Where possible PFTCS will briefly review articles in the popular and scientific birding literature relating to seabirds and other marine wildlife.Here are four highly rewarding articles dealing with field identification and the rediscovery of very poorly known tubenoses. Seabird enthusiasts will enjoy reading each of them.
Greg Gillson (2008) Field Separation of Sooty and Short-tailed Shearwaters off the West Coast of North America. BIRDING March/April 2008 40(2):34-40. Click here for article as PDF.
Identification of Sooty and Short-tailed Shearwaters at sea or from land-based seawatches can be challenging and is covered that well by most field guides. This article visits the problem from the perspective of birders on the west coast of North America where Sooty Shearwaters are abundant and Short-tailed Shearwaters - apparently mostly juveniles - are present in smaller numbers. The article discusses salient field marks including a detailed discussion of differences in structure, flight style and behavior. My one niggle about the article is the layout and number of photos. Key comparison of the two species, either in flight or on the water, are not presented side-by-side and an ID article of this type really needs more photographs to properly convey the differences. I would like to have seen a close-up of the heads to illustrate the differences in bill length/depth and forehead shape. The painting comparing the two shearwaters in parallel flight is a little too stylized for my taste and over-emphasizes the differences. I appreciate that these things are usually beyond the authors control. Otherwise, this is a useful article that identifies a glaring gap in the popular birding literature. Gillson is one of the best known names in Oregon birding and has been running pelagic trips from Newport, Oregon, for a number of years.
Chris Harbard (2008) Beck from the Dead. BIRDWATCH April 2008 issue 190:28-29.
A concise and accessible account of the recent rediscovery of Beck's Petrel (Pseudobulweria becki) in the waters off New Ireland, Papua New Guinea. The tale begins with Rollo Beck - an ornithological collector of extraordinary talent - who took the first specimens in the late 1920's and picks up again in 2003 with Hadoram Shirihai who glimpsed three candidates during research visit to the Bismark Archipelago for his upcoming seabird books. Another tantalizing candidate was studied by birders on the 2007 WPO. Finally the dream came true in July/Aug 2007 when Hadoram mounted a one-man expedition to the area, successfully chumming in small flocks of fresh juveniles and a lesser number of adults. Armed with this new information, the 2008 WPO got excellent views of this pelagic jewel. The piece includes two spectacular flight shots of the gorgeous petrel (there's a larger version of the dorsal shot on the contents page) and an amusing action shot of Admiral Shirihai firing a fusillade of pixels aboard his skiff with a crew of local boatmen serving as helmsman and chummer respectively. Harbard is a regular columnist for Birdwatch and was assisted in this piece by well-traveled seabird fan Tony Pym.
Hadoram Shirihai (2008) Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. B.O.C. 2008 128(1):3-16.
A scientific and highly readable paper that breaks into two parts. The first summarizes the background to the rediscovery with discussion of previous sightings, speculation on likely breeding sites, field identification and future conservation challengs. The second part describes other notable seabirds observed by the author during visits to the region. Foremost are multiple birds observed in 2003 and 2007 at various spots in and around New Britain PNG and New Ireland PNG, that resemble descriptions of Fiji Petrels (Pseudobulweria macgillivrayi). So little is know about this taxa that it is possible these are something else. The type specimen was taken in 1855 on the island of Gau in Fiji's Lomaiviti Archipelago (decimal degrees -18.066667°, 179.333167°). It was not recorded again until 1895 when an adult and fledgling were found by Dick Watling, again on Gau. Using spotlights, there have been a few more sightings from the island. It is worth stressing that the sightings described by Shirihi in this article as well as a similar bird spotted by Howell and companions on the 2007 WPO are almost exactly 2,000 miles from Gau and so it's probably good to keep an open mind about the species involved at this point. Hadoram plans a repeat visit to document these birds and I can imagine the well advertized rediscovery of Beck's Petrel will draw other seabird enthusiasts to the area, not least the annual swing through by the WPO en route to Japan. Definitely the cutting edge of seabirds discovery!
Steve N. G. Howell and J. Brian Patteson (2008) Variation in Cory's and Scopoli's Shearwaters. ALULA 1-2008 Vol 14: 12-21.
This richly illustrated article discusses field identification of Cory's Shearwater (Diomedea [d.] borealis) and Scopoli's Shearwater (Diomedea [d.] diomedea) with emphasis on birds studied off North Carolina, USA supplemented by photographs from the breeding grounds in the northeastern Atlantic or Mediterranean. The authors are quite candid about the difficulties involved, due to the subtle nature of the characters (principally differences in bill proportions, extent of white tongues on undersides of the primary feathers and relative color of the head) and our limited knowledge about the extent of variation. With respect to bill size for example, the differences between males and females needs to be appreciated. The bill of a female Cory's for example is very similar to that of a male Scopoli's. Lighting and angle are also very significant. Photos are presented showing the same two birds (one of each) but the differences are more obvious in one shot compared to the other. They also discuss a number of birds that seem indeterminant as well as some fairly clear cut examples. Even with these uncertainties, Scopoli's may be more common outside of the Mediterranean (e.g. in North American or Northern European waters) than is generally appreciated but for many individuals, it may not be possible to firmly ascribe them to (sub)species without a comprehensive set of photographs. There are probably quite a few 'Cory's' specimens held by local museums that will not have been critically evaluated and these may give a better sense of relative abundance. Some of the lessons provided by this study (including the numerical scoring system) can be applied to discussion of other shearwaters and case in point, the authors include a photo of two skins of Macaronesian (Baroli's) Shearwaters to illustrate the variability in a feature that has been described as diagnostic. Obviously that is whole different story but underscores the need for considerable caution in over-interpreting these types of plumage differences. Brian Patteson is synonymous with pelagic birding out of Virginia and the Outer Banks of North Carolina and sees large numbers of Cory's-type shearwaters at close hand during the summer months. Steve Howell is a recognized authority on seabird identification and although based in California, has been working with Patteson as a guide for several spring seasons.
**********
No comments:
Post a Comment