Regulation of Bald Eagle Reproductive Rates in Southeast Alaska

Hansen, Andrew J.

doi:10.2307/1939222

Cited by 69 publications

(61 citation statements)

References 17 publications

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“…Bald eagles generally feed on waterfowl, marine birds, terrestrial mammals, and a variety of intertidal, and freshwater fishes (Knight, Randolph, Allen, Young, & Wigen, 1990), but the 5 species of Pacific salmon ( Oncorhynchus spp.) are numerically dominant in eagle diets (Hansen, 1987). Bald eagles were found throughout the park, nesting in white spruce ( Picea glauca ) and cottonwood ( Populus tricocarpa ) trees along lake shores, streams, and coastlines; ground nests were found occasionally.…”

Section: Methodsmentioning

confidence: 99%

“…Bald eagle nesting, nest success, and chick production are dependent on various factors including food availability and weather conditions (Gende & Willson, 1997; Hansen, 1987). These factors can also interact to influence hatching dates and reproductive rates, as observed in golden eagles ( Aquila chrysaetos ) by Steenhof, Kochert, and McDonald (1997).…”

Section: Introductionmentioning

confidence: 99%

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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: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nest use dynamics of an undisturbed population of bald eagles

Wilson

Schmidt

Mangipane

et al. 2018

Ecology and Evolution

View full text Add to dashboard Cite

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“…Not surprisingly, average rearing success is improved with increased food availability during the nesting period, even though this variable does not appear to influence initial clutch size (Hansen, 1987).…”

Section: Breeding Biologymentioning

confidence: 94%

“…Thus, in southeastern Alaska the incidence of nonbreeding in adults increased from 26 to 86 percent between (Hansen and Hodges, 1985, and it appears that this phenomenon may be associated with intense intraspecific competition and highly variable annual food supplies. Although average clutch size is apparently not related to food availability, offspring survival, the timing of early laying, and the proportion of active nests may all be influenced by food availability (Hansen, 1987).…”

Section: Social Behaviormentioning

confidence: 95%

Hawks, eagles, & falcons of North America: biology and natural history

1991

Choice Reviews Online

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“…Factors affecting reproductive success not well known, but most discussion is related to association with DDT levels. In an Alaska study, vegetative characteristics of the habitat were only weakly related to reproductive success (Hansen 1987 Little recorded mortality related to exposure beyond indirect effects through food supply (Buehler 2000). Reproduction, however, may be reduced during cold, wet springs (Buehler 2000 …”

Section: Management Implicationsmentioning

confidence: 99%

Vulnerability of species to climate change in the Southwest: threatened, endangered, and at-risk species at Fort Huachuca, Arizona

Bagne¹,

Finch²

2013

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Future climate change is anticipated to result in ecosystem changes, and consequently, many species are expected to become increasingly vulnerable to extinction. This scenario is of particular concern for threatened, endangered, and at-risk species (TER-S) or other rare species. The response of species to climate change is uncertain and will be the outcome of complex interactions and processes. Nevertheless, a simple flexible strategy is needed to help integrate climate change into management planning and actions. This assessment uses SAVS, a vulnerability scoring tool based on ecological principles, to rank individual species of interest within the Fort Huachuca region according to predicted climate change responses and associated population declines balanced with responses expected to incur resilience or population increases. Further, specific areas of vulnerability, research needs, and management implications are identified for each species. Based solely on predicted response to climate change, northern Mexican gartersnake and southwestern willow flycatcher are the most vulnerable to population declines. Results also suggest that climate change will make management of some TER-S more difficult. Several critical management areas are identified that can mitigate negative impacts to benefit multiple species, including fire and fuels, invasive species, natural and artificial waters, and landscape-scale planning. Management planning should be in place that will assist species impacted by extreme events such as prolonged drought, severe wildfires, and intense flooding. The assessment process was also used to identify areas where climate change may present opportunities, as opposed to challenges, for management of TER-S.

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Regulation of Bald Eagle Reproductive Rates in Southeast Alaska

Cited by 69 publications

References 17 publications

Nest use dynamics of an undisturbed population of bald eagles

Nest use dynamics of an undisturbed population of bald eagles

Hawks, eagles, & falcons of North America: biology and natural history

Vulnerability of species to climate change in the Southwest: threatened, endangered, and at-risk species at Fort Huachuca, Arizona

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