Tuesday, 19 August 2014

Black-capped Petrel photos from Hatteras

So, this one is a bit different to my recent travelogue posts. So, I'll set the scene - last Saturday, 9th August, I was fortunate to go out from Cape Hatteras, North Carolina with Brian Patteson on 'The Stormy Petrel' in pursuit of pelagic birds. As someone who has done a fair number of different pelagics, this was a professional one with an excellent boat and good use of chum...

However, for me, there was one real purpose of going - to see Black-capped Petrel and study their variability. And for sure, it's a very variable species where I reckon some people may have one extreme - the 'white-faced' individuals - within their search image. I also learnt that Bob Flood and Ashleigh Fisher 'pterodroma petrels' book is bloody excellent too; I knew this as I reviewed it for Birdwatch last year but flicking through ad hoc and then using it with a purpose are two different beasts. What it notes, and I noticed too, are the following macro points on the 40 or so birds that I saw: -
- there is a great array of variability in Black-capped Petrels. I only saw one bird that would fit the 'white-faced' criteria, with all others being 'dark-faced' or intermediate birds.
- underwing is extremely variable, and seems to some extent to be much paler on intermediate and 'white-faced' birds. Though this is just through the one trip I went on.
- they're not like Great Shearwaters at all; though I did go back to the book on one particular 'dark-faced' bird that looked in some respects close to a Bermuda Petrel - though a check of the large bill and the extensive white on the rump/uppertail confirmed it as a Black-capped.
- wing moult varied somewhat; perhaps this being age related. The 'dark-faced' and intermediate birds seen were largely showing some state of wear (inevitable for a non-breeder).
- the birds skirted the boat, sometimes following in the wake loosely. On one occasion, a bird was sat on the sea in amongst Cory's Shearwaters.

All the above is very interesting, with a lot of the Black-capped Petrels seen at a sea depth of c.2,000 feet. Given that all the other species seen, with the exception of Bridled Tern, are regularly seen off the Azores I can but hope to bump into a Black-capped Petrel out there one day. But until I do, here are a fair few photos of this quality species. Recent studies suggest the two types are genetically distinct (probably at subspecies level).
Photo 1. A typical 'black-faced' individual in active wing moult.

Photo 2. Same bird as photo 1 showing what I'd call an average underwing pattern.

Photo 3. A 'dark-faced' individual with a particularly dark underwing.

Photo 4. Probably what you'd call an intermediate morph, though on the darker side. Note the relatively pale underwing and also the dusky half collar on the hindneck.

Photo 5. A 'dark-faced' bird exhibiting wing moult as well as the broad white rump and uppertail.

Photo 6. Same bird as in photo 5; showing the dark cap with a dusky hindneck extending into the mantle.

Photo 7. An intermediate bird, that initially I thought could be a 'white-faced' bird. However, note the dark smudging behind the eye and also slight hindneck markings.

Photo 8. Another photo of an intermediate morph - note the pallid underwing appearance to the true 'dark-faced' individuals.

Photo 9. Another example of an intermediate morph, on the paler side than average but still showing black to the eye, dusky hindneck and heavy wing moult.

Photo 10. Intermediate morph again showing classic underwing pattern and capped appearance.

Photo 11. Perhaps what most people have as a 'classic' Black-capped Petrel - the isolated black cap, obvious white rump and white hindneck.

Photo 12. Same bird as photo 11 - note the slight supercilium on this intermediate bird.

Photo 13. Illustration of a classic pale underwing - little wing moult going on here. Breeding on Hispaniola spans November to May, so perhaps this could be a young bird?

Photo 14. 'Dark-faced' birds especially seemed to be in relatively heavy wing moult.

Photo 15. Another intermediate bird, showing a couple of markings on the hindneck; could well be the same bird as in photo 13 and shows relatively fresh wings.

Photo 16. The facial appearance of this species varies dramatically - some 'dark-faced' birds like this can look rather 'mean' in comparison to their more docile looking intermediate/'white-faced' relatives.

Photo 17. The only truly 'white-faced' bird of the trip. Note almost  a lack of a black cap, the lack of any markings on the hind neck. Also, the theory is that at this time of year adult 'white-faced' birds should be much fresher winged - as in May/June they're often in heavy moult.

Photo 18. Same bird as above, showing the obvious white nape with no dark markings.

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