In collaboration with island-based researchers, we are investigating the migration routes and feeding areas of some of the pelagic seabirds breeding on the Norfolk Island group. In March 2008, we deployed geolocator tags on 8 wedge-tailed shearwaters (Puffinus pacificus). Three tags (see image at right, attached to the bird’s leg) were recovered in December 2008, when the birds returned to their burrows to breed after migration. The data now being processed should show, for the first time, where the shearwaters nesting on Norfolk Island spend the non-breeding season. We hope to recover the other tags in late 2009. The devices’ batteries provide enough power to record daily positions for over two years, so tags retrieved this year should contain information on two complete migrations.
Wedge-tailed shearwaters, known locally as “ghostbirds” because of their eery wailing calls at the nest, still breed on Norfolk Island itself. The population has, however, declined significantly since the 1980s, judging from descriptions of the size of the “rafts” of birds gathering offshore at dusk before returning to their burrows at and after dusk.
These shearwaters burrow in the soft volcanic soil on the cliffs and clifftops around the island but feral cats kill many adults and chicks.
Another tag was retrieved in November 2009. This had been deployed for nearly two years. Data retrieval and processing is under way, and we should soon know where the Norfolk Island wedge-tailed shearwaters spend their “off season”. Present information suggests that this species disperses northeastwards into the tropical Pacific, but exactly where the birds go is still unclear. Available banding data relate to the breeding season and show that the birds forage in the northwestern Tasman Sea.