Estimating Survival and Population Trajectories of Golden Eagles in Nevada.

Golden Eagle (Aquila chrysaetos) populations in western North America have recently been reported as stable. Vital rates, however, can vary geographically and across life stages to the extent that local population sources and sinks may form. The little-studied population in Nevada is of particular interest in this regard based on its large contribution to the species' breeding population in the western USA. Our investigation in Nevada focused on additive and synergistic factors that may set local populations on a different course than regional or range-wide estimates. However, little is known about Golden Eagle populations in the state. We investigated the survival of Golden Eagles in Nevada, including a breeding population near a proposed solar energy development area in southern Nevada. We used a multistate model to estimate survival by age class, and parameterized population projection matrix models to predict intrinsic rates of population change. We found strong evidence that the Golden Eagle population in Nevada is declining, which is likely related to low survival estimates across age classes. Investigations at the time of transmitter recovery indicated a minimum of 6 of 18 attributable mortalities likely resulted from anthropogenic causes. Additive mortality related to drought, reduced prey base, and habitat loss experienced by Golden Eagles in Nevada suggests the potential for the existence of a population sink within the state, and we highlight the need for closer management of Golden Eagle populations in this rapidly changing landscape. [ABSTRACT FROM AUTHOR]