Landscape‐scale redistribution of a highly mobile threatened species,Pteropus conspicillatus (Chiroptera,Pteropodidae), in response to Tropical Cyclone Larry

Abstract Severe category 4 Tropical Cyclone Larry, which crossed north‐east Queensland on 20 March 2006, provided a unique opportunity to examine the short‐term impacts of a major disturbance event on the population of a highly mobile threatened species, Pteropus conspicillatus. As we had recorded, the species’ population distribution in colonial roosts (camps) across the region each month for almost 2 years prior to Cyclone Larry, we continued monthly surveying of P. conspicillatus camp‐sites for a year post‐cyclone. Here we report on how P. conspicillatus responded and redistributed immediately after the cyclone, and over the subsequent year. Post‐cyclone, P. conspicillatus typically roosted in smaller camps than pre‐cyclone, suggesting that these animals had largely dispersed to locate available blossoms and fruit. For 6 months after Cyclone Larry, up to 90% of the pre‐cyclone P. conspicillatus population (ca. 250 000) was unaccounted for across the region. Information provided by the general public assisted us in locating six small camps of P. conspicillatus at ‘new’ locations, but contributed little to increase our overall population estimate for the species at this time. After November 2006, the number of P. conspicillatus built up at located camp‐sites until a post‐cyclone peak of 209 000 at the end of the study in March 2007, comparable with the population estimates in March 2005 and 2006. There is no evidence that the cyclone caused significant direct mortality among P. conspicillatus, although there may yet be longer‐term and indirect effects on population size. We suggest that redistribution by P. conspicillatus makes sense ecologically in the face of major habitat disturbance and short‐ to long‐term food resource limitation, and is not unlike the response of other Australian mainland Pteropus species to seasonal changes in food availability.