Fox Squirrel Dossier

by Carl Strang

This week’s species dossier is one of my larger ones.

Fox Squirrel

Fox squirrels are distinguished from our other common tree squirrel, the gray squirrel, by the reddish tones in the tail and belly.

This is a squirrel of woodlands and residential areas with trees. The fox squirrel is the only large tree squirrel of the Culver, Indiana, area. They nest in tree cavities or in leaf nests; some used leaf nests all winter at Willowbrook Forest Preserve, Illinois. Nest building involves cutting of leafy branch-ends. A leaf nest in cross section is made of those leafy twigs, woven into a framework of thicker sticks, with a fresh leafy lining. Overall it has a very thick wall with small insulated cavity within.

Squirrel nests are approximately the diameter of a basketball.

Fox squirrels feed on the ground and in trees. They begin to eat acorns and hickory nuts in August when those still are green. Hickory nuts and acorns are consumed in treetops, especially early in morning and late in afternoon, resulting in a distinctive rain of fragments as hulls are gnawed away. Squirrels (gray squirrels?) also ate black gum fruits in Pennsylvania on Reineman Sanctuary in late fall. Generally they open large nuts (hickory, walnuts) neatly, prying them open on the seams.

Fox squirrel with a pair of shagbark hickory nuts.

They also bury individual acorns, nuts, black cherry pits, etc., in the fall. Distinctive burying site goes into earth at a 45 degree angle or a little shallower, producing an oval shaped bare soil excavation site about 1×2 inches (wider than tall) in soft soil, smaller in hard soil. Mushrooms also are on the fall food list near Culver. Diet in early winter emphasizes excavated nuts buried earlier.

Squirrel tracks, right, follow a winding course as the animal sniffed for a buried nut. On the left is the hole where it excavated one.

Twigs and bark, e.g. of elm, eaten occasionally in mid- and late winter. Buds, e.g. of maple, are added as those expand in spring. Developing elm seeds are heavily consumed in May in DuPage County, generally twigs are cut and seeds eaten from them. Occasionally they gnaw bones.

Fox squirrel eating buds in spring.

Fox squirrels have two breeding seasons, typically, in spring and fall, with 2-5 young per litter. Young began to appear at the Willowbrook Wildlife Center hospital in mid-March (born mid-late February) and mid-August (born late July or early August). Young normally begin to emerge from the nest in May or late September. Young play in vigorous chasing and hiding games on tree trunks and in branches, occasionally extended onto the ground. Adults sometimes play as well, also tease dogs. Leap between trees. They use suspended wires as tightropes between trees and over roads.

These could be fox or gray squirrel footprints.

Tree squirrel tracks are distinctive, the 5-toed hind footprints about 1.25 inches long, with 3 parallel middle toes close together, pointing forward, and outer toes pointing out at angles. The 4-toed front footprints show more spread and independence of toes. The traveling gait typically is a gallop, with front feet leaving ground before back feet land. The back feet are side by side, as are the front feet. Slowing down causes front feet to get closer and closer to back footprints, until one or both front footprints are in front of the back feet. Acceleration also begins with a set of footprints showing the bound gait. Squirrels sniffing slowly over the ground sometimes use the diagonal walk. Fox squirrels show considerable ingenuity and acrobatic ability in overcoming bird feeder protections.

Early spring 1986, Taft Campus of Northern Illinois University, north central IL, with snow still on ground. A fox squirrel, opportunistically foraging in a temporary meltwater stream, looked much healthier than the many gray squirrels fastidiously foraging on the wet-snow-covered hillside nearby.

24NO86. Squirrel began to go onto a branch with 2 great horned owls. The squirrel stopped, tail twitching, sat still for a while, then backed and started to go on a branch over the owls’ heads. They were watching it. Finally it turned around and ran down the tree.

12DE86. Puffer Lake, Morton Arboretum, IL. Fox or gray squirrel tracks in snow that fell yesterday afternoon, on ice among cattails at edge of lake. The tracks were made early this morning. Diagonal walk first 7 feet onto ice, then slow gallop gait.

Fox squirrel, winter.

14MR87. Fox squirrel eating cherry and elm buds at Maple Grove Forest Preserve.

30AP87. Fox squirrel feeding heavily, frenetically, on large green silver maple fruits (seeds only; dropping wings). Also on 1MY, 8:30 a.m. both days.

4MY87. Squirrel-cut elm twigs with fragments of seeds on ground.

6MY87. Early evening, a fox squirrel feeding in an elm top at Willowbrook. Mostly clipped twigs first, then stripped them of seeds, and finally dropped them. The squirrel removed more foliage in 3 minutes than a noctuid caterpillar would in its entire life.

18DE87. 4 days after an abrupt 1-foot snowfall, little but rabbit and squirrel tracks can be seen in the Willowbrook Back 40. The latter are relatively few, restricted to woods.

25MY88. A squirrel when being stealthy carries his tail behind him like the cloak on a figure in an old novel.

This one looks pregnant.

29MY88. Fox squirrel numbers at Hartz Lake (in Indiana) appear limited by hickories. The few squirrels I’ve seen to date have been in parts of woods where hickories are (may simply be a preference, if hunters are keeping numbers low).

20SE88. A fox squirrel nest came into Willowbrook from Lombard with 3 young. The nest was made of leafy elm twigs, with grasses and a work glove toward the center. Overall shape was like an urn, with branches interwoven to nearly cover the entrance. Couldn’t tell for sure whether the entrance was on top or side. Nest blown out of tree by storm.

27JL89. Fox squirrel still feeding heavily on red half-ripe mulberries at Willowbrook after purple ripe ones have been available more than 1 month.

10MR90. Warrenville Grove Forest Preserve. Fox squirrel lunges up tree when climbing, pushing with all four feet at once. Toes catch in cracks, don’t appear to slip although a slight adjustment with a foot may be made now and then before the next lunge.

24JL90. Fox squirrel still eating mulberries.

15NO90. Willowbrook. A fox squirrel eating catalpa seeds right out of the pod, and letting the wings fall.

13JA92. Fox squirrel eating box elder buds, Willowbrook.

22AP95. Midafternoon, Warrenville Grove Forest Preserve. 2 fox squirrels feeding heavily on American elm buds in a 6″dbh tree.

13OC96. 3 fox squirrels in full bark, simultaneously, in Mom and Dad’s Culver front yard. A large cat was their target. They were turned so their bodies pointed in its direction and they were focused, looking straight at the cat.

Not a hibernator, the fox squirrel remains active all winter.

19FE99. Fox squirrel eating expanding silver maple buds, Willowbrook.

4MR99. At mid-day a gray squirrel emerged from a hole in a large, dead willow at Willowbrook to drive away an approaching fox squirrel. The gray immediately returned to the hole.

20AP99. Fox squirrel feeding on buds or expanding leaves of a black cherry tree with leaves much more expanded than those of other cherries at Willowbrook.

28AP99. Willowbrook. Fox squirrel eating silver maple seeds.

13OC99. Willowbrook. Young fox squirrel out of nest. Another fox squirrel eating box elder seeds.

21OC99. Willowbrook. Several fox squirrels gathering walnuts.

Synchronized acorn-eating team, Mayslake savanna.

27OC99. Fox and gray squirrels both are active. The former have been eating nuts in recent days, one this morning in a box elder eating seeds, another appearing to work on a broken down old nest.

28OC99. Gray squirrel with nut, fox squirrel eating box elder seeds.

1NO99. Willowbrook again. Fox squirrel eating box elder seeds.

17NO99. A gray squirrel (young) and a fox squirrel both eating box elder seeds at Willowbrook.

2DE99. Several gray squirrels and 1 fox squirrel foraging on the ground.

30DE99. Fox squirrel at Willowbrook building leaf nest 15 feet up in a buckthorn in a tall-brush area. Taking leaves from nearby small oak that had not dropped many of them.

2FE00. A fox squirrel carried a ball of snow up onto a branch and ate from it.

14FE00. Many gray and fox squirrels this winter in nests only 12‑14 inches outer diameter at Willowbrook.

25FE00. Willowbrook, afternoon. 2 fox squirrels eating buds from a mulberry tree rich in witches’ brooms. Temperature 70F.

2MR00. Willowbrook. 2 fox squirrels sharing a hole in the trunk of a large willow, 1 of them adding leaves picked up from the ground.

Grooming the fur.

4MR00. A gray and 2 fox squirrels feeding on the expanding buds of an American elm near the Joy Path of Morton Arboretum. As I left the path to approach the tree to identify it, the gray squirrel immediately left and ran to other trees. As I walked up to the trunk, the lower of the fox squirrels finally left, but the higher one remained.

15MR00. Willowbrook. Fox squirrel nest high in the very top of a red oak across the exhibit trail from the eagle cage (occupant barked at another fox squirrel lower in tree). A fox squirrel eating expanding sugar maple buds.

13AP00. A fox squirrel feeding on expanding sugar maple buds, Willowbrook.

19AP00. Willowbrook. 2 fox squirrels eating expanding sugar maple buds.

7MY00. West DuPage Woods F.P. 2 fox squirrels clipping American elm twig ends and eating the nearly ripened seeds, then dropping the twigs with leaves.

1JA02. A fox squirrel at the Arboretum eating honey locust seeds from a thornless tree on a very cold day. Sometimes it ate individual seeds from the pod attached to the tree, sometimes removed entire pods and took the seeds from them.

This fox squirrel was mobbed by a pair of Baltimore Orioles in June of 2009 until it left their nest tree.

5OC10. Mayslake. A fox squirrel chased a gray squirrel on the ground in the south savanna.

27JA11. Mayslake. Fox squirrels feeding in thornless honey locust in south (former) friary grounds, presumably getting seeds from pods.

1DE11. Fox squirrel eating honey locust seeds from pod on ground.

Prehistoric Life 19

by Carl Strang

This year’s winter series has been a review of the prehistoric life and geologic history of northeast Illinois. Each chapter has summarized current understanding, gleaned from the literature, of what was going on with life on Earth in a particular span of time, what we know about the local landscape, and what we can say about local life. I include some references, particularly to papers published in the journal Science which commonly is available at public libraries. Contact me if you need sources for other items. The Earth is so old that every imaginable environment was here at some point, from ocean depths to mountaintops, from equatorial tropics to tundra, and from wetlands to desert. Today’s chapter concludes the series.

At last we reach the most recent times. This mastodon and its kind lived in our area in the recent past.

Pleistocene Epoch (1.64 million years ago to the present day)

The Pleistocene Epoch (named 1839), literally “most recent,” marks the latest series of continental glacial times. We are in an interglacial interval, regarded as part of the Pleistocene by some, by others named separately the Holocene (1885) or Recent (1833) Epoch.

Life on Earth. This is the time when our human species Homo sapiens evolved, along with the rest of the modern species. Our species originated in Africa around 200,000 years ago as it separated from its earlier hominid precursors, then began to migrate out of Africa around 100,000 years ago, fanning out into Europe, Asia, Polynesia-Australia and ultimately North America. Homo erectus earlier (1.5 million to 770,000 years ago) ranged from Kenya to China (Science 323:1197, 1419). Shaped tools and red ochre use suggest modern-like behavior had begun to appear by 164,000 years ago (Science 318:777). Genetic studies indicate that the Neandertals were a separate species, though they shared with us a gene for speech communication (Science 318:546). Skin color may have diversified in our species much more recently, with pale skins in some races developing only within the past 5300-12,000 years (Science 316:364).

Reconstructed giant ground sloth, Mastodon State Historic Site, Missouri.

There were new arrivals in North America from South America: 2 sloth genera (Nothrotheriops and Eremotherium), opossum, anteaters. And, from Eurasia, mammoths, bison, saiga, musk oxen, and humans. The polar bear evolved away from brown bear ancestors of the southeast Alaska area around 150,000 years ago. Many large birds and mammals became extinct, in many areas (including North America) because of human hunting (Science 300:885; 306:70).

Local landscape. This was a time of ice ages, more than 20 periods of continental glaciation alternating with periods when the glaciers retreated (only 4 of these reached as far as the Mississippi River drainage basin). The dominant theory ties the growth and ebbing of glaciers to regular cycles in the Earth’s orbit, tilt, and precession. Up until 1 million years ago, the glacial cycles were 41,000 years long, corresponding to the cycling of the Earth’s tilt. For the past million years the cycle has become 100,000 years long, for reasons that are unexplained but may be connected to a change in atmospheric carbon dioxide.

Rotten or weathered rock had formed at the surface; most of this was removed by Pleistocene glaciers. Glaciers don’t remove much thickness of bedrock, however, carrying mostly fractured pieces. In the DuPage County area, the glaciers scoured the Silurian dolomite bedrock clean of any sediments, except for the Devonian or Mississippian marine clays in cracks on the upper surface (this is why there are no pre-Pleistocene terrestrial fossils in much of northeast Illinois).

If we could clear the glacial deposits from our bedrock we might see something like this, grooves scratched on the surface by the glacier as it pushed southwest out of the Lake Michigan basin. Rock Point, Ontario.

Dolomite bedrock escarpments such as the one tracing the western and southern boundary of the Lake Michigan basin, and other highlands such as the northern Wisconsin Arch, played a significant role in channeling glacial flow. Lake Michigan started as a south-flowing stream. The sequence and timing of events: the Nebraskan glacial advance 1.8mya (million years ago), then the Aftonian interglacial stage, then the Kansan advance 900-600kya (thousand years ago), then the Yarmouthian interglacial, then the Illinoian advance 400-300kya, then the Sangamon interglacial, then the Wisconsinan glacial advance began 100kya and ended 18kya. Within the Wisconsinan there was an Altonian advance 70-30kya that reached northeast Illinois, a retreat 30-22kya called Farmdalian time, and the largest final advance 22-18kya called the Woodfordian.

A continental glacier was not a single body, but rather several rivers of ice, or lobes, flowing side by side. The Silurian escarpment divided the Lake Michigan lobe from the Green Bay lobe. Kettle Moraine in Wisconsin is a glacial deposit left between those lobes. The Lake Michigan Lobe had to climb (be pushed) several hundred feet to overtop the escarpment and enter northeast Illinois.

As the glacier advanced, the Straits of Mackinac outlet became blocked, and Lake Michigan drained south through the Chicago and Des Plaines Rivers. The Glenwood phase of Glacial Lake Chicago, as it is called, was followed by alternating advances and retreats that blocked and opened the Mackinac Straits and further eroded the Des Plaines valley. Because the weight of the glacier had depressed the crust, for a time after the last glacial retreat the river through the Straits lowered Lake Michigan (in that incarnation called Lake Chippewa) to the point where it was much smaller and occupied only part of its current area. Crustal rebound later raised the northern end of the lake to the point where the current basin filled. When the Upper Peninsula of Michigan, Lake Huron and part of Lake Superior were cleared of retreating glacial ice but other outlets still were blocked, the Des Plaines became the major drainage for all three lakes.

In 2007-2008 Mastodon Camp, a partnership between the Forest Preserve District of DuPage County and the Field Museum of Natural History, gave high school teachers and students an opportunity to participate in a dig. Bits of mastodon bone and tusk, as well as buried black spruce trees and cones, were the main physical product from the site at Pratts Wayne Woods Forest Preserve.

During the latest, Wisconsin glaciation, the permafrost (tundra) zone was 50-120 miles wide beyond the glacial margin, and the mean annual temperature was about 5 degrees C cooler than today. Most of our familiar prairie and forest species were restricted to rather small refuges in the South during the glacial maximum, though oaks and hickories occupied a large part of the southern U.S. Species occurred in unfamiliar combinations, which changed as environmental conditions shifted (i.e., distributed themselves according to individual species tolerances rather than in community clusters of species).

According to recent work with cores from Nelson Lake in Kane County and Brewster Creek in DuPage, our landscape originated 18,000 years ago as the Wisconsin glacier melted away. By 17,000 years ago the glacier locally had shrunk back to the Lake Michigan basin. Open sedge tundra with some spruce trees invaded the zone nearest the glacier (18,000-16,000 years ago), then white spruces filled in to form a recognizable northern coniferous forest until around 15,000 years ago. The climate was dry and windy, piling a layer of loess (silty material) on top of the glacial till and outwash. The wind diminished and the climate became wet around 15,000 years ago because of the collision of warm air from the Gulf with polar air from the glacier north of us. White spruce declined, with black spruce becoming important in low wet areas, and black ash and fir along with a variety of deciduous trees invading the uplands. The glacier retreated to Canada by 13,000 years ago, then advanced in a new cool period as far as northern Wisconsin and the U.P. of Michigan (this may have been a Northern-Hemisphere-only cooling: Science 318:86), and began its final retreat 11,650 years ago. Then alder, birch, jack pine, ironwoods and elms increased locally, and additional trees invaded until a mix of deciduous species, including lots of oaks, was achieved. Beginning around 10,000 years ago there was a drying period, which led to the spread of prairie through our area. The prairie then retreated a little, so that by 6200 years ago our area became a prairie with islands of woodlands.

Local life. After the Wisconsin glacier retreated, first there was tundra, home of woolly mammoths (grazers), musk oxen, caribou, collared lemmings and other animals now extinct or found only in arctic Canada and Alaska. People arrived at this time, hunting with spears (one of the earliest human sites in North America, with butchered mammoth bones dated at 12,500 years ago, has been discovered just north of here near Kenosha; Science 305:590). As the forest filled in the warming landscape, additional mammals included moose, stag moose, scimitar cats, dire wolves, giant beavers, snowshoe hares, Jefferson’s ground sloths and mastodons (unlike mammoths these were browsers which also ate walnuts, spruce cones and other seeds; some species such as Kentucky coffee tree and osage orange are thought to be relatively uncommon today because they have lost mastodons and other large herbivores as seed dispersers). During the time of deciduous forest, local mammals included mountain lion, bobcat, red wolf, elk, white-tailed deer, raccoon, gray fox, porcupine, black bear, flying squirrel and gray squirrel. The prairie and mixed prairie savanna of historical times included today’s familiar animals, along with black bears, badgers, mountain lions, red wolves, elk and bison.

Imagined Paleoindians, Mastodon State Historic Site, Missouri.

Clovis points have been found in DuPage County, indicating that some of those early big animal hunters (known as Paleoindians) were here. The largest animals became extinct, thanks in large part to the Paleoindians’ killing them faster than they could reproduce (Science 326: 1100). Subsequent human cultures wandered less, and shifted to more of a hunting-gathering economy in the several thousands of years of the Archaic Period. Thrust spears and spear-throwers did not give way to bow and arrow in North America until later, during the Woodland Period that began with early signs of agriculture about 2000 years ago. Agriculture did not become an important part of the local economy until the most recent 1500-1000 years. The Woodland people were even more sedentary than Archaic people, and used pottery. Mississippian and Oneota cultural influences, centered in west central Illinois and Wisconsin, respectively, were characterized by increasing social-political complexity made possible by corn-based agriculture. Ultimately the familiar tribes emerged, in northeastern Illinois the Miami followed by the Potawatomi.

For a time in recent years, a group of researchers attempted to make the case that a comet or other extraterrestrial object exploded over North America, causing a climatic cooling (the Younger Dryas time), ending the Clovis culture and resulting in the extinction of the North American megafauna. By the end of 2010 a number of studies had invalidated the supposed evidence for this idea and shown that the Younger Dryas was the result of a sudden influx of cold, fresh glacial meltwater into the northern oceans that for a time shut down the Gulf Stream current.

Prehistoric Life 16

by Carl Strang

This year’s winter series is a review of the prehistoric life and geologic history of northeast Illinois. Each chapter will summarize current understanding, gleaned from the literature, of what was going on with life on Earth in a particular span of time, what we know about the local landscape, and what we can say about local life. I include some references, particularly to papers published in the journal Science which commonly is available at public libraries. Contact me if you need sources for other items. The Earth is so old that every imaginable environment was here at some point, from ocean depths to mountaintops, from equatorial tropics to tundra, and from wetlands to desert.

Oligocene Epoch (35.4-23.3 million years before present)

The Oligocene Epoch (named in 1854), literally “little recent,” was divided from the Miocene of which it originally was part, based on fossils in Germany.

Life on Earth. The first grassland ecosystems appeared in Asia in the Oligocene, a profound step in the history to follow.

At the beginning of the Oligocene there was a big diversification of North American mammals, with only a quarter of the Eocene genera continuing. Change was slow for the rest of the epoch. This rapid change, preceded by a wave of extinctions, is associated with a time of climatic cooling. Relatively little is known about the Oligocene, because its general lack of change after the beginning has interested few researchers.

Those peculiar derived artiodactyls, the whales, continued their slow evolution through the Oligocene.

The oreodonts were a diverse North American artiodactyl (even-toed ungulate) group in the Oligocene; they declined to extinction at the end of the Miocene. The early Oligocene was the time when the browsing perissodactyl titanotheres (brontotheres) peaked in North America and Asia. Another perissodactyl, the giant rhinoceros Paraceratherium of Asia (also known as Indricotherium or Baluchitherium), is the largest known land mammal ever. It lived in the Oligocene and Miocene, was 18 feet high at the shoulder and could reach twigs and leaves 20 feet off the ground with its 5-foot-long head.

The ground sloths evolved in South America, the first ones appearing in the Oligocene fossil record.

Early in the Oligocene the first beavers appeared (in North America), the first procyonids (raccoon family) in North America and Europe, the first peccaries in North America. The Middle Oligocene brought the Canidae (dog family). Paleosciurus tree squirrels first appeared in the early Oligocene in Europe (Science 299:1568).

Peccaries, another artiodactyl group, evolved into existence in the North American Oligocene.

The hyaenodontids and nimravids became extinct in the late Oligocene, resulting in the “cat gap,” a lengthy period of time in which the North American carnivore fauna was dominated by larger canids and amphicyonids, and smaller mustelids (weasels), but nothing resembling a cat. The first ground sloths evolved in South America in the Oligocene.

Local landscape. A turning point in post-Cretaceous times was the separation of Australia from Antarctica in the late Eocene. The consequent establishment of a permanent cold current around the latter continent in the Oligocene brought a cooling to the global climate that impacts us to this day. Brief but intense glacial episodes, set off by changes in Earth orbital characteristics and made possible by the cold south polar currents, happened both at the beginning and end of the Oligocene (Science 314:1894). The cooling trend continued until our local climate became temperate in the Oligocene. Deciduous dry forests passed from semi-tropical to temperate.

Grassland ecosystems still were in North America’s future, but they had their start in the Oligocene, in Asia.

The oak family became more important both east and south of here. In the Plains to the west, hackberry was common, and that region may have been a low-rainfall scrubland (remember, no grasslands were here yet). The closest Oligocene deposits are in south central South Dakota and western Nebraska.

Local life. One or more species of the carnivore-like creodont Hyaenodon probably occurred here in the Oligocene. Oreodonts also were diverse, then, and likely were represented here. There were widespread, hippolike rhinoceroses called amynodonts in North America and Eurasia. Horses in the genus Mesohippus also were likely here.

Eastern Cottontail Dossier

by Carl Strang

My species dossiers focus on vertebrate animals, and as there are many more birds than other terrestrial vertebrates, most of the dossiers I have shared had avian subjects. Today’s focus is a mammal.

Cottontail, Eastern

These live in weedy and brushy habitat. Occasionally enter forests, especially in fall and winter. Maintain a network of trails and runs. Have aboveground forms or beds used for much of the year, but take cover in sheltered spots (in firewood pile at Warrenville, IL, for instance, during daytime in a neighborhood with little cover) and in burrows (woodchuck burrows at Culver’s fish ponds, skunk burrow at Willowbrook), and culverts. Predators may influence this: in winter of 1998-99, cottontails seldom appeared in the open, but coyotes were omnipresent and often dug at ends of drainage culverts under the nature trail, where rabbit tracks led.

Cottontail nest, opened slightly to show hairless infant.

Young born blind and hairless. Nest in short grass areas (e.g., lawns, examples seen at Boiling Springs, PA, and in IL), in shallow depression lined and covered with a mix of fur and grass. Nest well hidden. Young become independent when about 4 inches long, when ears stand up and fur becomes shaggy. Mother simply abandons nest (normally she visits it only at night), young find their way out. Observed a youngster at Lombard, IL, learning to recognize food. Sniffed every plant, occasionally nibbling one, occasionally chewing one down to ground. Can be tame and easily caught first day or two out of nest.

Summer food green plants, for instance dandelions (watched one at Boiling Springs, PA, as it ate fruiting stalks, biting them off near ground then nibbling them into mouth endwise, seed poofing out as it reached the end). Browses in winter. In DuPage County, rose family preferred (or at least eaten first, then when other foods depleted, larger rose and Rubus stems cut to bring twig ends within reach), others eaten include twigs of maple, elm, bittersweet Solanum dulcamara, poison ivy (the last toward winter’s end). Patches of red to orange urine at this time. Bark of cherry, elm, sumac, taken in leaner winters.

Often the toenail marks are the only clear indicators of a cottontail track. The furry feet do not make a clear impression in hard soil.

Droppings distinctive, round. Tracks occasionally show the 4 nailed toes in good conditions. Hard substrates sometimes reveal 4 toenail marks in wedge shaped pattern. In snow, typically nothing more than round depressions for front feet, elongate ones for hind feet. Rarely anything but a gallop gait with one front foot in front of the other.

16AP86. Rabbits eating gray dogwood bark in Willowbrook Back 40, both of standing shrubs and of stems I cut earlier this week.

9JL86. Watched a half-grown cottontail through the window at Willowbrook as it grazed. Seemed to select younger grass blades (pointed rather than mower-cut; lighter in color).

9FE87. Inside Willowbrook main building, cottontail escaped from intensive care room during night. Droppings and smears of dust suggest that it got into the clinic, somehow got up onto 3 foot high counter top, then another 4 feet up to cabinet top. [I asked Tom Brown about this; he has seen even higher vertical leaps onto ledges by cottontails].

This is the cottontail that escaped in the Willowbrook Wildlife Center hospital and hid by jumping from the floor to the countertop, then from the countertop to the top of the wall cabinet.

12FE87. Cottontail recently gnawed on crabapple beside trail.

15MR87. Meacham Grove. Rabbit moving fast, but turning: the space between the front feet and hind feet decreased as it approached the turning point, revealing a slight deceleration; the front feet pointed in the direction it had been going, then the hind feet pointed in the new direction. This rabbit placed its front feet side by side. The distance between the front and hind tracks was not related to the distance of the leap: large and small for long and short hops. I tracked this rabbit to its hiding place, partly under a log in open woods. I had passed within 8 feet of him twice, then stood 3 feet away for at least 2 minutes puzzling over tracks that seemed to go into there but not out, when he burst from hiding and ran away. The rabbit had climbed up on sticks and logs a few times (crossways to his route).

A typical cottontail footprint pattern with the more elongate hind footprints side by side, rounder front footprints one before the other. In each step the hind feet carry past the front feet.

MY87, NJ Pine Barrens. Cottontail browsing blueberries, oaks.

AU87, NJ Pine Barrens. Cottontails smaller here than elsewhere.

12AU87. Assateague Island, morning. Young cottontail eating clovers (several patches well nibbled, English plantain flower stalks, a wiry upright narrow-leafed composite, and another plant that resembled common ragweed. Avoided the abundant Senecio. Had several ticks in its ears, and appeared to have a partial cataract in the right eye.

18DE87. 4 days after an abrupt 1-foot snowfall, little but rabbit and squirrel tracks in Willowbrook Back 40. Former’s mainly at edge of field and woods.

23JA88. McDowell Forest Preserve. Rabbits and foxes highly active last night (an inch of snow fell just after sunset). One rabbit, at least, was in underground burrow during snow. Unusual amount of side-by-side front foot placement by rabbits: slippery or uncertain new surface? One rabbit fed on grasses, edge of a tall grass field.

On slippery or unfamiliar surfaces (e.g., the first snow of the season), cottontails often lock their front feet together side by side. I assume this gives them more stability. You can see in the dossier text when I discovered this.

27JA88. Willowbrook. A rabbit had moved along left edge of path, paused and looked back down path over right shoulder. Both front feet to right of their usual position and pivoted, right foot 45 degrees. This is enough to allow the rabbit to look behind it (eyes on sides of head).

28JA88. Willowbrook. A rabbit did heavy browsing on a rose bush last night.

3FE88. Willowbrook. In the 2 nights since the last snow, not real cold, lots of activity. Rabbits, squirrels, mice, fox, raccoons, cats. Icy beneath. Again, lots of rabbit track sets with side by side front footprints.

LateFE88. Tracker Farm, NJ. Rabbit browsed rose since 1 JA.

6JE88. Baby rabbit tasting rocks, licking them, in Willowbrook streambed. Ate silver maple seed, elm seedling.

13DE88. Rabbits commonly placing front feet side by side on longer steps after about an inch of snow fell early last night atop the half inch that was there from 3 days previous.

1MR89. Rabbit’s front feet indicate the direction from which it came more reliably than the hind feet point to where it’s going, at least when it is traveling slowly. Look to pressure releases as well. In today’s crusty snow, the rabbit leans in the direction it’s going, so that in forward hops the toes are deepest. In an abrupt left turn the left edges of both hind prints were deepest.

12MR89. Hartz Lake. Dense poison ivy area between cemetery and prairie heavily browsed recently, mainly by rabbits.

25AP89. A rabbit nest, now empty with lining scattered. In the low, flattened blackberry tangle beside the nature trail at Willowbrook. Scattered taller brush on all sides.

These baby cottontails are weaned or nearly so. The mother simply stops coming to the nest and the young, driven by instinct and hunger, leave the nest and start learning which plants are good to eat.

3MY89. Willowbrook. Another rabbit nest yesterday on the side of the hill constructed of fill from marsh excavation. Like the nest last summer on the steep hillside at Clarks’, this hole was deep.

4MY89. Willowbrook. Yet another rabbit nest, this one in fairly thick brush 5 feet beyond the cleared edge of the main trail.

9MY89. I mistook moss for a cottontail. Sometimes the agouti pattern resembles mossy mottling.

22JE89. Rabbits eating common ragweed at Willowbrook.

31JL89. Willowbrook. Rabbits bending down Queen Anne’s lace and common ragweed and eating tops, along Nature Trail.

18AU89. Cottontails reaching common ragweed tips 4 feet off ground. Apparently, from bruise patterns and broken stems, they are pulling the plants down.

24NO89. Hartz Lake. Rabbit stopped, sat, turned. Entire left edges of both hind feet show pressure releases.

13DE89. Hartz Lake. No consistent ratio of track-set length to space between sets. A ratio of 3-4 common in shallow snow (front feet side by side, mostly). Degree of forward lean or toe-dig of back feet a better indicator of step length.

16FE90. Rabbit sitting on top of snow in Warrenville, IL, back yard, out of reach of anything edible, chewing cud. Bent down a couple of times to get feces for re-ingesting, taking them from anus with mouth.

16MY90. Rabbits have been eating fleabane tops.

12SE90. Watched young (nearly full grown) cottontail feeding, at close range. Eyes cranked forward, showing the tiniest bit of white at the back, as the rabbit examined and ate plants. Ate fruits and leaf blades of roadside rush and crabgrass. Seemed, however, to be using smell more than vision in checking out potential foods. I could get away with some movement when the eyes moved forward.

5JL96. Cottontails chasing each other 11a.m., picnic shelter area at Willowbrook. The chases were brief, sometimes extending into brush, but generally about 20 yards at most and often half that. They then would stop as the pursuer peeled off, but then often the chased animal approached, clearly soliciting another chase. Sometimes the chases were moderate in speed only, sometimes there were brief very fast spurts in the middle.

16MY98. Cottontail at Willowbrook eating blue violet leaves (nearby: flowering motherwort mint, garlic mustard).

28JA99. Cottontails this winter not visible during the day. Tracks indicate they are hiding in metal drainage culverts. Coyotes occasionally vainly try to dig them out or, perhaps are trying to spook them out.

10MY99. Cedar Springs, Michigan. Cottontails mating. Smaller adult chased larger, caught up, mounted and very quick small thrusts for a couple of seconds, then larger ran away and pursuit resumed. In woods clearing.

Here a mother rabbit at Mayslake covers her nest shortly after giving birth.

29AP09. Mayslake. As I drove in, I saw a rabbit digging in the lawn of the long parking lot island beside the drive. Three other rabbits were nearby, and one eventually chased her away from where she was digging and I saw him mate with her once. I thought she was still digging soil, but perhaps she was digging out grasses to cover the nest with (supported by her relative skinniness in photos). I returned at mid-day, found 5-6 babies in the nest there. Soil still beside the nest, but flattened. Babies born last night or this morning, it appears. (These rabbits eventually weaned and left the successful nest).

Winter Moths

by Carl Strang

Last year I arrived at Mayslake Forest Preserve at the beginning of November, and went through that first month without seeing any. We’re halfway through November a year later, and I still haven’t found one there, though I’ve spotted them elsewhere in DuPage County this month. I’m talking about winter moths.

Look at the eyes on that dude! Despite the slender looking antennae, I know it’s a dude rather than a dudette because the females of the species are wingless. The winter moth, Erannis tiliaria, is a member of the inchworm family (Geometridae). The adults wait until November to emerge, and I love them despite their drab color. When the males fly through the forest in that cold air, their slowed flight gives them a dreamlike, drifting quality as they pass among the stark tree trunks of the leafless woods.

Much of their adult structure seems geared to a cold-weather emergence. Females don’t waste energy building wings. Males must fly in the warmer daytime, and apparently use a combination of enhanced vision and pheromone detection (on relatively minimal antennae) to find the females.

Winter moth caterpillars are fairly straightforward, if a little more colorful than most inchworms: white beneath, bright yellow on the sides, and pinstriped brown, white and black down the back behind the red-brown head. I’ve seen them, but never with camera in hand. Like many moth caterpillars, they consume a wide range of tree species. Their other common name, linden looper, suggests a preference for basswood. That tree is rare at Mayslake, but winter moth larvae are known to eat the leaves of many trees, including oaks, which are common there. So, I continue to look for this ghostlike moth on November days in Mayslake’s savanna and brushy woodlands.

Union Township, 1830’s

by Carl Strang

Yesterday I began to recount my study of what my home township in Indiana was like in the 1830’s, before Americans began to transform it from wilderness to a predominantly agricultural landscape. Here is a more detailed line drawing of the final map.


The surveyors’ description provided enough information for me to rough out the map. Getting to the final version required another step. I acquired a soils map of Marshall County, and looked for correlations between soil types and vegetation categories as the surveyors described them. A specialist might have done it differently, but for my part I was satisfied that the correlations were good enough to draw the detailed boundaries of vegetation areas by combining the surveyors’ records with the finer-scale soils map.

Of the various communities defined by woody plants, swamps are the ones most absent from today’s Union Township. The characteristic swamp tree was the tamarack. Here is some foliage of that species, which is unusual in that it is a deciduous conifer.

Tamarack foliage b

I remember seeing a tamarack tree at the old state fish hatchery that was formed out of the south end of Moore Lake, but that tree died years ago and I know of none surviving in the township today. There are bits of shrub swamps here and there.

A relatively moist (mesic) forest occupied much of the east half of the township, on the rolling Maxinkuckee Moraine. Sugar maples and beeches were characteristic trees, though not necessarily the dominant ones. A remnant of this forest is preserved by the Culver Military Academy in its Bird Sanctuary.

Dry forests and savannas were dominated by oaks and hickories, which grew on more sandy soils. They represent a continuum, with the forests shading the ground fully in the summer and the savannas’ trees scattered enough that prairie-like vegetation grew between them. A forest of this type was the site of the town now known as Culver. Gradually over my lifetime I have noted the passing, one by one, of the town’s largest surviving old oaks that were part of that forest. Dry forests persist mainly in the many “wood lots” preserved by the township’s farmers.

I am grateful to all the individuals and organizations, from private landowners to The Nature Conservancy, who have made the commitment to preserve and restore these reminders of the wilderness that once was.

Fruits of Restoration

by Carl Strang

In earlier posts I have written about the restoration work going on at Mayslake Forest Preserve. Today I want to share some of the positive results that already are visible. The prairie was burned in late March, and as usual looked like a desolate moonscape afterward.

Mayslake burn 4b

This week that same area is green with vigorous growth.

Prairie 19MY 2b

Meanwhile, the slope between the friary and May’s Lake has greened with diverse plants.

Friary hill spring 4b

In places there are abundant oak seedlings, the potential next generation that had no chance beneath the dense buckthorn and honeysuckle brush that was cleared out over the winter. Members of both the white and red oak groups are visible here.

Oak seedlings b

In addition, Virginia waterleaf is flowering in good numbers all along the slope.

Waterleaf 1b

Toward the bottom of the hill some wild geraniums have begun to bloom.

Wild geranium b

Nearby are some Rubus which key out to common dewberry.

Common dewberry b

A red-osier dogwood was one of the woody plants carefully avoided by the brush-clearing crew, and it is flowering.

Red osier dogwood b

Earlier I showed the abundant trout lilies, toothworts, three species of buttercups, dutchman’s breeches, trilliums, violets, wood anemones and so forth. More will follow.

Gypsy Moth Egg Masses

by Carl Strang


The beautiful oak savanna at Mayslake is facing a challenge.




See the oval, pale yellow blobs on the underside of the oak branch? Those are egg masses of the gypsy moth. Here is a photo of one being produced.




The egg masses are fuzzy, around an inch or a little bigger in diameter, and can be attached to any solid object on the ground or above it. I can’t think of anything you might see in our area that could be confused with them.


The gypsy moth is not native to North America. It escaped from an ill advised breeding program in New England, and its westward spread has reached Illinois. The caterpillars eat a variety of tree leaves, but oaks have the misfortune of opening their leaves late in the spring, just as the tiny caterpillars emerge from the eggs. The expanding leaves have not built up their chemical defenses, and so oaks are perhaps the trees most susceptible to gypsy moth attack. I say “attack,” but that is a human judgment. The caterpillars are being caterpillars. They are new to the area, so their diseases and parasites haven’t caught up with them, yet. Gypsy moth populations typically build within a few years to levels where they totally defoliate trees.


As I mentioned in an earlier post about sycamore anthracnose, a single defoliation episode won’t kill a healthy tree. However, a tree already weakened by another stress, or a tree defoliated repeatedly by gypsy moths, could die. A certain percentage of the forest’s trees will be lost. Ultimately the diseases and parasites will catch up, and the gypsy moth will be cut back to a less harmful density. But they are with us for good. All these predictions are based on what has happened everywhere east of us. The forest preserve district and other agencies are doing everything that can be done to minimize the damage, but we will lose some trees.


There is some debate about what homeowners can or should do to protect their trees. Remember that I am speaking for myself here, but my bias is toward limiting the damage by manual means. There are several steps that can be taken. At this point in the season, the thing that can be done is to look for and destroy egg masses in your yard. Look not only on trees but on any objects, including the house, outdoor furniture, firewood stacks, etc., where an egg mass might have been deposited. Scrape them into a container, fill the container with soapy water, leave it for a few days, then dump the killed egg masses in the trash. Advise your neighbors to do the same. I’ll provide other steps in the appropriate seasons. We’re in for a few unpleasant years, but there will be an end to it. Mayslake should not have major defoliation this year, based on the number of egg masses I am seeing, but now it’s just a matter of time.

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