Squirrel Wars

Last autumn, our granddaughter Eva, who was staying with us for several months, started complaining about the noise in the attic above her bedroom.

The squirrel cage in our attic (Photo by Bruce Bonta)

The squirrel cage in our attic (Photo by Bruce Bonta)

At first, I dismissed it as the usual small animal noises on the roof or even in the attic. My bedroom was next to hers and I wasn’t hearing anything out of the ordinary. After all, Eva had lived in town homes all her 22 years and wasn’t used to country life in an old (1871) clapboard farmhouse.

Back in 1971, after we bought our home, we told the contractor who was putting in a second floor bathroom that we were hearing animals in the walls rolling black walnuts.

The contractor, who had worked for the previous owners for decades said, “Oh, that’s the red squirrels. This place has always had them in the walls and attic. That’s why I built the squirrel cage in the attic.”

The squirrel cage is a six foot by 12 foot construction of stiff, fine wire mesh, hardware cloth in which we were instructed to store all items that squirrels might chew on or use as nesting material.

An American red squirrel eating a nut

An American red squirrel eating a nut (Photo by Connormah in Wikipedia, Creative Commons license)

For two years the squirrels continued their lives in our home until my husband Bruce’s parents moved into our guesthouse. I mentioned the squirrels to Pop, and one day, when I came home from shopping, Pop pointed proudly to my clothesline. Hanging by their tails were two dead red squirrels that he had shot. That deed ended the rollicking in our walls and attic, and, in fact, the red squirrel population on our mountain.

Now, more than four decades later, Eva’s complaints continued. Finally, in mid-December, I too began to hear running feet above my ceiling. I wondered if the red squirrel population had recovered but had seen no sign of any in the woods. Then, on a dreary December 29 morning I heard a commotion in the attic. I opened the attic door in my study and saw not a red but an eastern gray squirrel peering down at me. It had used the juniper tree outside my study window as a springboard to the eaves where it had chewed a hole into the attic.

Our caretaker, Troy, repaired the eaves, but he worried that the squirrel might be trapped in the attic, so he set a live animal trap where I had seen the squirrel and baited it with shelled peanuts. The following morning I heard scrabbling in my bedroom ceiling. Troy had caught a squirrel in the trap. Later he released it several miles from our home and re-set the trap.

A gray squirrel at a bird feeder

A gray squirrel at a bird feeder (Photo by Orest Ukrainsky in Flickr, Creative Commons license)

In the meantime, I battled gray squirrels at our three bird feeders hanging from our back porch and on the ground below where they gobbled up most of the birdseed I spread for the birds. Never in all the years we lived here had we had so many squirrels at our feeders. Our dozens of black walnut trees had had few black walnuts, and the acorn crop in our forest had been sparse for the second year in a row.

Meanwhile the squirrel wars continued in the attic. The peanuts were eaten night after night in the trap but no creature was caught. On the morning of January 13 I watched a squirrel climb the juniper tree, stopping occasionally to eat some snow. I alerted Bruce and he saw the squirrel leap on to the roof and come into the attic by way of a new hole it had chewed near the old, patched one.

Troy climbed the ladder to patch the new hole and carefully examined the eaves around the house for new holes but found none. Later, he returned with a trail camera tied to a heavy paint can that he put near the live animal trap. He baited the trap with a plastic cylinder peppered with small holes and filled with shelled peanuts.

At 2:00 a.m. I heard a squirrel run across my bedroom ceiling. The trap was not sprung and the cylinder was gone. I began to think we had Einstein squirrels in residence.

Game cam image of a gray squirrel in an animal trap in our attic

Game cam image of a gray squirrel in an animal trap in our attic (Photo courtesy of Troy and Paula Scott)

That evening Troy came by to check his camera. It looked as if three gray squirrels, one flying squirrel, and a short-tailed shrew had figured out how to get into the trap, grab the capsule and/or previously the peanuts, and escape without springing the trap.

I wasn’t too concerned about the flying squirrel. Apparently, southern flying squirrels sometimes live in attics, “gain[ing] access through windows, crevices under eaves, and similar apertures to the attics of homes,” according to one researcher as quoted in Flying Squirrels: Gliders in the Dark by Nancy Wells-Gosling, p.112. Probably they are the creatures that I do sometimes hear in the attic or walls, but their sounds can’t be compared to the noise of gray squirrels.

A short-tailed shrew

A short-tailed shrew (Photo by Gilles Gonthier in Flickr, Creative Commons license)

The short-tailed shrew, on the other hand, was a puzzle. They do eat plant food, including corn and beechnuts during the winter, and, judging by our attic shrew, shelled peanuts as well. Still these are burrowing animals not known to live in houses, although I once found one in a bucket in our basement.

The weather worsened with cold and snow, and we declared the attic war a stalemate. Troy’s last check of his trail cams showed only one flying squirrel left in the attic. Besides, it was dangerous for Troy to use the ladder, and we hoped his latest eave repair would deter any more destruction by the gray squirrels.

But the squirrel war outside continued. After an eight-inch snowstorm on January 19, followed by minus one degree Fahrenheit the next day, the birds and squirrels were desperate for food especially since ice-covered snow was as deep as a foot in the forest.

From two above zero on January 21, the temperature rose above freezing, and it rained for two days, and then the thermometer dropped to 22 degrees. Our feeders and the ground below was swamped by 15 bird species and at least seven hungry gray squirrels. They were joined in the dawn light by a large cottontail rabbit.

Feeder birds blanketing the snow

Feeder birds blanketing the snow (Photo by John in Flickr, Creative Commons license)

To give more ground-feeding birds a chance against the squirrels, I started throwing birdseed out on the frozen snow on the opposite side of the house near the veranda. This worked for a couple days until the squirrels caught on and managed to dominate both feeding areas. However, on the last day of January it was seven degrees below zero. Birds, especially the white-throated, song, and American tree sparrows and dark-eyed juncos, blanketed the ground below the back porch and on the veranda side, but the squirrels gave up earlier than usual.

The continual snow, rain, and freezing that characterized most of February brought more gray squirrels to the feeding areas. But most returned to their tree nests in the forest every evening. The two most aggressive ones stayed close to the food. One lived beneath our generator near the back porch and the other stayed in the juniper tree even when it was snowing hard. I assumed they were two of the original attic dwellers.

By February 23 we had 11 gray squirrels, and they began attacking our two tube feeders. One squirrel pulled out the plastic guards around the holes of a new red metal feeder I had received at Christmas and ate all the seeds. Never had I had to fight such determined and bold squirrels. Another climbed up our back porch storm door, trying to get inside late one morning while our son Dave was eating in the kitchen.

A relatively squirrel-proof bird feeder hangs on our back porch (Photo by Bruce Bonta)

A relatively squirrel-proof bird feeder hangs on our back porch (Photo by Bruce Bonta)

Finally, the squirrels defeated me, especially the three biggest, boldest pests that never quit for the day, and I removed the tube feeders, leaving only a much larger, relatively squirrel-proof feeder to feed the birds. Still, they mobbed the porch, and when I threw out pounds of mixed seeds for the birds, the squirrels ate most of it.

Our outdoor squirrel war continued even into mid-March, and I acknowledged utter defeat by the 11 squirrels that never left until the snow melted.

On the other hand, we never heard or saw another gray squirrel in the attic so you could say that our squirrel war of 2018-2019 was a draw.

 

Black Squirrels

“Mom, there’s a black squirrel in the flat area.”

A black gray squirrel

A black gray squirrel (Photo by Robert Taylor on Flickr, Creative Commons license)

It was 5:30 p.m. on a balmy day in early March and my son Dave and I were fixing dinner in the kitchen.

I rushed to the window, grabbed my binoculars, and called my husband Bruce to come and see the unusual eastern gray squirrel.

In the meantime, the squirrel had climbed up the back slope and we thought it would come to our bird feeder area below our porch steps. Instead, it veered over to the far edge of my backyard herb garden beside the feeders and ran off. A few minutes later Bruce spotted it below the slope near our old springhouse before it disappeared.

During our 46 years on our mountain we had never seen a black gray squirrel, although I knew there was a population on the Penn State Altoona campus at the base of the Allegheny Front. And later, our caretaker Troy told us he had never seen any black squirrels on our Brush Mountain, the westernmost ridge in the Ridge-and-Valley Province, but he added that there was a population in a small village at the base of our mountain on the Logan Valley side.

The next time I saw the black squirrel, spring had officially arrived even though it was 17 degrees and the ground had frozen hard again. I stepped outside in the early morning and glimpsed the squirrel at the bottom of a backyard black walnut tree. Spotting me, it ran downslope to the flat area and up into the woods on Laurel Ridge.

On April 3, I again glimpsed the black squirrel in the flat area at 7:30 a.m. A gray squirrel, one of the army of 10 raiding our feeders every day, chased it back up into the woods.

Two days later, after returning from my morning walk, I stopped to admire the blooming hyacinths and daffodils in our backyard. That’s when I noticed the black squirrel crossing the flat area. I watched it through my binoculars while it searched for food beneath the leaf cover at the edge of the woods, and paused a couple times to scratch itself.

A gray squirrel approached a black squirrel

A gray squirrel approached a black squirrel (Photo by Eyesplash on Flickr, Creative Commons license)

Once a gray squirrel approached but did not chase it. Nevertheless, the black squirrel retreated but continued foraging. Next it climbed on to fallen trees, using them as runways. Once it sat up on its hindquarters and I saw that it had an orange underbelly. Then it continued slowly on its trek over to the springhouse and wetland where I lost sight of it among the cattails.

Although I continued looking for it throughout the following months, I never saw it again. I figured that a predator had caught it or that it had been visiting and had moved on. But last November one of our archery hunters saw it still living nearby.

Our black squirrel is one of three possible color phases of the eastern gray squirrel.  In Pennsylvania most eastern gray squirrels are gray, but there are also brown-black gray squirrels (our “black” squirrel) and jet black gray squirrels. Canadian researchers, writing in the Journal of Heredity in 2009, studied the color variations in the coat of the eastern gray squirrel by inspecting the hair from all three types under the microscope and found that the eastern gray squirrel “had 6 distinct hair types, compared with 4 from the brown-black and only 1 from the jet black.”

An example of a squirrel with a grizzled coat

An example of a squirrel with a grizzled coat (Photo by Eugenia Vlasova on Flickr, Creative Commons license)

“These different hair types,” they wrote, “give the gray an overall grizzled appearance with a white underbelly, the brown-black an overall dark brown appearance with an orange underbelly, and the jet black a uniform black appearance.”

Or, in the words of Dr. Carolyn Mahan, professor of biology at Penn State Altoona, “The genetic basis of this color phase was researched and determined to be a simple dominant/recessive interaction. Black color is dominant, gray is homozygous recessive, and it sounds like you have a heterozygous individual.”

A brown-black squirrel on the Penn State Altoona campus

A brown-black squirrel on the Penn State Altoona campus (Photo by Dr. Laura Palmer, used with permission)

Mahan adds that the brown/black squirrels have been on the campus at least since 1999 when she began teaching there. She says that, “It is not that they ‘arrived’ there. It is just that the allele [one of a group of genes that occur alternately at a place] for the black color is present in that population. It seems that most of the ‘black’ squirrels are heterozygous for the trait so, if you look at them in bright sunlight, they appear dark dark brown. It seems on our campus there are an equal number of gray and black squirrels.”

Scientific descriptions aside, black gray squirrels are more common farther north while gray squirrels dominate southern areas in the eastern United States and Canada.

Some researchers believe that before Europeans arrived in North America, black gray squirrels were predominant throughout eastern North America because forests were old and thick and provided better cover for that color phase. But once the forests were cut, they hypothesize, gray squirrels became the dominant type throughout their range.

A black gray squirrel in Canada

A black gray squirrel in Canada (Photo by DaPuglet on Flickr, Creative Commons license)

Another, earlier study in Canada in 1978, where black gray squirrels dominate, found that they had “significantly lower heat loss” than gray squirrels during the winter which they thought explained why black gray squirrels were common where winters were colder and there was a constant snow cover despite the fact that a black coat would not provide camouflage for them in a white world.

Native black gray squirrels live in Ontario and Quebec and northern Michigan, Wisconsin, Minnesota and Pennsylvania. But there have been so many releases of these squirrels both in the United States and England, usually courtesy of Ontario, that it is difficult to sort the naturally occurring from the released ones.

In Britain they were released at the end of the 19th century and 18 from Canada arrived at the National Zoo during Teddy Roosevelt’s presidency. Canada also sent 10 to Kent, Ohio in 1961.

The home of the black squirrels, Marysville, Kansas

The home of the black squirrels, Marysville, Kansas (Photo by Jimmy Emerson, DVM, on Flickr, Creative Commons license)

Strangest of all is the so-called “Home of the Black Squirrels” out in the plains in Marysville, Kansas. Supposedly the squirrels escaped from a traveling circus or maybe a gypsy encampment in the late 1920s. Marysville even holds an annual Black Squirrel Celebration.

The black squirrels in Washington, D.C. have spread over the city, and they’ve done the same in other towns and cities where they were released. Apparently, they are safer from their predators, which are primarily birds of prey. And squirrel hunters, eager to bag a black gray squirrel, cannot shoot them in such places.

I checked a couple online sources regarding black gray squirrels in Pennsylvania and compiled a list of cities and towns where black squirrels live such as Fairmont Park in Philadelphia, the Haverford College campus, which has so many that they’ve adopted Black Squirrels as their sports mascot, and the eastern suburbs of Pittsburgh.

A.D. Plummer, who says he hunts and fishes every day in central Pennsylvania, according to the Answers section of the Field and Stream website, claimed he had never seen a black squirrel there until 2009 when he saw two in two places 30 miles apart.

A brown-black squirrel photographed in Goddard Park, Chester County, PA

A brown-black squirrel photographed in Goddard Park, Chester County, PA (Photo by Brian Henderson on Flickr, Creative Commons license)

This provoked several more comments over the next few years. S. Testy, who lives in Enola, Cumberland County, also in central Pennsylvania, wrote in 2009, “There’s a pak of black squirrels that live on Valley Road and North Enola Drive…I’ve seen several out at one time.”

M.J. Frazier in 2012 reported from western Pennsylvania that a small colony nested in their neighborhood and liked bird seeds but stayed away from the gray squirrels.

“The squirrels are solid black and look very kinetic as they move about,” Frazier reported. “They will not come to the feeder close to the house [which probably explains why ‘our’ black squirrel ignored our feeders], but [to] one in the yard about 30 yards away which is stocked with black oil sunflower seeds.”

Rudy Glove, writing in 2015, added “Black squirrels everywhere now.’

Well, not quite everywhere. On the HuntingPA.com website in answer to a hunter’s question about where he can find black squirrels, it looks as if the largest numbers still live in the wild across the northern tier of the commonwealth.

One hunter found black squirrels scattered in five different locations over four counties—Lycoming, Clinton, Potter and Tioga.

Another reported three blacks to one gray in Cook Forest, Clarion County, adding that one day he counted five different black squirrels.

Several were seen near Dubois in Clearfield County and a couple hunters claimed they were common near Kinzua Dam in the Allegheny National Forest. Two hunters mentioned Pike County in northeastern Pennsylvania, and another Brookville in Jefferson County near Treasure Lake.

Whether all these squirrels were coal black, brown-black, or both is not clear except for those reported by M.J. Frazier, but S. Testy does question articles that say only one gray squirrel in 10,000 is black and suspects, at least here in Pennsylvania, that that is a low estimate.

 

April Journal Highlights (2)

Close encounters of the avian kind

April 18. The sun warmed the Far Field, and as I walked Pennyroyal Trail, a towhee sang, a flicker called, and a ruby-crowned kinglet sang. I stopped to “pish,” hoping to entice the kinglet into view, and I did. He flew on to a tree branch, erected his ruby-crown, and sang, giving me my first look at what I had been hearing for weeks.

I went on to the woods beyond the Far Field where a brown-headed cowbird sang and a ruffed grouse crept off into the underbrush. I imagine he was the drummer I stalked back in early April. Sitting still on a moss-covered, old log, I also heard a red-bellied woodpecker, eastern towhee, and northern flicker as the dead leaves rustled in the wind.

The sun quickly disappeared, and I picked my way through the woods until I encountered two excited white-breasted nuthatches on a tree trunk. At first I thought they were courting, but then I realized that they were drinking from sap wells. They were quickly driven off by a male yellow-bellied sapsucker.

As soon as he disappeared higher in the tree, the female nuthatch returned for a few furtive sips. Still, the sapsucker quietly worked on new wells, sipped from old ones, and chased off a ruby-crowned kinglet. Occasionally the male sapsucker flicked his wings as he worked or flew over to an adjacent grapevine as if to rest. Surely there is no tasty sap in a grapevine. The irrestible sap wells are on a pignut hickory, as usual, and it is encircled up its trunk with old sap wells.

The nuthatches returned, calling softly, as they drank from the lower sap wells while the sapsucker worked high in the tree drilling new ones. At last I left the relatively peaceful scene, two species sharing one resource.

April 20. I used my turkey call as I sat in the spruce grove and called in a hen turkey. She came close to my hiding place at the edge of the grove and then retreated back to the edge of the woods along First Field Trail, clucking all the way. I’ve never called in a hen before, but according to one of our turkey hunters, that’s not unusual. Still, experts disagree on why they respond to a hen call. Is she already setting on eggs and defending her territory? Is she a scout for a male turkey or trying to keep rivals from joining “her” gobbler? Is she recruiting more hens for “her” gobbler? Is she merely curious? Are there reasons that we can’t even imagine?

Then, walking back on the Far Field Road, I scared up a gobbler. He, of course, saw me and ran, but I did get a quick look at his long beard. Was he still searching for hens? If only I had tried the hen call along the road. Oh well! It’s obvious that the turkeys are restless and have perhaps not gotten together yet due to the cold.

Above the barn on Butterfly Loop at dusk, the woodcock called, turning around to direct his call in all directions as we watched from a respectable distance.


Gray squirrels and masked shrews: social behavior

April 21. At least three young gray squirrels were born in the black walnut tree nest hole beside the driveway. Today they emerged for the first time, or at least two of the three did. I sat watching on the veranda as first one emerged and stayed out, exploring nearby branches. Then the second emerged more briefly and stayed closer to the nest hole before going back into it again. Each squirrel chewed about the hole entrance, hanging upside down before emerging. When both squirrels were out, a third one peered timidly out of the hole, but stayed inside. All their climbing about, peering in and out of the hole, even their chewing was silent. But scolding from a distant adult squirrel sent them all back into the den hole with one looking out. Three adults harvested black walnuts on the lower lawn.

The first six-spotted tiger beetle gleamed bright green on the driveway.

April 23. The gray squirrel family, even the shy one, played in, out, and around their nest hole as we watched from the veranda.

April 24. I heard a black-throated green warbler in the woods near the powerline right-of-way singing both his songs. As I stood listening and watching, a masked shrew dashed in and out of the leaf duff along an old, barkless, fallen tree. I sat quietly, watching for the shrews, and heard the first blue-gray gnatcatcher of the season. As I continued on the trail, a pair of mallards flew past on the powerline right-of-way, heading toward the First Field. Were they the same mallards Dave saw earlier in the morning? Had they gone back to Sinking Valley? Who knows? But at least I saw them.

More masked shrews chased in the woods on the other side of the powerline right-of-way. They crossed right in front of me for several minutes so I sat down on the trail and watched as they dashed back and forth across the trail, always using the same pathway at my feet. They were tiny, grayish-brown, with peculiarly-shaped snouts that identified them as masked shrews. I counted half a dozen or more chasing about. They were silent to my ears except for the rustling in the leaves. The books say that they are looking for food, but I only see this phenomenon in April and sometimes in July and I think it has to do with mate-chasing. None of the books say anything about their sex life. I suspect they have two broods a year, but I can’t prove it. Finally they stopped and I continued my walk.

The return of the wood thrush

April 27. Sitting on the veranda reading near dusk, we heard the first whip-poor-will of the season singing above the garage at dusk.

April 28. A pair of northern flickers checked out the black walnut tree squirrel den. Were they waiting until the young gray squirrels leave so they could take over the nest hole?

April 29. I stepped outside early to listen for the wood thrush, but the towhees were so loud they blocked out more distant sounds. Still, I did hear a faint portion of a wood thrush song. I stopped and gave thanks that another spring had come and with it wood thrush music–three months of heavenly singing before they once again leave us.

On Dogwood Knoll a rose-breasted grosbeak sang. And then, as I descended the knoll on a path of blooming dwarf cinquefoil, I heard the singing of a Louisiana waterthrush above the dark place. Halleleujah! We have at least one singing male. I sat on Turkey Bench to listen to his ringing tones.

Down near the bottom of the mountain I heard the “tick-tick” scolding tones of another Louisiana waterthrush. I rested on a moss-covered log beside the stream, still hearing but not seeing the waterthrush.

Bruce came down the road and a small, black, white and orange moth spun around his hat and landed briefly on it. Then it landed on my hat and Bruce photographed it. It was a grapevine epimenis, Psychomorpha epimenis — an early, day-flying moth whose caterpillar feeds on grapes. Truly a beautiful little creature.

In mid-afternoon, Steve pointed out a black vulture sailing over First Field.

April 30. At breakfast I watched a northern flicker throwing to the wind the remains of the squirrel nest in the walnut tree. Those flickers had been checking on the den every day, evidently waiting until the squirrel family dispersed.

Walking up Guesthouse Trail, I finally heard the wood thrush singing clearly. Wild black cherry and striped maple trees have leaved out and already my view into the woods has diminished.
__________

See also my post at the Plummer’s Hollow blog, Spring wildflowers: back on track.

Nature’s Ultimate Bankers

It’s late January as I crunch over frosty, fallen leaves on my way to Coyote Bench. Almost immediately I hear the high-pitched whine of a female gray squirrel in a mating chase. Four male squirrels are after her, but one male fends off the others. Once the female turns and faces him at the end of a branch and he retreats. Then she enters a tree cavity and pokes her head out, nipping at any male squirrels that try to enter.

Her actions are designed to send the males into a greater frenzy and they do. A dominant male busily defends the cavity from above and below while the other males try to breach his defense. When he drives away all but one other competitor, she emerges and races off in what scientists call a “breakaway.”

A Johnny-come-lately runs up the tree she had been in, following his nose and emitting the low, grunting calls of a questing male. He sniffs around the rim of the cavity, thrusts his head inside, and then runs back down the tree trunk.

At this point, the female, pursued by five males, streaks up from the ravine and across the road. The last I see of her she has six males on her tail.

According to an excellent new book North American Tree Squirrels by Michael A. Steele and John L. Koprowski, this courtship day started shortly after dawn and will continue for eight hours. In that time the female will probably mate three or four times with two to four males.

Although female squirrels are only receptive to mating for about eight hours, males are active from November until August. Every day during that period, they spend the first couple hours visiting the nests and home ranges of adult females. Cautiously they sniff the rear ends of each female they encounter. If they find one within five days of her receptive period, they follow her. By the big day, males have congregated outside the female’s nest from as far away as half a mile. Although P.D. Goodrun watched a record 34 Texan gray squirrels in a mating bout back in 1961, Steele and Koprowski have observed up to 22 and my personal record is 10.

If the food sources are good, female squirrels may mate twice a year, according to Michael A. Steele, who is an associate professor of biology at Wilkes College. During a telephone interview, Steele told me that Koprowski wrote the chapters on social behavior and reproduction and he wrote those on habitat, diet, patch use, food caching, and seed dispersal.

Steele has several northeastern Pennsylvania forest sites where he conducts his extensive research on food selection, habitat use, and seed production by small mammals, but one of his favorite and most visible sites is Kirby Park along the Susquehanna River in Wilkes-Barre.

“We get a lot of questions from visitors,” Steele says. And no wonder. Does anyone in Wilkes-Barre recall seeing people vacuuming up the remains of acorns in Kirby Park? As part of a study Steele and his students conducted of the caching and feeding behavior of gray squirrels in autumn and winter, they used a handheld, portable vacuum to collect pieces of acorns that gray squirrels dropped after they ate, Steele writes in North American Tree Squirrels. They needed all those pieces to figure out why squirrels seemed to eat less efficiently in winter, when they needed the extra energy to survive the colder temperatures, than in autumn. What they found was that early in autumn, they feed quickly and sloppily, dropping edible portions of the acorns, and in winter they eat slowly and carefully and drop very few, if any, small, edible pieces. They concluded that in autumn they eat quickly so they can cache as much food as possible when it is abundant and in winter they spend more time eating every bit of the acorn and carefully storing whatever other nuts they can find.

This is just one of many studies Steele has performed on the habituated gray squirrels of Kirby Park. “Tree squirrels,” he and Koprowski write, “are model organisms for testing and exploring important questions in behavior and ecology.” So Steele live-traps them and uses dye to mark all the gray squirrels in the park with letters or numbers. Over the years, people have asked him and his students why they bother to study such common, well-known animals.

“They don’t realize that many of the experiments done at this park have become famous,” [in scientific circles], Steele says. Furthermore he maintains, “How little we really know about the world around us. These are critters we see every day,” and yet they engage in complex behavior still not fully understood by ecologists.

One of Steele’s newest studies in the park asks why squirrels bury smaller acorns close together and under the canopy and larger acorns farther apart and beyond the canopy. After all, squirrels risk predation by hawks and use more energy to bury the larger acorns. However, those acorns are less likely to be pilfered by other squirrels and chipmunks. The smaller acorns, which are not as desirable, are more easily discovered and dug up by other animals. Those animals keep a constant watch on each other and where they bury their stores.

But Steele has also found that gray squirrels are “masters of deception.” They frequently dig a hole, pretend to bury a nut, and cover it over. Then they move on and bury a nut somewhere else. This “functional deception,” as Steele calls it, “really confuses onlookers, such as chipmunks, blue jays, and other squirrels, as to where they’ve buried the nut.” They may pretend to bury an acorn anywhere from two to nine times before actually doing so. Sometimes they reverse this procedure by immediately burying an acorn and then pretending they are burying it somewhere else.

Tree squirrels, Steele hypothesizes, may be “nature’s ultimate bankers…moving and managing caches, much the way a financier will manipulate investments to maximize long-term returns…”

And the way they bury acorns helps to decide the future of oak forests. Steele and his colleague Peter D. Smallwood of the University of Richmond have been performing a series of studies to find out why eastern gray squirrels, flying squirrels, deer mice, white-footed mice, and fox squirrels usually store acorns from the red oak group and eat those of the white oak group. It turns out that the gray squirrels, at least, know that white oak acorns will germinate almost immediately and red oak acorns will not germinate until the following spring. If they do store white oak acorns, they first bite off their tips, which destroys the embryo and prevents them from germinating.

But how do they “know” this? “Likely there is a chemical cue in the shell of the acorns that tells squirrels to store red oak acorns,” Steele says, because after soaking the shells of both red and white oak acorns in acetone, which masked the difference between the species, the squirrels ate all the acorns. In Pennsylvania there are three times as many red oaks as white oaks. Could the way gray squirrels bury acorns have something to do with this? On average, Steele and Smallwood have discovered, the squirrels cache 15% of white oak acorns, usually near the acorns’ parent trees, and more widely cache 60% of red oak acorns. To do this, gray squirrels “scatterhoard,” meaning that they bury only a few or one item in many dispersed cache sites instead of storing all their food in one place as larderhoarders, such as chipmunks and red squirrels, do. Lately, Steele has been putting metal tags on individual acorns and then finding out later where they have been cached.

Such scatterhoarding does increase the chances that acorns may germinate on years when there is a bumper crop of nuts. This so-called “predation satiation hypothesis” speculates that trees “evolved to satiate seed consumers in food mast years and cull their population in poor years.” Unless they are overwhelmed by a crop, die, or disperse from their caching area, squirrels recover as many as 95% of their cached acorns because they are able to remember their exact locations. So far, scientists do not know how long they remember.

Tree squirrels appear to be important seed dispersers. “By transporting and scatterhoarding acorns…to individual sites just below the leaf litter, many tree squirrels reduce the probability of seed predation, seed desiccation, and seedling competition, and at the same time increase the chances of germination, root establishment, and winter survival…The cache sites of…the eastern gray squirrel may even be optimal for germination, survival, and growth of oak seedlings,” Steele writes.

Both Steele and Koprowski have studied tree squirrels for more than 20 years, but they make it clear that many questions about tree squirrels are still unanswered and that there is still much more that can be learned about their behavior and its effect on our forests. And because they are easy to observe, they are ideal mammals to study.

After reading North American Tree Squirrels and talking with Steele, I am more interested than ever in watching the behavior of gray squirrels. This is exactly the reaction Steele and Koprowski are hoping for from all the folks who read their book. “A little time with this book, and the reader should never view a squirrel in quite the same way again,” they write in their preface. “For the general reader, we seek to share not only our knowledge of the tree squirrels but also the sheer delight that comes with studying them…”

They have succeeded admirably.