Sooty Tern travels


17-June-2013

The 2012 team of Christine, Chris, Audrey and Camille

In the 1930s and 1940s, vast numbers were collected each year, leading some colonies to become extinct and others to dwindle in numbers. This led to concerns over the effects of over-harvesting of eggs and to a preliminary assessment of the problem by two British scientists in 1955.

The vast majority of “birds’ eggs” are eggs of the Sooty Tern (Golet) and in 1971, Chris Feare, a scientist from UK, began a study on Bird Island, funded by the British government, in order to discover how many eggs could be taken each year without damaging the bird population. That three-year study has resulted in a life-long fascination for Chris, who has uncovered over the ensuing 40 years a wealth of information about Sooty Tern lifestyles on many Seychelles islands. In addition to Bird Island, the environment department, Islands Development Company, Nature Seychelles, owners and managers of other islands and many volunteers have been involved from time to time. In addition to Bird Island, large colonies are found on Aride, Desnoeufs, Farquhar and Cosmoledo. But at the end of each breeding season, the vast number of birds that nest on Seychelles islands just disappear and where they go was a complete mystery.

Recently, tiny tracking devices suitable for small birds have been developed and in 2011, with funds from the Percy Sladen Fund in UK and donations from many of Chris’s friends there, and with a contribution from Robert Gaines-Cooper in Seychelles, help from Matthieu Le Corre from the university of Reunion and great support from the owners of Bird Island, weSooty tern with geolocators attached to a ring on its right leg were able to begin to study their off-season journeys. With help from Christine Larose and Chris’s friends Ron and Bozena Summers from UK, we attached geolocators to 60 Sooty Terns on Bird Island. In 2012 Chris and Christine, this time accompanied by two colleagues from the University of Reunion, Audrey Jaeger and Camille Lebarbenchon, managed to recover six of these birds.

Their tracks show that they are extreme ocean wanderers. After the breeding season they leave Seychelles waters and head north-east. Most spent the north-west monsoon period in the north-eastern Arabian Sea and also travelled round the south of India and Sri Lanka. Two spent most of their time in the Bay of Bengal and another visited the seas south of Sumatra in Indonesia.

In March, birds that had been feeding in the Arabian Sea migrated south to feed in the central equatorial Indian Ocean, before travelling west towards Seychelles in May, while one of the birds that had been feeding in the Bay of Bengal sped back to Seychelles waters in May. Having reached Seychelles, the birds then went south-east for a short time before returning to Seychelles to breed in late May - June

These Seychelles birds are truly international travellers. We hope that further studies will enable us to see whether the places where they go have particular oceanic characteristics, whether they overlap with industrial fisheries and whether we can identify other at-sea threats to what we tend to regard, clearly erroneously, as “our” birds.

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