Wednesday, February 6, 2013

From the Collection: Mink and a Mystery Mustelid

The American Mink (Neovison vison) is widespread throughout the North American continent, ranging from Florida to Alaska, and is absent only in the deserts of the Southwest and the islands of the Arctic. A member of the weasel family, Mustelidae, the mink is a semiaquatic carnivore, and has long been an important facet of the fur trade. Minks are cunning, intelligent animals, and I have been lucky to see them several times — always near bodies of water, including the Chocolay River.

In August of 2011, a mink was hit along US-41, not far from the Carp River bridge. I watched the body bloat then deflate, and before long, it became a dessicated mummy. Despite laying alongside the highway for a number of weeks, the head was intact, and I removed it from the body, cleaned it up, and was left with a perfect little skull:


As you might have noticed, for their size, minks have extraordinarily large brains! The braincase on this skull makes up more than half of its 2.75" length, and the rest is teeth.


Seen from above, the braincase is also quite wide. I am unsure of the age or sex of this individual, but this skull seems to be of the average size; the sagittal crest is pretty well-developed, and the canines are somewhat worn. There is a strange hole on this skull that seems to either be an old injury or perhaps a deformity:

Many years ago, I was given several skulls, some of them labelled and some not, that were no longer wanted at the museum. This unidentified Mustelid skull was one of them:


It's quite obvious that this animal was very aged when it died. The canines are worn and dull, and some teeth are missing. Very rarely do wild animals live to be so old — it is most likely that this animal was a captive specimen. The skull measures 3" in length; it's both longer and more robust than the mink skull discussed earlier.


The dorsal view of the skull shows a stronger sagittal crest and more furrowing of the bone on the braincase. Generally, though, this skull is very similar to that of the mink. The question is, then, what animal did this skull come from? Was it simply a very old, male mink? For what it's worth, I do not believe it is the skull of a European Polecat (Mustela putorius), or of the domesticated version, the ferret.

Here are a few side-by-side comparisons of the two skulls. The skull of the unidentified mustelid is really quite different in shape from the mink, which makes me think it might be a different species:

click for larger view

click for larger view

If you've got an idea of what animal this mystery skull belongs to, let me know! It's got me stumped. Here is a list of members of the genus Mustela — several of the accounts include skull photographs.

6 comments:

  1. Jorie, could this be in Martes rather than Mustela? Here are two resources that might help:
    http://tinyurl.com/aezlnot

    http://www.esf.edu/efb/lomolino/courses/MammalDiversity/labs/NYS3.pdf

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    1. Thanks for the links!

      This skull is too small to be that of a fisher; in addition, it does not have the "rootlet" characteristic of the upper molar (seen here - http://animaldiversity.ummz.umich.edu/accounts/Martes_pennanti/specimens/collections/contributors/phil_myers/ADW_mammals/specimens/Carnivora/Mustelidae/Martes_pennanti_male/lateral/). In terms of North American martes species, that leaves the marten, and I don't think that's a match, either. Though similar in size, this skull seems a lot stockier than these marten specimens - http://animaldiversity.ummz.umich.edu/accounts/Martes_americana/specimens/.

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  2. http://www.skullsunlimited.com/record_variant.php?id=4176
    See the red text and the first photo re: the hole in your mink skull. I've only seen it in skunks before, but according to ADW some members of Mustelidae can also be hosts. Just a guess.

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    1. Oh, interesting! That could very well be the reason for that hole. Thanks!

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  3. Mustela nigripes? It looks a lot like a Black-footed ferret skull to me, but I'm not super familiar with the genus.

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    1. That was a thought of mine, too. For legalities' sake, I hope that's not the case! There seems to be a fair amount of variation in the size and shape of mink skulls, so there's still a possibility it could be that of a very old, large male mink. Still looking in to this! The mystery continues.

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