Picture source courtesty

Many Australian birds of prey rely heavily on rabbits as a food source.

Will Australian birds of prey such as the Wedge-tail eagle who relies on rabbits for 95% of its food source in some areas, cease to breed and decline in numbers over time?

Senator Robert Hill (Minister for the Environment) read the draft Environmental Impact Statement that states that there is a close relationship between many of the Australian Birds of Prey and feral rabbits (in fact in some areas the European rabbit comprises 95% of the diet of the wedge-tailed eagle). Senator Robert Hill and the Australian authorities chose NOT TO AUTHORIZE the preparation of a full Environmental Impact Statement and skipped this crucial step in deciding to allow the declaration of RHD as a biological control in Australia and condoning the subsequent ongoing deliberate spread of RHD. It was stated in the draft EIS that some Australian birds of prey may decline or cease to breed as a result of the decrease in rabbit numbers and yet a full study into the survival of these species was never commissioned.

The Australian authorities have funded a bird of prey watch to monitor the numbers of birds of prey till the year 2000. (The bird of prey watch relies mostly on volunteers observations). How irresponsible have officials been in ignoring the plight of the unique Australian birds of prey? Only time will tell. One raptor organisation has reported farmers saying that if the wedge-tail eagle tries to take lambs in desperation because of lack of rabbits, they will be shot.

How will the decline of raptors effect the web of life in Australia? Raptors have an important role in the web of life. Raptors help keep down the numbers of rabbits and mice in the wild and clean up dead carcasses. Raptors have a right to exist and their survival deserves as much consideration as that of any other valued species.

Unfortunately watching the numbers of birds of prey (declining?) until the year 2000 will not help save them. It brings to mind an analogy of Nero fiddling while Rome burns. (taking into account the fact that authorities are deliberately out in the domain of the raptors spreading RHD while encouraging the monitoring of the number of raptors?). Will more wedge-tailed eagles die trying to eat roadkill victims (eg kangaroos) because they are starving to death? (they may then be hit by cars themselves as has been reported in the press)

According to the RAOU (Royal Australasian Ornithological Society):

The diurnal birds of prey are top predators which, together with their relatively high visibility and their known sensitivity to environmental conditions, makes them ideal 'indicator species' for environmental change. Although introduced to Australia the rabbit is now an important component in the diets of 11 of Australia's 24 species of diurnal raptor. Thus the release of the rabbit calicivirus within Australia last year, and the subsequent massive decrease in rabbit numbers over large areas, has serious implications for a number of our raptor species. It is likely that the spread of this rabbit disease will result in declines in some raptor populations, with decreased breeding success and some degree of prey switching.

Fortunately, the RAOU and the Australasian Raptor Association (ARA) conducted a nation-wide survey of the abundance and distribution of Australia's birds of prey - the "BOP Watch" project - between 1986 and 1990, before the release of rabbit calicivirus. BOP Watch involved bird enthusiasts acting as volunteer observers by identifying and counting raptors while driving along rural roads at normal speeds. This information, together with the route travelled, time taken and other variables was recorded on a simple, standard datasheet. The project collected 26,516 datasheets from 271 volunteer observers, and now provides a valuable source of information on the status of our birds of prey shortly before the release of rabbit calicivirus.

The Federal Government has made funds available through the Australian Nature Conservation Agency to enable the RAOU and the ARA to conduct a second, four-year BOP Watch in order to collect comparable data following the release of rabbit calicivirus. This project will use the same techniques as the first BOP Watch, and will run from July 1996 to, hopefully, June 2000. The information collected during this second BOP Watch Project will be of great importance as it will allow us to accurately assess the impact of the Rabbit Calicivirus Disease on our native birds of prey.

BOP Watch needs the assistance of competent birders from throughout Australia to carry out the necessary roadside counts of our birds of prey. The methods used are not difficult or time consuming and people of all ages and abilities can become involved, provided they are able to correctly identify birds of prey. BOP Watch provides an opportunity to become involved in a worthwhile, community-based research project while keeping occupied during long drives.

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Big Wedge-tailed Eagles, deprived of their staple diet by the Rabbit Calicivirus Disease, appear to be causing increasing damage to vehicles in the Outback. The release of the Rabbit Calicivirus has reduced rabbit numbers in some areas by up to 95 per cent. Older birds which previously got their food by hunting rabbits have turned to dining on corpses of animals killed by vehicles. Reports are increasing of windscreens smashed and steel roofs torn from cars by eagles trying to flee from their meals as vehicles approach on the Barrier Highway out of Broken Hill in New South Wales. In one case a Broken Hill baker's van hit an eagle that ploughed straight through the window. The driver fled as the eagle tore the cab apart looking for a way out. One car windscreen repairer said "If you're cruising down the road and see a big wedgie sitting on a carcass, slow down because they make a mess. Some people collect them in the grills, pull them out and just drive on - but they're the lucky ones." Brisbane ornithologist Peter Slater said cars would have to be travelling fast to have their windscreens broken by the birds, which can have wingspans of up to 2.5 m and weigh 5 kg. Mr Slater said Wedge-tailed eagles had always feasted on roadkill and it was hard to believe there had yet been a change in the numbers along the roads. The calicivirus would have an effect because rabbit had been their main prey for a long time. "They are going to have to hunt something else and possibly more will come to kills on the road," he said.

The West Australian
January 13 1997

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Tasmania's endangered Wedge-tailed Eagle is likely to swoop on other prey if the rabbit population declines due to Rabbit Calicivirus Disease. Australasian Raptor Association President Mark Holdsworth said yesterday there was a healthy population of small animals in Tasmania that made up most of the diet for the majestic birds. Unlike mainland Australia, where many small mammals have dwindled in numbers because of introduced predators such as the fox and feral cats, Tasmania still has a bountiful supply of wallabies, possums, bettongs, quolls, potoroos, and echidnas. Interstate reports indicate Wedge-tailed Eagles are relying on road-kills of native animals because the calicivirus has reduced the rabbits. Mr Holdsworth said "wedge-tails" predominantly ate dead animals. "All birds of prey only breed and only produce young if they have a good food source but we're fairly confident there are not going to be any birds of prey endangered because of the rabbit calicivirus," he said. Tasmanian Wedge-tailed Eagles, a sub-species of the mainland bird, were threatened more by human persecution and insecurity of nest sites. It is estimated there are about 95 breeding pairs in the state and between 700 to 900 individuals. Mr Holdsworth said that monitoring would begin of the nesting sites of two other birds of prey in the state, the Grey Goshawk and the Marsh Harrier. "Both of these birds had a high reliance on rabbits in localised areas," he said. Also yesterday, Tasmanian Farmers and Graziers Association President, John Gee said with the calicivirus in the state it was time to control feral cats. The outbreak of the disease should lead to a massive drop in rabbit numbers and a corresponding decrease in feral cats. "With a co-ordinated approach to both rabbits caused by the calicivirus, and feral cats we may well be rid of the worst pests in our environment," he said.

The Mercury 15/1/97

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A Western Australian expert on raptors, Mr Phil Pain, recently warned of neglect in determining what impact the rabbit calicivirus disease will have on native birds of prey. Ornithologists are also questioning the lack of funding, study and research into the future survival of some of Australia's unique birds of prey. Many species of birds of prey will be severely affected if rabbit numbers decline dramatically. The Wedge-tailed Eagle Aquila audax could cease to breed. Other species at risk reportedly include the Little Eagle Hieraaetus morphnoides, Black Kite Milvus migrans, Spotted Harrier Circus assimilis and certain goshawks and falcons. Birds fanciers come from Europe to see our birds of prey, to the benefit of the ecotourism industry. Authorities in charge of the agricultural-backed program to wipe out rabbits with calicivirus do not fully understand the role the rabbit has assumed in the food chain of Australian predatory animals in the last hundred years. I do not believe that any studies have been undertaken to investigate whether native animals could replace the rabbit as a source of food for raptors. In any case, land clearing and poor farming techniques including soil degradation and overgrazing have contributed to the demise of our native small mammal species. Survival in an altered landscape as well as other factors will influence the ability of small mammals to reproduce in the numbers necessary to ensure the survival of our noble hunting species. In time our birds of prey will be named on the list of endangered species, as have so many other species.

The Australian Letters to the Editor 2/7/1996

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Starvation diet
by Rachel Nowak
New Scientist 31st October 1998
Raptors are paying the price as Australia wins the war against rabbits

THE deadly calicivirus that has devastated Australia's rabbits may be having a knock-on effect on indigenous wildlife. Wedgetailed eagles (Aquila audax) have not bred for the past three years in the Strzelecki Creek region of South Australia, according to a study from the Australasian Raptor Society and the state's government. Rabbits had become the food of choice for many birds of prey so the researchers suspect that the failures are due to food shortages.

The calicivirus reached the mainland in 1995 from Wardang Island, off South Australia, where it was being tested as a method of controlling rabbit numbers. It spread quickly across the country, decimating rabbit populations. But from the start, conservationists have worried that either the virus itself, or the shortage of rabbits for food, would affect Australia's natural fauna.

Those fears now appear to be being realised-although to date there is no evidence that any species is seriously threatened. The overall abundance of birds of prey has declined in areas affected by the calicivirus, according to Birds Australia, an organisation that uses volunteers to estimate bird populations. Brown falcons (Falco berigora) are the hardest hit, with the number of sightings down by half over large swathes of temperate Australia.

Curiously, the number of roadside sightings of wedge-tailed eagles has doubled during the summers since the introduction of the virus. But that may be due to changes in the bird's behaviour bought about by hunger, claims Will Steele, a project officer with Birds Australia in Melbourne. He suspects that the eagles are being driven to feed on road kills.

Roger Pech, a population ecologist in Canberra with the Wildlife and Ecology division of CSIRO, Australia's national research organisation, is sceptical of the Birds Australia data. For long-lived raptors it should be too early to see the effects of the reduction in rabbits, he says. But breeding success could be hit more quickly. CSIRO's own studies of wedge-tails around Lake Burrendong in New South Wales have so far been inconclusive. In the first year following the virus outbreak, most of the eagles bred successfully. This year however, breeding activity has fallen markedly. Another CSIRO study in the same region has found early indications that more brushtail possums, a native species, are being eaten by foxes and feral cats since the rabbit decline. "In the short term, it's a real concern that feral cats and foxes will eat the indigenous species," says Pech. But the reduction in rabbits may in the long term be beneficial to native animals. In the Journal of Applied Ecology (vol 35, p 434), Pech describes a model of prey-predator interactions which predicts that the lack of rabbits will eventually lead to a reduction in the number of introduced predators such as foxes and feral cats.


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The Australian Newspaper
Weekend - January 1-2 /2000

Threatened Eagles dining out on a highway to hell.

Nicolas Rothwell

The monarch of central Australian skies, the wedge-tailed eagle, is facing a new man made threat to its numbers, - but a simple albeit unpleasant solution is at hand.

Keepers at the Desert Park in Alice Springs, where the eagles and other birds of prey fly free, have been tracking the decline of the eagle population over recent months.

Wedge-tailed eagles, it is now clear, are the inadvertent casualties of modern Australia's greatest biological triumph: the controlled release of rabbit calicivirus, which has all but eradicated the outback's wild rabbits.

One result has been the dramatic recovery of the Centralian desert lands since the introduction of the disease in 1995. But another has been the disappearance of the wedge-tailed eagle's favourite food source.

"The rabbits are gone," says the Desert Park's eagle keeper, Jason Bell. "There hasn't been enough time yet for the smaller native marsupial species to return, so rather than the wedge-tailed eagles hunting far away in the desert, they are feeding out here on the highways on road kill and being hit by cars and trucks along the road."

Raptor specialists are unsure how serious the crisis may be, but anecdotal evidence is bleak. Bell travelled through the Barkley Tableland a year ago and counted 12 dead eagles by the roadside over five days.

"The intelligence of these birds is devoted mainly to finding and catching their food, not to avoiding cars," Bell laments.

Bell and fellow keeper David Constanzo know and admire their eagles but - in conformity with the Desert Park's rather modern philosophy - they neither handle them in public nor do they treat them as pampered pets.

From Bell's distinctly practical acquaintance with the wedge-tailed world, comes a very pragmatic approach to their plight.

"These are very adaptable birds," Bell says, "they are generalist hunters and the highway is their restaurant of choice these days. They are eating there so lets rearrange the tables."

His predcription then for saving wedge-tailed lives? Next time you drive on an inland highway and pass some road kill, a bloated cattle carcass, or a kangaroo, stop the car and drag the malodorous morsel 20m away from the bitumen into the bush, where the birds can feed in discreet and tranquil safety.


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To:The Editor,
Australian Newspaper

Dear Editor,

The article concerning the increase in numbers of Australian wedge-tailed eagles being hit by cars and trucks as they feed on road kills (1/1/2000) is cause for concern. The short term solution of moving the carcases of road-kill animal victims away from the edge of roads so the wedge-tail diners are not hit by cars as they feed is most admirable. However, there are some inaccuracies and omissions in the rest of this article. Firstly, the article states that the wedge-tails are "are the inadvertent casualties of modern Australia's greatest biological triumph: the controlled release of rabbit calicivirus" and also mentioned is the "the introduction of the disease in 1995". Rather than being "introduced", RCD (correct name Viral Haemorrhagic Disease of Rabbits or RVHD) escaped from Wardang Island in 1995 and spread across Australia by epidemic before the official release of the virus in 1996. Prior to the legalisation of RHDV as a biological control agent, a draft Environmental Impact Statement written by B.J. Coman recognised that the demise of the rabbit in Australia may have a severe effect on at least 11 species of diurnal birds of prey including the wedge-tailed eagle. New Scientist magazine published an article (31/10/98) indicating that wedge-tailed eagles (Aquila audax) had not bred for the past three years in the Strzelecki Creek region of South Australia (a premier breeding ground for many birds of prey).

While some scientists are pleased at the regeneration of some bushland in various parts of Australia due to the absence of rabbits, there are still grave concerns held by other scientists that RVHD may yet be shown to affect the health and welfare of other animals and humans. Australian authorities have not proven RVHD to be species specific to rabbits and Australian authorities were not able to contain the disease to Wardang island from where RVHD escaped in 1995. The escape of RVHD was not a triumph but rather a failure by Australian scientists to contain a little understood haemorrhagic disease of mammals to open air testing on Wardang island. The demise of rabbits and wedge-tailed eagles due to human interference in some areas of Australia indicates that humankind continues to misunderstand the fragile balance that exists in the Australian native food web. Poor farming practices and the introduction and grazing of hard hoofed European cattle and sheep have caused much damage to the Australian landscape and have also contributed to the demise of many Australian native species . The further introduction and farming of other exotic crops and animals in our near past indicates that the white European settler in Australia has learned little from past mistakes and the demise of large numbers of birds of prey should not be surprising at all given our ongoing collective mismanagement of this fragile continent.

Kind regards,

Marguerite Wegner

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"A Talk with Mark Holdsworth, President of the ARA & Observations on Birds of Prey in Tasmania"

After many years of waiting and procrastinating, my wife and I finally got round to fulfilling our promise to visit our Tasmanian friends. Via Frankfurt, Bangkok, Singapore, Sydney, and Melbourne we reached the island of Tasmania and arrived in its capital Hobart.

In our drives and bush walks which criss-crossed the state we observed so many birds of prey that we were unanimous that here, the world was in its natural order. Unfortunately this was not so, as Mark Holdsworth later told us. I gave Mark an overview of the German birds of prey situation as far as my knowledge extended. He pointed out to me that in Australia (including Tasmania) the taking of birds of prey for falconry purposes is illegal, and that a reversal of this is unthinkable.

It is difficult for Australian raptor proponents to reach and teach all people to tolerate raptors. Eagles have been protected for 10 years in every state, but not so long ago it was still possible to get a licence in Western Australia to shoot an eagle. The reported number of eagles shot to the present day of 2 million is shocking. It is also difficult to explain to farmers that the Wedge-tailed Eagle Aquila audax is not a sheep or a lamb killer. Many lambs die of weakness after birth and then become the target of the introduced fox or feral dogs. In Tasmania, there are no foxes, and eagles seen feeding on dead lambs have been in most cases scavenging. A study has shown that lambs are less than one percent of an eagles' prey. A further study points out that a breeding pair takes 800 rabbits in a year. We know that one pair of rabbits can potentially produce the enormous number of 500000 offspring in 5 years. One can imagine how much grass the rabbits get through and how much help the eagles are to farmers in maintaining their pastures. The rabbit, imported from England in 1859, gives the Australian farmer a yearly damage bill of well over 100 million dollars. The population of Wedge-tailed Eagles in Tasmania is estimated to be about 200 pairs with about half breeding. I asked Mark how raptors in Tasmania are affected by electrical cables. He explained that each year many birds of prey come to grief on powerlines, resulting in injury or death. Raptor enthusiasts in cooperation with the Hydro Electric Commission have an objective to modify 20 000 electrical poles in such a way that birds cannot be electrocuted.

Injured raptors that cannot be rehabilitated go to Wildlife Parks (small private zoos which are well controlled, part of Mark's work). At some parks' entrances one can read that some wildlife, including raptors, held there cannot be rehabilitated. Mark spoke with regret of the small number of people currently involved in raptor rehabilitation in Tasmania and the small number of ARA members given the size of Australia (about 400 in 16,000,000).

The status of many raptors in Tasmania is better than on the Australian mainland because there the introduced Red Fox provides much competition. The fox can achieve large numbers and when rabbit numbers reduce due to the myxomatosis virus, foxes can prey-switch and have a devastating effect on native wildlife. Such is an example of what we gleaned from Mark, who is a mine of interesting information on the birds of prey situation in that other end of the world and with whom I hope to maintain and intensify contact.

For minutes we observed Wedge-tailed Eagles in their marvellous flight. The sheep grazing underneath them were not at all disturbed. Only the ravens were fussed about the joint habitat occupancy. However, the eagles did not allow them to make an impression and continued their circling unabated. Before our eyes an eagle grabbed a rabbit and flew a kilometre away with its prey. We also observed a White-bellied Sea-Eagle Haliaeetus leucogaster over the sea. Twice we saw the Brown Goshawk Accipiter fasciatus, once catching prey. Another time we saw a collared sparrowhawk A. cirrhocephalus hassling a Swamp Harrier Circus approximans quite close to us. Twice we saw the fast flight of the Peregrine Falcon Falco peregrinus which is fairly common in Tasmania. Many times we observed the Australian Hobby F. Longipennis flash past, crying shrilly in the blue evening sky with its partner. But, by far the largest numbers observed were of the Brown Falcon F. berigora, twice seen catching prey in a field. Sensational for me was a sighting of the white variety of the Grey Goshawk A. novaehollandiae, glowing white and flying 50 metres above the wild forest canopy.

It was wonderful to be able to experience all these moments in the wild. Many moments we were able to capture with the video camera, but the actual meeting with the birds of prey in the wild will remain for us an unforgettable experience.

Our flight out became a real avian experience. We will not forget the sight of thousands of Black Swan Cygnus atratus which still occur in Tasmania in abundance, or the Laughing Kookaburra Dacelo novaeguineae (also called "laughing Hans"), the parrots and the many song birds of which I could only identify a few. But our main interest was obviously the raptors.

GERHARD KRUPKA (GERM) Orden Deutscher Falkoniere No.9, 1995


"Local Newspaper photo from around 1935, article read:

" More than one big Eagle has bitten the dust in this district during the past few weeks, but not many of them were larger than the one George Pardey (of Cowra) shot at Neila on Sunday. From wing tip to wing tip it measured 7 foot 2 inches." 220cm

This recently discovered Photograph from the 1930's features Harold (Jack) White and his photographer friend George Pardey of Cowra NSW Australia. This photograph highlights the unfair persecution Wedge tail Eagles suffered during the last century. In one year alone, it was estimated that 30,000 Wedge tail Eagles were killed. The Eagles were blamed for killing livestock, yet most were only feeding on sick or injured animals. This fully mature Adult had a wing span of 220cm.

Harold White is the Grand Father of Birdphotos Photographer Greg Holland"


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