Taxonomic Affinities of Audubon's Shearwater from Europa Island

Abstract

The western Indian Ocean holds five subspecies of the pantropical Audubon's Shearwater (Puffinus lherminieri), but none was known to breed in the Mozambique Channel. Here, I describe a newly discovered population of Audubon's Shearwaters on Europa Island, southern Mozambique Channel. Comparison of geographic variation of morphometric characters showed that the birds of this population belong to the P. l. bailloni subspecies, previously thought to be endemic to the Mascarenes Islands. They were distinct from the three subspecies of the Comoro, Aldabra, and Seychelles group, suggesting that few successful exchanges of individuals occur between north of the Mozambique Channel and Europa Island. This biogeographic pattern is similar to that of two phylogenetically independent pelagic species from Europa Island. This suggests that a common cause related to geographic isolation and oceanic conditions in the Mozambique Channel may explain the apparent isolation of these three seabird populations from Europa Island.