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Animal Diets

Squirrels Digging For False Truffles

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Such creative and informed answers to yesterday’s Mystery Photo, and many that were right on the mark!  To set the stage, several 2” to 4”-deep holes riddled the ground under a stand of Eastern Hemlocks. Something had obviously been digging for something, but who and what? Close inspection of the holes revealed two things. The animal that had dug the holes had run into some thick hemlock roots, and with a clean 45° angle cut, had snipped them in order to have access to the soil beneath them. Secondly, some of the holes had pea- to marble-size, spherical tan objects that resembled puffballs both lying at the bottom and wedged into the sides of the holes.

Only because I had read Paul Rezendes’s Tracking & the Art of Seeing years ago did I recognize these holes and spherical structures within as the work of an animal looking for false truffles (a genus of fungi) to eat. By putting the various clues together – a hemlock stand, 3” to 6”-wide holes, clean incisor-snipped roots, and a few remnant truffles – the mystery at to what was being sought was solved.

As to who had done the digging, white-tailed deer, squirrels and porcupines all fancy false truffles. Both porcupines and squirrels have incisors that would make a clean cut through the roots. If porcupines had been digging here, there would likely be scat and/or quills lying about, which there were not. Thus, most likely it was a squirrel that had smelled, unearthed and eaten the false truffles.

Rezendes found that the truffles he discovered had dried spores inside them, and assumed that this made them undesirable to the animal that unearthed them and therefore they were not eaten. The spores of the truffles I found were not dried out, so I have no idea why they weren’t eaten, but I’m very glad they weren’t, as their presence allowed me to solve this mystery and see this phenomenon which I’ve been looking for for decades.

It may interest some to know that false truffles and Eastern Hemlocks have a symbiotic relationship. The fungi are attached to hemlock roots, so the minerals and water they absorb are available to the hemlocks. The hemlocks provide the fungi with sugars that they (hemlocks) produce through photosynthesis. Squirrels (and porcupines and white-tailed deer) and eastern hemlocks have a similar mutually beneficial relationship in that hemlocks provide the truffle-eaters with food, and the squirrels, porcupines and white-tailed deer disperse the spores of the truffles they’ve eaten. (Caution: Do not eat false truffles – they are considered toxic to humans.)

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Coyotes and White-tailed Deer

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Coyotes will eat just about anything they come across – rodents, rabbits and hares, beavers, muskrats, birds, even garbage. Whatever is available and whatever they can catch they will consume. Very often you find white-tailed deer hair in their scat (see photo), and while a majority of the time it comes from deer carcasses that they have come across, there are two times of year when they are known to hunt deer. One is in the spring, when fawns are vulnerable, and the other is during the winter, when one of two conditions are present that favor coyotes: when the snow is deep and deer have to struggle to move faster than coyotes, and when there are crusty conditions, when coyotes are held up on top of the crust, but deer break through, often cutting and exhausting themselves.

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White-tailed Deer Winter Diet

1-4-16-fungus-eaten-by-deerimg_0948The diet of White-tailed Deer varies with the seasons, but in general deer require a high-quality diet and tend to choose the most nutritious options available. In addition to mast (fruit, acorns, beechnuts) and browse, herbaceous plants and fungi make up the greatest portion of their food. However, their foraging choices are extensive. White-tailed Deer have been known to consume the washed-up carcasses of alewives after they (the alewives) have spawned as well as insects, mice and the nestlings of ground-nesting songbirds.

Microorganisms inside a deer’s four-chambered stomach enable cellulose in the plant material consumed to be digested. In winter, the microorganisms within the deer stomach are different from the microorganisms in spring, summer, and fall. This change allows deer to digest a diet of woody browse during winter months and turn the high-fiber diet into proteins through intricate physiological processes. Offering food items during this period other than woody browse (such as hay) is detrimental to deer, as it requires different microorganisms in the stomach in order to be digested. Thus, even though a deer’s stomach might be full (of hay, for instance), it may starve due to the inability to digest it.   (Photo: shelf fungus eaten by White-tailed Deer, showing lower jaw incisor grooves)

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White-tailed Deer Diet In Transition

10-25-16-deer-scat-20161017_5319Even if you didn’t know that a white-tailed deer’s diet changes in the fall, their scat would be a dead giveaway. Its texture and formation are excellent indicators of what a deer has been eating. During the summer, individual pellets are often lumped together due to the moisture content of their summer diet (grasses, clover, alfalfa, apples and other herbaceous food). As winter approaches, deer transition to a diet of twigs, leaves and acorns which results in the formation of individual, dry pellets. At this time of year, it is possible to find both forms of deer scat.

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Black Bears Gorging

10-28-16-corn-203Black bears are omnivores as well as opportunists.  They will eat almost anything that they can find, but the majority of their diet consists of grasses, roots, berries, nuts and insects (particularly the larvae).  As the days cool, and the time for hibernation nears, black bears enter a stage called “hyperphagia,” which literally means “excessive eating.”  They forage practically non-stop — up to 20 hours a day, building up fat reserves for hibernation, increasing their body weight up to 100% in some extreme cases.  Their daily food intake goes from 8,000 to 15-20,000 calories. Occasionally their eyes are bigger than their stomachs, and all that they’ve eaten comes back up.  Pictured is the aftermath of a Black Bear’s orgy in a cornfield.

If you  share a bear’s territory, be forewarned that they have excellent memories, especially for food sources.  Be sure not to leave food scraps or pet food outside and either delay feeding birds until bears are hibernating (late December would be safe most years) or take your feeders in at night.

NOTE:  Orders for 2017 Naturally Curious calendars must be received by October 31.

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Beavers Consuming Herbaceous Plants

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One associates Beavers with a fairly strict diet of bark and twigs. While their winter diet consists primarily of woody plants, they consume a variety of herbaceous and aquatic plants (as well as woody) during the spring, summer and fall months. Shrubs and trees make up roughly half the spring and autumn requirements, but as little as 10% of the summer diet when herbaceous plants such as sedges and aquatic plants become available.

Recent observation of a local active Beaver pond revealed that Interrupted Fern (Osmunda claytoniana), Jewelweed/Touch-Me-Not (Impatiens capensis) and grasses are high on the list of preferred foods of one Beaver family during the summer, although woody plants such as poplars (Populus spp.) and Paper Birch (Betula papyrifera) have also been consumed in fairly large quantities.   All too soon Beavers in the Northeast will be limited to the bark of branches they’ve stored under the ice. Until this time, they take advantage of the accessibility of more easily digested herbaceous plants. (Thanks to the Shepards and Demonts for photo op.)

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White-tailed Deer’s Diet Changing With The Season

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Being ruminants, white-tailed deer have a four-chambered stomach which allows them to digest a wide variety of food, including leaves, twigs, fruits and nuts, grass, corn, alfalfa, and even lichens and fungi.  Their stomach hosts a complex set of microbes – organisms such as bacteria, which are too small to be seen with the naked eye – that change as the deer’s diet changes through the seasons.

In general, the green leaves of growing plants are consumed in the spring and summer, while fruits and seeds are eaten as they become available. Hard mast foods, such as hickory nuts and acorns, are an extremely important component of fall and early winter diets when deer need to establish fat reserves. The buds and twigs of woody plants are a mainstay of their diet in winter.

At this time of year it is not unusual to see deer grazing in fields that are just starting to have a touch of green. Grass is a welcome change from their winter woody diet, but it only comprises a very small (less than 8%) of a deer’s overall diet, due to its low crude protein and digestibility. Because their rumen (the stomach chamber where most microbial fermentation takes place) is small relative to their body size, a white-tailed deer’s diet must be high in nutritive value and capable of being rapidly degraded in the rumen.  Therefore, white-tailed deer rely primarily on alfalfa, clover, beans and other legumes, additional herbaceous flowering plants, and browse, all of which have more protein and are more easily digested than grasses.

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