Distribution and Population dynamics of the Galapagos-albatross

Albatrosses are majestic sea birds. With a wingspan of up to 3,5m the Wandering Albatross is one of the most spectacular sights for ocean travellers. The somewhat smaller Galapagos albatross (Phoebastria irrorata) is the only albatross within the tropics and nests almost uniquely on the island of Española in the Galapagos Islands. Its population is about 12'000 pairs. The nesting places of the Galapagos albatrosses are protected by the National Park personnel, but the albatross population is affected by tourism and by introduced avian diseases. In addition a new threat to the survival of the albatrosses has arrived in the form of illegal fishing of which the albatrosses are indirectly the victims.

Since 1966, more than 8'000 albatross of Española have been ringed. In order to determine the present demographic data, which is important for the protection of the species, the project was restarted in November 2001, at the beginning of the albatros breeding season.

Aims of the project

• to determine the distribution and population dynamics of the Galapagos-albatrosses.
• to define the fishing zones of the albatrosses in the archipelago and determine the effect of human activities on the population dynamics.

First results are:

Two important nesting areas on Española

The albatrosses nest mainly in two areas of Española: Punta Suárez in the West of the island, also a tourist area, and Punta Cevallos, in the East. These two areas were the object of observation twice a year and were surveyed during in situ expeditions from 10th to13th July 2001, from 7th to 9th December 2001 and 3rd to 7th June 2002.

Breeding statistics for June 2002 and July 2001

The number of adults, nests, eggs, chicks and abandoned eggs is given in Table 1.

The results show that Punta Cevallos offers more nesting zones than Punta Suárez.

The results of December 2002 (Table 2) show less adults, no eggs, but many chicks. The date is also the near the end of the 2001 breeding period.

Long life, low rate of reproduction

During the project, 800 albatrosses, including 538 adults and 262 chicks, were ringed. During this new ringing, birds were found which had already been ringed . Of the 136 birds taken in June 2002, 26 had a readable marking; 6 of them had been ringed as chicks, and that allowed a precise determination of their age. The youngest ones were 13 years old and the two oldest, which were ringed in December 1966, were more than 36 years old. This is the first proof of the longevity of the Galápagos albatros.

The study also indicates a very low reproduction rate: a couple which lasts for 30 years, has only two chicks. During these years, the female lays about 25 eggs; with a survival of only 8%, the successful breeding rate is therefore extremely low. A population where the reproduction rate is so low and the survival rate of the chicks so unsure, increases very slowly, if it increases at all. The time needed to double such a population could be several hundred years, as it is, for example, with the Galápagos tortoise.

Chicks ready for flying have better survival chances

If the low survival rate of the Galapagos albatross is also reduced by activities such as industrial fishing that destroys the food supply or where the fishing lines drown the birds, their future is at risk. In general it is said that a chick ready for flying has better chances of survival. The decrease of the mortality rate of the chicks is therefore the main aim of the project.

To know more about the distribution of the Galapagos albatross, a study of the fish-rich waters in the South-east will be made in December 2002. The data collected will give precious information on the role these regions have for the albatross and therefore for the conservation of this unique species.

Our association supports this project with a sum of CHF 22'200 at present.