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
Great shearwater can be seen in large numbers from ships or appropriate headlands. They have a piercing "eeyah" cry usually given when resting in groups on the water. Great shearwater The great shearwater ("Ardenna gravis"; formerly "Puffinus gravis") is a large shearwater in the seabird family Procellariidae. "Ardenna" was first used to refer to a seabird by Italian naturalist Ulisse Aldrovandi in 1603, and "gravis" is Latin for "heavy". The great shearwater's relationships are unclear. It belongs in the group of large species that have been separated as genus "Ardenna" (Penhallurick & Wink 2004); within these, it might be allied with the