Holocene vertebrate assemblages provide the first evidence for the presence of the barn owl (Tytonidae, Tyto alba) on Socotra Island (Yemen)

Abstract

We describe the vertebrate remains found in a Holocene deposit inside the Taiti Cave, Socotra Island (Yemen). The fossils were found in a sand dune occupying almost entirely the main cavity of the Cave, with some bones collected on the surface and the majority of them found under its surface, in particular below a tiny level of hardened sand, the latter probably related to a guano deposit. They were mostly isolated bones, but under the guano layer, some of them were aggregated and recognizable as belonging to owl pellets. The analysis of the vertebrate remains reveals a great prey diversity and, together with the location of the pellet accumulation and the almost perfect preservation of the remains, indicates that the deposit derived from a pellet accumulation made by Tyto alba. This hypothesis is corroborated by a Tyto alba beak fragment found in the Hoq cave, in a deposit of uncertain stratigraphic context. The data presented herein represent the first documented evidence of the presence of Tyto alba on Socotra Island and indicate the probable existence of a now extinct population of Tyto alba on the island during the Holocene, already extinct at the time of the first ornithological surveys during the XIX Century.