Christmas Island Goshawks
The Christmas Island Goshawks (Accipiter fasciatus natalis) is a bird of prey in the goshawk and sparrowhawk family Accipitridae. It is a threatened endemic of Christmas Island, an Australian territory in the eastern Indian Ocean.
Taxonomy
The taxon was described in 1889 by Lister as a full species, Accipiter natalis. Since then there has been debate as to whether its affinities lie with the Brown Goshawk or the Grey Goshawk (A. novaehollandiae). In the 2004 national recovery plan for the taxon, it is treated as a subspecies of the Brown Goshawk, though the possibility has been raised of elevating it to the species level again. Christidis and Boles (2008) treat it as a subspecies of the Variable Goshawk (A. hiogaster). Here it is treated as a subspecies of the Brown Goshawk pending further study of its genome.
Description
The Christmas Island Goshawks is smaller and has more rounded wings than the nominate subspecies. Coloration is broadly similar, differing in that the hindneck, cap, and ear coverts are dark grey, lacking a brown tinge. Females are distinctly larger than males.
Distribution and habitat
The goshawk is restricted to the 135 km2 of Christmas Island where it is found in the tropical rainforest that covers 75% of the island, as well as in other habitats there such as regrowth forest and the edges of clearings.
Breeding
The goshawk builds nests high in tall forest trees. Until it’s time to breed, this species of Goshawk lives solitarily. They breed from August to January, during which the mates will be reunited, and will fly and call in unison.
Feeding
The goshawk feeds on a wide range of vertebrates and invertebrates, including birds, mammals, reptiles, and insects. It takes its prey from the ground or in flight. It will hunt from a perch or chase birds through the forest.
Status and conservation
The goshawk is listed as endangered under the Environment Protection and Biodiversity Conservation Act 1999. There are no detailed population statistics for the goshawks, though the population is small and it has been estimated that there are no more than 100 mature birds, or 50 breeding pairs, on the island.
The principal threat comes from yellow crazy ants which were accidentally introduced to the island. The threat is not only that of ant predation of goshawk nestlings but also indirectly from potentially massive changes to the ecology of the island caused by the ants.
