Chickarees

red squirrel with nut

photo by Franco Folini (Wikimedia/Creative Commons)

When we moved into our 100-year-old, Pennsylvania farmhouse back in 1971, red squirrels lived in the attic. They ran over the attic floor and between the walls at all hours of the day and night. Tired of being awakened by their rambunctious noises, I asked the local contractor, who was doing some work on our house, about keeping out the squirrels.

“They’ve always lived there,” he said.

Clearly, he had no intention of doing anything about them.

Two years later, my in-laws sold their home in New Jersey and moved here to live in our guesthouse during the warmer months. One morning I complained to my father-in-law about the squirrels.

“Don’t worry,” he said. “I’ll take care of them.”

I thought he planned to get a live trap for them. But one day, when I returned from shopping, two dead red squirrels were pinned to my clothesline by their tails. Pop was so proud he hadn’t lost his prowess as a small game hunter that I hadn’t the heart to object. I also couldn’t believe only two red squirrels had caused the commotion in the attic.

Having moved from Maine, where we had lived in the country for five years and hiked in our mixed conifer woods filled with scolding red squirrels, I had no idea that central Pennsylvania had marginal habitat for them. But over our 41 years here, after the two attic squirrels were eliminated, I had had only a couple other brief sightings of a red squirrel.

Then, last October 16, our caretaker wife, Paula Scott, and our son Dave’s English girlfriend, Rachel Rawlins, sat in a camouflage tent blind at the edge of a small patch of woods between our overgrown garden site, and the powerline right-of-way. Paula was showing Rachel how she hunted for deer during archery season.

They never did see any deer, but Rachel came back excited about the red squirrel they had watched.

“Red squirrel,” I asked. “Are you sure?”

American red squirrel eating a nut

photo by Connormah (Wikimedia/Creative Commons)

They described the red squirrel perfectly. It was half the size of a gray squirrel and had a dark red head, back and tail, white underside, and white eye ring. Also known as a “chickaree,” “pine squirrel,” “fairy diddle,” “chatterbox,” “boomer,” “rusty squirrel,” “barking squirrel,” or “Bang’s red squirrel,” its scientific name is Tamiasciurus, meaning “steward,” hudsonicus, for Hudson Bay, the site where its type specimen was found.

“Pine squirrel” refers to its preferred habitat—boreal coniferous forest with an interlocking canopy that provides protection for tree nests as well as its preferred food of conifer seeds and fungi, which can be preserved in the cool, moist environment. “Rusty squirrel” and “Bang’s red squirrel” describes its color, but all the other names refer to its repertoire of calls, specifically the alarm call “chirp” when predators are near and the threat call “rattle” in defense of their territory. With the “rattle” they may use a screech call or growl, and when approaching a female that may growl at them, a male will emit a buzz call.

But the red squirrel the women watched had been silent. And those few I had seen over the years also had been quiet. That’s because, when there are only one or two of them in widely spaced territories, they have no need to defend their turf.

Needless to say, I was sorry not to have been in the blind and seen the red squirrel. Eight days later, though, on a lovely October morning, I walked down First Field and paused to watch a white-crowned sparrow sitting on a weed head near the small patch of “red squirrel” woods.

That’s when I noticed a movement near Paula’s blind. I remained still, and the red squirrel climbed to a low tree branch and sat there while I watched it for several minutes before it dashed down the tree trunk and disappeared.

My next and, as it turned out, my last sighting of the red squirrel was on a warm December 4. Walking past the “red squirrel” woods, I noticed something atop an uprooted tree mound. It was the red squirrel, sitting up, its little paws folded across its chest. Whether it was worried about me or the gray squirrel running from First Field into the woods, it remained still and silent. Finally, I continued on my walk.

It was 13-year-old Carl Engstrom, who came up to participate in our Christmas Bird Count on December 16, 2012, who was the last person to see the red squirrel. He looked out our bow window and glimpsed the squirrel down the back slope. I was making lunch in the kitchen, and by the time I ran to the window, it was gone.

Unfortunately, a muscle tear kept me inside for most of the winter and while I watched our feeder area that was mobbed with gray squirrels from far and near because of a mast failure, I never saw the red squirrel there, although Carl’s mother, Dr. Carolyn Mahan, a squirrel expert at Penn State/Altoona, says that red squirrels rarely use bird feeders. They also eat such a wide variety of food that she doubts that it starved. In fact, she thinks it may have been attracted by black walnut trees at the edge of the grove, which had produced nuts.

American red squirrel in winter with peanut

photo by Gilles Gonthier (Wikimedia/Creative Commons)

Red squirrels are opportunistic creatures, and even though they may prefer the food in boreal coniferous forests, they will eat acorns, beechnuts, hickory nuts, hemlock cones, tulip and sycamore seeds, buds of maple and elm trees, sumac fruits, fungi, insects, and an occasional nestling or clutch of birds’ eggs, all of which we have somewhere on our mountain except for the sycamores.

They also “tap” sugar maple trees in late winter for their sap by biting into the xylem of the trees and coming back to those taps after the sap has dried, when the sap has gone from two percent sugar to 55 percent, and licking the maple sugar.

They store whatever food they collect in late summer and autumn in middens or caches that may be in a hollow tree or burrow. Occasionally, they scatter hoard and sometimes they bury food in wet places where it may stay fresh for several years. Fungi are either dried in trees or in middens along with nuts, hawthorn and sumac fruits.

I never did find a midden in the couple hollow trees on the ground, although in a study Mahan and Richard Yahner did nearby back in the early 1990s, they found that red squirrels used burrows on nine occasions. They hypothesized that if the area had a high percentage of herbaceous vegetation which concealed burrow systems, those systems could serve as places of refuge or nesting sites for red squirrels in marginal habitat where the interlocking canopy of trees for safe leaf nesting doesn’t exist. Certainly, I saw no sign of leaf nests in the “red squirrel” woods.

Whether it starved or was killed by a predator, we’ll never know. But most of the long list of predators that eat red squirrels—fishers, bobcats, large hawks and owls, coyotes, crows, weasels, martens, gray and red foxes—live on our mountain.

Where it came from is another mystery. But Mahan suggests it could have dispersed a distance from its birthplace using our wide corridor of mountaintop forest.

mother red squirrel with two of her young

mother squirrel with two of her young by Gilles Gonthier (Flickr/Creative Commons)

Red squirrels come into heat for one day in late winter and again, in early summer. Only then does the female allow males to enter her territory, which she defends year round, to mate. She may mate with as many as four to 16 males in that day after mating chases. She then settles into one of several nests, in her half to three-acre territory. Made of grasses, mosses, shredded bark and leaves, she may construct it in a deserted woodpecker hole or natural tree cavity in hickories or oaks, a rock pile, hollow fallen tree, or burrow.

After 35 days, she bears three to seven pink and hairless young. Their ears open at 18 days and their eyes at 21-35 days. In 40 days their pelages are fully developed. When they are six to eight weeks old, she weans them.

As they grow, the litter mates chase and mock fight. A few weeks after weaning they are on their own and in search of their own territory. Even when, in 15 percent of litters, a mother gives up a portion or all of her territory to her young, a process known as “bequeathal,” only 22 percent of all young red squirrels survive to breed at one year of age.

I assume our red squirrel had been born in August and had recently dispersed. Or perhaps, it was an April birth. In any case, it did not survive to start a family of its own. After so many years without red squirrels, I was pleased to see one nearby. But not, thankfully, in our attic!

American red squirrel swimming

swimming red squirrel by Lindsay Trostle (Wikimedia/Creative Commons)

The Value of Aging Trees

A big red oak on top of Sapsucker Ridge

A big red oak on top of Sapsucker Ridge

On a hot July day, I sit beneath a large red oak, nestled into a deep buttress, one of several that flare out from this 200-year-old tree. The ground beneath the tree is littered with old acorn remnants as are the bases of the other elders in this stand of deciduous trees.

Protected as a picnic spot by the previous owners, the trees were allowed to prosper even as other portions of our property were cut over in the nineteenth and even twentieth centuries. Instead of fencing a young forest, such as that last 120-acre cutover piece we acquired back in the 1990s, we put up our three-acre deer exclosure in March 2001 around these mature trees.

Now, as I gaze around, I see dozens of oak seedlings and saplings filling in the forest floor. Most are red oaks, but some are offspring of the enormous white oak beside the exclosure gate.

Technically, this is not an old-growth forest but one that is becoming old-growth. Still, it and much of the rest of our property consists of an aging forest. Not long ago, old trees were seen as useless and were harvested so that young trees would grow in their place. But in the last few decades scientists have been discovering that old trees in an old forest are incredible absorbers of carbon dioxide. And red oaks, with their dense wood, are particularly good at absorbing impressive amounts of carbon.

One study, in Massachusetts’s Harvard Forest, found that at 50 years of age, their trees, both oak and maple, were absorbing 0.8 tons of carbon per acre every year. After 15 years, the rate of carbon uptake had doubled. Researchers studying old-growth forests in the West discovered that those forests too absorbed more carbon as they aged.

One of those researchers, Bev Law, of Oregon State University, told a journalist that, “Across forest types, globally, we find that the amount of carbon stored is high in older forests, and that live carbon continues to accumulate for centuries.” This carbon is held not only in the trees themselves but in their fallen leaves and branches as well as in the fertile soil of old forests.

Law is director of the AmeriFlux Network, an international collaborative project founded in 1996 to measure the carbon dioxide, water vapor, and energy in all kinds of major ecological community types or biomes in North, Central, and South America. Using a variety of sophisticated tools, scientists are able to track carbon in any ecosystem. Here in our eastern forests, studies have been done in several states including the aforementioned Massachusetts.

Old trees in an old forest have other uses too. They provide large hollow trees for a variety of birds and animals that use them for nesting, food, and shelter. For instance, sycamore trees are the most massive trees in the eastern United States. They can grow over 100 feet tall and 10 feet wide and live up to 500 years. When they are very old, they have a cavity at ground level large enough, in one recent case, to house a maternity colony of 100 Indiana bats, researchers discovered back in 1993.

A giant eastern hemlock tree in Central Pennsylvania

A giant eastern hemlock tree in Central Pennsylvania

Large, hollow trees also appeal to children of a certain age. I was reminded of Jean Craighead George’s book My Side of the Mountain which my husband Bruce read aloud to all of us when our three sons were young. They were all entranced by the 12-year-old hero of the story, Sam Gribley’s large, hollow tree home in the wilds of the Catskill Mountains. In his case it was a hemlock tree. Remembering the many old-growth hemlocks we have (or had, before the hemlock woolly adelgids killed so many of them in our Pennsylvania old-growth forests), I knew that such trees might have been large enough to house one young boy.

Because our old-growth hemlock trees are mostly in Pennsylvania’s state natural areas, the trees attacked by adelgids have been allowed to die and be reclaimed by the earth as our son, Dave discovered during a recent visit to Snyder-Middleswarth Natural Area. Many people find this wasteful, believing that such trees should be harvested. But Dr. Joan Maloof, who has been writing and speaking about the value of old-growth forests, maintains that “old-growth forests are one of the few land uses where topsoil is created instead of destroyed.”

We like to think that our own younger but mature forest is also creating soil as we allow our trees to fall over and rot, creating, as our young nephew Patrick once cried over and over, “Dirt, dirt, dirt” while sifting the powdery, reddish-brown remains of red oak branches through his fingers. Those powdery remains of the heartwood and sapwood appear to be a nursery for the downy rattlesnake plantains I’ve discovered inside and outside our exclosure. When we first put up the exclosure, I found a large colony of this orchid growing on a slope where several trees had rotted down to heartwood and sapwood. Another plant that we found outside the exclosure and fenced had germinated beneath a stump that was seeping rotted wood at its base.

Then, a couple years ago, I found still another downy rattlesnake plantain plant that had germinated on the decaying remains of a fallen red oak limb. At the same time, I noticed that the fenced plant outside the exclosure was looking poorly. I gathered up more of the “natural” fertilizer from the trunk and sprinkled it over the plant, and once again it is thriving. I haven’t seen any studies that indicate that downy rattlesnake plantain needs this material, but I wonder.

Photographing downy rattlesnake plantain in our deer exclosure

Photographing downy rattlesnake plantain in our deer exclosure

As our forest has aged over the last 41 years we’ve lived here and now nearing one hundred years of age in our hollow area, our forest bird diversity has increased. Fallen trees across our first-order, headwater stream, attract several breeding Louisiana waterthrushes and winter wrens. Barred owls court and nest in our larger, hollow trees. Scarlet tanagers, worm-eating warblers, and red-eyed vireos, among others, are more common than ever. Once we had no nesting black-throated green warblers, cerulean warblers, blue-headed vireos, winter wrens, or Acadian flycatchers, but our aging forest has attracted them. All of these bird species and several more, such as blackburnian warblers — depending on whether species need coniferous, deciduous or mixed deciduous forests — use older, mature forests. And the larger these forests are, the better the chances are for the birds to fledge nestlings.

The same is true for many mammal species. Bears, raccoons, and porcupines, for example, like to den in large, hollow trees. One study of black bear den trees found that in order for red and white oak trees to be big enough, they had to be between 175 and 280 years old, which reminds me of the huge oaks our boys found more than 30 years ago at the steep base of our mountain on a property line with a neighbor. They took some box camera photos of themselves standing in front of them and they looked as if they were as large as California redwood trees. I was amazed and delighted, but before I had a chance to see those trees, our neighbor’s logging operation had cut them down. The boys went to check on them and said that they were all hollow inside, so excellent habitat had been destroyed and not a dollar earned on those trees.

The same den tree study found that raccoons liked tree hollows in trees from 90 to 164 years old, and gray squirrels 65 to 130 years in age. Many bat species, too, like old trees with cavities and loose bark. Other opportunities for denning in older forests include in soil pits created by large root masses of wind-tilted trees, in the root masses themselves, and in stumps, logs, large, horizontal limbs and cavities in standing trees, all of which we have in abundance in our aging forest..

One special kind of older forest that has diminished greatly is that of mixed red spruce and hemlock in the northern tier of Pennsylvania. Such a forest especially appeals to red-backed voles, water shrews, and state-endangered northern flying squirrels. According to researcher Dr. Carolyn Mahan of Penn State, this type of coniferous forest creates a moist microclimate that supports a diversity of fungi, which both the voles and the northern flying squirrels thrive on. They also spread the fungi spores, thereby enriching the soil. Water shrews also seem to prefer such forests, but they like them to be in swampy ravines.

Megalodacne heros beetles feed and mate on varnish shelf fungi, found on an ancient hemlock logs

Megalodacne heros beetles feed and mate on varnish shelf fungi, found on ancient hemlock logs

We also have red-backed voles in our deciduous forest, and Mahan explains that they are not specific to old red spruce/hemlock forests, but more of them are found there than in forests such as ours. Northern flying squirrels are much rarer in our state because they are habitat specialists and their red spruce/hemlock forests have been lost to habitat fragmentation from development of all kinds and to hemlock woolly adelgids. The remaining smaller, patchier coniferous groves next to deciduous forests also attract the more generalist and numerous southern flying squirrels. They are sharing nest sites and even hybridizing with northern flying squirrels, and in the process, passing on a roundworm species, Strongyloides robustus, to which they seem to be immune but which is killing the northern flying squirrels.

Mahan has 600 nest boxes in 21 study sites for the northern flying squirrel, and this year not one northern flying squirrel has been found in any of those boxes. Last year she and other researchers planted an experimental 2500 native red spruce seedlings among the dying hemlocks of a site and others in a recent Game Commission clearcut which was fenced to see if they will grow and thrive and someday produce more red spruce forests. If they do well, they will plant more red spruce seedlings. But think how long it will be before there will be another red spruce forest as magnificent of those we had in Pennsylvania. How much better it would have been if we had saved larger pieces of our older spruce forests.

After talking to Mahan and other researchers, I am more determined than ever to keep growing an older forest. But on this hot summer day, I most appreciate our mature forest for its deep shade that cools not only me but all the creatures large and small that live here.

All photos by Dave Bonta ~ click on images to view larger versions at Flickr