8-14 September 2003
Installment #189---Visitor #Walmart Coupons

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(A minute passes.)


(Another half-minute or so.)


That's the frequent but nonetheless startling sound that occurs at Hilton Pond Center each autumn, when squirrels start dropping nuts from a towering Shagbark Hickory tree onto a tin-roofed storage shed less than 50 feet from our computer desk.


All text & photos © Hilton Pond Center

It's almost as if Eastern Gray Squirrels can visualize a bullseye on the shed roof and they're having a contest to see which of their bushy-tailed crew can make the greatest noise with the most direct hits. Fortunately, the metal roof of the office itself isn't directly beneath the hickory's limbs, else we might have cardiac arrest rather than just an ear ache when a nut hurtles down onto the shed.


The outbuilding makes a pretty good target, and the big, round hickory nuts are especially good bombs. Actually, the squirrels aren't lobbing just the nut, but it AND a thick green husk that surrounds and protects the fruit as it ripens (top photo). These spheres are pretty substantial--two inches in diameter and, based on several we checked with an electronic balance, weighing in at almost two ounces--about the same size and heft as a Grade A Large chicken egg. (We can at least be relieved the squirrels have no access to laying hens.)


Shagbark Hickories are well-named. Their gray bark--very smooth in young saplings--begins forming fissures when the trunk gets past about 4" in diameter, and in older individuals the bark begins exfoliating in random patterns (left). Each long, thick bark plate is attached at the middle, with both ends curving away from the trunk and giving the tree a truly shaggy appearance. The Shagbark's scientific epithet, Carya ovata, comes from the Greek word for the walnut tree (hickories are in the Walnut Family, the Juglandaceae) and from the ovoid shape of the fruit. "Hickory" is derived from pawcohiccora, an Algonquin Indian word for the tree's oily nutmeat.


Removing the husk from a Shagbark nut before its time is hard work. Nearly all the fruits that bounce off the shed roof show gnaw marks from squirrels, but even with razor-sharp incisors these arboreal rodents have a tough time getting through the dense green matter. Left to ripen without being molested by squirrels, the husk turns brown, becomes woody, and--when the fruit finally falls to the ground--shatters open in four parts to reveal the nut within (above).


The tan-colored nutshell is quite thick and just as impervious to intruders as the husk. It takes a pretty good whack with a hammer to get at the white nutmeat (right), which Native Americans ground up and mixed with boiling water to make "hickory milk," a flour-like concoction they baked in small cakes. Natural food enthusiasts still favor Shagbark nuts for their sweetness--most hickories have less palatable nutmeats--and are never tossed to the hogs as are fruits from Pignut Hickory, Mockernut Hickory, or the appropriately named Bitternut Hickory.

In addition to the aforementioned Eastern Gray Squirrels that eat Shagbark nuts at treetop heights, other wildlife dines on the fruit after it hits the ground. Eastern Chipmunks are adept at chewing open hickory shells, and even diminutive White-footed Mice will work the nut until they finally get inside. Black Bears are known to tank up on Shagbark fruit prior to hibernation, while Wild Turkeys swallow and then grind the nuts in their powerful gizzards.

European settlers looked to Shagbark Hickories for their excellent fuel value. A cord of split Shagbark wood is said to have the same heat value as a ton of anthracite coal, so many frontier cabins kept warm with Shagbark at the hearth. When burned, Shagbark Hickory produces an especially fragrant smoke that is also used to cure bacon and ham. Lastly, Shagbark's tough, slightly springy wood made it ideal for ax handles and wagon wheels, so all these varied uses meant many a Shagbark Hickory was felled by pioneers--activity that probably led to its relative scarcity in 21st century woodlots. Fortunately, medium-sized Shagbarks often re-sprout from their stumps shortly after being cut, while mature trees may ultimately survive the saw via sucker shoots from their radiating roots. Unfortunately, the species grows very slowly, so it takes a long time for a stand of Shagbark to bounce back after logging.

Most reproduction in Shagbarks, of course, is sexual, but we seldom see female flowers of the big Shagbark Hickory at Hilton Pond Center; they are tiny and form terminally in April in May on twigs high on the tree (above left). The male flowers are much more obvious: four-inch green catkins (right) that yield pollen and then fall by the millions, usually landing in mist nets we have unfurled to catch birds. (One may correctly assume that bird banders don't much care for Shagbark Hickory catkins.) After fertilization, hickory nuts take all summer to develop.


Shagbark Hickory's yellow-green compound leaves (left) are 8"-14" long--usually with five (sometimes seven) lobe-shaped leaflets; these are finely serrated and edged with very fine hairs. (This fuzziness differentiates C. ovata from all other hickories and especially from C. laciniosa, the Shellbark Hickory, which has similar shaggy bark. Shellbark also differs in having elongated fruit and 5-9 leaflets.) Each Shagbark Hickory twig has large leaf scars, plus noticeable white dots called "lenticels" that likely function in gas exchange. Its most prominent feature, however, is a fat, dark brown terminal bud (below right). Fuzzy and quite distinctive, these inch-long buds literally burst open in spring to reveal clusters of fast-growing new leaves (below left). In fall, the mature foliage turns a rich golden yellow.

Although we've seen Shagbark Hickories in the Carolina Piedmont east of Hilton Pond and York County, their more common natural range is from the western edge of the Piedmont to the eastern edge of the Great Plains, and north to the Great Lakes and southern New England. Shagbark is less abundant than some other southern hickories and grows primarily in well-drained soil in valleys and on slopes to altitudes of about 2,000 feet.

It's worth noting that there may be another Shagbark in the Piedmont. Some dendrologists consider the Carolina Shagbark Hickory, Carya carolinae-septentrionalis, to be a separate species, while others lump it as a variety of C. ovata. The Carolina Shagbark's new twigs are thin and black--those of C. ovata are grayish-tan and thicker--and it may grow on drier, more alkaline soils; its nuts are supposedly smaller and leaflets narrower. DNA work is probably needed to determine whether the two types are distinct Shagbark species.

The big Shagbark Hickory at Hilton Pond Center is, to our eyes, a quite handsome tree, tall and straight for the first 50 feet or so and then tilting slightly southward where its branches mingle and compete with those of a huge Southern Red Oak. We've watched the Shagbark grow, albeit slowly, over the 21 years we've lived at the Center, until now it stands about 75 feet and has a trunk more than five feet in circumference and 21" in diameter--very respectable dimensions for a Shagbark Hickory. By the way, the story goes that Andrew Jackson, seventh U.S. president, was nicknamed Old Shagbark because he looked as disheveled as the trunk of this tree. Or maybe Jackson was actually called "Old Hickory" in that he was tough and resilient like the Shagbark's wood. (It's a joke. Granted, a bad one, but we couldn't resist.)

In defense of squirrels that toss hickory nuts at our shed, we should mention that several kinds of insects can infest and abort the fruit, causing it to fall prematurely. These include Hickory Shuckworms (Laspeyresia caryana), Pecan Weevils (Curculio caryae), and Hickorynut Curculio Weevils (Conotrachelus affinis and C. hicoriae). In fact, as we cracked open nut after nut to find just one with photographable nutmeat, we encountered a shell that was "empty"--except for three fat half-inch beetle grubs that consumed the contents and had grown to fill the one-inch nut (below). Tree experts calculate that up to 85% of hickory nuts may be infested by insects in bad years, so it's no wonder we see few Shagbark Hickory seedlings springing up beneath our majestic big tree at Hilton Pond Center.

Regardless of whether insects or squirrels are responsible for premature fruitfall from the Center's towering Shagbark Hickory, at this time of year we're inclined to wear a hard hat whenever we go outside. It's a wise safety precaution--just in case the bombardiers are off-target as they toss hickory nuts from our shaggybark tree toward the metal roof of the nearby shed.



All text & photos © Hilton Pond Center
Flower photos © Paul Wray, Iowa State University,

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Please report your sightings of

8-14 September 2003

Ruby-throated Hummingbird--18
American Goldfinch--2
Black-and-white Warbler--3
Magnolia Warbler--1
Chestnut-sided Warbler--1
Acadian Flycatcher--1
Northern Waterthrush--1
Red-eyed Vireo--1
Northern Cardinal--1
House Finch--1
Summer Tanager--1
Carolina Wren--3
Tufted Titmouse--1

* = New species for 2003

13 species
35 individuals

50 species
860 individuals

(since 28 June 1982)
123 species
42,974 individuals

All text & photos © Hilton Pond Center

This Week at Hilton Pond
is part of the

Chestnut-sided Warbler
Hatch-year individual,
probably a female.

(with original banding date, sex, and current age)
American Goldfinch (1)
04/23/01--4th year male

Tufted Titmouse (1)
06/17/01--2nd year male

None this week

--This week was by far the most productive of the year for Ruby- throated Hummingbirds, with 18 banded at Hilton Pond Center-- including a rather late adult male on 10 Sep. Despite this influx, we've resigned ourselves that 2003 will be one of our poorest hummingbird years since the hummer study began at the Center in 1984.

Back to Preceding Week; on to Next Week

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(Click on the logo at left for details.)
If your group would like to host "Hummingbird Mornings" anywhere
in the U.S. or Canada in 2004 or later, contact
Bill Hilton Jr.


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