Description

Mixed feeding flocks of this species offshore along with Red-footed Booby and Lesser Noddy are a great natural spectacle, often seen on boating trips off Diego Garcia. Huge shoals of small fish are driven to the surface by underwater predators where several hundred birds flock to feast on them: the waters are explosive with jumping fish and diving birds.

Identification Guide: Being brown all year and having a wedge-shaped tail means Brown Noddy is a straightforward species to identify to genus, though some care is needed to separate it from Lesser Noddy that also occurs in BIOT. Brown Noddy is a warm chocolate-brown with a duller greyer head patch. It is also larger, looking noticeably bulkier in flight, particularly the chest and with longer wings and bigger bill.

Status and Distribution: A common resident: it still breeds individually in trees on most islands of the Territory. However, the large colonies that once occurred have not been recorded in the Territory since 1996. The decline in breeding numbers for Brown Noddy has not been attributable to any cause and is of great concern. In 1975 during a survey of the Great Chagos Bank islands, it was noted as the most numerous species on all the islands except Resurgent and Eagle, neither of which suit Brown Noddy as breeding islands due to the rocky exposed nature of the former and rats being present on the latter. During this survey, Nelsons Island held 16,600 pairs, Danger Island 12,500 pairs, Sea Cow 11,500 pairs, South Brother 7,400 pairs and smaller numbers on Middle and North Brother. In 1996, these islands still held colonies numbering low thousands, though overall breeding numbers had declined. By 2006, the numbers had catastrophically declined. Throughout quarterly surveys between October 2008 and October 2010, that visited all of the known breeding islands, no breeding colonies of this species were located. The reason for this apparent decline is unknown. In fact, so little is known of its breeding strategy in BIOT that it could simply be that protracted periods of non-breeding are normal. It is still a common species throughout the Territory, possibly due to longevity, nowhere more so than Diego Garcia, where it very evident in the coconut trees of Downtown.