STATUS OF NESTING BALD EAGLES IN ARIZONA - University Of New Mexico
j RaptorRes.33(3):218-226 1999 The Raptor ResearchFoundation, Inc. STATUS OF NESTING BALD EAGLES IN ARIZONA DANIELE. DRISCOLL,RONALDE. JACKMAN ANDW. GRAINGERHUNT PredatoryBird Research Group,LongMarine Laboratory,University of California,Santa Cruz, CA 95060 U.S.A. GREGL. BEATTY, JAMEST. DRISCOLLANDRICHARDL. GLINSKI ArizonaGameandFishDepartment, 2221 Greenway Road,Phoenix,AZ 85203 U.S.A THOMAS A. GATZ AND ROBERT I. MESTA 1 U.S.Fish and WildlifeService,2321 WestRoyalPalm Road,Suite103, Phoenix,AZ 85021 U.S.A. ABSTRACT.---A small,isolatedpopulationof Bald Eagles(Haliaeetus leucocephalus) breedsalongthe desert riversof centralArizona.The extent to which it followedthe continentalpattern of declineduring the DDT era cannotbe knownbecauseof the paucityof data before 1970 but, from 1970-93 the number of known breeding pairs increasedfrom two to 34. Some of this growth was an artifact of increased surveys,but much wasreal. During 1987-93, territory occupancyrate was90%, a higher than normal valuefor the species,but nestsuccess(45%) and productivity(0.69 youngper occupiedsite,SE 0.08) were lower than reported for other populationsin the coterminousU.S. Much of the annualvariation in nestingsuccess and productivityresultedfrom heat stressand flooding, factorsthat impactedmany breedingareassimultaneously. We recorded41 breederfatalitiesor replacementsduring262 monitored breeder/years,and additionalfatalitiesand replacementslikelywentunrecorded.If replacementsequated to fatalities, estimated maximum annual breeder survivalwas 0.84 (95% C.I. 0.78-0.88), a lower value than elsewhereestimated.Of 131 monitored pairingsduring the sevenyearsof our research,24 (18%) containedsubadults.This higher than normal rate for Bald Eaglessuggests a paucityof floaters(nonterritorial adults), althoughother factorsmay be involved.Notwithstandingthesesuggestions of reduced demographicpotential,a continuingupwardtrend in the number of territoriesis apparent. K ¾WORDS: Bald Eagle;Haliaeetusleucocephalus; Arizona;nesting; population statur,productivity; breeder turnover;,subadult recruitment. E1 estatusde figuilascalvasanidando en Arizona RESUMEN.--Una pequefiay aisladapoblaci6n de figuilascalvas(Haliaeetusleucocephalus) se reproducea Io largo de los rios del desiertoen el centro de Arizona. Hasta donde estfipoblaci6n sigui6 el patr6n continentalde disminucionpoblacionaldurantela era del DDT, no seha podido comprobardebidoa la falta de informacionexistenteantes de 1970. Entre 1970-93 el nfimero de parejasreproductivas conocidas aument6 de dos a 34. Parte de este aumento furl sobreestimado. Durante 1987-93 la tasa de ocupaci6ndel territorio rue del 90%, un valor mayordel normal para la especie,el rxito de anidaci6n fue del 45% y la productividadde 0.69 juvenilespor sitio ocupado,SE 0.08; Lo cual rue masbajo que Io reportadopara otraspoblacionesde EstadosUnidos.Estasvariacionesfueron atribuidasal impacto del estrescausadosimultfineamentepor el calor y las inundacionesen variossitiosde reproducci6n. Registramos41 fracasosde los reproductoreso remplazosen 262 monitoreosde reproducci6n por afio. Creemosque hubo mas fracasosque no pudieron ser registrados.Si los remplazosfueron igualesa losfracasos, la sobrevivencia anualde reproducci6nfue de 0.84 (95% C.I. 0.78-0.88), un valor masbajode lo estimadoen otroslugares.De las131 parejasmonitoreadasdurantelos7 aftosde nuestra investigaci6n,24 (18%) contenian individuossubadultos.Estascifrasson mas altas de lo normal para las figuilascalvas.Lo anterior pudo ser ocasionadopor el estancamientode los individuos"floaters" (adultossin territorio), aunque otrosfactorespudieron ser los causantesde estasituaci6n.A pesarde estoy sin subestimarestasituaci6nde reducidopotencialproductivo,seobservauna tendenciacreciente de territorios ocupados. [Traducci6n de Crsar Mfirquez] Present address: U.S. Fish and Wildlife Service, 2493 Portola Road, Suite B, Ventura, CA 93003 U.S.A. 218
SEPTEMBER 1999 STATUS OF BALD EAGLES IN ARIZONA numbers of eagles is unknown, although it was clear that many territorieshad been newly established. Others may have been long occupiedand simply found by greater search efforts and more extensivesurveys,an uncertainty that has affected studiesof other populations (Sprunt et al. 1973, Henny and Anthony 1989, Frenzel 1991). Newly lagstaff discovered 219 sites we examined often contained nu- '-] . ' . ßHolbrook merousold nests,but whether thesewere recently occupied or were remnants of many years past could not be determined Phoenixß '" :' .] / since stick nests on cliffs in Arizona may persistfor many decades. Also uncertain, becauseof the paucity of data before 1972, is the extent to which the Arizona 100 km populationfollowedthe continentalpattern of decline during the DDT era. DDT wasapplied extensivelyto cotton and vegetablecropsin Arizona and adjacent regions, and the highest DDE levels recordedduring the 1967-79NationalStarlingMonitoring Program were from nearby Maricopa, Ari- ßTucson Figure 1. The distribution of breeding Bald Eagles in Arizona. zona and Chaves, New Mexico (Hunt et al. 1986). Prey fish probably contained very little DDE because relatively few farms existed within the drainagesoccupied by breeding eagles;however, migratoryand nomadicwaterbirdswere likely con- Arizona supports a nesting population of Bald Eagles(Haliaeetusleucocephalus) primarily along the Salt and Verde Rivers in the central part of the state (Fig. 1). This small population is somewhat isolatedfrom other centersof breedingactivityand occupieshabitat drier, warmer, and lessvegetated than is typical for the species. Large trees are scarcealong the desert rivers and many pairs use cliff nests.The population has been classifiedas threatened by the U.S. Fish and Wildlife Service (USFWS 1995), and there is concern that the rapidly increasinghuman population in Arizona may impact its numbers. Herein, we summarizedata on occupancyand productivity,and discussfactorsaffecting survival and recruitment. Drawing upon historicalrecordsand reports,and upon field data obtained during 1987-93, we examine the evidence for populationself-sustainability. taminated. There is evidencefor the existenceof a nesting populationof Bald Eaglesin Arizonaprior to 1970. Early sightingsof individual eagleswere reported by Coues (1866), Henshaw (1875), Willard (1916) and Hargrave (1939). Mearns (1890) describedthe first breeding record, a tree nest near Stoneman's Lake on the Mogollon Plateau. Bent (1937) reported breeding pairs at Fort Whipple and the Salt River Bird Reservation,an area flooded by Roosevelt Reservoirin 1911. According to Jenksand Stevenson (1937), Bald Eagles bred in the White Mountains records HISTORY OF OCCURRENCE and were resident in central eastern Ar- izona, primarily in the Transition and Upper Sonoran zones. Cited records of two nestsin saguaro cacti(Cereus giganteus)on the lower Verde River in 1937and a nestingpair on the Little ColoradoRiver in 1951. Phillips et al. (1964) reported nesting from the 1930-60s on the Salt and Verde rivers, including pairs breeding during 1930-36 When the USFWS began monitoring nesting near SaguaroReservoir (constructedduring 1928Bald Eaglesin Arizona in 1970,only two occupied 30), since the early 1940s near Bartlett Reservoir territories were known, both on the Verde River (completed in 1939), and in the free-flowing Salt (Rubink and Podhorny 1976). From 1970-93, the River Canyon in 1935, 1944, and 1949. C. Mcnumber of known territories increased to 34. To Collough (field notes) observed nesting on the what extent this increase resulted from greater Torito Arm of Roosevelt Reservoir from 1951-55.
220 Dmscox.x. ET . VOL. 33, NO. 3 USGS tarsalbandsand similarly-sized, color-anodizedaluminum visual identification (VID) bands engraved with varioussymbols. the mouth of the Verde River in 1968. L. Forbis We recorded standardbody measurementsof breeding (U.S. ForestService,unpublishedinterviewwith E eaglesasdescribedby Bortolotti (1984a, 1984b) and GarThompson1979) noted three nestson the upper celon et al. (1985), including hallux length, culmen Verde River occupied during the early- to mid- length, beak depth, tarsuswidth, length of tail and eighth primary, and weight. A cloth tape was used to measure 1960s.G. Gibbons (pers. comm.) observednesting wing chord length acrossthe dorsum.We comparedthe at CanyonReservoiron the Salt Riverin the 1950s means for each measurement (t-test) from Arizona (10 and 1960s. males, 4 females), northern California (9 males, 11 females) and the Greater YellowstoneEcosystemin WyoSTUDY AREA ming and Montana (12 malesand 6 females;A. Harmata In Arizona, Bald Eaglesbreed mainly in open, desert unpubl. data). Rubink and Podborny(1976) describeda nest on the upper Verde Riverin the 1960sand a pair near landscapes of the Upper and Lower SonoranLife-Zones (Lowe 1964) at elevationsrangingfrom 329-1719 m. Annual precipitationaveragesfrom 39 cm at higher eleva- RESULTS AND DISCUSSION Reproduction.Over the 7-year period of our uons to 25 cm in desert scrub habitats,where temperatures may reach 50øC. Livestockgrazing, particularly study (1987-93), the occupancyrate in centralArduring the closeof the 19th century,createdconditions izonawas90% (183 of 204 known territory/years) leading to extreme lossof soilsand vegetation,including ascomparedto a mean of 71% for numerousother formerly extensiveriparian forests(Hayden 1965, Hastings 1959, Hastingsand Turner 1965, Davis1982). The resulting need for flood control and water storage prompted the constructionof damsin the early 1900s (Hayden1965). Considerable humanrecreationalactivity occurs along the water courses.Some Bald Eagle territories are easilyaccessible,while others are in remote canyons. Reservoirs and riverinc sections contain both native and introduced fishes.Speciesmost commonlyeaten by Bald Eaglesare catfish (Ictaluruspunctatusand Pylodictis ohvaris),sucker (Cat0st0mus clarkiand C. insignis),common carp (Cyprinuscarpio),and perciforms(Pomoxis nigromaculatus, Moronemississippiensis and Micropterus salmondes)(Haywoodand Ohmart 1986, Grubb 1995, Hunt et al. 1992). Of thoselisted,only the suckersare native to Arizona. In winter, waterfowl are important prey of the breeding population, especiallyat reservoirs. METHODS During 1987-93, we collected occupancyand reproductive data both on foot and by monthly helicopter fl ghts throughout the breeding season(January-June). Data recorded during the flights included the number of adults seen, location of new nests,number of nestlings and their approximateage.At many territories,nestwardens of the Arizona Bald Eagle Nest Watch Program (ABENWP) reported the exactdatesof egglaying,hatching and fledging, and recorded observationsof disturbance and fatalities (Forbis et al. 1985). Status terminology followed Postupalsky(1974). Using techniques describedin Hunt et al. (1992) andJackmanet al. (1993, 1994), we radiotagged 15 juveniles, eight subadultsand North American populations reviewedby Stalmaster (1987). Nest successin Arizona was45%, mean brood size 1.5 young and productivity0.69 young (SE - 0.08) per occupied site (Table 1). Except for brood size, these figures are the lowestreported in a sample of nine other populations in the coterminousU.S. for roughly the sameperiod (Table 2). On average,only 11.9 (range 9-16) of the 2330 pairswereproductivein anyone year (Table 1). For the mostpart, the low productivityresultednot from failure to lay eggs but from lossof eggsor young.These resultswere surprisingin viewof the nestprotectionand frequent enhancementof nestling survivalby the ABENWP,activesince 1978. Young blown from nestsby high winds and those threatenedby impending inundation or the lossof a parent were replacedor fosteredinto other nests (Grubb 1984). Egg Mortality.During our 7-yrstudy,73 (31%) of 237 known eggs perished or were infertile, a figure comparableto the 25% reported by Stalmaster (1987) for other North American populations. Of 24 eggs (in 13 clutches)for which we knew the mortalitycause,11 involvedhuman disturbance, four (two clutches) were lost to nest in- undation by filling reservoirs,six (three clutches) 12 breeders at 10 territories. We monitored survival of relationshipwhere the male assistradio-taggedeaglesby airplane.Breederreplacementwas to a polygynous determined on the basis of identifying characteristics ed only his primary mate, two when a female (e.g., bands on right versusleft tarsi, adults preceding ceasedincubatingbecauseof apparent physiologisubadults,and known deathsof unmarked pair members [Gould and Fuller 1995]). Except in caseswhere our acuvitiesmight havejeopardized nestlingsurvival,we en- cal distress, and one involving an exceptionally small egg. Sevenaddled eggswe collected during 1986-89 tered all occupiednestsduring 1987-93 and banded all eagletssurvivingto 6 wk of age (N 119) with standard averaged5.5 ppm DDE (range -- 2.3-9.5) and 2.2
SEPTEMBER1999 STATUS OF BALD EAGLESIN ARIZONA 221 Table 1. Knownproductivity at Arizonabaldeaglebreedingareasduring 1970-93.1TerminologyfollowsPostupalsky (1974). KNOWN MEAN BREEDING OCCUPIED YOUNG % NEST BROOD AREAS NESTS NESTS FLEDGED SUCCESS SIZE PRODUCTIVITY 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 2 3 4 6 8 9 9 9 11 12 2 3 3 5 5 7 5 7 10 10 2 3 0 5 3 4 4 3 6 4 3 4 0 7 6 5 7 6 9 6 100.0 100.0 0.0 100.0 60.0 57.0 80.0 42.9 60.0 40.0 1.5 1.3 0.0 1.4 2.0 1.2 1.7 2.0 1.5 1.5 1.50 1.33 0.00 1.40 1.20 0.71 1.40 0.86 0.90 0.60 1980 1981 1982 12 9 3 5 33.3 1.7 0.56 13 14 10 13 8 8 16 14 80.0 61.5 2.0 1.7 1.60 1.07 1983 1984 15 18 13 17 7 8 13 15 53.8 47.1 1.9 1.9 1.00 0.88 1985 20 19 13 22 68.4 1.7 1.16 1986 1987 21 26 16 24 12 11 17 20 75.0 45.8 1.4 1.9 1988 1989 27 28 23 25 15 9 24 13 65.2 36.0 1.6 1.4 1.06 0.83 1.04 0.52 1990 1991 28 29 26 26 9 13 14 20 34.6 50.0 1.6 1.5 0.54 0.77 1992 32 30 10 14 33.3 1.4 0.47 1993 34 29 16 22 55.2 1.4 0.76 YEAR SUCCESSFUL Data from 1970through1985from Rubinkand Podborny(1976), Hildebrandtand Ohmart (1978), Hildebrandt(1981), Ohmart and Sell (1980), Haywood and Ohmart (1980, 1981, 1982, 1983), Grubb et al. (1983), Grubb (1984, 1986). Table 2. Productivitycomparisonof bald eagle populationswithin the coterminous United Statesover a similar period. OCCUPIED REGION PERCENT MEAN NEST BROOD PERIOD NESTS Florida 1988 399 69 ? 1.1 Wood Louisiana 1988 36 67 ? 1.1 Wood et al. 1990 Texas, Southeast 1981-90 193 64 1.5 0.98 Mabie et al. 1994 Colorado Wyoming 1981-89 85 63 1.9 1.21 Kralovec et al. 1992 1988 50 82 ? 1.4 Wood et al. 1990 84 77 ? 1.4 Wood et al. 1990 1448 97 70 79 1.7 ? 1.21 1.4 Buehler et al. 1991 Wood et al. 1990 58 45 1.6 1.5 0.90 0.69 Jackman(unpubl.data) (thisstudy) South Carolina Virginia ChesapeakeBay Maryland California Arizona 1988 1981-90 1988 1987-93 1987-93 69 183 SUCCESSES SIZE PRODUCTIVITY SOURCE et al. 1990
222 DP scoLL ET . ppm PCBs (range 1.2-3.9) wet weight (Jenkins et al. 1994). No DDE effect on productivitywas apparent in the breeding areas from which eggs were obtained, although Wiemeyer et al. (1984) reported that DDE levelsof this magnitudewere associated with a 50% depressionof productivityin VOL. 33, NO. 3 breeders from 1951-93. Two were killed by other Bald Eagles, one by a Golden Eagle (Aquila chrysaetos), one by a PeregrineFalcon (Falcoperegrinus), five were shot, one died of impact injuries, and three died of unknown causes. We infer an addi- tional 46 breeder fatalities (24 males, 21 females, a 14-statestudyduring 1969-79.A mean thinning 1 unknown) from replacement of pair members rate of 6.9% for 156 eggshellfragments(including (Gould and Fuller 1995). No marked breeder was membrane) waswell below the 10% level associat- seen after its replacement. The two oldest known ed with reduced productivityin other bald eagle breeders were 14 years old in 1993, with site tenpopulations(Wiemeyeret al. 1984, Nisbet 1989). ures of 11 and 10 years. Consideringonlythe 1987-93 period,we recorded 41 fatalities or replacementsduring 262 monifrom 1977-85. tored breeder/years.If replacementsequate to faNestlingFatalities.During our study,37 (22.6%) talities,the (maximum) point estimateof breeder nestlings died among the 164 known to have survival becomes 0.84 (95% C.I. 0.78-0.88) hatched, as comparedwith 15% reported by Stal- (Trent and Rongstad1974), a figure somewhatlowmaster(1987) for other populations.However,few er than that reported in three other studies(i.e., studieswere likely to havemonitored nestsasclose- 0.88 by Bowman et al. (1995) in Alaska, 0.93 by ly as those in Arizona where many were watched Hodgeset al. (1987) in Alaskaand 0.93 by Gerrard continuouslythroughout the breeding season.We et al. (1992) in Canada. Because some deaths and recorded an additional six fatalities around the replacementsin Arizona likely went undetected, time of first flights from the nest.Weather-related our estimate was doubtlessbiased toward higher factors were the apparent cause of death in 23 survival,as may have been the casewith the esti- These findings are similar to those reported by Grubb et al. (1990) for Bald Eagles in Arizona (53%) of the 43 total cases.In 1988 and 1989, heat mate of Gerrard et al. (1992). The estimates for stressappeared to be the primary agent in the death of 11 young (seeNelson 1969, Beechamand Kochert 1975, Hayesand Gessaman1980). During 1992 and 1993, heavyrains and flood conditions were the apparent cause of 11 fatalities and the Alaskawere basedon samplesof radio-taggedeagles. Breeding Eagles in Subadult Plumage. Bald eagles normally defer first breeding until at least 58 yearsof age (Hansen and Hodges 1985, Buehler destruction et al. 1991, Gerrard et al. 1992, Bowman et al. of 10 nests. Additional causes of death 1995). Healthy raptor populationstypicallycontain many floatersunable to obtain breeding territories 1986), falling from (or being blown out of) nests because suitable habitat is saturated by breeding included Mexican chicken bug (Haematosiphon inodorus)infestations (N 5) (see also Grubb et al. (N 4), human disturbance before self-thermo- pairs (Newton 1979). However,during the seven regulation (N -- 3), Great Horned Owl (Bubovir- years of our study, the Arizona population apgnnianus)predation (N 2), entanglement in peared to contain relatively few floaters, as evimonofilament fishing line (N 2), and bacterial denced by a high incidenceof breeding eaglesdisinfections (N 2). playingsubadult(nondefinitive)characteristics (24 Heavy rains not only directly caused nestling of 131 monitored pairings,18.3%). This and the mortality, they also transformed rivers and creeks incidence of replacements by young eagles into muddy torrents, reducing fish availability (-- 44%) were far higher than reported elsewhere (Grubb 1995). Only two of 14 breeding pairs on (Herrick 1924, Bent 1937, Gerrard et al. 1978, free-flowingriver reachessuccessfully raisedyoung Sherrod et al. 1976, Stalmaster 1987, Mabie et al. in 1992, a flood year. We examined prey remains 1994, Anthony et al. 1994). In a long-term study from the two successfulnests and fouffd signifi- involving thousandsof Bald Eagle pairings in Sascantly higher mammalian numerical composition katchewan, Gerrard et al. (1983) noted only two (X2 18.4, df -- 1, P 0.005 and X2 -- 7.4, df subadultspaired with full-adults and neither pair 1, P 0.01) compared to remains we collected laid eggs.Among hundreds of pairs at Chesapeake during 1986-90 from these same nests. Bay, Buehler et al. (1991) observed no subadults Breeder Fatalities and Turnover. Thirteen fataland Hansen and Hodges (1985) remarked that ities were documented for Arizona Bald Eagle subadults were not known to breed in southeastern
SF.PTF.M} F.R 1999 ST TUS OF BALD E GLF.StN AmZON Alaska. Swenson et al. (1986) noted five subadults paired with full-adultsin 11 yearsof data for 4050 pairs in the Greater YellowstoneEcosystem (1972-82); only two such pairs repaired a nest or laid eggsand none reproduced. Some of the pairings and replacementsin Arizona by eaglesin subadultplumagemay reflect a possiblyatypical delay in the acquisitionof full adult (definitive) plumage. J. Driscoll noted that six of 23 eaglesof known age (5 females, 1 male) retained eye-stripesat greater than five years of age, and two of these still displayedeye-stripesat seven years of age. McCollough (1986) reported that two of 13 individuals in Maine retained eyestripe remnants at six to eight years. Pairswith membersdisplayingsubadultplumage in Arizona were more productivethan thosein other studies.Among the 40 pairings containing sub- adultsat 35 occupiednestssince1970, 16 (46%) successfully fledged young, three (9%) hatched youngthat died in the nest,four (11%) laid eggs that did not hatch, and the remaining 12 (34%) apparently did not lay eggs.Of the five pairs with both members in subadult plumage, three apparently did not lay eggsand two hatched two young each. Although significantlymore full-adult pairs laid eggsthan did subadultor mixed pairs (X2 8.0, df 1, P 0.005), we found no significant difference in nest successor productivity. Relationship to Other Populations. There is some evidence that the Arizona Bald Eagle population may be augmented by immigration from other regions.We were able to read the bands of 14 of 29 banded breedersduring 1987-93. All 14 had been banded as nestlingsin Arizona. Six of the unidentified birds were banded on the left tar- sus, but according to banding records, only four Arizona nestlingshad been so banded. Thus, at least two breeders may have originated from outside Arizona. In 1994, an eagle banded as a nestling by Mabie et al. (1994) in southeastTexas (1410 km away) bred at a high altitude reservoir (2438 m) in the pine-forestedmountains of eastern Arizona near the New Mexico border. Arizona adults were, on average,smaller in all morphological characteristics than those from Alaska, California, or the Greater Yellowstone re- gion, a finding that supportsan affinity of the Arizona population with those in the southeastern U.S. as proposed by Amadon (1983), Stalmaster (1987), and Palmer (1988). Arizona maleswere significantlysmallerin 13 of 16 measurements(Table 223 3) and females in eight of 16 comparisons,a difference probably arisingfrom the small number of females sampled. Morphological measurementsof two adults from the Rio Yaqui, Sonora, Mexico did not differ from those in Arizona. These resultssuggestedthat the Bald Eagle population in the southwest either rebounded from a depleted population or derived from immigration from the southeasternU.S., or both. If gene flow into Arizona from north or west (where eaglesare larger) had recently occurred, it should at leastbe reflected in the overall variance of mensural char- acters, assuming that the environmental component of such variation is weak compared with the genetic component. We examined this hypothesis by comparing coefficientsof variation for the various characters we measured in the four populations, but found no suggestionof greater variance within the Arizona sample. SUMMARY OF STATUS Despite the uncertainty of determining whether newly discoveredpairs equate to newly occupied territories, the weight of evidence indicates a continuing upward trend in the number of Bald Eagle pairsin Arizonasince1970.This trend is occurring with little direct evidence of augmentation by immigrants and despite relatively low estimates of productivityand breeder survival.The substantial incidence of pairs containing membersin subadult plumage suggestsa deficient age structure in the floating segmentand thus a relativelysmallrecruitment buffer (Hunt 1998). A paucity of floaters may, in part, result from continued population expansion (i.e., eaglesthat would otherwise become floaters are founding new territories). However,we do not discount the role of low vital rates (e.g., breeder survival) in retarding floater accrual. We therefore recommend monitoring of breeding sites and continuation of population-wide VID banding. Becauseof the proven benefit of the ABENWP in enhancing reproduction, we recommend its continuance at sites where human distur- bance is considered significant. ACKNOWLEDGMENTS Funding for this studyand its publicationwasprovided by the U.S. Bureau of Reclamation (USBR) with assistance in some yearsfrom the Arizona Game and Fish Department.We thank H. Messingand D. Busch(USBR) for help with the project. The USBR and Salt River Project (SRP) providedhelicoptersand pilotsB. Barnesand D. Blakelyfor surveyflights, nesdingemergencies,and
224 DP.iSCOI I Eq: I . VoL. 33, No. 3 access to remote breeding areas for nest climbs. We thank M. Greenburg and T. Noble (SRP) and C. Thelander (BioSystemsAnalysis, Inc., BSAI) and numerous BSAI employeesfor their assistance during our study.We acknowledge the work of D. Rubink (USFWS), R. Ohmart, T. Hildebrandt, D. Haywood and R. Sell (Arizona State University), T. Grubb, W. Ealde and L. Forbis (USFS), and the hundreds of ABENWP personnel who have watched over Arizona'snesting eaglessince 1978. We acknowledgeD. Bland, L. Kiff, and R. Risebroughfor work concerning eggshell thinning and contaminants. We thank J. Linthicum, T. Hunt, and two anonymousreviewersfor valuablecommentson the manuscript. LITERATURE CITED AMADON,, D. 1983. The Bald Eagle and its relatives.Pages 1-4 in D.M. Bird, N.R. Seymour and J.M. Gerrard [EDS.], Biologyand managementof Bald Eaglesand Ospreys.Harpell Press,MacDonald Raptor Research Center of McGill Univ., Montreal, Quebec, Canada ANTHONY, R.G, R.W. FRENZEL, F.B. Is cs ? SI) M.G GAaRETT.1994. Probable causesof nesting failures in Oregon's Bald Eagle population. Wildl. Soc.Bull. 22' 576-582. B CHAM,JJ. XNI)M.N. KOCH T. 1975.Breedingbiology of the Golden Eagle in southwestern Idaho. Wilson Bull. 87:506-513. BENT, A.C. 1937. Life histories of North American birds of prey. Part 1. SmithsonianInstitution, U.S. Nat. Mus Bull. 167. U.S. GovernmentPrintingOffice,Washington, DC U.S.A. BORTOLOTTI,G.R. 1984a. Sexual size dimorphism and age-relatedsizevariation in Bald Eagles.J. Wildl.Manage.48:72-81. ß 1984b. Criteria for determining age and sex of nestlingBald Eagles.J. FieldOrnithol.55:467-480. BOWMAN, T.D., P.E SCHEMPF ? NI)J.A.BERNATOWICZ. 1995 Bald Eagle survivaland population dynamicsin Alaska after the Exxon Valdez oil spill.J. Wildl. Manage 59:317-324. BUEHI E ,D.A., J.D. FRASEr, J.K.D. SEEGEr,G.D. THEmes AND M.A. B'mD. 1991. Survival rates and population dynamicsof Bald Eagleson ChesapeakeBay.J. Wildl. Manage.55:608-613. Cotms, E. 1866. List of the birds of Fort Whipple, Arizona. Proc. Acad. Nat. Sci. Phila. 18:39-100ß DAVIS, G.P. 1982. Man and wildlife in Arizona: the Amer- ican exploration period, 1824-65. Arizona Game and Fish Dept., Phoenix, AZ U.S.A. FORBIS,L.A., T.G. G u /u I) W.D. ZEEI)YK.1985. "Eagle Beagles": a volunteer Bald Eagle nest watcher program on Arizona national forests.Pages 246-254 in J.M. Gerrard and T.N. Ingram [EDS.],The Bald Eagle in Canada,Proc. Bald EaglesDays,1983.White Horse PlainsPublishers,Headingly,Manitoba, Canadaß FRENZEL, L.D. 1991. Bald Eagle and OspreyßPages23-31 in Proceedings of the Midwest raptor management
SEPTEMBER 1999 STATUS OF BALD EAGLES IN ARIZONA symposiumand workshopßNatl. Wildl. Fed., Washington, DC UßSßA. GARCELON, D.K., M.S. MARTELL, P.T. REDIG AND L.C. BUOEN.1985. Morphometric, karyotypicand laparoscopictechniquesfor determining sex in Bald Eagles. J. Wildl. Manage.49:595-599. 225 HAYWOOD,D.D. AND R.D. OHMART.1980. Study of the breeding biology of Bald Eagles in Arizona: statusreport. USFWS, Phoenix, AZ UßSßAß --AND --. 1981. Study of the breeding biology of Bald Eaglesin Arizona:1979-80. USFWS,Phoenix, AZ U.S.A. --AND --. 1982. Study of the breeding biology of Bald Eaglesin Arizona: 1981ßUSFWS, Phoenix, AZ RARDANDW.J. MAHER.1978. Migratorymovements U.S.A. and plumage of subadult SaskatchewanBald Eagles. Can. Field-Nat. 92:375-382. -AND--'. 1983. Study of the breeding biology , P.N. GERHARD, G.R. BORTOLOTTI AND D.W.A. of Bald Eaglesin Arizona: 1982. USFWS, Phoenix, AZ UßS.A. WHITFIELD.1983. A 14-yearstudyof Bald Eaglereproductionon BesnardLake, Saskatchewan. Pages47-57 --AND --. 1986ßUtilization of benthic-feeding in D.M. Bird, N.R. Seymour andJ.M. Gerrard [EDS.], fish by inland breeding Bald EaglesßCondor88:35-42. Biologyand managementof Bald Eaglesand Ospreys. HENNY,CJ. ANDR.G. ANTHONY.1989. Bald Eagle and OsHarpell Press,MacDonald Raptor ResearchCenter of prey. Pages66-82 in Proceedingsof the western rapMcgill Univ., Montreal, Quebec, Canada. tor management symposium and workshop. Natl , P.N. GERHARD, G.R. BORTOLOTTI AND E.H. DZUS. Wildl. Fed., Washington DC U.S.Aß 1992.A 24-yearstudyof Bald Eagleson BesnardLake, HENSHAW,H.W. 1875. Annotated list of the birds of AriSaskatchewan. J. RaptorRes.26:159-166. zona. In U.S. Geographicand GeologicalSurveywest GOULD,W.R. AND M.R. FULLER.1995. Survivaland popof the One-hundredthMeridian, by Lieut. GeorgeM ulation sizeestimationin raptor studies:a comparison Wheeler. U.S. Government Rep., Washington, DC U.S.A. of two methods.J. RaptorRes.29:256-264. GRUBB,T.G. 1984. 1984 Arizona Bald Eagle research re- HERRICK,F.A. 1924. Nestsand nestinghabits of the American eagle. Auk 41:213-231. port. USFS, Rocky Mountain Forest and Range Experiment Station, Tempe, AZ U.S.A. HILDEBRANDT, T.D. 1981. The ecologyof breeding south1986. Arizona Bald Eagle research 1983-85. ern Bald Eaglesin Arizona, 1977 and 1978. M.S. thesis,Arizona State Univ., Tempe, AZ U.S.A. USFS,RockyMountain Forestand RangeExperiment Station, Tempe, AZ U.S.A. --AND R.D. OHMART.1978. Arizona breeding Bald ß1995. Food habits of Bald Eaglesbreeding in the Eagleinvestigations: 1977 annualreport. USFS,PhoeGERRARD, J.M., D.W.A. WHITFIELD,P. GERRARD, P.N. GER- Arizona desert. Wilson Bull. 107:258-274. , W. EAKLEANDJ.L. GANEY.1983. 1983 Arizona Bald Eagle research.USFS, R
population of Bald Eagles in Arizona prior to 1970. Early sightings of individual eagles were reported by Coues (1866), Henshaw (1875), Willard (1916) and Hargrave (1939). Mearns (1890) described the first breeding record, a tree nest near Stoneman's Lake on the Mogollon Plateau. Bent (1937) re- ported breeding pairs at Fort Whipple and the Salt
Although, eagles are found throughout the world, the bald eagle can only be found in North America. Both the golden eagle and the bald eagle can be seen in Pennsylvania. The golden eagle migrates through Pennsylvania and may stay through the winter. The bald eagle is a resident bird and now nests throughout the state. 2.
range of the Sonoran Desert bald eagle population, which remains protected as a threatened species. The Bald and Golden Eagle Protection Act (Eagle Act) remains as the primary law protecting bald eagles in other parts of its range and the golden eagle (Aquila chrysaetos). The Eagle Act authorizes the Secretary to permit take of eagles
Bald and Golden eagles are compara- ble in size; females and more northern individuals of both species are larger. The Bald Eagle has a larger head and bill and longer neck than does the Golden. The Bald Eagle's wings appear slimmer in flight with the trailing edge more near- ly parallel to the leading edge than the Golden Eagle's.
season, eagles usually carry prey to a perch or deliver it to the nest to feed their young. Adults feed chicks by tearing off pieces of food and holding the pieces to the beaks of the eaglets. The nestlings begin to feed themselves at about seven weeks of age. Habitat Like all wildlife, bald eagles require four habitat
3.3.1 Nesting Survey 10 3.3.1.1 2005 Loggerhead Nesting Summary 10 3.3.1.2 Spatial Distribution of Loggerhead Turtle Nests 11 3.3.1.3 long-term Trends in Loggerhead Turtle Nesting 12 3.3.1.4 Seasonal Patterns of Loggerhead Turtle Nesting 14 '3.3.1.5 Predation on Loggerhead Turtle Nests 14 3.3.1.6 2005 Green and Leatherback Nesting Survey 15
2. The Bald and Golden Eagle Protection Act The Bald and Golden Eagle Protection Act (BGEPA) is the primary law protecting eagles. BGEPA prohibits “take” of eagles without a permit (16 USC 668‐668c). BGEPA defines “take” to include “pursue, shoot at, poison, wound, kill, capt
National Park Service, Glacier National Park, West Glaci MT 59936 U.S.A. AgsTv, CT.- During 1985-95, we documented fledging, migration, and subsequent locations of juvenile bald eagles (Haliaeetus leucocephalus) from Glacier National Park (GNP),
Use the English phonemic alphabet page, which you find at the beginning of good dictionaries, as a guide to pronouncing new words. Effective English Learning ELTC self-study materials Tony Lynch and Kenneth Anderson, English Language Teaching Centre, University of Edinburgh 2012 9 3. Don't forget to learn the word stress of a new word. Every English word has its own normal stress pattern. For .
