Forest Little Eagles

A juvenile Little Eagle swings low over a dense forest canopy in the Namadgi National Park, ACT.

This was a recently fledged bird from a nest hidden deep in the forest. The Little Eagle Research Group have watched the adult birds over the breeding season, however viewing is limited due to the topography of deep undulating hills cloaked in forest, with few lookout positions for watching their movements. Then this week, the nest was found.

The group have observed birds hunting over woodland and dense forest canopies in other parts of the ACT, and they have data from GPS-tagged birds which support this. One tagged bird in another site spent much of his time over the dense forest of the Brindabella range, including the higher ridges at approximately 1300m, then in the non-breeding season he moved to the coastal forests of NSW. That bird seemed to specialise in hunting camopy birds.

Birds have been seen to dive into the canopy to snatch birds from the branches. They have been seen to catch Crimson Rosella, Yellow-faced Honeyeater and what was either a Striated Pardalote or a Weebill. Both of these latter species were in a mixed flock and as the eagle wrapped its talons around the whole bird, it couldn't be determined which species was caught. The prey remains found below this nest were of Crimson Rosella, King Parrot, Red Wattle bird, White-eared Honeyeater and Black-faced Cuckoo-shrike. The latter have been abundant in the ACT this year and other eagles have also been eating them.

The juvenile, a male by its smaller size, spent its time perched in the canopy watching for its parents bringing food, or taking short turnaround flights in about a 200m radius of the nest. This open perch on a dead branch was less typical than the more favoured branches below the top of the canopy. Much of the forest was burnt in 2003 and there are still dead trees standing amongst the re-established canopy.

The nest was set in a clump of mistletoe on a lateral branch in the lower part of the canopy. And there were remains of an older nest underneath the current one. So, the birds had likely nested there in previous years when they had been seen in the same area.

It was such a delight to see a true wild nest in wild habitat. So many nest sites from our and other studies are in human-manipulated habitat, such as woodland partially cleared for farmland. 

This is the nest area seen from outside the canopy. There is no sign of the nest. The birds were generally quiet, the fledgling seldom called and the birds were difficult to see when perched, even from imediately beneath. They sat quietly watching us when we stood beneath them. Only glimpses of birds in flight gave hints of the nest location.

Little Eagles in the ACT have been described as rarely seen in the the more heavily forested parts of the ACT (Taylor and Canberra Ornithologists Group 1992). And  they have been described as avoiding dense forests and not breeding above approximately1000m (Debus 2017). Yet this nest was in dense forest at 1265m. These birds could have been easily overlooked, and other Little eagles would likely be just as difficult to find in such habitat. How many more Little Eagles are breeding in such extensive areas of dense forest, not only in the ACT but elsewhere in the country. Do some eagles specialise in hunting canopy birds and other eagles specialise in hunting terrestrial prey in more open habitats. Or are individuals birds adaptable to either.

The more we study the more questions we open...

References:

Debus, S. (2017). Australasian Eagles and Eagle-like Birds. CSIRO, Australia.

Taylor, McComas. & Canberra Ornithologists Group (1992). Birds of the ACT - An Atlas, Canberra Ornithologists Group and Australian Capital Planning Authority, Canberra.