Ferret Evolution: Parts 1, 2, 3, 4a & 4b
Ferret Evolution Part 1
Q: Can you explain how ferrets are adapted for life in the wild?
Actually, ferrets are NOT adapted for life in the wild. They are adapted to help humans hunt rodents and rabbits. There are differences between ferrets and wild polecats that show a human hand and intent towards that adaptation. Because this is such an important subject in legalisation issues (feral fert BS), I'll answer it in three posts. Part one will be the adaptations for survival of polecats that ferrets share, the second will be some of the major differences between the two, and the third will address feral issues.
Ferrets and polecats share many characteristics, most notably the fur colouration. While small differences exist, the sable ferret colouration is very similar to that of the European polecat, and the cinnamon colouration is very similar to that of the steppe polecat. Siamese sables, especially light chocolates, are strikingly similar to the colouration of the black-footed ferret. What this means in layman's terms is, somewhere, someone has a female cinnamon Siamese ferret that is the spitting image of a black-footed ferret. It also means colouration is a poor way to distinguish between ferrets and wild kin.
Almost all the other adaptations shared between the polecat and the ferret are those for a life underground or near the water. Look between the toes of your ferret and you will find a webbing that extends to the third bone of the finger. When the fingers and feet are spread out, the webbing converts the paws to duck-like feet. This is great in swimming, but it is also useful in digging, allowing lots of dirt to be scooped out of holes. It is thought that webbed feet are common to most mustelids, and the common ancestor was adapted to a semi-aquatic life. It is thought that those non-aquatic mustelids (badgers, wolverines) that still have the webbing have kept it for digging. Polecats usually live near small streams or marshy areas, and the webbing is probably more for swimming than for digging, but useful in both.
Both the ferret and the polecat have tiny dark eyes. Most carnivores that exploit the dark have rather large eyes, such as in owls, cats or racoons. The difference is polecats do not typically hunt in dimly-lit areas, but in dead-dark areas. Deep cave dark. So their eyes are small (but dark to absorb as much light as possible). They see in black and white for the most part, although polecats see better in the blues and reds than ferrets, who mostly see reds. The eyes are also slit-like, which is a common adaptation of burrowing animals to help keep their eyes clean from dirt.
Instead of vision, the sense of smell is predominate. Look square on to a ferret's face and you see tiny eyes and a huge nose. Smell is important because no eye can see in dead-dark burrows. A polecat's nose is so sensitive it can smell a baby's fart from down the street, and tell what it ate for lunch. I assume the ferret's nose is similarly sensitive.
The ears are also small and close to the head. Look close at your ferret and you will notice a thick tuft of hair and a flap of skin that, if brushed towards the tail, will cover (or mostly cover) the opening into the ear. This tuft is thicker in most of the polecat skins I've seen, compared to ferrets. The external ears will set flat against the head, out of the way. Not only is this beneficial inside burrows, but also when fighting a large rabbit. Unlike in cats or dogs, the ear cannot rotate nor focus sound; the polecat's best hearing, like in humans, is forward-quite important within burrows.
One of the more popular aspects of a ferret is it is quiet; there are few loud vocalisations/calls, a trait shared with the polecat. Why? Several reasons; sound doesn't travel far within a burrow, so calls would have to have a lot of energy to escape the burrow to be heard. Polecats are also solitary animals, so vocalisations loose importance. Finally, the sense of smell is so predominate, it begins to expand into the communications arena. Polecats/ferrets probably communicate more by smell than by sound.
Short legs are clearly adaptations for a life in burrows, as are long necks and long bodies. The closest non-mustelid animal with the polecat/ferret body shape are the burrowing members of the Viveridae; some mongooses and merkatts are so similar that they were once mistakenly classed together. Short legs allow the animal to run through burrows. The long body gives the animal speed and power, as well as agility. The long neck allows heavy prey to be carried without tripping over it.
Most burrowing animals lose their tails, such as in many ground squirrels moles and gophers. Also with badgers and the like. Not with polecats; they and ferrets have magnificent tails in comparison. The tail probably serves three purposes; it helps to keep the beastie warm, important in animals that cannot curl into a ball. It helps to balance the long neck when running, and it serves as a olfactory billboard for the fert. After pooping, ferrets commonly rub their bottom on the ground to spread their scent. The tail drags through the scent, and when the ferret is later excited/scared and bushy-tailed, the tail is often waved back a forth, wafting the smell around, doubly important in an animal with few calls.
Polecats and ferrets have skeletal adaptations for digging; the third bone in the finger is long and covered by a large strong nail. The elbow is adapted for digging activities. The head is flat and spade-shaped, and combined with a strong neck, is quite useful in the excavation of dirt.
The reason ferrets share so many traits with polecats is because they evolved from them. The ferret evolution was one of domestication, taking place over thousands of years rather than the millions normally required. The domesticated ferret is as different from the European polecat as the wolf is from the dog, and in some areas, even more so. In the next post I will discuss how that evolution created differences between the two species, and in the third post, will explain how those differences make it extremely difficult for ferrets to become feral.