The objective of this project is to demonstrate and validate an approach to assess the role of lead and disturbance as stressors on bald (Haliaeetus leucocephalus) and golden eagles (Aquila chrysaetos) on military installations. The approach uses feathers and blood collected at nests, assays to screen those tissues for lead, stress hormones, and enzymes related to lead contamination, all evaluated relative to military training and testing activities, recreational hunting, and landscape characteristics. This research will allow Department of Defense (DoD) managers to assess sublethal “take” of these protected species and to provide mitigative strategies to minimize impacts thereof. The project will evaluate these factors singularly and in combination using informative models to show how they contribute to potential deleterious stress to raptors, thus allowing installations to assess risk and develop appropriate mitigation strategies. Project goals are to 1) demonstrate tools and approaches to evaluate toxicant exposure, stress levels, and stress response of raptors at and near military installations throughout the United States; 2) identify linkages among stressors (military activity, recreational hunting as a toxicant exposure source) and indicators of physiological stress hormones and enzymatic stress response; 3) provide guidance documents for DoD natural resources staff and environmental chemistry laboratories to collect and analyze data to evaluate indirect and sublethal effects of activities on military installations to wildlife; and 4) demonstrate the use of a predictive tool to identify installations with potential for raptors to be negatively impacted by sub-lethal stressors.
The technologies to adapt and apply for this project consist of: (a) field data and tissue sample collection; and using tissue to evaluate (b) stress hormone levels; (c) lead exposure; and (d) physiological (enzyme and hormone) response activity, in birds. Fieldwork will involve (1) identifying raptor nest locations on installations; (2) collecting shed feathers from adult birds; (3) collecting regurgitated pellets from nests; (4) monitoring nest success and collection of nestling feathers and blood; (5) characterizing military training and testing, via remote Audio Recording Units; and (6) conducting automated camera surveillance and feather collection at hunter kill-sites to document frequency of and exposure to ammunition fragments. Although these available technologies have been applied in isolation and to other biological systems, the innovative approach will, for the first time, evaluate longer-term and sex-specific stress responses of birds linking both corticosterone and lead in feathers to animal origins identified with stable hydrogen isotope analyses to direct field observations. Lead in the blood of nestlings will indicate recent exposure and can be linked to indicators of physiological harm from tissue assays. Success in this project will be indicated by completion of the last step in the process as the response metric and then integrating these data in novel ways to understand how disturbance and exposure to toxicants affect raptors at military installations by modeling their relationship to testing and training, and impacted sources such as from hunting.
This approach benefits DoD by providing: 1) new tools and synthesis approaches to assess sublethal impacts from Mission and stewardship activities to raptors with high conservation status and regulatory designation; 2) the ability to integrate disparate data types to quantify disturbance and impacted burdens on raptors; 3) data to inform managers on how spatio-temporal mitigation can minimize impacts to raptors; 4) informative predictive models to allow installations to assess initial risk with minimal field effort and cost. Presently, there is no framework to assess sublethal stressors of wildlife on DoD facilities. This work will provide a cost-effective workflow process usable by managers. Importantly, this work will assist DoD in complying with federal laws protecting migratory birds, including eagles.