From Tropical Topics newsletter, No. 73,
May 2002, produced by Stella Martin at the Queensland Environmental
Protection Agency. Download the PDF to read the whole issue.
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Wedge-tailed eagle
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Wedge-tailed eagles are impressive birds. The largest eagles in
Australia, and among the largest in the world, they have wingspans
of up to 2.5 metres. Often, all that can be seen is a small shape,
high in the sky, gliding on the thermals with its keen eyes
searching the ground for food. The wedge-tailed eagle once carried
a bounty on its head. Between 1927 and 1968, 150,000 bounties were
paid in Western Australia. Ten thousand were paid in Queensland in
a single year. The circumstantial evidence was not good for the
eagles. Often seen feeding on newly-dead livestock, they were
assumed to be a major predator. However, wedgies prefer fresh
carrion, if it is available, to hunting and the livestock they have
been observed eating was usually dead when they got there, or if
killed by the birds, would probably have already been weak or
orphaned. Road kills are a great bonus for these birds although,
being slow to take off, they sometimes become the next victim, left
for dead in the verge next to their erstwhile dinner. A wide
variety of animals are also hunted, from lizards to ground-foraging
birds as big as emus, and mammals — the main dietary
item — including wallabies, kangaroos, possums and
introduced animals. Rabbits are ideal prey making up to 90 percent
of their diet in some areas, although the decline in their numbers,
due to the release of the calicivirus, means that the birds have
had to turn to other sources of food.
These eagles construct appropriately large nests, weighing up to
400 kg, usually in strong trees. Maintaining a territory, and
probably the same mate, for life, the birds build several nests,
using them on a rotational basis. Usually two eggs are laid and if
food is available both will survive. Otherwise, the older chick may
kill the smaller one. At about the age of eight months the young
birds leave their parents' territories and go off travelling
— a banding study in Western Australia indicated that they
move an average of 228 km.
One adventurous youngster journeyed 748 km in just 11 months
while another, in Queensland, has been found 868 km from its
parental home.
Young birds are brown with golden-brown feathers on the nape and
upper back. Most gradually darken with age, eventually becoming
almost entirely black when mature, at about five to seven years of
age. Some, however, retain their juvenile colours. Wedge-tailed
eagles can live for over 40 years. Apart from its large size, its
long legs with feathered 'trousers' and pale bill are distinctive
features. In the air, its long diamond shaped tail is
distinctive.
To see a recent list of research findings on the wedge-tailed
eagle click here .
Red goshawk
This bird is Australia's rarest and most threatened bird of
prey. Favouring riverine forests as well as tropical and
subtropical woodlands and open forests, it occurs across the top of
Australia. On the east coast, it occurs as far south as New South
Wales but has now virtually disappeared from this state. These
birds are swift hunters using their strong feet and claws (the
largest, proportionally, of any Australian raptor) to take live
prey - mainly medium to large birds up to the size of Australian
brush-turkeys and red-tailed black cockatoos. Each pair needs a
large territory — up to 200 square km. The main threat facing
these birds is habitat loss and fragmentation, particularly around
watercourses. Other threats include fires, lit late in the dry
season, which destroy nesting trees and active nests of both the
goshawks and their prey species, as well as shooting and illegal
theft of eggs for collections. To see a recent list of research
findings on the red goshawk click here
If you see any red goshawks in Queensland, or just over the
Northern Territory border, Greg Czechura, Queensland Museum would
be keen to hear about it. He is also happy to answer any queries
about raptors.
His contact details are listed below.
Black kites
These birds are known as fire hawks in places, are attracted by
the smoke from bush fires. Large numbers can be seen circling on
thermals above burning grasslands, keeping a sharp lookout for
animals fleeing in panic. Reptiles, rodents and insects are taken.
So useful are fires to black kites, there are unconfirmed reports
of them dropping burning sticks to extend the fire. (A black kite
has also been observed dropping bread scraps into a river to
attract fish to the surface.) To see a recent list of research
findings on black kites click here .
Brown falcon
The more solitary brown falcon also takes advantage of bush
fires, pouncing on its victims from a perch where it has been
waiting quietly. It rarely chases prey on the wing. To see a recent
list of research findings on brown falcons click here .
