Chris Bartlett recently photographed a flock of Ring-billed Gulls hovering over a mountain ash (Sorbus) while plucking fruit from the tree. His photo is here:
http://www.flickr.com/photos/101615744@N02/11205968464
The Ring-billed's counterpart in Europe is the Black-headed Gull, and those too have been observed feeding on Sorbus and cherries, along with Herring, Mew (Common), and many other species. California Gulls out west have been known to forage in cherry orchards. Ring-billed Gulls have also been seen feeding on crab apples (Malus), dates and other palm fruit, and Russian Olive (Elaegnus), and a paper on that was published here:
Komar, N. 2002. Ring-billed Gulls feeding on Russian-Olive fruit. Journal of the Colorado Field Ornithologists 36:32-34.
Here is a link to some Ring-billed Gulls feeding on Russian Olive in Montana:
http://www.radioactiverobins.com/BIRDSCAGE/sterns/gibraltar-fuengirola-dec07-jan2007/gulls%20fruitpicking-IMG_0870fullweb.jpg
This paper has an appendix listing a wide range of gull species eating fruit, some eating the fruit on the ground, but a number pluck the fruit from trees.
Calvino-Cancela, Maria. 2011. Gulls (Laridae) as frugivores and seed dispersers. Plant Ecology 212: 1149-1157
Abstract: Many gull species (Laridae) are opportunistic feeders with diverse diets. Seeds and fruits are common in gull diets, often in small proportions but sometimes dominant in certain periods and areas. Moreover, the large body sizes and high population densities of gulls increase their ecological importance. Hence, they can be significant seed dispersers even with relatively few seeds in diets. Gulls are highly mobile and have long gut-retention times, thus may provide long-distance dispersal for plants. Most information of the potential role of gulls as seed dispersers is from dietary studies, not focused on plant-animal interactions, thus the role of gulls on plant population dynamics is little known. Nevertheless, gulls have been shown to be effective dispersers of some coastal plants, and vectors for plant movement to and between islands. Here, I review this topic and hope to stimulate more research into the role of gulls as seed dispersers, particularly in coastal and island habitats.
Louis Bevier
Fairfield
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