Christmas Island Biodiversity Monitoring Program: December 2003 to April 2007 Report to the Department of Finance and Deregulation, from the Director of National Parks September 2008 2 Christmas Island Biodiversity Monitoring Program Project Contributions Project coordination: D.J. James; Field survey: D.J. James, K. Retallick; Data management, GIS: D.J. James, K. Retallick; Analyses and reporting: D.J. James Citation This document can be cited as: Christmas Island Biodiversity Monitoring Program: December 2003 to April 2007. Report to the Department of Finance and Deregulation from the Director of National Parks © Director of National Parks 2008 Christmas Island Biodiversity Monitoring Program 3 Contents EXECUTIVE SUMMARY ........................................................................................................................7 1. INTRODUCTION.................................................................................................................................9 1.1 Checklist of flora and fauna of Christmas Island.....................................................................9 1.2 Christmas Island biodiversity inventory database.................................................................10 2. CHRISTMAS ISLAND PIPISTRELLE ........................................................................................11 2.1 Summary of the results .........................................................................................................11 2.2 Research and monitoring methods .......................................................................................12 2.3 Detailed survey and monitoring results.................................................................................13 2.4 Assessment of threats...........................................................................................................24 3. CHRISTMAS ISLAND FLYING FOX..........................................................................................30 3.1 Summary of the results .........................................................................................................30 3.2 Distribution and abundance ..................................................................................................31 3.3 Biology...................................................................................................................................39 3.4 Ecosystem services provided by flying fox ...........................................................................48 3.5 Assessment of threats...........................................................................................................51 3.6 Legal protection.....................................................................................................................56 4. LAND BIRDS ..............................................................................................................................57 4.1 Summary of results ...............................................................................................................57 4.2 Christmas Island goshawk ....................................................................................................58 4.3 Christmas Island hawk-owl ...................................................................................................59 4.4 Island thrush..........................................................................................................................59 5. SEABIRDS..................................................................................................................................61 5.1 Abbott’s booby.......................................................................................................................61 5.2 Christmas Island frigatebird ..................................................................................................63 5.3 Red-tailed tropicbird ..............................................................................................................64 5.4 Seabird banding ....................................................................................................................65 6. REPTILES...................................................................................................................................66 6.1 Summary of results ...............................................................................................................66 6.2 Forest skink...........................................................................................................................67 6.3 Blue-tailed skink ....................................................................................................................68 6.4 Coastal skink.........................................................................................................................71 6.5 Giant gecko ...........................................................................................................................71 6.6 Christmas Island blind snake ................................................................................................72 7. LAND CRABS.............................................................................................................................75 7.1 Summary of results ...............................................................................................................75 7.2 Population size and structure: red crabs...............................................................................76 7.3 Population size and structure: robber crabs .........................................................................80 7.4 Road mortality of crabs in 2004 to 2006 ...............................................................................82 7.5 Road mortality of crabs during the 2005–06 migration .........................................................84 8. OTHER INVERTEBRATES ........................................................................................................89 8.1 Invertebrate collection ...........................................................................................................89 8.2 Snails.....................................................................................................................................90 8.3 Spiders ..................................................................................................................................90 9. INTRODUCED SPECIES............................................................................................................91 9.1 Summary of results ...............................................................................................................91 9.2 Giant African land snail .........................................................................................................91 4 Christmas Island Biodiversity Monitoring Program 9.3 Yellow crazy ant ....................................................................................................................91 9.4 Giant centipede .....................................................................................................................92 9.5 Grass skink............................................................................................................................93 9.6 Barking house gecko.............................................................................................................94 9.7 Asian house gecko................................................................................................................95 9.8 Flowerpot blind snake ...........................................................................................................95 9.9 Wolf snake.............................................................................................................................96 9.10 Rats .......................................................................................................................................99 9.11 Other species ............................................................................................................................99 10. IMPACTS OF THE IRPC ON BIODIVERSITY .............................................................................101 10.1 Construction phase .............................................................................................................101 10.2 Ongoing operation of the IRPC...........................................................................................102 10.3 Recommendations for the IRPC .........................................................................................102 11. CONCLUSIONS........................................................................................................................104 11.1 Future work priorities...............................................................................................................106 REFERENCES....................................................................................................................................108 ACKNOWLEDGMENTS.....................................................................................................................117 APPENDIX A: PIPISTRELLE RESEARCH AND MONITORING......................................................118 APPENDIX B: FOREST BIRD SURVEY METHODS ........................................................................123 APPENDIX C: FLYING FOX SURVEY METHODS ...........................................................................125