Category: animal signs

Avian Woodworkers

Woodpeckers, like other birds, are raising families at this time of year, and they’re consumed by the need to provide food for their young. Because they find much of their food in the bark and wood of living and dead trees, their feeding sites are usually easy to find. The first clue is often a pile of wood chips scattered around a tree base, like the accumulation at the base of the beech tree shown below.

This tree was alive but just barely–the cankers on the trunk tell us it was infected with beech bark disease. The two excavations visible in the photo, plus many more higher on the trunk, were the sources of the widely scattered debris below.

If your timing is good you may find woodpecker scat among the chips. Here’s a close up–this scat was about 1/4 inch in diameter, contained insect exoskeletons, and had some white uric acid on the mostly black surface. Woodpecker scats are delicate and disintegrate when they’re rained on, so you’re only likely to find them in fresh debris piles.

The cavities below were made in a Norway spruce that was very much alive. New holes are often circular, but as they’re enlarged they become elongated and sometimes connect to form long troughs.

So what exactly are woodpeckers that attack trees eating? Contrary to what you might think, they aren’t eating wood! The photo below shows a close-up view of an excavation. Deep in the recesses of the hole the wood is partially decayed, and you can see that it’s honeycombed with tunnels and chambers. These are the galleries of carpenter ants. They’re actually nests rather than feeding sites–carpenter ants range widely on plant surfaces and on the ground, eating other insects as well as sap and nectar. Both living and dead trees may house carpenter ant colonies, and there could be thousands of ants in one tree, so for a woodpecker it’s well worth the work of excavating holes to get at them.

The photo above also shows cuts and grooves made by the bird’s beak as it chiseled the wood away. These beak gouges are large, up to one half inch wide. The pileated woodpecker, the largest and most powerful of our woodpeckers, was responsible for all of the examples shown above. Only a bird this size could make such large holes, not to mention create such wide beak gouges and leave such large scat.

Although smaller woodpeckers can’t produce the same kinds of massive excavations, they still manage to find plenty of food in the bark and outer wood of trees. Hairy or downy woodpeckers searching for wood-boring grubs removed patches of bark from this hemlock tree.

And the dead maple shown below was also mined for wood inhabiting insects. It’s covered with pockmarks made by smaller beaks, as well as some larger gouges, so it was probably a multi-species feeding site.


Wood, whether living or dead, may host many different types and sizes of insects, including the wood-boring larvae of beetles and moths, insects that nest in wood, predatory arthropods that feed on other wood-inhabiting insects, and creatures that simply find shelter in cracks and crevices. Thanks to this diversity, wood is a rich source of food for many different birds.

Red Squirrel Housekeeping

The snow is gone and leaves have not yet filled in the forest canopy, so it’s a great time to look at red squirrel middens. Conifer seeds make up a large percentage of the red squirrel diet, and the animals spend lots of time eating or collecting conifer cones. To get at the seeds a squirrel holds a cone in both front feet and, starting at the bottom, chews off each scale and eats the exposed seeds, spinning the cone as it works its way toward the tip. This is done with typical red squirrel energy, and the scales seem to fly out at blistering speed. The scales and cone cores accumulate around or below the feeding station, and the resulting piles of debris, called middens, can be quite sizable. The mounds in the photo contain mostly the cores and scales of Norway spruce cones. Middens this large must have accumulated over a number of years, probably during the residence of several different animals.

The hole just below the trunk of the closer tree is an entrance to an underground space where cones were stored. These food caches are often located in the spaces around the roots under the middens, but may also be in rock cavities, log piles, or even human structures. They are generally underground where the high humidity prevents the cones from opening.

Red squirrels depend on stored conifer cones for survival over the winter. In late summer and early fall conifer stands resound with the sound of objects hitting the ground as the animals nip the cones in the tree tops. Once a good supply has fallen, the squirrels descend and carry the cones to their underground storage spaces. It’s this habit of creating concentrated supplies in a limited number of locations, called larder hoarding, that allows the animals to inhabit boreal forests with long, snowy winters. Imagine the effort that would be involved if, like gray squirrels, red squirrels had to dig down through a deep snowpack to retrieve each individual food item. With its food stored in larders a red squirrel merely needs to maintain tunnels leading from the surface to the ground-level entrances.

Middens are usually located at the bases of the trees which provided the cones, indicating that the squirrels bring cones up from storage to perches higher in the tree to feed. In the photo above you can see a Norway spruce with several branches (dead but still strong enough to support a squirrel) which could have served as feeding perches. These branches, or ones nearby, are often marked by the squirrels. One such branch is shown in the photo below. The shot was taken from directly above the branch. You can see some partly eaten spruce cones on the ground below in the upper part of the photo, and the dark tree trunk in the lower right-hand area. The branch itself is liberally marked with the fresh gouges of red squirrel incisors, and there are a few older gouges from previous years. The scent compounds left in the wood would establish the resident squirrel’s ownership of that particular real estate.

Middens tell us how much red squirrels depend on conifers for their winter food supply–and it’s not just Norway spruce. Where pines, hemlocks, firs or other spruce species are more common their cones provide the bulk of the winter diet, and similar middens can be found.


In the mixed forests of central New York, middens tell us about the non-coniferous foods that red squirrels also make use of. In the photo above butternut shells with typical red squirrel entry holes are mixed with the spruce scales and cores. I’ve also found the opened shells of walnuts, acorns, and hickory nuts in red squirrel middens. And occasionally a bone fragment, with telltale incisor gouges, sits atop a midden. Red squirrels, like other small mammals, need to boost their calcium intake by chewing on bones, and a familiar feeding perch makes a fine location for a dose of minerals.

Spring Fever among Woodchucks

If you think you have it bad, just consider the woodchuck. The males emerged from hibernation weeks ago only to find the ground covered with snow. There wasn’t much to eat, and the weather wasn’t very spring-like. But no matter–they were more interested in procreation than food or comfort, and they spent their time searching out burrows occupied by females. Upon finding a receptive female the male entered the den and copulated with her, then moved on in search of another one. With nothing much to eat the roaming males, which may have dropped up to 1/3 of their body weight during hibernation, lost even more body mass. Meanwhile, the female woodchucks remained underground and got a few more weeks of sleep.

This delayed emergence is important because, like the males, female woodchucks have already lost weight during hibernation and losing even more would impair their ability to give birth to healthy young. Their appearance above ground coincides with the onset of new spring growth and their condition improves rapidly.

I found the den pictured below in early March. A few inches of new snow covered about a foot of denser old snow, which made for nice tracking. There weren’t any tracks beyond those shown in the photo, so it looked like the animal came out, took a look around, and then went back into the burrow. The mud-on-snow tracks are remarkably clear–check out the right front print just to the right of center.

Finding such unmarred tracks around burrows becomes less likely as the season advances and the animals make more forays to and from their winter refuges. The photo below, also from early March but taken a few years ago, shows the muddy and partially melted evidence of several trips. In both of these cases the weather was still pretty cold and there was a substantial snowpack, so these were most likely males in the throes of spring (or rather mating) fever.

As winter loosens its grip woodchuck tracks start becoming more widespread in fields and forest edges. In the photo below the direction of travel is from the lower left of the frame to the upper right, and the impressions form a zig-zag pattern. Each angle of the zig-zag is composed of two


tracks, the rear positioned roughly on top of or close to the front track from the same side. These are the characteristics of the indirect register walk, the woodchuck’s most common gait. Starting from the lower left, the sequence in the photo above is right hind on right front, left hind on left front, right front with right hind just ahead, left hind on left front. To the right of the first set of left front and hind there are some gray squirrel tracks heading in the opposite direction.

By the way, woodchucks are also known as groundhogs, but I prefer the name woodchuck, because the word derives from one of its Native American names. Woodchucks weren’t as common in pre-colonial times as they are now, but their populations would have been concentrated around cultivated fields so they would have been familiar to Native Americans. They still thrive in agricultural landscapes, and are sometimes seen as pests. From an ecological point of view they are actually beneficial. Woodchuck excavations help to turn over and aerate soils, and their burrows provide homes for many other animals.

The photo above shows a burrow I found after a very cold night. Rabbit tracks led both in and out, but this hole wasn’t dug by a rabbit. Unlike European rabbits, which construct extensive tunnel systems called warrens, our cottontails don’t dig burrows. They get along just fine without underground housing, unless it’s very cold. When that happens they find shelter, and that shelter is often a woodchuck burrow.

Squirrels Share Some Secrets

I’ve been getting more and more interested in squirrels. Like all animals, their lives are shaped by the seasons, and there’s much to discover if you can find and decipher the signs they leave. In late summer squirrels bite off oak twigs to get at the ripening acorns, and the “nip twigs”  (minus acorns) can be found scattered under oak trees. The acorn remnants–shell fragments and partly eaten acorn meats–may also be found on the ground or on nearby logs or stumps where a squirrel has a good view of its surroundings while feeding.

In September I found these apparently uneaten acorns, along with cap and shell fragments, scattered on the ground beneath some red oak trees. The acorns were intact, but every one was marred by brown spots. This puzzled me at first, so I got out my magnifier and took a closer look. I noticed that there were tiny tunnels in some of the brown spots, and one even had a minute, worm-like insect larvae. I also saw indistinct gouges in a few of the brown spots that looked a lot like tooth marks. Mystery solved! The squirrels were feeding on acorn weevils, often found inside acorns and much richer in calories than the acorns themselves.

We’ve had a very wet fall, and fungi have been popping up everywhere. I’ve been surprised to see how fond squirrels are of mushrooms. I’ve repeatedly come across mushrooms which had been plucked from where they had grown, carried to some other spot, and partly or almost completely eaten. Bite marks sometimes showed along the edges, and there were always discarded pieces scattered around–squirrels seem to be sloppy eaters. Slugs and snails also seem to love mushrooms, but they simply make broad, shallow gouges in the caps and the mushrooms remain standing where they grew.

When the weather turns colder squirrels give up their summer leaf nests and move into more sheltered lodgings, often in hollow trees. Instead of using leaves, they line their nests with fibrous material. The inner bark of this dead branch was stripped off by a squirrel and used to provide warm insulation for its nest. The smoothly denuded wood surfaces and hanging remnants are typical of squirrel work. In addition, there are usually a few gouges made by the animal’s incisors somewhere in the debarked area. Dead branches are the most common source of good nest lining material, but the bark of living honeysuckle and other shrubs is a favorite material where they are available.

You may have been wondering which squirrels I’ve been talking about. Actually, I’ve purposely avoided naming them because I’m often not sure. Our mixed forests host both red and gray squirrels, not to mention northern and southern flying squirrels, and it’s often difficult to know which species left a particular sign. I suspect that the oak nip twigs and the weevil feeding were done by gray squirrels, but red squirrels also feed on acorns. I’m pretty sure both red and gray squirrels eat mushrooms, and all of our squirrels line their winter nests with fibrous material. There are some types of sign–certain kinds of marking, and large middens under conifers–that can definitely be attributed to a particular species; more about those in future blogs. Until then, we’ll adopt the wise tracker’s attitude and recognize the limits of our certainty.

Busy Bears

I just spent a wonderful week in the western Adirondacks, and I was able to indulge in one of my favorite activities: exploring the Independence River on foot–in other words, wading. Besides being breathtakingly beautiful, the Independence is small enough to be safely waded when water levels are low, and there are plenty of sandbars and silty edges where tracks can be found. These bear tracks were the find of the day. The bear was traveling from left to right, and my dog (she likes to explore rivers with me) left tracks below the bear’s,  going in the opposite direction. The first bear print at the upper left is the right front, and just to its right is the right rear. A little farther to the right is the left front print and to its left the left rear. The pattern of rear print ahead of front from the same side tells me that the bear was moving at an overstep walk–a gait often used for relaxed investigation or leisurely travel.

I was excited to find bear tracks because they’re not always easy to find, especially in late summer when the animals are spending much of their time in forests, overgrown clearings, or other relatively untrackable places. The bear may have visited the river to drink, or perhaps to use the shoreline as an easy travel route to a new food source. But even if there are no tracks to be found, there are usually plenty of other indicators that bears are in the neighborhood. Bears use a variety of marking techniques to communicate with other bears, and these marks are often prominent and long-lasting. A bear raked this white pine tree with its claws, leaving fresh claw marks which oozed with copious sap flows.

Man-made structures like signs and lean-tos are often targets of bear marking. On a different day during my recent visit to the ‘Daks I walked along a forest road where posts had been set to mark the locations of culverts. It was clear that bears were habitually using that road–many of the posts, like this one, were ravaged by bear bites. The brighter wood exposed by the bites stands out to our eyes, but for the bear the scent of the saliva-soaked wood is probably more important.

Teeth and claws aren’t the only things bears use to make their presence known. They often rub against trees or wooden structures leaving a personal scent signature from the oils and sebaceous chemicals in their fur. Another post along that same forest road was decorated with hairs left by a bear that had done just that.

And then there’s always scat. Piles of bear scat provide long-lasting samples of what bears are eating. This time of year in the Adirondacks black cherries are a favorite item, as demonstrated by this example. Elsewhere the skins and seeds of apples, grapes, viburnums and berries; squash and pumpkin seeds; corn kernels; or the shells of hickory nuts, beechnuts and acorns may show up in late summer scat. This is the season of ursine hyperphagia, the insatiable hunger that drives bears to eat almost 24 hours a day. The thick layers of fat they put on will allow them to survive their long winter hibernation.