Banded geckos, Gekko vittatus (Reptilia, Gekkonidae), as the main prey of barn owls (Tyto alba) on the Torres Islands (northern Vanuatu)

Abstract

A large sample of bones representing prey remains of barn owls (Tyto alba) was collected from the surface of the floor of a cave on Toga Island, Torres Islands, a remote island of northern Vanuatu. These remains allowed us to obtain a first overview of the prey of barn owls on that island, knowing that elsewhere mammals constitute the major prey group. The dominant prey species were banded geckos (Gekko vittatus—47% of prey individuals found in our bone sample) followed by rats (Rattus spp.—35%). Also present were lesser numbers of other gecko species (Gehyra oceanica, Nactus multicarinatus), skinks (Emoia spp.), birds, and bats. Data show that nocturnal birds of prey remain important predators of large geckos on Toga Island. This finding contradicts interpretations of other late historical (following human colonisation), non-cultural bone assemblages from barn owls from other Pacific islands, where rats have replaced geckos as primary prey. The same situation as reported on Toga Island occurs in other places like the Canary Islands where barn owls also prey predominantly on an endemic gecko species. These observations suggest that the barn owl is an opportunistic predator taking whatever prey is available. The unanswered question is why geckos are the most frequent prey of barn owls on some islands and not on others.