THE STATUS OF SEABIRDS AND SHOREBIRDS AT ASHMORE REEF, CARTIER ISLAND & BROWSE ISLAND MONITORING PROGRAM FOR THE MONTARA WELL RELEASE PRE-IMPACT ASSESSMENT AND FIRST POST-IMPACT FIELD SURVEY Rohan H. Clarke Australian Centre for Biodiversity School of Biological Science, Monash University, Clayton, Vic. Final report: June 2010 Figure 1 Mixed colony of seabirds, predominantly Brown Boobies and Common Noddies, East Island, Ashmore Reef, April 2010 Recommended citation: Clarke, R.H. 2010. The Status of Seabirds and Shorebirds at Ashmore Reef and Cartier and Browse Islands: Monitoring program for the Montara Well release - Pre-impact Assessment and First Post-impact Field Survey. Prepared on behalf of PTTEP Australasia and the Department of the Environment, Water, Heritage and the Arts, Australia (now the Department of Sustainability, Environment, Water, Population and Communities). Seabirds and Shorebirds at Ashmore Reef, Cartier Reef and Browse Island ii TABLE OF CONTENTS Introduction ............................................................................................................................. 1 Study Objectives .................................................................................................................... 5 Approach and Methods .......................................................................................................... 6 Pre-impact Assessment......................................................................................................... 6 Collation, analysis & review of existing data ................................................................................... 6 Initial Field Survey.................................................................................................................. 7 Detailed census methods................................................................................................................ 7 Breeding seabirds ........................................................................................................................... 7 Vegetation condition........................................................................................................................ 8 Data collection and management.................................................................................................... 9 Results...................................................................................................................................... 9 Ashmore Reef ........................................................................................................................ 9 Terrestrial environments.................................................................................................................. 9 Seabirds ........................................................................................................................................ 15 Individual Seabird Species Accounts .................................................................................. 21 Wedge-tailed Shearwater.............................................................................................................. 21 Red-tailed Tropicbird..................................................................................................................... 22 White-tailed Tropicbird .................................................................................................................. 23 Masked Booby............................................................................................................................... 24 Red-footed Booby ......................................................................................................................... 25 Brown Booby ................................................................................................................................. 26 Great Frigatebird ........................................................................................................................... 28 Lesser Frigatebird ......................................................................................................................... 29 Crested Tern ................................................................................................................................. 31 Lesser Crested Tern...................................................................................................................... 32 Roseate Tern................................................................................................................................. 33 Bridled Tern................................................................................................................................... 33 Sooty Tern..................................................................................................................................... 35 Common Noddy ............................................................................................................................ 36 Black Noddy .................................................................................................................................. 37 Lesser Noddy ................................................................................................................................39 Egrets and Herons ........................................................................................................................ 41 Shorebirds............................................................................................................................ 42 April 2010 counts........................................................................................................................... 43 Previous records ........................................................................................................................... 44 Stop-over or non-breeding site?.................................................................................................... 44 Cartier Island........................................................................................................................ 48 Terrestrial environments................................................................................................................ 48 Avifauna ........................................................................................................................................ 48 Browse Island ...................................................................................................................... 49 Terrestrial environments................................................................................................................ 49 Avifauna ........................................................................................................................................ 50 Oil Contamination in April 2010 ........................................................................................... 52 Conclusions and Future Directions.................................................................................... 52 Ongoing Post-impact Assessment ...................................................................................... 52 Twice-annual ground assessments............................................................................................... 52 Statistical Analyses.............................................................................................................. 54 Control datasets ............................................................................................................................ 62 Reserve Systems on the Sahul Shelf: Significant Impact & Assessment Criteria.............. 63 Conclusions.......................................................................................................................... 65 References ............................................................................................................................. 66 Appendix A............................................................................................................................. 70 Appendix B............................................................................................................................. 72 Appendix C............................................................................................................................. 73 Seabirds and Shorebirds at Ashmore Reef, Cartier Reef and Browse Island iii LIST OF TABLES Table 1 Breeding distribution of seabirds and herons on the three vegetated islands of 17 Ashmore Reef, Australia Table 2 Count of tropicbirds on West Island, Ashmore Reef during 15 visits between 18 October 1998 and April 2010 Table 3 The maximum count of seabirds obtained during 48 visits between 1979 and 18 1998 and counts of seabirds during 13 visits between Jan 2002 and April 2010 at Middle Island, Ashmore Reef Table 4 The maximum count of seabirds obtained during 51 visits between 1979 and 19 1998 and counts of seabirds during 8 visits between Jan 2002 and April 2010 at East Island, Ashmore Reef Table 5 Count of Eastern Reef Egrets on West Island, Ashmore Reef during 16 visits 19 between Oct 1998 and October 2009 Table 6 Maximum counts of shorebirds recorded at Ashmore Reef between 1979 and 44 2010 Table 7 The maximum count of shorebirds obtained during 69 visits to Ashmore Reef 45 between 1979 and 1998 and data from four complete counts of shorebirds at Ashmore Reef between January 2002 and April 2010 Table 8 Count of shorebirds