Black-winged Petrel, White Tern, False Killer and more: SOSSA pelagic of

To: Chris Corben <>, "" <>, Paul Walbridge <>, Jeff Davies <>, Alan Gillanders <>, Raja Stephenson <>
Subject: Black-winged Petrel, White Tern, False Killer and more: SOSSA pelagic off Wollongong NSW
From: Nikolas Haass <>
Date: Mon, 30 Jan 2012 01:33:40 -0800 (PST)
Thanks Chris, Paul & Jeff for your comments!And yes, Alan, this is the kind of 
discussion that makes this forum valuable.

I agree with all three commentators and we will change the captions to these 
pictures. I also agree with you, Chris, that Sooty and Short-tailed are by far 
more similar to each other than both are to a Wedgy. I would be very 
embarrassed if we had captioned this bird "Wedge-tailed Shearwater"! However, I 
don't necessarily agree that the comparison to an "outgroup member", such as a 
Wedgy or - at the other end - to a Flutterer, is totally irrelevant. I think 
that the flight style (depending on the weather/wind condition) is important, 
too, although it apparently doesn't always work: I am still surprised how 
outstanding this bird's flight style was and how different it looked from all 
the other present Short-tailed Shearwaters.
As I said, I do agree that the field marks you guys mentioned are "harder" than 
mineand the ID should be Short-tailed Shearwater.

Here are Raja's pictures of a Sooty Shearwater (I hope ;-)
Actually, I think that this particular bird is one of your example birds "Sooty 
at rest", Paul. Especially picture 2 in Raja's series shows that even a Sooty 
can show a steep forehead. This underlines that we always need to look at a 
combination of field marks.

BTW, I also had my first encounters with Short-tailed Shearwaters in direct 
comparison to Sooty Shearwaters in California, when I used to be a pelagic 
leader on Debi Shearwater's trips there. Because of my failure to ID them she 
kicked me out and I had to flee to Australia - just kidding...

Thanks again for the comments (I am actually surprised that no one commented on 
some of the jaegers...)



Nikolas Haass

Sydney, NSW

From: Chris Corben <>
To: "" <> 
Sent: Monday, January 30, 2012 3:11 PM
Subject: Black-winged Petrel, White Tern, False Killer and more: SOSSA pelagic 
off Wollongong NSW
Hi all

I think Short-tailed vs Sooty is a very interesting problem in many ways. In 
the hand they are always easy to tell, even ignoring measurements, just by the 
colour of the underwing. However, seeing that in a reliable way in the field is 
extremely difficult and hugely lighting dependent, so it's very easy to be 
mislead, even if you know exactly what to look for.

This is where digital cameras have made a huge difference. Even though a photo 
lacks a whole lot of important cues, it still represents a very unbiased view 
of something. The photons really did this, without any filtering by millions of 
neurons in the brain which are there for the very purpose of letting us see 
things which aren't there! This filtering is why we are so clever about what we 
see, but it still means that we largely see our lives through a succession of 
optical illusions!

Irrespective of all the ways in which Sooty and Short-tailed can appear to 
differ, they are still FAR more like each other than either is like anything 
else! While I can appreciate Nikolas' point about confusing the bird with a 
Wedgy, the fact is that ANY Sooty is always going to look far more like a 
Short-tailed than a Wedgy, once you see it well. I am sure you could briefly 
think a Fluttering looked like a Wedgy, but doing so would not be support for 
it being a Huttons, even though you could argue that a Huttons looks MORE like 
a Wedgy than a Fluttering looks like a Wedgy. The difference between a Sooty 
and a Short-tailed is so small compared to the difference between either and a 
Wedgy, that temporarily thinking it looked like a Wedgy just isn't really 

I have had excellent opportunities to watch both Sooty and Short-tailed 
together on many occasions, and perhaps the best of these have been in 
California, where the argument has been expressed that you cannot tell them 
apart (but few would accept that). I have had plenty of examples where the 
difference between a Sooty and a Short-tailed was so obvious, that I started to 
wonder why I ever thought they were confusing. And then, just when feeling 
extra good about it, another bird would come along which made everything look 
confusing again, despite having excellent views. None of this is surprising, 
because it's just an inevitable consequence of the bell curve, which is so 
basic to all of biology.

The bird off Wollongong strikes me as more like a Short-tailed and Nikolas as 
more like a Sooty, and the photos are good. The fact that we cannot instantly 
agree on its identity when faced with photos this good is just an unambiguous 
testament to the genuine difficulty of this problem!

Cheers, Chris.


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