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.
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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.

Furry Raiders

I knew there was going to be trouble last autumn when the acorn, black walnut, beechnut and hickory crops failed. Our mountain then supported the largest population of eastern gray squirrels in the 26 years we have lived here. Every acre of forest contained leafy squirrel nests tucked high in the tallest deciduous trees. And by December I was spending a couple hours every day defending my bird feeders from a horde of the furry creatures. Sometime in the middle of the month I reached a high of 15 gray squirrels. But by mid-March their numbers had dwindled to five.

Woodland gray squirrels are shy creatures that prefer to eat wild foods when they are available. Their favorites are hickory nuts followed by hazelnuts and white oak acorns, although pecans in the south and black walnuts in the north are also popular. Nut-bearing trees have irregular fruiting periods to prevent nut-eating creatures from building up huge populations capable of eating every nut a tree produces. After a particularly good nut-bearing year, the trees’ exhaust their supply of stored carbohydrates, which are needed to produce a nut crop so they skip a year.

But the nut predators, such as gray squirrels, have increased because of the previous abundance of food. When the nut crop crashes, so too does the squirrel population. Since most mature deciduous forests have a wide variety of nut-bearing trees, it is rare that they all fail at once. Here on our mountain it has happened five times in 26 years. At such times squirrel die-off can be severe.

One of the worse die-offs occurred between 1953 and 1954 when 95 per cent of the squirrels perished in suburban Maryland because of an acorn shortage. In those days bird-feeding was not the popular hobby it is today, so there was no artificial food to help the critters out.

Malnutrition is the greatest killer of squirrels. Either they die outright from starvation or their weakened condition leads to diseases such as sarcoptic mange. Caused by scabies mites, underfed squirrels lose their fur, a deadly condition in winter when squirrels depend on an outer layer of fur, an underfur for more insulation and skin protection, and a layer of fat to keep warm.

Another strategy males and immature females use to conserve body heat in winter is to sleep together in a drey (nest). The winter dreys are constructed to last. Both sexes build them using twigs on the outside and moss, lichen, fur, feathers and leaves on the inside. They are waterproof and strong enough to survive heavy winds. But tree cavities are preferred den sites especially in colder climates.

In both dreys and tree dens squirrels sleep much of the winter, especially during severe weather when they don’t come out at all. But on reasonably good days they invaded my feeders early in the morning and late in the afternoon, the usual foraging hours for wild squirrels.

Ideally each gray squirrel eats one and a half pounds of nuts every week or an average of three ounces at each feeding. Unlike red squirrels, gray squirrels do not defend territories or their buried nut supply. Their one to seven-acre ranges are shared so that whatever one squirrel buries is fair game for its fellow range inhabitants to sniff out, dig up and eat. However, researcher Michael Steele of Wilkes College in Wilkes-Barre has watched gray squirrels pretend to bury nuts at several places before finally doing so, a strategy they may be using to confuse other cache robbers such as chipmunks and blue jays.

At bird feeders, gray squirrels prefer black oil sunflower seeds. But while they eat enormous amounts during famine years, they ignore our feeders in feast years. This would not be the case with city and suburban squirrels. They have no preference for wild nuts and will eat whatever humans offer them including a wide variety of junk food. Some have even learned how to steal candy and nuts from vending machines.

“In Pittsburgh’s Schenley Park…” writes Eugene Kinkead in his hugely entertaining and informative Squirrel Book, one [gray squirrel] was seen regularly to reach a forepaw up into the back of an outdoor vending machine, pull out a candy bar, and run away and eat it.” However, he did show his squirrel inheritance by preferring bars with nuts.

Park and suburban squirrels are active all day long and, unlike their wild relatives, have few predators except for feral cats and cars. Consequently, they are bold and fearless toward humans. Because most parks and suburban areas don’t have enough habitat to support squirrels, especially through the long winter months, people who feed birds spend a good bit of time, energy and money attempting to thwart squirrels.

Reading about the exploits of such squirrels, I am almost ashamed of our wild squirrels. They obligingly run when I chase them and don’t even try to tear apart my square tube feeder encased in heavy wire mesh. Called the “squirrel’s dilemma” feeder by Bill Adler, Jr., author of the bestseller Outwitting Squirrels, Adler claims that even with a baffle attached (which mine doesn’t have), it takes savvy city squirrels 90 seconds to figure out how to feed from it by hanging upside down at the openings. Not only have my squirrels ignored this feeder, but they are easily chased from my wooden, barn-shaped, hanging feeder with the sides removed. This feeder Adler dismisses as a “squirrel attractor.”

One feeder that is safe from squirrels is a thistle feeder. But that’s only because squirrels don’t like thistles. Sunflower seeds, on the other hand, “bring in squirrels like an insider stock tip brings in stock brokers,” Adler says.

Furthermore, I was pleased to learn that “birdfeeding and squirrel yelling are common practices.” Of the “101 Cunning Stratagems to Reduce Dramatically the Egregious Misappropriations of Seed from Your Birdfeeder by Squirrels” (the somewhat cumbersome subtitle of Adler’s book), Number 30–“Run outside yelling and waving your arms every time a squirrel appears”–is one of the few that is practical. As Adler says, “Not only will you scare squirrels away, but you’ll get terrific exercise.” During long, sedentary winter days my husband Bruce and I take this advice to heart. Bruce has even perfected a terrifying call that scatters the squirrels in all directions.

Most people have either a love or hate relationship with squirrels. Dick E. Bird of Dick E. Bird News claims that, “there isn’t anything that’s going to keep squirrels away. My philosophy is to feed squirrels and birds and enjoy.” He has a separate feeder for squirrels that holds acorns and other wild nuts that he’s gathered. According to Bird, the squirrels go crazy over the food he provides.

A correspondent in Wild Bird News also defended squirrels at feeders. “The only reason they get in the bird feeders is that they are hungry,” she wrote. “In the fall of 1987 there were not many acorns. We have cut down so many trees that squirrels depend on us for food.”

One man was so worried about the fate of urbanized squirrels and birds that he left his entire $90,000 estate for an endowment to feed birds and squirrels in Fargo-Moorhead, North Dakota. And Gregg Bassett of Elmhurst, Illinois started The Squirrel Lover’s Club in August of 1995. Less than three years later it had 600 members from 37 states and six foreign countries.

In 1984 Lafayette Park in Washington, D.C. held more squirrels (120 in an eight-acre park) than any place on earth because tourists and residents fed them every day. One resident spent between sixty and ninety dollars a week on nuts for squirrels.

Washington also has the dubious honor of having had seven squirrel-caused power outages in one day because squirrels frequently use electrical transformers at the top of power poles to bury their nuts and are zapped.

Furthermore, D.C. squirrels are unusually smart. A spring-loaded door on a metal feeder designed to foil squirrels was quickly opened by a pair of D.C. squirrels that “suspended themselves spread eagle across the top of the feeder with one paw free to reach down, exert pressure, and help themselves to feed,” Adler says.

Not even the fearsome numbers of Lafayette Park squirrels match the historical record of abundant squirrels. In 1749 the colony of Pennsylvania put a three pence bounty on each squirrel scalp. That year 640,000 squirrels were killed. In those days squirrels used to migrate in hordes as feared as a flight of locusts. John Bachman, naturalist, minister and good friend of John James Audubon, reported from Charleston, South Carolina about one such migration. “Onward they come, devouring on the way everything that is suited to their taste, laying waste the corn and wheatfields of the farmer . . . “

In 1842 a migration left Wisconsin and headed southwest. Lasting four weeks, it was 130 miles wide and 150 miles long. Observers estimated that it contained half a billion squirrels.

The last large migration occurred in 1968 when approximately 20 million squirrels were on the move from Vermont to Georgia. Biologists believe such migrations are a way for squirrels to disperse their population since they always happen in the fall, particularly September, when numbers are high.

Of course such bounty, while cursed by farmers, was appreciated by hunters and settlers who relished squirrel meat. But no matter how many were killed, more filled in the ranks almost immediately. Squirrel hunters, armed with long-barreled Kentucky squirrel rifles, were excellent marksmen and feared opponents during the American Revolutionary War, the War of 1812, and the Civil War. In fact, during the Civil War, the Confederates decided not to attack Ohio when they learned that 50,000 squirrel hunters had volunteered to defend the state.

Many historical figures were squirrel lovers, even Ben Franklin who went to a great deal of effort to send one as a pet to a little girl in England. When it was accidentally killed by a dog, the little girl wrote to Franklin and asked him to compose an epitaph for her squirrel, or “skugg,” as the British called them. He wrote two. One was properly long and dignified. The other was short and gave us an expression that we still use.

“Here Skugg

Lies snug

As a bug

In a rug.”

Whenever any magazine dares to have a squirrel article in it, squirrel lovers and haters line up to be counted. Eugene Kinkead first started his squirrel research when writing an article for The New Yorker back in the seventies. He received so much correspondence about it that he wrote a second article that provoked even more letters, not only from most states but from Canada, Europe and Asia.

“Memories of the eastern gray squirrel thus seem indelible, even in far-off places,” he concludes. Most of his readers admired the gray squirrel and sent in wondrous accounts of their exploits which he used in his Squirrel Book. However, a substantial minority of readers were not amused. They were grumpy, even acrimonious, toward squirrels.

Last January National Wildlife magazine bravely published “Crazy Over Squirrels.” They, too, received letters. Three of them supported squirrels including Barbara Allen of Pittsburgh who says that squirrels have stolen her heart. On the other hand, J.D. Jones of Milwaukee sums up the squirrel hater’s feelings. “I hate squirrels. They get into my yard, dig up my plants, eat my birdseed and cause all kinds of trouble. I hate them.”

Love them or hate them, yet no one can deny that they provide hours of entertainment in the depths of winter as they raid bird feeders, prompting bird lovers to dream up all kinds of ways to foil them. But as Kinkead warns, “it seems fair to say this to all owners of squirrel-proof bird feeders: they may work for a time. But don’t become too confident. Tomorrow that may change. Tomorrow may arrive the conqueror, the furry Einstein of the out-of-doors.”

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A note to my squirrel-loving book readers: Beg, borrow, or buy a copy of the now out-of-print Squirrel Book by Eugene Kinkead, published by E.P. Dutton of New York in 1980. I found my hard-cover, profusely-illustrated copy at a used bookstore for $5.00 and spent happy winter hours reading it.