Booby Island is an uninhabited islet in Saint Kitts and Nevis. It is found in The Narrows, the channel between the islands of Saint Kitts and Nevis, where Booby Island is an approximate midpoint between the islands. Booby Island is cone-shaped, consisting of a steep hill and a rocky shoreline. The island is of interest to ornithology for its bird population, and it is designated as an Important Bird Area by BirdLife International.
Booby Island is a cone-shaped islet. It is approximately 1ha in area, with a width of about 38m (125feet) across. Its peak reaches a height of 126feet. The island lies in The Narrows, the channel between the islands of Nevis and St. Kitts, where it is an approximate midpoint between the two islands. It is one of two islands in The Narrows, along with Cow Rock, which measures only 2m (07feet) across.
The island is a steep hill with rocky outcroppings and a shoreline is made up of large rocks. A sample of basaltic andesite from Booby Island's southeast coast was predominantly composed of, by weight: silicon dioxide (56.41%), aluminium oxide (17.91%), ferric oxide (8.90%), calcium oxide (6.68%), sodium oxide (3.51%), and magnesium oxide (2.30%).
Booby Island is a major seabird nesting site in St. Kitts and Nevis. BirdLife International designated Booby Island as an Important Bird Area, which includes the entire island and seas up to one kilometre away, for which it has the identification code KN003. Eight species of seabird are found on Booby Island, where nesting season begins in April or May and ends between August and October. The island's brown pelicans are colloquially referred to as boobies.
A 1997 survey of the island's seabird population found that it hosted 400 to 600 nesting pairs. The most common were sooty terns, followed by bridled terns, laughing gulls, roseate terns, and brown noddies. Red-billed tropicbirds can also be found on Booby Island. All of these species are rare to St. Kitts and Nevis and are not found in any part of the country besides Booby Island. In 2008, it was estimated that there were approximately 425 nesting pairs. The seabird population is fragile, as eggs are easily accessible and chasing birds from their nests causes the eggs to quickly overheat. 15 pairs of roseate terns were identified in 1997, but only two were found the following year.
Booby Island is not subject to any special environmental protections. The interior of the island contains dense populations of brushy plants. No mammal populations were discovered on the island in a 2004 survey.
Booby Island is uninhabited. It is controlled by the government of Saint Kitts and Nevis and is not privately owned. The island's geography makes human access challenging, as boats cannot approach and visitors must swim over the rocky shoreline. Fishermen sometimes collect the eggs of laughing gulls and other species of bird, which may have a negative effect on the bird population. Over time, the fishing community of Newcastle has shifted its fishing grounds from the coasts of Nevis and St. Kitts to the coast of Booby Island, to save on fuel use and to avoid overfished areas. Shark attacks are rare, but one incident was documented in 2021 in which an American student was bit by a tiger shark while swimming off the island's coast, resulting in amputation above the knee.