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
Europa Island 100 pairs, probably of the subspecies "Puffinus lherminieri bailloni" previously considered endemic to the Mascarene Islands), dimorphic egrets and Caspian terns. The island is also home to an endemic subspecies of white-tailed tropicbird ("Phaethon lepturus europae"). There are three species of landbirds present, one of which is an endemic subspecies of the Malagasy white-eye ("Zosterops maderaspatanus voeltzkowi"). Additionally, the island is also home to its own species of hissing cockroach. Climate is affected by the Agulhas Current with water temperatures usually above 30 °C, southeast trade winds during the (austral) winter and occasional cyclones. While the island has probably been