Conservation significance of alternative nests of golden eagles

Millsap, Brian A.; Grubb, Teryl G.; Murphy, Regina M.; Swem, Ted; Watson, James

doi:10.1016/j.gecco.2014.11.017

Cited by 41 publications

(41 citation statements)

References 20 publications

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“…Recent improvements in our bald eagle sampling protocol (Wilson, Weiss, et al., 2017) through the inclusion of a second survey in early spring, will allow us to fit a more robust dynamic occupancy model in the future. Additionally, many raptors have more than one nest in a territory (Millsap, Grubb, Murphy, Swem, & Watson, 2015). We were not able to distinguish between alternative nests and unused primary nests, and therefore urge caution when interpreting our results in terms of territories or territorial pairs.…”

Section: Discussionmentioning

confidence: 99%

Nest use dynamics of an undisturbed population of bald eagles

Wilson

Schmidt

Mangipane

et al. 2018

Ecology and Evolution

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Management or conservation targets based on demographic rates should be evaluated within the context of expected population dynamics of the species of interest. Wild populations can experience stable, cyclical, or complex dynamics, therefore undisturbed populations can provide background needed to evaluate programmatic success. Many raptor species have recovered from large declines caused by environmental contaminants, making them strong candidates for ongoing efforts to understand population dynamics and ecosystem processes in response to human‐caused stressors. Dynamic multistate occupancy models are a useful tool for analyzing species dynamics because they leverage the autocorrelation inherent in long‐term monitoring datasets to obtain useful information about the dynamic properties of population or reproductive states. We analyzed a 23‐year bald eagle monitoring dataset in a dynamic multistate occupancy modeling framework to assess long‐term nest occupancy and reproduction in Lake Clark National Park and Preserve, Alaska. We also used a hierarchical generalized linear model to understand changes in nest productivity in relation to environmental factors. Nests were most likely to remain in the same nesting state between years. Most notably, successful nests were likely to remain in use (either occupied or successful) and had a very low probability of transitioning to an unoccupied state in the following year. There was no apparent trend in the proportion of nests used by eagles through time, and the probability that nests transitioned into or out of the successful state was not influenced by temperature or salmon availability. Productivity was constant over the course of the study, although warm April minimum temperatures were associated with increased chick production. Overall our results demonstrate the expected nesting dynamics of a healthy bald eagle population that is largely free of human disturbance and can be used as a baseline for the expected dynamics for recovering bald eagle populations in the contiguous 48 states.

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Section: Discussionmentioning

confidence: 99%

Nest use dynamics of an undisturbed population of bald eagles

Wilson

Schmidt

Mangipane

et al. 2018

Ecology and Evolution

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“…If the temporal patterns in nest-site use in our study reflected actual population trends (Sergio and Newton, 2003;Kennedy et al, 2014), there were likely key factors affecting local raptor populations independent of potential energy-development effects. Raptor occupancy, site fidelity, and population trends are known to be associated with local prey availability (Smith et al, 1981;MacLaren, et al 1988;Woffinden and Murphy, 1989;Kostrzewa, 1996;Kochert and Steenhof, 2002;Sergio et al, 2006;Millsap et al, 2015) which varies temporally and spatially (Fedy and Doherty, 2011;Simes et al, 2015). Raptor prey deficits can be exacerbated by exogenous factors such as Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Human activities such as energy development that encroach upon historic nesting habitats may elicit behavioral avoidance (Krüger, 2002;Coates et al, 2014;Johnston et al, 2014) or indirectly affect nesting success (Hethcoat and Chalfoun, 2015a). Because raptors tend to exhibit high fidelity to nesting areas (Newton, 1979;Millsap et al, 2015) and often reuse the same nests, changes in nest-site use over time could signal the existence of one or both of the aforementioned effects and warrant further examination. Monitoring activities that identify potential changes in raptor nesting habitat use with respect to energy development will be particularly important for management prescriptions geared towards maintaining sustainable raptor populations.…”

Section: Introductionmentioning

confidence: 99%

Raptor nest–site use in relation to the proximity of coalbed–methane development

Carlisle¹,

Sanders²,

Chalfoun³

et al. 2018

Anim. Biodiv. Conserv.

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Raptor nest-site use in relation to the proximity of coalbed-methane development. Energy development such as coalbed-methane (CBM) extraction is a major land use with largely unknown consequences for many animal species. Some raptor species may be especially vulnerable to habitat changes due to energy development given their ecological requirements and population trajectories. Using 12,977 observations of 3,074 nests of 12 raptor species across nine years (2003-2011) in the Powder River Basin, Wyoming, USA, we evaluated relationships between raptor nest-site use and CBM development. Our objectives were to determine temporal trends in nest-use rates, and whether nest-site use was related to the proximity of CBM development. Across the study area, nest-use rates varied across species and years in a non-linear fashion. We developed a novel randomization test to assess differences in use between nests at developed and undeveloped sites, while controlling for annual variation in nest-site use. Red-tailed hawks (Buteo jamaicensis), burrowing owls (Athene cunicularia), and long-eared owls (Asio otus) used nests in undeveloped areas more than nests in developed areas (i.e. nests near CBM development). Differences between development groups were equivocal for the remaining nine species; however, we caution that we likely had lower statistical power to detect differences for rarer species. Our findings suggest potential avoidance of nesting in areas near CBM development by some species and reveal that CBM effects may be fairly consistent across distances between 400-2,415 m from wells. Future work should consider habitat preferences and fitness outcomes, and control for other key factors such as local prey availability, raptor densities, and weather.

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“…The basic unit by which occupancy and productivity of raptors are measured is the nesting territory, and a nesting territory may include multiple alternative nesting sites (Sergio and Newton 2003;Millsap et al 2015;Anderson et al 2017). Because our data from overflights were derived from individual sites, a first step in our analyses was to delineate territories and assign individual sites to territories.…”

Section: Delineation Of Territoriesmentioning

confidence: 99%

Nonrandom territory occupancy by nesting Gyrfalcons (Falco rusticolus)

et al. 2019

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We know little regarding how specific aspects of habitat influence spatial variation in site occupancy by Arctic wildlife, yet this information is fundamental to effective conservation. To address this information gap, we assessed occupancy of 84 Gyrfalcon (Falco rusticolus Linnaeus, 1758) breeding territories observed annually between 2004 and 2013 in western Alaska. In line with the theory of population regulation by site dependence, we asked whether Gyrfalcons exhibited a nonrandom pattern of site selection and if heterogeneous landscape attributes correlated with observed occupancy patterns. We characterized high- and low-occupancy breeding territories as those occupied more or less often than expected by chance, and we evaluated land cover at 1 and 15 km circles centered around nesting territories to identify habitat variables associated with observed occupancy patterns. We tested 15 competing models to rank hypotheses reflecting prey and habitat variables important to nesting Gyrfalcons. We confirmed a nonrandom pattern of site selection but found only weak evidence that the distribution of prey habitat was responsible for this pattern. We reason that preferential habitat use by nesting Gyrfalcons may be determined by spatial scales other than those we measured or may be driven by landscape-level attributes at time periods other than during the brood rearing period.

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Conservation significance of alternative nests of golden eagles

Cited by 41 publications

References 20 publications

Nest use dynamics of an undisturbed population of bald eagles

Nest use dynamics of an undisturbed population of bald eagles

Raptor nest–site use in relation to the proximity of coalbed–methane development

Nonrandom territory occupancy by nesting Gyrfalcons (Falco rusticolus)

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