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Dens

Red Fox Vixens Cleaning Out Dens

2-14-18 red fox den 049A2731You may have heard or seen Red Foxes barking in the past few weeks – a sign that their mating season has begun. The skunk-like odor of fox urine at this time of year (particularly the males’) indicates where they have marked their territory. Most of the year Red Foxes are solitary animals, but in January and February it’s common to find the tracks of a pair travelling together.

Vixens (female Red Foxes) are already scouting out this year’s den site. They often clean out several dens on their territory, one of which they choose for their litter. The typical fox den is on a hillside in sandy or soft soil, often in a forest but close to an open area. They may dig their den, or modify the burrow of another animal. Usually there is a source of water within 300 feet or so of the den. There are several entrances, the largest being about ten inches in diameter. The same den may be used for many years, and eventually taken over by a daughter upon her mother’s death.

Finding a fox den is easiest now, when the excavated dirt is obvious on the snow, and tracks leading to and from it are visible. In roughly two months there may be anywhere from one to ten (usually four or five) kits being raised inside the den.

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Red Fox Vixens Preparing Dens

red fox dens4With their breeding season nearly at an end, red fox vixens are preparing for the arrival of a litter of pups in March or April. This involves locating and cleaning several dens, and then choosing one in which to give birth and raise young. An adult female red fox may use the same den year after year; eventually one of her daughters may take it over.

While specific den locations vary, most are on sandy hillsides, often in the woods but close to an open area, and usually there is water within 300 feet or so. A den typically has several entrances, with the main one measuring about ten inches in diameter. At this time of year (if there is snow on the ground) it is relatively easy to locate fox dens, due to soil that has been removed and scattered on the snow.

Vixens often renovate an abandoned woodchuck burrow, but occasionally den underneath an outbuilding, in a hollow log, rock pile or other sheltered area. Pictured are a typical hillside den as well as an abandoned beaver lodge that has been renovated by a fox.  Scat (located about 2 o’clock in the photo) deposited near the entrance of the lodge indicates that this may well be a den that will be used for raising young.

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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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Black Bears In No Hurry to Den This Year

11-16-15 black bear apple scat 026Bountiful acorn and apple crops have enabled black bears to delay denning this fall, as this recently-discovered apple-filled bear scat attests to. Denning is triggered by a seasonal shortage of food, low temperatures, and snow cover on the ground. When these conditions cause bears to den, they typically stay within their summer range boundaries. On average black bears enter their dens in November and emerge in April, but this varies considerably with crop and temperature conditions.

Denning sequence usually begins with yearlings, followed by pregnant females, then solitary females, females with cubs, adult males, and last, subadults (not sexually mature) of both sexes. Most dens are excavated below ground, and on well-drained, upland sites. Rarely are they re-used in consecutive years. Adult males are the first to emerge in the spring, followed by subadult males and females, then females accompanied by yearlings, and finally, females with cubs of the year.

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Porcupines Marking Dens

3-25-15 porcupine den IMG_9681Often, at this time of year, porcupines stake out their den trees (if they’re not inhabiting rocky ledges) by eating patches of inner bark, or cambium, with the exposed fresh inner wood announcing their occupancy. Typically, if a tree den is used year after year, they gnaw off a portion of bark each year, sometimes eating the old, scarred portion which, due to previous chewing, lacks cambium cells, indicating that this behavior is not for the purpose of obtaining nutrients. (photo: porcupine chewing near hollow tree den entrance)

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Black Bear Dens

2-25-15 bear dens1Black bears den in a range of locations, including under logs and stumps, under the branches of a fallen tree, and inside caves and hollow trees. Most adult black bears are not completely protected from the elements while they are hibernating and/or raising cubs, as there is usually a fairly large opening and the bear is exposed to the cold air. The amount of exposure can vary tremendously, from a relatively protected hollow under a log to complete exposure within a dense thicket or stand of conifers. Pictured are two black bear dens where cubs were raised; one is under a fallen tree and the other is in the middle of a stand of spruces.

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Porcupines Entering Winter Dens

porcupine IMG_2597During the summer, porcupines are almost always found out in the open. At the end of October/beginning of November porcupines den up for the winter in the Northeast, with up to a dozen porcupines sharing the same den. While some adult males will spend days at a time in a conifer, most porcupines seek out rocky crevices in which to spend the day, with a smaller number finding shelter in hollow trees. Porcupines are hardy creatures – while dens do protect porcupines from heat loss, they contain no insulation, the entrances are open and the porcupines don’t huddle together for warmth. In addition, porcupines emerge from their dens to feed at night, when outside temperatures are lowest. (And yes, that is porcupine scat that is stuck in/on the porcupine’s quills.)

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Red Foxes Preparing Dens

2-25-14  red fox den 013Red Foxes will be begin giving birth in about a month, so the time for preparing their den has arrived. While it’s never very hard to see a fox den (due to the pile of dirt at its main entrance), they are most obvious now, when the dirt removed by the foxes is conspicuous against the white snow. Red Foxes seldom dig their own den. Rather, they take over a woodchuck’s abandoned burrow, or, in some cases, forcibly drive the woodchuck out (and sometimes devour it, as well). They den in woodlands as well as fields, usually on a sandy knoll where they can observe the surrounding territory, and where their den will be well drained. Most dens have one or two main entrances. The tunnel usually slants downward to about four feet beneath the surface and then extends laterally for 20 to 30 feet and resurfaces. An enlarged chamber along the main tunnel serves as a maternity den.

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Raccoons Active During Warm Spell

1-21-14 raccoon tracks 049During the recent warm spell raccoons were actively roaming the woods, visiting open water and leaving signs of their presence. When cold weather arrives in the fall, raccoons search out hollow trees, logs, crevices, etc. in which to den. They become dormant, but do not hibernate. If the temperature rises above 30 degrees F. at night as it did during the last week, they become active, but now that the temperature has dropped to sub-zero temperatures at night, they have retreated back to their dens. During mild winters, raccoons remain active; during colder winters, they are usually dormant between late November and March. A winter with vacillating temperatures, such as the one we’re experiencing, has them going in and out of dormancy.

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Beavers Refurbishing Lodge

10-14-13 refurbished beaver lodge 248This is the time of year when the industriousness of beavers can determine whether or not they survive through the winter. There are three major tasks for a beaver colony to tend to in the fall: refurbishing their lodge; strengthening and repairing their dam; and cutting and storing their winter food supply. They tend to perform these tasks in this sequence, tackling the lodge first. If the water level is high, the beavers will raise the floor of the lodge and the roof of the sleeping chamber. Every fall they add new material to the exterior of the lodge to strengthen the entire structure – typically sticks intertwined that create walls two feet thick or more. At this point the beavers coat the lodge with mud that they dredge up from around the base of the lodge (which greatly increases the depth of the water near the lodge). The apex of the lodge is not coated, allowing fresh air to filter down into the sleeping chamber. Once cold weather arrives, the mud hardens to the consistency of concrete, making the lodge is impenetrable to predators that can approach the lodge once the pond freezes. (In photo, note the fresh eastern hemlock branches and mud that have recently been added to the lodge.)

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Black Bear Hibernation Ends

3-20-13 black bear track IMG_7204Recent discovery of black bear tracks and scat confirm that hibernation has come to an end, at least for some bears. During the winter black bears lose an average of 23% of their body weight. Because there is a scarcity of food when they emerge from their dens, black bears continue to subsist off the fat that they put on last fall, and thus continue to lose weight. The diet of black bears is high in carbohydrates and low in proteins and fats. When hibernation is over, they head for any available succulents and protein-rich food, including bird feeders.


New Children’s Book by Mary Holland

FerdinandFoxCover PhotoDo you know a 3 – 8 year old who loves animals and would enjoy getting close-up views of the antics of a red fox kit during the first summer of his life? My second children’s book, Ferdinand Fox’s First Summer, has just been published by Sylvan Dell in both hardback and paperback. I have been lucky enough to have had the opportunity to observe and photograph young red foxes as they interact with each other and with their parents. This book consists of a selection of these photographs, accompanied by text and an educational component at the end of the book. Look for Ferdinand Fox’s First Summer in your local bookstore. If they don’t carry it, you would be doing me a huge favor by asking them to. Thank you so much. My next children’s book is on Beavers and will be coming out in the spring of 2014. (I am still looking for a publisher for Naturally Curious Kids!)


Coyotes and Beavers

3-12-13 coyote & beaver lodge2 IMG_6223A study of coyote prey (through stomach contents) in the Adirondack Mountains of New York revealed that beavers were second only to white-tailed deer. This photograph shows that, possibly for the last time this winter, a coyote recently took advantage of a still-frozen-but-fast-thawing pond by walking across it in an attempt to reach an active beaver lodge. Once there the coyote attempted to dig into it in order to reach the inhabitants. A hard, two-to three-foot-thick wall of frozen mud, logs and sticks kept the beavers well protected, as it was designed to.


Watch and Listen to Six-week-old Black Bear Cubs

2-24-13 black bear cub IMG_0386I can’t let another minute pass without bringing a website to my readers’ attention, as activity has really picked up recently. The live-cam installed inside a bear den in Ely, Minnesota at the North American Bear Center captures the sounds and movements of a mother bear and her two six-week old cubs 24 hours a day. Everything from the mother’s birth to the fall and rescue of a cub has been recorded. Enjoy part of your snowy (or not) Sunday by taking a look at this ursine family. You may have to have considerable patience before seeing a cub, but it will be worth it, and you’ll hear them night and day! It will be obvious to you that female black bears with newborn cubs do not have the luxury to go into as deep a hibernation as their mates, who are blissfully asleep in their own den. Go to http://www.bear.org/website/live-cameras/live-cameras/lilys-den-cam.html and click on “live stream” in the upper right hand corner of the picture of the bear to view live coverage. You can also see tapes of past activity, both here and on “Lily the Black Bear’s” Facebook page.


Porcupine Housekeeping

1-31-13 porcupine in ledge den IMG_2389A recent exploration of some rocky ledges, a favorite winter denning site of porcupines, revealed a virtual maze of trails leading to roughly a dozen crevices where porcupines sought shelter. A look inside these crevices confirmed that porcupines leave something to be desired when it comes to keeping house. Unlike many other animals that keep their dens pristine (e.g. beavers only defecate in water, never in their lodge), porcupines don’t feel the necessity to roust themselves when nature calls. As a result, the floor of their den consists of years of accumulated scat (and urine). In some cases, the pile of scat in these ledge dens was so high that it made you wonder how a porcupine could even fit into the crevice, and indeed, in some cases, porcupines do have to dig their way out of their den. When it became aware of my presence, the pictured porcupine assumed its characteristic defense posture, exposing its quill-filled back and upper tail surface to the intruder. It needn’t have worried, as the opening was barely wide enough to get the camera into, much less the photographer!


Mink Tracks & Dens

If you take a walk along a small wooded stream that has many fallen trees along its banks, you can expect to find mink tracks somewhere along it. These wetland-loving weasels dig their dens in river banks, often under tree roots, and judging from their tracks, visit them frequently. It is not unusual for one mink to have several dens which it uses as resting spots along a stream. Mink spend a lot of time in the water hunting for fish, aquatic insects and crayfish. Mink are good swimmers and can dive as deep as 16 feet. Tracks will run along the frozen sections of a stream, and then disappear into the water, only to reappear on the ice further downstream when the mink decides to travel on solid ground again. 1-8-13 mink tracks along river IMG_0175


Woodchucks Preparing to Give Birth

Roughly a month ago woodchucks were at the peak of their mating season.  New England’s largest member of the Squirrel family is about to give birth to two to six young chucks. In preparation for this event, dead grasses are gathered and carried by mouth to the underground nest chamber, which is about 15 inches in diameter. Woodchucks are tidy rodents — the female covers her young’s waste with new bedding placed directly over the old, and when the nest becomes too bulky or unsanitary, the matted material is removed and fresh bedding is added.


Red Fox Kits Emerge from Den

For the first month or so of their lives, red fox kits remain in their den.  They are born with a coat of dark gray fur, which is replaced when they are about a month old and starting to emerge from their den.  Their second coat is sandy-colored and blends in well with the soil surrounding the den entrance, where the kits spend most of their time.  By late June they will have acquired the red coat we associate with adult red foxes. Meanwhile, if you know the whereabouts of an active den, there is no better or more fun time of year to watch the antics of young kits than right now – they entertain themselves while their parents are out hunting by pouncing on each other, having mock fights, playing tag and chewing on all kinds of things from sticks to feathers – all of which is interspersed with frequent naps. 


Woodchucks Emerging and Mating

A sure sign of spring is the emergence of woodchucks, the largest members of the Squirrel family in New England, after a long winter’s sleep. Their arousal is easily noted, for when the males wake up, they do some excavating of their tunnel, scattering dirt all around it which is easily spotted on the snow (if there is still any snow left).  Equally obvious is the muddy trail they leave when in search of a female.  Mating takes place in March and April, and the resulting  litters of 2 to 6 young are born a month later.