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
Persian shearwater off Oman and Socotra, Yemen, while "P. p. temptator" has been estimated to number fewer than 500 pairs on Moheli Island in the Comoros (reviewed by Brooke 2004). It is thought likely that more breeding colonies lie undiscovered elsewhere in the northern Indian Ocean (Onley and Scofield 2007), thus the total population probably includes more than 10,000 mature individuals. The population trend is believed to be downwards. Persian shearwater The Persian shearwater ("Puffinus persicus") is a seabird in the family Procellariidae formerly lumped in with Audubon's shearwater ("Puffinus lherminieri"). There are two listed subspecies of the Persian shearwater: After breeding,