Short-tailed and Sooty Shearwater (1 Viewer)

I've posted a discussion of the ID of these two species at my website here
http://www.sibleyguides.com/2011/07/can-short-tailed-shearwater-be-identified-in-the-field/
concluding that bill size and head shape together is the only reliable distinguishing feature, and that just barely works.
So I have a few taxonomy-related questions for this list. I don't have access to the Handbook of Australia/New Zealand/Antarctic birds, and I'm finding very little info in the references I do have. Apparently small numbers of Sooties nest in New South Wales and Tasmania where Short-tailed is common. Are they in mixed colonies? Are there any known or suspected records of interbreeding? Is there some big difference in voice or DNA? They have different breeding ranges and migration patterns, and they do sort out into two discrete groups on bill size, but visually I don't think they are any more distinctive than Cory's and Scopoli's.

Martin Garner has also recently highlighted this ID scenario:

• Short-tailed Shearwater: Short-taileds and Sooties Compared.
• What is this Seabird? Another potential target bird for Varanger?

David,

You are correct about the two species breeding in the same locations. To take one example, I believe Tasman Island off the SE corner of Tasmania has 6000 pairs of Short tailed and 1000 pairs of Sooties. To give an idea of relative abundance off SE Australia, the atlas of seabirds for that area says that it had 671 records of Sooties in its database ... and over 1.2 million of Short tailed.

I am not aware of records of interbreeding. I will ask around.

HANZAB doesn't say much on their taxonomy. In the call section it says for Sooty Shearwater "calls deeper, slower and less hysterical than Short tailed Shearwater". I note that the paper on seabird taxonomy by Penhallurick and Wink suggests Short tailed and Sooty diverged from each other before Sooty diverged from Great, Flesh-footed and Pink footed.

There's also a good table on page 199 of Albatrosses, Petrels and Shearwaters of the World by Onley and Scofield summarising differences between the two species.

I'll send a link to your blog post to a few Australian seabirders and see if they have any input to add.

David,
Have you seen Raymond et al 2010 and Shaffer et al 2011 (attached)?
MJB

I have had a look at one other paper on shearwater taxonomy: J. Austin,
Molecular phylogenetics of Puffinus shearwaters: preliminary evidence from mitochondrial cytochrome b gene sequences Molecular Phylogenetics and Evolution, 1996; 6(1):77-88. It tells the same story as Penhallurick and Wink - while Sooty and Short tailed are closely related, they diverged from each other somewhat earlier than some other closely related species.

Note that as Penhallurick and Wink was based on samples deposited in Genbank, it may be that both these papers are based on the same raw data.

David if you PM me your email address I can send you the paper.