Gray Squirrel Species Dossier

by Carl Strang

For several winters, now, I have been sharing my notes on various species of our vertebrate wildlife. The main idea is to step away from the literature and other second-hand sources, and document what I know about each species from my own observations. At last I have reached the end of the list of dossiers which contain enough information to post here. There may be more in the future, as I add to the limited notes presently in unshared dossiers, but this will be the last for a while. I hope the main point has been clear: to remind you, as well as myself, to pay attention and learn from experience rather than rely on the sometimes limited or misleading second-hand reports (I shouldn’t need to point out that from your perspective, this dossier is itself a second-hand report!)

Squirrel, Gray

Gray squirrel

Gray squirrel

This species is more typical of larger forests and cities. Its relative the fox squirrel is the savanna and small woodlot species, though both can occur together (this one is not found around Culver, Indiana, however). Many notes from the fox squirrel dossier also apply to this one.

27JL77. Gray squirrels fed on unripe red oak acorns at Reineman Sanctuary, Perry County, Pennsylvania. The next day, one was eating Nyssa (black gum) seeds (discarding the fruit).

29JE86. One gray squirrel foraging on the ground in an old pine plantation at Waterfall Glen Forest Preserve, DuPage County, IL. It moved slowly (diagonal walk), nose to the ground, sometimes pushing the nose beneath the litter and walking several inches with the face thus submerged. Stopped and ate 3 small objects. Later investigation of the site revealed small oval shells with tough skins, possibly coccoons, flattened ovals viewed from side with a circular cross section, with one end neatly removed and empty inside.

20OC86. Squirrels in dense brushy old field of Willowbrook Back 40. Sounds, when alarmed, like 2-3 steps or jumps, the last louder, then quiet. Is squirrel getting to bigger shrub or a tree, jumping onto trunk then freezing and watching?

23FE87. Much renewal of nut-digging (removal) past few days (and continued next 10 days or so).

28FE87. Wayne Grove Forest Preserve. Gray squirrel stuffing itself with American elm buds in top of 8″dbh tree. Later another, also in a 5″dbh American elm. Much recent excavation of buried nuts. A third individual ate a few black cherry buds.

6MR87. Squirrel high in a black willow, cutting twigs 4-12 inches long and carrying them one at a time to the top of a major 3-branch crotch high in the tree, where it was stuffing or sewing them into a mass of them.

7AP87. A gray squirrel on the ground responded to chipmunk’s chip-trill at my approach, jumping onto low branch and looking alert.

28SE87. Lots of them on the ground in Willowbrook old field. Old and young of year, both.

23JA88. McDowell Forest Preserve. Gray squirrel dug up shallowly buried hickory nut, cutting a 1.5′-tall elm to get face in close for leverage in digging. Carried nut into tree, spent about 4-5 minutes consuming it, then ate snow off top of branch it was sitting on (about 1′ worth, a powdery, thin 0.5″ wide), went down tree and continued. Paused and looked back at me.

20MR88. A gray squirrel at Meacham Grove gathering dry leaves from ground, stuffing them into its mouth with its paws then taking them into cavity nest up in old white oak. Also gathering from among the few leaves still attached to the tree itself.

10AP88. Touched a squirrel at Hidden Lake Forest Preserve (tips of his tail hairs as he “hid” on the other side of a tree trunk barely too big for him to look around).

17AU88. A chase between squirrels, apparently not play. Gray squirrel pursuing a larger fox squirrel, which jumped out of trees twice from 15-20 feet up, landing hard, to escape (in the second jump it leaped out, seemed to sail a bit, and its fall was partly broken by a small shrub). The fox squirrel uttered a harsh call, short and sharp, like part of a mobbing call, on 2 occasions. There was an un-play-like seriousness about the pursuer.

27MY89. Young gray squirrels very curious, approach when you hold still (yesterday in the park at the Newberry Library in Chicago, today in Maple Grove Forest Preserve). They have a buzzing call, precursor of the adult’s bark.

22JE89. 2 gray squirrels eating red (not quite ripe) mulberries at Willowbrook. The berries began to ripen the previous weeks, so many other ripe ones were available.

29AU89. Many twig ends, some more than 1 foot long, cut from a sugar maple in Back Yards exhibit by Sciurus sp. The twigs were laden with developing new seeds, but only a few of these were eaten. Happened in last 24 hours (lawn mowed yesterday). No nest visible in nearby trees, and this tree 25 feet from edge of lawn, similar distance from nearest other tree.

3SE89. Gray squirrel youngster (from spring litter) passing through yard, east to west (not a neighborhood where squirrels lived).

20MR90. Gray squirrel chased fox squirrel away from Willowbrook crow cage area, then came back (note: squirrels often enter Willowbrook cages to take food from dishes. A squirrel nest has been found in the bullwinkle in that cage).

22AP90. Winfield Mounds Forest Preserve. 2 gray squirrels eating enlarged cottonwood buds high in the tree. They ascended together, the larger almost seeming to pursue, certainly to follow, the smaller. The smaller climbed in 2-foot spurts, the larger following, beginning its move as soon as the smaller’s ended. Larger flicked tail in rippling pattern reminiscent of fish or salamander courtship. The smaller may have done so once or twice, but less forcefully. Slow and deliberate, not a rapid play chase. When they were high up, it appeared the smaller would leap to another branch to escape. Larger broke off chase, and they fed. Didn’t take every bud, examined many without taking. Later, larger followed smaller to ground, then up another tree, same way. Larger sometimes sniffed where smaller had been. Larger got ahead of smaller and turned to face it, flicking tail. Smaller turned away. Etc.

1JL90. Gray squirrel in mulberry tree, feeding on ripe berries, West DuPage Woods.

26JA92. Hidden Lake Forest Preserve. Lots of nut digging by squirrels, last 24 hours. Fresh snow, overnight low 20F.

21SE97. Gray squirrel eating gilled mushroom cap, Petoskey State Park, MI. Both gray and black individuals common. One chased by red squirrel briefly.

4MR99. At mid-day a gray squirrel emerged from a hole in a large, dead willow across from the Safari Trail/Glen Crest Creek junction at Willowbrook to drive away an approaching fox squirrel. The gray immediately returned to the hole.

27OC99. Fox and gray squirrels active. 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. Gray squirrels on ground this morning, some in woods, at least one in base of savanna finger at Willowbrook.

28OC99. Gray squirrel with nut, 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 ground.

9FE00. Gray squirrel using an exposed (though low) leaf nest at Willowbrook.

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

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 ID 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. A gray squirrel carrying a walnut, in vicinity of trail willow den (have seen a squirrel eating a walnut near there recently).

11JE00. In a morning’s hiking south of Langlade, WI, 1 gray squirrel seen.

21OC05. Willowbrook. Gray squirrel, tail curled over its head, giving its growling-snarling-whining call with an education raptor volunteer holding a red-tailed hawk on a glove nearby. Squirrel holding still, oriented so that its right side is toward the hawk.

25JA06. Fullersburg. 2 pairs gray squirrels chasing one another, probably courtship.

10JL06. Gray squirrel eating ripening hackberries, Fullersburg’s Willow Island.

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

Nashville Warbler Dossier

by Carl Strang

How do we “know” what we “know?” It occurred to me back in the 1980’s that much of what I “knew” about most species of animals and plants was information I had gained from reading or from talking with others. I made the decision to assemble a dossier for each animal species, based entirely on my own experience. This was humbling, as the resulting files were small even for common species. From then on I made a point of adding notes as I focused on accumulating more such experience. In recent years my attention has been focused more on singing insects, and so I have added fewer notes to the vertebrate dossiers, but such as I have I continue to share here from time to time in the winter. Today’s focus species, the Nashville warbler, is one we see in the Chicago area only during migration, so at least I have a ready excuse for its small dossier. The odd prefixes for each entry are my date codes.

Nashville Warbler

Nashville Warbler

Nashville Warbler

Observed as a migrant in Lafayette, IN, and at Willowbrook Forest Preserve, DuPage County. Song close to Tennessee warbler’s. First part of song identical, with loud “se-bit’, se-bit’, se-bit’” then instead of emphatic “tee’s” has fewer, slurred, robin-like notes (usually 3). The Willowbrook birds hung around the taller thick shrubs at the edge of the riparian strip.

1MY87. At Willowbrook, a Nashville warbler hopped along and between twigs, 8-15 feet up in riparian woodland. At times very frenetic impression, jerking head around to look in all directions and not pausing long. At other times paused for several seconds and looked all around. Caught 2 small caterpillars within 3 minutes, both by reaching into expanding leaf tufts in box elders. Killed with pecks before swallowing. Not observed to hover-glean or sally.

4MY87. Abundant. In addition to song, a “bick” call, loud and sharp. Another one observed feeding in same way as the one above: much looking between short frenetic hops, and stretching to reach prey from leaf-clusters. Feeding in box elder.

5MY87. Has a chunky body and shows fluttering-hopping advances like a kinglet.

2MY88. First of year singing. Also 7MY at Fulton County Museum property.

19MY88. Female seen at Willowbrook.

31AU88. One observed in Willowbrook riparian area, feeding among low shrubs. Acrobatic, and an aerial pursuit. Reached a lot, too.

29AP89. Heard singing at Von Oven Scout Camp, Naperville.

8MY89. Last noted of spring.

29AP99. First of season noted at Willowbrook. Last noted 14MY there that spring.

3MY99. At Willowbrook, foraging 20 feet up in a box elder. Deliberate, making 1-2-inch hops with much looking around and reaching but no acrobatics. No long jumps, except when moving from tree to tree. Sang infrequently. Slow motion not conspicuous.

2SE99. First migrant of fall noted at Willowbrook. Last seen there 17SE.

1MY00. First migrant heard at Willowbrook.

24SE00. A couple in the Sparrow Hedge, Fermilab.

13OC00. A single, clearly marked adult among Tennessee warblers feeding in tall goldenrods, etc., at McKee Marsh.

14SE02. A single individual at Elsen’s Hill (there were mixed flocks elsewhere) systematically moving from one tall goldenrod to another along a wooded trail edge, perching in or adjacent to the flower heads and searching them closely.

8MY11. Elsen’s Hill. One foraging among the twig tips of a small rosaceous tree in which leaves were expanding. It cranked and twisted its neck so as to peer into and all around the tips while remaining perched in place.

Beaver Species Dossier

by Carl Strang

The species dossier idea came from my realization in the 1980’s that much of what I “knew” about wildlife came from the scientific and popular literature rather than personal experience. I went species by species, writing what I could remember about each one from memories of my own observations. Then I built the dossiers with added notes. The dossier begins with the initial paragraphs, followed by notes dated by a code that uses two-letter combinations to signify months.


Beaver, Salt Creek at Fullersburg Woods

This aquatic rodent lives in ditches, rivers, and lakes. Observations to date have been in the Culver, Indiana, area (Maxinkuckee, Tippecanoe, Yellow River, Fish Hatchery), southern Ontario, and DuPage County, Illinois. The signs are seen much more often than the animals themselves; they are crepuscular/nocturnal for the most part, although the Canadian ones occasionally appeared in daytime, and I have seen them during the day in northern Lake Michigan and the West Branch of the DuPage River (mid-winter). Alarm signal: dives noisily, augmenting the splash with its flat tail.

Stand-alone lodge, Canada

They feed on bark and twigs of willow and other woody plants, storing large underwater piles of branches in fall for winter use. They also stripped bark from the 1-4″ diameter X 1-3′ long sticks used in building dams and lodges. The den can be in a bank or in a stand-alone built lodge. Bank dens are used in larger, deeper rivers and lakes, although built lodges also can be seen in such places. I have seen built lodges in Canada, Lake Maxinkuckee (Venetian Village), DuPage Co. (e.g., Churchill F.P.), Isle Royale. They have a distinctive appearance because of the white sticks, though some lodges on riverbanks are not rounded and so at first glance resemble piles of drift from the last flood. Mud also is used in construction. Lodges have been 8-15′ in diameter, 2-4′ high, usually on a bank.

Beaver dam, Tri-County State Park

Small streams may be dammed to create a pool (the most ambitious dam I’ve seen was on the West Branch of the DuPage River at Blackwell in mid-winter). Dams, like lodge coverings, are built of stripped sticks, mud, vegetation, usually have a slight U-shaped bend pointing downstream, and are not particularly high above the contained water level, though some on Isle Royale were taller than me on the downstream side. Very long dams can have a more sinuous shape; I’ve seen them more than 50′ long.

High beaver dam with trail, Canada

Beavers will carry branches from other bodies of water to the home pool. Cut trees are distinctive with large tooth marks and pointed (cone-shaped) ends. Beaver tracks are large, and have the rodent formula (4 toes front, 5 back), the webs of the hind feet not always making noticeable marks.

Beaver front footprint

31AU86. Beavers at Culver’s fish hatchery have reinforced the base of their dam with a heavy plastering of marl.

18DE86. Month-old beaver sign, Willowbrook Back 40: several black cherry trees had their bark chewed off on the stream side of the trunk. No others in the vicinity (willow, box elder) were damaged.

11JA87. At the mouth of Sawmill Creek, Waterfall Glen F.P., beavers this morning fed on bark of a box elder 7″ dbh, they had cut down earlier. They had made a trenchlike single path in 6″ snow between stream and trunk.

8MR87. 2 ash trees 8″dbh cut down but only some bark removed from trunk. Otherwise untouched, for months.

Beaver-felled tree, Fullersburg

28MR87. Beavers at Waterfall Glen cut three 8″ dbh bur oaks, ate much of the bark from 2 of them, in an area with much willow.

23JA88. McDowell F.P. Beavers built a long winding dam on Ferry Creek, 20-30 yards long

15MR90. McDowell. Beavers were active in the evening dark during my night hike program. We heard one chewing: identical to the sound of a squirrel gnawing a nut, and as rapid, but much louder. Several of us shined lights on it. It was on the opposite side of the river, standing up on its hind feet, against the tree. After at least 30 seconds of being illuminated, it abruptly ran into the river. It swam for another 20-30 seconds, still in lights, then walked up the bank back to the same tree, and resumed gnawing. The alarm splash is like a big rock being thrown in. I didn’t detect a tail slapping component.

13NO99. A beaver dam has been built across the very low West Branch of the DuPage River, Elsen’s Hill at the eastern horse ford.

29MR00. While running past the borrow pit at McDowell Grove Forest Preserve, I frightened a beaver into the water. It swam under the surface for 20 feet or so, a stream of bubbles revealing its position, then surfaced. Immediately it dove again, but as it did so I saw it deliberately lift its tail and slap it on the water. I could detect the sound of it, but the splash made by the posterior part of the body (spread feet?) was the louder sound. Perhaps the double sound makes it a communication for beavers, to distinguish it from other splashes.

11MR01. A beaver lodge is on the shore of the old gravel pit on Timber Ridge Forest Preserve (at the intersection of County Farm and Geneva Roads). There has been much recent gnawing of nearby woody plants.

8AP01. At around 8:30 a.m. at Red Oak Nature Center I heard a gnawing sound down near the edge of the Fox River. It was a beaver, sitting in the shallow water and feeding on the twigs of a shrub or small tree overhanging the river (intervening brush too thick to get an ID of the plant). The beaver was reaching up, biting off a branch, then consuming the twig. Less than about 3/16″ in diameter, the twig was consumed by the beaver holding it like a piece of stick candy and nibbling on it with gnawing sounds reminiscent of a squirrel working on a nut but more rapid. After 2-3 seconds of biting off the end, the beaver chewed with its molars for a few seconds, swallowed, then worked on the end some more. When the diameter of the remaining twig became greater, approaching 1/4″, the beaver turned it sideways (always holding it in the front feet) and quickly stripped off the bark.

22OC01. Beavers have been very busy in recent days at the marsh beside South Blackwell’s Heron Trail (marsh full of water thanks to heavy rains in recent weeks). They have trampled a path through the cattails all the way to Heron Trail, and have been cutting the small willows and cottonwoods into pieces, eating the bark from some of the bigger chunks, and hauling the tops into the water (drag marks visible in the mud).

6JL07. Fullersburg. A beaver swimming up the main channel along Sycamore Peninsula went to the shore at 8:30 a.m. and ate some root bark and twig bark from American elms. It continued upstream past the Visitor Center.

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.

Brown Creeper Species Dossier

by Carl Strang

This week I am sharing my species dossier for the brown creeper, a species which seems increasingly to be present in DuPage County through the winters in recent years. I wrote the initial paragraph in 1986 as I established the dossier, then added observations with their date codes.

Brown Creeper

Observed during migration in DuPage Co., sometimes all winter there and in Culver. Latest spring observation 13AP86 [April 13, 1986]. When foraging they commonly fly to the base of a tree and work their way up, climbing on and searching the bark. Often when changing trees they produce a high-pitched cheeping contact call as they fly.

1AP87. First of year seen at Pratts Wayne F.P.

12MR88. First of year at McDowell.

28AP88. Migrants still present.

14AP89. Creepers at Hartz Lake.

18AP90. Creeper on 6-inch box elder at Willowbrook.

31JA99. First of year at McDowell.

1AP99. Willowbrook’s first of year. Also seen there on 5AP.

1OC99. First fall migrant at Willowbrook.

26MR00. Several observed at West DuPage Woods Forest Preserve. All but 1 foraging selectively on white oaks, flying to within 3 feet of the ground on the main trunk and working up it, staying on the shaded side (sunny afternoon) and within an 8-inch width, mainly going straight up even over bumps. When up in crown, fly down to base of next tree. High-pitched contact calls similar in pitch and tonal quality to those of golden-crowned kinglets. One paused to preen body feathers on anterior part of body, remaining perched on vertical bark while doing so. The only one on another species of tree was on a black cherry. During the brief time I watched, it both came into the sun briefly and exceeded the 8-inch path width.

27MR00. Willowbrook. A number of golden‑crowned kinglets and 3 brown creepers observed. Kinglet contact notes usually more emphatic, in groups of 3 or 4. Creeper notes similar in pitch and tone, but a little fainter, more drawn out, and single notes evenly spaced as the bird flies between trees (spacing a little greater than the notes of the kinglets).

31MR00. Waterfall Glen. Brown creepers feeding along Sawmill Creek, with golden-crowned kinglets and a couple white-breasted nuthatches nearby (essentially a bird desert for more than half a mile until I reached this point). One feeding on a 6″dbh hackberry, going straight up the shaded side (sunny afternoon). Either the same bird on several similar sized hackberries, or several birds on same, always staying shaded side except for brief moments in the sun. When that happened, though, the creeper quickly returned to the shaded side of the stem. Once a creeper paused briefly, made a flycatcher-like sally from the bark into the air, reached with its head and beak at the turn-around point, then returned to the same point on the stem it had left. Flew out 3 feet or so. Another creeper was moving up the shaded side of an 18″ white oak, every few seconds reaching its bill to the bark and then making eating motions. Another creeper on a 12″ forked tree spent some time on the sun side (= side toward creek) of one fork, but the other larger fork was shading it.

1AP00. Morton Arboretum, Heritage Trail. A mixed flock with at least 1 brown creeper and 2-3 chickadees; juncos and robin nearby. Overcast day, no shaded side, but creeper still mainly going straight up the trunk. When defecating, lifts tail high, bending it well over back. When searching, doesn’t probe but rather peers, looking into crevices and going to different angles to do so as needed. Song “tsee-er-tser-tseree,” quick, high pitched like call but not as thin, sweet and musical tone. On a white oak, spiraled up a high 8″ branch.

13AP00. Willowbrook. 1 brown creeper observed.

13AP07. Brown creeper vocalizations include a rough call similar to that of cedar waxwing, faint thin high pitched notes given singly, and several such notes given in quick succession and similar to those of golden-crowned kinglet but a little fainter and more irregularly spaced.

2JA08. First creeper of the year, at Fullersburg (two stuck around for weeks afterward).

29AP08. Last creeper of the spring, at Fullersburg.

21OC08. Fullersburg. First creeper, fall migration.

29JA09. Mayslake. First creeper of the year.

25FE09. Mayslake. Another creeper, after a space of nearly a month, suggesting midwinter wandering.

25MR09. Mayslake. Another month between sightings.

21AP09. Mayslake. Final creeper of the spring at Mayslake (often present in past month)

29OC09. Mayslake. First creeper of the fall migration.

8JA10. Mayslake. Creepers seen in two locations.

1FE10. Mayslake. Another creeper, after a space of nearly a month.

19MR10. Mayslake. First spring migrant creeper.

13AP10. Mayslake. Last spring migrant creeper.

13OC10. Mayslake. First fall migrant creeper.

American Robin Dossier

by Carl Strang


Today’s post is another in my series of species dossiers. It begins with the summary paragraph written when I established the dossier in late 1986 or early 1987. I have edited out some less informative entries.




American Robin. Familiar bird of natural and artificial savannas. Primarily a summer resident, although small numbers remain in northern IN and IL around fruit-rich areas as long as winter weather is not too severe. Waves of migrants seen each spring and fall. Nest typically on branches of broadleaf trees, or in shrubs. Nest of grasses and mud, with deep inner cup. Sometimes grasses dipped in mud before delivery to nest. Eggs deep sky-blue. Young may get out of nest a short distance a couple of days before fledging, but after early-morning departure from nest they tend to travel some distance and do not return. Young scattered, tended individually by parents, who swoop and may peck at people or mammals which approach the young. Fledglings have dark spots on breast. Worms and insects hunted on ground in summer; fruit the winter food. Mulberries eaten by both adults and young in early summer. Winter berries include buckthorn, mountain ash. Song dominates habitat in early morning and dusk. A musical series of phrases, each composed of 2-3 clear, slurred whistling notes sung from mid to high perches in trees, on aerials, etc. Alarm call “cheet’-der-der-der-der.” Occasional battles, presumably territorial, take place. Striking white spots on tips of tail feathers may be “follow-me” signals. Preyed upon by cats, on occasion. When hunting worms, run 2-20 feet over the ground, stop, then may move a short distance, lean down with side of head turned toward Earth, then possibly reach down and pull up worm with beak.

26AP80. Pennsylvania. Robins, when startled into flight across the path of an approaching car, appear to use body-twisting and turning tactics more appropriate to flight from a hawk.

14JE87. Young-of-year eating mulberries at Culver Fish Hatchery.

9SE87. Large flock in Willowbrook Back 40. One ate grapes.

16SE87. In the evening, within a half-hour before sunset, robins were migrating south over Willowbrook. They flew just above treetop level, in flocks of 3-30, occasionally perching to rest for a time in the treetops, then moving on. The birds occasionally called to one another in flight, alternately flapping in short bursts, and gliding.

29AP88. A robin on a nest at Pratts Wayne Woods Forest Preserve, 6 feet up in crotch of a 15-foot, 3″dbh fencerow box elder.

7AU88. Young robin, apparently independent but still with spots, eating black cherries in Willowbrook Back 40.

30AU88. Lots in Back 40, mostly on ground but 1 in black cherry going after fruit.

5OC88. Robins eating grapes, Back 40.

6OC88. Robins eating gray dogwood fruits, Back 40.

12OC88. Robins eating honeysuckle fruits, Back 40.

17JE89. A broad-wing calling repeatedly, in north end of Maple Grove Forest Preserve. Robins definitely disturbed, with nervous dee-dee-dee’s every 20 seconds or so.

28AU89. Robins eating gray dogwood fruit, Back 40.

21OC89. Robins eating buckthorn berries, West DuPage Woods Forest Preserve.

3JA90. A robin singing very softly at Herrick Lake Forest Preserve. Temperature ~40F, sun.




14JA90. A large robin flock, scattered in woods on ground, moving as they do when hunting worms. Ground frozen. Saw occasional reaches to turn over a leaf, but no feeding.

7AP90. Robins in forest at Winfield Mounds Forest Preserve, throwing leaves with beaks to find food.

2JE90. Culver. A robin foraging on lawn (20 feet from nearest shrub) singing, 7:30am.

14SE90. Willowbrook, robin ate a couple small grapes, swallowing them whole.

JA99. Robins present on Willowbrook preserve all winter. Heavily fruiting asiatic bittersweet (Celastrus vine) a particular attraction.

6FE99. At Morton Arboretum, in an area thick with honeysuckle beneath a mesic forest, many robins feeding on the ground, vigorously throwing leaves aside and eating very small things too quickly to identify. I dug, found a mix of insects and fruit-like items.

9SE99. 2 robins eating buckthorn berries at Willowbrook.

13OC99. Robin occasionally singing at Willowbrook.

8FE00. Robin eating buckthorn berries at Willowbrook. They are fewer and more intermittent than last winter, 1 or 2 at most at any time.

13AP00. Willowbrook. One robin chasing another in the savanna. Could robins have nested in prairie savannas in years when fire burned off the tall plants beneath the trees? They might have fledged an early brood before the new plants got too tall for them.

16AP00. Willowbrook. A robin carrying nesting material.

1JE00. Arboretum. Along the Joy Path, a robin was perched in the lower branches of a maple, well concealed from above by leaves, sitting absolutely still and barely opening its beak at intervals to give a high-pitched note, somewhat waxwing-like but louder, better defined, that was difficult to locate.

15JE00. Arboretum. Near Parking Lot 7, when I arrived around 8am, 3 robins were giving the high‑pitched thin call repeatedly, and the forest otherwise was relatively quiet. After 10 minutes, a Cooper’s hawk started calling nearby, then flew out away from the forest edge until an eastern kingbird started to chase it. It immediately turned around and flew back the way it had come, and kept going. The robins then were quiet.

16JE00. Willowbrook. In the afternoon, a Cooper’s hawk perched near the west edge of the prairie, drawing alarm calls from a robin (the hawk‑whistle warning call) and a cardinal, and a chorus of 7 loudly mobbing jays.

5JL00. Willowbrook. Many robins, adult and first‑year, on the preserve today. A young one, and also a red‑bellied woodpecker, sally‑foraging for insects, possibly flying ants, from the top of a tall dead tree near the stream. (One passing insect was observed for a few seconds before the robin flew out and caught it).

11MR01. A robin singing loudly, Timber Ridge Forest Preserve.

28JL01. A newly on-its-own robin chased a cicada through the air, the insect giving its predator-discouraging call, but broke off the chase and flew back the way it came. The robin was never close to the cicada during the part of the chase I saw.

13MR02. First morning of robin (or any) dawn chorus at my house.

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