Tuesday, April 7, 2009

Small Mammals 101

One of the great things about working at a nature center is access to The Morgue, which most nature centers have. The VIC is not technically a “nature center,” so sadly we don’t have a morgue, but fortunately for us, the folks next door at the Adirondack Ecological Center (SUNY ESF – Huntington Wildlife Forest) have a great collection and we get to access it. So this morning I zipped over and snagged some photos to help illustrate the vole vs mouse vs mole discussion from Monday.



Here we have your typical mouse: Peromyscus spp. The Deer Mouse (P. maniculatus) and the White-footed Mouse (P. leucopus) are very similar to each other and difficult to tell apart. This one was not identified down to species, but looking at that tail, I'm leaning towards deer mouse. To tell the difference, here is the list of things to look for, according to D.A. Saunder’s book Adirondack Mammals:

* The deer mouse’s fur is very soft and luxuriant, which the white-footed mouse’s is not.
* Deer mouse fur tends towards grey on the upper parts, uniform in color or possibly with a faint darker stripe down the middle; white-footed mouse fur tends to be more of a reddish- or orangish-brown, not grey, with a dark strip along the middle of the back from head to tail.
* The deer mouse’s tail is dark above and white below (bicolored), is longer than the combined length of the animal’s head and body, and has a tuft of white hairs at the tip; the white-footed mouse’s tail is shorter than the head and body length, is pale below but not white, and does not have a white, tufted tip.

Note the large ears, as well as large eyes (or, in this case, eye holes). We’ll leave the jumping mice for another day.



Compare with this vole. This is the Meadow Vole (Microtus pennsylvanicus). Voles have large heads, compact bodies, short noses, small ears (“microtus” means small ear), short tail, and smallish eyes.


Here we have a Red-backed Vole (Myodes gapperi); note the color of the fur, compared to the meadow vole. The Adirondack region is also home to the Rock Vole (Microtus chrontorrhinus), and the Woodland Vole (Microtus pinetorum). I don’t have photos of these.

Moving on to moles, this is a specimen of the Hairy-tailed Mole (Parascalops breweri). Things that stand out about moles are the tiny tiny eyes that are covered with fur, no external ear flaps, fur that goes no particular direction (this is a great adaptation for an animal that is scooting around underground all the time – no bad hair days), short legs, and especially the spade-like feet.

The Adirondacks are indeed home to Star-nosed Moles, (Condylura cristata), which are noted for the eleven “tentacles” that sprout from the tip of the nose. These tentacles are believed to detect vibrations or electrical signals of prey under ground or under water. Yes – the star-nosed mole is a very capable swimmer and over 75% of its food comes from an aquatic source. Sadly, I didn’t find a specimen of this creature at the AEC, but if you ever have the chance to see one, it is a must.

Then there are the shrews, which are not rodents. Shrews are in a category all their own: insectivora. The most common shrew is this fellow here – the Short-tailed Shrew (Blarina brevicauda):
Blarina is a hefty shrew (most shrews tend to be fairly small), most noted for its venomous saliva. Yes, Blarina is a deadly predator, which actively hunts other small mammals, even those larger than itself, savagely biting them and “injecting” them with its toxic spit, which is a neurotoxin that shortly paralyzes the food item, enabling this small predator to haul it off without a struggle. According to D.A. Saunders, this shrew’s poison gland contain enough toxin to do in about 200 mice. This is a serious predator.

In the Adirondacks one can also find Water Shrews (Sorex palustris):



Masked Shrews (Sorex cinereus), Smoky Shrews (Sorex fumeus), Long-tailed or Rock Shrews (Sorex dispar), and Pygmy Shrews (Sorex hoyi). I’ll try to get photos of these fellows at a later date and do a blog on shrews. Note that all shrews have the long pointy snouts – a good clue to look for.
So, return another day for Small Mammals 102!!!

17 comments:

  1. This comment has been removed by a blog administrator.

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  2. Catharus - I'm glad the photos are useful! That's the great thing about study skins: they aren't going to run away and you can get really close to them to study details!

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  3. I am in the early stages of figuring out what is lurking in my flowerbeds. I recently saw a light tan, short tail, mouse/vole sized critter come out of a small opening under my cement patio. The coloring is throwing me off...

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  4. Anonymous - sounds like you had a meadow vole - aka meadow mouse, altough technically it is a vole. Color can be so variable with these animals - looking in the drawer of mice and voles (see top photo), one is hit by the variation. Some are more grey, others more red, some blonde, some white, some piebald! The behaviour sounds very vole-like.

    The other possibility up here is the southern bog lemming, or the northern bog lemming (although sightings of this in the Park are rather rare). The SBL is described as having a very short tail (about the size of its hind foot), long shaggy fur that is chestnut to brown above with slightly lighter sides. The head is rlatively large, the eyes small, and the ears barely show at all. It's about 4.5" long.

    Hope this helps.

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  5. I recently came accross your blog and have been reading along. I thought I would leave my first comment. I dont know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.


    Betty

    http://adoptpet.info

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  6. Thank you, Betty! I hope you enjoy your time spent here - and find it educational as well! :)

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  7. Ellen,
    I have been having trouble with determining what type of vole i have. I have a meadow vole but i also have another vole that i was told was also a meadow vole but it lacks the visable ears. My guess is that its a pine vole. It looks like most that ive seen but im having people tell me otherwise. Like the none visable ears, its chestunt brown with a bit of grey and black fur mixed in. Also the underside is a light grey. Any help would be great.

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  8. Anonymous - I consulted with our small mammal expert next door and she had the following to say: the best way to ID voles is by looking at the tail length compared to the length of the hind foot. We have four voles and a lemming here in the Adirondacks: red-backed vole (obvious reddish fur on its back and pretty obvious ears); woodland/pine vole (tail slightly longer than hind foot); rock vole (yellow fur around nose); and the meadow vole (big chunky critter from fields and meadows; tail about length of 1/3 of body). The southern bog lemming is not common (I caught one once), but it is possible; it's tail is the same length as its hind foot.

    Here's the description of the woodland vole (Microtus pinetorum) from D. Andrew Sanders' "Adirondack Mammals": The fur is short, soft and silky, almost mole-like in texture. ... The eyes are small; the ears short and nearly hidden by the fur surrounding them. Characters useful in distinguishing this species from other Adirondack voles include fur color and texture, and tail length. The back and sides are auburn or chestnut; the throat, belly, and feet are gray to buffy gray. The tail is about 25mm long (1 inch), slightly longer than the hind foot. Bog lemmings haver shorter tails and shaggy fur; the other voles have longer tails."

    If you have a photo of the animal in question, that would help immensely; even better would be having the animal in hand. :)

    Hope this helps. Good luck.

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  9. We had possibly a mole it had a very pointy noses and short fury tail,Black in color and very smooth fur,slightly bigger than a mouse.I like to know what it is and why is it in my house.

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  10. Anonymous - I suspect what you had/have is a short-tailed shrew. These are the largest of our shrews (well, maybe the water shrew is larger), and are frequently found indoors. It is probably inside because it found your house a) a warm refuge from winter, and b)possibly a good source of food. Shrews are insectivores and carnivores. The short-tailed shrew has venomous saliva for subduing prey, like mice (it won't hurt you). So, it is probably doing you a service by keeping mice out of the house!

    Moles are much less likely to be in houses, mostly because they are fossorial, meaning they live underground. You can easily ID a mole by looking at its front feet. If they are huge and shovel-like, facing outwards (rather than downwards, like normal feet), then you have a mole.

    Hope this helps.

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  11. I believe the rodent in my shoe today was a mole, then. Hey, can you blame him? It's only 5 degrees Fahrenheit outside. Think I might keep it as a pet for the kids rather than putting it down.

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  12. Anonymous -

    Mmm - I'd strongly discourage keeping a mole as a pet. They have very high metabolisms, and you'd have to have a good stock of insects on hand to feed to it continuously. You could, I suppose, feed it from a colony of mealworms and waxworms, but they might not serve the complete nutritional needs of the animal. Odds are, it will not live long in captivity.

    I'd say enjoy it for a short while (30 minutes or so), then let it go. Moles are not destructive to houses, although they can be tough on lawns.

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  13. the specific epithet for the deer mouse is maniculatus, not maniculata

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  14. Thanks for the correction - sometimes typos get away from me!

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  15. I wish we hadn't thrown away the carcasse now of an animal that lived in my garden, then garage, and for the last year the house. It looked like a very skinny mouse with dark black, shiny hair. But that's based on my sighting it once outside and once in garage. The my husband saw it as it ran from garage through open door into house. SHOOT!!! It ate my tomato plant seedlings, seeds of any kind from seed packets and shreaded paper. The closest pictures I've seen looked more like a shrew. What do you think?
    Rebecca Knight, Peoria, IL

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