Separation of boydi race of Little Shearwater from Audubon's Shearwater


I generally try not to get too deeply into reviewing single images of birds on the Internet -- the pitfalls seem too great, especially with cryptic genera such as the smallest _Puffinus_ shearwaters. The shearwater posted by Paul Guris and Angus Wilson (and evaluated by many) appears to me to be a "black-and-white" shearwater rather than a Greater, for all the reasons mentioned by Bruce Mactavish and Julian Hough. I can't add much to their comments.

I do wonder, pushing the envelope a bit, whether we can easily settle on Audubon's Shearwater from this single image. I do agree that Manx is ruled out, but what about the _boydi_ subspecies of Little Shearwater, sometimes considered a form of Audubon's? I assume that it has some structural features and flight patterns that would make it more similar to _baroli_ in the field, but it lacks the white face of that form, I believe (though I'm not certain that all _baroli_ have white faces). I have not myself been able to find literature on _boydi_ that suggests how to identify it in the field. European voices on this subject would be most welcome.

I don't normally lose sleep over these things, but in September this year, a small black-and-white shearwater with bright powder-blue legs washed up at Cape May. I got a call from one of the finders and ransacked my library to see whether leg color might be significant in the identification of the bird. Meanwhile, hurricanes had pushed a few small shearwaters, presumed Audubon's, into the Chesapeake Bay. Some of the notes below were sent to the Cape May folks; the specimen, as I understand it, has been sent to Philadelphia but not yet processed.

Ned Brinkley, Cape Charles, VA (Phoebetria@AOL.COM)
Message to ID-Frontiers: Mon, 20 Dec 1999 14:38:08


Little Shearwater(s) and little shearwaters

I've always been under the impression that blue legs were diagnostic for Little Shearwater, and I could not find any material in my library to suggest otherwise. Assumedly because they're not useful in most field situations, though, the legs are not emphasized.

I was not able to find any firm answers to the question of field identification of various forms of Little Shearwater. I have only seen one Little, an _elegans_, poorly, off Argentina, where a few Manx were around for comparison. I've never seen anything that looked like _baroli_ off NC, and as for the darker-faced birds, Iím not sure that I understand how field ID is possible altogether. With a bird in flight (so that wing pattern and structure and flight style could be observed), perhaps it is possible.

Previous North American records are few. One hit the lighthouse at Sable Island, off Nova Scotia, 1 September 1896 (AMNH 407683), and the specimen is still in NYC for viewing. I havenít yet looked at it. In THE BIRDS OF NOVA SCOTIA (Tufts, R. W. 1961. Halifax: NS Museum), it is identified as subspecies _baroli_. I asked Ian Maclaren about the date on this record -- whether it might be a week or so off (as there was a hurricane that otherwise might have accounted for its presence there). He said no, that the lighthouse keeper, R. J. Boutilier, was an excellent records keeper and wouldn't have gotten this wrong.

The other bird was a hurricane waif found alive on Sullivanís Island, South Carolina, in late August 1883. It wasnít correctly identified until 1924 (Peters, J. L. 1924. A second North American record of _Puffinus assimilis_. Auk 41: 337-338.). I canít find material from BIRDS OF SOUTH CAROLINA. Maybe there is more in that book on the blue legs.

There are other claims of Littles after the 19th century. Most are condensed in David Lee's 1988 article 'The Little Shearwater in the western North Atlantic', in AMERICAN BIRDS 42 (2): 213-220. Some of the mid-Ocean records are probably correct, and I think some of the records off Canada (Georges Bank, etc.) are also potentially correct. I haven't yet seen details to suggest that mid-Atlantic records are firm.

Lee (1988) confirms the Nova Scotia bird as _baroli_, which may lack the starkly white face with dark eye surrounded by white, I think (I base this on Lee's review of specimens of this race, which seemed similar to Audubon's around the eye, rather than on Killian Mullarney's sketches from Tenerife, Canary Islands, which show white-faced birds with obvious eyes in a field of white). This is the subspecies that has strayed north to England and that breeds off Madeira, the Salvages, Canaries and probably the Azores. Perhaps the facial patterns differ among various populations on these islands.

Lee comments: 'I doubt that the blue leg color of Little Shearwaters would be apparent under most sea conditions, or any more useful in the identification of flying birds than the blue legs of Long-tailed Jaeger. Furthermore, the shearwaters' low flight, with infrequent tilting glides, would seldom provide a chance to see leg color.' Also: The slightly smaller bill of the Little Shearwater seemed apparent on a resting bird I saw, but after examining skins, I have trouble believing that this character would be useful.

How about useful characters? Anthony McGeehan's article ('A Little help' in BIRDWATCH September 1995: 38-42) is outstanding but focuses mostly on jizz and flight pattern. He does describe a pale midwing panel (paler than blackish upperparts) that appears to be the secondaries and most of their coverts -- just a bit more silvery than the primaries and the scaps/mantle/lesser coverts. It comes out looking like a wedge of paler feathers, widest where it abuts the primaries (See photo page 193 in Harrison's photographic guide). I havenít seen this in Audubon's or Manx, for what itís worth. I don't know of other firm plumage characters that might separate Little -- other characters seem to be variable or slight or require a bird in hand.

I think Little would look proportionately shorter-tailed than Audubon's. Undertail covert coloration is definitely variable (white to all dark brown) in Audubon's and may be so in Little. Undertail coverts are white in Manx, apparently not variable.

Soft parts in Manx (from BNA account by Lee and C. Haney): ìTarsus purple-flesh or pale flesh; inner toe and base of middle toe pale flesh, brighter in juvenile. Top of webs either purple-flesh with black sides to the outer toe and half of upper side of central toe, or pale pink with black markings. Remainder of toes and claws black. Pink pigments fade considerably in adults at end of breeding season.

I don't think any of that can be construed to be powder blue.

I have looked in Bannermanís BIRDS OF THE CAPE VERDE ISLANDS (on 'Alexanderís Little Shearwater', pp. 165-169 -- the local form there is subspecies _boydi_, which he feels is a race of Audubon's) and found nothing useful there on soft part colors.

I have seen leg/feet on dead, dying, shot and live Audubonís (not that hard to see in the field; cf. FIELD NOTES 51 [5]: 1064, an in-hand photo of an Audubon's with pink legs and feet), and all were either pink or a little darker distally and flesh or pink basally. I canít find any source that suggests Audubonís can ever have powder-blue legs or feet (though apparently juvenile birds in the Indian Ocean can have violaceous tones in their feet?), but several sources imply that blue legs are diagnostic, in the Atlantic group of black-and-white shearwaters, of Little.

Ned Brinkley, Cape Charles, VA (Phoebetria@AOL.COM)
Message to ID-Frontiers: Mon, 20 Dec 1999 14:38:08


I agree with Ned Brinkley that it we should all probably look more carefully at leg color on the smaller shearwaters. The _boydi_ race of Little Sheawater (breeds in the Cape Verde Islands off West Africa) seems a genuine possibility in eastern North America and the Caribbean. How this would be identified in the field is very poorly addressed in the literature. In fact, I am not sure why this taxa is classified as a member of the Little Shearwater cluster (Puffinus assimilis) rather than the Audubon's cluster (P. lherminieri). There are even arguments that _boydi_ should be given species status in its own right (Boyd's Shearwater). Besides foot coloration, I recall that the voice may be an important difference?

A good time to look at leg color is during take-off. In daylight hours, shearwaters are often encountered resting on the water, typically in small rafts. Most take flight as the boat approaches, providing an excellent opportunity to view (and perhaps photograph) the leg and foot color. Calm conditions are probably best as the birds have to run a short distance to become airbourne, often holding their legs out (in case they are needed for an extra push?) for the first few wing beats. Sometimes they shrug to rearrange their feathers and may paddle their legs in the air as they do so.

For an example of how the leg/foot color can be visible in the field, take a look at the photo of an Audubon's Shearwater taking flight posted on my web site.

http://www.oceanwanderers.com/AudoShear.html

The pink legs and feet a very evident. Note also the dark markings along the rear side of tarsus and the outer digit.

I would love to hear from anyone with photographs of _boydi_ (Cape Verde Islands) or field experience of both _boydi_ and _P. l. lherminieri_.

Angus Wilson, New York City (wilsoa02@med.nyu.edu)
Message to ID-Frontiers: Mon, 20 Dec 1999 15:45:23


I have some small b&w shearwater stories to tell myself, but have nothing substantial to add to any discussion on field identification. I do suspect P.a. boydi might occur in the western Atlantic, and could be easily overlooked. I have put my stories and a couple of pictures on this web page.

http://members.bellatlantic.net/~dbarber/shearwater.html

Bob Barber (bob@VERTIGO.HSRL.RUTGERS.EDU)
Message to ID-Frontiers: Mon, 20 Dec 1999 21:34:39


I also hesitate to contribute here for fear of being misled by subjective impressions and poor memory. I am familiar with Manx, have seen 10's of baroli (Madeira, the Canaries and 1 in Senegal), about 20 boydi from shore based observations in Senegal and once I have seen flocks of Audubon's off NC, some years ago. My subjective impression of Audubon's, relative to Manx, was that it was long-bodied/long-tailed and looked almost aukish in flight, whereas baroli and boydi are not so long-bodied/long-tailed, have a weak flight (sometimes recalling Common/Spotted Sandpiper) and, relative to Manx, slightly broader wings. If my memory is not failing me (somebody put me right if it is), I also recall that Audubon's is distinctly brown, as Manx can appear in bright sunlight, but I have never seen a brown cast to either baroli or boydi. This year in late September, we had our first baroli off Senegal, viewed from the shore, at a time when there were also good numbers of Bulwer's Petrels and Wilson's Storm-petrels also visible from the shore.

The beady eye surrounded by white, lack of black under-tail coverts and silvery panel on the upperside of the wing were all obvious. The silvery wing panel is often easy to see on baroli, especially flying away, but I have not seen it on the wings of boydi, and I assume Audubon's never exhibits this. The dark under tail coverts and dark cap extending below the eye on boydi are not too hard to see using a x27 scope from shore at (say) 400 metres - although this distance is too far to see if it has an eye-ring like (some?) Audubon's or not. As for leg colour, I have never managed to see it in the field, but have in the hand on the Salvages.

Getting back to the original photo that started all this on http://www.oceanwanderers.com/Shearwaterdisc.html - it looks long-bodied/long-tailed to my eye, and I believe I can see an eye-ring on the enlargement? - but photos can deceive.

Dick Newell, UK (Dick.Newell@SMALLWORLD.CO.UK)
Message to ID-Frontiers: Tue, 21 Dec 1999 17:11:03


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