Thursday, August 29, 2019

Threats to Tasmania's Raptors

https://upload.wikimedia.org/wikipedia/commons/thumb/0/01/Tyto_novaehollandiae_castanops_male_2_-_Port_Arthur.jpg/1024px-Tyto_novaehollandiae_castanops_male_2_-_Port_Arthur.jpg
Vulnerable - Tasmania's Masked Owl 
 Image - JJ Harrison (https://www.jjharrison.com.au/) per wiki under CC3


Since writing about raptors a couple of weeks ago, I have talked to wildlife expert and consultant Nick Mooney, who has had fifty years of experience with Tasmania’s native species focusing on birds of prey or raptors. The good news he said, was that the large raptors such as the Wedge – tailed Eagle and the White-bellied Sea-eagle do seem to be holding their own, possibly even increasing in areas where devils have drastically declined, thus freeing up much carrion. Changes in attitude and laws leading to decreased persecution have also helped. Sea-eagles may have also benefited from the many new artificial lakes and ponds. 

However, he warns, this could change rapidly if the thirteen wind farms proposed for Tasmania go ahead, together with all the supporting power lines and infrastructure. As the Spanish example with regard to Bonelli’s Eagle has shown, detailed surveys, tracking routes and hunting ranges and subsequently siting and designing for least impact, will be of utmost importance, but such strategic surveying and planning simply does not occur in Tasmania. The most that happens is that turbines are located 1 km from eagle nests but this 1 km is a distance borrowed from forestry advice on reducing disturbance and has no rational founding whatsoever in minimising physical risk from turbine blades.

Windfarm advocates routinely dismiss the birds killed at windfarms as insignificant compared to what cats kill but this pitch is mischievous he says, because the reality is chalk and cheese. Sure, cats kill more birds than windfarms do, but those numbers are highly misleading since cats usually kill many small birds, birds which can usually breed their way out of problems from increased mortality. But large raptors (which are amongst the rarest of birds) are wildly over - represented in the windfarm kill statistics and these birds are not able to breed their way out of problems from increased mortality. Windfarms are, worldwide, an increasing problem for large raptors, says Nick. 

Because the windfarm issue is well known and gets considerable publicity, Nick is far more concerned about our smaller raptors that get overlooked because they are relatively common – the Tasmanian Mopoke (aka Southern Boobook) and particularly, the Brown Falcon.  Judging by the numbers of the latter brought injured into refuges or found dead on his extensive road counts over decades, he estimates that they are down to 20% of their former strength. 

This may be from decreased breeding and/or increased mortality. It seems that the days of seeing scores of juveniles feeding on crickets and grasshoppers in single stubble fields in late summer are long gone. The main cause of injury of those found on roadsides seems to be collisions with vehicles but an old problem seems to be more apparent now; secondary poisoning, usually as a result of eating poisoned rats and mice.  

 The main reason for this appears to be intensifying agriculture and the use of anti-coagulant rodenticides, the newer (‘second generation’) ones which kill in ONE application, rather the older type (‘first generation’) of anti- coagulants which took multiple doses.The weaker older poisons, allowed more birds to recover after ingesting poisoned prey..  This issue has long been known but got much press a few years ago when Parks and Wildlife officers on Macquarie Island sought to remove introduced rats and mice to enable native species to recover. Previous eradication efforts had not much affected native bird populations, but the new products certainly did and populations took some years to recover from the successful eradication of rats, mice and rabbits (a remarkable achievement in itself). 

As Nick says, sufficient numbers of raptors on or around a property to begin with, would help prevent the rodent problem peaking in the first place – predators often buffer the population ‘booms’ in prey but they have to be  in high numbers to do so. Sadly, right now, no one knows how our prime avian rodent catchers – the Masked Owls, Tasmanian Mopokes and Tawny Frogmouths are faring. They are secretive creatures that hunt mostly at night and are not easily surveyed without tracking equipment.

As in many a Third World country, few comprehensive surveys are done in Tasmania and sophisticated conservation has increasingly taken a backseat to economic development, seemingly at any cost. While I am all in favour of renewable energy, at this stage, it doesn’t appear that Tasmanians will benefit much from the proposed developments which may in fact compete with our sales of hydro -electricity, while tourism, including wildlife tourism and our fine food and wine industry which trade on our “pristine” environment and already bring in far more, may well suffer. 
What about jobs? With the first large windfarm in the Central Highlands almost at the commission stage, it would appear that  the project will only employ about TWO Tasmanians to dig a couple of holes and pour a bit of concrete.
Just because the proposed developments are out of sight of a clamouring populace, doesn’t mean we should let them pass without rigorous assessment. 







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