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Scat

Forest Floor Mystery: Pellets? Old Scat? Cache?

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Lying at the base of a large Eastern Hemlock I recently found two piles of bleached bones.  One pile consisted of mostly vertebrae; the other pile had numerous tibias, humeri and ribs.  All were the appropriate size and shape to have come from several Eastern Chipmunk skeletons – at least four or five.   How did they end up in two distinct piles?

The lack of any fur indicated that regardless of how these bones came to be here, they were deposited quite a while ago.  The lack of any partial skulls or jaw bones and the large number of bones in each pile led me to believe that these were not the remains of two pellets that had been regurgitated by resident Barred Owls. No wild owl pellet I’ve ever dissected, including the large pellets cast by Snowy and Great Gray Owls, has contained even half this many bones, and most contained at least part of a jaw bone.

If not pellets, then scat?  How likely is it that a predator could catch and consume multiple chipmunks rapidly enough so that they would end up in the same pile of scat?  One feasible explanation could be that a fox, coyote or fisher preyed on young, inexperienced chipmunks, but the bones were adult-size bones.

Perhaps these two piles are the remains of a predator’s cache – perhaps a bobcat?

The possibilities are endless as to how this chipmunk graveyard came to be.  However, none of the theories proposed here can explain the dissimilarity between the types of bones in each pile.  If any naturally curious readers have insight into this phenomenon, your thoughts are welcome!

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Ruffed Grouse Unable To Seek Refuge in Snow Caves

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Unlike much of the Northeast, central Vermont has only a few inches of snow on the ground. These conditions can affect all forms of predators and prey both negatively and positively, from exposed mice and voles to easily-satiated hawks and owls. In the case of Ruffed Grouse, which seek shelter on cold winter nights by diving into the snow, less than 10 inches of snow can spell disaster. In their snow caves they are hidden from view and well insulated (where it rarely drops below 20°F.).  A lack of snow can be life-threatening for grouse if the temperature drops too low for too long. Unable to create a sheltered cavity in the snow,  Ruffed Grouse bed down on top of it, often close to the base of a tree where there may be some shelter from the wind. Fortunately, most nights have not been extremely cold thus far this winter.

After the grouse departs in the morning, you often find scat where it bedded down. Grouse scat comes in two forms, one a dry, fibrous cylindrical pellet with a white-wash of uric acid at one end, and the other a softer, darker brown plop. The vast majority of a grouse’s diet (buds, twigs, leaves, catkins) goes directly through its digestive system and forms the dry, courser scat. Finer (and more nutritious) material such as the cambium layer of woody plants enters the caeca, two specialized pouches, before passing through the large intestine. The caeca contain bacteria which break down cellulose and produce the more digested, and therefore more liquefied, scat (see foreground in photo).

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Moose in Winter

1-26-16  moose scat IMG_6307Moose are in their element during northern New England winters. Their bodies are built for snowy, cold conditions. Moose lose relatively little heat due to their large body which gives them a low surface area-to-volume ratio. Long legs enable them to travel through deep snow. However, when the snow gets to be more than 28 inches deep, the energy expended to find food is not worth it. Under deep snow or crust conditions, moose often seek shelter in stands of conifers where the snow is not as deep and where browse is available.

Conifers are beneficial to moose in yet another way. Moose are able to withstand very cold temperatures –in fact, they become uncomfortable (and have been known to pant) when winter temperatures are higher than 23°F. Their coat consists of long, hollow outer hairs and a dense soft undercoat. Our winter temperatures can be quite variable and moose depend on the shade of coniferous cover to keep them cool during our warmer winter days.

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Porcupines Staying Warm Inside & Outside of Dens

If you’ve ever set eyes on a porcupine den, be it in a hollow tree or rocky ledge, you know that protection from the elements, especially cold temperatures, appears limited. While there is slightly better thermal protection in a rock den as opposed to a hollow tree, neither has any insulation, other than the ever-accumulating bed of scat on the floor of the den, and the entrance is wide open. Even so, porcupines save an average of 16% of their metabolic energy by occupying their dens instead of open terrain, due primarily to the shelter from wind that it provides. In addition, porcupines have two layers of fur which insulate them so efficiently that the outside of their bodies are approximately the same temperature as their surroundings, minimizing heat loss.

Porcupines do venture out of their dens and spend between seven and twelve hours a day outside, without the protection of wooden or rock walls. How can they survive this environment? When outside the den (usually when feeding at night), they are often in conifer stands, and a coniferous habitat provides the same energy savings as a den. Eastern hemlock, which is a preferred winter food, has needles layered so thickly that porcupines don’t lose a great deal of heat to the open sky. The trunks and foliage of hemlocks also re-radiate at night some of the energy they absorb in the day.

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Cougars in New England

1-15-16  cougar tracks  022Are there cougars/mountain lions/pumas/panthers/catamounts (all common names for the same species) in the Northeast? There have been many sightings in every New England state, but official Class 1 confirmation (body, photographs or DNA) only in Connecticut (2011), Massachusetts (1997) and possibly Vermont (1994-mixed DNA results). It depends on whom you talk to, but the consensus of most wildlife biologists is that there may not be a breeding population yet, but they are here (some thought to be of captive origin). There is no question that cougars are extending their range eastward. Through DNA analysis a cougar killed by a car in Connecticut in 2011 proved to have come from the Black Hills of South Dakota. It had traveled about 2000 miles to the East Coast over 2-3 years.

A recent sighting by a friend had me out on snowshoes recently, trying to find traces in the woods where she had had an excellent view of what she identified as a juvenile cougar crossing the road in front of her car. The pictured tracks are what I found and followed. They are definitely cat tracks! Further investigation revealed several sites where parts of a deer had been cached, with typical (of a cat) sheared deer hair (see photo insert) evident. Unfortunately, there was no scat to be found, so adequate DNA wasn’t available for analysis, and thus, it is but one of 50 to 60 reported-but-unconfirmed cougar sightings that Vermont gets each year. It may be officially unconfirmed, but there is no question in my mind which species of cat I was tracking. (Thanks to Squam Lakes Natural Science Center for cougar photo op.)

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Fishers Scent Marking With Scat

1-13-16 fisher bed & scat 002Many animals communicate by scent marking in order to stake out territory. This is done through specialized glands on various parts of their bodies as well as with scat and urine. In addition to defining territory, scent marking may also communicate additional information such as the sex, reproductive status or dominance status of the territory-holder. Fishers are a prime example of a scent marking predator. In addition to scent marking with glands on their feet, fishers rub, urinate and deposit scat often near or on raised surfaces (stumps, rocks, saplings), where their scent is likely to be widely dispersed. Frequently scat will also be found near a fisher’s resting spot.

When marking with scat, fishers are somewhat unusual in that it appears that they can control the size of the scat they leave. While field guides say fisher scat is between two and seven inches in length and roughly ¾” in diameter, this is not always the case. (Neither is it always dark and twisted – some fruit, such as rotting apple in the pictured scat, will cause it to be lighter colored.) One wonders what determines the size of the scat that a fisher leaves. Does it plan on marking a great deal in the coming hours, and so parcels it out in bits and pieces so as not to run out? Or is a large amount not always necessary if it has back-up scent from its feet and body? The pictured scat (to the right of the depression a fisher left while resting at the base of a tree) is less than an inch long, and about 1/3” wide — roughly the size of a white ash seed. Chances are that after spending enough time in one place to melt crusty snow the fisher was capable of leaving far more feces, but it chose not to.

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Dung Beetle Feeding on Bear Scat

10-16 dung beetle 127Wherever there is scat, or dung, there are dung beetles. This is a photograph of a dung beetle in heaven as it has located a black bear’s gigantic (apple-filled) scat, which will provide it with food for a long, long time. Some species of dung beetles (rollers) shape pieces into balls and roll them away and bury them to eat later or lay their eggs on. Some species (tunnelers) bury their dung by tunneling underneath the pile of scat. And a third group (dwellers) actually lives inside dung piles.

Most dung beetles prefer the scat of herbivores. There are always bits of food that do not get digested, and these bits are what a dung beetle feeds on. Dung beetle larvae eat the solids, while adult beetles drink the liquids contained in the scat. A given species of dung beetle typically prefers the dung of a certain species or group of animals, and does not touch the dung of any other species.

Dung beetles have a brain that is the size of a grain of rice, yet they are very sophisticated insects. They use celestial clues (the Milky Way) in order to roll balls of dung in a straight line. Dung beetles are known for “dancing,” which helps them orient themselves after their path has been disrupted. They use their dung balls to regulate their temperature, and cool off. (In very warm climates, around noon, when the sun is at its peak, dung beetles will routinely climb atop their dung balls to give their feet a break from the hot ground. Thermal imaging has shown that dung balls are measurably cooler than the surrounding environment, probably because of their moisture content.) And dung beetles keep track of the number of steps they take and the direction from which they came (instead of landmarks) in order to return to their nest with a ball of dung.

Even though they are remarkably clever, dung beetles can be duped! A flowering plant native to South Africa (Ceratocaryum argenteum) produces large, round nuts that are strikingly similar in appearance, smell, and chemical composition to antelope droppings, which the dung beetles accordingly roll away and bury, effectively sowing a new generation of C. argenteum.

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