Variations on a Tayra

Subspecies can be a funny thing in the world of animal taxonomy. Millions of litres of ink have been spilt over the years arguing over how one defines a species but a lot less has been invested in discussing the nature of subspecies. For some popular species concepts (such as the most popular iteration of the 'phylogenetic species concept'), one might question whether any concept of subspecies could be applied at all (I could suggest some hypothetical situations but just how applicable or practical they are is a further matter). Essentially, most subspecies concepts distill down to 'a population that is distinct enough to warrant recognition but somehow doesn't quite qualify as a species'. Historically, the rank has tended not to receive a lot of usage among animals outside groups subject to particularly high levels of taxonomic attention—most particularly, vertebrates and butterflies—and many currently recognised animal subspecies were first named in days when taxon descriptions tended to be much briefer and taxonomists were under less pressure to explain their reasoning. Because subspecies tend to be, by their nature, vague and difficult to define, and because evaluating them often requires detailed population analysis within a species, these historical subspecies have a tendency to linger, unchallenged, in taxonomic listings. And with that as background, tayras.

Tayra Eira barbara photographed in Peru, copyright eMammal. Photography location would indicate this individual to be either E. b. madeirensis or E. b. peruana.

The tayra Eira barbara is a large mustelid (a member of the family including weasels, otters and badgers) found in warmer regions of Central and South America, its distribution extending down to about the level of the southern edge of Brazil. They are long-bodied but robust animals, kind of looking like a 'roided-up stoat. They grow to a head-body length of two feet or more (up to about 71 centimetres) with a tail about two-thirds as long again. Adult males tend to be a third as large again as females and more muscular around the fore quarters. Comparisons have often been made between tayras and the martens Martes of the Northern Hemisphere and molecular studies confirm a relationship between these two genera, as well as the wolverines Gulo. Closer fossil relatives are known from North America and it seems likely that the tayra originated on that continent then spread southwards. Ruiz-García et al. (2013) suggested that the degree of genetic divergence between tayras found in South America might indicate the species may have arrived there about eight million years ago, before the formation of the Panamanian land bridge. Tayras are not the only species for which this possibility has been suggested; these early arrivals may have reached South America by island-hopping between earlier-emerging segments of the eventual connection.

Tayras are diurnal omnivores, their known diet ranging from fruits to small animals to honey. In captivity, it seems they will accept pretty much anything offered to them. Tayras are the only animals other than humans that have been recorded caching unripe fruit in order to eat it after it finishes ripening. It is still not certain to what degree tayras are solitary or social; though commonly regarded as solitary, they have been recorded hunting howler monkeys in groups (Shostell & Ruiz-Garcia 2013). Tayras are mostly found in forests; in some areas they may adjust to more open habitats but seemingly only under sufferance (Presley 2000). Though not regarded as 'arboreal' per se, tayras are adept climbers. Their well developed carpal vibrissae ('whiskers' on the wrists) presumably contribute to this ability. Their wide distribution and adaptability mean that tayras are not currently regarded as of conservation concern though habitat degradation has reduced their numbers in some areas.

Tayra from Belize, presumably the light-headed Eira barbara senex, from Wikimedia Commons.

The body and tail of tayras are generally dark brown or black with the head being distinctly lighter in coloration (light brown or grey to yellow). Leucistic and albino individuals are not that uncommon (yellow tayras are apparently particularly common in Guyana). A patch of pale coloration, varying from a spot to a broad triangle, is often (but not always) present on the chest and throat. Recent taxonomic listings (e.g. Presley 2000) have recognised seven subspecies of tayra distinguished by coloration. The Mexican Eira barbara senex has a greyish white head with the light coloration extending to dark yellow shoulders and a dark brown body. Eira barbara inserta, found in southern Honduras and Nicaragua, is a dark subspecies with a dark brown head, black body and no throat patch. The Colombian E. b. sinuensis is darker than E. b. senex with the nape a darker brown than the head; it may or may not possess a throat patch. Eira barbara barbara, found in southern Brazil, eastern Bolivia and Paraguay, is lighter than E. b. sinuensis but darker than E. b. senex and has a yellowish throat patch. The northern Brazilian E. b. madeirensis is a chocolate brown with the head slightly lighter than the body; again, a throat patch may or may not be present. The Peruvian and western Bolivian E. b. peruana is similar to the last subspecies but has darker legs and a black tail. Finally, E. b. poliocephala, which has a distribution centred on the Guianas, is similar to E. b. barbara but with a darker yellow throat patch and yellow shoulder patches that sometimes merge with the throat patch to form a complete collar.

Tayra photographed in a zoo in Panama, copyright Dirk van der Made. Being a zoo individual, its origins are a bit more open than the other individuals shown on this page, but Panama is home to Eira barbara inserta and E. b. sinuensis.

Such is the received wisdom as recorded by Presley (2000) but does it accurately reflect population distributions? Ruiz-García et al. (2013) conducted an analysis of mitochondrial genes from tayras representing the five South American subspecies (i.e. excluding E. b. senex and E. b. inserta). They found that of these five subspecies, only E. b. poliocephala (as represented by specimens from French Guiana) could potentially be differentiated genetically. Samples from the ranges of the other four 'subspecies' were intermingled in analyses, leading Ruiz-García et al. to suggest that they should be merged into a single subspecies E. b. barbara (it may also be worth me mentioning that, when I was looking for images to illustrate this post, I had difficulty finding ones in which the supposed differences between subspecies were recognisable). Of course, that leaves the status of the two Central American subspecies undetermined. It may be of note that they seem to be more distinct in appearance than some of the hitherto-recognised South American subspecies but it remains to be seen just how significant this is.

REFERENCES

Presley, S. J. 2000. Eira barbara. Mammalian Species 636: 1–6.

Ruiz-García, M., N. Lichilín-Ortiz & M. F. Jaramillo. 2013. Molecular phylogenetics of two Neotropical carnivores, Potos flavus (Procyonidae) and Eira barbata (Mustelidae): no clear existence of putative morphological subspecies. In: Ruiz-Garcia, M., & J. M. Shostell (eds) Molecular Population Genetics, Evolutionary Biology and Biological Conservation of Neotropical Carnivores pp. 37–84. Nova Publishers: New York.

Shostell, J. M., & M. Ruiz-Garcia. 2013. An introduction to Neotropical carnivores. In: Ruiz-Garcia, M., & J. M. Shostell (eds) Molecular Population Genetics, Evolutionary Biology and Biological Conservation of Neotropical Carnivores pp. 1–34. Nova Publishers: New York.