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
Barolo shearwater introduced predators (rats and cats) must be their main threats at breeding colonies. In addition, fledglings are attracted to artificial lights at night during their maiden flights from nests to the sea. On Tenerife, Canary Islands, a decline on the number of birds attracted to lights have been reported, suggesting a population decline on the island. Barolo shearwater The Barolo shearwater ("Puffinus baroli"), also known as the North Atlantic little shearwater or Macaronesian shearwater, is a small shearwater which breeds in the Azores and Canaries of Macaronesia in the North Atlantic Ocean. "Puffinus" is a New Latin loanword based on