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
Christmas shearwater Christmas shearwater The Christmas shearwater ("Puffinus nativitatis") is a medium-sized shearwater of the tropical Central Pacific. It is a poorly known species due to its remote nesting habits, and it has not been extensively studied at sea either. It is one member of a very ancient lineage of the small "Puffinus" species. Its only close living relative is the Galápagos shearwater ("P. subalaris"). The species was described and given its current binomial name by the American naturalist Thomas Hale Streets in 1877. A genetic analysis using mitochondrial DNA has shown that the closest living relative is the Galápagos shearwater ("Puffinus