Proposal (255) to South American Classification Committee

Follow-up to Proposal 155: Split Thalassarche cauta into three species

Effect on South American CL: Proposal 155 was accepted to split Thalassarche cauta into at least two species. The question now is two (cauta/steadi) and (eremita/salvini) or three species (cauta/steadi), eremita, and salvini.

Background: The necessary background is in proposal 155, I won't re-hash that here. I don't think that new work on this has been published, but in the intervening time I have seen a photo of a cauta/steadi from Chile (unpublished). All three of these proposed species, cauta, eremita and salvini have been seen and photographed in our region. There are specimens for eremita and salvini at least.

Analysis and Proposal: Based on clear differences in adult plumage and bill coloration, used during breeding displays as well as lack of hybridization during rare sympatry events (see proposal 155) in addition to molecular and other data noted in prop. 155, I think the argument to recognize three species is solid.

English name notes: The entire complex is often known as the "Shy Albatross," I propose we retire that name to denote the entire complex.

White-capped Albatross is the more common name available for cauta/steadi, although it is sometimes used specifically to refer to steadi. Other names that have been used include Tasmanian Shy (cauta), and Auckland Shy (steadi). I think the simplest thing is to call cauta/steadi White-capped, although some would argue that Shy Albatross should remain with these taxa.

The taxon eremita sometimes is known as Chatham Island Albatross, but recently Chatham Albatross has caught on. I prefer this simpler name.

Recommendation:

YES = recognize three species: T. cauta (White-capped Albatross); T. salvini (Salvin's Albatross); and T. eremita (Chatham Albatross).

NO = recognize two species: T. cauta (White-capped Albatross); T. salvini (Salvin's Albatross, with eremita a subspecies).

I recommend a YES vote for this proposal.

Alvaro Jaramillo, January 2007

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Comments from Stiles: "YES, for reasons essentially stated in the previous proposal on these birds. The English names also seem appropriate."

Comments from Zimmer: "YES". I think evidence for at least a 2-way split is very strong, and evidence for the proposed 3-way split is at least good enough that I think the burden of proof should fall on those offering an alternative. I also think that the proposed English names are well-reasoned, and strongly using "White-capped" for cauta/steadi, while reserving "Shy Albatross" for the complex as a whole."

Comments from Nores: "NO. Eremita y salvini son muy similares entre si, especialmente el diseño de cabeza y pico como para separarlas. Además, el análisis de Penhallurick and Wink (2004) los muestra muy cercanos. Acá también vemos la relatividad de los estudios moleculares. Si sólo estuviera el trabajo de Penhallurick y Wink todos diríamos no son diferentes en base a este estudio molecular. Por el contrario, si sólo hubiera sido hecho el trabajo de Abbott y Double diríamos si son especies distintas como lo indica el estudio molecular."

Comments from Robbins: "NO, I was not convinced in proposal #155 that there are three species. To argue that one event where no hybridization occurred is meaningless. As has been unequivocally established for many taxa, the fact that hybridization occurs or does not occur offers little insight into defining species, let alone whether one taxon is sister to another. There is still much to be clarified regarding species limits within albatrosses."

Comments from Pacheco: "YES. Reconheço que, a partir dos dados ora disponíveis, eremita e salvini são consistentemente morfológica e geneticamente distintas e podem ser tratadas como espécies."

Comments from Stotz: "NO. I don't think that occasional individuals of one taxon that don't breed or show evidence of being in breeding condition inside the breeding range of another is sufficient support for reproductive isolation. Given that eremita and salvini are so close genetically (nearly as close as cauta and steadi), I would say that treating them as conspecific still makes sense."

Comments from Remsen: "YES. The differences in coloration between eremita and salvini roughly comparable to those between salvini and cauta. But more importantly, the sympatric breeding, albeit small N, puts the burden of proof on those who would consider salvini and eremita conspecific. Even if only N=1, look at it this way: the chances of two individual eremita mating with each other by chance alone in a population of 150 to 450 salvini pairs on the Snares (breeding population counts from Tickell 2000, App. 15) are 1/150 or 1/450, in other words incredibly small. So, yes, N is small, but those are the data we have to work with. Until better data suggest otherwise, I personally think that there is no choice but to rank them (eremita and salvini) as separate species. For what it's worth, I note that Brooke's (2004) albatross book, an Oxford Univ. Press that is beyond my price range so I do not have access to it, also treats them as separate species."