GREAT BARRIER REEF
// Outlook Report 2014
In terms of variety of species, numbers of breeding adults and conservation significance, the four most important seabird areas in the Great Barrier Reef are Raine Island225, Michaelmas Cay226, the islands of the Capricorn–Bunker Group227 and the cays of the Swain Reefs.228 While there is regular monitoring at many of these sites229, long-term trend information is only available for a small number of islands, such as Michaelmas Cay, and for only a limited number of species. Fourteen seabird species regularly breed at Raine Island in the Region’s north making it one of the most important seabird rookeries in the Region.26 Information presented in the Outlook Report 2009 suggested there were declines in many seabird species at Raine Island; however, a review of the survey method and recent survey data indicate declines may not be evident in all species.230 Surveys of Raine Island conducted in July 2013 recorded the highest numbers of breeding pairs of lesser frigatebirds since surveys began in 1979.230 Monitoring at Michaelmas Cay shows wide annual variation in seabird breeding numbers. It suggests there have been no significant long-term trends in the island’s breeding populations of common noddies, crested terns and sooty terns over the past 30 years (Figure 2.13). Monitoring data collected from islands in the Capricorn– Bunker Group indicate the wedge-tailed shearwater population may have declined by nearly 40 per cent over the past 15 years while black noddy numbers have remained relatively steady.232 Despite a ten-year gap in the monitoring effort and limited recent surveys, these trends are cause for concern in the context of associated declines in New Caledonia232 and likely changes in key supporting resources and environmental conditions232 as a result of factors such as climate change233,234. The population of the brown booby nesting in the Swain Reefs may have declined between the 1980s and the 1990s as vegetation was lost from key breeding cays, principally from a series of cyclones in the area, and the habitat has only partially recovered.228,235 Gannet Cay (named for the boobies breeding on it) was a very important breeding island in the Swain Reefs and a sharp decline in breeding pairs was observed following almost complete vegetation loss in the mid-1980s228 (Figure 2.14).
There are declines in some seabird breeding areas and changes in key supporting resources.
Figure 2.13 Mean number of observed seabird breeding pairs, Michaelmas Cay, 1984–2012
The number of seabirds breeding on Michaelmas Cay varies from year to year. There are no clear long-term trends. The data represents the average number of breeding pairs recorded during field observations of three seabird species: the common noddy, sooty tern and crested tern. Source: Queensland Coastal Bird Atlas 2014 231
At least 41 species of shorebirds are known to inhabit the Great Barrier Reef. 236 A number of sites are known to provide important habitats for shorebirds, including the islands off False Orford Ness in Cape York, Pelican Island and nearby islands, Cairns foreshore, Cape Bowling Green, Burdekin River delta, Pioneer River to McEwan’s Beach and Notch Point near Mackay, Shoalwater Bay and Broad Sound. 237 There are no population estimates for the Region’s shorebirds. Australia-wide declines of between 70 and 80 per cent have been recorded in the past 24 years238, including populations that migrate through the Region.
Figure 2.14 Number of observed brown booby breeding pairs, Gannet Cay, 1980–2013
The data represents the number of breeding pairs recorded during field observations. The number of brown boobies breeding at Gannet Cay in the Swain Reefs declined following the almost complete loss of vegetation in the mid-1980s. Source: Queensland Coastal Bird Atlas 2014231