The Tristan Albatross Diomedea dabbenena was recently upgraded to Critically Endangered, due to the double blow of fishing mortality to birds at sea (mainly on long-lines) and House Mouse predation on chicks at its sole significant breeding site, Gough Island. The latter problem seems to be getting worse, with the 2008 chick production at an all time low. In the north of the island, where more than a quarter of all pairs breed, barely 1% of chicks survived to fledge!
The very low breeding success results in an aging population, with too few recruits entering the breeding population to balance the deaths of old birds. And old birds are dying. On 7 April 2009, a banded Tristan Albatross was found washed up on the beach near Gouritzmond in the southern Cape. This is the first confirmed record for the Indian Ocean coast of South Africa, although we know that Tristan Albatrosses occasionally reach Australia. The bird, a male, was first banded as G-12523 in February 1976 on Tafelkop, a small colony close to the weather station on Gough Island. At the time, he was just visiting, but must have been at least five years old, because Tristan Albatrosses only return to their colonies from this age. This means he was at least 38 years old when he died, making him the oldest Tristan Albatross on record. Quite why he died is unclear. Long-term studies of albatrosses show that as they age their breeding success decreases and their survival falls. But the fate of G-12523 is symptomatic of one of the many problems facing Tristan Albatrosses.
Coincidentally, another ringing recovery of a Tristan Albatross arrived on the same day as the one from Gouritzmond. At the start of 2007, John Cooper colour-banded all the adults breeding in Gonydale on Gough as the first year of a new study to monitor the demography of this threatened species. Although chicks from Gonydale have been ringed for more than 20 years, some unmarked adults were still present in 2007, including the female then ringed as J-15717/yellow B43. She probably was another old bird, hatched before regular ringing commenced in the early 1980s. She lost her chick in 2007 and again in 2008, presumably to mouse predation. After two arduous breeding attempts in a row, both of which failed, she apparently planned to take a year off, because neither she nor her mate (yellow B45) were recorded in the colony during early 2009. And we now know that she won’t be making an appearance in 2010, because on 10 January 2009 she was drowned on a long-line off southern Brazil.
Unfortunately, the sorry saga of J-15717 is typical of the sad lot faced by this species. Unless urgent steps are taken to both reduce long-line mortality at sea and eradicate mice from Gough Island, the future for the Tristan Albatross looks increasingly bleak.
News from Peter Ryan, FitzPatrick Institute, University of Cape Town, posted 21 April 2009