Allowable take of black vultures in the eastern United States

Zimmerman, Guthrie S.; Millsap, Brian A.; Avery, Michael L.; Sauer, John R.; Runge, Michael C.; Richkus, Kenneth D.

doi:10.1002/jwmg.21608

Cited by 18 publications

(28 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We conducted PTL analyses using two variations on the underlying discrete logistic model, one assuming a linear relationship in density dependence (Runge et al, 2009), and the other allowing for nonlinear density dependence, the theta‐logistic model (Gilpin et al, 1976; Johnson et al, 2012; Zimmerman et al, 2019). The theta‐logistic model is specified as

PTL goodbreak= F_{o} goodbreak\times \frac{r_{\max} \times italicθ}{italicθ + 1} goodbreak\times N,

where θ is a shape parameter that describes the form of density dependence.…”

Section: Methodsmentioning

confidence: 99%

Age‐specific survival rates, causes of death, and allowable take of golden eagles in the western United States

Millsap

Zimmerman

Kendall

et al. 2022

Ecological Applications

Self Cite

View full text Add to dashboard Cite

In the United States, the Bald and Golden Eagle Protection Act prohibits take of golden eagles (Aquila chrysaetos) unless authorized by permit, and stipulates that all permitted take must be sustainable. Golden eagles are unintentionally killed in conjunction with many lawful activities (e.g., electrocution on power poles, collision with wind turbines). Managers who issue permits for incidental take of golden eagles must determine allowable take levels and manage permitted take accordingly. To aid managers in making these decisions in the western United States, we used an integrated population model to obtain estimates of golden eagle vital rates and population size, and then used those estimates in a prescribed take level (PTL) model to estimate the allowable take level. Estimated mean annual survival rates for golden eagles ranged from 0.70 (95% credible interval = 0.66–0.74) for first‐year birds to 0.90 (0.88–0.91) for adults. Models suggested a high proportion of adult female golden eagles attempted to breed and breeding pairs fledged a mean of 0.53 (0.39–0.72) young annually. Population size in the coterminous western United States has averaged ~31,800 individuals for several decades, with λ = 1.0 (0.96–1.05). The PTL model estimated a median allowable take limit of ~2227 (708–4182) individuals annually given a management objective of maintaining a stable population. We estimate that take averaged 2572 out of 4373 (59%) deaths annually, based on a representative sample of transmitter‐tagged golden eagles. For the subset of golden eagles that were recovered and a cause of death determined, anthropogenic mortality accounted for an average of 74% of deaths after their first year; leading forms of take over all age classes were shooting (~670 per year), collisions (~611), electrocutions (~506), and poisoning (~427). Although observed take overlapped the credible interval of our allowable take estimate and the population overall has been stable, our findings indicate that additional take, unless mitigated for, may not be sustainable. Our analysis demonstrates the utility of the joint application of integrated population and prescribed take level models to management of incidental take of a protected species.

show abstract

PTL goodbreak= F_{o} goodbreak\times \frac{r_{\max} \times italicθ}{italicθ + 1} goodbreak\times N,

where θ is a shape parameter that describes the form of density dependence.…”

Section: Methodsmentioning

confidence: 99%

Age‐specific survival rates, causes of death, and allowable take of golden eagles in the western United States

Millsap

Zimmerman

Kendall

et al. 2022

Ecological Applications

Self Cite

View full text Add to dashboard Cite

show abstract

“…If the population continues to increase and allowable take appears to remain sustainable as we continue to update monitoring and demographic data, managers may revisit the management objectives for bald eagle allowable take. The use of a PTL framework based on nonlinear density dependence, as has been done with other raptor species (Zimmerman et al 2019, Millsap et al 2022, also contributed to higher take estimates but to a lesser extent than increased population sizes given that the estimate of allowable take based on nonlinear density dependence was only approximately 1.2 times (risk averse) or 1.4 times (median estimate) higher than the linearbased estimate across all eagle management units. Allowable take estimates assuming nonlinear density dependence were less precise than under the linear assumption, which was due to uncertainty in the estimate of θ.…”

Section: Allowable Take Of Bald Eaglesmentioning

confidence: 97%

Estimating allowable take for an increasing bald eagle population in the United States

et al. 2022

Self Cite

View full text Add to dashboard Cite

Effectively managing take of wildlife resulting from human activities poses a major challenge for applied conservation.Demographic data essential to decisions regarding take are often expensive to collect and are either not available or based on limited studies for many species. Therefore, modeling approaches that efficiently integrate available information are important to improving the scientific basis for sustainable take thresholds. We used the prescribed take level (PTL) framework to estimate allowable take for bald eagles (Haliaeetus leucocephalus) in the conterminous United States. We developed an integrated population model (IPM) that incorporates multiple sources of information and then use the model output as the scientific basis for components of the PTL framework. Our IPM is structured to identify key parameters needed for the PTL and to quantify uncertainties in those parameters at the scale at which the United States Fish and Wildlife Service manages take. Our IPM indicated that mean survival of birds >1 year old was high and precise (0.91, 95% CI = 0.90-0.92), whereas mean survival of first-year eagles was lower and more variable (0.69, 95% CI = 0.62-0.78). We assumed that density dependence influenced recruitment by affecting the probability of breeding, which was highly imprecise and estimated to have declined from approximately 0.988 (95% CI = 0.985-0.993) to

show abstract

“…, Zimmerman et al. ). PBR is defined as a fixed harvest rate that may be applied to a population, while allowing that population to reach or maintain some optimum (Runge et al.…”

Section: Conceptual Frameworkmentioning

confidence: 99%

Assessing population‐level consequences of anthropogenic stressors for terrestrial wildlife

et al. 2020

View full text Add to dashboard Cite

Human activity influences wildlife. However, the ecological and conservation significances of these influences are difficult to predict and depend on their population-level consequences. This difficulty arises partly because of information gaps, and partly because the data on stressors are usually collected in a count-based manner (e.g., number of dead animals) that is difficult to translate into rate-based estimates important to infer population-level consequences (e.g., changes in mortality or population growth rates). However, ongoing methodological developments can provide information to make this transition. Here, we synthesize tools from multiple fields of study to propose an overarching, spatially explicit framework to assess population-level consequences of anthropogenic stressors on terrestrial wildlife. A key component of this process is using ecological information from affected animals to upscale from count-based field data on individuals to rate-based demographic inference. The five steps to this framework are (1) framing the problem to identify species, populations, and assessment parameters; (2) field-based measurement of the effect of the stressor on individuals; (3) characterizing the location and size of the populations of interest; (4) demographic modeling for those populations; and (5) assessing the significance of stressor-induced changes in demographic rates. The tools required for each of these steps are well developed, and some have been used in conjunction with each other, but the entire group has not previously been unified together as we do in this framework. We detail these steps and then illustrate their application for two species affected by different anthropogenic stressors. In our examples, we use stable hydrogen isotope data to infer a catchment area describing the geographic origins of affected individuals, as the basis to estimate population size for that area. These examples reveal unexpectedly greater potential risks from stressors for the more common and widely distributed species. This work illustrates key strengths of the framework but also important areas for subsequent theoretical and technical development to make it still more broadly applicable.

show abstract

Allowable take of black vultures in the eastern United States

Cited by 18 publications

References 24 publications

Age‐specific survival rates, causes of death, and allowable take of golden eagles in the western United States

Age‐specific survival rates, causes of death, and allowable take of golden eagles in the western United States

Estimating allowable take for an increasing bald eagle population in the United States

Assessing population‐level consequences of anthropogenic stressors for terrestrial wildlife

Contact Info

Product

Resources

About