116Wildlife Conservation Plan for Seabirds

116 Wildlife Conservation Plan for Seabirds

Clearance of nesting trees for fuel wood or land conversion has occurred on many islands throughout the range, reducing nesting sites available to the species (del Hoyo et al. 2019), but this does not appear to have had much impact on populations of this widespread species. Large numbers of birds of all ages have been harvested by Cocos-Malay people on Cocos (Keeling) Islands over the last century, and this has impacted this population. Protection of the population on North Keeling Island in more recent years has resulted in a much larger and more stable population, although it is still vulnerable to cyclones. An unquantified level of hunting is likely to take place in numerous south-east Asian and small Pacific colonies. However, this does not seem to be significantly affecting the population nesting there (Baker et al. 2004).

 Implement best practice quarantine measures at breeding colonies to reduce the risk of any invasive species (re)establishing on islands

Photograph of a Red-footed Booby

Wildlife Conservation Plan for Seabirds 117

Brown Booby (Sula leucogaster)

TABLE Species information for the Brown Booby (Sula leucogaster)

The Brown Booby (Sula leucogaster) is a medium sized, sleek looking dark-coloured booby with sharply demarcated brown and white underparts. The Brown Booby can be found throughout the pantropical oceans with few exceptions. Breeding sites include the Caribbean, the Atlantic coasts of Brazil and Africa, oceanic islands off Madagascar, the Red Sea, northern Australia, many oceanic islands in the western and central Pacific, as well as off the coast of Mexico and Peru. Breeding is seasonal in some areas, but elsewhere it breeds opportunistically or more or less continuously. Nests are built on the ground in the midst of vegetation on rocky islands or coral atolls. Individuals form colonies that are usually smaller than those of other Sula species (del Hoyo et al. 1992). This species is strictly marine, generally feeding on inshore waters. Its diet is comprised mainly of flying-fish and squid, but also some halfbeak, mullet and anchovy. Prey is usually caught by plunge-diving and it can also snatch prey off the surface of water. Kleptoparasitism has been observed, mostly by females.

The global population is estimated to number > 200,000 individuals (del Hoyo et al. 1992). Globally, the population is suspected to be in decline owing to disturbance and unsustainable levels of exploitation. Numerus breeding locations occur on offshore islands in the Great Barrier Reef, Coral Sea Marine Park and north-west WA. Survey data suggests Ashmore Reef Marine Park accounts for ≥1 per cent of the global population (Cannell and Surman 2020). Several thousand pairs also breed on Christmas (5,000 pairs) and Cocos (Keeling) Islands. The total Australian population and trends are unknown.