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Estimating populations of nesting brant using aerial videography

Wildlife Society Bulletin

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Abstract

We mounted a video camcorder in a single-engine aircraft to estimate nesting density along 10-m wide strip transects in black brant colonies on the Yukon Delta National Wildlife Refuge, Alaska during 1990-1992. A global positioning system (GPS) receiver was connected to the video recorder and a laptop computer to locate transects and annotate video tape with time and latitude-longitude at 1-second intervals. About 4-5 hours of flight time were required to record 30-40 minutes of video tape needed to survey large (>5,000 nests in > 10 km2)colonies. We conducted ground searches along transects to locate and identify nests for determining detection rates of nests in video images. Counts of nests from video transects were correlated with actual numbers of nests. Resolution of images was sufficient to detect 81% of known nests (with and without incubating females). Of these, 68% were correctly identified as brant nests. The most common misidentification of known nests was failure of viewers to see the nest that the detected bird was incubating. Unattended nests with exposed eggs, down-covered nests, and nesting brant, cackling Canada geese, and emperor geese were identified in video images. Flushing of incubating geese by survey aircraft was not significant. About 10% of known nests were unoccupied in video images compared to 16% unoccupied nests observed from tower blinds during periods without aircraft disturbance.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Estimating populations of nesting brant using aerial videography
Series title:
Wildlife Society Bulletin
Volume
23
Issue:
1
Year Published:
1995
Language:
English
Publisher:
U.S. Fish and Wildlife Service
Contributing office(s):
Alaska Biological Science Center
Description:
pp. 80-87
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Wildlife Society Bulletin
First page:
80
Last page:
87
Number of Pages:
8