New frigate bird survey ends on Aldabra
By Roland Duval, Seychelles Island Foundation, 17/02/11
A new frigatebird survey has been launched by SIF staff on Aldabra, which has the second largest frigatebird colony in the world and the largest in the Indian Ocean.
The survey in January and February was the fourth official census to be carried out on the atoll, following surveys by Diamond in 1967-68, Reville in 1976-77 and Burger and Betts in 2000. According to Reville (1983), there were approximately 4000 breeding pairs of greater frigatebird and 6000 pairs of lesser frigatebird on the atoll.
Numbers from the earlier surveys did not differ substantially but the species’ distribution around the atoll has changed over time. The biggest colony in the 1960s was at Middle Camp, while Camp Fregate hosted the largest colony in the 1970s. There also used to be a large colony at Passe Gionnet; however, now there are only a few birds nesting there. Last year the birds were recorded breeding at Grande Poche on Picard for the first time.
Because frigatebirds are highly sensitive to human disturbance when they are incubating eggs and brooding young chicks, the survey was scheduled for the beginning of the year (Jan–Feb), when larger chicks are on the nests and colonies are less sensitive.
The survey was carried out mainly by boat, keeping a safe distance (20-30m) and using binoculars, tally counters and GPS units so the nesting colonies could be mapped. The entire process was tide-dependent as are most activities on Aldabra. Some colonies, such as Camp Fregate on the east of Malabar, had to be monitored on very high spring tide while other places required neap tides. Middle Camp was surveyed from the boat at high tide with some parts surveyed on foot at low tide.
SIF volunteer Michal Šúr, who led the survey, said that the whole process went smoothly and the team of four managed to complete the work ahead of schedule. He added that the other team members were very committed and cooperative throughout and that it was an excellent team effort. Other members of the survey team were SIF rangers Nella Victor, Andy Gouffe and Stan Denis who was also the team’s boatman.
The survey so far indicates that the frigatebird populations of Aldabra have remained healthy. To obtain the most accurate estimate and complete the survey the same census will be repeated in a year because the frigate nesting cycle takes up to 500 days. SIF will therefore be able to report complete updated figures in 2012 so keep an eye on this space for more information.
Frigatebird survey photos
Left: The frigate survey team (L-R: Andy, Nella, Michal and Stan; photo by C. Quanz), Centre and right: frigatebird adults and chick (photos by M. Sur)