CLIFF-NESTING ADAPTATIONS OF THE GALiPAGOS SWALLOW-TAILED GULL1

E CULLEN (1957) showed that the cliff-nesting Black-legged Kittiwake (Larus (Rissa) tridactylus) differs from “typical” (i.e., ground-nesting)‘ gulls in many respects. The species’ unique morphological and behavioral characters, Cullen cogently argued, have resulted from adaptation (either directly or indirectly) to cliff-breeding. Epistemologically, the correlation between cliff-nesting and unusual characters constitutes a hypothesis that must be “tested” independently on a relatively unrelated cliff-nesting gull. Therefore, while I was studying the chick-feeding behavior of the cliff-nesting Galapagos Swallow-tailed Gull (Larus (Creagrus) furcatus) I noted the general habits of this species for comparison with the Kittiwake.