Abstract
Few studies have been made so far of inter-colonial and annual variation in the diet of breeding Great Cormorants Phalacrocorax carbo. We investigated their diet during the chick rearing period by collecting regurgitates from five breeding colonies, in the Chubu area, central Japan, in 2009-2011. Those cormorants breeding in coastal colonies took mainly Flathead Mullet Mugil cephalus cephalus and Dotted Gizzard Shad Konosirus punctatus, while those breeding in inland colonies took a wide range of fishes in any given year. The frequency of introduced Red Swamp Crayfish Procambarus clarkii and native Oriental River Prawn Macrobrachium nipponense in the diet increased in years when frequencies of fishes decreased, at both inland and coastal colonies.
