Report on the 2019 nesting of the White-bellied Sea-Eagles

in the Newington Nature Reserve Forest at Sydney Olympic Park

Summary In the 2019 breeding season, the resident pair of White-bellied Sea-Eagles nested in the

Nature Reserve forest, and 2 eggs were laid. The study again revealed delayed incubation between

the laying of the two eggs. Both young eagles survived to fledge. The second eaglet hatched, SE24,

fledged at 77 days, before its older sibling and survived to be seen hunting on the Parramatta River

and has probably dispersed. The older eaglet SE23 fledged at 82 days but was found dead in its natal

territory at 103 days. In the period of this continuing study, the breeding success has been 45.5%,1

with an average of around one juvenile successfully fledged each season.

Introduction

There has been a Sea-Eagle nest in the Newington Nature Reserve at Sydney Olympic Park by the

Parramatta River for many years, with a succession of eagle pairs renovating a nest in the breeding

season. There are few early records of successful breeding however and several eagles were found

dead. Following the death of a pair of breeding eagles in 2004, necropsy and chemical analysis of

tissues was undertaken in order to determine the cause of death. Further study was recommended.

Their success or failure appears to be closely linked with environmental conditions, particularly the

accumulated Persistent Organic Pesticides in Homebush Bay and the Parramatta River. Nesting

failure has been caused by infertile eggs, sibling rivalry, Beak and Feather Disease, or Trichomoniasis

(see previous reports for more detail).

As in previous years since 2009, the breeding relationships, behaviour and diet of the White-bellied Sea-Eagles were studied using video CCTV cameras and by limited physical observation during daylight hours, from the time of nest renovation to fledging and beyond where possible. In early 2019 a new Research Proposal was submitted and all approvals gained. The Sea-Eagle is listed in NSW as vulnerable under the Biodiversity Conservation Act 2016 and nationally in Environment Protection and Biodiversity Conservation Act 1999 as Marine and Migratory.

Nest renovation

Renovation of the previous nest continued from April, with both eagles bringing sticks and fresh

leaves to renovate the previous nest. The male brought prey items to the nest and mating at or near

the nest was recorded. Duetting was commonly observed, establishing their bond.

Delayed Incubation 2019

The eggs were laid some 73 hours apart. Egg 1 SE23 was laid at 17:37 on June 16. The second egg SE24 was laid at 18:43, on June 19. The first night after egg 1 was laid, when the weather was cold, the female incubated for only 5 hours,

1 Defined a successfully fledged

leaving the egg uncovered for 5.5 hours. As usually it is the female incubating at night, it was unusual to see that the male incubated for over 2 hours, after 3:00am, possibly due to disturbance nearby. The next day, both shared daytime egg duty, with the egg uncovered for over 4 hours. On the second night she again left the egg uncovered, for nearly 6 hours. Graph 1 Number of hours the first egg was uncovered during Incubation before laying of egg 2

Daytime incubation and care at the nest was again shared by both adults. As lay of the second egg approached, incubation time increased until the second egg was laid . Full incubation then continued, with the female on at night, assisted by the male during the day. Graph 2 Daytime Incubation between egg 1 and egg 2

During incubation, the male brought prey to the nest, though not every day. The female brought food a few times, though both probably caught and ate prey elsewhere. Prey brought during this time was mainly fish.

0:00

1:12

2:24

3:36

4:48

6:00

7:12

1 2 3 4 5

NightDay

0:00

1:12

2:24

3:36

4:48

6:00

7:12

8:24

1 2 3 4 5

femaleincubatingmaleincubating

Egg 1 was uncovered nearly 13

hours total at night and nearly 9

hours by day before egg 2 was

laid

During the day, both adults

incubated, with the female a

total of 23 hours and the male

nearly 27 hours

Hatching

The first chick SE23 hatched on July 26, after 40 days incubation.

The second chick SE24 was first seen early in the morning, on the 39th day from lay. Earlier hatching

progress overnight was hidden, as the female brooded in the cold. The two eggs were laid around 73

hours apart and hatched about 33 hours apart, after delayed incubation of the first egg.

Nestling stage

SE23 received food from the female on the first day

after hatching, taking small morsels of whiting from

the female’s beak. Initially the female mainly fed the

chicks at the nest, with the male contributing more

as the chicks progressed. The number of feedings

lessened, as the chicks grew and were able to self-

feed at the nest with prey the parents brought.

Graph 3 Daily Feeding Activity at the nest after hatch

0

2

4

6

8

10

12

14

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82

female feeds young

Male feeds young

Nu

mb

er o

f fe

edin

gs

Days since hatch of SE23 until fledge

Graph 4 Daily Prey Delivery at the nest after hatch until fledge

Initially the male brought most prey to the nest, with the female contributing more as the breeding

progressed. The prey was mostly fish or

birds. Fish included Bream, Whiting and

Leatherjacket and birds- pigeons and

Silver Gulls. A few eels were delivered as

well as left-overs from previous

deliveries. (see Appendix for some prey)

Bird prey was often plucked at the nest.

Silver Gulls were commoner later in the

season.

Sibling Rivalry

Though there was delayed incubation, allowing some “catch up” between the two chicks, there was some initial competition from the bigger, first- laid chick SE23. At times the smaller chick SE24 was submissive and was only fed when the other was satisfied. An interesting observation was when the male brought a bird, possibly pigeon, to the nest on one occasion. He plucked the bird and this bloody prey seemed to stimulate aggression in the bigger chick, SE23. It picked and pulled at the head of its sibling, removing chunks of fluff. A report on nesting Bald Eagles commented that red,

bloody prey seemed to stimulate

aggression in the nest. The normal prey,

0

1

2

3

4

5

6

7

8

9

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82

Female brings prey

Male brings prey

231 fish64 birds4 eels

Days since hatch of SE23 until fledge

SE24 in submissive posture, being aggressively pecked by

its sibling

as for these Sea-Eagles, was fish. 2

As the season progressed, this competition

decreased. The sibling rivalry did not continue as in

the previous year 2018, when competition caused

the death of the smaller chick from lack of food.

Both eaglets gradually began to self-feed, mantling

over prey and eventually feeding themselves from

prey brought to the nest by the parents.

Fledging

As in the past years, as the eaglets grew and developed, they exercised their growing wings, jumping

and flapping in the nest bowl. SE24 branched at just over 10 weeks, flapping to a branch above the

nest and then back to the bowl. It was surprising to see that the younger eaglet SE24 branched

before its sibling and then fledged a few days later at 77 days, taking its first flight away from the

nest, before returning safely some time later. SE23 fledged 3 days after the younger, at 82 days

from hatch.

At the time there was an aggressive magpie near the nest, which swooped the eaglets on the nest.

SE24, newly fledged, was knocked by the magpie and fell to the ground. A circling fox was seen as

the camera was focussed on the fallen eaglet, which defended itself with out-stretched wings.

Fortunately the fox was scared off and the eaglet flapped to safety in a low tree.

After fledging, the adults initially brought prey to

the nest, or fed the young birds elsewhere in the

forest. The eaglets were eventually no longer seen

on the nest.

SE 24 was seen by observers in mangroves on the

Parramatta River, the favourite river roost of the

adults. It was seen taking prey from the adults and

flying strongly over the following weeks.

SE23 was harder to find, though she was

photographed on the ground in the casuarinas forest a week or

so after fledging. Several days later she was found again on the

railway track near the nest. She was seen to fly strongly back

into the forest. However, no definite observations were made

again of SE23 and she was found dead on the disused rail track

at 103 days.

2 page 88, The Bald Eagle Haunts and Habits of a Wilderness Monarch. Jon M. Gerrard and Gary R Bortolotti

SE 24 at the river roost with an adult

SE 24 in submissive posture while the other is fed

SE 23 in the casuarina

forest at 87 days

The dead eaglet was taken to the Taronga Wildlife Hospital for necropsy, which revealed she was

emaciated, the muscle mass was reduced and there were no visible fat deposits. The Pathology

Report summarised “Based on the bird's very poor body condition and the presence of abnormal

ingesta in the ventriculus it seems likely that the animal failed to thrive once fledged”.

SE 23 at 103 days from hatch, showing some feather damage and decomposition

SE24 flying free along the river and roosting on the mangroves. February 2020 Photos :C. Cook

This on-going project contributes to knowledge about and protection of this Vulnerable species. The

project also satisfies activities suggested by the Office of Heritage and Environment to protect the

White-bellied Sea-Eagle:

• Protect known populations and areas of potential habitat from clearing, fragmentation or disturbance.

• Establish 'buffer zones' around nest sites to limit disturbance by humans or human activity. Where nests are located in extensive undisturbed bushland a minimum buffer distance of 500m should be maintained. Where nests are located closer to existing developments a minimum buffer distance of 250m should be maintained, along with an undisturbed corridor at least 100m wide extending from the nest to the nearest foraging grounds.

• Conduct annual, broad surveys to monitor known nest sites, locate new nest sites, determine breeding success and trends in populations, and determine areas of critical habitat.

• Educate the public about the sea-eagle and its status, promote the conservation of the species, and encourage members of the public to report sightings of sea-eagles to the appropriate authorities. (http://www.environment.nsw.gov.au/threatenedspeciesapp/profile.aspx?id=20322)

Acknowledgements The EagleCAM research project team acknowledges the assistance of Sydney Olympic Park Authority

in approving this research and facilitating access to the Nature Reserve and other facilities.

I also acknowledge advice and approval for conducting the activity within Newington Nature Reserve from NSW National Parks and Wildlife Service Cumberland Area Manager and the rangers.

I acknowledge the essential assistance from the EagleCAM team, Geoff Hutchinson, Bob Oomen and Chris Bruce, for camera installation and maintenance and all things technical; Shirley McGregor for managing the live-stream and internet issues: and a wonderful team of volunteers, too numerous to name, for monitoring and keeping observations, managing Facebook and the website and more: and our Supporters, for funding this project.