committee, Bill Pranty. Reports of rare birds in Florida should be submitted to the Managing Secretary of the FOS Records Com- mittee, Reed Bowman. SMITHSONIAN INSTITUTION LIBRARIES 3 9088 01117 5593 Florida Field Naturalist PUBLISHED BY THE FLORIDA ORNITHOLOGICAL SOCIETY Vol. 33, No. 1 February 2005 Pages 1-27 CONTENTS ARTICLE Population Growth of Monk Parakeets in Florida. Stephen Pruett-Jones, James R. Newman, Christian M. Newman, and James R. Lindsay 1-14 NOTES Great Egrets Gleaning Dragonflies Eric D. Stolen 15-16 First Verifiable Records of Blue-winged Warbler and Magnolia Warbler Wintering in Florida Bill Pranty, Tom Hince, and Mark Berney 17-19 FIELD OBSERVATIONS Summer report: June-July 2004 Bill Pranty 20-27