This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
The Three Brothers islands on the Great Chagos Bank is a magical place filled with more birds than you would think could fit on the tiny islands. On Middle Brother, a beautiful island with its own large lagoon, over thirty thousand sooty terns were nesting, as well as noddy terns and red-footed boobies.
On North Brother, a more challenging island to land on, thousands of wedge-tailed shearwaters had nesting burrows in every suitable space on the ground that they could - except for that occupied by the ground-nesting brown boobies.
These illustrate how important unspoilt islands are for these birds, as, being ground nesters, they would be completely vulnerable to rats, cats, dogs and of course man in inhabited areas. The islands also illustrate another point raised by the expedition ornithologist Pete Carr, that Important Bird Areas (IBAs), of which Chagos has ten, should encompass not single islands but groups of islands.
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South Brother normally has ten thousand pairs of nesting Sooty Terns, but this year they all seem to have moved to Middle Brother to nest. Therefore South Brother has no significant numbers of sooty terns nesting on it at the moment. It would still retain its IBA status, but if the group of islets collectively were one ‘IBA cluster’ then that would make more sense over the years and would cater for such movements.
Previously in this series:
Conserving Chagos: Science Expedition to World’s Largest “Ocean Park”
Conserving Chagos: Starting Out
Conserving Chagos: Last Day around Diego Garcia
Conserving Chagos: Salomons Atoll
Conserving Chagos: Stormy weather
Conserving Chagos: Nelsons Island
Conserving Chagos: Peros Banhos atoll
Conserving Chagos: Thoughts from the Diving Officer