An online resource based on the award-winning nature guide

Animal Digestion

How Beavers Digest Cellulose

12-26-14 beaver sign 125Some beavers are still managing to find openings in their ponds which give them access to fresh cambium, the soft layer of wood just under the bark of a tree. Cambium contains a lot of cellulose, in addition to starches and sugars. Like all herbivores, beavers do not possess enzymes that are capable of breaking down the large cellulose molecules (cellulases). In their place, beavers employ micro-organisms, such as bacteria, that can break down cellulose.

These bacteria are located in a pouch called a cecum, located at the beginning of the large intestine. (Ruminants such as moose and deer have rumens in place of ceca.) Colonies of these microorganisms in a beaver’s intestines digest up to 30% of the cellulose from the woody material that it eats. Further nutrients are recovered in the form of fecal pellets that the beaver re-ingests.

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Black Bear Scats Reveal Diet

8-25-14  black bear blueberry scat 062Black Bears are eating heavily now, in preparation for the coming winter when they will not eat or drink for several months. Some of what goes in must come out, however, and it can tell you a lot about the diet of an animal. Black bear scats typically weigh ½ to 1 pound or more. They have different shapes and consistencies, depending on what the bear has eaten. Black bear scats may be tubular or loose, depending on the amount of moisture in the food that the bear ate. Scat from succulent vegetation or berries is typically loose. Interestingly, black bear scats do not have an unpleasant smell if the bears ate only fruit, nuts, acorns, or vegetation — they smell like a slightly fermented version of whatever the bear ate.

At this time of year, Blackberries, Wild Sarsaparilla fruit and Blueberries are ripe and favored by bears. You can determine what a bear has been eating by the shape and size of the seeds in its scat. (A bear’s scat can consist of just one type of fruit if there is an ample supply of that fruit.) Wild Sarsaparilla seeds are crescent shaped, Blueberry seeds are tiny and sand-like, and Blackberry seeds are larger than Blueberry seeds. Blueberry scat (pictured) usually includes whole berries that were not soft and ripe enough to be broken up in the bear’s stomach. Bears hardly stop to chew berries. Instead, they swallow them whole and let the muscular, gizzard-like section of their stomach grind the pulp off the seeds. (Thanks to Jeannie Killam for photo op.)

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Moose Scat Form Reflects Diet

1-16-14 moose scatBiologists estimate that moose defecate anywhere from 13 to 21 times a day. The appearance of moose scat, as well as deer, varies throughout the year. Its form depends in large part on the amount of moisture in the moose’s diet. Summer scat often looks like loose plops, or patties, due to heavy consumption of herbaceous aquatic and semi-aquatic vegetation. As fall approaches and a moose’s diet includes more woody vegetation, its scat consists of clumps of soft pellets. In the dead of winter, when moose are browsing almost exclusively on trees, individual dry pellets are produced. Spring scat is similar to fall scat, as moose are transitioning into a different diet during both of these seasons.

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Raccoons Gorging

9-17-13  raccoon vomit, corn 203In New England, Raccoons prepare for winter by eating extra food during the fall. Being omnivores, they eat everything from crayfish and mice to nuts and corn. The latter two items are particularly important, as these high carbohydrate foods allow the Raccoons to put on considerable fat reserves for the cold winter months. According to the Farmer’s Almanac, Raccoons are wasteful when it comes to harvesting corn, because they don’t really like sweet corn all that much. You could fool the Raccoon that deposited this pile on the forest floor adjacent to a Vermont corn field. It gorged on so many ears of corn that it got sick, and there wasn’t a hint of anything but corn kernels that came out of its stomach. (The pile was well over a foot in length.)

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White-tailed Deer Diet & Digestion

11-30-12 deer eating IMG_6035A white-tailed deer’s diet consists of a wide variety of herbaceous and woody plants, the ratio of one to the other being determined by the season. Fungi, fruits and herbaceous plants form much of the summer diet. Dried leaves and grasses, acorns, beechnuts and woody browse are important autumn and early winter food. After snowfall, the winter diet consists mostly of woody browse (twigs, leaves, shoots and buds) from many different trees (maples, birches and cedars among them). Come spring, deer eat buds, twigs and emerging leaves. Deer are ruminants (as are cattle, goats, sheep and moose). They have a four-chambered stomach, which is necessary in order to digest the cellulose in the vegetation they consume. Food goes first to the rumen, the first of the four chambers, which contains bacteria and other microorganisms that help digest the cellulose. Food is circulated from the rumen back to the deer’s mouth by the second chamber, or reticulum, and the deer ruminates (“chews its cud”). The third chamber, or omasum, functions as a pump, sending the food to the final chamber, the abomasum, where the digestion process is completed.