Little Eagles in the ACT and nearby NSW in 2017/18

extract from p 6 Gang-Gang April 2018
Newsletter of the Canberra Ornithologists Group Inc.

A brief summary from the Little Eagle Research Group

The Little Eagle Research Group (LERG) are pleased to report that they confirmed a minimum of nine nesting pairs of Little Eagles in the ACT in the 2017-2018 breeding season. Six of the pairs laid eggs and four chicks were reared, one from each of two nests and two from another. At two other locations, pairs were observed by members of the group, and the public reported five further potential locations in the ACT; however, these have not been included as breeding birds in 2017 because time ran out to ascertain their breeding status. Two additional nests were located just over the border in NSW.

One pair incubated an infertile egg for a month longer than the usual incubation period before they abandoned their effort and another pair lost their egg to a predator, possibly a raven. There was no known reason why the third pair failed to rear a chick. Of the two nesting pairs in nearby NSW; one fledged a chick, and the other pair hatched a chick, but it died due to unknown causes while still small. All these known nesting areas and other possible locations will be monitored in future years to build a more comprehensive understanding of the status and breeding ecology of Little Eagles in the ACT and surrounding NSW.

Two live webcams were installed above one of the nests to record the eagles’ nesting habits and collect data on breeding behaviour. The cameras were installed in late winter, at a time when the birds were known not to be present at the site, on 20 July 2017. The nest chosen for this was one used by a pair of eagles which successfully reared a chick in 2016/17. The male of that pair was the bird which had been tagged and tracked via satellite to the Northern Territory. He returned to the nesting territory in August, but was never seen at the nest. Another male was subsequently seen with a female at that nest, but it is not known what became of the tagged male.

The cameras were successful and many people saw the eagles live, worldwide. The birds took possession of the nest, added fresh material, mated there and the male brought food to the female on the nest. Evidently, they accepted the cameras. However, as many eagles of various species do, this pair switched nests to lay their eggs about 2 km away. Unfortunately, they failed to rear a chick, with the cause unknown, and the female was last seen and left undisturbed on the nest in October. It was not clear at the time why the birds changed nests, but a Pied Currawong was seen feeding on something in the base of the original nest and video footage later demonstrated that the nest was infested by beetle larvae. The eagles possibly detected these earlier, which could explain why they moved.

Non-live cameras were also set up in advance of the breeding season at two other nest sites. One was at another alternative nest site to the pair where the webcam was set and was not used by the birds, although they were recorded mating on it. The eagles whose territory held the third nest camera elected to use another nest about 200m away and successfully reared a chick.

A tracking-tag was fitted to a female chick when she was large and almost fully feathered, allowing her to be followed via satellite after she fledged in December. She moved increasing distances from the nest as she grew older and stronger, flying over urban areas and visiting several urban nature reserves of the ACT, flying up to 7 km from her nest area and to more than 1400 m attitude, 800 m above street level. Then on 11 March, she left the ACT and was last recorded in Queensland, north-west of Brisbane, having travelled over 1000 km (data accessed 22 March 2018).

The Little Eagle Research Group is an informal, collaborative study group which aims to monitor and assess the status and ecology of the Little Eagle in the ACT and nearby NSW. This is being done part-time, with the combined knowledge, expertise and resources of: Michael Mulvaney, Claire Wimpenny and Renee Brawata (Conservation Research Unit, ACT Government); Jacqui Stol and Micah Davies (CSIRO); David Roberts (Ginninderry); Don Fletcher, Stuart Rae and Penny Olsen (Australian National University); and Stephen Debus (University of New England). The group is grateful to COG members and the general public for generously sharing sightings and other information; and to property owners and managers for access to sites and care for the birds.

Stuart RaeLittle Eagle

Stuart Rae