Estimates of Changes in Seabird Numbers in the Grand Manan Archipelago, New Brunswick, Canada

Publication Type:Journal Article
Year of Publication:2003
Authors:Ronconi1, RA, WONG, SARAHNP
Journal:Waterbirds
Volume:26
Issue:4
Date Published:2003
ISBN Number:1524-4695
Keywords:Alca, Alca torda, Alcidae, Anatidae, Canada, Cepphus, Cepphus grylle, Cymochorea leucorhoa, Hirundo, Hydrobates leucorhoa, Hydrobatidae, Hypoleucos auritus, Laridae, Larus, Larus argentatus, Larus fuscus, Larus marinus, Oceanodroma, Oceanodroma leucorhoa, Phalacrocoracidae, Phalacrocorax, Phalacrocorax auritus, Phalacrocorax carbo, Somateria, Somateria mollissima, Sterna, Sterna hirundo, Uria, Uria aalge
Abstract:Abstract A census of the Grand Manan Archipelago, New Brunswick, Canada, found nine seabird species nesting at 22 sites. Herring Gull (Larus argentatus) and Common Eider (Somateria mollissima) were the most widely distributed species, with a combined 89% of all breeding seabirds in the region. Although fewer, the Great Black-backed Gull (Larus marinus) and Black Guillemot (Cepphus grylle) were widely distributed. Other seabirds had more limited distributions; one Common Tern (Sterna hirundo) colony, three Double-crested Cormorant (Phalacrocorax auritus) colonies and one mixed colony of Razorbill (Alca torda) and Common Murre (Uria aalge). Leach?s Storm-Petrel (Oceanodroma leucorhoa) numbers were not determined, but were found nesting on three islands and were suspected to be nesting on two others. Comparisons with historical data showed increases in gulls, Razorbill and Common Murre, whereas eiders had remained relatively stable over the past two decades, but had decreased in recent years. Insufficient data are available to assess trends of other seabird species nesting around Grand Manan. Fluctuations in cormorant numbers may be a result of moving breeding sites. The recent decrease in eider numbers may be a consequence of low survival rates of young and increasing numbers of predatory gulls. Considerable discrepancies were observed between recent and historical gull numbers which may have resulted from 1) differences in survey methodology, and 2) survey timing. This study provides estimates of breeding seabirds, which can be used as baseline data for future monitoring in the Grand Manan Archipelago.Abstract A census of the Grand Manan Archipelago, New Brunswick, Canada, found nine seabird species nesting at 22 sites. Herring Gull (Larus argentatus) and Common Eider (Somateria mollissima) were the most widely distributed species, with a combined 89% of all breeding seabirds in the region. Although fewer, the Great Black-backed Gull (Larus marinus) and Black Guillemot (Cepphus grylle) were widely distributed. Other seabirds had more limited distributions; one Common Tern (Sterna hirundo) colony, three Double-crested Cormorant (Phalacrocorax auritus) colonies and one mixed colony of Razorbill (Alca torda) and Common Murre (Uria aalge). Leach?s Storm-Petrel (Oceanodroma leucorhoa) numbers were not determined, but were found nesting on three islands and were suspected to be nesting on two others. Comparisons with historical data showed increases in gulls, Razorbill and Common Murre, whereas eiders had remained relatively stable over the past two decades, but had decreased in recent years. Insufficient data are available to assess trends of other seabird species nesting around Grand Manan. Fluctuations in cormorant numbers may be a result of moving breeding sites. The recent decrease in eider numbers may be a consequence of low survival rates of young and increasing numbers of predatory gulls. Considerable discrepancies were observed between recent and historical gull numbers which may have resulted from 1) differences in survey methodology, and 2) survey timing. This study provides estimates of breeding seabirds, which can be used as baseline data for future monitoring in the Grand Manan Archipelago.
URL:http://dx.doi.org/10.1675/1524-4695(2003)026[0462:EOCISN]2.0.CO;2
Short Title:Waterbirds
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith