The sulphur-crested cockatoo is usually
found in pairs or small parties. But in southern Australia they often congregate
in large flocks of up to a hundred noisy birds. These cockie mobs can get nasty
and attack trees, decks and houses in a controlled frenzy of destruction that
can go on for days.
By Ruth Beran
Sydney's
sulphur-crested cockatoo population has significantly increased since the '60s
Cockatoos are most destructive in spring when they
have an increased tendency to chew, especially in early spring and also in late
summer. Parent cockatoos are trying to build nests in early spring. In late
summer, the baby birds leave the nest and like teenagers start exploring their
environment and are more likely to destroy things.
Guess who's coming to dinner?
When the Balkins family bought western red cedar
for the exterior of the house they'd lived in for 17 years in Sydney's upper
North Shore they didn't expect nature to bite back.
Sue Balkin came home one day in 2001 to be told by
neighbours that 150 birds had "latched" onto the family house. "And they weren't
just chipping away at the timber," she says, "they were actually ripping the
timber off the home and the timber railing."
"It was a nightmare," says Sue Balkin. "It was
like that movie The Birds."
Why?
There are various theories amongst experts as to
why sulphur-crested cockatoos damage homes like the Balkin's. It seems we don't
know for sure why the cockies attack.
"They do it because of boredom or because there's
nothing else to do," says Associate Professor Lucio Filippich, an avian expert
at the University of Queensland. He also says that the cockatoos use their beaks
to wear them down so they don't overgrow.
Bird veterinarian Dr Michael Cannon agrees saying
that sulphur-crested cockatoos will chew to keep their beaks, an important tool
for everyday life, in good trim.
There are also other reasons he said. "We know
that in the wild they remove bark and they'll chew things up to try and find
grubs," he says. "But they are also naturally destructive, just chewing
things."
Kingsley Mead of Cockatoo Control, a company which
has developed an electric fencing to protect the rubber absorbers placed on the
rooves of houses with solar heated swimming pools, says that it is almost as if
the cockatoos "decide" to attack a property, leaving the one next door
untouched. "They're pretty smart codgers," he says.
Another reason is that soft woods like western red
cedar are easy to chew. "It's like soft butter to a cockatoo's bill," says Dion
Hobcroft of Taronga Park Zoo who has been watching birds since the age of seven.
"So it's probably quite pleasurable to chew into these soft
structures."
Dr Ross Perry, self-proclaimed grandfather of the
bird veterinarians, has a different theory. His view is that the sulphur-crested
cockatoos are adapting to the urban environment. "It is finding out what is
edible, what is not edible. Exploring that sort of thing," says Dr
Perry.
However, Dr Perry doesn't discount that the
sulphur-crested cockatoos could just be having a bit of fun.
"They're quite clowns, so they do have a huge
sense of fun. They're a highly intelligent animal."
Fact file:
When: Year round
Where: Coastal
Australia
Other info: Feeds:
Ground
Eats: Seeds, insect larvae, berries
Nest Habits: Tree
hole
Flight: Uneven flap-flap-glide, sometimes swoops to land
Habitat:
Most areas
Size: Approx 50 cm
Call: A loud raucous screech. Usually in
flocks.
Growing in number in Sydney
Originally the sulphur-crested cockatoo only
existed west of the Great Dividing Range. "Sulphur-crested cockatoos were
relatively uncommon in the '50s and '60s," says Geoff Ross from the National
Parks and Wildlife Service (NPWS).
Numbers of sulphur-crested cockatoos have
increased in Sydney since then and experts have various explanations as to why
this has occurred.
Ross says that anecdotal evidence would suggest
that sulphur-crested cockatoos and some other species of parrots are moving east
to places like Sydney, away from drought restricted areas.
"We don't have any hard data on this" says Ross,
"I am currently researching to try and find any correlations with increasing
population size associated with drought."
Dr Perry also believes that drought has an effect.
"I suspect weather change and agriculture have also made a large impact on the
bird population."
Unlike other species of cockatoo, such as the
endangered major mitchell cockatoo, sulphur-crested cockatoos have a natural
tendency to fly over wide open spaces and therefore adapt and migrate far more
readily over fields of monoculture crops which provide concentrated food
sources, says Dr Perry.
But there is another factor responsible for the
increase of birds in the Sydney area and that is, quite simply, the presence of
humans.
"Many cockatoos escape," says Dr Perry. "They're
being sold by the trappers to the Sydney market all the time in pet
shops."
Bird veterinarian Dr Michael Cannon agrees: "Man
has come and changed the environment and made it easier for the birds to
establish here," says Dr Cannon. "They've also brought them in as pets and
released them and the birds have found that they could stay."
One vengeful trapper
One controversial theory for the dramatic increase
in Sydney's sulphur crested cockatoos is that hundreds of sulphur-crested
cockatoos were released in Sydney in the 1980s by a disenfranchised bird trapper
who was lobbying government unsuccessfully in a petition to legally export
wild-trapped cockatoos.
Dr Perry believes that the trapper's rationale for
releasing these birds was: "so they would become a pest to the buildings and so
forth. So that they would create an anti-cockatoo lobby within the city
area."
He has no proof for this assertion however and
other experts believe that the story is just an urban myth.
Ironically, even if the trapper did not release
the birds in Sydney as claimed, or if the cockatoos he supposedly released did
not increase numbers, his aim of creating an urban pest appears to be coming to
fruition.
Keeping them away
There are several ways you can discourage birds
from attacking your property. Sulphur-crested cockatoos are a protected species,
so make sure you don't harm them!
One way is to string up a kite that looks like a
hawke or an eagle.
Another is to purchase a gel (from pest control
companies) that makes standing uncomfortable for the birds.
Or try stringing fishing line over the area that
needs protection, making it difficult for the birds to land.
Having a dog or cat in the yard can also
help.
Another option is to use a high-pressure hose.
"They are creatures that are aware and do recall traumatic incidents," says
Professor Filippich from the University of Queensland.
Asking them to leave
Once a flock of cockatoos have decided to attack
your house getting rid of them can be a bit tricky.
The Balkin family found that the birds weren't
frightened off easily. In fact, the cockatoos would wait on the electricity
wires outside the house till the family left, just like the birds in the
chilling scenes of Hitckcock's famous movie.
"There would have been a hundred lined up on the
wires, just waiting. It was very eerie," says Sue Balkin.
In the end the Balkin family could think of no
other solution than to cover the entire house with netting, purchased from the
local hardware store.
Ironically, the house resembled a bird cage. "And
we were living inside this cage," says Sue Balkin.
Even this did not stop the birds. "They were
cutting through the netting and they were getting back in again," says Sue
Balkin.
"We ended up buying a cap gun and every time they
came towards the house, we would use the cap gun."
One person had to stay at home on 'cockatoo duty'.
Eventually the birds moved on. However, once they stopped attacking the Balkins
home, they started destroying other houses in the area.
For really severe problems, Geoff Ross from the
National Parks and Wildlife Service (NPWS) recommends getting an occupier's
licence. This licence is issued by NPWS and costs nothing. "An occupier's
licence allows the landholder to remove wildlife without being prosecuted," says
Ross.
Final lesson
One lesson Sue Balkin has learnt is that despite
their own pearly white plumage, sulphur-crested cockatoos do not like the colour
white.
"My next door neighbour was never attacked. She's
got white railing on her timber," she explains. "The green netting I originally
put on the house didn't deter them but once I bought the white netting, they
stopped."
Maybe if a re-make of Hitchcock's masterpiece is
ever considered, someone should suggest using sulphur-crested cockatoos. At
least then, art could imitate life, instead of the other way round.
http://www.abc.net.au/science/articles/2003/10/09/2045456.htm
