Hi Chris,
I do understand and appreciate your comment. I just would like to raise that
there is a misunderstanding. 400 Short-tailed Shearwaters during the Mooloolaba
pelagic, 219 STSWs during the Southport pelagic, 100s off Sydney and even 5000
off Wollongong are NOT 'unusually large numbers' in general. Unusual was:
(1) The behaviour of the Short-tailed Shearwaters, which were very hungry and
remained around the boats eating as much chum as they could. So, there were
'unusually large numbers' near the boats only. Normally (in other years) we get
similar or mostly higher numbers streaming south in flocks and not stopping for
our chum. This confirms that lots of STSWs are starving and eventually dying. I
agree that this doesn't tell us much about the cause of the wreck.
(2) The numbers of Wedge-tailed and Flesh-footed Shearwaters were unusually low
on all mentioned east coast pelagics. This may indicate that something strange
is going on out there.
I agree, that professional population dynamic studies need to be undertaken to
find out, which of the four factors mentioned by you in your e-mail below
caused this year's large wreck. But I also believe, that the 'snapshot' data
from our pelagics (especially the combination of starving/dying STSWs and the
lack of WTSWs and FFSWs) could add some descriptive information to the
population dynamic data that may be generated or maybe even trigger new
population dynamic studies, which can be significantly delayed due to the fact
that funding needs to be applied for.
Best wishes,
Nikolas
----------------
Nikolas Haass
Brisbane, QLD
________________________________
From: Chris Corben <>
To:
Sent: Saturday, November 2, 2013 11:32 PM
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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