Saturday, October 29, 2011

Snow Tracks of the Striped Skunk (Mephitis mephitis)

To paraphrase Robert Frost:
"Whose tracks are these?
I think I know.
It is the striped skunk,
The odor tells me so."

With the overnight snow a couple of days ago, I awoke to find meandering trails throughout the back yard where some creature had wandered all over the back lawn. The snow was wet and melting, so no distinct footprints could be discerned, but there is still enough evidence to identify the trail-maker.

The meandering route would be typical of a striped skunk (Mephitis mephitis) searching for grubs under the roots of the grass. Additionally, a couple of weeks ago, there was a very strong skunk odor out by the sun porch. It must have sprayed either under the porch or right next to it. The odor was literally strong enough to make a person sick until we aired it out the next morning. This evidence is enough to identify the striped skunk as the largest wild animal identified so far in this blog as a resident of my yard.

It leads me to wonder though: did the skunk run into some other creature living under the deck and use its defensive spray? It seems odd that it would find an occupied spot and then choose to live there. I suspect, however, that the skunk, out looking for a home used its musk to claim the spot. Any other animals in the area would be able to smell the skunk's spray for months, giving them a very good reason not to go near the skunk's winter den. I've never heard of this sort of behavior, but, logically, it makes sense to me. I'll have to do some further research.

I suspect the striped skunk has taken up residence beneath our house. It's odd to see its tracks in the snow, because skunks have usually gone into a winter torpor before snow sticks on the ground, as that doesn't often happen until the ground is frozen at the surface level, but this one is still actively hunting in the early snow. Young skunks often have a tough time surviving their first winter (see the Quick Facts below), so I'll be interested to see if it is still around in the spring.

Skunks can wreak havoc on a well-maintained lawn as they root for grubs. They will wander around the yard, digging little holes sporadically as they locate grubs. They'll also eat insects on the surface as they find them. Earthworms or beetles caught above ground make a nice addition to the skunk's diet. They also hunt larger prey such as mice, moles and frogs. They'll eat bird's eggs and berries and grains, as well. In an urban setting, bird feeders and garbage cans make attractive feeding stations for skunks if they are left within reach. Skunks are small and are generally unable to knock over a medium weight garbage can, but if bags of garbage are left out, they'll happily tear into them.

Skunks hunt at dusk and dawn and may sometimes be seen in the early morning hours as they finish up their feeding and head back to their dens for the day or during the evening hours caught in the headlights as one drives along country roads. Animals that are active at these times are referred to as neither diurnal nor nocturnal, but crepuscular.

Skunks and Rabies:

Skunks are one of the most common vectors of rabies in North America and should always be given a very wide berth for that reason if not for the smell. Skunks that act aggressively toward humans should be reported to state wildlife agencies, especially if there is an active outbreak of rabies in the area.

Skunk Spray

William Wood of Humboldt State University offers a chemical analysis of skunk spray. Thiols, he says, are responsible for the strong odor and can be chemically nullified with hydrogen peroxide or baking soda. Interesting, he notes that a second class of thioacetates found in skunk spray doesn't smell as strongly, but when later mixed with water, they may change into more odoriferous compounds. I would think that this might be useful for marking territory as it would linger and be refreshed whenever it was damp outside, although I still haven't found any information suggesting that skunks use their spray for this purpose.

Quick Facts about The Striped Skunk (Mephitis mephitis):
What do striped skunks eat?
Striped skunks are opportunistic omnivores. They'll eat a wide variety of insects, small mammals, reptiles, fruits and berries, grains and seed, and occasionally carrion.
Where do striped skunks live?
Striped skunks live throughout North America where they are widespread and common throughout Canada, the United States, and northern Mexico. In terms of habitat, skunks are fairly adaptable and have probably benefited from the conversion of so much landscape to short-cut lawns which make excellent foraging grounds for them. They are also found in forests and agricultural lands as well.
Where do  striped skunks go in the winter?
Striped skunks do not migrate. In the winter they don't truly hibernate, but fall into a state of lower metabolism and reduced activity. Food is hard to find once the ground freezes and the skunk's prey holes up for the winter, so skunks compensate by fattening up as winter approaches and then relying on the reduced needs of their lower metabolism to see them through until spring. The state of reduced activity is called a winter torpor and although the skunk will sleep quite a lot during this time, it does have periods of wakefulness unlike a true hibernation.
What is the lifespan of the striped skunk?
Skunks generally live 2-4 years in the wild, up to 15 years in captivity.
Life cycle of:
Skunks do not mate for life, or even for a single year. Males are opportunistic breeders and will mate with any fertile female they find and then move on. Females raise and care for the young for their first summer until they are old enough to find their own food and go their separate ways. Litters range from 4-7 kits says the University of Delaware's Emily Magnani, and typically live from 2-4 years in the wild. Magnani says that as many as 90% of skunks do not survive their first winter.
Notes:
Despite their poor first year survival rate, striped skunks are common and area species of least concern according to the IUCN Red List of Threatened Species. Once widely harvested for their distinctive fur, they have, fortunately for the striped skunk, fallen out of fashion. Skunks fall prey to the usual suspects, coyotes, wolves, bobcats and the like. They'll also fall victim to dogs although once the dog gets a faceful of skunk fury in the form of its defensive spray, the fight usually ends with the dog running home.

I'll try to get some pictures with the trail cam to add to this post, but with bad weather expected and winter approaching, it may take some time.