Sunday, July 8, 2012

Dietary specialization among the Glaucous-winged Gulls (Larus glaucescens) on Middleton Island

On Middleton Island a number of Glaucous-winged Gulls (Larus glaucescens) has specialized in taking alternative prey items. Some gulls out there are known to catch and eat young European feral Rabbits (Oryctolagus cuniculus) which were introduced to the island in 1954 (Roberts 1985; O'Farrell 1965). These two videos show how some Glaucous-winged Gulls try to catch a fledged Black-legged Kittiwake (Rissa tridactyla) chick and eat ripe Salmonberries (Rubus spectabilis) respectively. Further information can be found below the video on their individual Youtube pages.

It seems obvious that due to the island’s remote location the large Glaucous-winged Gull population has only limited access to terrestrial food items. Food shortage will therefore stimulate these birds more to explore new dietary items on the island. I am certain that there will be several more remarkable prey types utilized by them, and would very much appreciate it when visitors would inform me when they detect this.

O'Farrell, T.P. 1965. The Rabbits of Middleton Island, Alaska. Journal of Mammalogy, Vol. 46, No. 3, pp. 525-527
Roberts, B. 1985. Glaucous-winged Gulls prey on feral rabbits on Middleton Island, Alaska. Murrelet 66:24.

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