The fourth annual report on the study of Little Eagle breeding in the ACT area - 2020
A fledgling Little Eagle perches on a branch at the edge of its nest while the adult female looks on from a branch behind the nest.
BREEDING SUCCESS AND DIET OF LITTLE EAGLES IN THE ACT AND NEARBY NSW IN 2020
Rae, S., Mulvaney, M., Wimpenny, C., Brawata, R., Stol, J., Davies, M., Roberts, D. and Olsen P. (2021). Breeding success and diet of Little Eagles in the ACT and nearby NSW in 2020. Canberra Bird Notes 46: 56-73.
Abstract. Twelve Little Eagle (Hieraaetus morphnoides) territories were occupied in the ACT in 2020. There were nine pairs, seven of which were confirmed to have nests, and it is not known if the other pairs had nests. There were single birds, a male and female, at two territories, and at one previously successful territory a female was seen with a lined nest but no male and no eggs were seen. Eggs were laid in at least six nests and young were hatched in all nests with eggs laid. At least three chicks died while still young, two in each of two nests with single chicks. Prolonged heavy rainfall was a possible cause of failure at these two nests and one nest was disturbed by Pied Currawongs (Strepera graculina) and Brown Goshawks (Accipiter fasciatus) probably causing chick death. A minimum of three pairs successfully fledged one chick each. In nearby NSW, four previously known nest sites in NSW were occupied and single young fledged from all. One chick died in one of these nests where two chicks had hatched. A fifth, new, pair with a nest were located but they apparently did not lay eggs. Despite higher loss of nestlings than in the previous three (drought) years, overall breeding success was slightly higher. The diet was composed of mammals (60.6%), of which European Rabbit (Oryctolagus cuniculus) was 52.4%, small/medium-sized birds (36.1%) and reptiles (3.3%). Rabbits made up a greater percentage of the diet than in the previous three breeding seasons.
Another fledgling Little Eagle, a dark phase one, flies over its nest area.
After three dry years, the wet winter and spring in 2020 began promising for the Little Eagles breeding in the ACT. The vegetation grew back after the rains and rabbits, a major food source for the eagles, were abundant. A higher proportion of eagle pairs laid eggs and hatched young than in the previous three years. However, the wet weather continued with some prolonged heavy rainfall when the chicks were still downy and vulnerable to hypothermia. This could have been the main cause of failure this year, or perhaps the adults could not find enough food during the rain periods and the chicks starved. What happened is uncertain, and it is only when we study birds closely that we detect such occurrences. One reason why this is a long-term study, is to collect data from enough years to assess how such factors as annual variations in weather can affect the birds breeding success.