An online resource based on the award-winning nature guide

Animal Feet

An Opossum’s Opposable Thumbs

11-22-16-opossum-hind-foot3-untitled-1Virginia opossums have expanded their range into northern New England, but are still not commonly seen, except, perhaps, lying on roads where they met their demise. There is much to admire about opossums: they are the only North American marsupial, they have more teeth than any other North American land mammal (50) and they possess a prehensile tail and opposable thumbs (both of which are rarities among non-primates).

The recent discovery of a road-killed opossum provided me with an opportunity to examine its feet at close range. An opossum’s front feet have five toes, each bearing a nail. Their hind feet also have five toes, but only four of them have nails. The fifth toe, or “thumb,” lacks a nail and is opposable, allowing opossums to grasp branches and to climb. If you see their tracks, the hind foot is easily discernable from the front due to the fact that the thumb is at a 90-degree angle to the other toes.

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ANIMAL MOUTHS: Second Book in Children’s Series Released

5-12-15 AnimalMouthsSome of you may have seen Animal Eyes, which was the first of a series of children’s books I am writing about animal anatomy. Just as Animal Eyes took a look at the adaptive differences among different animals’ eyes, Animal Mouths describes the wide range of animal mouths. From birds to butterflies, different mouths and mouth parts are illustrated with photographs and their adaptations for different diets are discussed. Carnivores, herbivores and omnivores are included, as well as an educational section at the end of the book which provides children with photographic/textual “mix and match” activities that reinforce information presented in the main text. Available from the publisher (click on cover image to the right), independent bookstores (most will order if it’s not in stock), online and from me (from those of you nearby). This fall the third book of this series, Animal Feet, will be released.


Snowshoe Hare Hind Feet

2-27  snowshoe hare back foot 011It is not hard to see why the individual toe pads in the tracks of a snowshoe hare’s feet are rarely very distinct. There is a 3/4”- thick layer of hair on the bottom of a hare’s 5- to 6-inch-long hind foot. This hair, along with the size of the foot and the ability of the hare to spread its toes to a width of five inches allows the hare to stay on or near the surface of the snow, and, in the right snow conditions, outrun heavier predators.

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Porcupine Feet Designed for Climbing

porcupine foot IMG_2659Porcupines spend a lot of their life climbing on and clinging to trees due to their woody diet. In addition to strong, curved nails that fit into bark crevices, the soles of their feet have a pebbly surface with very little fur. The bumpy texture increases the surface area and the friction when a porcupine’s feet are in contact with a branch, helping the porcupine hold onto the tree trunk and branches. Even so, examination of porcupine skeletons confirms that many have fractures that have healed, indicating that a significant number of porcupines, while their bodies are adapted for climbing, still experience falls during their lifetime. (Photos: porcupine footpad; insert – porcupine footpad in fisher scat)

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Distinguishing Vole from Mouse Tracks

12-29-13 vole-mouse tracksMeadow Voles (Microtus pennsylvanicus) and White-footed Mice (Peromyscus leucopus) are two of our most common species of small rodents, and they both remain active in winter. Their feet are roughly the same size (approximately ¼ ” wide by ½” long), but the tracks they leave differ slightly, due to their differing gaits. White-footed Mice bound, leaving tracks that have a four-print pattern (parallel larger hind feet in front of smaller, parallel front feet) often with a long tail drag mark in between each set of tracks. Meadow Voles have a variety of gaits, the most common being a trot, which leaves an alternate-track trail, with the hind feet directly registering in the tracks of the front feet. Although voles can also leave a tail mark, they do so much less often than mice. Once the depth of the snow is significant, mouse tracks are more common, as voles tend to travel primarily through tunnels they’ve created under the snow.

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Black Bears Still Active

12-27-13  black bear tracks by GinnyFinding Black Bear tracks in late December shouldn’t come as a surprise, but it often does if you’re unaware of the true timing of hibernation. Most of us assume Black Bears are fast asleep by November, but entrance into hibernation is usually considerably later than this. According to Ben Kilham, a New Hampshire bear biologist , pregnant female black bears den first, around the middle of December, followed by unbred females in late December. Males stay active as long as there is a supply of food available and the weather isn’t too severe. Young males remaining active the longest, often into January, in order to put on as much weight as possible in order to compete with older males the following spring. Occasionally when a winter is particularly mild, and it’s a good year for mast crops such as acorns or beechnuts, you hear or see signs of Black Bear through the winter, but this is the exception rather than the rule. (Photo by Ginny Barlow – Black Bear hind foot on left, front foot on right.)

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Canada Lynx “Snowshoes”

12-16-13 lynx & bobcat feet IMG_3811Bobcats and Canada Lynx are in the same genus, and are roughly the same size (averaging 15 to 35 pounds), with Bobcats usually weighing a bit more than Lynx. The size of their feet is vastly different, however, and not proportional to their relative weights. A Lynx has much larger feet and longer legs than a Bobcat. Its range extends further north, which means it must be well equipped to deal with snow much of the year. A Lynx has big, furry paws, and when its feet land the toes spread way out. Both of these adaptations help a Lynx’s feet act like snowshoes, helping it to chase down food in the winter. Much of the time, this food consists of Snowshoe Hares –anywhere from 60 to 90 percent of the diet of Lynx is made up of hares. The soles of Snowshoe Hare feet are also well-furred, particularly in winter, enabling them to run on soft, deep snow without sinking in very far. Because Snowshoe Hares are extremely fast and agile (reaching speeds of 30 mph and jumping 12 feet in a single bound), the feet of any serious predator must also be well adapted to traveling on snow.

Note: Bobcat sightings are much more frequent than Lynx in northern New England (the southern tip of the Lynx’s range) but breeding populations of Lynx have been documented in the last two years in the boreal forests of Maine, New Hampshire and Vermont.

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