Golden Eagles in the U.S. and Canada: Status, Trends, and Conservation Challenges

j RaptorRes. 36(1 Supplement):32-40 ¸ 2002 The Raptor ResearchFoundation, Inc.

GOLDEN EAGLES IN THE U.S. AND CANADA: STATUS, TRENDS, AND CONSERVATION CHALLENGES

MICHAEL N. KOCHERT AND KAREN STEENHOF USGS,Forest and RangelandEcosystem Science Center, Snahe River Field Station, 970 LushStreet, Boise,1l) 83706 U.S.A.

ABSTRACT.--Wereviewed the literature to assessstatus and population trends and to identify mortality factorsaffecting Golden Eagle populationsin the U.S. and Canada. Nesting populationsin Alaskaand Canada are stable, but some nesting populations in the western U.S. have declined. Small but steady declinesin the intermountain West have been associatedwith shrub lossand decliningjackrabbit populations; declines in southern California have been attributed to urbanization. Migration countsin the easternU.S. suggesta decline in Golden Eaglesfrom the 1930sto the early 1970s,with a stableor increasingtrend sincethe early 1970s.No significanttrends in migrationcounts were reported for Golden Eaglesin the westernU.S. sincethe mid-1980s.Western migration count siteson the continental divide in the Rocky Mountains at or just north of the U.S.-Canadianborder (49-51øN latitude) show potential to provide information on trendsof Golden Eagle populationsfrom Alaskaand westernCan- ada. Most eaglemortality is human related. This paper illustratesthe need for more effectivemonitoring of Golden Eagle populationsin North America. K•¾ WOP,DS: GoldenEagle; Aquila chrysaetos;status; monitoring; mortality; U.S.; Canada.

Aguilasreals en E.U.A. y canad•t:estado, tendencias y retos para su conservaci0n RESt)MEN.--Revisamosla literatura para evaluarel estadoy las tendenciaspoblacionales y para identificar los factoresde mortalidad qne afectanlas poblacionesde/tguila real en E.U.A. y Canad/t.Las poblaciones que anidan en Alaska y Canad•t est•m estables,pero algunas poblaciones que anidan en el oeste de E.U.A. hah declinado. Pequefias, pero continuas declinaciones en el oeste intermontafioso hah sido asociadascon la perdida de arbustosy con el decline en las poblaciones de liebres; el declive en el sur de California ha sido atribuido a la urbanizaci6n.Conteos migratorios en el estede E.U.A. sugierenun declineen las•tguilas reals desde los aftos 1930s hasta principios de los 1970s,con nna tendenciaestable o a incrementardesde el principio de los 1970s.Ninguna tendenciasignificativa en conteosde migratorios fue reportada para las •guilas reals en el oestede E.U.A. desdemediados de los 1980s.Los sitios de conteo de migraci6n del oeste sobre la dMsoria continental en las montafias rocosasen o justo al norte de la frontera E.U.A.-Canad•t (49-51 ø latitud N) tiene potencial para proveer de informaci6n sobre las tendenciasde las poblacionesde •tguilasreals de Alaskay el oestede Canad•. La mayoria de la mortalidad de las 5guilas esta relacionada con los humanos. Este articulo ilustra la nccesidadde nn monitoreo mas ei•ctivo de las poblacionesde •tguila real en Notre America. [Traducci6n de C•sar M/trquez y Victor Vanegas]

Until recently Golden Eagles (Aquila chrysaetos) Americans to the U.S. Fish and Wildlife Service to were considered abundant in North America with harvest Golden Eaglesfor religious purposeshave stablepopulations (Hamerstrom et al. 1975,Pahn- prompted the need to assessthe statusof the spe- er 1988). However,some studies,particularly those cies in North America and to assessthreats to pop- from migration count sites in the U.S. (e.g., Bed- ulations (Bart et al. 1999). In this paper, we report narz et al. 1990, Hoffman et al. 1992), have raised information on the status and trends of Golden questions about trends of Golden Eagle popula- Eagle populationsin the U.S. and Canada, and we tions. Only Pbur nesting Golden Eagle pairs are discussmortality •actors affecting eagle popula- known in the eastern U.S in Maine, Tennessee, tions.

and Georgia with two pairs the result of introduc- METHODS tion efforts in Tennesseeand Georgia (Kochert et We obtained information from published and unpub- al. 2002). In addition, recent requestsby Native lished literature and personal interviewswith individuals

32 MARCH 2002 GOLDEN EAGLE STATUS AND TRENDS IN NORTH AMERI(LA 33

Table 1. Trends in number of occupiednesting territories at four long-term surveyareas in the U.S.

LOCATION YEARS N a TREND SOURCE

Interior Alaska 1988-99 58-76 Stable Mcintyre and Adams 1999, Mcintyre 2001 Southwestern Idaho 1971-99 28-35 Decline* Steenhof et al. 1997, USGS, unpubl. data Northeast Colorado 1972-90 7-10 Decline Leslie 1992 Southern California 1895-1999 40-85 Decline Bittner and Oakley 1999

• Number of territories. * P < 0.001. conductinglong-term surveysof Golden Eagles.We used clines (Table 1). The number of occupied territo- a varietyof data including long-term nestingsurveys, the ries in southwestern Idaho declined significantly Breeding Bird Survey (Peterjohn 1994), ChristmasBird Counts (Sauer et al. 1996), and migration counts. Other between 1971 and 1994 (r • = -0.54, P < 0.001; sourcesincluded modeling efforts and other literature Steenhofet al. 1997). Declinesof nestingeagles In syntheses. southwestern Idaho were associated with loss of To assesslong-term trends in territory occupancyand shrubs and black-tailedjackrabbit (Lepus californi- productivity,we selectedstudies that spannedmore than 10 yr and extended into at leastthe mid-1980s.Four stud- cus)habitat due to widespreadfires (Kocherr et al. ies fit the criteria for occupancy(Table 1), and four fit 1999). Nesting eagles in San Diego County de- criteria for productivity(Table 2). Continuousstudies of creaseddramatically from an estimated85 pairs in both occupancyand productivity occurred only in the 1900 to 40 occupied territories in 1999 (Bittner Snake River Birds of Prey National Conservation Area (NCA) in southwestern Idaho (Steenhof et al. 1997, and Oakley 1999). Large-scaledeclines occurred USGS unpubl. data) and in Denali National Park in in- between 1956-80, and subtle declines occurred terior Alaska (Mcintyre and Adams 1999, Mcintyre through 1999. These declines were related to ex- 2001). Occupancydata from San Diego County, Califor- tensiveresidential development (Bittner and Oak- nia spanmore than 100 yr and were collectedby several ley 1999). The decline reported for northeastern investigators(Bittner and Oakley 1999), including Dixon (1937) and Scott (1985). Leslie (1992) comparedoccu- Colorado (10 to 7 pairs) should be interpreted pancyin northeasternColorado during two seasons18 yr with caution becauseof the small sample size and apart. We obtained productivityinformation ik)r Utah low frequencyof sampling (Leslie 1992). The num- from Keller and Smith (1998) and Bates and Moretti ber of nestingattempts in central Oregon declined (1994) (Table 2). In addition, we used the number of egg-layingpairs during 20 seasonsin centralOregon (An- significantly (r• = -0.69, P < 0.001) between derson 1985). 1966-84 (Anderson 1985). It is not clear if this decline was the result of a decrease in occupancyor RESULTS in the proportion of pairs that laid eggs. Nesting Territory Occupancy. Of four areas Eagle Productivity. In contrast to territory oc- tracked for long-term occupancyof eagle territo- cupancy,no long-term trends in productivity were ries, all except interior Alaska experienced de- reported except in north-central Utah (Table 2).

Table 2. Trends in Golden Eagle productivityin four long-term surveyareas in the U.S. Productivityis young fledged per pair except for north-centralUtah where it is young per egg-layingpair.

LOCATION YEARS N TREND SOURCE

Interior Alaska 1988-99 58-76 None Mcintyre and Adams 1999, Mcintyre 2001 Southwestern Idaho 1971-99 28-35 None Steenhof et al. 1997, USGS unpubl. data North-central Utah 1977-98 31-240 Decline* Keller and Smith 1998 Eastern Utah 1981-92 39 None Bates and Moretti 1994

* P = 0.02. 34 KOCHERT AND STEENHOF VOL. 36, No. 1 SUPPLEMENT

Table 3. Golden Eagle trends from Breeding Bird Sur- Table 4. Golden Eagle trends from Christmas Bird veys, 1966-98. Counts, 1959-88.

REGION TREND N a P REGION TREND P

All U.S.b 2.4 271 0.23 Surveywide - 1.0 <0.05 Pacific region 4.3 99 0.17 Stateswith declines Southwestregion -6.6 21 0.25 Idaho - 1.4 <0.001 CMP • 2.8 151 0.36 Oregon -2.4 <0.001 Canada - 7.1 5 0.56 Kansas - 3.7 <0.05 Surveywide 1.9 276 0.33 Number of routes with eagle observations. ExcludingAlaska. ing populations have been found recently at Hud- Central mountains and plains. son Bay in northern Quebec (Morneau et al. 1994) and in the Labrador Peninsula. Nesting populations in southwestern Saskatchewan and the Yukon Although eagle productivity has fluctuated with Territory are stable, with the latter being a large changesin the major prey in Alaska,southwestern population (estimated900-1000 pairs). Long-term Idaho, and easternUtah, the number of the young productivity of eagles in the Northwest Territories fledged per occupied territory showed no trends is also stable (Kirk and Hyslop 1998). White (1994) over time (Bates and Moretti 1994, Steenhof et al. reported that the status of Golden Eagles in the 1997, Mcintyre and Adams 1999). However, the western U.S. was variable: stable in some areas and proportion of young fledged per egg-layingpair possiblydeclining in others. Hunt et al. (1999) declinedslightly but significantly(r • = -0.22, P = modeled the breeding Golden Eagle population at 0.02) in the desert (lower elevation) study area of Altamont Pass in central California and concluded north-central Utah (Keller and Smith 1998). This that the population waseither stableor decreasing. decline in productivity may reflect loss and degra- Winter Surveys. According to results of Christ- dation of native sagebrush (jackrabbit) habitats mas Bird Counts, Golden Eagles declined signifi- (Keller and Smith 1998). cantly throughout the U.S. and Canada (Ontario Breeding Bird Surveys.Breeding Bird Surveys and British Columbia) from 1959-88 (Table 4). (BBS) showno trend for nesting Golden Eagleson Counts in Idaho, Oregon, and Kansasdeclined sig- either a regional or continental scale from 1966- nificantly, while other survey regions showed no 98 (Table 3). Long-term data from BBS routes are significant trend. However, ChristmasBird Counts available only in the southern portions of the Ca- have limited value for detecting Golden Eagle nadian provinces,and these resultsmay not be re- trends because of the low number of individuals liable becauseonly five routes had eagle observa- counted on each survey, inconsistenciesamong tions (Table 3). Data from Alaska and the Yukon years in survey efforts and area surveyed,and the and Northwest Territories of Canada where Gold- fhct that most surveysare in suburban,exurban, or en Eagles are abundant (Kirk and Hyslop 1998, rural settingswhere eaglesare least likely to occur. Mcintyre 2001) were not included in theseanalyses Aerial surveyscoordinated by the U.S. Fish and because BBS did not establish routes in these re- Wildlife Service (USFWS) provide potentially use- gions until the 1980s (Peterjohn 1994) and the ful infbrmation on wintering Golden Eagle densi- number of routes and routes with eagle sightings ties and adult:immature ratios (USFWS unpubl. are low. Most BBS routes follow roads (Peterjohn data). Between 1972-80, 124000 km 9 were sam- 1994) and becauseGolden Eaglesgenerally nest in pled from random transectsin Colorado, Idaho, remote areas (Pahner 1988), the BBS is not the Montana, New Mexico, Utah, and Wyoming during most reliable method to assesstrends of nesting January-February. Only the area in southern Ida- Golden Eagles. ho was surveyedafter 1980 and for more than 10 Trends Based on Other Information. Golden Ea- yr (Kocheft et al. 1984). This 18 000-kin• area was gle nestingpopulations and productivityin Canada alsosurveyed in Octoberfrom 1972-78.Counts av- are likely stable; evidence for this assessmentin- eraged 2.56 more eaglesduring midwinter than in cludes considerable unpublished information October, suggestingan influx of migrant birds. (Kirk and Hyslop 1998). In eastern Canada, nest- The southern Idaho area contained both resident MARCH 2002 GOLDEN EAGLE STATUS AND TRENDS IN NORTH AMERICA 35

'• 3

0 i i i [ i i i i i i 72 73 74 75 76 77 78 79 80 81 82 83 84

Year Figure 1. Densitiesof Golden Eagleswintering in southernIdaho, 1973-84.

birds and migrantsfrom Alaskaand Canadaduring unpubl. data). Data from Ontario (Hussell and the winter (Fuller et al. 1995, Craig and Craig Brown 1992) and five migration sitesin the eastern 1998, Mcintyre 2000). Wintering densitiesin south- U.S. (Titus and Fuller 1990) suggestat least a sta- ern Idaho correlated strongly with black-tailed ble trend for Golden Eagle counts from the early jackrabbit abundance (Kocherr 1980). Because 1970s to the late 1980s. jackrabbit populations cycle about every 10 yr Migration Count Sites in the Western U.S. and (Johnson and Peek 1984), inferences from data Canada. Unlike migration count sites in the east- setscovering lessthan 10 yr can be misleading. Ea- ern U.S., continuous counts in the western U.S. gle countsfrom 1973-80 showeda significantde- span little over a decade (Table 6). Passagerates cline in southern Idaho (r = -0.80; P = 0.02) that at four migration count sitesshowed no trend fYom coincided with a jackrabbit decline (Kocherr the mid-1980s to late 1990s (Table 6). These sites 1980), but longer-term analysesthat included the occur south of 42øN latitude, and eaglesthat pass jackrabbit recovery showedthat winter eagle den- through them are probably a mix of northern mi- sitieswere stablefrom 1973-84 (Fig. 1). grants and dispersing resident birds or short-dis- Migration Count Sites in the Eastern U.S. and tance migrants (J. Smith pets. comm.). These Canada. We assessedtrends of migrating Golden Hawkwatch International sites report possible Eagles in the eastern U.S. and Canada from six changesin eagle age ratios that may reflect dete- migration count sites (Table 5). Passage rates riorating conditions in the western U.S. (J. Smith (number of Golden Eagles per 10 hr of observa- pets. comm.). Passagerates of immature Golden tion) declined significantly at Hawk Mountain, Eagles at the Wellsville Mountains in northern Pennsylvaniabetween 1934-72 but remained rela- Utah were significantlylower from 1987-97 than tively stable between 1973-86 (Bednarz et al. from 1977-79. 1990). From 1987-99, trends for Golden Eaglesat Raptor migration count siteson the continental Hawk Mountain have been stableor increasing(L. divide in the Rocky Mountains just north of the Goodrich pers. comm., Hawk Mountain Sanctuary U.S.-Canadian border show potential for monitor-

Table 5. Golden Eagle trends at migration count sitesin the eastern U.S. and Canada.

LOCATION YEARS SEASON TREND SOURCE

Hawk Mountain, Pennsylvania 1934-72 Autumn Decline Bednarz et al. 1990 1973-86 Autumn None Bednarz et al. 1990 Niagara Peninsula, Ontario 1975-90 Autumn Increase Hussell and Brown 1992 5 Eastern U.S. sites a 1972-87 Autumn/Spring None Titus and Fuller 1990 • IncludesHawk Mountain, Pennsylvania;Hawk Ridge, Minnesota;Whitefish Point, Michigan;Derby Hill, New York; and Cape May, New Jersey. 36 KOCHERT AND STEENHOF VOL. 36, No. 1 SUPPLEMENT

Table 6. Golden Eagle population trends at four migra- tering eagles captured in southeastern Idaho be- tion count sites in the western United States. • tween 1990-97 (Craig and Graig 1998), and 56% of 86 spring migrantsin Montana trapped between LOCATION SEASON YEARS TREND 1985-93 (Harmata and Restani 1995). Sources of Wellsvilles, Utah Autumn 1987-97 none b lead hwce not been documented definitively, but Goshutes, Nevada Autumn 1983-97 none are likely from lead shot or bullets in hunter-killed Manzanos, New Mexico Autumn 1985-97 none upland game birds and mammals (Wayland and Sandias,New Mexico Spring 1985-98 none Bollinger 1999), particularly deer (Pattee et al. Source:Hoffinan et al. unpubl. data,J. Smith, pers. comm. 1990) and ground squirrels(Harmata and Restani Passagerates for immatureswere significantlylower from 1987- 1995) with waterfowl as a secondary source. Mor- 97 than tkom 1977-79. tality from ingested shot and bullet fragments oc- curs occasionally(P. Redig pers. comm.). Blood lead levels of recaptured wintering individualsin ing trends becauseof the large number of eagles Idaho did not decreaseover 1-5 yr, suggestingre- that pass over them (Sherrington 1993). For ex- peated or continual exposure to lead in the envi- ample, fall countsat Mount Lorette (50ø58'N) in ronment (Graig and Graig 1998). Four (13%) of southern Alberta aweraged 4014 Golden Eagles 31 dead Golden Eagles examined from 1990-96 (range 3706-4599) between 1993-96, and spring from the GanadianPrairie Provinceshad been poi- countsweeraged 3707 (range 2461-4213) between soned and three (10%) were sublethallyexposed 1993-98 (Sherrington 1998, 1999). Although to lead (Wayland and Bollinger 1999). In Idaho, counts hwcebeen conducted since 1984 at Windy seven of 16 dead Golden Eagles necropsied be- Point (50ø40'N) and 1992 at Mount Lorette (Sher- tween 1977-86 were lead poisoned (Graig et al. rington 1998), data hwce not been analyzed for 1990). Agricultural pesticides,mainly organophos- trends. phates and carbamates,accounted for most of the Conservation Challenges. The greatest conser- remaining poisoningdeaths. In the latter cases,ea- vation challenge in managing Golden Eagle pop- gles often died by consuming other animals that ulations is offsetting the adverse effects of human were poisonedor by consumingbaits placed to kill activity. Of Golden Eagles found dead from the other wildlife. early 1960s to the mid-1990s, 73% died from hu- DISCUSSION man-related causes, including accidental trauma (27%), electrocution (25%), shooting (15%), and Nesting Golden Eagles. Although data provide poisoning (6%; Franson et al. 1995). Accidental conflicting evidence on population trends, weail- trauma included collisions with cars, fences, wires, able information suggeststhat nestingpopulations and wind turbines. At least 28-43 Golden Eagles in Alaska and Canada are stable and, for the most are killed each year by turbine blade strikesin the part, doing well. The statusof nesting Golden Ea, Altamont Pass Wind Resource Area in west-central glesin the westernU.S. is lessclear. Although some California; of 61 eagle deaths investigatedin the data, such as the BBS, suggeststable populations Diablo Rangebetween 1994-97, 37% resultedfrom throughout the western U.S., some populations turbine strikes, 5% from car strikes, and 3% from hwee declined. Areas like the Snake River Birds of fence collisions (Hunt et al. 1999). Golden Eagles Prey National Conservation Area may hwee expe- continue to be electrocuted in the western U.S and rienced a decreasein carrying capacity (Steenhof Canadawhere Harness(1997) reported 272 eagle et al. 1997). Shrub loss and declining jackrabbit electrocutions between 1986-96. Electrocution populations have been associatedwith small, but countedfor 16% of the Golden Eagledeaths in the steady, declines in the intermountain West; de- Diablo Range, California between 1994-97 (Hunt clines in southern California hwee been attributed et al. 1999). to urbanization. Although some nesting popula- Lead accounted for most poisoning deaths of tions in the westernU.S. hweedecreased, produc- Golden Eagles. Elevated lead levels (>0.20 ppm) tivity has not declined, except in one population occurred in 36% of 162 eaglessampled in 1985- This agrees with observationsof other eagle spe- 86 fi:om southern Califbrnia (Pattee et al. 1990). cies where lower quality (or lessproductive) terri- Elevated levels also occurred in 46% of 281 win- tories are abandoned in some declining popula- MARCH 2002 GOLDEN EAGLE STATUS AND TRENDS IN NORTH AMERICA 37

tions before productivity at higher quality ticularly in areas that have been surveyed in the territories declines (Ferrer and Donazar 1996). past (see Kirk and Hyslop 1998). Long-term data Contusions from Migration Counts. Migration sets from areas such as north-central Utah (Keller counts in the eastern U.S. suggest a decline in and Smith 1998) should be analyzedand evaluated Golden Eaglesfrom the 1930sto the early 1970s, to determine if these areas should become addi- with a stable or increasing trend since the early tional long-term monitoring sites.The area in cen- 1970s. No significant trends were reported for tral Oregon studied by Anderson (1985) also Golden Eagles in the West since the mid-1980s. should be resurveyedto ascertainif the population However, recent increases in adult detection rates is still depressedor whether it has rebounded. We and a decreasein migratory iramatureshave raised recommend monitoring the major prey (e.g., concern about conditions for breeding birds and black-tailed jackrabbits) concurrently with eagle possiblelowered reproduction of Golden Eaglesin nesting surveys, specifically in those areas w•th parts of the western U.S. (J. Smith pers. comm.). background prey data; i.e., the Snake River NCA Golden Eagle population trends from migration (Steenhof et al. 1997) and Denall National Park counts should be assessedjudiciously because of (Mcintyre and Adams 1999). inconsistenciesin data collection among yearsand We recommend that migration counts continue count sites,inconsistencies and biasesin assessing in the westernRocky Mountains >50øN latitude be- passagerates, and variability in counts and passage causethey have potential to reflect trends in west- rates causedby weather and eagle behavior (Gould ern Canada and Alaska.Counts at raptor migration and Lewis 1998, Fuller and Bates 1999). In addi- count sitesshould continue to be evaluated (e.g., tion, the origins and destinations of most birds Gould and Lewis 1998, Fuller and Bates 1999) to seen at migration count sitesare unknown. Signif- determine if they provide meaningful data about icant declines at a migration site could reflect statusand trend of eagle populations.Information problems throughout the range or merely at an also is needed about the origin and destination of isolated nesting or wintering area. It is difficult to eaglespassing through migration count sites. develop managementstrategies to addresspossible Counts of Golden Eagles along midwinter Bald causes of declines. Eagle (Haliaeetusleucocephalus) survey routes also Western migration count siteson the continental may provide long-term trend data. More than 300 divide in the Rocky Mountains at or just north of Golden Eagleshave been counted annually on 220 the U.S.-Canadian border (49-51øN latitude) show standard routes in 28 states since the mid-1980s potential to provide information on trends of (USGS unpubl. data). TheseJanuary countsoccur Golden Eagle populationsfrom Alaskaand western in Bald Eagle wintering habitat, which may not be Canada. Large numbers of Golden Eagles pass prime Golden Eagle habitat. The feasibilityof us- through these sites,and information from satellite ing numbers and age classesof Golden Eagles telemetry studies suggeststhese migration count counted on mid-winter Bald Eagle survey routes sites may be on a flight path for Golden Eagles for trend analysesshould be assessed. migrating from Alaskaand westernCanada (Fuller Winter aerial surveysalong transectsalso could et al. 1995, Mcintyre 2000). provide useful information about population Recommendations for Monitoring. Information trends, if they are conductedover at least 10 yr to we present in this paper illustratesthe need for span a completejackrabbit population cycle. Data more effective monitoring of Golden Eagle popu- from USFWS aerial surveysin six statesduring the lations in North America. We recommend that 1970smight providevaluable baseline data on win- long-term nesting surveyscontinue, specificallyin ter eagle densities and age ratios, if the surveys Denali National Park (Mcintyre 2001), the Snake were resumed. These surveysare repeatable be- RiverBirds of PreyNCA (Steenhofet al. 1997), and cause they were conducted on random transects San Diego County, California (Bittner and Oakley and sampled in a consistent fashion each year. 1999). Continuous data from these areas provide They also are relatively inexpensive to conduct; in valuableinsights about eagle responsesto different southern Idaho, we surveyed1600 km of transects, environmental problems in diverse geographical using 20 hr of aircraft time. These aerial surveys, areas. We recommend that surveyareas be devel- like the midwinter Bald Eagle counts, samplepop- oped for monitoring nesting eaglesin Canada, par- ulations that contain both the resident and mi- 38 I4•OCHERTAND STEENHOF VOL. 36, No. 1 SUPPLEMENT

grant birds. It is extremely difficult to attribute gle populations in North Annefica. Populations whether change in statusis a result of a change in must be monitored consistentlythroughout the the resident or migrant population or both. species' range, and well-designedinventory and An accurate evaluation of eagle population sta- monitoring protocols are essential to ensure the tus requires knowledgeabout statusand trend of future long-term stability of the Golden Eagle in floaters (nonterritorial, nonbreeding adults) in a North America. population in addition to the nesting segmentof LITERATURE CITED the population (Hunt 1998, Hunt et al. 1999, Bart et al. 1999). Stable populations contain an ade- ANONYMOUS.1997. Report of a workshopto develop a quate number of floaters that readily replace North American raptor monitoring strategy.Unpubl. breeding adults. Although difficult to obtain, ac- Rep. USGS SnakeRiver Field Station,Boise, ID U.S.A. curate assessmentof the floating segmentis critical ANDERSON,J. 1985. Observations of the Golden Eagle for assessingstatus of populations. Detecting de- (Aquila chrysaetos)in central Oregon. Unpubl. Rep. creasesin the proportion of floaters providesearly Oregon Dept. Fish Wildl., Bend, OR U.S.A. warning of population declines (Hunt 1998, Bart BART,J.R., E.A. ELLSWORTIi,M.R. FULLER,AND R.N. LEH- MAN. 1999. Plan for monitoring the statusof south- et al. 1999). Research is needed to develop a fea- western U.S. Golden Eagles.Poster presentation, Rap- sible means to efficiently gather information on tor Research Foundation Annual Meeting, La Paz, the proportion of floaters in populations. Mexico. Fall aerial surveysshow potential for assessing BATES,J.W. XNDM.O. MOP,•TTI.1994. Golden Eagle (Aq- changesin resident eagle populationsin the west- uila chrysaetos)population ecology in eastern Utah ern U.S. Surveysconducted in the early f•tll when Great Basin Nat. 54:248-255. young are dispersingfrom their nesting areasand BEDNARZ,J.C., D. lXd.EM,JR., L d. GOODPdCH,,•D S.E. SEN- just prior to arrival of migrants include all seg- NER.1990. Migration countsof raptors at Hawk Moun- ments of the population, including floaters,in the tain, Pennsylvania,as indicators of population trends, 1934-1986. Auk 107:96-109. survey area. Like the winter aerial surveys,these BITTNER,J.D. XNDJ. OAKLEY.1999. Statusof Golden Ea- fall surveys are repeatable and inexpensive, and gles in southern California. Golden Eagle Sympo- they should be conducted for at least 10 yr. Fall siren, Raptor ResearchFoundation Annual Meeting, surveyshave potential for migratory populationsif La Paz, Mexico. surveysare conductedafter youngdisperse, but be- CRAIC,,E.H. AND T.H. CRAIG.1998. Lead and mercury fore migration. levelsin Golden and Bald Eaglesand annual move- Another way to monitor Golden Eagle popula- ments of Golden Eagleswintering in eastcentral Ida- tions is to monitor the threats they face. Because ho 1990-1997. USDI, Bureau of Land Management, most eagle mortality is human-related,monitoring Idaho State Office, Boise, ID U.S.A. causesof death including electrocution,collisions, , J.W. CONNELLY,E.H. CRAIC.,AND T.L. PARKER 1990. Lead concentrations in Golden and Bald Ea- and lead levels should continue. gles. Wih'onBull. 102:130-133. Standard protocols for inventory and monitor- DIXON,J.B. 1937. The GoldenEagle in SanDiego Coun- ing must be establishedand followed to effectively ty, California. Condor39:49-56. assess status and trends of North American Golden FERRER,M. ANDJ.A. DONAZAR.1996. Density-dependent Eagle populations. We found it difficult to make fecundity by habitat heterogeneity in an increasing adequate assessmentsbecause of inconsistencies populationof SpanishImperial Eagles.Ecology 77:69- among sites and years and, even worse, inconsis- 74 tenciesamong yearswithin sites.The North Amer- F1LanNSON,J.C., L. SILEO,AND N.J. THOMAS.1995. Causes ican Raptor Monitoring Strategy (Anonymous of eagle deaths. Page 68 in E.T. LaRoe, G.S. Farris, 1997) mayprovide the necessaryvehicle to address C.E. Puckett, P.D. Doran, and M.J. Mac, lEDs.I, Our theseproblems. A goal of this strategyis to develop living resources.USD1, Natl. Biol. Serv., Washington, DC U.S.A. standard protocols fbr monitoring various raptor FULLER, M.R. AND K.K. BArrES. 1999. An evaluation of species,including Golden Eagles.Local declinesof hawk migration counts from North America: magni- Golden Eaglesand a recent request from Native tude of counts accumulated, disposal of data, and Americans to harvest this speciesin the southwest- their utility for indicies for monitoring populations ern U.S. have prompted the need for a range-wide Unpubl. Rep., USGS Patuxent Wildl. Res. Center, inventory and long-term monitoring of Golden Ea- Laurel, MD U.S.A. MARCH 2002 GOLDEN EAGLE STATUS AND TRENDS IN NORTH AMERICA 39

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