A Seedy Month

What a wealth of wildlife food our forest produces in October. Probably our most important crop is acorns from our many mature oak trees.

Early in the month, long before acorns fall off the trees, blue jays come from far and wide to pick them, their calls resounding through the forest as they shell and eat some of them immediately. They carry many more back to their territories in their expandable throats and esophaguses. There they disgorge them in a pile and take them off one at a time, cache each acorn in the ground, and cover it with plant debris, a process called “scatter-hoarding” in scientific circles.

In one study, blue jays traveled as far as five miles round trip, flying easily over human-dominated landscapes, often “planting” them in old fields, vacant lots, and fence rows. Although they eat many of their cached acorns in winter and early spring, enough are left to germinate into tree seedlings. In essence, blue jays are avian “tree farmers,” planting food for future wildlife generations.

Blue jays are not the only creatures that grow new oak trees, although they are arguably the most prolific planters. In Virginia 50 blue jays carried and cached 150,000 acorns in one autumn. Some scientists even credit them with moving oak forests north from their southeastern United States refuges during the last Ice Age at the rate of 380 yards a year.

Gray and fox squirrels scatter-hoard only on their home ranges so they don’t move acorns as far as blue jays, but many of their forgotten acorns also germinate. Gray squirrels are especially dependent on acorns and their populations rise and fall according to their abundance.

Eastern chipmunks and white-footed mice are also acorn-dependent, but they store most of them in underground larders usually too far below ground or too crowded in piles to germinate. In fact, researchers in a managed central Pennsylvania forest discovered that white-footed mice were responsible for eating and caching nearly two-thirds of the acorn crop.

Many other species of birds and mammals, such as black bears and white-tailed deer, depend on acorns to build up their winter fat reserves. Luckily, we have trees from both the white oak group (white and chestnut oaks), which produces some acorns every year and occasionally a bumper crop, and the black oak group (northern red, scrub, black and scarlet oaks), which matures every second year when they produce bumper crops. Except for a couple years during the gypsy moth outbreak in the early eighties when the oaks were too stressed to fruit, our wildlife can always depend on at least some acorns to see them through the winter.

Other acorn enthusiasts are raccoons and wild turkeys. One observer watched as one turkey ate 77 whole black oak acorns and another 35 whole red oak acorns. Other acorn-loving birds are white-breasted nuthatches, ruffed grouse, and red-bellied woodpeckers. Last October I watched a red-bellied store two acorns in a hole in one of our yard black walnut trees.

Black walnuts, like acorns, beechnuts, and hickory nuts are fruits with a dry, hard exterior. Although acorns are relished by nearly 100 species of birds and mammals, the thick, hard shells of hickory nuts and black walnuts make them inaccessible to most animals except squirrels and chipmunks. Squirrels also scatter-hoard black walnuts in our yard, but they allow many others to remain where they fall.

Because of the walnuts, we rarely have trouble with squirrels at our bird feeders. Only in the six winters out of 30 when our black walnut crop failed, did gray squirrels invade our feeders. For a short time last winter the walnuts were covered by a layer of ice so the gray squirrels ate our birdseed until the ice melted. Then they, along with a visiting fox squirrel, resumed digging up and eating walnuts.

One February morning I counted 15 squirrels in the yard and watched as they trooped back up into the woods with their treasure. No matter how many walnuts cover our yard in the autumn, they are all gone by the following spring.

Hickory nuts are even more popular. We have so few hickory trees in our forest that the nuts are consumed on the spot by squirrels before they are fully mature in late August and early September. Should any be left, chipmunks, fox squirrels, wild turkeys and red-bellied woodpeckers also like them.

Beechnuts are another favorite wildlife food, but American beech trees do not produce a crop of the burr-encased, sweet, triangular-shaped nuts every year. When they do, deer, black bears, raccoons, squirrels, chipmunks, ruffed grouse, wild turkeys, blue jays, tufted titmice, and red-bellied woodpeckers harvest them. Most of our mature beech trees grow beside the stream and many drop their nuts on our access road, so they are instantly hulled by our car. Like hickory nuts, they are so prized by wildlife that I usually find only the empty prickly burrs.

Forest trees also produce seeds packaged in fleshy fruit attractive to birds and animals. The plan is for the creatures to eat the fruit whole and defecate the seeds intact so they can germinate into tree seedlings. In the case of black gum trees, the big, thick-walled seeds are too large for many songbirds to swallow so they only eat the dark blue fruits, but black bears, gray squirrels, raccoons, foxes, and wild turkeys also like the fruit and no doubt “plant” the seeds too.

Back in October 1998, our black gum trees, alternately called black tupelo, sour gum, or pepperidge, produced a bumper crop of fruit. I spent many happy hours watching those cafeterias for migrating and resident birds. My personal list included cedar waxwings, northern flickers, American robins, scarlet tanagers, yellow-bellied sapsuckers, hermit thrushes, eastern bluebirds, and red-bellied woodpeckers. Other observers have recorded brown thrashers, wood thrushes, European starlings, pileated woodpeckers, and red-eyed vireos eating black gum fruits. Strangely enough, the sapsucker I watched made sap wells and ate both sap and fruit.

We are lucky to have a healthy population of flowering dogwoods in our forest. Their bright red fruit clusters are not only attractive but favorite wildlife food. The fruits themselves are eaten by ruffed grouse, wild turkeys, cardinals, bluebirds, robins, brown thrashers, all species of thrushes, red-eyed vireos, and cedar waxwings, but the seeds are favored by squirrels, chipmunks, and white-footed mice.

Dogwood fruits, like those of our other abundant October wild fruit producers–wild grapes and Hercules’ club trees–are especially important because they hang on through late fall and winter, when permanent residents need food. I’ve written before of how popular the heavy clusters of black Hercules’ club berries are with robins and cedar waxwings. In the last couple autumns flocks of migrating starlings have been competing with the robins and waxwings in the extensive grove of Hercules’ clubs in our ten-year-old clearcut. Lately I’ve seen occasional cardinals and once a fox sparrow eating them. Other sources mention Swainson’s thrushes and wood thrushes. Mammals include red foxes, skunks and chipmunks, and, as I discovered a couple years ago, black bears.

Over 150 years ago the New England naturalist Henry David Thoreau wrote about birch seeds in notes he entitled “The Dispersion of Seeds”–“When this seed is most abundant, great flocks of lesser redpolls come down from the north to feed on it and are our prevailing winter bird. They alight on the birches and shake and rend the cones, then swarm on the snow beneath, busily picking up the seed in copses. Though there may be but few birches, white or black, in the midst of a wood, these birds distinguish their tops from afar…I also see the goldfinch…eating the birch seed in the same manner.” And the pine siskin, I might add.

Whenever we have a winter invasion of these northern seed eaters, I always spot them first among the birches. In the winters when there are no northern finches, black-capped chickadees and dark-eyed juncos harvest the seeds. Other observers report seeing ruffed grouse, fox sparrows, and chipmunks eating them.

Birch seeds, unlike the other trees I’ve mentioned, are dispersed by wind and resemble, according to Thoreau, “tiny, brown butterflies.” He also counted 1000 seeds packed in each cone or strobile. “Wind dispersal,” Peter Marchand writes in his excellent book Autumn: A Season of Change, “is a gambler’s approach,” and the least successful method of dispersal. That may be so, but we have many, many black birch trees that supply bird seed year after year.

Next to acorns, wild grapes probably provide the most food for wildlife in our forest. During the infestation of gypsy moth caterpillars, wild grapes kept many of our birds and animals alive during the winter. The Far Field thicket, then heavily overhung with grapes, provided both food and cover for white-tailed deer. One winter they were so hungry that they ignored me as I sat in plain view and watched them slowly and painfully moving around in search of fallen grapes. Now that the oaks have recovered, wild grape thickets still provide great wildlife watching from fall until spring.

Flocks of robins, cedar waxwings, and white-throated sparrows often winter among the grapevines, and the fruit is also eaten by ruffed grouse, wild turkeys, cardinals, fox sparrows, thrushes, pileated and red-bellied woodpeckers. One autumn I watched 10 rusty blackbirds feeding on grapes, and long ago, when evening grosbeaks wintered here, they spent a lot of time eating grapes and their seeds.

Mammals that like grapes include black bears, red and especially gray foxes, raccoons, skunks, opossums, and fox squirrels, among others. Eastern box turtles are also enthusiastic consumers of wild grapes. Some researchers report that when wild grape seeds pass through the gut of the box turtle, their viability is actually enhanced, perhaps because the turtle’s digestive juices help break down the hard exterior of the seeds. The seeds also may take several days to pass through the turtle, during which time it may move several hundred feet, dispersing the seeds to new locations. So box turtles may be unintentional viticulturists!

The production and dispersion of seeds occurs mostly from April until November, but there is no doubt that in our forest October is the seediest of months. “Convince me that you have a seed there, ” Thoreau wrote, “and I am prepared to expect wonders.” If that is true, then our forest is truly a wonder.