Aerial Photography Techniques to Estimate Populations of Laughing Gull Nests in Jamaica Bay, New York, 1992-1995

Abstract

-We evaluated aerial photography (full coverage, using fixed-wing aircraft) and aerial video (transects, using helicopter) surveys to estimate the population of Laughing Gull (Larus atricilla) nests in Jamaica Bay, New York, duringJune 1992-1995. We counted 4,920 nests in the colony using aerial photography and estimated 5,367 nests using aerial video in 1992. In 1993-1995, we respectively counted 5,691, 5,095, and 6,126 nests in the colony using aerial photography, and estimated from ground plots that our counts differed from the actual number of nests by means of-9% to 1%. Overall (1993-1995) correction factors (by which to multiply the aerial photography nest counts) to estimate the mean and 95% lower and upper CI range of the nest population were 1.04, 0.96 and 1.13, respectively. Ninety-seven percent of nests identified using aerial photography or video had >1 adult Laughing Gull present or within 1 m of the nest. The aerial video survey was less expensive ($2,100 United States currency) than the aerial photography survey ($4,000). The estimated cost of a total count of nests from the ground is $6,700$9,600. The aerial video survey provided an accurate estimate of the number of nests. Full-coverage aerial photography also provided an accurate estimate of nests in addition to habitat, nest distribution and nest density data. Received 13 June 1996, accepted 3 October 1996.