Western jackdaw amounts of silicaceous and calcareous grit to aid digestion of vegetable food and supply dietary calcium. Opportunistic and highly adaptable, the western jackdaw varies its diet markedly depending on available food sources. They have been recorded taking eggs and nestlings from the nests of the skylark ("Alauda arvensis"), Manx shearwater ("Puffinus puffinus"), razorbill ("Alca torda"), common murre ("Uria aalge"), grey heron ("Ardea cinerea"), rock pigeon ("Columba livia"), and Eurasian collared dove ("Streptopelia decaocto"). A field study of a large city dump on the outskirts of León in northwestern Spain showed that western jackdaws forage there in the early morning and
Galápagos shearwater Galápagos shearwater The Galápagos shearwater ("Puffinus subalaris") is a small shearwater. Until recently it was considered to be a subspecies of Audubon's shearwater, but it is actually one of two members of a very ancient lineage of the small "Puffinus" species, the other being, as indicated by mtDNA cytochrome "b" sequence data, the Christmas shearwater. It is an endemic breeder of the Galápagos Islands, and is largely sedentary, although individuals are commonly seen as far as the Oaxacan coast of Mexico. The Galápagos shearwater has dark brown upperparts, undertail and underwing flight feathers, the rest of the underparts plumage being