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
Buller's shearwater blackish also; the two black areas do not meet at the hand however; the area between them is a rather light grey, under bright light it may appear almost white. With the bird facing upwards, the pattern gives the impression of a broken black "M", with light grey interspersing areas. The underside is bright white; on the head the upperside's grey extends town to eye height and the white cheeks may shine up conspicuously, as in the smaller shearwaters of "Puffinus sensu stricto". The rectrices are blackish and the tail is wedge-shaped; bill and iris are dark. Fledged juveniles already