Skunks of the World: Striped and Hooded Skunks

Striped skunk

It's probably fair to say that when most people think of "skunks" the first animal to come to mind is a black, cat-sized creature with white stripes down its back and a bushy tail. That certainly seems to have been the case for Charles Bonaparte when he first erected the skunk family in 1845, since that is the animal he named it for. More accurately, the type species of the type genus for the family - in a sense, the defining species against which all other skunks are compared - is the striped skunk (Mephitis mephitis). The fact that it has that doubled ("tautonymous") name suggests that, back in 1795, when they named the genus itself, Geoffroy and Cuvier thought much the same thing.

It's hardly surprising; the striped skunk is the most widespread and common of all the species of skunk and surely the most familiar to most North Americans and hence, indirectly, to most Europeans. (For what it's worth, while all the naturalists named above were French, Bonaparte had at least spent a few years working in the US, and was probably much more familiar with skunks than his predecessors). Indeed, the striped skunk lives across the whole of the contiguous US, save only the Mojave Desert and the Great Basin of southern Nevada. It's also found across most of southern and central Canada, and, being no respecter of the US Immigration Service, also into northern Mexico. 

Since the climates of, say, southern California and Nova Scotia are hardly what you'd call "similar" it should be no surprise to discover that striped skunks are adaptable animals. Almost the only requirement they seem to have is that there should be enough to eat - and they'll eat pretty much anything. They do prefer there to be cover in which to conceal themselves, but rocky terrain will do almost as well as thick underbrush, and agricultural fields of corn are perfectly acceptable to them. They're more likely to hide in gulleys or densely vegetated patches if there are any around, but even that isn't a firm requirement.

Skunks prefer to eat insects, notably grasshoppers, beetles, and caterpillars, but they are omnivorous and so will also eat small vertebrates, the eggs and chicks of ground-nesting birds, fruit, and other plants if they're available.  The fact that they eat pest insects means that their presence can be good for gardens or agricultural land - assuming, of course, that you don't disturb them. 

While skunks are generally solitary, the amount of land each occupies varies depending on the amount of food available within it; a population density of two to five skunks per km² (5-18 per square mile) is typical in most places, but this can be higher in suburban areas where food is relatively abundant (skunks will obviously eat any pet food that has been left out, but they won't turn their nose up at refuse either). The area occupied by a given skunk can be anything from 0.1 to 5 km² (5 to 250 acres), but is not fixed, often expanding during the spring, so that it ends up overlapping with that of its neighbours.

Striped skunks are nocturnal by preference, although this can vary depending on the climate, with them being more inclined to come out during the day during the Canadian winter when the nights are too cold for comfort. During the day, they shelter in a den, which may be an underground burrow, but is more likely to be a hollow fallen log or some other aboveground hiding place. So long as there is some enclosed space beneath then, they are perfectly willing to use human structures, such as farmsteads, for their den, and don't seem terribly bothered if the building has yet to be abandoned or is still in use.

Underground burrows are more favoured in the north, and during winter, and each skunk will have several options that it regularly switches between to avoid becoming too predictable to any larger predators. During the winter, pairs of female skunks sometimes share the same den, cuddling together for warmth, but this much less common in the southern US and Mexico, and the males aren't willing to put with cohabitation at all. In addition to this, in the northern parts of their range, skunks are capable of entering torpor during winter, a condition that's somewhere between deep sleep and true hibernation but that only lasts around five hours each day - which is still enough to preserve energy during times of restricted food.

For obvious reasons, skunks have less to fear from predators than most other mammals of a similar size, but even so, puma/cougar/mountain lions, bobcats, and foxes will sometimes prey on them, while eagles and large owls seem little deterred by their spray, possibly because birds tend to have a lousy sense of smell. (Having said which, skunks have a good aim, and a stream of skunk spray straight in the eyes is going to deter almost anything). Given the chance, however, skunks would much rather run away than use their spray, and if they have to, they generally give a warning first, raising their tail and stomping on the ground before letting rip. Youngsters, however, are more likely to give shorter warnings, or none at all, possibly because they aren't as mobile as adults and less willing to take the risk.

The distinctive colours of a skunk are also a part of the warning, a phenomenon called aposematism, where the animal deliberately makes itself obvious in the hope that predators think twice; the same thing can be seen in wasps, coral snakes, and poison dart frogs, among others. The typical pattern for a striped skunk is a black body with a sharply offset white V-shape along the back and a narrow white stripe on the forehead that reaches almost to the snout. But there is more variation than one might think, with some skunks being almost entirely black, or mostly white, and some even having a brown background colour.

Hooded skunk

Striped skunks breed in the early spring, with males mating with as many females as possible, even if one or the other partner is not yet fully fertile. As in cats, the mating act directly induces ovulation, which occurs a few days later. Litters typically consist of five to seven young, although the female usually has a dozen teats, so that litters of up to this size still have a chance at survival. The young are born around April to May, and are initially blind and helpless. They begin to grow hair after a couple of days, but even before this, the stripes are visible on the skin as variations in colour. They can spray within a few days of birth, even though their eyes do not open for up to four weeks.

The closest relative of the striped skunk is the hooded skunk (Mephitis macroura). This is most common in Mexico, where it inhabits much of the country excluding Baja California and the Yucatan. Its range overlaps with that of the striped skunk in the north, although the two seem to avoid one another. It is found in the border regions of New Mexico and as far north as central Arizona, but seems to have recently died out north of the Rio Grande in Texas. In the south, it stretches well beyond the Mexican border into Central America, reaching at least Nicaragua, and probably northern Costa Rica.

Physically, it looks much like the striped skunk and it has the same narrow white stripe on the face. However, it lacks the V-shape on the back, with some individuals having a broad white stripe down the back, others having a narrower one on each flank, and some having both. Other than this, the main distinguishing features from the striped skunk are that the hooded species has a mane-like "hood" of long hair on the back of the head, larger ears, and a longer tail.

In most respects, the two species are otherwise very similar. The hooded skunk clearly has more of a preference for warm climates, and it may also be happier in forests than the striped species - although the latter does inhabit them to some extent, anyway. In recent decades, they have become more urbanised, too, being more likely to be found in built-up areas where humans are abundant, although that might just be due to differences between the character of US and Mexican urban areas that make the latter more attractive to the animals.

Hooded skunks make dens in all manner of rock crevices, ruined buildings, and dense greenery in addition to sometimes digging their own burrows. Given the warmer weather, it's unsurprising to note that they have no need of torpor or to share their burrows in winter. Their spraying behaviour is essentially the same, however, and the stench is created by mostly - but not exactly - the same set of  chemicals. We know almost nothing about their breeding habits, although the fact that females have only ten teats suggests a smaller maximum litter size.

The hooded skunk was first recognised as a distinct species in 1832, long after Johann von Schreber named the striped skunk in 1776. However, despite the fact that it is now the taxonomic cornerstone of the family, the latter was only the second species of skunk to be scientifically described, with another dating back to the very origins of modern taxonomy in 1758. It is to that species, and its closest relatives, that I will turn next time.

[Photos by Tom Friedel and Dimitrij Rodionov, from Wikimedia Commons.]