SummaryWe report the results of a survey of breeding Greater Frigatebird Fregata minor and Lesser Frigatebird F. ariel on Aldabra Atoll, a UNESCO World Heritage site in the Seychelles archipelago, which hosts the largest breeding population of frigatebirds in the Indian Ocean. All four colonies across the atoll were surveyed in 2011 and 2012 by counting adults on nests and chicks, and calculating the number of fledged birds. The breeding population in 2011 consisted of approximately 4,400 pairs of Greater Frigatebird and 6,600 pairs of Lesser Frigatebird. This is a potential increase of at least 10% since the last comparable surveys in 1976/77 and 2000. However, 2012 populations were considerably less than in 2011, highlighting significant annual variation and the need for more data. We also report a new breeding colony on the island of Picard, which was last reported to host breeding frigatebirds a century ago. We outline recommendations for future frigatebird monitoring on Aldabra and elsewhere and revisions to tourist regulations resulting from the census.
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