Sunday, February 21, 2021

 Light and Dark

The Little Eagle juveniles in the Canberra area have all fledged and are now flying freely around their local patches. They are still dependent upon their parents to supply them for most of their food, although they are beginning to catch prey for themselves. Hence, it is a good time to catch and band them for later recognition. There are two colour morphs of the species, light and dark, and it is useful to hold these birds in the hand to see just how different they are from one another.  

              

The bird on the left above is a dark phase individual and the one on the right is a light phase. Although both these birds are juveniles and as such have typical red colouring, once they moult into adult plumage they will still retain the dark or light markings. In these examples, the dark bird is a male and the other a female, but the sexes can be either phase. And the female is actually larger than the male as is usually the case, but it is difficult to show this in photographs.

Both birds have individually numbered metal bands on their right leg and a unique coloured alpha-numeric metal band on their left, in these cases both are red. So if any readers see any Little Eagles, please check their legs for such bands and report their location to this study. The light bird has also been fitted with a GPS-satellite-tag on her back so that her movements can be followed.

The bands are red in the modern sense, the birds are red in the old sense, as in a red dog. A term that has been used since long before bright dyes have been used.

The dark birds have a smokey appearance which is created by the broad dark markings on the breast. The pale straw colouring of this bird's crown contrasts with his dark face.

The dark streaks on the pale bird's breast show as narrow lines and more red shows through. Her crown and nape have rich red colouring.

No matter whether light or dark phase, all Little Eagles have bright sharp eyes.


Tuesday, January 5, 2021

From egg to fledge

This female Little Eagle began incubating her egg about 16 September 2020. Her head can be made out on the top right of the nest. This post gives a pictorial description of the incubation and development of their chick. The photographs were taken by Sandra Lauer and her partner Jeremy, from a concealed watch point in a wood 200 m from the nest on an overlooking hillside. The birds never showed any alarm at their occasional distant presence. Little Eagles can nest closer than this to places frequently used by humans. Most people never notice them and the birds carry on with their business.

The male, a pale phase bird, would deliver food to the female either directly to the nest as in this case with a rabbit, or take it to an adjacent tree where she would slip off to eat it. The males usually cover the eggs while the females are off. Most of the incubation is done by the females and most of the hunting by the males who hunt for the females as well as themselves.

After about 36 days, the egg hatched, which would have been about 23 October. But the chicks are difficult to see when small and the females brood them tightly for the first week or so. This shot was taken on 1 November when the chick was just over a week old. It is still pure white and downy, although it can now hold its head up and move about the nest.

A week later, the female spent much of the time shading the chick from the direct sunshine by standing over the nest. This is typical behaviour. Once the chicks are two weeks old they can control their own body temperature more easily and require less brooding by their parents, but excessive direct heat from the sun can overheat chicks.

Once the chick was three weeks old, it was much stronger, shuffling about the nest and watching over its surroundings. The first of the chick's dark feathers are beginning to show, especially its flight feathers which will be the largest. The female still stayed close by, as here, standing on the edge of the nest. The males continue to supply most of the food for all the family.

By the fourth week, the chick is much stronger, standing high on its feet, rather than its heels when younger. The bird is losing more and more of its down by now and it has a pie-bald appearance. Its wings are noticeably dark. The female spent less time at the nest with it, but she would have been watching from nearby. 

Six weeks old and the female was still feeding the chick, although by now it could probably tear up small prey itself. Just as when the chick was tiny, the adult presents little pieces of food delicately to the chick. The female is a dark phase bird so the sexes could be easily recognised.

At six weeks, most of the body feathers have grown in and only flecks of down are left on its back and wings. The chick's face shows up white still. The feathers on its back and on the topside of its wings are dark, much darker than those of the parent birds. That is because their feathers are faded by years of exposure to sunlight 

Wing stretching is frequently practiced, more and more so as the chick nears fledging age. The chick also spent much time walking along and jumping between branches over the next two weeks. Although the wings look fully feathered they are not quite full length. And the tail is noticeably short. But it is beginning to look like an eagle.

This was the last time the chick was seen in the nest, when about 8 weeks old on 17 December, in a typical squinting view of the nest through a telescope. The adults had been tending egg or chick for three months. And they will still have to care for the chick for perhaps another three months before the family breaks up and they all disperse to their separate winter quarters.

p.s. The fledgling has been seen perched in the nearby wood in January, calling when the adults brought in food. 

Friday, December 18, 2020

Fledging time


It is now mid-December, the main fledging period for Little Eagle chicks in the Canberra area. The birds are about 8 weeks old and spend much of their final days at the nest perched on nearby branches. This bird has cast almost all of its downy chick feathers. Now its wings are dark with near fully developed flight feathers. Even its head has lost its down, one of the last parts to do so, and the distinctive crest of a full grown Little Eagle fluffs up in the wind.

The chick, the bird on the right, is smaller than the adult female behind it, so it is probably a male and they are likely to fledge a few days earlier than larger female chicks. The tuft of under-down showing on its breast is where its crop is bulging and opening the feathers. This is quite normal and can even be seen in adult birds when they have gorged on a large meal. So this is a good sign that the bird has had ample to eat. 

Sunday, September 20, 2020


One bird's winter movements

All the Little Eagles that breed in the Canberra area are now back in their breeding territories after their winter away. A sample of six of these were fitted with GPS-tracking devices and their movements followed during this past winter. They followed similar routes and over-wintering areas as those described in the previous post below, in the second annual report. It will take time to fully analyse all these birds' movements, so for now, here is an example of one bird's movements during the non-breeding period.


An adult female Little Eagle, Y2, 
flying over her territory



The same bird in the hand after being fitted with a GPS-tracker and individually coded bands, Y2.


And a photograph of her face while in the hand. The plumage colouring is highly variable between birds, which helps individual identification.


This annotated map shows the route of this bird's return migration to Cape York in northern Australia. The large dots are locations where she spent an overnight stop. She left Canberra on 14 March 2020 and arrived at her over-wintering area on 24 March, a journey of ten days. She spent four and a half months in a well-defined area of tropical savannah. Then she set off on her return flight on 17 August, reaching Canberra on the 31st, after a slightly longer journey of 14 days. She is now back in the same territory she occupied in 2019.


Saturday, August 29, 2020

 Distant views

Real life eagle-watching is not like that portrayed on television. The birds are seldom seen in frame-filling format, rather they are specks in the sky or faintly discernable shapes sitting in trees. These views of Little Eagles in a tree next to their nest tree, give a true impression of the view of eagles through a telescope. Click on the images to see more detail.

This female was quite difficult to spot when she was sitting upright. It was only when she moved, and leaned forward that she became just a little more obvious.

Movement is often the main betrayal of any bird's postion and when her partner flew onto the branch, the two of them called bringing more attention to their presence.

The Little Eagles in the ACT area are now settling to breed and mating is frequently seen. This pair's nest has been built up with fresh branches and leafy twigs, ready for eggs. And another pair already have an egg, laid on the 19th of August. 

Friday, July 31, 2020

A new season on the way

Welcome home. The first Little Eagles have returned to their nests in the Australian Capital Territory and surrounding parts of New South Wales. Although it is still officially late winter there have been some bright sunny spring-type days and after some decent rainfall in autumn and winter the land is green, so different from the dry dust and smoke of last summer.


A pale morph male Little Eagle glides over his dark morph mate as she sits atop their nest tree. The tree is alive, only the top branches are dead.


The nest which has new sticks added, is concealed in the foliage.  


The pair were calling excitedly to one another, 
the male diving past her as she lifted her wings.


Then upon some signal between them, he jumped from the next branch and they copulated. Note how her tail is fully turned and tilted to one side, and his tail is firmly pressed over her cloaca. His talons are held forward and loosely closed as he balanced on his heels.


After a minute or so, he gently launched up off her back.


He landed next to her and both birds began preening and staightening their plumage.


Several minutes later, the male took off and went away hunting, soaring low over the nearby treetops. 


When the female took off about half an hour later later, she flew a different line, past her neighbours. And she quickly turned in alarm.


Her neighbours are Australian Magpies and one swooped very very close to her. The magpies have their nest three trees away and they will attack any animal they consider to be a threat to their nest, eggs or young, including humans. The eagle is more than capable of protecting herself, better than humans, and she casually drifted away to hunt over a nearby creek line.

Saturday, July 4, 2020

The third annual report on the study of Little Eagles breeding in the ACT area - 2020


A recently fledged Little Eagle, showing her uplifted crest.


THE BREEDING SUCCESS AND DIET OF LITTLE EAGLES IN THE ACT AND NEARBY NSW IN A DRY YEAR, 2019

Rae, S., Mulvaney, M., Fletcher, D., Wimpenny, C., Brawata, R., Kiggins, R., Stol, J., Davies, M.,  Roberts, D., and Olsen, P. (2020). The breeding success and diet of Little Eagles in the ACT and nearby NSW in a dry year, 2019. Canberra Bird Notes 44: 145-151. Open pdf

Abstract. Fourteen Little Eagle (Hieraaetus morphnoides) territories have been identified in the ACT in three years of study, although not all have been occupied in all years. In the ACT in 2019, spring rainfall was well below average and maximum temperatures above average. A minimum of ten pairs of Little Eagles were located in the ACT during the 2019–2020 breeding season. Nine pairs had nests and at least six laid eggs. A minimum of three pairs successfully fledged a chick each. Of four pairs that were monitored in nearby NSW, single chicks were successfully reared by three pairs and one nesting attempt was disrupted during incubation by a pair of Wedge-tailed Eagles (Aquila audax). Overall breeding success was lower than for 2018 but similar to 2017. The main prey types were: mammals (50%) of which rabbit was the main species; small/medium-sized birds (43%); and reptiles (7%). Similar proportions of mammals, birds and reptiles were eaten in 2019 and 2018, and a
higher proportion of mammals than in 2017.


Proportions of food types in the remains of Little Eagle prey collected during the breeding season in the ACT and nearby NSW in 2017 (n = 109), 2018 (n = 131) and 2019 (n = 96).

This year's report shows that Little Eagle breeding success was lower in 2019 than in the previous two years, which were also low. It was dry in the study area in all three years, especially so in 2019, and potential prey species were likely low in abundance. Rabbit has been the most commonly taken prey item over the three years of study and it is likely that drought conditions have affected their numbers and those of the other main prey, small-medium sized birds. These results show how it is important to study such birds as raptors over several or more years as long-term data are more likely to reveal any causes for their breeding success than single or even three years' data.

Friday, July 3, 2020

The second annual report on the Little Eagle study - 2019

An adult Little Eagle flies low overhead


PRELIMINARY RESULTS FROM STUDY OF LITTLE EAGLES IN THE ACT AND NEARBY NSW IN 2018–2019

Rae, S., Wimpenny, C., Mulvaney, M., Davies, M., Fletcher, D., Roberts, D., and Olsen, P.
(2019). Preliminary results from study of little eagles in the ACT and nearby NSW in
2018-2019. Canberra Bird Notes 44: 145-151. Open pdf

Abstract. There was a minimum of nine nesting pairs of Little Eagles (Hieraaetus morphnoides) in the ACT in the 2018/19 breeding season. Seven pairs laid eggs and five pairs successfully fledged a chick each. Two pairs were seen attending nests but were not known to have laid eggs. Four additional breeding pairs were monitored in nearby NSW; single chicks were successfully reared by three of these and one nesting attempt failed. The main prey type was rabbits (61%), then small/medium-sized birds (32%) and lizards (7%). More rabbits and fewer birds and reptiles were eaten in 2018–19 than in 2017–18. Samples of birds’ movements were followed with GPS-satellite transmitters. Adult males ranged mostly within 2-5 km of their nest sites and they left their breeding areas in early March. By April one had flown 2000 km to northern Queensland, one 450 km to Melbourne and another had ranged between 50 km west of the ACT and 100 km to the east. Juvenile eagles stayed mostly within 2 km of their nest sites before they left the area in early March. By April, one juvenile had dispersed 2000 km to Northern Queensland and another 450 km to south-east Victoria, via Yorke Peninsula in South Australia. A juvenile reared in the ACT in 2017 flew to south-east Queensland in its first winter, then to south-east Victoria via South Australia in the following spring and summer.


Flight paths of Little Eagles that dispersed from the ACT post breeding season: 
three adult males (D2, X2 and Z5) and three young birds (B6, D4 and V2). 

The highlight of this year's report was the distribution of the birds out of the breeding season. The above map shows how both young and adult birds dispersed widely across eastern Australia. Click on the link above to read the full report.


Thursday, July 2, 2020

Confirmation of Little Eagle Hieraaetus morphnoides migration by satellite telemetry

Publication of the results from a study of the movements of a Little Eagle out of the breeding season using data downloaded from a GPS satellite transmitter fitted to the bird.



Brawata. R., Rae. S., Gruber.B, Reid. S. & Roberts, D. (2019). Confirmation of little eagle (Hieraaetus morphnoides) migration by satellite telemetry. Australian Journal of Zoology, 66(4): 247-250.
https://www.publish.csiro.au/ZO/ZO18060 

Abstract. The post-breeding migration of an adult male little eagle (Hieraaetus morphnoides) was followed from south-eastern Australia to the Northern Territory using a GPS satellite transmitter. The bird bred in open woodland habitat on the edge of the city of Canberra, Australian Capital Territory (ACT), before it flew more than 3300 km in 18 days, to winter in an area of eucalypt savannah in the Northern Territory. It remained there for 59 days, within a range of ~30 km2 , after which the last signal was transmitted. The bird was subsequently resighted back in its ACT territory at the end of winter, thus completing a return migration. This is the first confirmation of post-breeding migration for the species.


Map showing the north western movement of the male Little Eagle from Canberra in the Australian Capital Territory, to Kalala Station, near Daly Waters in the Northern Territory.

The study group have fitted GPS tags to 13 Little Eagles to date and continue to monitor their movements. Other birds have so far been recorded as far west as the York Peninsula in South Australia around eastern parts of New South Wales and Queensland, then north as far as the Cape York Peninsula.

Acknowledgment to J Olsen who helped by catching and tagging the first bird followed in this study.

Wednesday, July 1, 2020

The first annual report by the group on the breeding ecology of Little Eagles - 2018


A young male Little Eagle, recently fledged in the ACT.

NOTES ON THE BREEDING ECOLOGY OF LITTLE EAGLES IN THE ACT IN 2017/2018

Rae, S., Fletcher, D., Mulvaney, M., Davies, M., Roberts, D., and Olsen, P. (2018). Notes
on the breeding ecology of Little Eagles in the ACT in 2017/2018. Canberra Bird
Notes 43: 186-193. Open pdf

Abstract. This is a preliminary summary of findings from the first year of a long-term study of the Little Eagle (Hieraaetus morphnoides) in and near the ACT. There was a minimum of nine nesting pairs in the ACT in the 2017-2018 breeding season. Six pairs laid eggs and four chicks were reared; one from each of two nests and two from another. Three pairs were seen with nests but were not known to have laid eggs. Pairs were observed at two other locations and the public reported five further potential breeding locations in the ACT. Two additional nests were located in nearby NSW; a chick was reared in one nest and the other nesting attempt failed. Nests were regularly spaced, and found in woodland, partially cleared woodland or a windbreak. Nesting eagles did not appear to avoid or prefer to be near various urban features. The main prey type was small/medium-sized birds, although the most eaten individual species was Rabbit, and lizards were also taken.

This was a short report on the initial findings of the study, a baseline upon which to build the on-going project. As such, it determined an initial sample of Little Eagle pairs, territories and habitats to monitor in the study. Click on the link above to read the full report.