A Population Estimate for Golden Eagles in the Western United States

Good, Rhett E.; Nielson, Ryan M.; Sawyer, Hall; McDonald, Lyman L.

doi:10.2193/2005593

Cited by 2 publications

(4 citation statements)

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“…Of these, an estimated 19,000-35,000 golden eagles reside in the western contiguous United States (Good et al, 2007;Millsap et al, 2013;Nielson et al, 2011).…”

Section: Evaluating Estimates Of Population Sizementioning

confidence: 99%

“…Monitoring programs are most effective and likely to be longlasting when they are low-cost and simultaneously gather large amounts of reliable information on populations (Good et al, 2007;Kéry, 2008). There are many examples of enduring and relatively inexpensive monitoring programs that use citizen-science volunteers to collect data (Braschler, 2009;Cohn, 2008;Devictor et al, 2010;Katzner et al, 2005;Mulder et al, 2010;Silvertown, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, the eastern population likely increased through the late 20th century (Farmer et al, 2008a). Estimates of the size of the eastern population ranges between 1000 and 5000 individuals Ombalski and Brandes, 2010), less than a quarter of the number of golden eagles in western North America-i.e., 19,000-35,000 (Good et al, 2007;Millsap et al, 2013;Nielson et al, 2011). Eastern golden eagles are counted in the hundreds at hawk-count sites in the central Appalachians.…”

Section: Introductionmentioning

confidence: 99%

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Integrating citizen-science data with movement models to estimate the size of a migratory golden eagle population

Dennhardt

Duerr

Brandes

et al. 2015

Biological Conservation

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a b s t r a c tEstimating population size is fundamental to conservation and management. Population size is typically estimated using survey data, computer models, or both. Some of the most extensive and often least expensive survey data are those collected by citizen-scientists. A challenge to citizen-scientists is that the vagility of many organisms can complicate data collection. As a result, animal-movement effects on data collection can adversely affect modeling of those data. Thus, it would be helpful to develop methods that integrate citizen-science datasets with models that account for animal movement. We used hawk-count data collected by citizen-scientists to estimate the number of golden eagles (Aquila chrysaetos canadensis) migrating through Pennsylvania, USA. To do this, we designed a computer model to simulate migratory flights of eagles to estimate what proportion of the population is available (i.e., within visible range or close enough) to be counted at hawk-count sites in Pennsylvania. We then conducted a multi-state mark-recapture analysis to estimate detection probability (i.e., the rate at which birds within visible range are observed) of migrating eagles. Finally, we used availability rates and detection probabilities to adjust raw hawk-count data to produce estimates of population size. Our models suggest that 24% (±14; mean ± SE) of migrating golden eagles are available to be counted at hawk-count sites, and that 55% (±1.6) of the available eagles are detected by hawk-count observers. We estimate that 5122 (±1338) golden eagles migrate annually through Pennsylvania. Our analysis provides the first quantitative estimate of the size of the eastern golden eagle population, and we demonstrate the utility of one approach to use citizen-science data to address a pressing conservation goal-population size estimation.

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“…Of these, an estimated 19,000-35,000 golden eagles reside in the western contiguous United States (Good et al, 2007;Millsap et al, 2013;Nielson et al, 2011).…”

Section: Evaluating Estimates Of Population Sizementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Integrating citizen-science data with movement models to estimate the size of a migratory golden eagle population

Dennhardt

Duerr

Brandes

et al. 2015

Biological Conservation

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“…reps.); new Golden Eagle nesting surveys are underway in New Mexico; and the U.S. Fish and Wildlife Service recently contracted for a large-scale aerial survey of Golden Eagles in the western U.S. (Good et al 2004). Thus, both monitoring and movement-ecology databases for this species are growing and, with time, improved understanding of Golden Eagle ecology will enhance our collective ability to accurately interpret migration count trends and assess this species' status and trends in western North America.…”

Section: Literature Citedmentioning

confidence: 99%

Do Golden Eagles Warrant Special Concern Based on Migration Counts in the Western United States? Reply to Mccaffery and Mcintyre

Hoffman¹,

Smith²

2005

The Condor

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In Hoffman and Smith (2003), we summarized two decades of raptor migration count data from western North America. McCaffery and McIntyre (2005) offer an extensive critique of the “conclusions” we drew from these data concerning the migration ecology and status of western Golden Eagles (Aquila chrysaetos). Many of their specific points about data limitations are well taken. Contrary to the flavor of their critique, however, we were not offering any definitive conclusions about the status or habits of eagles. Rather, we merely sought to describe the tendencies in the data and offer reasonable speculation about potential underlying causes of the documented patterns and trends. Our primary goal was to challenge colleagues to help us carefully consider our data and help formulate reasonable hypotheses about causal factors. We welcome and applaud McCaffery and McIntyre's (2005) thorough review of our work and genuine concern for guarding against unwarranted speculation. We believe, however that the depth of their critique was unjustified because the precision of the migration count data we presented simply is not sufficient to support detailed inspection of every annual change. Moreover, while we cannot disagree with them concerning the limits of the migration data we presented, we stand firmly behind our contention that there are indeed reasons to be concerned about the status of Golden Eagles in western North America, particularly within the sagebrush-steppe ecoregion. ¿Es el Estatus de Aquila chrysaetos Especialmente Preocupante de Acuerdo a los Conteos Migratorios del Oeste de los Estados Unidos?: Respuesta a McCaffery y McIntyre Resumen. En un trabajo previo (Hoffman and Smith 2003), resumimos datos sobre conteos de migración de rapaces realizados en el oeste de Norte América. McCaffery y McIntyre (2005) presentan una extensa crítica de las “conclusiones” que sacamos a partir de esos datos con respecto a la ecología de migración y el estatus de la especie Aquila chrysaetos. Muchos de sus argumentos específicos sobre las limitaciones de los datos son acertados. Sin embargo, en contraste con el tono de su crítica, en nuestro estudio no ofrecimos conclusiones definitivas sobre el estatus o los hábitos de A. chrysaetos. En cambio, simplemente quisimos describir las tendencias de los datos y presentar especulaciones razonables sobre las posibles causas de los patrones y tendencias documentados. Nuestro principal objetivo era desafiar a nuestros colegas para que nos ayudaran a considerar nuestros datos cuidadosamente y a formular hipótesis razonables sobre los factores causales. Por tanto, recibimos con beneplácito la revisión exhaustiva de nuestro trabajo hecha por McCaffery y McIntyre (2005) y su interés genuino en evitar especulaciones no fundamentadas. Sin embargo, creemos que la profundidad de su crítica no es justificable porque la precisión de los datos de los conteos de migración que presentamos es simplemente insuficiente para permitir la inspección detallada de todos los cambios anuales. Más aún, aunque no podemos estar en desacuerdo con ellos en cuanto a las limitaciones de los datos que presentamos, mantenemos firmemente nuestro argumento de que de hecho existen razones para estar preocupados por el estatus de A. chrysaetos en el oeste de Norte América, particularmente en la ecorregión de estepas y matorrales de Artemisia.

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A Population Estimate for Golden Eagles in the Western United States

Cited by 2 publications

References 1 publication

Integrating citizen-science data with movement models to estimate the size of a migratory golden eagle population

Integrating citizen-science data with movement models to estimate the size of a migratory golden eagle population

Do Golden Eagles Warrant Special Concern Based on Migration Counts in the Western United States? Reply to Mccaffery and Mcintyre

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