Tag: red squirrel

Logs

Living creatures see the world in terms of significant objects. We humans are no exception–for us significant features would be such things as chairs, doorways, computers, streets, buildings, picnic tables, traffic lights….you get the idea. For wild animals rocks, thickets, streams, cliffs, and trees come to mind. And then there are logs–items that we usually ignore unless we’re looking for a place to sit. Downed logs are important to many animals in many different ways, and the evidence is often plain to see.

A chipmunk sat on the log in the photo above to eat a red oak acorn. In order to get at the edible meat, the animal tore narrow strips and small chunks from the outer covering. Logs serve as feeding platforms for many small rodents, including red and gray squirrels, and the leftovers often reveal who the diner was. When squirrels feed on red oak acorns, the shell fragments left behind tend to be larger than those discarded by chipmunks.

The log above was used by a red squirrel feeding on red pine cones. As the squirrel fed it dropped the cone scales and cores on the ground in front of the log to create a large midden. Red pines are self-pruning trees and don’t offer many branch perches, so although red squirrels prefer the safety of branch perches, they sometimes need to use more earth-bound objects. Logs, stumps, and rocks can offer a good view of the surroundings and allow the animal to detect danger.

And how do we know it was a red squirrel? Although gray squirrels do sometimes eat conifer seeds, they don’t store them the way red squirrels do, and they never feed on enough conifer cones to create middens the size of the one in the photo.

Tracks on logs tell us that they can also serve as travel routes. Of course we need snow to see this kind of evidence–the light snowfalls of early winter and early spring often show the prints of animals that walked on logs. The coyote that made the tracks in the photo above found the log to be a convenient route through an area obstructed by branches and undergrowth. Walking on logs may also be quieter since leaves and debris can be noisy, even under a layer of snow. Another advantage of walking on logs is a better view. The greater elevation helps prey animals to detect danger, and predators to detect prey. I’ve found many different tracks on logs–the list includes squirrels, white-footed mice, chipmunks, raccoons, bobcats, bears, red and gray foxes, coyotes, fishers, minks, and weasels.

Logs offer these same advantages when there’s no snow, so we can be sure that animals also walk on logs in warmer weather. Without snow their tracks are difficult to detect, but we may still find evidence of their passing. A long-tailed weasel left the scat shown in the photo above on a mossy log. The scat was not quite 1/4 inch in diameter and contained hairs from a small mammal.

The logs in the photo at the head of this article are ones I visit regularly, and they often accumulate the scat of several different kinds of animals. This suggests that they have some special importance, but I’m not sure exactly why. The log in the foreground bridges a low, rocky gully, but the more distant one lies on more level ground. Both logs are large, but there are other logs nearby that are as big or bigger and don’t accumulate scat. Whatever the reason, we can be sure that each species that travels those logs takes note of the messages left by other creatures.

In addition to serving as perches, travel routes, and bulletin boards, logs may be a source of food. This log was torn open by a black bear in search of the grubs that were living and feeding in the rotting wood. Bears are not the only creatures that find food in logs–skunks, raccoons, and woodpeckers also open logs in search of edible morsels. But the size of the fragments and the distance to which they were thrown could only have be the work of an animal as powerful as a bear.

Have you heard a grouse drumming this spring? At this time of year ruffed grouse are looking for mates. The males seek out large logs, and once they find a log that offers a stable and well elevated surface they send out a kind of drumming sound with their wings. The low sound travels long distances, and the elevation of the log gives it even more range. Females are drawn to the sound, and if they’re impressed they will mate with the male. In the photo above I’m perched on a grouse drumming log, taking a photo with my old SLR camera. In front of me on the log you can see several grouse scats.

Whether they’re dinner tables, highways, message boards, pantries, stages, or even just obstacles, logs are significant objects for inhabitants of the natural environment. The evidence they present can reveal unseen dramas in the lives of animals. So before you sit on that log, take a look at it. You might be rewarded with a message that opens a window into the life of a wild creature.

Incisive Communication

Communication is an essential part of life for all animals. For squirrels and their kin spring is a time of intensive communication, as they select nest sites and prepare to birth and raise young. And the leafless canopy of early spring affords good visibility, so it’s a great time to spot the messages left by these animals.

The strong, sharp incisors possessed by all rodents–two in the upper jaw and two in the lower–are perfect tools for inscribing messages. In the photo below bright gouges show where a squirrel bit into the sides of a narrow cleft in a tree. The cleft was at eye-level, so the reddish marks of the animal’s incisors were easy to see. After making the bites the animal may have rubbed its cheeks on the bark to leave a scent message. Squirrels have a well developed sense of smell, so the saliva left in the bites and the scent from the cheek rubbing may have been even more meaningful than the visual marks.

Squirrels also create “stripes” on tree trunks. In the next photo gray squirrels–probably more than one–made many bites in an elongated zone between four and six feet off the ground along the trunk of a white oak. If you look carefully you’ll see that the individual bites vary in color, from bright reddish (the most recent) through grayish red to dull gray (the oldest). The varying age of the bites indicates that this stripe has been worked in the same way over several years. The individuals making the bites probably also did some cheek rubbing, so the bark would have been perfumed with an abundance of scents.

Marks like the ones pictured above are usually found in the general vicinity of nesting or feeding areas, but sometimes the bites seem to indicate a claim to a particular nest site. I’m not talking about summer nests, the leafy dreys seen high in the branches of large trees. In areas with cold winters, both winter and birthing nests are located in safe, weather-proof sites like hollow trees or underground cavities, and the supply of good sites may be limited. The hole shown in the photo below was located about 20 feet up in a large tree. There was probably a perfect nest cavity inside–the opening looked well used, and the varying intensity of the bitten areas suggested that the site had been used for at least several years. By marking the opening, the resident squirrel was able to establish ownership of its chosen refuge.

Squirrels are not the only creatures associated with tree holes. The openings shown below were made by pileated woodpeckers. From a distance the bright margin of a woodpecker hole may look like the chewed edges of a squirrel hole, and the size and shape may be about right. But it’s easy to tell that these holes are not squirrel holes. The first clue is their rough, splintery margins. Another clue is the number of holes–in this case there were five similar openings distributed along the trunk. These holes were made for feeding, and they’re distributed up and down the trunk because the insects the woodpecker was seeking–probably carpenter ants–had colonized much of the tree. Woodpecker holes are often more irregular in shape, and when that’s the case it’s easy to tell that they weren’t chewed on by squirrels.

Whether a mark was made by a red or a gray squirrel is often hard to determine–both are known to make stripes along trunks, and both probably mark the entries to nest cavities. Flying squirrels may mark in similar ways, but I haven’t been able to find any mention of that in the tracking literature and I don’t have any examples to share. If anyone knows the location of a definite flying squirrel nest hole, I’d love to hear about it.

Chipmunks tend to use underground refuges rather than tree cavities, and I haven’t seen anything in the literature about chipmunk marking. But a few weeks ago I came across the hole in the photo below, located a little above my head in a small tree. It puzzled me at first because the chews looked rougher and more irregular than the typical squirrel chew. But the mystery was solved when I stood on my tip toes to get a closer look. Out of the hole came the frantic chittering of a chipmunk. The animal sounded so upset that I left quickly, but I thanked it for showing me what a chipmunk can do with its teeth.

Wild Lives Hang by a Thread

When small rodents feed above ground they usually leave obvious signs of their meals in the form of inedible remains. I love finding these because they reveal a lot about what, how, and where these animals have been eating. It’s especially exciting when I see something unusual, and that’s exactly what happened a few weeks ago. I was walking along a seldom-used (but familiar to me) trail which, at one spot, runs along the edge of a large depression in the ground, about the size of a small room. As I scanned the sunken area I saw odd scatterings of small things on the snow. Looking more closely I saw that the scattered bits were maple seeds. There were red squirrel tracks in the same areas, and many of the seeds had been opened. I knew that gray squirrels fed on maple seeds, but this was the first time I had observed evidence of red squirrels doing that.

Here’s close-up to show that the seeds were really being eaten. If you look at the one near the center of the photo (the one with the winged end pointing toward the upper left) you can see that it was opened at the base.

In our region red squirrels normally favor large stands of conifers, and the most common feeding sign consists of piles of cone scales and cores under their favorite trees. Cavities among the roots are used for food storage, and dead branches part way up the trunks offer well protected feeding perches. So my discovery of feeding sites on the snow surface, the diet of maple seeds, and the location–a mixed forest of sugar maple, red oak, yellow birch, beech, white pine, and hemlock–seemed unusual for a red squirrel. But because I was familiar with the area from warmer seasons, I knew that the sunken pit was actually an old cellar hole, probably part of a 19th century homestead. The stone walls were partially collapsed, and the rocky jumble provided perfect spaces for food storage. It appeared that this red squirrel had discovered an attractive abode.

As I explored the place I noticed another hole, shown in the photo below. This hole was bigger and looked well used–it was probably the main entry to the squirrel’s underground accommodations. But as I examined it I realized that something violent had happened. There were some spots of blood near the opening, and some of the snow around it was disturbed. There were also tracks. If you look carefully at the photo below you’ll see two small impressions in the top center. And to the left of the large blood spots some very different tracks are visible.

This called for some tracking detective work. To show the details better the next photo is a close-up. Above and to the right of the hole the snow is compressed and disturbed, and spots of blood can be seen on the left side (along with a smaller spot to the right). Although they’re faint, you can see the two small prints at the top of the frame.

The tracks to the left of the hole are particularly intriguing–the clearest ones are shaped like the letter K lying on its back. These are owl tracks, probably made by a barred owl. In an owl track the vertical stalk of the K is on the inside of the foot and the shorter angled branches are on the outside. There are two prints made by the owl’s left foot, one above and partly on top of the other. The track of the right foot is less clear, but lies below and a little closer to the hole. This means the bird was facing to the right when it made the tracks. To help you sort all of this out I’ve repeated the photo above with the owl and squirrel tracks labelled.

Here’s my take on what happened: the victim was emerging from its hole when the owl swooped down and seized it in its talons. As the owl tightened its grip the squirrel struggled and hit the snow in several places, touching the snow with its front feet to make the two prints (Sq L and Sq R). Finally the owl’s talons fatally pierced the squirrel and it held the victim on the left side of the hole, causing the bloody spots. The owl then stood on the left side of the hole, shifting its feet slightly as it got a good hold of the squirrel with its beak. It then flew off carrying its meal.

The squirrel’s life ended abruptly, and the owl beat the odds–low on average–of hunting success. Was the old cellar hole, in spite of its suitability for food storage, too exposed for a squirrel to live there safely? Will another small rodent find that spot, take up residence, and maybe even eat the stores still hidden among the rocks? And will that owl revisit the site of its good fortune, hoping for another meal? Sudden death is the way of nature, but it’s also the way of nature for animals to learn from experience and take advantage of every opportunity. I’ll be sure to go by that old cellar hole again to see if it has more stories to tell.

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.