2000 Miles from Anywhere...: The Great Tristan Albatross Count

One of the many jobs during the change-over period, and perhaps the most important, is the round-island count of Tristan Albatross fledglings. These counts are vitally important for this Critically Endangered species, endemic to the Tristan Group of islands. They are also an opportunity for the new team (that’s us!) to learn our way around the island.

A young Tristan Albatross growing fast....and a bird we counted! (© David Kinchin-Smith)

So firstly, some background about Tristan Albatrosses (or Gonys, as they are referred to by the Tristanians). Gough Island is home to 99% of the world population, with a pair occasionally nesting on Inaccessible Island in the Tristan Group. They previously nested on Tristan but became extinct from the island by 1900. Between 1,000 and 2,500 pairs nest on Gough each year, but on average only about a quarter of chicks survive until fledging; in 2014 this was less than 10% (RSPB – Gough Island Restoration Programme). This is well below the productivity required to sustain the population, let alone increase it. The main cause of the mortality on Gough is the introduced House Mice, which feed on the young, defenceless, downy chicks. This is an annual reminder of why a successful mouse eradication is essential to prevent the dramatic decline of this, and many other spectacular bird species that Gough is home to. If these mice aren’t wiped out from the island, the extinction of the majestic Gony is an eventual certainty (please read: http://www.rspb.org.uk/whatwedo/projects/details.aspx?id=419512).

Tristan Albatross adult with young chick (© Derren Fox)

As for our counts.....Gough is not a huge island, being only 13km long and 5 km wide, but the vegetation and mountainous terrain make it very difficult to walk across. With ever-changing South Atlantic weather, fog can quickly descend over the higher ground making navigation a bit of a nightmare. Tristan Albatrosses only nest above 400m on Gough, and dense fog meant that the first day of our count was a bit of a write-off. But days 2 and 3 brought clear weather and perfect counting conditions allowing us to cover a large proportion of the island. Last week we returned to the North end of the island to finish off the areas that were fog-bound previously. Our counts revealed a similar story to the annual average, but a long way from the lows of 2014 which was a relief.

Gough Island with our count route marked in red (© Gough Island archive)

We will be doing another round-island count towards the end of January 2017. This time it will be to count all incubating birds before repeating it again in September (for the Gough 63 team) to see which pairs successfully fledged a chick. With eggs laid in January and chicks not departing until near the end of the year, adults only breed every other year in order to recover from a long and challenging breeding season.

David

Reference.

Ryan, P. et al. (2007) Field Guide to the Animals and Plants of Tristan da Cunha and Gough Island