INVESTIGATION OF THREATS TO THE CHRISTMAS ISLAND PIPISTRELLE A Report to the Department of the Environment and Water Resources Prepared by: Lindy Lumsden, Martin Schulz, Raquel Ashton and David Middleton Arthur Rylah Institute for Environmental Research Department of Sustainability and Environment 123 Brown Street, Heidelberg VIC 3084 March 2007 Arthur Rylah Institute Flora, Fauna & Freshwater Research Title: Investigation of threats to the Christmas Island Pipistrelle. Produced by: Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, 123 Brown Street, Heidelberg, Victoria, Australia 3084 ABN 9071905 2204 Date: March 2007 This document may be cited as: Lumsden, L., Schulz, M., Ashton, R. and Middleton, D. (2007). Investigation of threats to the Christmas Island Pipistrelle. A report to the Department of the Environment and Water Resources. Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, Heidelberg, Victoria. Cover photo: The Christmas Island Pipistrelle Pipistrellus murrayi (Lindy Lumsden) Copyright © Department of Sustainability and Environment, Victoria General disclaimer This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. 2 Table of Contents Table of Contents ........................................................................................................................2 List of Tables................................................................................................................................5 List of Figures..............................................................................................................................5 List of Plates.................................................................................................................................5 Acknowledgments........................................................................................................................7 Executive summary.....................................................................................................................8 The decline of the Christmas Island Pipistrelle.........................................................................8 Wet season 2005/06 study and new perspectives on the causes of decline ..............................8 The future ................................................................................................................................10 Introduction ...............................................................................................................................11 Methods......................................................................................................................................14 Duration and timing of study ..................................................................................................14 Detector sampling ...................................................................................................................14 Trapping ..................................................................................................................................14 Collection of biological samples to assess health status .........................................................16 Location of roost sites .............................................................................................................18 Observations of roost trees using infra-red cameras ...............................................................20 Observations on other species.................................................................................................22 Results ........................................................................................................................................23 Detector sampling ...................................................................................................................23 Number of individuals caught.................................................................................................23 Disease investigation...............................................................................................................26 Roost sites ...............................................................................................................................27 Availability and longevity of maternity roosts........................................................................34 Colony size and roosting behaviour........................................................................................39 Emergence times and investigation of daytime flight.............................................................40 Observations of roost trees using infra-red cameras ...............................................................42 Nankeen Kestrel observations.................................................................................................44 Feral Cat sightings...................................................................................................................46 Common Wolf Snake observations.........................................................................................47 Other observations...................................................................................................................48 Discussion...................................................................................................................................50 Key findings of the study ........................................................................................................50 Clarification of current distribution.....................................................................................50 Estimation of the size of the remaining population.............................................................50 Confirmation of breeding status..........................................................................................51 Location of maternity roosts ...............................................................................................51 Identification of further threats ...........................................................................................51 Investigations of potential predators ...................................................................................52 Investigation of disease .......................................................................................................52 Nomination for listing the species as ‘Critically Endangered’ ...........................................53 3 Threat analysis.........................................................................................................................53 Predation or disturbance by the Common Wolf Snake Lycodon aulicus capucinus ..........54 Predation and/or disturbance by the Giant Centipede Scolopendra morsitans...................55 Predation and/or disturbance by the Yellow Crazy Ant Anoplolepis gracilipes.................57 Predation by the Nankeen Kestrel Falco cenchroides ........................................................58 Predation by the introduced Black Rat Rattus rattus ..........................................................59 Predation by the Feral Cat Felis catus ................................................................................59 Predation by endemic predators ..........................................................................................60 Disturbance to roost sites from Giant African Snails Achatina fulica ................................60 Habitat loss..........................................................................................................................61 Habitat alteration.................................................................................................................61 Loss of roost sites................................................................................................................61 Prey availability...................................................................................................................62 Climatic conditions .............................................................................................................63 Vehicle-related mortality.....................................................................................................63 Disease ................................................................................................................................63 Decreasing population size..................................................................................................64 Options for future management...............................................................................................64 Captive breeding .................................................................................................................64 On-ground roost management.............................................................................................66 Predator control...................................................................................................................67 Further investigations to determine cause of decline..........................................................70