Code

CCBTR-11-01

Publication Date

2011

Abstract

Bald Eagles were monitored at Naval Support Facility Indian Head, Maryland in compliance with a 2007 Biological Opinion prepared by the US Fish and Wildlife Service. Eagle nests were surveyed for breeding activity and productivity using a standard 2‐flight protocol. A Cessna 172 aircraft was used to systematically survey the property to locate eagle nests and determine nesting activity. Active nests were climbed with arborist equipment or accessed with a bucket truck. Forty‐nine Eagle nestlings were banded and measured. Blood and feather samples were collected from nestlings from 2008‐2010 to test for West Nile virus, mercury, heavy metals, PCB, and organochloride contaminants. Two addled eggs were collected for contaminant testing. Ten breeding territories were active during the 2008 ‐ 2010 breeding seasons. Productivity was 1.8 chicks/active nest (nest observed with eggs or chicks) and 2.07 chicks/productive nest (chicks reached fledging age). Two nestlings tested positive for exposure to West Nile Virus in 2009 but did not show signs of recent infection. Mercury levels were subacute in blood (ẍ = 0.04 mg/kg, n= 48) and feathers (x̄ = 1.24 mg/kg, n= 48). Contaminant levels in blood were also subacute for total PCBs (x̄ = 0.039 μg/g, n = 48), total Chlordane (x̄ = 0.006 μg/g, n= 48), and total DDT (x̄ = 0.011 μg/g, n= 48). The addled eggs had a mercury concentration of 0.07 mg/kg and 0.09 mg/kg, PCB levels of 18 ppm, and DDE of 3.7 and 5.6 ppm. Values for the addled eggs approached toxicity thresholds for polychlorinated biphenyls (PCB) and dichlorodiphenyldichloroethylene (DDE). Productivity rates recorded for pairs nesting on Indian Head were not significantly different from nests monitored along the Virginia portion of the Potomac River. A snow storm in early March 2009 caused widespread nest failures along the Potomac River including the Indian Head nests at Burn Point and Building 1569. All contaminant levels were low in nestling blood and feathers. High levels of PCB and DDE contaminants likely contributed to reproductive failure of the addled eggs at the Biazzi and Extrusion nests. High levels of these contaminants are present in nearby foraging areas along the Potomac River with point and non‐point source contamination documented upstream of NSF Indian Head. Two electrocutions occurred on NSF Indian Head during the study period. The breeding female at Burn Point was found dead during the 2008 breeding season after colliding with a powerline. The second electrocution occurred when a recently fledged chick from the 2009 Biazzi nest landed on an unprotected power pole approximately 730m from the nest.

Topic

Abundance/distribution; Breeding/Demography/Pop Dynamics

Species

Bald Eagle

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