Code

CCBTR-11-11

Publication Date

2011

Abstract

By the late 1960s, the Virginia bald eagle breeding population had been decimated by eggshell thinning and associated low productivity. In 1977, the U. S. Fish and Wildlife Service formed the Chesapeake Bay Bald Eagle Recovery Team. This team was tasked with developing a plan for the recovery of the Bay population. As part of this process, state wildlife agencies assumed the responsibility for population monitoring. The Virginia Department of Game & Inland Fisheries along with the College of William & Mary initiated a systematic survey in the spring of 1977. Since that time, the annual bald eagle survey has become an essential element of a successful conservation strategy. Our objectives in continuing the Virginia bald eagle nest survey are 1) to monitor the recovery of the bald eagle in Virginia, 2) to document the status, distribution, and productivity of breeding bald eagles in Virginia, 3) to provide information to the government agencies charged with the management and protection of the Virginia bald eagle population, 4) to provide information to land holders about the status of bald eagles on their properties, and 5) to increase our understanding of bald eagle natural history in Virginia. The Virginia bald eagle survey measures breeding activity and productivity via a standard 2-flight approach. The first flight is conducted between late February and mid-March to locate active nests. A high-wing Cessna 172 aircraft is used to systematically overfly the land surface at an altitude of approximately 100 m to detect eagle nests. All bald eagle nests detected are plotted on 7.5 min topographic maps and given a unique alpha-numeric code. Each nest is examined to determine its condition and activity status. The second survey flight is conducted from late April through mid-May to check active nests for productivity. During the 2011 breeding season, the annual survey documented 726 occupied bald eagle territories in Virginia. This number represents a 6.2% increase over 2010. More than 130 new nests were mapped. Occupied territories were located within 45 counties and 10 independent cities. The majority of known territories continue to be concentrated within the Coastal Plain with less than 5% of pairs occurring in the piedmont and mountains. A total of 938 chicks were counted during the productivity flight. This is the highest chick production recorded during the 35-year history of the survey. The Virginia population continues to have tremendous reproductive momentum. Of 11,030 chicks documented in the past 35 years, 8.5% were produced in 2010 and 73.2% were produced since 2000. In general, this momentum is the combined result of an overall increase in the breeding population, the breeding success rate and the average brood size.

Species

Bald Eagle

Source

Center for Conservation Biology Technical Report Series. College of William and Mary and Virginia Commonwealth University, Williamsburg, VA.

Pages

38

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