Brown booby

How it lives

Brown boobies nest on the ground in colonies, on islands, cays and atolls, from sea level to about 15 m. Pairs usually lay two eggs but raise only one chick. Incubation takes about 43 days and chicks fledge after roughly 95 to 120 days, then are fed for several more weeks. They often keep the same partner and first breed at about age four. The longest recorded life is 27.2 years.

Where it goes

Brown boobies fly out from their nesting colony to feed at sea and need prey within about 50 km of it. Young birds leave the colony after fledging and may not return for three or more years. The species ranges across tropical oceans between about 30°N and 30°S. In West Africa, Ile Alcatraz off Guinea holds the only known breeding colony between Cape Verde and Sao Tome and Principe.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

Estimates of the world population differ: about 200,000 birds in Birds of the World and about 500,000 in the Audubon guide. IUCN lists it as Least Concern (2018). In 2024 the eastern Pacific birds were split off as a separate species, the Cocos booby, so Atlantic birds are not affected by that change. Australia held an estimated 59,940 to 73,900 breeding pairs in 1996 to 1997. At Ile Alcatraz in Guinea, a 1988 count gave about 3,000 pairs. Threats include introduced predators such as cats and rats, disturbance at nests, and El Nino years that cut food supply.