Coringa-Herald National Nature Reserve seabird monitoring
Barry Baker, Mark Holdsworth, Luke Finley & Mike Double
Department of the Environment, Water, Heritage and the Arts, February 2008
Australias Coral Sea Island Territory contains extensive seabird rookeries of great significance to the ecological balance of the Coral Sea region, with thirteen seabird species recorded breeding in the area. While some of these species (such as the red-footed booby (Sula sula), least frigatebird (Fregata ariel), great frigatebird (Fregata minor) and red-tailed tropicbird (Phaethon rubricauda) have an extensive distribution outside of Australian waters, they are uncommon within Australia. The islands and cays of the Coral Sea are important in that they contain a significant proportion of the regions breeding populations.
Coringa-Herald National Nature Reserve, which covers approximately 8860 sq km, was proclaimed as a National Nature Reserve under Commonwealth legislation on 16 August 1982. The reserve contains six sand cays and islets with fringing reef systems that have developed on the shallow shelves of the Coral Sea Plateau. A major reason for proclaiming these reserves was to protect the seabirds that breed in the region (ANPWS 1989).
We have been monitoring seabirds in the Coringa-Herald National Nature Reserve since 1992. The monitoring program established is centred on one islet, North East Herald Cay (NEH), with visits to other islets, principally South West Herald Cay (SWH), carried out as time permits. Data are principally collected during one visit to NEH each year, which is timed to coincide with periods of peak breeding activity for three species with important breeding populations in the region red-footed booby, least frigatebird and greater frigatebird. Data collection has relied on a design and estimation methodology that is scientifically rigorous and developed specifically to monitor seabirds in the Coral Sea. An understanding of the seabirds in the region has been enhanced by the accumulation of long-term data sets there are now 16-year and 5-year data sets available for NEH and SWH, respectively.
A patrol in August 2007 was undertaken to conduct an annual count of the nesting seabird populations on NEH and SWH. Counts of nesting birds in the three major habitats on NEH were completed during this patrol. SWH was also briefly visited where a count of nesting seabirds in Argusia shrubland was undertaken. Data collected on the patrol were incorporated with all data collected since 1992 and subsequently analysed for long-term trends. These long-term trends are reported upon in this report.