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
Summerland Peninsula Bird Area. It is home to one of the largest Little Penguin ("Eudyptula minor") breeding colonies in Australia, the second largest breeding colony of Australian Fur Seals ("Arctocephalus pusillus doriferus") in the world, one of the largest breeding colonies of Greater crested terns ("Sterna bergii") in Victoria and an important breeding ground for Short-tailed shearwaters ("Puffinus tenuirostris"). Several plants regarded as rare or threatened in either Victoria or Australia have been recorded on the peninsula, including River Swamp Wallaby-grass ("Amphibromus fluitans") listed as vulnerable in Australia. The peninsula was significantly modified by agricultural, residential and recreational developments until the 1980s