IMPACT OF RAT-SPECIES IN OUVEA AND LIFOU (LOYALTY ISLANDS) AND THEIR CONSEQUENCES FOR CONSERVING THE ENDANGERED OUVEA PARAKEET

This study assesses the impact of Pacific Rat Rattus exulans predation on the endangered Ouvea Parakeet Eunymphicus cornutus uvaeensis and i nvestigates the feasibility of translocating this bird to the island o f Lifou (despite the presence of Ship Rat R. rattus). A rat trapping c ampaign, conducted from July 1995 to October 1996 in the forest of Ouv ea and Lifou (Loyalty Islands, New Caledonia, South-west Pacific), con firmed the presence of Pacific Rats in Ouvea and both Pacific and Ship Rats in Lifou. Population dynamics, sex ratio, age structure and diet of both rats were investigated. An experiment, using quail eggs in na tural tree holes during the main bird breeding season, in Ouvea in 199 4 and in Ouvea and Lifou in 1996, compares the nest predation rate bet ween these islands. Mayfield's estimator for a 21 day theoretical incu bation period gives a survival rate of 0.80 and 0.99 in the two experi ments in Ouvea but only 0.22 in Lifou. Most of the difference in egg s urvival observed between the islands appears to be related to the pres ence of Ship Rat in Lifou, while the difference in the two experiments in Ouvea may estimate the effects of trapping. The study shows that L ifou is not a suitable place for translocating Ouvea Parakeets, unless active habitat management is carried out to protect this bird against Ship Rats. The value of low intensity rat control in Ouvea immediatel y prior to the parakeet breeding period is also suggested. (C) 1998 El sevier Science Ltd. All rights reserved.