The ecology and conservation of the Christmas Island flying-fox (Pteropus natalis)

Abstract

On oceanic islands, where plants have coevolved with depauperate pollinator and seeddispersing guilds, flying-foxes (genus Pteropus) provide pollination and seed dispersal services that are vital for the maintenance of biodiversity. The high mobility of Pteropus species enable them to disperse seed and pollen across various island habitats, including disturbed areas where they are essential for the regeneration of forested habitats. However, despite their recognised importance, Pteropus species continue to decline across their range. More than 60% of Pteropus species are listed as Critically Endangered or Near Threatened. Declines in the population size of Pteropus species on islands has reduced their effectiveness as seed dispersers. Loss of Pteropus species could lead to cascades of linked extinctions due to unbalanced interactions among plant and animal communities. Therefore, it is essential to develop management strategies aimed at the recovery and conservation of Pteropus populations, particularly on islands. However, knowledge regarding the biology of the Pteropus genus is scant, and limited to a few species, hindering effective conservation management. One species of particular concern is the Critically Endangered Christmas Island flying-fox (Pteropus natalis) (Jackson and Groves 2015). Like many of Christmas Island's endemic species, the population of P. natalis has substantially declined in recent years. Furthermore, following the extinction of two rat species (Rattus nativitatis and Rattus macleari), one shrew (Crocidura trichura), and the most recent extinction of the Christmas Island pipistrelle (Pipistrellus murrayi) in 2009, P. natalis is currently the last remaining native mammal on Christmas Island. Like many other Pteropus species, the biology of P. natalis is poorly understood, and data on the species' life-history and ecological requirements are urgently needed to inform effective management interventions to help the recovery of this ecologically important species. Over the course three years, I spent 17 months collecting field data to address information gaps in the species' life-history and ecological requirements. This thesis has provided a detailed insight into the life-history and ecology of a Critically Endangered island pteropodid identifying aspects of growth, maturation and the timing of critical reproductive events. I have identified important aspects of P. natalis' foraging behaviours and movements, and compiled the most complete list of the foraging resources used by the species. I have identified factors such as the slow rates of growth and maturation, potential foraging resource bottlenecks and male-biased sex ratios, all potential contributors to the species decline and should be considered in the management of the species and its habitat. Overall, the results of my research provide vital information and guidance to assist in the recovery of this species and the management of island species more generally.

Date of Award	2019
Original language	English