North American River Otters are not territorial in the classic sense of marking territorial boundaries. Instead they mark prime resource areas within their territory. Often, the site is near their den or a productive food area. They visit these sites repeatedly to urinate, defecate and roll around on the ground – so much so that the surrounding vegetation is often dead or dying and is referred to as a “brown-out.”
If an otter has been eating fish, its scat is often just a pile of fish scales. However, if it has been dining on crayfish and it is fresh, the scat can be tubular. No matter what form otter scat takes, a tell-tale sign (in addition to fish scales and/or crayfish exoskeletons) is the presence of clear, white or yellow mucus (scat-jellies). It is not always deposited, but occasionally you do find it. The origin of this mucus is not known – most likely it’s from the otter’s intestinal tract or its anal glands. Research shows that the presence of mucous deposits in some otter species indicates reduced prey availability or reproductive state. (Photo: Tubular otter scat is circled in red. Mucus is on right side of photo. Thanks to David Putnam and Natalie Starr for yesterday’s and today’s photo op.)
Reasons why Mystery Photo was not
Black Bear: Scat consists primarily of crayfish remains.
Beaver: Beavers defecate only in water, and individual pellets consist of tiny woody fragments resembling sawdust.
Raccoon: Raccoons have latrines where multiple scat is deposited, similar to otters. However, only otters deposit mucus.
From their nose to the tip of their tail, North American River Otters measure three to four feet long. Their tail makes up anywhere from a third to nearly a half of their length. A River Otter’s tail is very thick at its base, packed with muscles, flexible, and tapers to a point. It is used to steer when an otter is swimming slowly, propel the otter when it is swimming at high speed and to help the otter balance when it stands upright on its hind legs. River Otters, known for their powerful swimming, can reach speeds of six to seven miles per hour with the help of this appendage.
When loping through the snow, River Otters often hold their tails up off the surface of the snow, but not always. Occasionally drag marks can be seen. In the accompanying photograph, an otter had leapt up an incline, and in so doing left an imprint of its impressive tail in the snow.
(Thanks to Alfred Balch for photo op, and Joan Waltermire for her sharp eyes.)
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There is no denying that North American River Otters know how to travel and have fun in winter. Whether on a flat surface such as a frozen pond or river, field, or down slopes, otters take advantage of the snow, bounding then dropping to their belly and sliding, saving precious energy. Most slides are relatively short, around 10 feet long and 6-10 inches wide, though they can be as long as 25 feet long on slippery ice. At the beginning and end of a slide there are tracks (from where they push off with their hind feet, and cease sliding and begin bounding again), creating a dot-dash pattern. Sometimes a downhill slide is used repeatedly and when it is, bobsledders have nothing over otters, as water from the otters’ coats creates an icy and very slippery slide.
For those of you who would like to view an excellent video of an otter sliding, go to https://www.youtube.com/watch?v=iBB0OLOkvIU .
The low water levels in our ponds this fall do have one benefit – visitors leave obvious signs in the exposed muddy banks. It is fairly astounding how much nocturnal and crepuscular wildlife regularly visits these spots and remains undetected by humans under normal conditions.
Between February and April, female North American River Otters give birth to an average of two or three young inside their dens, which tend to be near water, usually in an excavated cavity under tree roots, logs or thickets. Occasionally they have been known to give birth in abandoned beaver and muskrat lodges as well as woodchuck burrows. The mother doesn’t allow her young to exit their den until they are three or four months old, which, for the oldest litters, is in May. At this point, after their waterproof adult coats have grown in, she begins to teach them how to swim (surprisingly, this skill is not innate). The mother continues to be very protective and secretive, hiding and shielding the young (even from their father) until they are about six month old. Thus, glimpses of young otters are not likely to be had until late summer, and only then if you’re lucky. (Photo: adult river otter. Thanks to Heidi Marcotte and Tom Wetmore for photo op.)
One hundred years ago, naturalists were puzzled by the disappearance of otters in the winter. Some people theorized that they must be hibernating, but in fact, otters are active throughout the year — they just aren’t observed as often in the winter as in the summer. Because they inhabit water, where the fish that they eat are found, and often reside in bank dens (above water level), otters can spend most of their winter under cover of ice. However, some do travel over land from open water to open water, upon occasion. In fact, it is not unusual for them to cover several miles in their search for an open stream or a spring. Run and glide, run and glide, often along a frozen river or marsh, but also through the woods, where otter tracks seem so incongruous. Paired foot prints stop and start each slide; this combination is a dead giveaway as to who is making grooves in the snow. Ultimately, if you persevere when following them, you will find that these slides disappear into open water.
North American River Otters have four webbed feet and strong claws that assist them in water as well as on land. There is relatively little hair on the soles of otter feet, and therefore the individual pads are often well defined in good tracking snow. Each foot leaves a five-toed track, with the inside toe on the front feet being somewhat smaller than the others. Otters have four plantar pad glands in the center of each hind foot with which they mark mounds of vegetation they create.