Status of the volcanically threatened Montserrat Oriole Icterus oberi and other forest birds in Montserrat, West Indies

The Montserrat Oriole Icterus oberi is endemic to the Caribbean island of M ontserrat where, prior to 1995, it was widely distributed across the island 's three main interior mountain ranges: the Centre, Soufriere and South Sou friere Hills. In July 1995, a long-dormant volcano on Chances Peak in the S oufriere Hills began to erupt. Since then the forest habitat of the oriole on the Soufriere and South Soufriere Hills has been devastated by pyroclast ic flows and surges, heavy ash eruptions and rock falls. The Montserrat Ori ole populations that inhabited these two mountain ranges have probably been lost. In December 1997, a census of the remaining Centre Hills population was undertaken to assess its status in the face of the heavy ash fall that occurred earlier the same year. To do this, a systematic grid of 140 sample points was overlaid on an area of 1,437.5 ha encompassing the Centre Hills , and a 10-minute count of all bird species was undertaken at 137 of these points during an eight-day survey period. The distance from the point to ea ch oriole detected was measured and records of all other species were alloc ated to one of five distance bands radiating out from the point. Distance s ampling was used to model densities, and thus to estimate population sizes, of eight bird species in the study area. It was estimated that 4,000 (95% CIs 1,500-7,800) Montserrat Orioles remain in the Centre Hills and thus the world. Although the probability of pyroclastic flows and surges overrunnin g the Centre Hills is considered remote, it is recommended that the Montser rat Oriole be classified as Globally Threatened (Endangered) under the revi sed IUCN threat categories because of its loss of breeding habitat since 19 95.