Bountiful 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.
Red Foxes have a very diverse diet – birds, small mammals, snakes, frogs, eggs, insects, fish, earthworms, berries, fruit — the list is endless and this diversity is part of the reason that foxes thrive in almost any habitat. However, the fox whose tracks I was following recently passed up a meaty meal – that of a Spotted Salamander. The story the tracks tell suggests that the fox dropped the salamander after unearthing it from its hibernaculum and carrying it some distance. It’s likely that it had detected the sticky white toxic liquid that Spotted Salamanders secrete from poison glands in their skin when they are threatened. Unfortunately, detection did not occur in time to save the salamander’s life. Either its experience with the fox and/or freezing temperatures killed the salamander, preventing it from going back into hibernation. (Note red fox tracks to right of salamander.)
Although muskrats are primarily nocturnal, you occasionally see them in the daytime, especially in the spring and fall. They often reside in ponds or marshes, where they live in the pond bank or build their own house out of mud, cattails and other available plant material. Muskrats are herbivores, favoring cattail roots, arrowhead, bur reed, pickerelweed and other aquatic vegetation. The pictured muskrat is not feeding, however — more often than not muskrats eat their food where they find it, especially during the warmer months. It is doing its share of parental care — this is the time of year when the first of several litters of muskrats are born. While the mother nurses her four or so young, the father spends time gathering bedding material for his offspring. The muskrat in this photograph spent a morning cutting and gathering several mouthfuls of grasses growing by the side of the pond. When he couldn’t fit one more blade of grass in his mouth he would scurry down the bank and disappear into a burrow which most likely led to a chamber where his young are being raised. Like their beaver cousins, muskrats tend to keep a tidy house and forage for fresh bedding for their young with some regularity.
Long before the beetles and flies move in to get their share of a dead carcass many meat eaters have usually taken advantage of the easy meal. A motion camera on a dead white-tailed deer recently captured the images of 12 scavengers over a six day period. They included an opossum, several coyotes, a raccoon, red fox, striped skunk, American crow, raven, turkey vulture, red-tailed hawk and bald eagle. By the end of this time, there wasn’t much left except for bare bones, which, as winter progresses, will eventually be eaten as well. Not a shred is wasted – nature knows how to recycle and has been doing it for eons.
A 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.
Some birds, especially those that eat seeds, buds, leaves and nuts, such as ruffed grouse, eat food very rapidly, faster than it can be passed through the digestive system. These birds usually have a pouch-like crop where food is stored to be digested later, when the birds are not out in the open, susceptible to predators. (see 10-24-12 Naturally Curious post) This rapid consumption and storage of food by grouse, often at dawn and dusk, is referred to as “budding.” Examining the contents of road-killed grouse crops is one way of learning more about this adaptive behavior. Assuming some of my readers might (?) share my curiosity about the diet of grouse, I occasionally post the contents of a grouse crop I’ve recently examined. My most recent dissection revealed that the grouse had switched from its herbaceous summer diet to its more woody winter diet — its crop contained no less than 232 male birch flower buds, or catkins. (Disclaimer: This crop was not that of the grouse that was the subject of the 11-9-12 post.)
According to the predictions on eBird’s annual Winter Finch Forecast, several species of northern seed-eating birds will be moving south this season due to a poor cone crop in the north. As of mid-October, pine siskins (pictured), purple finches, red-breasted nuthatches and red crossbills have already been showing up in larger numbers than usual in New England, well south of their normal wintering grounds. This type of movement is referred to as an irruption. Because of a widespread crop failure of fruiting and cone-bearing trees in Canada, we may be lucky enough to have a glimpse of crossbills, redpolls, pine grosbeaks and evening grosbeaks this winter. The latest to arrive at my feeders are pine siskins, whose irruptions often occur on a two-year cycle. Their numbers in New England were great during the winters of 2008 and 2010, so the pine siskin irruption this year is right on time.
Shorter days and longer nights trigger a flurry of activity for beavers. There is a lodge to be built, rebuilt, enlarged or repaired and a dam to be built, repaired or reinforced. As, or more, important than these tasks is cutting, gathering and transporting a supply of food for winter. Once the pond is frozen, the only food available to beavers is that which they have stockpiled under the ice. Thus, beavers spend many an autumn night adding to a growing pile of submerged branches close to the lodge. More thought is put into the harvesting of a winter food supply than one might imagine. Before cutting down a tree a beaver often tests its readiness by biting into the bark. If it is not in just the right condition — for instance, if there is still too much sap in the tree — they may speed up the drying of the bark by girdling it, and returning in several days to cut it down. If limbs and branches are stored underwater before the bark is ready, they will ferment and sour, making them unfit for food.
Possibly because of the importance of summer fruits in their diet, Cedar Waxwings (Bombycilla cedrorum) are late nesters, but by late August adults have begun their migration to the southern states and Central America. This year’s young are beginning this (roughly) 900-mile flight now, a month after their parents have left. You can often find waxwings feeding in crab apple and other fruit trees where they stop over during their flight to refuel. Juvenile birds lack the sleek look of adults — the red wax-like feather tips for which this bird is named have not developed, and the color of their plumage is much duller than that of the adults.
Bumblebees are nothing if not perseverant. Prying Bottle Gentian’s (Gentiana andrewsii) petals open is a monumental task, and one that few insects, other than large species of bumblebees, attempt — much less accomplish. The relationship of bumblebees and Bottle Gentian is an example of a mutualistic association — the bees benefit by having exclusive access to a bountiful and sugary nectar supply, and the plants benefit by attracting “loyal” pollinators that improve the chances for cross pollination.
Northern Watersnakes can be found in rivers, ponds and bogs throughout New England, except for northern Vermont, New Hampshire and Maine. They spend time foraging both day and night for fish (61% of diet), frogs and toads (21%), salamanders (12%) as well as insects and crayfish at the water’s edge. (Snake jaws can separate at both the front and back, allowing them to eat impossibly large prey , such as the catfish in Chris Crowley’s photograph.) They also spend a great deal of time basking on rocks and overhanging branches. Northern Watersnakes can be formidable looking – they can grow over four feet long – but while they can be aggressive if threatened, they are not poisonous. Watersnakes give birth to up to 70 (typically 20-40) live young between August and early October.
Although Great Egrets (Ardea alba) do breed sporadically as far north as Vermont, seeing one in northern New England is always noteworthy. The likelihood of a sighting increases as summer progresses, due in large part to the phenomenon of post-breeding dispersal. After young Great Egrets have fledged, individuals wander well outside their typical breeding range, as far north as southern Canada. The northward dispersal of juvenile birds peaks in August and September. (This Great Egret is about to dine on a crayfish.)
Black 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). In the fall, prior to going into hibernation, 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 by 35% in some cases. Their daily food intake goes from 8,000 to 15-20,000 calories (that’s roughly equivalent to 70 McDonald’s cheeseburgers). Signs of their foraging for grubs and beetles, such as the excavated base of the snag in the photograph, can be found with relative ease at this time of year, if you live where there are black bears. If you do share their territory with them, be forewarned that they have excellent memories, especially for food sources. Be sure not to leave food scraps or pet food outside (my compost bin was destroyed last year but I have no solution for that particular problem), and if you really don’t want any ursine visitors, it’s best to not start feeding birds until most black bears have entered hibernation – late December would be safe most years.
Now is the time when your garden is most likely to have visits from resident woodchucks. These large, herbivorous rodents are eating fast and furiously as the days get shorter, in an effort to put on a layer of fat that will sustain them through hibernation. The middle of the day is typically spent sunning themselves, but early morning and evening will find woodchucks eating and putting on a layer of fat equaling about a third of their weight. They lose anywhere from 20% – 37% of their body weight during hibernation. If they don’t gain enough weight now, they won’t survive until green grass and other plants are available again in the spring. Hopefully knowing this will make sharing your garden with an uninvited guest a bit easier.
Although Great Blue Herons are colonial nesters, they forage by themselves, usually by slowly wading or standing in wait of prey in shallow water. Fish are the mainstay of their diet, but they also consume amphibians, invertebrates, reptiles, mammals, and birds. When prey is located (by sight), the heron rapidly thrusts its neck forward and grabs it with its beak. If it is small, it is sometimes tossed in the air before it is swallowed, as the photograph depicts. Most prey are swallowed whole.
Common Mergansers are primarily fish-eating ducks. Young mergansers require over half a pound of food per day during their first summer, and often supplement their fish diet with insects, mollusks, crustaceans, worms, frogs, small mammals, birds and plants. The pictured immature Common Merganser had just downed a crayfish when it spotted a frog which it succeeded in catching and eventually swallowing.
A weevil is a type of beetle whose mouthparts are formed into a long snout, with one antenna on either side of it. The snout is used not only for feeding but also for making cavities in buds, fruits, seeds, stems, and roots of plants, where eggs are laid. When the weevil larvae emerge, they feed within the plant. There are 60,000 species of weevils, all of which are herbivorous and most of which are less than ¼ ” long. The species of weevil in the photograph was on many of the black-eyed Susans that were blooming in an unmowed field, and all of them appeared to be feasting on pollen. Many weevils are pests of plants such as cotton, alfalfa and wheat. You may have even found them inside your house devouring your cereal or flour.
If you’ve been traveling on sunny dirt roads lately, chances are that you have seen White Admiral butterflies all over them. They are in the road to obtain salts and minerals that have leached from the soil into standing puddles and moist dirt. Because butterflies do not have chewing mouthparts as adults, they must drink their meals. While nectar is their main source of nutrition, males often supplement their diet with these minerals. The act of acquiring nutrients in this manner is referred to as “puddling.” If there’s no water around, a butterfly may regurgitate into the soil and then drink in the hope of retrieving minerals. In addition to finding butterflies on dirt roads, look for them puddling on animal scat.
Beavers are meticulous housekeepers, in that they almost always defecate in the water, not in their lodge, and rarely on land. The best place to find their scat, should you be so inclined, is where they have been working for an extended period of time — for example, in the water adjacent to their dam. Their scat consists of kumquat-size pellets, which, as you might expect, are full of tiny bits of woody fiber. The pellets are essentially little balls of sawdust, and disintegrate easily if disturbed. Their light color makes them visible even under water. Congratulations to all who guessed correctly — I’ll make the next mystery post even more challenging!
Although you would think that no predator would think of preying on, much less eating, a striped skunk, there are a few mammals, including coyotes, foxes and bobcats, that do just that, but only if they are in danger of starving. One predator that routinely dines on skunks is the great horned owl. One summer night I made out the silhouette of an owl flying in my direction, and as it flew by me its identity was confirmed by the skunk-like odor that accompanied it.
Contrary to their name, fishers seldom eat fish. While they prey on a wide range of animals and even plants, their preference is for small mammals (80% of their diet), snowshoe hares and porcupines. Because fishers are well equipped to kill porcupines, and because there is little competition for them, porcupines are an important prey of fishers –up to 35% of fisher diet samples contain the remains of porcupines, as this photograph of fisher scat attests to. There is no mistaking the bumpy porcupine foot pads (and quills)!