A Bat’s End. The Christmas Island Pipistrelle and Extinction in Australia

Extract

The loss of any species is irreparable because its role in the ecosystem has ceased to exist. This book narrates the loss of the Christmas Island bat (Pipistrellus murrayi), which was declared extinct in 2009. In the first half of the book, the author describes the research, monitoring, management, and socioeconomic policies that led to the extinction of the Christmas Island bat. The book explains how islands are more susceptible to species loss than continental areas because co-adaptation leads to a high degree of susceptibility to anthropogenic changes to the environment, especially when there is low genetic variability associated with a restricted population size. The historical setting of the island is presented, with an emphasis on the discovery of the island by John Murray, for whom the species was named. Christmas Island was a British settlement for the purpose of phosphate extraction, regulated by the British Phosphate Commission, until the island became part of Australia during the middle of last century. Once mining extraction was completed, there was an economic transformation towards agriculture and livestock. In a description of the biodiversity of the island, only two species of endemic bats are described, Pteropus natalis and Pi. murrayi. The decline of native fauna was initially reported during the beginning of last century, when British naturalists warned about the population declines and increasingly rare sightings of species such as Maclear rat (Rattus macleari) and the Christmas Island shrew (Crocidura trichura). These species went from hundreds of individual observations to rare sightings, mainly due to the introduction of exotic species of plants and animals. The ecological disaster on the island was already imminent, and the first actions to protect native species began in 1992, with the implementation of regulations and the creation of special protection areas. In 2002, a recovery plan for the Christmas Island bat was developed, but there was a lack of financial support for its implementation. By 2017, the two species of endemic bats were already critically endangered but there was no action for protection by the government. The book then describes past and recent research on Pi. murrayi. The first scientific report was published in 1887 by J. J. Lister and little attention was paid to the species until 1932, when the zoologist M. W. F. Tweedie, a researcher at the National University of Singapore, made a collecting expedition to the island. Subsequent reports, subsidized by the government of Australia for the study of the species, showed the taxonomic validity of this insectivorous bat, corroborated by morphological and genetic analyses. During the 1990s, Lindy Lumsden postulated that although the bat was widely distributed on the island, its population numbers were too low to be sustainable, and the species was additionally threatened by its habitat interdependence with native plant species, which were threatened by human impacts. By 2001, the species was listed as being at risk. With a logarithmic decrease in population size due to multiple factors such as changes to the landscape and the introduction of exotic predators, a recovery and breeding program was approved in 2009. However, the efforts were too late and there were no longer discoveries of the bat species on the island.