Sunday, March 04, 2007

Conservation on Macquarie Island

An interesting article in The Age today claims that Tasmanian and Federal Governments are squabbling while the biodiversity-rich Macquarie Island is threatened by a rat and, particularly, a rabbit plague. Macquarie is halfway between Australia and Antarctica and is part of Tasmania.

Macquarie is classified as a world heritage site - partly for geological reasons but also because of the plants and species there. It is an important habitat for marine mammals and about 3.5 million seabirds arrive annually there to breed. Many are penguins - it is an important roosting habitat for King penguins - but there are also pelagic rarities - the Light-mantled sooty albatross (pictured above) is one. The Age article describes the LMSA as threatened with extinction - this is an exaggeration - though its numbers have come under intense pressure because of predation of chicks by ferals and because of long-line fishing.

The World Heritage Bureau is investigating Australia's management of the island.

The sad story of Macquarie is due first to the initial daft decision to introduce pest species there and then by a well-intentioned, though mistaken, decision to eliminate only one of the introduced species - the despicable common cat (Felis catus). With the cats gone there was an explosion in the rat and rabbit population. Yes, conservation biology is complicated - recall the cane toad story!

Who was responsible? Well the Commonwealth Government claimed credit for the cat elimination program which it funded from 1997- 2001. This does seem to implicate them a bit. They have offered half the $16.9 million required to address the rat/rabbit program but the Tasmanian Government refuses to put in the other half so nothing is being done. Really the impass makes you wonder why such important issues are being decided by State politicians.

The WWF has organised a online petition here to persuade the giovernmernt to take decisive action. Please consider signing it.


Kerryn Goldsworthy said...

Spot on, about the cat control unintentionally producing the explosion in the rat and rabbit population. I was just talking tonight to a friend who spent a year in Antarctica a while back and he said exactly the same thing, right up to the cane toad comparison.

hc said...

Pavlov, I like the cat 'personality' but would never own one as I am suspicious of their impact on Australian bird and mammal populations. There actually isn't that much research on this issue - the little that has been does finds cats are destructive - particularly for mammals - but with hunting powers that are exaggerated.

In urban areas, where wildlife has been depleted, cats presumably hunt mainly introduced bird species such as mynas. Of course in such areas cats should be desexed, belled and not allowed to roam at night. Baits should be laid in urban areas to catch wandering offenders - a couple of aspirin in an open tin of tuna will do the trick.

Cats should not be kept next to nature reserves or in the bush. Again the tuna and aspirin technique will do the trick.

On Macquarie there are a host of feral introduced species (cats, rats, rabbits). It was an act of environmental vandalism to introduce them there.

But, having done so, eliminating the cats alone causes damage. This is not a blanket case for allowing wild cat populations to flourish. To the contrary it suggests that removing pest species should be carried out on a comprehensive basis.

Kerryn Goldsworthy said...

I agree with all of that, Harry. I'm a sensible all-animal lover, not the sort of mad cat lady that gives ailurophiles a bad name, so management of all fauna seems to me the ideal thing, in the name of biodiversity. (My own two cats live permanently inside, by the way, at least until such time as I can get round to building a secure cat run, for exactly those reasons.)

In the case of Macquarie Island, you really would think that a little forward planning would have been built in to biological control, given the cane toad experience.