Resumo
The Cory’s Shearwater Calonectris diomedea borealis breeds in the subtropical northeast Atlantic and is one of the most important
consumers in the pelagic system of the mid-North Atlantic. Stomach samples collected in the Azores in 2005 indicated that the blue jack
mackerel Trachurus picturatus (68.7% of individuals and 72.1% of overall mass) constituted most of the Cory’s shearwater diet during the
breeding season, in strong contrast with findings of a study in 1994, when their diet comprised mainly boarfish Capros aper, trumpetfish
Macroramphosus sp. and Atlantic saury Scomberesox saurus/Nanichthys simulans. No differences were found in diet between sexes and
between islands in 2005. Blue jack mackerel were probably caught in the Azores islands shelf area, during both short and long foraging
trips. Prey availability may have changed in response to changes in sea-surface temperatures and/or the frequency of feeding associations
with other top predators in the region.