Inter-insular variation of the diet of osprey Pandion haliaetus in the Canarian archipelago

Abstract

We studied the diet of the osprey Pandion haliaetus in the Canary Islands during 1997-2008 using prey remains under perches and nests, and direct observations. We collected data both in breeding territories and in non-breeding areas. We counted a minimum of 307 fish individuals as prey remains (both during breeding and non-breeding seasons), and identified another 78 during 433 hours of field observations. According to our results, ospreys consumed at least 15 taxa belonging to 12 families. We found slight differences in the spatial (both intra and inter insular) and temporal diet composition. During the breeding season, the main prey species were flying fishes (belonging to the family Exocoetidae) and needlefishes (belonging to the family Belonidae) according to the two employed methods (i.e. prey remains and direct observations). In the non-breeding period, the diet was composed primarily of non-autochthones freshwater fishes such as common carp Cyprinus carpio and goldfish Carassius auratus. In general, the diet diversity was similar to the diversity reported in other breeding populations of subtropical areas, and being less diverse than those of tropical areas. More precise studies evaluating the effect of fish availability in marine reserves, overfishing areas or fish farms on the demographic parameters are necessary for the management and conservation of threatened Canarian ospreys