Australasian Eagles and Eagle-like Birds

190 Pages·2017·23.64 MB·English

by  Stephen Debus

Eagles are awe-inspiring birds that have influenced much human endeavour. Australia A
AUSTRALASIAN
U
is home to three eagle species, and in Melanesia there are four additional endemic
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species. A further three large Australian hawks are eagle-like. Eagles, being at the top T
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of the food chain, are sensitive ecological barometers of human impact on the Earth’s
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ecosystem services, and all of the six Australian species covered in this book are L EAGLES AND
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threatened in at least some states (one also nationally). Three of the four Melanesian
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tropical forest endemics are threatened or near-threatened. I
A
N
EAGLE-LIKE
In Australasian Eagles and Eagle-like Birds, Dr Stephen Debus provides a 25-year
E
update of knowledge on these 10 species as a supplement to the Handbook of A
Australian, New Zealand and Antarctic Birds (‘HANZAB’ ) and recent global treatises, G
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based partly on his own field studies. Included are the first nest or prey records
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BIRDS
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for some Melanesian species. This book places the Australasian species in their

regional and global context, reviews their population status and threats, provides new A
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information on their ecology, and suggests what needs to be done in order to ensure
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the future of these magnificent birds.

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A
G
ABOUT THE AUTHOR
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Stephen Debus has undertaken research on and written E
-
about raptors for nearly 35 years. He completed a PhD and L
I
K
postdoctoral research in Zoology, on declining woodland
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birds. He now works as an ecological consultant and is
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an honorary research associate at the University of New I
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England. In 2015, he was awarded BirdLife Australia’s D.L. D
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Serventy Medal for ornithological publication, recognising
his role as Australia’s longest serving ornithological editor
and contributions to the field, including over 130 papers,
the Whitley Award-winning Birds of Prey of Australia: A S
t
e
Field Guide, 2nd edition (CSIRO Publishing 2012), and p
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work on the raptor sections of the Handbook of Australian,
e
n
New Zealand and Antarctic Birds, Volume 2.

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STEPHEN DEBUS
Australaian_Eagles_cover_artwork.indd 1 6/03/2017 2:58 pm
AUSTRALASIAN
EAGLES
AND EAGLE-LIKE BIRDS
STEPHEN DEBUS
In loving memory of Rev. Graham Debus (1929–2016), deceased before this book
went to press, though having read the preface acknowledging his profound
influence and contribution to my ‘eagle’ life.
AUSTRALASIAN
EAGLES
AND EAGLE-LIKE BIRDS
STEPHEN DEBUS
© Stephen Debus 2017 Front cover: Female Little Eagle (light morph) with
crest raised. Photo: David Whelan.
All rights reserved. Except under the conditions
described in the Australian Copyright Act 1968 and Back cover: Stephen Debus with a juvenile Little Eagle
subsequent amendments, no part of this publication (dark morph), just banded. Photo: Sofia Debus.
may be reproduced, stored in a retrieval system or
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Debus, Stephen J. S., author.
autonomously from the research activities of the
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Debus. Organisation (CSIRO). The views expressed in this
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Eagles – Australasia – Geographical distribution.
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Eagles – Australasia – Identification.
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Foreword
Growing up in a semi-rural area (now largely bricked over by housing estates), my
friends and I were lucky to enjoy a childhood climbing trees, building rafts, falling
in the river and interacting with Nature. My knees were permanently covered in
dirt and I thought birds of prey were simply amazing – the ‘king of the skies’. I
spent many hours quietly watching kestrels hovering majestically over the fields,
their motionless head pointing into the wind while a pair of sharp eyes scoured the
fields for tasty mice, or a wriggly worm, and then the dramatic swoop. A
captivating natural-history lesson. A little farther across the fields, a pair of Barn
Owls nested in a large old oak tree. In the evenings my friends and I would quietly
perch in a nearby tree and watch as they raised a young family. And we’d unpick
the pellets regurgitated on the ground – a mash of bones, teeth, claws and beaks
– to speculate about their dinner.
Sadly, unsustainable development is breaking our connection with Nature and
slowly destroying our natural life-support systems. BirdLife Australia’s 2015 State of
Australia’s Birds headline report showed significant declines in some raptor species.
As these birds are generally at the top of the food chain, they are ‘umbrella’ indicators
of biodiversity. It’s a simple equation: more concrete, no trees, no small mammals
(and fewer birds), no birds of prey. All six Australian species covered in this book are
threatened in at least some states (and the Red Goshawk globally as well).
Good research is essential so that we can apply the best available knowledge on
these birds’ ecology, population trends and threats to inform practical action for
their conservation. If we know the solutions, and enough people care, we can
mitigate threats and recover endangered birds. Banning dichlorodiphenyl-
trichloroethane (DDT) pesticide in 1987, for example, resulted in a dramatic
increase in the reproductive success of birds such as Peregrine Falcons in Australia.
Stephen Debus is a renowned expert on our unique raptors and, in 2015,
received BirdLife Australia’s esteemed Serventy Medal for outstanding published
work on birds. Stephen’s expertise is founded on an encyclopaedic knowledge and
many long hours spent in the field. His first published paper was a short note on
v
vi Australasian Eagles and Eagle-like Birds
Wedge-tailed Eagle behaviour and his hundredth was also an acclaimed paper on
Wedge-tailed Eagle biology. The success of BirdLife Australia’s Australasian Raptor
Association owes much to Stephen’s prominent role and commitment. It is a group
founded to promote the study, conservation and management of our birds of prey,
including through a regular journal entitled Boobook; and many of its articles
feature the by-line: Stephen Debus.
Along with BirdLife Australia’s citizen-science Atlas program and digitisation
of the Handbook of Australian, New Zealand and Antarctic Birds (HANZAB) – the
premier compendium of bird knowledge (yes, some raptor accounts co-authored by
Stephen Debus, as are many key post-HANZAB eagle papers) – this new book
further updates and advances our knowledge for the conservation of Australia’s
eagles. With the help of conservation champions like Stephen, and readers like
yourself, BirdLife Australia can ensure that actions taken to protect birds and
Nature are informed by good science. Enjoy this book. I hope it inspires you to help
us protect our amazing raptors.
Paul Sullivan
Chief Executive Officer, BirdLife Australia
Contents
Foreword v
Preface ix
Photographer’s acknowledgements xiv
Introduction xvi
Part I Sea-eagles 1
White-bellied Sea-Eagle 3
Sanford’s Sea-Eagle 19
Part II Harpy eagles 27
New Guinea Harpy Eagle 29
Part III Booted eagles 37
Wedge-tailed Eagle 39
Gurney’s Eagle 60
Little Eagle 65
Pygmy Eagle 85
Part IV Australian eagle-like hawks 91
Black-breasted Buzzard 93
Square-tailed Kite 104
Red Goshawk 122
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viii Australasian Eagles and Eagle-like Birds
Epilogue 134
Bibliography 139
Other sources of information 163
Index 165
Preface
The impetus for a popular-scientific monograph on the Australian eagles came
mainly from reading the excellent and thorough monographs on the large Aquila
eagles overseas: The Black Eagle by Valerie Gargett (1990), The Golden Eagle by Jeff
Watson (1997) and The Spanish Imperial Eagle by Miguel Ferrer (2001). The idea
gelled initially as a similar book on the Wedge-tailed Eagle, to equal (to the extent
possible, given the relative levels of published research) these other books, and to
put the Wedge-tail on the world stage with its more famous congeners. Of course,
to attempt such a task I had to at least know the Wedge-tail well in the field, via a
detailed observational study of its complete breeding cycle from nest-building to
independence of juveniles. Incredibly, as at 2004, this still had not been done by
anyone, although there had been much science on quantified aspects of the eagle’s
diet and breeding ecology. So, in 2005 I started the field project but, out of the blue,
came Penny Olsen’s Wedge-tailed Eagle (CSIRO Publishing), released that year.
This event required a rethink of monograph plans, now broadened to cover the
other two Australian eagles – the Little Eagle and White-bellied Sea-Eagle. I have
to thank Penny, with her greater knowledge of such things, for relieving me of the
need to cover the background on Wedge-tails (e.g. Indigenous culture, European
discovery and early impressions). Free of the constraints of the ‘Australian Natural
History’ series, and with more published research by others, 10 years on there is
much more to say about all three species.
Naturally, to include Sea-Eagles and Little Eagles I had to conduct the first
behavioural studies from nest-building to juvenile independence on these species
(again, incredibly so in the 21st century) – Sea-Eagle in 2007 (not as complete as I
would have liked), and Little Eagle in 2006, 2008 and 2009 before finally getting a
fairly complete picture. It was a pleasure revisiting an old favourite from graduate
diploma days (Little Eagle in 1980), and seeing the recent growth in research by
others on these two species. I admit that I enrolled in that diploma, which required
a wildlife research project and thesis, just so I could study Little Eagles, after
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