Colonization of an island volcano, Long Island, Papua New Guinea, and an emergent island Motmot, in its caldera lake. IV. Colonization by non-avian vertebrates

Abstract

Aim. In a 1999 expedition we surveyed the non-avian vertebrates recolonizing a volcanic island off the north coast of Papua New Guinea, and the more recently emerged islet in its caldera lake. It is our intention with this research to document the reassembly of an ecosystem after a cataclysmic event at two temporal stages.

Location. Long Island, 55 km north of Papua New Guinea, erupted explosively in the seventeenth century. Its biota was destroyed and the island has been recolonized by animals and plants. From about 1953 to 1968, an island, Motmot, emerged from Long's freshwater caldera lake about 4 km from the nearest shore.

Methods. For 15 days in 1999 we surveyed the mammals, reptiles and amphibians of Motmot and the western parts of Long.

Results. We assess the present fauna as thirteen mammals, fourteen reptiles and two amphibians.

Main conclusions. Long appears to have a high proportion of tramp-type species in its bat fauna, indicative of a developing biota. Several groups, especially snakes and amphibians, appear to be depauperate compared to the fauna of other islands in the area. On Motmot we recorded only one species of insectivorous bat; its vertebrate fauna is still in the very first stages of development.