Trans-equatorial migratory shearwaters aggregate in the North Atlantic

David Boertmann (Institute of Bioscience, Aarhus University, Roskilde, Denmark) has looked at seabirds, including Great Puffinus gravis, Sooty P. griseus and Cory's Calonectris diomedea Shearwaters, in the North Atlantic, publishing his findings in Marine Ornithology.

The paper's summary follows:

"From 12 to 17 September 2006 a "snapshot" of seabird densities in the northern Atlantic between Greenland and the Azores was obtained using the strip-transect method.  Relatively high densities of seabirds in the Greenland shelf and subpolar waters as well as very low densities in the oceanic subtropical waters, described by early authors, were confirmed.  Highest oceanic densities (average 21 individuals/km² per subtransect) were observed on 15 September approximately 200 km south of the subpolar front at about 50°N and approximately 600 km west of the Mid-Atlantic Ridge.  Most numerous in this area were Leach's Storm-Petrel (552 on-transect), Great Shearwater (317 on-transect) and Cory's Shearwater (125 on-transect), and noteworthy were small numbers of Arctic Terns and Long-tailed Skuas.  This high-density site was located in the centre of the stopover site/foraging area recently discovered by tracking Arctic Terns, Long-tailed Skuas, Sooty Shearwaters and Cory's Shearwaters.  This combined aggregation area seems to be associated with the subpolar front between the Grand Banks and the Charlie-Gibbs fracture zone.


Cory's Shearwater.  Photograph by John Graham

Reference:

Boertmann, D. 2011.  Seabirds in the central North Atlantic, September 2006: further evidence for an oceanic seabird aggregation area.  Marine Ornithology 39: 183-188.

John Cooper, ACAP Information Officer, 15 February 2012

The Agreement on the
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ACAP is a multilateral agreement which seeks to conserve listed albatrosses, petrels and shearwaters by coordinating international activity to mitigate known threats to their populations.

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