Threat of invasive species
2007-11-30 20:30
Port Louis - Three centuries after
the dodo's demise, the rich plant and animal life of Mauritius
is still under threat, this time from exploding populations of
non-native species such as Chinese guavas and Malagasy geckos.
Conservationists on the Indian Ocean island that was once
home to the flightless dodo bird say predators like rats and
monkeys are being joined at accelerating pace by new arrivals
like the giant Madagascar day gecko which first came as a pet.
"From there, it has either been released or escaped. The
population is just exploding at the moment," said Nik Cole, a
reptile expert with the Mauritian Wildlife Foundation.
The Malagasy species is a major threat to native reptiles
such as the Mauritian day gecko, he told Reuters.
Other recent arrivals include the apple snail and the
red-eared terrapin.
Plants at risk too
On the small Mauritian island of Rodrigues, scientists have
noticed the disappearance of native centipedes since the
arrival
less than 10 years ago of the Indian musk shrew.
"With many exotic introductions, you don't notice an impact
until their numbers reach a certain level," Cole said, echoing
the warnings of many other local environmentalists.
The exotic imported animals, plants and even germs
out-compete or hunt native Mauritian species which evolved in a
less competitive environment over millions of years.
Plants are also at risk from aggressive arrivals such as
the
Chinese guava, the Malagasy traveller's palm and hiptage which
often smother the Mauritian trees.
"Most of the plants in Mauritius that are rare, are rare
because of invasive species," Vikash Tatayah, Conservation
Manager at the Mauritian Wildlife Foundation, said by phone.
His organisation has had notable success in saving
endangered birds such as the echo parakeet, the pink pigeon,
and
the Mauritius kestrel, down to just four known birds in 1974,
though the local broad-billed and grey parrots are extinct.
In the case of the green-feathered echo parakeet, ravaged
by
rats, monkeys and the loss of forests, conservationists swap
eggs or chicks between mother birds to maximise their chance of
survival, wrap plastic round tree trunks to deter climbing
rats,
and deepen holes in trunks to hide nests from monkeys.
Scientists say the world has suffered five mass extinctions
in its history and a sixth is looming, linked to human
activity.
Small islands like Mauritius, evolving at a distance from
the larger landmasses, often developed a rich and unique
biodiversity - but in modern times find their flora and fauna
threatened with extinction as a result of the growth of global
travel and trade.