Reptiles are uncommon as seabird predators on islands. While conducting a study on Cory's Shearwaters (Calonectris diomedea) on Selvagem Grande, North Atlantic, incidental observations during 2006 early hatching period indicated that some chicks were being killed by Madeiran Wall Lizards (Teira dugesii). In the same year and in 2007, the phenomenon was further examined and samples of 78 and 153 nests, respectively, were followed. Also, non-systematic visits were made to other nests. A total of 40 episodes of lizards depredating Cory's Shearwaters hatchlings was recorded. This hitherto unknown source of predation for this shearwater accounted for the failure of four (5.1%) study nests in 2006 and eight (5.2%) study nests in 2007. All recorded predation cases took place either during or shortly after hatching. Also, non-systematic observations indicated that three other species of burrowing petrels (Bulwer's Petrel, Bulweria bulwerii; Madeiran Storm-petrel, Oceanodroma castro, White-faced Storm-petrel, Pelagodroma marina) were preyed upon by Madeiran Wall Lizards. Predation by lizards is apparently a phenomenon of lesser concern for Cory's Shearwaters but the potentially higher impact over the smaller petrel species is not known.
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Vol. 32 • No. 4