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The importance of survey timing in monitoring breeding seabird numbers

Waterbirds

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Abstract

We conducted weekly aerial surveys of islands along the central Maine coast from April-June of 1993-1997 and used aerial photographs to determine peak nest count dates for Double-crested Cormorants (Phalacrocorax auritus), Herring Gulls (Larus argentatus) and Great Black-Backed Gulls (Larus marinus). These data also were used to determine the potential effect of survey timing on the ability to detect long-term trends in the abundance of these species. The number of cormorant nests in the study area peaked in mid-June, while Great Black-backed and Herring gulls peaked in late May and early June, respectively. Peak nesting dates generally were consistent for each island across years, but varied by up to a month between islands during a given year. A 10-year monitoring program using annual surveys conducted between 23 May and 23 June, or biennial surveys conducted from 2-17 June, would have an 80% probability of detecting annual changes of ??5% for all three species in this region. Received 1 November 2000, accepted 4 December 2000.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The importance of survey timing in monitoring breeding seabird numbers
Series title:
Waterbirds
Volume
24
Issue:
1
Year Published:
2001
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
22
Last page:
33
Number of Pages:
12