Seabird wrecks have always fascinated me. On the face of it, there simply
isn't any evidence that they are a bad sign, or good or anything else.
A lot of STSW being cast up this time of year is an annual event, as the
young birds move through. If there are abnormally large numbers of dead
birds, this could be a good sign - an indication of an extra good last
breeding season, or perhaps unusually mild conditions in the far north,
either way meaning there are far more birds around than most years to die.
Or it could be completely meaningless - typical annual mortality being more
visible than usual because the birds have come through closer to the coast
than they do most years. I gather more than usual have been seen alive, so
this would be my null hypothesis, unless there is good evidence otherwise.
Or it could be that conditions lately have been abnormally rough for the
young birds, and the net effect might be that last years crop of young has
largely failed.
Without a lot of evidence, there just isn't any way to distinguish between
these, and other possibilities. So mortality, per se, could just as well be
a good sign as a bad sign.
Unpleasant though such mortality might be to humans, you have to remember
that if most of the baby shearwaters didn't die each year, the whole planet
would be covered by the furry little critters.
Chris Corben,
Birding-Aus is on the Web at
www.shc.melb.catholic.edu.au/home/birding/index.html
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