The fifth annual report on the study of Little Eagle breeding in the ACT, 2021

A particularly dark fledgling Litte Eagle, the offspring of two dark phase parents.

THE BREEDING SUCCESS AND DIET OF LITTLE EAGLES IN THE ACT AND NEARBY NSW IN A WET YEAR, 2021

Rae., S., Brawata, R., Wimpenny C., Stol, J., Roberts, D., Mulvany, M., davies. M. and Olsen, P. (2022). The breeding success and diet of Little Eagles in hrte ACT and nearby NSW in a wet year, 2021. Canberra Bird Notes 47: 81-87. (pdf copy)

Abstract. Monitoring of Little Eagles (Hieraaetus morphnoides) breeding in the Australian Capital Territory in 2021 was impaired by COVID-19 restrictions. It was a wet year. September and November, when most eagles lay eggs and hatch young, were notably wet. Six Little Eagle territories were recorded in the ACT in 2021. There were at least five pairs with nests, and a lone male was recorded at a sixth nest. All pairs laid eggs and one failed during incubation. The chicks in three nests died during periods of prolonged heavy rainfall and one pair raised a chick to fledging. In NSW, three pairs raised a single chick each. A known nest was built up in another territory in NSW but no birds were observed at it. The overall number of chicks reared per pair was 0.50. The proportion of rabbits in the birds’ diet was low compared with the three previous years. How weather and diet might affect the breeding success of Little Eagles are discussed.

The remains of a fledgling Little Eagle that died when a severe hail storm passed over the nest area. The partly scavenged body lay directly below the nest.

The wet weather continued in 2021 with mixed effects on the Little Eagles. All known pairs laid eggs which is indicative of a good food supply. Although rabbits were abundant, fewer were eaten by the eagles, perhaps because they had less access to them due to the prolific growth of tall grass and weeds, particularly thistles. The tall sward of dried thistle stalks from the previous year were thickened by fresh growth in 2021, presenting a formidable barrier to an eagle trying to dive after any terrestrial prey. The diet was supported by a higher proportion of birds than in the three previous years, so food was not likely a cause for breeding failure. Rather, severe storms with strong winds and high rainfall were more likely the main cause of breeding failure. This was supported by the remains of two chicks found below their nests and another that disappeared, all after storms. The direct and indirect effects of high winds and rain will be monitored in future years.