I'm with Andrew Stafford, Chris Brandis, Alan Morris and some others
in not being convinced that the shearwater mortality is necessarily
anything out of the ordinary. There are more dying this year by all
accounts, but I remember last year too there was a discussion about large
numbers of beachwashed birds.
Anyway, here are a couple of sums. This spring the rate of Short-tails
passing Maroubra, Sydney, per hour (so far) is three times as high as the
second highest year (1997) in the past five years, and that's based on
about 350,000 Short-tails counted in the six years. In the other years
(1995, 1996, 1998, 1999) the hourly rate of birds passing the coast was a
lot lower again. So, with many more birds close inshore, it's not
surprising that many more are getting washed up.
Next sum: given that there are two, maybe three times as many Short-tailed
Shearwaters in Australia as humans, and a couple of hundred thousand humans
die every year (I think), a few ten thousand, even hundred thousand of dead
shearwaters does not mean they are in serious trouble (except the dead
ones). That doesn't mean it's not distressing, but if we're talking about
species survival, I'd have thought they can take it. As Alan pointed out,
they have in the previous years when they've been washed up in big numbers.
Finally, after the massive passage in the middle of October, the numbers of
beachwashed birds here at Maroubra Beach at least has dropped off a lot in
the last ten days or so, and the hordes of thousands, sometimes tens of
thousands, of shearwaters have continued to fly past southwards. Most are
not dying. There are a lot of other Australian birds (all other Australian
birds?) that are in much greater danger of extinction.
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