INTERINSULAR VARIATIONS IN THE SPRING AND SUMMER DIET OF THE RAVEN CORVUS-CORAX IN THE CANARY-ISLANDS

This paper presents the first data on the diet of the Raven Corvus cor ax in the Canary Islands, based on analysis of 2315 pellets collected from all of the islands and islets in the archipelago. The Ravens on t hree groups of island showed differences in diet, but in all cases the diet was clearly omnivorous, both in its qualitative and quantitative composition. It is evident that a broadening of the Raven's trophic n iche has occurred in comparison with those living in continental areas . While the diet has a strong plant component on the wetter islands (f requency of occurrence >87%), an appreciable animal component in the d iet (principally vertebrates) is more frequent on the drier islands of the archipelago (frequency of occurrence >96%). The composition of th e plant component of the diet varied markedly from one island to anoth er. Remains of refuse are more commonly found in the Raven's diet on t he central and western islands. We concluded that while the animal die t is essential from the bioenergetic point of view, the vegetation die t is only a complementary food source. The Raven plays an important ro le in seed dispersal among the different habitats within each island.