Proposal (721) to South American Classification Committee



Treat Pincoya Storm-Petrel (Oceanites pincoyae) as a valid new species


Background. The genus Oceanites currently consists of two very similar species, the Wilson’s Storm Petrel (O. oceanicus) and the Elliot’s or White-vented Storm-Petrel (O. gracilis). Both are small, long legged storm-petrels with a dark body plumage, white rump, and slightly paler upper wing ulnar patches. The taxonomy of this genus has not been controversial, and species status of these two species has not been challenged. Essentially, O. gracilis is a warmer-water species, breeding farther north, slightly smaller than oceanicus, and differs from oceanicus in having a white belly patch. Both are polytypic, and truth be told, there is some complexity here that needs to be addressed by further work, mainly that the ecologically very different South American breeding form of oceanicus, known as chilensis (Palma et al. 2012), might warrant species status.


New Information. Given the stable and uncontroversial nature of this genus, it was with some surprise then that Harrison et al. (2013) described a new and quite striking member of the genus Oceanites, which they named Oceanites pincoyae (Pincoya Storm-Petrel).


         In 2009 various people began to realize that “Wilson’s” storm-petrels seen in the area of Chiloe, Chile were distinctly different from expected chilensis. Part of this was due to images captured with digital photography and an increase in observations in the area. Peter Harrison noted something odd in the area as back as the early 80s, but it needed some context before the importance of that observation was realized. Two specimens from the same general latitude but on the Argentine side of the Andes existed previous to 2009, and had been identified as O. gracilis (at the time the only records for Argentina, and quite far south of the distribution of that species). Doubt was introduced as to whether that is what these unusual specimens really were (Pearman 2000). In 2011 Harrison and a team went to try and observe the bird and capture some for study. A total of 14 birds was captured, measured, and photographed; one was kept as a specimen. The new species was described from the results of that expedition.


         Pincoya Storm-Petrel is a typical Oceanites in general shape, being largely dark with a rectangular rump patch, long tarsi, and yellow webs to the feet. It shares the white belly of gracilis, although the placement of the belly patch is farther back on pincoyae. Otherwise it is the most striking member of the genus. It shows a bold whitish ulnar patch, as well as bright and white underwing stripe. The tail is more extensively white based, with white extending to the outer edge of the outer rectrix. The striking underwing pattern resembles that of the genus Fregetta. Juvenile pincoyae are distinctive, with brighter white ulnar bars, a gray-washed plumage color, and pale loral spot giving them a unique appearance. They are separable at sea from adults given a good view, unlike juveniles of other Oceanites.


         The Pincoya Storm-Petrel is similar in size to O. oceanicus chilensis; it is larger than O. g. gracilis and similar in size to O. g. galapagoensis. Wing and tail lengths differed significantly between O. o. chilensis, O. pincoyae, and O. g. gracilis. A multivariate analysis of morphology found pincoyae to be most similar to chilensis, but with a relatively shorter tarsus and wing, as well as longer toes.


         Field observations of molt in pincoyae suggest they begin molt immediately after breeding, while the young are in the fledging stage. This is unknown in other Oceanites. It suggests that pincoyae is a non-migratory resident in the area. The form chilensis is migratory; although they remain within the Humboldt Current region during the non-breeding season, they do not move north of the equator. Antarctic breeding Wilson’s Storm-Petrels (nominate and exasperatus) are long-distance migrants and spend the non-breeding season in the Northern Hemisphere.


         Ecologically pincoyae is an Oceanites of colder water. This distinguishes it from the warm water associated O. gracilis, a species it resembles due to the white underpart coloration. The South American breeding chilensis is also a cold-water species, but ecologically it is an offshore-foraging species. From the known distribution, it seems that pincoyae is an inshore storm-petrel; in fact it is a bird of sounds and fjords rather than open ocean. It may be unique in being a storm petrel that during its entire life cycle is found within sight of land. Field observations show that it forages differently on average than chilensis. Pincoyae often dives underwater to retrieve food, unusual in Oceanites. Also it performs a distinctive running on the water with closed wings, the “mouse run” that is at the best a very rare foraging technique in chilensis, and perhaps not yet observed in that form. Ecologically pincoyae differs from chilensis and O. gracilis not only in its foraging technique but also in habitat selection (Harrison 2013).


         Preliminary mtDNA work suggests that pincoyae may be more closely related to gracilis rather than to oceanicus. These data also suggest that Antarctic Wilson’s and chilensis are well differentiated. But these data require more work, are tantalizing, and are not near completion for publication (Harrison and Salaberry unpublished data).



         Most storm-petrels being proposed as species splits, are cryptic taxa. Sometimes there is essentially no difference morphologically or at least they are essentially inseparable in the field. This includes recent work on Band-rumped Storm-Petrels (Oceanodroma castro), in which multiple species may be involved, some breeding on the same islands, but at different times of year (Bolton et al. 2008, Smith et al. 2007). Similarly, Leach’s Storm-Petrel (Oceanodroma leucorrhoa) likely consists of multiple species, with both individual variation and seasonal breeding timing differences complicating the understanding of this complex (Ainley 1980). Field identification is problematic to say the least in this group (Howell et al. 2009).  New work suggests that Fregetta also holds cryptic species. Quite opposite to this situation is pincoyae, which differs visibly from its relatives, in both adult and juvenile plumage. Furthermore, it is the most striking species in the genus! Thus, Oceanites pincoyae is not a cryptic species. It went undescribed due to few specimens from or observers in the very limited distribution where it is found.


Sympatry with chilensisNo colonies of chilensis are known north of 50ŻS. However, recently fledged young are found inland in central Chile (latitude of Santiago at 33ŻS) annually, and the species is common on pelagics throughout the breeding season in central Chile (eBird data, pers. obs.). So, it appears that chilensis is found north and south of the presumed breeding distribution of pincoyae (no nests are known yet for pincoyae), and thus they might be sympatric.  If truly parapatric, that would be an unusual situation, with the breeding distribution of chilensis interrupted by that of pincoyae.


Biological Species – Although we don’t know exactly where it breeds yet, although clearly in the latitude of Chiloe Island where they have been recorded throughout the year, we do know that the maritime distribution of pincoyae is bordered to the north and south by chilensis (see above). However, the well differentiated plumage is important. Furthermore, slight but significant differences in morphology are evident. This in addition to unique foraging, and ecology of pincoyae strongly suggests that this is a separate and distinctive species of Oceanites.



         I suggest a Yes vote to accept Oceanites pincoyae as a new species of storm-petrel currently known from the environs of Chiloe, Chile, with vagrant records in nearby Argentina.


Literature Cited

Ainley, D. G. 1980. Geographic Variation in Leach's Storm-Petrel. Auk 97 (4): 837-853

Bolton, M., A. L. Smith, E. Gómez-Díaz, V. L. Friesen, R. Medeiros, J. Bried, J. L. Roscales, and R. W. Furness. 2008. Monteiro’s Storm-Petrel Oceanodroma monteiroi: A new species from the Azores. Ibis 150:717–727.

Harrison, P., M. Sallaberry, C. P. Gaskin, K. A. Baird, A. Jaramillo, S. M. Metz, M. Pearman, M.  O'Keeffe, J. Dowdall, S. Enright, K. Fahy, J. Gilligan and G. Lillie 2013.  A new storm petrel species from Chile. Auk 130: 180- 191

Howell, S. N. G., T. McGrath, W. T. Hunefeld, and J. S. Feenstra. 2009. Occurrence and identification of the Leach’s Storm-Petrel (Oceanodroma leucorhoa) complex off southern California. North American Birds 63:540–549.

Palma, R. L., A. J. D. Tennyson, C. P. Gaskin, and A. Jaramillo. 2012.  The scientific name, author, and date for the “Fuegian storm-petrel”, a subspecies of Oceanites oceanicus from southern South America.  Notornis 59: 74-78

Pearman, M. 2000. Primeros registros del PaiĖo de Elliot (Oceanites gracilis) en la Argentina. Hornero 15:141–143.

Smith AL, Monteiro L, Hasegawa O, Friesen VL. (2007). Global phylogeography of the Band-rumped Storm-Petrel (Oceanodroma castro; Procellariiformes: Hydrobatidae). Mol. Phylogenet. Evol. 43: 755-773.



Alvaro Jaramillo, May 2016




Comments from Stiles: “YES.  O. pincoyae is clearly distinct in plumage and has a unique inshore distribution (and probably quite different breeding biology) from gracilis; I suspect its distribution does not really interrupt the at-sea distribution of gracilis, which probably curves around outside (more west of) that of pincoyae.


Comments from Areta: “YES. Many lines of evidence support recognition of Oceanites pincoyae. I still find it extremely interesting that the first specimens were collected by Andor Kovacs in El Bolsón, Argentina, where low passes allow birds to traverse the Andes relatively easily. As a side note, Andor's family, Kovacs et al. (2005), provided illustrations of their specimens.


Kovacs, C. J., O. Kovacs, Z. Kovacs & C.M. Kovacs. 2005. Manual Ilustrado de las Aves de la Patagonia, Antártida Argentina e Islas del Atlántico Sur. Museo Ornitológico Patagónico. El Bolsón, Río Negro, Argentina.”


Comments from Claramunt: “YES. Very distinctive new species. I have no doubt about its species status.”


Comments from Remsen: “NO.  Based on doubts raised by Howell & Schmitt (2016), I think these need to be addressed before we can accept this as a valid species-level taxon.  With only a single specimen, I think that Howell and Schmitt’s points concerning whether pincoyae represents a morph or extreme end of individual variation, given what photographs from the field show, need to be taken seriously and that further research is required.”


Howell, S. N. G., & F. Schmitt.  2016.  Pincoya Storm Petrel: comments on identification and plumage variation.  Dutch Birding 38: 384-388.


Comments from Robbins: “Although Howell & Schmitt do not explicitly state that they doubt the validity of pincoyae their observations raise enough questions about plumage variation, molt timing, foraging, etc. to leave one wondering if pincoyae is a valid taxon.  Apparently genetic data are unpublished, so I would suggest that we wait for those data before accepting pincoyae as a species.  At least that is my take and so for now I'm going to change my vote from yes to NO.”


Comments from Jaramillo: “It certainly is intriguing, but one needs to also have an open mind as to how many different populations are being seen here in these photos, and exactly how is the variability parsing out? We do not know. One could very well also setup a series of photos to ask the question, where does Fuegian Storm-Petrel end and where does Elliot's Storm-Petrel start? Figures 1.1 and 1.2 are "presumably" Fuegian Storm Petrels, or are they very dark Elliot's? Because they are taken in Valparaiso in colder water we call them pale-bellied Fuegian. However, many birds from the intervening area between classic Fuegian and Elliot's have variable amounts of pale on the belly.  Specimens south of Antofagasta and north of Valparaiso taken on land, so presumably have variable white on the belly. Is it clinal?  Is it variability?  Are the right breeding populations being sampled here, or are we seeing a mix of populations and confusing the issue?  These questions apply to the Elliot's vs. Fuegian, as well as Fuegian vs. Pincoyae.  But I think that if we consider Elliot's a separate species, then pincoyae should be considered a separate species until some other data come out to refute this based on breeding information and or genetics, something we can have a greater grasp on. Storm-Petrels show patterns that include morphs, individual variation, as well as strongly diverged species that look exactly like their relatives, with minor or almost no visual differences. So we are in tough territory!


“We still do not know where these birds breed but there are a few things to consider.


1) April - May, there are annually inland records of Fuegian type birds from the Santiago area. We presume these breed there, and they are in the Andes. Several have been of juveniles, these birds have been showing up for years some were originally published as possible storm driven incidents. But most are not associated with storms, they include juveniles, and the records tend to be from foothill areas at the base of the Andes. They show up consistently up there, and are almost certainly breeding in the Andes, as far south as the Maule area. Examples:


North of Santiago, the Pelambres mine has had birds show up on consecutive years 2011, and 12, including juveniles.


2) We don't know where most Fuegian breed, although colonies are known for this form, but it seems clear that most are in the islands from perhaps the Guaitecas south to Cape Horn, then there are populations on the Argentine side, and Falklands. All evidence is that classic Fuegian is an island breeder.


3) We don't know where Pincoya breeds, but given the argentine records and lack of any evidence of breeding on islets in the Seno de Relocavi, it is possible that they breed up in the mountains. Time will tell.


4) Most Elliot's (non-Galapagos populations) appear to breed in the desert -- lots of evidence found thus far except the active nests.


“In any case, even without nesting cavities confirmed, it is clear that Fuegian type birds are breeding north of pincoyae, likely in the mountains in a region that stretches somewhat north and south of Santiago. We also have classic Fuegian south of pincoyae breeding in the islands. An open question is if the northern Fuegian really are that taxon but that is a separate question and once the nesting areas are found that will come up, they are on a different breeding timing than birds from the south. To me the pattern of this very distinctive form (pincoyae) being sandwiched between Fuegian to the north and south is unusual to say the least. The variation seen strikes me as variation in two different forms that clouds field identification and certainly could involve some level of hybridization, but that question cannot be addressed until the breeding grounds are found, and genetic work is done. For now, we only have the marks we use to visually identify the birds. If we are going to use morphology captured in the field to try to assess the likelihood of intermediates being hybrids or part of a cline, then we really need to have samples that are categorized and scored, so we see how relatively abundant intermediates are relative to the classic Fuegian and pincoyae. Why are there times when essentially all are pincoyae, with nearly no dark-bellied birds in this region? We know Fuegian Storm Petrels are variable, based on photos from Valparaiso, birds caught in the north etc. unless these are clinal with Elliot’s?? It may be that pincoyae is also variable, and perhaps that is expected in this group. Even Elliot's itself, in the north are variable in the extent of white on the belly. But variability does not explain why we have this distinctive form, which is sandwiched with Fuegian type birds to its north and south. I also believe, although I admit it is a gut feel, that Pincoya is breeding in the Andes, not the islands, and this would explain a lot about why it exists. I cannot be sure that there is no overlap in look, or even some amount of hybridization, but at this point it is all too premature. Throwing out the baby with the bathwater is what I fear could happen, given Mark's changing of his vote. I think that Steve and Fabrice have brought up some interesting stuff here, but also I think that their data needs a more rigorous assessment and scoring, as well as rigorous review to understand how relatively abundant classic vs. intermediate types are as well as greater sampling in various areas of Chile. I understand that it is data gathered during tours, and they did well to get this, so it was impossible to do more with it. It does show there is variation in appearance, but how common is it relative to the classic birds? Where is it? How does it relate to variability known in Fuegian? All are open questions.


“NACC just separated the Leach's Storm Petrel complex in the Baja/Alta California region into three species based on a great set of much more complete data than we have now in the southern Cone. But if we had done the taxonomy based on variability of morphology based on a salon of great photos taken in the field, then where would we have gotten? The reality is that there is this rather unique type of storm-petrel, pincoyae, with a very small range, in a sea of darker-bellied forms to the north and the south. It is perhaps the most striking looking Oceanites that exists, it may be variable, and perhaps there could be some hanky panky going on that we do not yet understand, but demoting it to a morph or variation, while we retain Elliot's, which is also clouded by variation in Fuegian ... well given what we know that does not make sense to me


“The idea of waiting for more data to come, which may take years to procure, is also unsatisfying. This is why we have a committee that can react on data and new information. I see no problem with acceptance of a species or a lump based on available data, and flipping on that in the future when better information comes out. But waiting for more data that are not imminent is not a good choice. The hope is to get genetic work done on these birds in a rigorous fashion, but it is going to be tough to get that done in a short amount of time when it is being done by a team which is largely self funded.”


Additional comments from Stiles: “Given all the uncertainty, I also will change my vote to NO.  While I do strongly suspect that pincoyae will be found to be valid, I agree that what we need is a bigger sample of specimens. The genetic data in particular should be revealing, as well as a good sample of plumage variation.”