The occurrence of Herald (Trinidade) Petrel Pterodroma [a.] arminjoniana in the northern hemisphere Edward S. Brinkley The species was not known to be a regular summer visitor in small numbers in the North Atlantic, specifically in the Gulf Stream and Gulf Stream-‐influenced waters off the mid-‐ Atlantic United States, until the present decade, beginning with documented records from 1991. The form (P. [a.] arminjoniana) seen off North Carolina differs significantly in plumage from its Pacific counterpart, the Herald Petrel (P. [a.] heraldica), and no illustrations of the former are widely available. Storrs Olson of the Smithsonian Institution and David Lee of the North Carolina Museum of Natural Sciences have an (as yet) unpublished paper "splitting" the two forms (on evidence in addition to differences in plumage), but I do not have access to this paper at present. Gary Nunn of the American Museum of Natural History has, as I understand it, collected tissue samples of all gadfly petrel taxa for comparison and may publish results in the near future. W. R. P. Bourne, in Palmer (1962. Handbook of North American Birds. Vol. 1. New Haven: Yale UP), suggests that even the recognition of heraldica as a subspecies is "doubtful," but that book has become outdated for many aspects of seabird taxonomy and identification. The Pacific taxon is certainly distinct in terms of plumage, morphology, and possibly call-‐types (see Appendix II) from the Atlantic taxon, and most researchers outside the United States already consider P. heraldica to be a species separate from P. arminjoniana. Given that a strong paper was recently published proposing specific status for what are now considered dark and light morphs of P. heraldica (Brooke, M. deL. and G. Rowe. 1996. Behavioural and molecular evidence for the specific status of light and dark morphs of the Herald Petrel Pterodroma heraldica." Ibis 138.3: 420-‐438), birders should attend as closely as possible to birds at sea -‐-‐ not just their plumage but also their structure, including the shape of bill -‐-‐ and obtain as much visual documentation as possible. Dark and light morphs of the taxon nesting in the South Atlantic were considered separate species for all of the previous century since their discovery in the late 1860s and for most of the current century. Currently, birds nesting in the Indian Ocean at Round Island, Mauritius are considered to be of the nominate form, and the birds on Easter Island (which have also been classed as forms of P. neglecta) are held to be the Pacific form heraldica, sometimes referred to as paschae. The most similar species in the genus (Murphy's Petrel, P. ultima, Providence/Solander's Petrel, P. solandri, and Kermadec Petrel, P. neglecta), but I have been able to study a good series of P. ultima at the Smithsonian Institution, on a 20 June 1996 excursion there, along with P. a. arminjoniana and P. a. heraldica, from Atlantic, Indian, and Pacific Oceans (see Appendix I, below). The only other gadfly petrels with which I am familiar in the field (P. mollis, P. cahow, P. feae, P. incerta, P. brevirostris, and P. hasitata) are not likely to be
confused with any morph or taxon of Herald/Trinidade Petrel, even in the cases of dark morphs of P. mollis or P. hasitata, both of which are very rare, the latter probably extinct (and probably not a morph, as once thought, but a species in its own right: see Imber, M. J. 1991. "The Jamaican Petrel -‐-‐ Dead or Alive?" Gosse Bird Club Broadsheet 57: 4-‐9). A worn P. incerta might look like some of the paler intermediate morphs of Trinidade Petrel, but that species has a rather darker underwing than such morphs. P. ultima looks generally chunkier (especially more "bull-‐headed") and shorter-‐billed in the museum tray, at least, and all the Smithsonian specimens are decidedly grayer above and below than all the Trinidade Petrels. But a Murphy's with no white at the base of the bill and generally dark plumage might look frightfully like a Trinidade otherwise. There is a fairly good consideration of identification pitfalls for dark morph Trinidade Petrels in Gochfeld et al. (1988, below), although some species -‐-‐ such as the large P. macroptera -‐-‐ should be less likely as stumbling blocks than those authors suggest, if one assumes an experienced seabirder. The birds that Peter Harrison paints in his editions of Seabirds (1983/85. Boston. Houghton Mifflin) seem more likely to be members of the Pacific Ocean taxon, because they do not resemble the birds we see off Cape Hatteras or the specimens at the Smithsonian (collected in 1975-‐1976 at Trinidade by Storrs Olson), but they do resemble the Pacific Heralds in the Smithsonian collection. The same holds for the two photographs presented in Harrison's photographic guide, A Field Guide to the Seabirds of the World (1987. Lexington, Massachusetts. Stephen Greene). I hope the present text will stimulate discussion with Pacific Ocean, Indian Ocean, and South Atlantic researchers/birders in further working out the field identification of these gadfly petrels. It will be difficult to find points of comparison common to all of us, but where possible, I would suggest respondents refer to seabirds with more cosmopolitan distribution. The Atlantic Ocean taxon: specimen record The Atlantic taxon has a much more restricted nesting range than its Pacific counterpart, being limited to the Ilha da Trindade, 700 miles east of Espirito Santo in Brazil (or just Trindade, formerly called [South] Trinidad in English, now generally written Trinidade -‐-‐ with an "e" to distinguish it from the Caribbean island -‐-‐ but also written as Trindade, closer to the Portuguese, in some texts in English) in the South Atlantic and the Martin Vas [Vaz, in some texts] islands, a small group not far from Trinidade. Many collectors and explorers have stopped here to collect this species, among others. Those that I have seen mentioned include: one by Brazilian ornithologists (specimens in the Natural History Museum at Rio); one by the Smithsonian in December 1974/January 1975 (20+ specimens); one by the Cleveland Museum of Natural History 24 December 1924 through 5 January 1925 aboard the "Blossom"; a one-‐day venture by R. C. Murphy while aboard the "Daisy," a whaling ship, on 8 April 1913 (9 specimens); one by the Italian corvette "Magenta" (description of light and dark birds by Giglioli) in early 1868; one in November 1874 by the Earl of Crawford aboard the "Venus" (then Lord Lindsay; specimens presumably obtained but lost, "thrown overboard as lumbering the decks in heavy weather on the night after the visit" to Trinidade; see Saunders, H. 1880. "On the Sea-‐birds collected during the Voyage of Lord Lindsay's Yacht 'Venus' from Plymouth to Mauritius in
1874." Proceedings of the Scientific Meetings of the Zoological Society of London 161-‐165); one by the naturalists of the "Discovery" expedition to Antarctica on 13 September 1901, with E. Wilson (one dark morph, three apparent dark intermediate morphs, two males and a female; three apparent light or light intermediate morphs, two males and a female; as well as downy young and eggs); and one on 3-‐4 January 1905 by Michael John Nicoll, aboard the "Valhalla." Apparent prospecting by the species has been noted in the Caribbean off Puerto Rico (Gochfeld et al. 1988, below), but that individual was not collected. History of description There is a long and complex history of the discovery and naming of the various taxa associated with the names "Herald Petrel," "Arminjon's Petrel," and "Trinidade Petrel," (Hess 1997). The form Pterodroma [a.] arminjoniana, was first described by Giglioli and Salvadori in 1869 (1869. Ibis 5: 65) as Aestrelata arminjoniana, with the various morphs classified in various ways later by Salvin, Nicoll, Sharpe, and Godman. It includes birds formerly named Aestrelata sandaliata, arminjoniana, armingoniana [a typographical error], wilsoni, trinitatis, and chionophara. Apparently the Indian Ocean form was described at Round Island, its only known nesting area there, quite late in the game: 27 November 1949 (Murphy, R. C. and Pennoyer, J. M. 1952. "Larger Petrels of the genus Pterodroma." Am. Mus. Novit. 1580: 1-‐21). The taxon is described as "dichromatic" by Murphy (light and dark morphs; 1936. Oceanic Birds of South America. New York: American Museum of Natural History.), although he acknowledges there the designation of "intermediate" morph by P. R. Lowe and N. B. Kinnear (1930. "British Antarctic ['Terra Nova'] Expedition 1910." Zoology 4.5:103-‐193, pls. 1-‐16) based on different pigmentation of legs and feet, and in a later article on gadfly petrels with Jessie Pennoyer (1952) resolves that the species is "polychromatic." Murphy (1915. "The bird life of Trinidad Islet." Auk 32: 332-‐348, pls. 23-‐25) had in fact already distinguished three recognizable forms, including one apparently symmetrically leucistic bird (described below) which he dubbed "Aestrelata chionophara." Drawing on previous descriptions, he referred to the least common form, surprisingly the all-‐dark morph, as "Aestrelata trinitatis," the paler morphs as "Aestrelata arminjoniana" (with darker "wilsoni" and lighter "wilsoni" phases, adapting earlier designations for lighter and darker intermediates), and to the palest form, the leucistic bird, as "Aestrelata chionophara," the Snowy-‐mantled Petrel, "more beautiful than all its congeners, clad in a black-‐flecked cloak like ermine." This is understatement, to judge from photographs and illustrations. A stunning plate by Louis Agassiz Fuertes graces the article on that bird: Murphy, R. C. 1914. "Preliminary Description of a new petrel." Auk 31: 12-‐13, one plate. Don't miss this one. (Those interested in the changing history of taxonomy will want to look at Wilson, E. 1904. "The Birds of the Island of South Trinidad." Ibis 208-‐213; Sharpe, R. B. 1904. "Report on the Birds obtained by the National Antarctic Expedition at the Island of South Trinidad." Ibis 214-‐217; and Mathews, G. M. 1936. "Dove-‐like petrels of the genus Pterodroma." Ibis 6: 376-‐377.)
In Palmer's 1962 Handbook of North American Birds (Vol. 1), two extremes and "all degree of intermediates" are rightly recognized. There is a good deal of gradation among forms, especially between light and intermediate (as for related taxa: see Bailey, S. F., P. Pyle, and L. B. Spear. 1989. "Dark Pterodroma Petrels in the North Pacific: identification, status, and North American occurrence." American Birds 43.3: 400-‐415.), but I will maintain three "morphs" for the sake of convenience here, referring to some intermediates as "light intermediate" and some as "dark intermediate." The party of the "Blossom" expedition collected a large number of these petrels. Most of these skins have ended up at the Peabody Museum at Yale University, in New Haven, Connecticut, but a good number are still at the Cleveland Museum, and others are scattered across the midwest, mostly at research universities. Anyone with access to these birds is invited to post findings in response to this posting. A WORD OF CAUTION Seabirds observed at sea, from a small vessel, should be subject to more tenuous (less thundering) conclusions, in my opinion, than should landbirds, because the plumages of many seabirds, especially tubenoses, seem radically changeable under different lighting conditions and with wear. Moreover, observers are often in very different mental states on small boats -‐-‐ some hale, some ill, some delusional and groggy because of Scopalamine and other drugs -‐-‐ and they contend with the boat's motion very differently. (Thus, the condition of plumage and the precise sort of lighting and the bird/observer/light source orientation should be recorded carefully as it alters in the field.) With the 31 July 1993 North Carolina record of Bermuda Petrel, a bird in fresh plumage, for example, the black of the upperparts looked to me "like anthracite" in the field, whereas the worn 26 May 1996 bird appeared a "dusty brown" above. The lighting conditions were different (overcast versus hazy sun), and two individuals of the same species showed different conditions of plumage -‐-‐ the impression in the field was of remarkably different birds. (For a stunning example of these variables, compare the photographs of Murphy's Petrels on page 1102 of Kevin Zimmer's excellent "Murphy's Petrels on Ducie Atoll." American Birds 46.5 [Winter 1992]: 1100-‐1105.) This is also apparent in Black-‐capped Petrels, of which we have seen many thousands over the past two decades. THE PHOTOGRAPHIC RECORD As far as I know, there are only fifteen published photographs of eleven live adult (Atlantic) Trinidade Petrels: 1) Michael John NICOLL. Three Voyages of a Naturalist, Being an Account of Many Little-‐Known Islands in Three Oceans Visited by Valhalla. London: Witherby. 1908. Page 43. Two adults and two chicks at nest. DARK AND LIGHT MORPHS 2) Robert Cushman MURPHY (1915. "The Birds of Trinidad Islet."
Auk 32: 332-‐348. Plate 24, bird in flight.) LIGHT MORPH 3) Arthur A. ALLEN (1934. "A New Bird for North America." Bulletin to the Schools, the University of the State of New York 20.13: 134-‐135, photograph of live bird. DARK MORPH 4) UNATTRIBUTED [one or more of the authors], three photographs in 1988. "Herald Petrel new to the West Indies." Michael GOCHFELD, Joanna BURGER, Jorge SALIVA, Deborah GOCHFELD. American Birds 43.3 (Winter 1988): 1254-‐1258. DARK MORPH 5) Killian MULLARNEY, American Birds 45.3: 511 (Fall 1991) INT. MORPH 6) Michael TOVE, American Birds 46.2: 251 (Summer 1992) DARK MORPH 7) Alan BRADY, American Birds 48.1: 99 (Spring 1994) DARK MORPH 8) Brian PATTESON, Winging It 6.1: 5 (January 1994) LIGHT MORPH 9) Brian PATTESON, Patteson, Inc., 1996 Tour Brochure DARK MORPH 10) Brian PATTESON, Birding 28: 348 "Photo Quiz" (1996) DARK MORPH 11) Brian PATTESON, America’s 100 Most Wanted Birds. Michael O’Brien and Steve Mlodinow. Falcon Press. 1997. DARK MORPH 12) Alan BRADY, Seabirds of the World: The Complete Reference. Tipling and Enticott. 1997. DARK MORPH Unfortunately, only 2), 10), and 11) are rendered in the original color. The most recent article on North Carolina gadfly petrels (Brinkley, E. S. 1996. "Secrets of the Deep." Birdwatchers Digest 18.6: 66-‐72) has a photograph of a live "Herald" Petrel at the nest scrape with a chick, but it appears to be a P. [a.] heraldica light morph. Photographs of specimens have also been published. A photograph of David Lee's dark morph specimen from 20 August 1978 is not presented in his article, "Second Record of the South Trinidad Petrel (Pterodroma arminjoniana) for North America," American Birds 33.2: 138-‐139, but the first North American record/specimen (26 August 1933, found in a yard in Caroline Center, near Ithaca, in Tompkins County, New York) is included in a series of three specimens presented there, along with a light morph and an intermediate morph (from the large series collected by Storrs Olson at Trinidade). Murphy (1915. "Bird life of Trinidad Islet." Auk 32: pl. 25) offers dorsal and lateral views of a dark morph, a light morph, and a probable leucistic individual. The Indian Ocean form, generally reckoned as part of the nominate form but possibly sharing characters with both, appears in two photographs in a National Geographic Magazine article entitled "Mauritius, Island of the Dodo" by Quentin Keynes (1956, Vol 109: 100-‐101). In one photograph, the underwing of a dark or intermediate morph "Black-‐ webbed Petrel" is held up for inspection; in the other, a dark morph with a pale area at the base of the maxilla, sits on a nest scrape next to a hatchling. Neither is a particularly useful photograph, as each emphasizes the scenery and the researchers, but two good photographs, one of a dark morph and the other of a light morph with a chick can be found in Gill, F. B, C. Jouanin, and R. W. Storer. 1970. "Seabirds of Round Island, Mauritius." Auk 87: 514-‐521. Another photograph of the Indian Ocean form, this one of a dark morph with
entirely dark lores, is found in a note on conservation actions to protect the species (1993. "Overview." American Birds 43.3: 338). There is a fair quality still photograph taken from a short film shot in October 1959 at Hawk Mountain, Pennsylvania, by Donald S. Heintzelman, of a flying bird then identified as P. neglecta, Kermadec Petrel, which I and others believe to have been, more likely, Trinidade Petrel. Regrettably, the upperwing (which would aid identification immensely) is not visible in the published photographs. The conclusion of Gochfeld et al. (1988), consonant with that of Robert Cushman Murphy's assessment of the photographs as Kermadec (1959. Kermadec Petrel at Hawk Mountain. Linnean News-‐Letter 13.6:4), is apparently based on the underwing pattern. For more on this individual, see: Heintzelman, D. 1960. "Further comments on the Hawk Mountain petrel." Linnean News-‐Letter 13.7: 2-‐ 3, and Heintzelman, D. S. 1961. "Kermadec Petrel in Pennsylvania." Wilson Bulletin 73: 262-‐267. Photo on page 265. Nowhere in this account is the bird's upperwing pattern described, though Heintzelman shot 50 feet of Kodachrome film as close as 40 feet from the bird, "showing both the dorsal and the ventral surfaces of the bird." The film footage of that individual has not been available for perusal by any records committee and does not appear to be forthcoming; the copy at the National Museum has apparently gone missing (fide Paul DeBenedictis). Should the film become available again for review, it should be a straightforward matter to identify the bird, if the above is accurate. (Also widely available: Heintzelman, D. S. 1979. A Manual for Birdwatching in the Americas. New York. Universe Books. Photograph on page 54.) I have seen too much variation in both apparent (light-‐influenced) and actual underwing pattern in North Carolina's Trinidade Petrels to be convinced of that assessment. The underwing pattern of the Hawk Mountain individual can be seen, for example, in Michael Tove's published photograph of Trinidade Petrel; however, given that the neotype of Mottled Petrel, P. inexpectata, was taken in a farm field in Mount Morris, Livingston County, in upstate New York (between 5-‐10 April 1880) -‐-‐ without any apparent assistance by storm! -‐-‐ one leans toward extreme caution with records of out-‐of-‐range gadfly petrel records. One should consider all possibilities, no matter how apparently outlandish. There are many good unpublished photographs (Buckley, Patteson, Brady, Tove, and others) and many minutes of high-‐quality videotaped footage (Wiley, Pusser, myself) documenting Trinidade Petrel in North America. THE NORTH ATLANTIC RECORDS By my count, through 20 June 1996, there are 39 sight records from North Carolina (29 dark morph, 4 light morph, 6 intermediate morph, 1 light/intermediate). A roster of these records will appear in the article by Patteson. Some of these have not been reviewed by the North Carolina Bird Records Committee, which no longer solicits documentation on the species, as there are a sufficient number of reviewed records to establish the species' regular presence in small numbers in the deep water off the state's central coast. The above count includes birds identified to genus (in all but two cases dark birds) but which merited only the rank of "probable" Trinidade Petrel, or of "dark gadfly petrel" species. None of the latter showed differences in plumage or structure from the Trinidades studied
closely, but it seems prudent to flag some records as "probable" at this time. As has so often happened, the presumption that all dark gadfly petrels refer to P. arminjoniana could mask the presence of other taxa offshore. In addition to the North Carolina records, there is a record from Georgia (8 July 1993, an intermediate morph) and a 22 September 1991 record from Virginia, a dark morph individual studied by myself, Patteson, and others, a bird whose documentation has not yet been reviewed by the state avian records committee. Recently, on 13 July 1996, Robert L. Anderson and I observed two Trinidade Petrels, one light morph and one dark morph, in the lower Chesapeake Bay of Virginia, waifs from Hurricane Bertha, which deposited many other seabirds in the vicinity as well, among them at least 36 Black-‐capped Petrels. Outside the region but north of the equator, there is a 21 December 1905 [given as 31 December in Murphy 1936] record from the North Atlantic at 21 degrees 05' N, 43 degrees 35' W (Lowe, P. R. 1911. A Naturalist on Desert Islands), taken from the rigging of the sailing ship "Zenaida" after a gale. There is a (specimen?) record of Kermadec Petrel from Tarporley, Chesire, England, 1 April 1908; the record was rejected on grounds of improbability, as I understand it. Some have suggested that this individual was in fact Trinidade Petrel (see Witherby, H. F. et al. 1952. The Handbook of British Birds. Vol 4. Witherby. London. cf. page 63). A Trinidade Petrel "of unknown place of capture" was sold at Leadenhall Market, London, on 26 December 1899 (Palmer 1962). There is a tantalizing record from Lake Anna, Louisa County, Virginia, of two birds seen 5 September 1979 as a result of Hurricane David, described as dark tubenoses superficially resembling Sooty Shearwaters (there are currently about 8 records for Sooty Shearwater in the waters off NC and VA for summer and fall, notably fewer than there are for Trinidade Petrel) but with different flight styles (see Bazuin, J. 1983. "Hurricane-‐Blown Birds at Lake Anna in September 1979." Raven 54.5: 79-‐81). Given the (sub)tropical flavor of this hurricane's waifs (Bridled and Sooty Terns, Brown Noddy, White-‐tailed Tropicbird, Black-‐ capped Petrel, Band-‐rumped Storm-‐Petrel and the like), it would not surprise me if these birds had been dark morph Trinidade Petrels. Black-‐capped Petrels have been known to travel in tandem in hurricane winds, as evidenced by two, a male and a female, found together in Winchester, Frederick County, Virginia, on or about 31 August 1893 (Clapp, R. B. and J. F. Mehner. 1992. "Black-‐capped Petrels in the Mountains of Virginia." Raven 63.2: 90-‐92) and by the storm-‐blown Black-‐capped Petrels observed after Hurricane Bertha's passage through the lower Chesapeake Bay, 13-‐14 July 1996 in Virginia, in which many pairs (and one string of eight!) were observed. The only records I know of from the central Atlantic north of the equator are those of Richard Rowlett, who saw a dark morph at 18 degrees 29' N, 45 degrees 50' W on 13 March 1991, and on the same day saw a dark intermediate at 19 degrees 11' N, 46 degrees 39' W (personal log vol. 44, p. 5572). No other records of this species at sea, as far as I can ascertain, have been published, though Murphy did report seeing them at sea near the nesting islands, where the other expeditions undoubtedly saw them as well (pelagic birding as such was less discussed around the turn of the century than collection of the seabirds, of course).
FIELD IDENTIFICATION I will confine my remarks primarily to the dark morph, as this is most familiar to me. The videographic footage of a single light morph and the single intermediate morph provides no information on variation in plumage, and the Smithsonian Institution's collection of Trinidade Petrels is limited (see Appendix I). Furthermore, the paler morphs resemble nothing else that is likely to be seen off the coast of North Carolina, though two may have been confused with Mediterranean Shearwater. The dark morph is the trickster of the three: it can resemble both Sooty Shearwater and dark morph jaegers/skuas (Stercorarius spp.) far more than one might believe. Peter Harrison's Seabirds volume is absolutely correct in this contention: "in low wind speeds, flight can recall Sooty Shearwater" (p. 244). On many occasions, I have identified dark birds in the distance as "Herald Petrels," only to hear the cry go up, frequently from experienced pelagic birders, "That's just a Sooty Shearwater!" In the instances where the bird has been successfully pursued with the vessel, all have been Trinidade Petrels. (On one occasion, with a bird in the distance, I mistook a sitting dark morph jaeger for a Trinidade Petrel -‐-‐ and I might do so again in the future!) But there are aspects of Trinidade Petrels that remain constant, despite the potential for confusion, and these will be my focus in this first transmission. I will rely heavily on my field notes and on notes made from recent review of video tapes, rather than on memory. FLIGHT BEHAVIOR Now that "roller coasters" in American amusement parks have abandoned their classic sinusoidal structure, that term may have to be junked for describing the dynamic flight pattern of many larger tubenoses. The flight pattern of Trinidade Petrel becomes distinctive mostly in winds of 15 knots or greater. It arcs are typically very high, perhaps on average higher than those of Black-‐capped Petrels in similar conditions, but the arcs almost always appear to be higher because the ascent and descent of Trinidade takes place over a shorter space -‐-‐ in other words, the base of a given arc is rather narrower than the arc's base for Black-‐capped Petrel, both absolutely and relative to the height of Trinidade's own arc. This remarkable vaulting may have to do with the relatively longer wings of Trinidade Petrel, but whatever its cause it is certainly a consistent feature, in my experience, on days with a 15+ knot wind. Interspersed between these arcs, unlike with many Black-‐capped Petrels under similar wind conditions, Trinidade tends to flap two or three (rarely four) times before commencing its next arc. These flaps are not falcon-‐ or jaeger-‐like, nor do they resemble the wrist-‐driven, hectic-‐looking flaps of Sooty Shearwater in this flight mode. Rather, they have a more laborious look, with the flap coursing down the length of the wing more noticeably, as in Cory's Shearwater, more from the shoulder. In very high winds, that effect is lessened (and the flaps reduced sometimes to one or none), but we are not often offshore, intentionally at least, in high winds. Because Sooty Shearwater's arcs are not nearly as impressive as this -‐-‐ being much wider at the base, even in sustained 30 knot winds (as seen from seawatches) -‐-‐ the real point of confusion here
might be one of the smaller jaeger species, a dark morph, travelling dynamically, as they frequently do in winds of 20 knots or more, and occasionally in winds of 15 knots. The potential for confusion here may be substantial, and I would suggest one look to the bird's structure, rather than to flight style, in identifying a distant bird of this type (a closer bird will show differences in the underwing and upperwing pattern, and, with even closer birds, distinct differences in morphology). Usually, though, a young dark morph Long-‐tailed Jaeger/Skua will give itself away quickly by its buoyant, tern-‐like wingstrokes; likewise a dark morph Pomarine Jaeger would appear too broad-‐winged and heavy-‐chested. A dark Parasitic Jaeger may have the most potential to confuse, owing to its intermediate structure, and one can well imagine a dark morph passing a seawatch dynamically in the distance being taken for a dark gadfly petrel. We see few Parasitics well offshore, where the bulk of the Trinidade Petrels have been found, but quite a few adult dark morph Parasitics onshore, from the seawatches. In winds under 15 knots, and especially under 10 knots, one must study any dark bird very closely indeed. The high, narrow arcs disappear, and Trinidade Petrels travel rather more like other gadfly petrels when their Mother Wind is not blowing -‐-‐ a more pedestrian alternation of 4-‐5 deeper flaps with a shallow dynamic soar. In attempting to flee a boat (especially one full of yelling birders), the bird seems to increase the frequency of this pattern (that is, the periods are shorter) over that of the standard, point-‐to-‐point foraging flight pattern. (The differences between evasive maneuvres and other flight behaviors are too little noted by most East Coast pelagic birders, as are differences in flight behavior under different wind/sea conditions.) STRUCTURE It is interesting that G. M. Mathews (1936) proposed an alternate term (instead of "gadfly petrel") for the closely related species P. neglecta and P. arminjoniana: "dovelike petrels." The name has not gained currency, but certainly it deserves consideration. A Trinidade Petrel sitting on the water has a very distinctive shape, riding very high (as skuas do) in the water, with a dovelike shape, accentuated by a small head and (compared to Black-‐capped Petrel) a rather small bill. The breast seems bulky like a small jaeger's, and the neck tapers rapidly up to the small-‐appearing head. Mathews's term, however, was based on these species' habit of nesting above ground rather than in burrows (at the time, the nesting habits of P. ultima and others were not known) and their tolerance of handling by humans. Alan Brady's published photographs of a dark morph in flight shows a great deal. Even angled away, the bird's narrow wings and very long (in my judgment) "hand" -‐-‐ that rather scimitar-‐like curve to the outer edge of the primaries in particular -‐-‐ usually indicates a Trinidade in a stiff wind. A bird with the outermost primaries not fully grown in, or a bird widening the primaries in flight during low-‐wind conditions, will not show this shape as clearly (see Michael Tove's photograph, taken during a Beaufort Force 1-‐2). Peter Harrison's painting (Plate 22, 74c, dorsal, a small rendering) comes close to getting what I call the "archer's bow" quality of Trinidade's wings correct -‐-‐ that unmistakeable jizz when wings are tensed against the wind and the fluid, graceful lines emerge in their full splendor! Harrison's other three renderings look rather more like generic gadfly petrels,
much more like heavy male Black-‐capped Petrels than the Trinidade Petrels we see off North Carolina, which much more resemble the dorsal illustration 74c (see also the flight photo with Laughing Gull in the Gochfeld 1988 article). The cephalic projection always seems minor (about half) in comparison to the caudal (which tapers to a graceful point), and the bill is not noticeably heavy, though it is by no means petite (as in P. brevirostris or P. cahow). Harrison's bills look a tad deep compared to the North Carolina birds, but the Pacific specimens I studied have less imposing bills than Atlantic specimens, whereas the Indian Ocean specimens have rather larger bills than either. [Males in several gadfly petrel species have on greater culmen length on average -‐-‐ and sometimes deeper bills, with a more strongly arched maxillary unguis -‐-‐ than females (from my own measurements taken in 3 museum collections; see also Cruz, F. and J. B. Cruz. 1990. "Breeding, morphology, and growth of the endangered Dark-‐rumped Petrel." Auk 107: 317-‐326), but it is interesting that Murphy and Pennoyer (1952) found precisely this sexual dimorphism in Trinidade Petrel but not in the Pacific Herald Petrel.] PLUMAGE: DORSAL In fresh plumage, the bird is chocolate brown above, with a satiny or silken (one recent post used the term "velveteen") cast that catches the direct sunlight in uncommon and unpredictable ways. The plumage is darkest, nearly blackish brown, only on the mantle (not the entire back), the rump (not the uppertail coverts), rectrix bases (not the tips), greater and median coverts (not the lesser and marginal coverts), and outer primaries (not inner primaries and secondaries). This gives the bird a VERY sharp look above, especially in July and August (sometimes apparently earlier), after the complete molt, when the classic gadfly carpal-‐ulnar "M" pattern is apparent, usually fleetingly, as the bird/sun/birder orientation alters. David Abbott recently described this sheen or shimmer in the plumage as "Forster's Tern-‐like," and I think that is apt: Forster's Tern's plumage, quite unlike Common Tern's, has a shimmering quality that sets it apart from all other North American tern species, even at great distances. This sheen is common to many dark gadfly petrels and dark shearwaters but perhaps more prominent in some than in others. (I note that the "soft" plumage of gadfly petrels may in part be a defense against being gripped by small squid and octopus: I read this idea first in Ashmole, N. P. and M. J. Ashmole. 1967. Comparative feeding ecology of seabirds of a tropical ocean island. Peabody Museum of Natural History Bulletin 24: 1-‐131.) Sometimes, particularly on worn birds (some birds in May, for example), this pattern is pronounced, as the wear lightens the paler feather tracts (secondaries, back on either side of the mantle, uppertail coverts, and marginal/lesser coverts), such that the "M" is more consistently visible and the secondaries, in particular, may catch the light powerfully, taking on casts of golden-‐silver, depending upon the conditions. See Harrison's own remarkable photograph (Plate 163) of Murphy's Petrel, a bird presumably in postbreeding dispersal (in March; see Zimmer 1992) and thus with some feather wear: the secondaries fairly light up silver against the darker coverts. (I mentioned this pattern, in passing, in the field -‐-‐ and later over BirdChat -‐-‐ in discussing a possible Trinidade Petrel seen 27 May 1996, and it apparently generated some discussion, in transmissions I did not see, but I do stand by the description.)
I have communication from Dr. Michael Tove of Cary, North Carolina, that photographs (by himself and by Bruce Lantz of Delaware) of one of the 29 May 1994 dark morphs observed off North Carolina shows pale feather shafts in all nine primaries. I understood this feature to be diagnostic of P. neglecta, but I noted that shafts of the primaries AT THE BASE of the feather in specimens of Trinidade Petrel were indeed white, but on birds in fresh plumage, these bases are concealed by dark brown greater upperprimary coverts. I assume that birds in less than fresh plumage might indeed show this pattern of white primary shafts, and there may be more variation in this character than is presently known (see also Gochfeld 1988, p. 1258). Murphy (1915) notes that these white bases are exclusive to adults; juveniles have grayish feather bases and shafts. Have Australian pelagickers noted exposed white shafts in P. [a.] heraldica? And are Kermadec Petrels ever seen that lack the Pomarine Jaeger-‐like pattern of pale shafts and inner webs above -‐-‐ or that lack the pale areas of plumage around the bill? PLUMAGE: VENTRAL Still more complex. Harrison notes of darker morphs: "most [...] show typical underwings [i.e., like the ones he paints], but a few may show dark underwing with paler bases to primaries visible only when wing is flexed" (p. 244). The latter description fits Trinidade Petrel more than do Harrison's paintings (at least for the period May-‐August), as Harrison's illustrations all show largely WHITE underwings. Trinidades do usually show a pale undersurface to the primaries, but it is not always arrestingly white in true dark morphs, as Harrison paints, rather more silvery pale (with that sheen of satin), though some dark specimens show truly whitish greater underprimary and undersecondary coverts nearly as extensive as some of the lighter intermediate morphs. The outer third or less of the primaries is always dark, but the greater underprimary coverts can sometimes be more dark than pale, and often (especially visible with outstretched primaries) pale with with regular dark internal markings, such that there is a divided pale area in the underprimary area (cf. Tove's photograph). [In no case is there is a clear double undersecondary "bar" created by pale bases to the secondaries and pale greater undersecondary coverts (with the same doubling effect by virtue of regular dark internal markings in these coverts), such as Harrison paints, but the underwing coverts on the flat skins I investigated were rather in disarray, and I cannot discount this pattern, which I have not seen clearly in the field. The photograph of a Trinidade Petrel by Patteson in Birding magazine does hint at this pattern.] Thus, the dark morph illustrated in ventral aspect by Harrison would be paler than any dark morph Trinidade we have recorded but near the pale end of the extreme. Under no circumstances have we detected white or pale marginal coverts (= the leading edge of the wing) in any dark morph of Trinidade Petrel. This distinguishes all dark birds recorded off North Carolina, Georgia, Virginia (as well as the New York specimen) from all of Harrison's illustrations. The dorsal illustration 74c shows no such mark -‐-‐ if this mark is supposedly visible only from below in P. [a.] heraldica, then I suspect that Harrison intended to portray lesser coverts rather than lesser and marginal coverts together. Gadfly petrels don't seem to possess much in the way of marginal coverts as far as I can tell -‐-‐ the lesser coverts on either side of the wing nearly meet -‐-‐ so perhaps this is moot. Lesser underwing coverts are indeed pale, or at least partially so, on pale morphs, both of the nominate and of the Pacific birds in the Smithsonian collection, but they don't extend onto the leading edge of
the wing, which is dark. Plate 9e of P. C. Harper and F. C. Kinsky's Southern Albatrosses and Petrels [1978. Price Millburn. Wellington] distinguishes between very narrow dark marginal coverts and pale lesser coverts. Pale lesser coverts can be seen in the Patteson 1994 photograph of a light morph. The light tones on the underwing are somewhat light-‐ dependent. A bird arcing high (and thus nearly perpendicular to the ocean's surface), exposing the underwing more directly to the sun, may really "light up" below, whereas a bird in low winds might gain only a 60-‐degree angle to the ocean's surface and thus appear duskier below. (See 1991 photograph of P. ultima by Don Roberson [American Birds 45.3: 511], taken off California 11 April 1991: the bird shows one underprimary region in shade, the other "flash[es] white in direct sunlight.") There is genuine variation in this underwing among the birds we observe, though, some of which relates to molt, some of which clearly does not. None of the specimens in the Smithsonian show an all-‐dark pattern like that of P. incerta or P. rostrata (comparative photographs taken), and there is not a great deal of variation in the pattern of the dark morphs: most have greater underprimary and greater undersecondary coverts pale with dark areas in the distal portion of the feather, so that there is a bar of pale feathering in the underwing, widest at the "hand" or the carpal joint, where it is in some cases "divided" from the pale undersurface of the primaries by these dark areas on the coverts (many gadfly petrels seem to have these dark internal areas on underwing coverts, including P. cahow and to a lesser extent P. hasitata). A pale secondary "bar" on the underwing is evident on several Smithsonian specimens, despite the disarray of some of the coverts. The head, throat, and facial area appears as a concolor chocolate brown, unlike many other similar species which show white at the base of the bill, and the underparts are similarly uniformly colored. Several dark specimens, however, show a hint of white in the area of the throat, particularly around the base of the lower mandible. This is produced by wear, in part, as the bases of the body feathers are white, but it also probably part of normal gradation toward the darker intermediate forms. This has not yet been observed at sea on "dark" morphs off North Carolina; it should be a caution to those considering dark gadfly petrels in this region for species other than Trinidade Petrel. We have also never seen a Trinidade Petrel of any morph at sea with pale areas of plumage at the base of the maxilla. Leg color in this morph appears to be all-‐dark as observed in the field (I have noted leg color only on two or three individuals). It is clearly all-‐black in all specimens I examined, including the two dark morphs from Round Island. PALER PLUMAGES/MORPHS I have too little field experience to compare the Atlantic and Pacific/Indian ocean taxa here, but I include, as a point of departure, a review of the Smithsonian's skins in Appendix I. Above, the light morph I have seen looked little like Harrison's dorsal painting 74a: it lacked a white nuchal band or collar and showed no white posterior to the naricorn or in the loral area generally. The carpal-‐ulnar "M" was not pronounced, but with only one observation, this means very little (this is a highly variable feature in Black-‐capped Petrel at any time of year, for instance). Below, the bird looked unlike anything illustrated anywhere. Pale plumage actually dominated the underwing, with dark plumage really limited to just the median underwing coverts and a few stray speckles, but nothing like the
tiered dark/light/dark/light/dark/light pattern that Harrison illustrates. Patteson's 1994 photograph shows the underside to good advantage. The underwing pattern observed now twice in the field to good advantage off North Carolina corresponds nicely to the flat skins in the Smithsonian collection, which show inner underwing lesser coverts pale (or mottled pale), just enough to set off the brownish median coverts as an incursive "bar" in the otherwise pale field of the underwing -‐-‐ not as striking as the nearly black bar in a field of white one sees in a Black-‐capped Petrel (or many Pacific species, e. g., P. cervicalis), to be sure, but not dissimilar.
Appendix I: NOTES ON SPECIMENS AT SMITHSONIAN INSTITUTION USNM Specimen Number precedes all descriptions of individuals Accounting of skins I looked at: ATLANTIC OCEAN FORM: 3 flat skins (dark morph) 4 round skins (dark morph) 3 round skins (light morph) 4 flat skins (light/intermediate morph) 1 round skin (intermediate morph) 1 round skin (dark intermediate morph) (I did not look at skeletons or pickled individuals.) INDIAN OCEAN FORM: 1 round skin (light or light intermed.) 1 round skin (intermediate morph) 2 round skins (dark morph) PACIFIC OCEAN FORM: 5 round skins (light morph) 1 round skin, open wing (light morph) 1 round skin, spread wing (light morph) 2 spread wings (no skin) 1 round skin (lighter intermediate morph) ***NO DARK MORPH PACIFIC FORMS PRESENT*** I. ATLANTIC AND INDIAN OCEAN DARK MORPHS Very little variation in these birds, and no departures from our experience with them offshore. The Atlantic specimens are slightly larger (in bill dimensions and overall body length) than the Pacific birds, noticeably smaller than the two Indian Ocean birds, although I did not try to quantify this with such a small sample size to work from. Legs and feet are always dark in this form, and the distinctions between slightly darker tracts of covert feathers and slightly lighter areas are subtle at best under museum lights. Murphy (1915) notes that juveniles of the dark morph on Trinidade differ from the adults in having the "concealed portions of the feathers light gray with dark shafts," whereas the adults have "the concealed portions of the feathers [...] pure white, including the shafts." There is no other conclusive information on aging any morphs of the species offered anywhere that I can find.
Specimens 527619 and 527610 are very similar, being all chocolate-‐brown, with a small (less than 5% of area) scattering of paler feather bases visible in throat. As these darker birds wear (I include darker intermediate morphs here), I suspect that as the paler bases of the body feathers become more and more exposed, a given individual's appearance could change appreciably through the year. 348070 is the Cornell University #4947, Arthur A. Allen's hurricane-‐driven 1933 specimen (1934. "A New Bird for North America" Univ. of the State of New York, Bulletin to the Schools 20.13: 134-‐135). Nice to finally see it! It is uniformly dark above and below, as is 527618, another of Olson's from Trindade. The sole Indian Ocean birds, 487226 and 487229, from Il Ronde (Round Island), Mauritius, were both larger than all the other dark morphs in the collection, with larger bills. In the former, the pale bases to the rectrices (only about 15% or so of the feathers) were exposed on the dorsal surface -‐-‐ enough such that they might appear in the field. This may have been because the uppertail coverts were a bit in disarray. Nevertheless, potential (in the North Atlantic) for confusion with P. caribbaea was high: the Institution has two Jamaican Petrels in its collection, 80859 and 80850, both taken 17 November 1879 at the Cinchona Plantations, S. Andrews, W. Rock, Jamaica, by Edward Newton, who also supplied the A. M. N. H. with its sole specimen, 437721, which I studied last December [Imber (1991) lists 23 other specimens of this form]. Proportions of the two taxa are different enough that one hopes, under good field conditions, the two could be distinguished. None of the Atlantic birds showed as much white in the rectrix bases, and none had any white exposed here. Photographs in Keynes (1956) and Gill et al. (1970) show dark morphs with pale feathering around the base of the maxilla. This is not evident in dark morphs from the South Atlantic in the Smithsonian collection, nor have we noted it at sea off North Carolina. Interestingly, the Indian Ocean form is listed on all the museum's tags as "P. a. arminjoniana," and Murphy and Pennoyer (1952) note that it is "quite indistinguishable from South Atlantic examples." Storrs Olson said this may require reevaluation. Though most plumage characters of the two lighter Indian Ocean skins more closely resemble the Atlantic form, other characters suggest the Pacific form (see below). I wonder whether (given the genetic isolation of Pterodroma populations) these may not constitute a separate taxon, or whether there is indeed (still?) gene flow between these Indian Ocean birds and either or both other populations. II. ATLANTIC OCEAN PALER MORPHS I studied and photographed 527614, 527616, 527617, 527615, and 527621, all prepared by Olson, in addition to several flat skins. Common to all were pale legs and feet, with two-‐ thirds of the distal portion of the foot black. All were medium brown above, with little variation among them, although the one worn bird (527615) was clearly a shade paler above than all the rest, owing to this wear. Of these five, three seemed to be "light" morphs like the 1994 Patteson photograph (the pale throat of that bird is difficult to see in that photograph), one was an intermediate (527614), another a dark intermediate (527621). All birds show dark lores; none had any pale feathering around the base of the culmen, as in Pacific birds.
The intermediate, 527614, has throat and facial area mottled white and brown, the breast banded lightly with brown feather edges, the belly mottled with about half each of brown and pale feathers visible. What could be seen of the underwing indicated extensive white in the underprimary area, as in the 1994 Patteson photograph. A few paler bases of nuchal feathers visible but certainly not collared. The darker intermediate, 527621, has a belly mostly brownish, with some gray component, with the paler feather bases most noticeable here, much less so on the breast. The throat is quite dark on this one, with pale feather bases here quite tough to see, only a few scattered. Not much of an appearance of a pale throat, as in the paler morphs. The undertail coverts show only about an eighth white, the remainder dark, as in 527614. This is the darkest example of an intermediate in the collection. The lightest birds, 527616, 527617, and 527615, are fairly similar. The first shows the flanks mottled brown, the sides a paler brown, with a light brown, faint breast band; the belly and upper throat are white, the lower throat with brown, slightly grayish-‐brown, tips to the feathers, and the undertail coverts pale with dark tips. In the second, the flanks are very heavily dark brown and the warm gray-‐brown sides correspondingly more heavily marked than the first; the facial area is a darker brown, the throat white with scattered brown tips. The most arresting feature of this individual is the very neat 5 mm wide necklace setting off the white throat -‐-‐ looks like a White-‐throated Magpie-‐Jay! The third has a light belly with flanks heavily marked with medium brown, a white throat with some scattered light brown tips, and a mottled light brownish, diffuse breast band. The description of the Snowy-‐mantled Petrel, which Murphy was later to call a "freak," is disturbing in a number of respects. First, at least two dimensions of the bill seem diminutive in comparison to other Trinidade Petrels, closer to that of Herald Petrel, namely those of the maxillary unguis, also called superior unguicorn or greater unguis, and the basal depth of the bill. Second, most of the bill was bright pink or flesh-‐colored in life (with the exception of the unguis, which was black). Third, it has a shorter tarsus and longer foot than all other specimens of Trinidade Petrel Murphy examined. The contrast between its dark crown, lores, and ear covert and its snowy body plumage, coupled with dark upperwing, pale underwing (except for trailing edge and the leading edge of the primaries), and dark tail, make it a most striking bird. From Murphy's (1914) description, the symmetry of the dark markings in around the mantle was fearful: "Hinder cervix and interscapulum white, the feathers with dark shafts, faint anteriorly, which expand to form conspicuous rhomboidal speckles on the middle and lower back; scapulars white with dark shaft streaks, the exposed portion of outermost dark" (p. 13). III. INDIAN OCEAN PALER MORPHS Only two such birds in the collection, neither of which showed the pale loral patch of the 1956 photograph in National Geographic magazine. Pale lores appear to be distinctive in
the Pacific taxon but were present in none of the paler morph specimens from the Atlantic in the collection. Specimen 487225 is a light or light intermediate, large and bulky, with a very dark chocolate brown breast with a very restricted white throat patch (unlike any of the other skins), the belly and lower breast off-‐white (not white) with the tips of these feathers finely vermiculated with gray. This is intermediate between Types 2 and 3 as delineated by Gill et al. (1970), who found all-‐dark birds (Type 1) to be twice as common as birds with a dark throat and upper breast with a white belly (Type 2) -‐-‐ not a pattern present in the Smithsonian series Trinidade Petrels -‐-‐ and six times as common as birds with "white below (occasionally with gray vermiculations), including the throat," which are the rarest (Type 3). The undertail coverts show the same vermiculation. This gray, as opposed to brown, pigmentation is characteristic of all the Pacific Ocean specimens (see IV. below) but is present on no birds from the South Atlantic. 487224 is similar but darker, an intermediate, with a predominantly gray-‐brown belly with only scattered white feather bases visible below. Undertail coverts similar but darker overall, perhaps two-‐thirds dark. The photograph of the adult "light phase" in Gill (1970) shows fine speckling in the lower part of the face, more like heraldica. IV. PACIFIC OCEAN PALER MORPHS I reviewed 487223, 496098, 487228, and 497725. All show whitish lores mottled with distinctly gray interiors to many feathers, lending a "salt-‐and-‐pepper" speckled effect to this area. A perfect close-‐up photograph of this aspect is found on page 2 of John Warham's The Petrels (1990. London: Academic); note also the tiny bill on this form in the photograph. The same speckled effect is true of the facial area in several specimens. The crown is dark in all, in most distinctly moreso than the back (Harrison's dorsal collar is thus conceivable for this form), with two specimens (497725 and 496098) showing some paler feathering in the crown between the eyes. All specimens have a grayish ("almost a bluish-‐gray component" -‐-‐ Olson) cast to feathers of the back, upperwing coverts, and body feathers, which none of the Atlantic birds possess, and all likewise show pale undertail coverts with extensive and very fine grayish or gray-‐brown vermiculation. The first specimen, nearly an intermediate, shows a very distinct crown (nearly a cap), with very dark flanks. The second has a pale belly with very strong, heavy vermiculation more reminiscent of an owl than a Trinidade Petrel (this individual could be easily termed a paler intermediate morph). This type and color of vermiculation is not seen on the Trinidade Petrel skins. The third has a very dark crown of solid color. Its sides are very mottled with gray (reminds me of the grays of P. mollis body feathers) and the pale belly shows extensive gray vermiculation. The fourth shows nearly a full breast band, albeit a very diffuse one, of gray vermiculation. The belly is contrastingly pale, with flanks and sides heavily mottled in dark brown. Appendix II: Voice We have heard Black-‐capped Petrel vocalize at sea only once (an apparent distress call) but never a Trinidade Petrel. Roger Clapp described the Pacific Herald Petrel's call (which he heard on French Frigate Shoal) to me as "precisely like the FLEEK-‐ah FLEEK-‐ah FLEEK-‐ah of the Northern Flicker." (We have taped very similar calls in Bermuda Petrel in 1993,
heard both on the burrow and following the long antiphonal courtship tremulo of one bird, sex of the caller unknown.) Palmer (1962) cites Newton's (1956. Ibis 98: 296-‐302) description of the birds at Round Island, Indian Ocean, as beginning "like the chatter of [Eurasian] Kestrel, and deepened to a chuckling tee-‐tee-‐tee-‐tee-‐tee too-‐too-‐too-‐too-‐too." That form's call in described in Gill et al. (1970) as a series of "ki" syllables delivered in rapid series followed by "lower, melodic oscillating 'k-‐lu' notes" (spectrogram included). Another call is described as a "harsh descending kree kree kree kree kree kree." Murphy (1936) describes Trinidade Petrels as "chattering with voices not unlike those of terns." These may all be similar calls. If feather lice, DNA, and intestinal coils are used to render taxonomies of gadfly petrels, call-‐types should be considered as well? There is spectrographic analysis of Pacific birds' calls birds from the Pitcairns in the Brooke (1996) article; are there any recordings of Marquesas, or Round Is., or Trinidade birds out there? Appendix III: Leg color Lowe and Kinnear (1930) based their division of the Trinidade Petrel into three morphs on leg and foot color. The light phase has white legs and feet with mostly black webbing; in the intermediate the white is replaced with pink; in all dark morphs, the entire leg and foot are black. The Indian Ocean morphs appear to show the same pattern of pigmentation in foot and leg (Gill et al. 1970). Gochfeld et al. (1988) note contra Murphy (1936) that "our examination of the A. M. N. H. specimens reveals that the light phase as well as the dark phase of P. a. arminjoniana have all-‐black soft parts" (p. 1256). This is not at all true of the U. S. N. M. specimens, all the light morphs of which (from the Pacific, Atlantic, and Indian Oceans) have pale or pinkish legs (along with the basal portion of the foot. (Could anyone with access to the American Museum check on this?) One distinction between Pacific birds and others is that their dark morph is said to have bicolored feet, which the dark morph Trinidade supposedly never has. (This confirmed by Dr. Voisin of the Paris Museum, below.) Appendix IV: Trivia Like many seabirds nesting near the equator, Trinidade Petrel's nesting appears to be staggered through the year: Murphy (1936) mentions that Wilson found eggs in September, and downy young but no eggs in July. This means that birds in the North Atlantic are likely to be in various plumages at any given time, and indeed one dark morph seen off North Carolina on 29 May 1994 was in fairly heavy molt of the remiges and coverts, whereas another seen the same day seemed in fairly fresh plumage, perhaps a juvenile. There may be a postbreeding and/or postfledging dispersal into our area in late May (accompanying the northward migration of terns, shearwaters, storm-‐petrels, phalaropes, South Polar Skuas, jaegers), but these birds may well be present year-‐round, as are some numbers of
Black-‐capped Petrels. Too few excursions off North Carolina have taken place during January through early May, or from late October through December, to speculate. (The abundance of Black-‐capped Petrel during contranuptial dispersal in December [discovered by David Lee] is somewhat misleading, as the species is not particularly numerous in the rest of the winter off North Carolina.) The first North American record was taken at Caroline Center, New York, on 24 August 1933. The bird was alive and was force-‐fed pieces of fish. It eventually learned to pick up dead minnows out of a pan of water, but it never tried to catch live ones. It died after about eight days. (These days, small fresh squid might be available, should anyone reading this happen upon a live Trinidade Petrel in your backyard.) Storrs Olson jokingly suggested changing the name back to Arminjon's Petrel (from Murphy 1915) or better still, after the co-‐discoverers: "Giglioli and Salvadori's Petrel." (For North Americans still struggling to pronounce "Fea's Petrel," this would be my personal choice.) ACKNOWLEDGEMENTS I want to thank Angus Wilson for meticulous editing of this document, Storrs Olson for assistance at the Smithsonian, and Brian Patteson for his review as well. INTERNET RESPONSES TO THIS DOCUMENT I. From Chris CORBEN
[email protected] Tue Jul 9 04:55:39 1996 To my question: > I am interested to hear anything you may know about dark morph Pacific Herald Petrels (I see in the HANZAB that you have seen the only one in that vicinity) -‐-‐ I hear a rumor that they will be split from paler morph Heralds.
The response: "It was a long time ago -‐ 1981 I think. This bird was really dark. At first I thought it was going to be a Sooty Shearwater. I saw it in rather marginal light, but I did see the narrow white under the leading edge of the inner wing, and white extending from the bases of the Ps in a narrow line down the ?median coverts, angling towards the rear of the wing near the body. The wings looked narrow to me and fairly straight with the tips angled back quite markedly. At the time, I didn't have much experience with Pterodroma, and I hadn't yet seen Kermadecs. The primary shafts certainly showed no white. I realise it is said that some Kermadecs can lack the white shafts, though I have never seen such a bird. I think Kermadec has a very different shape from a Herald, though it is also a master of flexibility in this respect. I totally disagree with the opinion that Kermadec has narrower wings than Herald -‐ I would say just the opposite. In fact, to me, Kermadec looks especially broad-‐ winged and short tailed for a Pterodroma, though in strong wind, of course, it can look more slender winged with the wings more angled forward to the wrist and back beyond, in which case the resemblance to a small skua/jaeger can be remarkable. The impressions I have had from seeing many Kermadecs is that they would not likely look like that bird. They would look shorter tailed and more angle-‐winged if the wings looked so narrow. Also, although Kermadecs are very variable in plumage, I would not expect to see one which showed white on the secondary coverts without showing much more white on the primaries." Chris Corben PO Box 128 Olema CA 94950
[email protected] II. From: Jean-‐François VOISIN Laboratoire des Mammifères et Oiseaux Muséum National d'Histoire Naturelle 55 rue de Buffon 75005 Paris -‐ France [Brinkley's comments in brackets within the letter] Dear Dr. Brinkley, Thank you very much for your mail of 10. July which Dr. Bed'Hom passed to me. Your French is excellent, you must have been pretty good at it at the high school! I have examined our specimens of Pt. arminjoniana, you will find their descriptions below. As you know, the dark parts of pale individuals are grey, whereas the ones of dark individuals are dark brown. Even if a blue or bluish colour is often the result of light diffraction on small particles of melanin, I think that it would be interesting to know if
different pigments are involved in the two cases. The fact that brown individuals have less white than grey ones may have another genetic determinism. Pterodroma arminjoniana in the Muséum National d'Histoire Naturelle, Paris. I.-‐ N° 1936-‐3 1. Paper label of the MNHN : Pterodroma heraldica paschae Lönnb. -‐ îlot Motu-‐nui (près île de Pâques) -‐ coll. : Dr Draphin -‐ 21 novembre 1934. Ad. m. [Easter Island race paschae of Herald Petrel, taken at Motu-‐nui islet, near Easter Island.] 2. Label of the collector (now difficult to read) : ojos : azul grisaceo -‐ patos rosadas -‐ dedos negros, pico negre. [Eyes grayish-‐blue, legs rosy, feet black, bill black.] Specimen in intermediate plumage, not in a very good state. Head brown, a little greyish on the sides, loral region hardly lighter. Neck brown (tip of the feathers more greyish), the same colour as the sides of the head. Feathers between the rami and on the throat whitish, very narrowly barred with grey on the lower throat. Foreneck with white feathers largely bordered with black at the tip, giving probably an all-‐ brown appearance in life. Back, tail, upperwing and thighs brown. Upper breast and flanks greyish brown, lighter than the back. Lower breast and belly with a narrow (about one inch broad) greyish white stripe (feathers greyish at the tip). Undertail coverts whitish at base. Lesser underwing coverts dark, more or less greyish brown. Greater underwing coverts whitish at base, mainly so on the inner web, brown at least on the 1/3 tip, building a narrow pale zone parallel to the border of the wing. Primary and secondary remiges whitish at base, making a fairly large pale area. Legs yellow (according to labels : pink in life), feet black from the end of the first phalange of digits 2 and 3, digit 4 all black above and below, but yellowish on the external side of the first phalange. Bill black. Culmen : 26.1 mm ; Hook from nostrils : 16.5 mm ; wing : 280 mm ; tarsus : 33 mm ; tail : 88 mm. [This sounds very much like the Herald at the Smithsonian Inst., although the reduced amount of pale plumage in the lores is very interesting, a bit more like the Indian Ocean nesters.] II.-‐ N° 1963-‐634. 1. MNHN label : Pterodroma arminjoniana heraldica (Salvin) -‐ Loc. Océan Pacifique 2°50 S 129° W -‐ 15 mars [March] 1922 (female) 2. American Museum of Natural History label : 191 662 -‐ lat 2°50.S-‐long 129°W -‐ WG (female) R.H. Beck -‐ Whitney So. Sea Ex. -‐ iris brown -‐ bill black -‐ feet black, upper third & tarsus whitish -‐ Sexual organs : nesting -‐ 2351. All dark brown, hardly lighter below, the feathers laterally behind the upper mandible and shortly before the eye narrowly edged with whitish, giving a lighter appearance (inconspicuous from a distance). The same, but more pronounced, on the forehead. The same also for the feathers between the rami and on the throat, which are larger and have a broader light edge, giving the appearance of a small light grey area merging progressively into the surrounding dark plumage. It is doubtful if this light area is visible in the field, except under extremely good viewing conditions. Underside of the wings all dark. Legs and feet like the Easter Island specimen. [If the legs and feet are like the Easter Island specimen, then this is different from the Atlantic taxon in the dark morph, which has entirely black legs and feet. Could it be that this feature is somewhat age-‐ dependent, as in jaegers/skuas Stercorarius?]
III.-‐ Pale specimens from the Indian and Pacific oceans. -‐ 1966-‐2446 Île Ronde, Mauritius. The feathers in the loral region bear a more or less complete light, narrow terminal band. This may be visible in the field as a slightly lighter area. -‐ 1966-‐2444. Ile Ronde, Mauritius. A small, paler area in the loral region where the feathers have a light edge. This is surely visible in the field, but is far less pronounced than in the Pacific Ocean birds.-‐ 1963-‐633. Oeno, Polynésie. Large and well individualised lighter areas in the loral region and on the lower forehead, the whitish color of the foreneck going up around the base of the bill and merging progressively with the surrounding grey colour. -‐ 1975-‐1764. Marquesas. Large and very distinct whitish area in the loral region and on the forehead. -‐ 1975-‐1966. Marquesas. The same. -‐ 1975-‐1967. Marquesas. The same. -‐ 1975-‐1768. Marquesas. The same, but less marked, a few darker feathers behind the gape. -‐ 1975-‐1765. Marquesas. The same as the above bird. -‐ 1975-‐1769. Marquesas. Small, distinct paler area. There does not seem to be any relationship between the size and distinctiveness of the paler area in the loral region and the sex of the birds. III. From Macklin Smith
[email protected] Fri Oct 4 15:45:24 1996 Received: from breakout.rs.itd.umich.edu by sun.pcmail.Virginia.EDU (8.6.10/1.34) id PAA17274; Fri, 4 Oct 1996 15:45:24 -‐0400 Received: from localhost by breakout.rs.itd.umich.edu (8.7.5/2.3) with SMTP id PAA08592; Fri, 4 Oct 1996 15:45:22 -‐0400 (EDT) Date: Fri, 4 Oct 1996 15:45:21 -‐0400 (EDT) From: Macklin Smith X-‐Sender:
[email protected] To: Ned Brinkley Subject: Michigan specimens Message-‐ID: MIME-‐Version: 1.0 Content-‐Type: TEXT/PLAIN; charset=US-‐ASCII Status: ORr Ned -‐-‐ I checked the Michigan range today for Pterodromas, especially Herald. Not much of a collection, but included 3 Heralds and 4 P. mollis and 1 P. feae. The latter looked just as one would expect, and was collected March 1, 1924, at Sao Nicolo in Cape Verde Is. In the same tray-‐-‐only one tray of Pterodromas-‐-‐was a Bulwers Petrel, which I held and beheld. Two of the Herald Petrels were indeed taken on the Blossom So. Atlantic expedition. A dark bird was originally Cleveland Museum 125, now U of M 130285, and was taken Dec.
28, 1926, by Allen Moses, Waterfall Valley, S. Trinidad; a female. A light bird was Cleveland 145, now U of M 130286, and was taken by Allen Moses and Robert Rodwell (?) at Cascade Valley, S. Trinidad, on Dec. 29, 1924; a male. The first is labeled P. trinidad-‐ or arminjoniana; the second, P. wilsoni [arminjoniana]. The third bird in the collection is labeled as P. arminjoniana and was taken at Mauritius, also in the twenties; it has a dark brown back mottled with white at nape, chin gray becoming white at the neck, gray breast band, belly white heavily mottled gray, flanks dark. No Pacific birds. DARK ATLANTIC BIRD Upperparts dark brown with, however, some very light gray mottling beginning at nape and extending onto mantle. Primaries dark brown; faint gray mottling on coverts; secondaries showing dark brownish gray on inner vanes. Unerparts dark grayish brown with a little gray mottling on lower neck. General appearance of an all brown bird. LIGHT ATLANTIC BIRD Upperparts dark brown, but with gray mottling, irregular and sparse, on the nape; faint gray stipples bordering maxilla; gray flecks as well in ocular region, on brown, lightening downward gradually into lower cheek. Primaries dark brown; rest of wing brown but with some gray mottling on coverts and with the secondaries showing graying on inner vanes. Chin mostly white with faint brownish bars (like the lightest Common Cuckoo); complete breast band of gray interspersed with white; belly white, washed with gray; dark brownish gray flanks; vent area white; tail dark brown. Manipulating the feathers of back and breast on both of these specimens, I noted that the individual feathers were mostly white. Evident plumage depended on the characteristics of the tips of the feathers-‐-‐and this underscored for me just how fluid the plumage characteristics of this species must be. Why is another question. Macklin Smith University of Michigan
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