coffosmoM akd ajotoajce or bikd roPuUinoBS m ki?abiak haiiuxs or the uutokhu sesoxsi 4. Sidney England2. Larry D. Foramen3 , and Willi* F. Laudanalayar, Jr.4 1581 4batraet.— avian population verxaoie* including dirnmlty, danalcy, and apaciaa ricntmi in daaart riparian badlcac* aara maimc »« Table l.-Locatlon snd description of 13 ****** d-.rt ripsrian study sic" surveyed >— Novamber 1977 and January 1979. Srudy site Location County Elev. lm) Size Habitat1 . (ha) Structure Habitat Type' Cottonwood Creek: Sam Spring Darwin Falls Chris Wicht Camp Limekiln Spring Brewery Spring Kane Spring Old Woman Springs Salt Creek. Horse Thief Springs Dove Spring Cottonwood Spring Bonanza Spring Hopah Spring Iron Mtn. Pump. Stn. White Hint. Deep Spgs. Valley Argus Mtns. Panamlnt Hens. Panamlnt Htne. Panamlnt Htns. Newberry Mtna. Johnson Valley Salt Spring Hills Kingston Range Hew York. Mens. Granite Htns. Clipper Htns. Turtle Htns. Iron Htns. Mono Inyo S.B.- 1,600 1,700 900 900 1,200 1,400 975 975 160 1,400 1,450 1,300 600 670 290 5.1 1.8 5.6 2.9 3.0 4.6 2.1 36.4 9.8 1.0 0.6 0.2 1.8 0.8 24.8 SO Cottonwood/ willow SO Willow/ locust SO Willow SO s s s SOP so so s so s s SOP Cot tonwood/ willow Willow Willow Hssquite/catdaw Cottonwood/ willow* Heequlte/ealt cedar Cot tonwood/ willow Dwarf aah/hackberry Cot tonwood/ willow Arrowweed/ salt cedar Palm/mesquite Suburbs n woodland* General Land! on Montane Valley Montane Monxane Montane Montane Valley Valley Valley Montane Montane Montane Valley Valley Valley IS - shrub; SO - shrub with tree overstory; SOP - sbrub with tree ovrstory and pond(s). .,3r=z2Gsfi&^^^ asHsfsss. San*- fgffll dossil), aTrowt^c (PliiEri£li«*>. P^ (WasMnRtonl, fillfera). 3s. B. ■ San Bernardino County. ^Consists primarily of man-created habitat with numerous ornamentals. this psper, the continuum of riparian habitats present in the California deserts has been divided into "perennial" and "ephemeral" types. "Perennial riparian habitats typically have water at or near the surface throughout the year (e.g., springs, seeps, streams, etc.). "Ephemeral" riparian habitats occur in washes where surface water typically is available for relatively short periods following storms. Biweekly Surveys Data on avian temporal and habitat use patterns were collected at fifteen locations selected to represent the wide range of "perennial" riparian habitat types and aires found in the California deserts (table 1). Study sites were established at each location; sites rsnged in six* from 0.2 to 36.4 ha. One feature common to all sites was yesr- round presence of surfsce water. Censuses were conducted by systematically walking through each site recording all birds detected; individuals seen in riparian vegetation were recorded separately from individuals in adjacent non-riparian habitat. Two plots were visited per day, one during the three hour period following dawn and one during the three hour period preceding sunset. Length of visits vsried with size of study site and number of birds found. Each study site was visited approxi- mately biweekly during the following periods: Nov- ember 6, 1977 to Jsnusry 28, 1978, April 9, 1978 to June 17, 1978, snd July 16, 1978 to January 3, 1979. Biweekly survey results snd literature review were used to essign each species st each site to one or more of eight seasonal status designations. ■Y.ar^round, summer, and winter residents were species found throughout these time periods. Spring snd fall migrants passed through the sitas relatively quickly. Summer and winter trsnslents indudad species that aoved through the site but, unlike migrants, remained for extended periods on the way to or froa breeding areas (e.g., Great Blue Heron) and spades that occurred widely in the desert but were irregular in riparian habitats (e.g., Bad- tailed Hawk, Roadrunnsr). Vagrants differed froa migrants because they were well outside their normal distributions (e.g.. Brown Thrasher, Rose-breasted Grosbeak). Breeding status in riparian habitat at a study site was considered "conf lrmad" if nesting sctivity was observed or if recently fledged young of species not found in sdjscent desert habitats were sean. Breading wss considered "probable" st a site if the species was known from literature or other study sites to bread in dasert riparian habitats and was presant at the site throughout the breading seaaon. Total number of species obssrved st each site on all visits and total number of breeding species (confirmed plus probable) st each site were plotted against study site size. Sitas with shrubs only, shrubs with tree overstory, snd shrubs with tree overs to ry and ponds were examined separately to determine Che effects of habitat structure cm total number of species end nueber of breeding species. Temporal species richness patterns were ana- lysed by plotting number of species observed per visit et each site against time. If more then one visit occurred at a site In a single biweekly sampling period, the average number of species ems used. Species richness/ time curves for each site were inspected visually and combined into groups with similar pattern*. Characteristic curves for each group were constructed by averaging the total number of specie* observed in each sampling period. Total number of individuals counted on each visit to eecb site were graphed against time for analysis of temporal abundance patterns. If mul- tiple visits occurred et a site in a single sampling period, the average number of individuals was used. Abundance curves were Inspected visually to determine gross abundance patterns. Common bird names are those found in the fifth edition of the A.O.U. Checklist of Birds of North America (1957) as amended by Supplements (1973, 1976). RESULTS Breeding and Winter Bird Surveys Ninety-nine breeding bird censuses and 80 winter bird-population studies were compiled for use in this analysis. Of these 179 surveys, 13 A were in California desert habitats (45 riparian and 89 non-riparian) and 45 were in clsmontene California habitats. Distribution of surveys among habitats and results of the analysis are presented in table 2. Among desert riparian habitats, Cottonwood/ Willow, Willow, and Palo Verde/ Ironwood supported the highest numbers end greatest densities of breeding species. Diversity of breeding species also was highest In these habitats. Cottonwood/ Willow supported approximately two to five times more breeding species than any other desert riparian habitat. The number of visiting species on breeding bird censuses wes higher in all "perennial" desert riparian habitats than in "ephemeral" habitats. Results from winter bird—population studies indi- cated that Cottonwood/ Willow, Palm, and Palo Verde/ Ironwood supported more species then other desert riparian habitats. Winter densities were highest in Willow, Palm, and Palo Verde/ Ironwood. With the exception of visiting species during the breeding season, all values for Palo Verde/ Ironwood, an "ephemeral" desert riparian habitat, fell within the ranges of values for "perennial" habitats. Comparisons between Catclaw and other habitats were complicated by the lack of replicate samples. Comparing data (table 2) between desert ripar- ian and non-riparian habitats showed that density, diversity, and species richness were higher in ell desert riparian habitats during the winter. Breed- ing bird densities were higher In all desert riparian habitats than in non-riparian habitats. The number of breeding species in Desert Woodlend wes comparable to Willow and Palo Verde/ Ironwood and exceeded Palm and Mesquite. Desert Scrub with Overstory supported approximately the seme number of breeding species as Mesquite and was higher than Palm. Breeding species richness was higher in all desert riparian habitats than in Desert Scrub. Only Desert Woodland wes comparable to desert riparian habitats in number of visiting species during the breeding eeeeon. Cismontane riparian habitats generally supported more species es well es more individuals then deeert riparian habitats ( taole 2); diversity values were greater in clsmontene habitats during both seasons. Breeding bird surveys indicated only desert Cottonwood/ Willow supported breeding species numbers comparable to cismontane riparian habitats. Only in deeert Cottonwood/ Willow end Willow were breeding densities similar to cismontane riparian habitats However . the number of visiting species wes greater in nearly all deeert riparian habitats then In clsmontene desert riparian habitats. Clsmontene Cottonwood/ Willow exceeded ell deeert riparian habitats in species richness end density In winter, while Sycamore/ Live Oak was comparable to eeverel deeert riparian habitats. no. • 0 o 1 1 •ne- 1 1 ^»r ck o **' ■ TO- i z m 4 •>- < ♦ o P BO- • • • r • «*r • -•• ♦ ■ Pir m. 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S3 en ■ -e Os S3 US © S3 < C rs pp CM 4- b a • b b b X S3 OC cm m IK le iK«n en o b — . oc ec — - t. ««< o e » • • a «i at ee - — S3 S3 . OS a -pg > vO OS a e • s; 0 b b — ' cm an 01 ss »p en e mm, mm ^m. Ct mm mm < pp fl C CI PS s4 a X 4 e id eo as ee Table 3. Breeding and seasonal status summary for avian species found at 13 "Perennial" desert riparian sites surveyed between November 1977 and January 1979. Number of Species Vagrant No. Breeding Species2 — Overall Baa idem Transient Migrant Sp F Species Richness Pattern3 Study Site Su V Jrl Su W Total C P Cottonwood Creek San Spring Darwin Falls 75 74 75 19 15 13 6 5 14 (l) (2) (3) 10 9 6 V 12 10 32 21 31 30 44 . 40 1 0 4 15 11 10 8 4 9 7 7 1 C A A Chris Vicbt Camp Limekiln Spring Brewery Spring 59 42 41 9 7 6 4 4 6 (0) (0) (0) 5 5 7 9 4 3 23 6 11 29 22 19 3 2 0 6 4 4 5 2 2 1 2 2 A D D Kane Spring Old Woman Springs Salt Creek 43 122 80 8 19 10 5 22 8 (2) (10) (1) 9 11 9 11 20 18 22 48 31 16 75 46 0 4 3 17 7 2 9 3 1 8 4 B A A Horse Thief Springs Dove Spring Cottonwood Spring 82 44 64 15 8 7 8 4 3 (2) (1) (0) 11 9 22 9 5 10 33 17 21 45 15 28 2 1 3 12 5 2 5 0 0 7 5 2 D C D Bonanza Spring Mopah Spring Iron Mtn. Pump. Stn. 46 50 121 7 10 14 5 3 14 (3) (2) (7) 6 7 14 8 12 24 29 20 33 20 18 80 0 0 8 3 7 13 2 4 4 1 3 9 B B D 1-¥r * Tear-round resident species. These numbers are included in both an resident totals. 2g - Confirmed; P - Probable. 3See figure 3 for graphs describing four (A-D) species richness patterns. ir (Su) and winter (V) Biweekly Surveys A grand total of 190 bird specie* were obaerved at all sites on all visits combined. The total number seen at each site ranged from 41 at Brewery Spring to 122 at Old Woman Springs (table 3). Con- siderably more species ware seen at the two large, man-created sites (Old Woman Springs and Iron Mountain Pumping Station) than at any other site. More species were recorded at sites supporting shrub vegetation with tree overstory than at sites with shrub vegetation only (fig. 1). The total number of species observed at sites having shrub vegetation with tree overstory increased with plot else (fig. 1); sites with ponds were included in this regression after excluding species dependent on open water. An analysis using average number of species per visit in place of total number of species produced similar results. The number of confirmed breeding species ranged from zero at Dove and Cottonwood Springs to nine at Old Woman Springs and Darwin Falls (table 3). Total breeding species (confirmed and probable) ranged from two at Cottonwood Spring to 17 at Old Woman Springs. Sites having shrub vegetation with tree overstory generally supported more total breeding species than sites with shrub vegetation only (fig. 2). However, Cottonwood Spring, a site with shrub vegetation and tree overstory, had the lowest breeding species total. This may have been because it bad the smallest area of all sites, consisted of only three Cottonwood trees, and had almost no shrub understory. Mopah Spring was classified as a site with shrub vegetation only but fell within the range of breeding a pedes for sites with tree overstory. The vegetation at this site was predominantly shrubs but also included five palm trees and a number of large Palo Verde. A seasonal status summary for avian species found at each alte la presented in table 3. The largest group of species observed during the bi- weekly surveys was migrants. At 10 of 15 sites, more species were present during fall migration. The number of spring migrant species approximately equalled or exceeded fall migrants at the other five. Tear-round resident species were uncommon at nearly all sites. Only Old Woman Springs and Iron Mountain Pumping Station, both large and diverse man-created habitats, supported a significant proportion of year-round residents relative to the number of summer and winter residents. Summer residents were more common than winter residents at 9 of 15 sites and approximately equal at the remaining six sites. Species richness graphs for each site were classified into one of four general species richness patterns -(table 3, fig. 3) based on shape (l.»., relative position and height of peaks). Five sices were classified as Pattern A, summer and winter lows with nearly equivalent spring and late summer/ fall peaks. Three sites were Pattern B, high spring peak and relatively low late summer/ fall peak. The Pattern C curve, spring high declining steadily to a winter low, included only Cottonwood Creek and Dove Spring. The remaining five sites (Pattern D) were similar to Pattern A except that the spring species richness peak was distinctly lower than the late summer/ fall peek. All patterns with late summer/fall peaks (A, B, & D) reached highest values between mid-August and late October. Species richness Patterns A, B, and D reached spring peaks from mid-April to early May; pattern C reached the spring peak in late May. All patterns reached winter lows from late December to early January and began to increaae in mid-January. Figure 4 displays the results from three apringi selected to represent the range of avian abundance patterns. Abundance was considerably more erratic than species richness becauae abundance was affected more by time of survey, weather conditions, and encounters with large flocks. Highest abundances were reached in summer and fall at 13 of 15 sites (fig. 4A a B) . Nine were highest from mid-July to late August (fig. 4A); six of these had peak abun- dances two to six times greater than any other time of year. The remaining four curves with highest abundances in summer/ fall also had peeks from mid- July to late August, but these were exceeded by peaks from early September to mid-October (fig. 4B) . Kane Spring and Darwin Falls had lows in summer and peak abundances in early December (fig. AC). > c 2»H m 20- u ■ a u- §- P AW I UAv I jw I JUL ^ 1 Aug 1 tf. I 6CT IW6v I 5fec I *w> 1 • ZS 7 21 4 IS ? H XI U 27 10 14 I 22 6 t» 4 saaiisimo date or — weekly imwmuma tcssao Figure 3.— Avian species richness patterns at 15 "perennial" desert riparian study sites sur- veyed between Nov. 1977 and Jan 1979. Type A - Nearly equivalent peaks in spring and lace summer/ fall. Type B - High spring peak and relatively low late summer/ fall peak. Type C - Peak in spring declining steadily to winter low. Type D - low spring peak and relatively high lace aummer/fall peak. Most major abundance peaks were due to large numbers of summer, winter, or year-round resident ground granivores (i.e., California, Gembel's and Mountain Quail, Chukar, Mourning Dove, Horned Lark at Old Woman Springs only, House Sparrow, House Finch, Black-throated Sparrow, Dark-eyed Junco, Brewer's Sparrow at Cottonwood Creek only, White- crowned and Golden- crowned Sparrows). These species accounted for 502 to 90S of the height of aummer/fall abundance peaks (fig. 4A I B) . Most sites showed a small increaae in bird numbers during spring migration. This peak generally was not dominated by realdent ground granivores and was more evident when these species were removed (fig. AA, B, a C). Late fall/ early winter populations varied in the proportion of realdent ground grani- vorea. White—crowned Sparrow, a ground granlvore, was a common winter realdent (fig. AC). However, two foliage lnsectlvorea , Ruby-crowned Kinglet and Yellow-rumped Warbler, frequently were more abundant than realdent ground granivores (fig. AA I B) . DISCUSSION Importance of Desert Riparian Habitats •• V4- W 5 1*1 a _ z O i o- 0 10 20 X 40 PLOT SOI Sal Figure 2.— Total number of breeding species (con- firmed and probable) as a function of plot size and vegetation structure at 15 "peren- nial" desert riparian study sites surveyed between Nov. 1977 and Jan. 1979. Results from study sites with ponds are shown with and without species dependent on open water. The presence of trees or arborescent shrubs in riparian and non-riparian deaert habitats Is an Important variable influencing the breeding avifauna. Although quantitative data on habitat structure are not provided, the pattern of increasing breeding bird diversity, density, and species richness parallels the presence of trees and arborescent shrubs. Among desert riparian habitats, Cottonwood/ Willow, Willow, and Palo Verde/ Ironwood typically have the greatest overacory canopy and thus have a wider availability of percfaea, neat aitea, and foraging aubacrataa. These habitats support more breeding species at higher densities and have a higher breeding species diversity than habitats with leas overs tory (table 2). California fan palms supply a vertical habitat component but do not have the denae canopy provided by trees and arboreacent ahruba. To a leaaer degree, Desert Scrub with overs tory habitats dominated by Joahua tree or ocotlllo also have a vertical component but lack much of the structural complexity that provides foraging and nesting substrata. However, overs tory canopy is Important in non- rlparlan deaert habitats during the breeding aeaaon. Overs tory vegetation decreases from Deaert Woodland to Deaert Scrub with Overscory to Deaert Scrub; 0° I ggj I MAY ; JUN | JJ^ | AUG ■ W I OCT | MOV 1 DEC I JA* ■ -t a ? 314 n ni»ijrKmr i in » i 11 ■WWW— DAT* OF MUU.Y 1MB— KfllOD Figure 4.— Avian abundance patterns at three "per* lnnlal" desert riparian study sites surveyed between Nov. 1977 and Jan. 1979. Upper line on each graph Includes all species; lower excludes selected resident ground granlvores number of breeding species, density, and diversity decline In e similar manner (table 2). During the winter, birds are less dependent on trees and arborescent shrubs for perching and nesting. At this rime, density, diversity, and species richness In riparian and non-riparian habitats are not as well correlated with presence or absence of overstory canopy. Among riparian habitats, Palm had the highest bird densities In winter; species richness values were comparable to Cottonwood/ Willow and exceeded all other desert habitats. This observation may be explained by the feet that California fan palms are restricted to the Colorado Desert which Is warmer in the winter than the Hojave and Greet Basin Deeerts. Among aon- rlparlan habitats, Desert Woodland and Desert Scrub with Overstory supported nearly equal numbers of species , while bird densities in Desert Scrub exceeded Desert Scrub with overstory. Besides the possible presence of tress or arborescent shrubs, water at or near the surface In riparian habitats generally supports denser vege- tation than is found In non-riparian desert areas. By providing more food end cover, this denser vegetation in part supports the higher bird densities found in deeert riparian habitats during breeding and winter pes sons. Surface water also Is an important habitat component influencing bird use, eepecially during the summer months. Smyth and Coulomb* (1971) have shown that granlvorous birds including Cambel's Quail, Mourning Dove, White- winged Dove, Bouse Finch, and Black-throated Sparrow drank regularly at Upper Carrlzo Spring in the Santa Rosa Mountains of southern California. Insectivorous and frugivorous birds were seen drinking less regularly or not at all. Our study found that 13 species of suBmer, winter, or year-round resident ground granlvores accounted for a large majority of birds seen et 15 "perennial" riparian areas (fig. *). Nine of these species were present during the summer, but only two species (Bouse Sparrow and Bouse Finch) nested almost exclusively In riparian vegetation. The rest of these birds presumably were drawn to the spring largely for water during the hot, dry summer months. The Importance of deeert riparian habitats to birds Is not limited to large sites. Relatively small sites are used by many species over the course of a year (fig. 1); this is eepecially true for sites with tree overstory. Small sites with tree overstory generally support more breeding species than sites with shrub vegetation only (fig. 2). However, the number of breeding species does not show the correlation with plot size found for total number of species (fig. 1). Cottonwood Spring, the smallest site with overstory vegetation, almost completely lacked shrub cover under the three cottonwoods and supported fewer breeding species than any other site. However, Horse Thief Springs, the next larger site with overstory, had numerous large cottonwoods end patches of tall dense shrubs. It supported among the highest numbers of breeding birds. Small sices also can support large numbers of Individuals. The Cottonwood Creex sice is approxi- mately five times larger than Horse Thief Springs (cable 1). However, Horse Thief Springs supported numbers of birds comparable Co Coctonuood Creak during spring and winter and considerably more in summer and fall (fig. 4). Local factors including surrounding habicat, geographic location, topograph, and availability of wter in adjacenc areas may affect why some sices support more birds than would be expected considering sire alone. The species composition of bird populations in desert riparian habitats is extremely dynamic. This is reflected in the species richness patterns illustrated in (fig. 3). The typical pattern has peaks in spring and fall with lows in summer and winter. Relatively few species are resident in desert riparian bablcacs; most are either tran- sients, migrants, or vagrants (cable 3). Breeding species typically are present only during the spring when food and water are aosc available and temperatures are relatively mild. However, peak number of individuals frequently is composed of relatively few species (fig. 4). at 9 of 15 sltea. sampled biweekly, peak abundance preceded peak species richness by approximately one month. Explanations for variations in species richness patterns (fig. 3, cable 3) muse be tentative since they are baaed on one year's data collected at biweekly Intervals. Four of five sices with lower species richness in the spring than in the lace summer/fall were in high elevation, montane loca- tions. These sites remain colder and less productive later in Che spring and may be cooler, more moist and support food longer than lower elevation and valley sices in Che late summer/fall. These reasons could explain the observed pattern. However, two high elevation montane sites, Cottonwood Creek and Dove Spring, bad the highest species richness in the spring and declined throughout the year co winter lows. The reasons for this pattern are less obvious, especially since the number of migrant species recorded ac each alee was nearly the same in spring and fall (cable 3). Iron Mountain Pumping Station, a low elevation valley alee, also showed a low spring peak relative co the fall. However, this sice had an extremely high fall peak that may have been due co migrants being attracted co this large, highly visible sice for food and water. Medium co large sites in valleys and low elevation montane sites had nearly equal species richness peaks in lace summer/ fall and spring. Small, low elevation sices situated in valleys had high spring peaks and relatively low fall species richness peaks. Low species richness in the lace summer/ fall may have been due co lack of resources ac very small, hoc sices and lower probability that migrating birds could find these oases. Elevation, size , and visibility appear Co be variables affect- ing the number of bird species using desert riparian habicats during migration. In Che breeding seaaon, more visiting species are found in desert riparian habitats than in clsoontane riparian habitats (cable 2). This pattern probably is due Co Che isolated nature of desert riparian sices and the relative unsuitabillry of adjacent desert bablcacs for many birds. Water, cover, and food usually are more available in bablcacs surrounding clamoncane Chan desert riparian habicats. In che desert, many species found In adjacenc habicats must visit riparian bablcacs In addition, most studies of birds at desert riparian habitats census che entire habitat at Che sice. In clamoncane locations, riparian habicat frequently Is more widely distributed and study plocs usually Include only a piece of the available habicat. Therefore, a greater portion of Che species using riparian bablcac may be found ac desert sites. Management Implications Riparian habicat assoclaced with permanent water is very limited in the desert. However, washes, which are included in che preceding analysis, are more numerous in che desert, As we and others have shown, riparian bablcacs play a vital role in che desert ecosystem by providing water, food, and cover for resident and transient riparian birds, migrating birds, and non- riparian birds, such as quail and doves. Contrasting with che high value and low quantity of riparian habitat in Che desert is Che common and highly intensive use of these areas for non-wildlife purposes. For example, livestock and feral burros often congregate or linger in riparian bablcacs Co take advantage of che ahade, forage, and drinking water. Recreaclonlacs arc accracced co riparian habitats in che desert by che shade and high visual quality. Hashes are used as vehicular thorough- fares because they lack major obstacles. Mining operations frequently use the water in riparian habicats in mining or mineral processing. Riparian habitats are focal points of cultural resources such as historic and Native American sitae. Many of chase uses are in conflict with wildlife or maintenance of the riparian community. Riparian habitats are generally recognized aa vital co desert resident and migrant birds. Knowledge of the importance of riparian bablcacs is vital to land managers as they attempt to resolve use conflicts. Resolution of chese conflicts should consider che breadth of resources which are critical co birds, among these are the availability of surface water and the presence of a tree overacory and dense ground cover. Proper management should be aimed at maintaining or enhancing all of the individual components making up the riparian zone. In addition, the geographic distribution of riparian habitats should be caken Into account when assessing conflicts. Species such as Brown Townee and Lazuli Bunting breed only in riparian habitats in the Mojave and Great Basin deserts. Others including Verdln, abert's Towhee, and Black-called Gnaccaccher are restricted to riparian habitats in che Colorado Desert. An adequate distribution of well-managed riparian habicat is essential espec- ially to the maintenance of species with small distributions in Che California desert*. Results iron biweekly surveys Indicate chat late December sac early January is Che else of i owes i species richness (fig. 3) and bird abundance (fig. A) ac desert riparian sices, Winter bird- populacloa studies conducted primarily In January and February show that aid Co lace winter species richness and abundance is higher. Thus, If lc Is necessary to create s disturbance such as building a fence or installing a management facility, construction during lace December and early January is likely to have s lesser Impact Chan at other times. Of course, activities which Impair habitat will be harmful Co birds regardless of Che season. Buman development and artificial habicacs may be beneficial co Che avifauna. Results of Che biweekly surveys (cable 3) show chat Che two sices with che highest overall species occurrence (Old Woman Springs and Iron Mountain Pumping Station) are co a large degree man-made habicacs. Old Woman Springs (122 species) Includes a reservoir, residences, gardens, and ornamental trees mixed with native vegetation . Iron Mountain Pumping Station (121 spades) Is an entirely artificial sice made up of residential areaa, parka, and a reservoir. These two sices also were especially high in number of year-round resident, fall migrant, and vagrant species. Besides having diverse structure including call trees, buildings, dense shrubery, open wacer, etc., these sices ware exceptionally large (36.4 ha and 24. 8 ha, respec- tively). The low elevation of each site (975 a and 290 m, respectively) made then conducive Co winter residents and winter transients. Thus, If properly mixed with native vegetation, artificial habitats can create structural diversity and provide nest and perch sices which would otherwise not be available. LITER ATUBJE CUED American Ornithologists' Union. 1957. of North American birds. 691 p. Baltimore, Md. Checklist k.0.0. , American Ornithologists'. Union. 1973. Thirty- second supplement co che American Ornitholo- gists' Union checklist of North American birds. Auk 90:411-419. American Ornithologists' Union. 1976. Thlrcy-chlrd supplement Co che American Ornithologists' Union checklist of North American birds. Auk 93:875-879. Johnson, D.H. , M.D. Bryant, and A.E. Miller. 1948. Vertebrate animals of che Providence Mountains area of California. Univ. Calif. Publ. Zool. 48:221-376. Kolb, H. 1965. ecudy. Auc The Audubon winter bird-population . Field Nor.es 19:432-434. Miller, A.E. 1940. Mohave Desert. A transition island in the Condor 42:161-163. Millar, A.H. and B..C. Stebblns. 1964. The Uvea of desert animals In Joshua Tree National Monument. 452 p. Univ. Calif. Press, Berkeley. Shannon, C.E. and W. Weaver. 1963. The mathemat- ical cheory of communication. Univ. 111. Press, Urbana, 111. Smyth, M. and H.N. Coulombs. 1971. Notes on che use of desert springs by birds In California. Condor 73:240-243. There are s few sices in che desert which are unusually rich In bird species. These frequently become focal points for birdwatchers (e.g., Morongo Valley, Furnace Creek Ranch). Such sices are normally large and diverse and support a substantial tree overscory. However, as knowledge of chase sices increases, che Importance of smaller, leas renown riparian sites can become obscured. Large sices have special management significance not only for the rarity of some of the birds found there but also for the high level of public interest in the integrity of che sice. However, this should noc overshadow che importance of che numerous other riparian sices and Che contribution they make co supporting the desert avifauna. ACKNOWLEDGEMENTS We thank the many biologists who conducted and published breeding bird surveys and winter bird- population studies used in this report. Scott ?. Horton developed the biweekly data collection methodology, selected study sites, and conducted Initial surveys. Steven W. Cardiff performed bi- weekly surveys at one sice. Kristin H. Berry supervised che wildlife program of che BLM California Desert Flan Staff. The final and several draft manuscripts were typed by Tracy Cortex. Figures were prepared by Clara Scapp. Sveneson, S. 1970. An International standard for a mapping method in bird census work recom- mended by the International Bird Census Committee. Aud. Field Notes 24:722-726. Van Velzen, W.T. 1972. Breeding-bird census In- structions. Am. Birds 26:1007-1010. Bureau of Land Management Library Bldg. 50, Danver Federal Center Denver, CO 80225 Bureau of Land Management eiafe^O. Denver Federal CenW Denver, CO 80225