I am of course just guessing but it does seem odd to have so few
Wedge-tailed and Flesh-footed Shearwaters too. Certainly, something is
very different this year. 1000's of Short-tailed Shearwaters so hungry they
were landing on the boat off Sydney on Friday is quite an experience. But
as Chris points out there could be a positive spin to this. Perhaps it
would be good to find out if there is anything unusual on the breeding
grounds?
If the shearwaters are starving then how healthy are the less common
species? Furthermore where are they right now?
Cheers, Tony
-----Original Message-----
From:
On Behalf Of Chris Corben
Sent: Sunday, 3 November 2013 12:33 AM
To:
Subject: Mottled Petrel off Sunshine Coast
I have been following the Short-tailed Shearwater story with interest. I
love these birds! I certainly bear them no ill-will.
But lets face it - if millions didn't die each year, the planet would soon
become covered in them. In reality, that's not going to happen, because all
sorts of things tend to keep populations in check, unless you are like
humans, and clever enough to avoid population stability.
Every year, millions of STSWs migrate down the east coast of Australia, with
the first year birds coming through about now. Every year, huge numbers of
them die during this time and end up on beaches, alarming people who don't
understand biology. Some years we see more dead than other years, and some
years we see huge wrecks. But what does a wreck mean?
There are all sorts of things a wreck could mean. I'll suggest a few.
1) Recent breeding seasons have been unusually productive
2) They had an extra good time in their wintering range, so there are more
than usual still alive now
3) Conditions have resulted in more of them flying where we can see them, so
we see more dying
4) They are experiencing very tough conditions and there will be far fewer
breeding next season as a result.
Of these, only the last is anything to worry about. How do you distinguish
between these (and other) possibilities? You need trained biologists who
understand population dynamics and the specifics of how they relate to
STSWs, and you need them to have access to data collected for meaningful
monitoring of the species.
Witnessing a wreck is a fascinating, and maybe scary thing, but
understanding what it means requires actual science, not knee-jerk
reactions.
With regard to what Greg and others have noted recently, if there are
unusually large numbers present in the near off-shore waters, then you would
expect to see unusually large numbers dying. Still doesn't give any
indication of whether or not the mortality is abnormal, or of any
consequence to the species.
Cheers, Chris.
On 11/02/2013 03:37 AM, Greg Roberts wrote:
> Short-tailed Shearwaters were in unusually large numbers.
>
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