The recent report of another coyote washing up on the Vineyard’s north shore prompts a few observations on the prospects of the coyote establishing a population here, and the implications for the Island.

Having arrived on the Cape around 1985, coyotes quickly made the crossing to the Elizabeth Islands. By 1986 they were killing significant numbers of sheep and deer there. For the past decade or so there have been reports of live coyote sightings on the Vineyard, but it remains certain that there is no established breeding population here.

Not yet. Once established, coyotes — curious, daring and hungry — make their presence quite apparent. I’ll return to that in a moment.

First let’s look at the issue of crossing what we refer to on our little sloop as the educator, i.e. Vineyard Sound. As everyone who plies the Sound knows all too well, it never fails to teach the boater something new with every sail.

Like all members of the dog family canidae, coyotes are highly intelligent, learn quickly and adapt rapidly to new environments and challenges. But when they set out from the Elizabeth Islands for the Vineyard north shore they are embarking on a perilous adventure, as any human who has attempted the swim will quickly tell you. In spite of excellent vision, because of the great distance involved, there is no way a coyote can appreciate the challenge it faces. Nor do they understand the dangers of hypothermia. Going down the Elizabeth chain from Woods Hole to Cuttyhunk with passages a few hundred yards wide was no challenge at all compared to crossing the Sound.

Let’s assume a coyote, intent on making the crossing, was fortunate enough to pick the closest point between Naushon and the Vineyard. This would be from Nonameset to West Chop, and is approximately two and a half miles if I’ve calculated it right. Then there are tides and winds to take into account. First the tides, which at times and places approach four knots. Let’s assume a coyote swims at the same speed as a dog its size, say one knot (1.15 nautical miles per hour). So our healthy, adult male weighing 45 pounds sets off on his adventure. It is unlikely he would swim in a straight line to begin with, but given the tide, regardless of whether it is on the ebb or flood or both, he is bound to have an erratic passage, with a travel distance two or three times as long as the straight-line distance of two and a half miles, because of the set of the tide at right angles to his desired course.

Let’s say he must travel five miles, at one mph. That is a journey of about five hours. That’s before factoring in the effect of winds, which especially when blowing against the tide, can result in a short, steep chop that is hardly conducive to a pleasant swim. Let’s say the water temperature is a nice summery 65 to 70 degrees Fahrenheit, still a good 30 degrees below his normal body temperature. When the first Vineyard sightings of the coyote occurred, I asked two respected veterinarians whether a dog with a size and coat similar to a coyote’s could swim in 68 to 70-degree water for five hours without succumbing to hypothermia. The answers were emphatically no. A major reason for this is that a coyote, like a collie, has long, loose guard hairs and soft downy under hair, in contrast to, say, a Chesapeake Bay or Labrador retriever, which have short, compact, water-resistant coats. The coat of the coyote, while waterproof in the heaviest of rains on land, simply can’t keep water from penetrating to the under fur when the animal is immersed in water for extended periods of time. This is especially true regarding the underbody, which as any dog owner knows, has much shorter hair than the rest of the body, and is closest to the vital organs. The coat gradually soaks up water like a sponge, in direct contact with the skin, causing massive heat loss, which is hypothermia.

The amount of body fat beneath the skin is a critical factor in insulating any warm-blooded animal, including humans. A Labrador or Chesapeake, with short, tight guard hairs and under fur pressed close to the skin, trapping millions of air pockets against the body, would be far better adapted for long, cold-water swims without ill effects. Incidentally, deer commonly swim between the islands at any time of the year without danger of hypothermia. The reason is that while they have virtually no body fat and no under fur, they have the marvelous feature of hollow guard hairs, providing superb insulation on both land and water. Maine lobstermen commonly happen upon deer making crossings in their infamously frigid waters.

The adult male coyote in prime condition found on Lambert’s Cove in December was exposed to temperatures 15 degrees or more lower than the individual in my hypothetical scenario, making him far more vulnerable to hypothermia than would be the case with a summer passage. Bottom line: can coyotes make it alive from the Elizabeths to the Vineyard? Miraculously, apparently so, but wouldn’t it be interesting to have a video of the entire journey? Or to have monitors on the body recording the body temperature? The question is when will a pregnant female successfully arrive, or more likely, an adult male and female. And could the initial population sustain itself with such a limited gene pool?

The good news is that from the experience on the Elizabeth Islands we know that the deer population there has been greatly reduced, and along with it the incidence of Lyme disease, thanks to the coyote. The bad news is that we know from experience in other parts of the coyote’s range that they will have an impact on ground-nesting birds such as piping plovers, terns and oystercatchers, not to mention domestic animals such as sheep, goats and poultry.

One thing we know for certain, the coyote is a supremely adaptable animal, and it will ultimately likely succeed in its mission, against monumental odds.

Bob Woodruff is a wildlife biologist living in West Tisbury.