Lesser Frigatebird, Fregata ariel

The Lesser Frigatebird (Fregata ariel) is a species of frigate bird. In nests in Australia, along with other locations. There is a single recording from the Western Palearctic, from Eilat in the Gulf of Aqaba.

The Lesser Frigatebird or Least Frigatebird is said to be the most common and widespread frigate bird in the Australian seas. It’s common in tropical seas breeding on isolated islands, including Christmas Island located in the Indian Ocean in recent years. These birds are most likely to be seen from the mainland prior to the onset of a tropical cyclone, and one this subsides, they disappear again.

It’s the smallest of the three frigate birds found in Australian waters, measuring about 30 inches in length. Like all frigate birds, the male has a large red sac on the front of the throat which inflates during courtship. Courtship display also involves a variety of calls, bill rattling, and spreading of the wings. The male is mostly all black except for a white patch on the flank with stretches on to the underwing as a spur. The males also have a pale bar on the upper wing. Females have a black neck and head which a white collar and breast as well as a spur extending onto the underwing. The female also has a narrow red ring around her eye. The juveniles and immature birds are more difficult to differentiate but the presence of the spurs of white in the armpits aids in distinguishing.

Frigate birds are built for flying, they rarely ever swim and cannot walk but can manage to climb around the trees and bushes in which they nest. They have a very light skeleton and long narrow wings and are experts in the air. Their name most likely derives from the fact that they harass other sea birds such as boobies and tropic birds as they return to their nests from feeding, forcing them to disgorge their catch, which is then swooped upon and caught by the frigate birds before it reaches the water below them. This practice appears to be more common among the females, but probably only accounts for a fairly small proportion of the diet, which mainly consists of squid and flying fish scooped up from the surface of the water.

Breeding appears to occur between May and December in the Australian region. They nest in trees and both sexes contribute to the construction of the nest and incubation and feeding of the young. One egg is laid which takes six to seven weeks to hatch. The fledglings are not left alone for another seven weeks or so for fear that they may be attacked and eaten by other birds including other frigate birds. They stay in the nest for approximately another six months until fledged, but they are cared for and fed by their parents for quite a long time after that.

Image Caption: Lesser Frigatebird, Western Australia. Credit: Aviceda/Wikipedia (CC BY 3.0)