Proposal (428) to South American Classification Committee

 

Add Puffinus tenuirostris (Short-tailed Shearwater) to main list

 

Effect on South American CL: This transfers a species from the Hypothetical List to the Main List.

 

Background: The Hypothetical List currently reads as follows: "Records from Peru and Chile refer to misidentified specimens of P. griseus (Eisenmann & Serventy 1962)".

         In fact, these records were two not yet published (in 1962) nineteenth century specimens of Puffinus griseus, but labeled as P. tenuirostris, deposited in European museums and achieved in the Pacific Coast of South America (Callao [Peru], and “Chili”).

 

Published evidence: On May 28, 2005, a petrel was found at Stella Maris beach, Salvador city, State of Bahia, Brazil (12°55’S, 38°31’W).

 

The specimen of this petrel was photographed, measured and subsequently taxidermized and deposited in the particular collection of Rolf Grantsau (Sčo Paulo) under number 10.741.

 

Black-and-white photographs and table of measurements are available in Souto et al. (2008).

 

This same record was previously reported by Lima (2006).

 

Further remarks:

 

Michael Imber and Bernard Zonfrillo were consulted and made the specific identification of the photographs.

 

This documented record was accepted by the “Comitź Brasileiro de Registros Ornitológicos” (CBRO).

 

This Brazilian record is not the “first record to the Atlantic Ocean” as stated by Souto et al. (2008). Brian Sullivan (per Remsen) pointed out that there, at least, two were previous records for the Atlantic: a sight record off Virginia on 18 January 1998 (Brinkley et al. 2001) and a specimen obtained off southwestern Florida on 7 July 2000 (Kratter and Steadman 2003).

 

Literature Cited:

BRINKLEY, E. S., J.B. PATTESON, and C. TUMER. 2001. Short-tailed Shearwater (Puffinus tenuirostris) at Norfolk Canyon. Raven 71: 84-89.

 

EISENMANN, E., AND D. L. SERVENTY. 1962. An erroneous Panama record of Puffinus tenuirostris and other misidentifications of P. griseus.  Emu 62(3): 199-201.

 

KRATTER, A. W., AND D. W. STEADMAN. 2003. First Atlantic Ocean and Gulf of Mexico specimen of Short-tailed Shearwater. North American Birds 57(2): 277-279.

 

LIMA, P. C. 2006. Aves do Litoral Norte da Bahia. Birds of the northern Coastal region of Bahia. Available on: www.ao.com.br/downlad/lnbahia.pdf

 

SOUTO, L. R. A., MAIA-NOGUEIRA, R., AND D. C. BRESSAN. 2008. Primeiro registro de Puffinus tenuirostris (Temminck, 1835) para o Oceano AtlČntico. Revista Brasileira de Ornitologia 16(1): 64-66.

 

José Fernando Pacheco, March 2010

 

 

Comments solicited from Brian Sullivan: “Based on the specimen's apparent round head, short bill, and bold white throat, this individual looks good for Puffinus tenuirostris, but details of the underwing pattern would have been helpful to confirm the identification. Nonetheless, this bird looks typical of Short-tailed Shearwater in all respects based on what we can see in these photos. Having not examined the specimen myself, I give it cautious endorsement.”  Brian also noted that there is a specimen from the Atlantic:  Kratter & Steadman, 2003, N. American Birds 57(2): 277.

 

Comments solicited from Steve Howell: “Looks fine to me.”

 

Comments solicited from Dr. Stephen F. Bailey: “I have looked at the paper by Souto et al., with its photos and measurements, about their record of Puffinus tenuirostris.  Although I cannot read Portuguese, it is clear to me that the bird really is a

Short-tailed Shearwater (Puffinus tenuirostris).

 

“First, the photos do look like that species.  The bill size in relation to the reference Sooty Shearwater shows the typical relationship.  The blacker cap and whiter throat are typical, but not universal, of Short-tailed Shearwater.  Although it is probably of no use in this case due to specimen preparation variations, even the steeper forehead that seems to show here is typical of Short-tailed Shearwater.  Having said that it LOOKS like a Short-tailed Shearwater, it is time to examine the measurements for critical confirmation.

 

“The measurements generally confirm that the specimen is a Short-tailed Shearwater, although there are some questions about some measurements.  For reference I used the measurements published in Volume 1 of "Handbook of Australian, New Zealand, & Antarctic Birds" (HANZAB) -- page 630 for Sooty Shearwater (Puffinus griseus), page 642 for Short-tailed Shearwater (Puffinus tenuirostris), and page 646 for Christmas Shearwater (Puffinus nativitatis).  More on the latter species later.

 

“BILL (culmen length):

The culmen length of 31mm is just right for P. tenuirostris.  However, the authors' average culmen length of 55 mm for three P. griseus is far too long for that species and does not seem to fit with the relative lengths in the photograph.  I can only think that "55mm" was a typological error for "45 mm."  Even measuring the culmen in a different manner (e.g. from skull versus exposed), it would seem difficult to add 10 mm -- and then how would the P. tenuirostris culmen length come out as only 31 mm?  That measurement is a full 10 mm shorter than the shortest P. griseus listed in HANZAB.  If the method of measuring the culmen did in fact overestimate the culmen length by usual methods, then the 31 mm culmen is even farther out of range for P. griseus.  Thus the bill length would seem to indicate P. tenuirostris, but there is a lingering question about the bill measurements, especially for P. griseus.

 

“WING LENGTH:

The wing length of 262mm is at the bottom end of the range for P. tenuirostris (261mm is the lowest listed in HANZAB, from a sample of 66 birds).  However, it is also just within the range listed for P. griseus (260 mm is the lowest listed in HANZAB, from a sample of 22 birds).  On the other hand, the mean wing length for P. griseus is very close to the mean given in the paper (297.6mm), versus the mean for P. tenuirostris close to 275 mm.  Thus the 262 mm measurement should be much less exceptional in P. tenuirostris than in P. griseus.  The next-shortest wing in the HANZAB sample of 22 P. griseus was 281mm, so the 260mm bird was truly abnormal. (Or the specimen was misidentified!)  Thus the wing length suggests P. tenuirostris but is not definitive.

 

“TAIL LENGTH:

Unfortunately, the tail length measurements are even more problematical. The length measured for the bird in question is 79 mm.  Again, that is good for a typical P. tenuirostris, versus an average of 81mm for 37 males and 83 mm for 30 females.  But again there seems to be a problem with the measurements given in the paper for their three P. griseus specimens.  Their average tail length was 104 mm, which is a full 10 mm longer than the longest measurement listed in HANZAB!  The range given in HANZAB is 80-94 mm (sample size 187) and the mean is about 88 mm.  Thus the 79 mm measurement of the specimen in question is average for P. tenuirostris and very small for P. griseus, but only 1mm shorter than the smallest measurement in HANZAB.  The only explanations I can suggest for the authors' too-long tail measurements for P. griseus is that over-zealous measuring may have damaged the skins by splitting the skin at the insertion or the proper insertion may have been missed altogether.  As this measurement is usually done largely by feel, with the tail coverts hiding the proper insertion, either error could have happened.  Once again, the tail length is right for P. tenuirostris but may not be definitive, and there are problems with the authors' tail measurements for P. griseus.

 

“TARSUS AND MIDDLE TOE:

At this point in the analysis I thought, "What about Christmas Shearwater?" However, Christmas Shearwater (P. nativitatis) is clearly ruled out by the too-large feet of the specimen in question.  Moreover, in my limited experience with Christmas Shearwater it does not show the white-throated / black-capped appearance shown well in the photographs.  That appearance is typical of Short-tailed Shearwater.  Although the bill and wing measurements could fit P. nativitatis, the 49 mm tarsus and especially the 65 mm middle toe are too long for this species.  The limited samples listed in HANZAB show this species to have a tarsus ranging from 35-45.3 mm and a middle toe ranging from 49.7-51.5mm.  The specimen in question clearly does not fit. Moreover, if ratios of tail to tarsus and tail to middle toe were taken, then the specimen in question would be FAR out of range, as P. nativitatis has a longer tail as well as smaller foot; the HANZAB tail measurements range from 88-94 mm, versus 79 mm measured for the bird in question.

 

“Comparing foot sizes for P. tenuirostris and P. griseus, there is not much difference, but again what difference there is somewhat favors P. tenuirostris.  The 65 mm middle toe falls in the range for both species, with the ranges given as 59.4-66 mm for P. tenuirostris and 60-70mm for P. griseus.  However, the 49 mm tarsus measurement fits the range 49.1-55.9mm for P. tenuirostris but is just slightly too short for the range 50-60.7mm for P. griseus.  Once again, however, the middle toe being at the long end of the ranges while the tarsus is at the short end suggests that one or both of these measurements may have been taken slightly differently than the measurements listed in HANZAB, as in most individuals the tarsus and the middle toe should vary in parallel with larger feet or smaller feet retaining generally similar proportions.  Once again, the authors' measurements of the bird in question favor P. tenuirostris but with lingering questions about the methods of measurement.

 

“WEIGHT:

The weights given for the bird in question are "Peso" = 340 g and "Total" = 370 g.  I don't know Portuguese and so I don't know what the difference in these two weights is.  However, either weight is FAR below the normal weights for either P. griseus or P. tenuirostris but is in line for beach-cast birds with no fat reserves.  This says nothing useful about the species identification.

 

“CONCLUSION:

The measurements support the identification as Short-tailed Shearwater Puffinus tenuirostris.  However, there are nagging questions about the measurements that muddy the confidence of this conclusion.  Nevertheless, I do confidently identify the bird in question as Short-tailed Shearwater Puffinus tenuirostris based on the photographs with the backing of the measurements.  The direct photographic comparison with a reference Sooty Shearwater Puffinus griseus essentially eliminates my concerns about bill measurement errors, and the plumage pattern of the head is typical of Short-tailed Shearwater Puffinus tenuirostris.  Although it would be nice to clarify the questions about the suspect measurements, they mostly relate to the three Sooty Shearwaters rather than the bird in question, and I have no hesitation accepting the authors' identification of it as Short-tailed Shearwater Puffinus tenuirostris.

 

“One last subject relates to the authors' suggestion (from their English abstract) that their bird flew from east to west by following the prevailing winds around the South Pole [sic - Antarctic coast waters].  I am skeptical. For one thing, the easterlies only predominate quite close to the Antarctic continent, considerably farther south than Short-tailed Shearwater normally ventures.  In a huge band just to the north the winds are almost always westerly and much stronger than the easterly winds close to the Antarctic coast.  Moreover, their suggestion relies on the antiquated belief that tubenoses fly where the wind drives them.  More recently it has become obvious that a healthy tubenose flies in whatever direction it chooses, almost regardless of the wind direction and strength.  That is one of the ways that tubenoses show themselves to be the most amazing flyers of all birds (with the special case of the hummingbirds excepted).  The rare exceptions, the truly storm-cast tubenoses, would be affected by extreme storms that would not take one to "northeastern" Brazil.  It is all speculation in any case.  I am not against trying to publish such speculation to attempt to explain a vagrant occurrence, but it must be recognized as speculation.  My own such speculation regarding our recent record of Orinoco Goose on the southern coast of Peru was scornfully excised by a reviewer and the editor of "Cotinga."  These authors' suggestion for why the Short-tailed Shearwater arrived on the "northeast" coast of Brazil has even less merit, in my opinion.  (Also, the authors' statement that Short-tailed Shearwater occurs only rarely off California is incorrect.) But the fact remains that the Short-tailed Shearwater DID get there; that is the essential point.”

 

Comments from Stiles:  YES, especially in view of the fact that another specimen record for the Atlantic exists.  Even though this is a Pacific Ocean bird, it is also one of the world’s most abundant procellariids and its migrations take it through most of the Pacific, so an occasional transoceanic stray is not totally unexpected.”

 

Comments from Nores: “YES, el hecho que haya un ejemplar capturado y que haya sido aceptado por el “Comitź Brasileiro de Registros Ornitológicos” y la revista Ararajuba, son elementos importantes para aceptar el registro. Además, está el comentario de Sullivan.”

 

Comments from Cadena: “YES. I have to go with the experts' opinion here.”