Elizabeth K. Mojica

Species-specific accumulation of polybrominated diphenyl ether flame retardants in birds of prey from the Chesapeake Bay region, USA

Compared to organochlorines, little is known about polybrominated diphenyl ether (PBDE) contamination of birds of prey breeding in the Chesapeake Bay, the largest estuary in the U.S. This study examined and compared PBDE contamination in eggs of osprey, double-crested cormorant, brown pelican and peregrine falcon from this area. Several legacy persistent organic pollutants such as PCBs and DDE were also investigated. The level of urbanization of the landscape appeared to influence the level of PBDE exposure. PBDE congener distribution patterns varied between piscivorous and terrestrial-feeding birds. This suggests individual congeners may be subject to differences in bioaccumulation, biomagnification or metabolism in the aquatic and terrestrial food webs. Biomagnification of PBDEs was studied in the Bay aquatic food chains for the first time. A biomagnification factor of 25.1 was estimated for SigmaPBDEs for the fish - osprey egg food chain. Hazard quotients, applied as a preliminary evaluation, indicated that PBDEs may pose a moderate hazard to ospreys and peregrine falcons through impairment of reproductive performance.

Status, Biology, and Conservation Priorities for North America's Eastern Golden Eagle (Aquila chrysaetos) Population

TODD KATZNER,1,2,26 BRIAN W. SMITH,3 TRICIA A. MILLER,4,5 DAVID BRANDES,6 JEFF COOPER,7 MICHAEL LANZONE,5,8 DANIEL BRAUNING,9 CHRISTOPHER FARMER,10 SERGIO HARDING,11 DAVID E. KRAMAR,12 CRAIG KOPPIE,13 CHARLES MAISONNEUVE,14 MARK MARTELL,15 ELIZABETH K. MOJICA,16 CHARLIE TODD,17 JUNIOR A. TREMBLAY,18 MARIA WHEELER,19 DAVID F. BRINKER,20 TONY E. CHUBBS,21 ROLF GUBLER,22 KIERAN O’MALLEY,23 SCOTT MEHUS,24 BRADY PORTER,19 ROBERT P. BROOKS,4 BRYAN D. WATTS,16 AND KEITH L. BILDSTEIN25

Factors Contributing to Bald Eagle Electrocutions and Line Collisions on Aberdeen Proving Ground, Maryland

Resumen Evaluamos los factores que contribuyen a las electrocuciones y las colisiones con los tendidos electricos de Haliaeetus leucocephalus en Aberdeen Proving Ground, un area importante de concentracion de aguilas en la bahia de Chesapeake. Durante el periodo de 1985 a 2007, documentamos la ubicacion de 62 aguilas muertas o recuperadas heridas bajo tendidos electricos. Usando un diseno de dos vias simple, superpusimos la mortalidad de las aguilas sobre segmentos del tendido, clasificados por su proximidad a la costa y por la altura de la vegetacion circundante. Documentamos una mortalidad significativamente mayor asociada con los tendidos mas cercanos a la costa comparada con los tendidos del interior que lo esperado con base en la longitud relativa del tendido (χ2 = 119.71, gl = 2, P < 0.001). Adicionalmente, el numero de muertes de aguilas asociado con los tendidos expuestos (sin vegetacion que los oculte) fue mayor que el esperado con base a la longitud relativa del tendido (χ2 = 11.54, gl = ...

Use of Satellite Transmitters to Delineate Bald Eagle Communal Roosts within the Upper Chesapeake Bay

Abstract Although Bald Eagle (Haliaeetus leucocephalus) roosts are protected under the federal Bald and Golden Eagle Protection Act, we have little systematic information on the distribution and abundance of roosts, and a policy framework that governs day-to-day management decisions has not been developed. We used satellite transmitters (n  =  63) deployed on Bald Eagles that represented a cross section of age classes and populations present within the study area. The units were programmed to record nocturnal roost locations (n  =  10 321) to assess roosting behavior and to delineate the boundaries of communal roosts within the upper Chesapeake Bay. More than 27% (n  =  2800) of roost locations were not associated with communal roosts and were assumed to reflect solitary roosting. The remaining 72% (n  =  7475) of roost locations were clustered within 170 communal roosts that varied in area (0.04–20.13 ha), relative use (5–755 roost-nights), and number of transmittered birds present (2–35). The number of communal roosts within the study area has grown 10-fold over the past 20 yr, presumably reflecting the growth of source populations and eagle use of the area. USO DE TRANSMISORES SATELITALES PARA DELINEAR DORMIDEROS COMUNALES DE HALIAEETUS LEUCOCEPHALUS EN LA BAHÍA ALTA DE CHESAPEAKE Aunque los dormideros de Haliaeetus leucocephalus están protegidos por la Ley Federal de Protección del Águila Calva y Dorada, poseemos poca información sistemática sobre la distribución y abundancia de los dormideros y no se ha desarrollado un marco político de decisiones diarias de manejo. Usamos transmisores satelitales (n  =  63) colocados en individuos de H. leucocephalus que representaron una muestra cruzada de clases de edad y poblaciones presentes en el área de estudio. Las unidades fueron programadas para registrar las localizaciones de los dormideros nocturnos (n  =  10 321) y así evaluar el comportamiento vinculado a los dormideros y delinear los límites de los dormideros comunales en la parte superior de la Bahía de Chesapeake. Más del 27% (n  =  2800) de las localizaciones de los dormideros no estuvo asociado con dormideros comunales y fueron considerados como dormideros solitarios. El 72% (n  =  7475) restante de las localizaciones de los dormideros fue agrupado en 170 dormideros comunales que variaron en superficie (0.04–20.13 ha), uso relativo (5–755 noches dormidero) y número de aves presentes con transmisores (2–35). El número de dormideros comunales dentro del área de estudio ha aumentado 10 veces a lo largo de los últimos 20 años, reflejando presumiblemente el crecimiento de poblaciones fuente y el uso del área por parte de las águilas.

Landfill Use by Bald Eagles in the Chesapeake Bay Region

Abstract We examined patterns in the use of landfills (rubbish dumps) in the Chesapeake Bay by Bald Eagles (Haliaeetus leucocephalus). Sites of solid waste landfills (n  =  72) were located using state databases. Satellite tracking data from 64 eagles were used to track eagle movements hourly during daylight and once at midnight to determine roosting locations (2007–2012). Landfill use varied significantly with age class, with hatch-year birds using landfills six times more often than adults and twice as often as third- and fourth-year birds. Hatch-year birds spent significantly more time at landfills than expected based on landfill area relative to the study area outside of landfills. The relationship between time of year and eagle presence at landfills was not significant, though the results suggest a peak in landfill use in the late fall. There was spatial variation in landfill use, with 10% of the landfills used by study birds receiving 75% of the total landfill use. Landfills within two km of communal roosts received significantly more eagle activity than landfills farther from communal roosting sites. If eagle presence at landfills is indicative of foraging at these sites, the results provide evidence that foraging strategies in Bald Eagles change with age. Landfills may serve as important scavenging sites for hatch-year and second-year eagles, whereas older birds may be more successful obtaining higher quality prey elsewhere.

Seasonal Variation in Space Use by Nonbreeding Bald Eagles Within the Upper Chesapeake Bay

Abstract Access to food resources is essential to self-maintenance and reproduction and, for species of conservation concern, foraging areas are considered critical habitat. Human disturbance is an important factor restricting access to prey resources for Bald Eagles (Haliaeetus leucocephalus) and guidelines in the Chesapeake Bay have been developed to mitigate its impact. However, our ability to implement such guidelines has been limited by a lack of information on important foraging areas. We used Brownian bridge movement modeling to develop a population-wide utilization probability surface for Bald Eagles along shorelines within the upper Chesapeake Bay. We used locations (n  =  320 304) for individuals (n  =  63) tracked with GPS satellite transmitters between 2007 and 2011 in the analysis. We examined seasonal variation by developing utilization surfaces for summer and winter. Although shoreline use was widespread, segments receiving high levels of activity were relatively rare. Shoreline classified as having the highest category of use and accounting for 10% of the total utilization made up 0.41% and 0.55% of the total shoreline for winter and summer, respectively. From a management perspective, there is a clear pattern of diminishing returns in conservation value for including sequentially lower-use shorelines in land-use management plans. Shoreline use shifted dramatically in both location and extent between seasons. During the summer months, use was highly concentrated on shorelines along the main stem of the Chesapeake Bay or along major (>1 km wide) tributaries. During the winter months, use shifted away from the main stem of the bay and was more focused on minor (<100 m wide) tributaries and inland ponds. Seasonal shifts in shoreline use suggest the need for season-based management objectives.

Utilization Probability Map for Migrating Bald Eagles in Northeastern North America: A Tool for Siting Wind Energy Facilities and Other Flight Hazards

Collisions with anthropogenic structures are a significant and well documented source of mortality for avian species worldwide. The bald eagle (Haliaeetus leucocephalus) is known to be vulnerable to collision with wind turbines and federal wind energy guidelines include an eagle risk assessment for new projects. To address the need for risk assessment, in this study, we 1) identified areas of northeastern North America utilized by migrating bald eagles, and 2) compared these with high wind-potential areas to identify potential risk of bald eagle collision with wind turbines. We captured and marked 17 resident and migrant bald eagles in the northern Chesapeake Bay between August 2007 and May 2009. We produced utilization distribution (UD) surfaces for 132 individual migration tracks using a dynamic Brownian bridge movement model and combined these to create a population wide UD surface with a 1 km cell size. We found eagle migration movements were concentrated within two main corridors along the Appalachian Mountains and the Atlantic Coast. Of the 3,123 wind turbines ≥100 m in height in the study area, 38% were located in UD 20, and 31% in UD 40. In the United States portion of the study area, commercially viable wind power classes overlapped with only 2% of the UD category 20 (i.e., the areas of highest use by migrating eagles) and 4% of UD category 40. This is encouraging because it suggests that wind energy development can still occur in the study area at sites that are most viable from a wind power perspective and are unlikely to cause significant mortality of migrating eagles. In siting new turbines, wind energy developers should avoid the high-use migration corridors (UD categories 20 & 40) and focus new wind energy projects on lower-risk areas (UD categories 60–100).

Impact of Renewable Energy Sources on Birds of Prey

Renewable energy is generated from natural processes that are replenished over time. Use of renewables reduces dependence of fossil fuels and reduces greenhouse gas emissions. These positive outcomes may be partially offset if renewables also have negative impacts. In this chapter, we evaluate potential direct and indirect impacts of renewables on birds of prey. We consider mortality, habitat loss, avoidance, and displacement at wind resource areas, biofuel agricultural sites, solar fields, and a variety of less-prevalent renewable energy facilities. We conclude that most renewable energy facilities are unlikely to have population-level effects on birds of prey, though individual territories likely are affected. However, specific sites, like wind resource areas in major bird of prey migration corridors or wintering areas, can have substantial effects. Industrial monocultures needed for biofuels also impact natural communities, including birds of prey. Developing solutions to mitigate these effects should be a conservation priority. Mitigation of bird of prey mortality at wind resource areas appears to be moving toward retrofitting power poles to prevent electrocutions, driven by the idea that reducing electrocution mortalities will compensate for inevitable collision mortalities. Mitigation for industrial monocultures involves setting aside conservation reserve areas as islands of habitat in seas of agriculture. It remains to be seen whether either of these approaches results in the actual conservation of the species, age, and sex classes affected by the processes being mitigated. Future research should compare the distributions of the specific individual birds of prey affected by renewable energy facilities (species, sex, age, conservation status, etc.), to the distributions of birds of prey benefitting from mitigation action.