Muskrat Species Dossier

by Carl Strang

Last week’s literature review of muskrat population dynamics inspired this week’s choice of species dossier to share. These dossiers are limited to what I know about an animal from my own experience. I created them in the mid-1980s, writing an introductory paragraph of what I could say I had observed to that point. Subsequent dated entries expanded on that base.


Muskrats are aquatic rodents, but more closely related to meadow mice than to beavers.

This rodent lives in marshes, ponds, lakes, and streams. I have seen it in Illinois, Indiana and western Alaska. The den may be a tunnel in a bank (streams, lakes) or a cattail-mound nest (marsh). Muskrats cut runways in aquatic vegetation. They eat both plant and animal foods. One ate dead fish preferentially while recovering from injuries at the Willowbrook Wildlife Center hospital. At the Culver (Indiana) Fish Hatchery in late winter 1986, muskrats left the ponds and crawled up to the service roadway where they picked out leaves of English plantain to eat, selecting that species from a typical assortment of weedy herbs. Muskrats leave scent posts of feces on floating objects, sometimes creating a raft of cut water plants for this purpose. Their tracks are fairly distinctive. Front footprints are much smaller than hind; deep ones show a small 5th toe. Toes are relatively parallel on both front and hind feet. A tail drag mark often shows.

Muskrat tracks, the larger hind foot to left, front foot to right.

8JL73 (from field notes). In western Alaska, a muskrat observed taking Carex aquatilis into its bank nest.

2SE86. At Willowbrook (Glen Ellyn, IL), a muskrat ate a fallen (still yellow-green) mulberry leaf, and leaves + stem + flowers of Polygonum cespitosum longisetum on the bank, then cut several stems of the latter and returned downstream with them. Half an hour later, 2 muskrats, one smaller and grayer, one larger and browner with greater variation and demarcation of coloring, grazed in the same area at the ford of Glen Crest Creek. After at least 10-15 minutes of grazing, each went downstream with a mouthful of grasses. Despite this apparent episode of household establishment, this was the last I saw of these animals.

Front foot of dead muskrat. The large toenails are important digging tools.

26DE86. Muskrat 70 yards from shore in Lake Maxinkuckee at the Culver town park, diving in a small area where canvasbacks fed a month earlier. Under water 10-15 seconds, on surface 20 seconds to 2 minutes, tail lifting and turning actively. Head too low for me to see what the animal was doing, but probably feeding.

8MR87. Fresh muskrat tracks at Waterfall Glen, heading downstream in an empty streambed (Willowbrook received lots of calls last week about muskrats well away from water). The gait pattern resembles a woodchuck’s: like a diagonal walk, with front feet just behind and inside same-side hind print, and showing a definite straddle. About 3.5″ between sets of prints.

Bones of a muskrat revealed by a controlled burn. This muskrat died far from water, presumably while dispersing.

26AP87. McKee Marsh. A muskrat saw me, dove, brought its head up within a small cattail clump a few feet away to check me out. Just the top part of head was revealed, buried partly in cattails. Another was working on a mound nest at mid-morning, noisily pulling or breaking cattails near it, and repeatedly walking up to the house top with cattails in its mouth.

10MY87. McKee Marsh. One seen scratching itself while floating.

23DE87. Muskrats feeding on small branches of a large willow that fell into Glen Crest Creek within the past couple of days.

30OC89. One or more muskrats have devastated the tops of the volunteer cattails which established themselves in the Willowbrook marsh during the summer. The muskrats appeared about a month ago. Almost all leaves were cut at water surface level.

Leaves cut by muskrat.

14DE89. Willowbrook. Tracks show that a muskrat emerged from an island bank den in the marsh pond, and foraged briefly on land. It broke through the top of its burrow to do so, and resealed the breach with mud, which has frozen.

19DE89. Willowbrook. The muskrat has additional breakout spots on the island, separated by 15-20 feet.

3JA90. Willowbrook. Tracks in snow show that a muskrat went up and down Glen Crest Creek on the ice, following the same route each direction. Dragged its tail in one direction, but not the other. Diagonal walk, both, throughout. Direct register when not dragging its tail.

Muskrat scats, dry type.


Muskrat scats, wet type.

5JA90. Willowbrook. On the night before last (a relatively warm, rainy night), a muskrat burst out of the pond bank, walked along edge of the pond, then headed toward the stream. Later, it came back. Tail dragged more in the gallop gait, not so much in diagonal walk of return. It followed same route back. From that emergence spot (on main bank near island), there were other out and back paths up onto land. Tracks did go into the stream and back.

22JA90. Willowbrook. A muskrat was up on the shore of the pond at mid-day (last week’s thaw made all pond edges ice-free). It ran into the water at my approach. I could see it through the ice, swimming rapidly with skulling kicks of its hind feet (both feet kicked simultaneously, ~2-3 feet and 1 second between kicks).

Muskrat venturing onto land, Fullersburg Woods.

28MR97. 11:30pm. Muskrat at Thornewilde/Edgebrook subdivision entrance (Butterfield Road, Warrenville, IL), on road, 100 yards from nearest stream.

(I see I have been negligent in copying notes from my later observations at Willowbrook, Fullersburg and Mayslake. For instance, in more recent years I have observed muskrats diving for clams on several occasions in Salt Creek at Fullersburg, and learned to recognize the piles of empty clam shells they leave on the shores of ponds and rivers. I have seen how they manage entrances to bank dens, excavating them deeper as water levels drop. They seem to prefer mound nests, building them in the parking lot marsh at Mayslake when there was ample cattail building material but using bank nests in years when this was not the case. One winter at Willowbrook, tracks revealed how one came onto land in winter, was trapped in a culvert for a while when a coyote chased it there, and eventually made its way back to its den. I also have found where coyotes have killed muskrats. For at least 2-3 years I had a frustrating battle with muskrats at Willowbrook, building exclosures to keep them out of patches of wild rice I was trying to protect. They were persistent, revealing the ability both to tunnel beneath the fence and to climb over a vertical 3-foot barrier of chicken wire.).

Baltimore Oriole Dossier

by Carl Strang

It’s time to share another of my species dossiers. This one brings together my experiences with a bird that at the moment is to be found in the tropics. Spring can’t come too soon.

Male Baltimore oriole.

Oriole, Baltimore

This bird’s song is very loud, composed of clearly defined, sharp notes, usually a bundle of several with mixed pitches. The Baltimore oriole stays near treetops in feeding, generally. They nest in residential neighborhoods and open woods, especially beside ponds, lakes and rivers. The nest is a distinctive, unusual hanging basket, usually attached to an exposed, slender branch tip over water or a road. One spring I watched part of a nest-building, the female bringing long fibers and weaving them into a bag that already had its basic form. The stroking, pulling bill movements of the bird used the new fiber to fill a space and strengthen the bag.

Even as it deteriorates in winter, a Baltimore oriole nest is a beautiful object.

3JE86. A male foraged low in a crabapple, moving fairly quickly between perches, moving 2-3 feet at a time, looking among leaves, often burying his head among them and searching. Once he dropped to the ground in pursuit of a prey that jumped to evade him.

14JE87. Adult eating mulberries at Culver fish hatchery.

7MY88. Singing at Culver.

4MY99. First migrant noted at Willowbrook. Last spring migrant observed there 27MY.

11AU99. First fall migrant noted at Willowbrook. Last one noted 24AU.

This nest is relatively visible.

17JE00. Arboretum, Joy Path. Adult male foraging in the branch tips of a bur oak where leaves are clustered. It was searching and probing into clumps of dead leaves. It caught an adult moth, removed the wings, then flew straight to its nest overhanging the path at least 20 feet up. The moth was fairly large and heavy bodied, perhaps a noctuid. The nest is within a clump of leaves so that it does not appear suspended. Later, both the male and female were carrying food to the nest. When they were there, and for a few seconds after they left, a chorus of faint peepings was audible.

2JE01. Meacham Grove, east part. A female oriole led me to a nest that was so woven into the cluster of leaves at the end of a bunch of slender twigs that the nest was practically invisible.

There is a Baltimore oriole nest here, but it is well buried among the leaves.

16JE01. Newly fledged orioles still were close to the nest at the Arboretum, Heritage Trail. The nest was above a service road-trail just inside the fence separating the savanna area from Hidden Lake Forest Preserve, on the end of a descending oak branch’s lowest twigs. One of the fledglings was still perched just above the nest, the others were scattered on that branch and in nearby branches of other trees. They were essentially motionless for a long time, but very vocal, with distinctive calls: 3 quick identical notes that sounded like uninflected robin notes.

31AU02. A Baltimore oriole in full male breeding plumage, singing at Lincoln Marsh from the very top of a tall tree. Not full volume, and only little chattering phrases, but clear oriole voice tones, whistles. Sang for several minutes.

27JE08. Baltimore oriole fledglings have a call that is a rapid series of clear notes rising as on a scale.

2MY09. An oriole at Fullersburg was taking nectar from buckeye flowers.

4MY09. Mayslake. Series of photos of an oriole probing clusters of oak flowers and opening leaves.

Foraging oriole at Mayslake.

1JE09. Mayslake. Pair of Baltimore orioles mobbing a fox squirrel in the medium-sized cottonwood closest to the SE corner of May’s Lake. They gave frequent, loud, identical, slightly slurring notes but did not attack the squirrel. I found the nest at the end of the lowest branch on the east side of the tree, 15-20 feet up. The squirrel eventually jumped to another tree without finding the nest, escorted by the male oriole, and the female almost immediately returned to the nest.

Here is the female giving her alarm calls.

10JE09. The same pair of the previous entry is feeding a cowbird fledgling just outside their nest. In the brief time I watched, the female fed the cowbird once, the male fed it once and a nestling once.

Cowbirds and orioles are in the blackbird family.

Apparently this episode of nest parasitism doomed the orioles’ own young, as I never saw any oriole fledglings from that nest.

Black-capped Chickadee Dossier

by Carl Strang

I have mentioned black-capped chickadees from time to time in this blog, most notably when introducing the topic of mixed flocks. Today I want to share my dossier on this species. In my dossiers I try to summarize what I know of a species from my own observations, as opposed to information from the literature or other outside sources. I began writing the dossier in the mid-1980’s. Observations begin with my date codes.

Chickadee, Black-capped

Ca. 1979. I remember sitting on the hawk watch at Reineman Sanctuary in PA in fall and watching as a sharp-shinned hawk zipping along the ridge suddenly turned its course so as to enter the tree canopy and caught a chickadee.

Boiling Springs, PA, 1980. A pair nested in hollow Ailanthus branch. One bird was electrocuted by a nearby electric fence. The other completed incubation and at least began to rear the brood alone. “Cheeseburger” call (more formally known as the fee-bee call) used early as apparent territorial signal.

Lombard, IL, 1981. A pair nested in a wren house, raised a brood, then returned and raised a second brood in the same house. In both cases, the pair traveled the neighborhood with their groups of fledglings.

Maple Grove Forest Preserve (F.P.), 1986. A pair was cleaning out an old cavity in a 10 foot snag in the maple forest. The excavating bird periodically removed beaks full of sawdust. Other bird remained nearby, giving occasional “chickadee” contact call.

Meacham Grove F.P., 24MY86. For the first time, I saw a chickadee taking advantage of tortricids hidden in folded leaves. One individual moved from one folded leaf to the next, vigorously tearing them open. I expected to see it more frequently than I have, given the lack of other birds with the appropriate foraging behavior in their repertoire, and the abundance of this food resource.

Willowbrook F.P., 1984-86. Chickadees have broods in the wooded riparian strip each spring. One pair appears to control the entire 1/4 mi. X 100-foot strip. Groups of more than 2 chickadees stay together through the winter. “Chickittaperk” vocalization appears to be an interspecific agonistic (dispute) display.

Chickadees weren’t common in Culver, Indiana when I was growing up. I remember being pleasantly surprised that a pair was present, nesting, at Miracles’ house in summer. This implies they were more easily seen in winter, at the feeder. Old trees and branches were scarce in our neighborhood.

Alarm call: one used a sharp “chiburr,” another answered with the same call.

11FE87. Willowbrook. Widely scattered chickadees in the Back 40 old field are maintaining contact mainly via the feebee call.

28FE87. A group of a half-dozen chickadees in trees: much sneeze-calling and chick-chick-chick-chick, but few chickadee calls, with much chasing and displacement. Later, many individuals made chickadee calls from widely separated perches. Then a period of silence followed.

14MR87. Maple Grove F.P. Seven chickadees moved together with a mix of chickadee and sneeze calls, occasionally briefly chasing one another. The group spread out widely, then used very high-pitched brief “cheeks” for contact.

29AP87. Chickadee caught adult noctuid moth, pecked body (scales puffed into the air), removed wings one at a time and they drifted to the ground, landing at least 3 feet apart.

1JL87. Willowbrook F.P. Chickadee pecking at mulberries.

10SE87. 0.5-3 seconds per perch in foraging, flying or hopping a few inches to 6 feet or occasionally 10 feet between perches, acrobatic hanging or hover-gleaning, pecking at dried leaves, turning and lowering body almost to upside down position to peer different ways.

13SE87. At West DuPage Woods F.P., several chickadees in a mixed flock with a redstart and a bay-breasted warbler.

17JE89. A broad-winged hawk callied repeatedly, in north end of Maple Grove F.P. Jays, flickers and grackles were highly agitated, flickers the most continuously vocal with “keels” every 2 seconds (2 birds). Grackles gacking frequently, too. A great crested flycatcher near, also vocal, but not clearly in response to the hawk; same with chickadees. Robins definitely disturbed, with nervous dee-dee-dee’s every 20 seconds or so. Jays in bursts, with several birds mobbing.

10JE90. Warrenville Grove. Chickadee saw me at sit near edge of woods. Alarm call “chicka-chicka-…(rapid)-dee-dee-dee”

3JL90. Chickadee plucked 2 unripe (white) mulberries from the branches. Dropped the first, then went for the second. Worked on it several seconds, holding it against a twig with its toes. I couldn’t tell if it ate the whole berry or just extracted seeds. Suspect latter.

7SE90. 2 chickadees eating dried crabapples, eating, pulling out and eating little bites.

30SE90. Chickadee and downy woodpecker eating poison ivy berries at Ann’s business property near Lafayette.

8FE00. Chickadees heard singing for the first time of the year at Willowbrook, and continuing in the following days. Also vigorously chasing each other this day, with agonistic vocalizations.

10FE00. Chickadees singing (feebee song) at Willowbrook.

1AP00. Morton Arboretum, Heritage Trail. A mixed flock with at least 1 brown creeper, 2-3 chickadees; juncos and robin in area. Chickadees longer on each perch than golden-crowned kinglets observed yesterday. A lot of looking around, not so constantly moving between perches, and making larger jumps between perches, 3′ common. Later, another association of chickadees, golden-crowned kinglets and a white-breasted nuthatch. These mixed flocks stand out because after going through a long segment of forest path where there are essentially no birds, suddenly there are many at once of several species. Again, chickadees sitting longer in one place and moving farther between perches. All moving together in same direction through forest, and moved away from me as I observed them. Later still, a couple of chickadees without associates. Perhaps this is the kind of observation that led to the local core species idea.

25JE00. This spring I have observed 3 chickadee groups with parents and fledglings, one at the Arboretum on 1JE, one yesterday at Willowbrook, and a third in another part of the Arboretum today. Instead of being spread out, in each case the groups were clustered in a small area no more than 20 feet in diameter, and they moved only very slowly. Feedings were frequent, so apparently the parents directed or led their young to food-rich locations.

11MR01. A chickadee at Timber Ridge Forest Preserve with a variation on the fee-bee song: the “bee” syllable is repeated, and each syllable has the usual hinged quality, i.e., “fee-bee-ee-bee-ee.”

More recent observations have focused on the role of black-capped chickadees in mixed flocks.

29AU01. Algonquin Park, Ontario, Mizzy Lake Trail. Flock 1: Golden-crowned kinglets, a young-of-the-year black-throated green warbler, black-and-white warbler, black-capped chickadees. Flock 2: At an edge between mixed forest and a lake. Black-capped chickadees, several black-throated green warblers (appear to be sticking together to form their own group within the flock), at least 1 blue-headed vireo, 1 female or young blackburnian warbler, 1 chestnut-sided warbler, and 1 Tennessee warbler. The black-capped chickadees are very abundant here, the most apparently numerous birds in the forest (because of their frequent calling and frequent presence). It is easy to see how migrant birds accustomed to forming mixed flocks with them here in the north could attach to resident birds they encounter on the trip south. Flock 3: Black-capped chickadees, Swainson’s thrush.

30AU01. Algonquin Park, Bat Lake Trail. Flock 1: Black-capped chickadees, a black-and-white warbler, the latter singing. Flock 2: Black-capped chickadees, red-breasted nuthatches, golden-crowned kinglets, 1 or 2 black-throated blue warblers, at least 1 Tennessee warbler, yellow-rumped warbler. The first three species are the vocal ones. These flocks are distinctive: you go for hundreds of yards seeing or hearing no small birds, then suddenly there is one of these diverse groups in a small area.

31AU01. Algonquin Park, Spruce Bog Trail. Flock 1: Yellow-rumped warblers, black-capped chickadees, red-breasted nuthatches, golden-crowned kinglets. Do more northern birds, living in more open forests, either not have chickadees to associate with, or perhaps the scattered trees (if they are) remove the advantages of mixed flocks? See if it’s true that the non-mixed-flock species tend to be more northern.

12SE01. Willowbrook. Flock 1 around west end of cross trail. 2 chickadees and 1@ of black-throated green, magnolia, Tennessee (sang a couple times), and 1 unidentified species. Flock 2 near the NW corner of nature trail, a magnolia warbler apparently alone.

13SE01. Willowbrook. A large but difficult to view mixed flock near office building: 3 chickadees, 2 redstarts, a blackpoll warbler, a red-breasted nuthatch, and many others.

14SE01. Willowbrook. Flock 1 around NW corner of nature trail: redstart, chickadee, downy woodpecker, Tennessee warbler, black-throated green warbler, magnolia warbler, red-eyed vireo. Flock 2 between eastern part of animal exhibit and bridge. Chickadee, 3 redstarts, downy woodpecker, blackpoll warbler (it is possible that the one seen earlier joined this flock; it was near this location).

17SE01. Willowbrook. Flock 1: 3 chickadees, 1 redstart, others perhaps; near west end cross trail. Flock 2, base of savanna, 2 palm warblers only. Flock 3, brush area east of Nature Trail, 2 chickadees only. Flock 4, another part of same brush area, 2 chickadees, a magnolia warbler, 1 other unidentified.

19SE01. Willowbrook. Flock 1, east exhibit area to bridge: 2 chickadees, 1 black-throated blue warbler, 1 redstart, possibly others. Flock 2, west end cross trail: staying around berry-feeding robins, waxwings and catbird, with no chickadees around: a black-and-white warbler, 2 downy woodpeckers, a redstart, a blackpoll warbler, possibly others.

25SE01. Elsen’s Hill, plateau above river. Flock 1: at least 8 vocal, active yellow-rumped warblers, and a ruby-crowned kinglet. Flock 2, very large and diverse, only some individuals identified: 2 chickadees, black-throated green warbler, blackpoll warbler, 2 Nashville warblers (1 low in an aster thicket another in low tree branches), downy woodpeckers, a parula behaving like the Nashville, 2 redstarts, a chestnut-sided warbler.

26SE01. Willowbrook, between bridge and animal exhibit. 2 chickadees, and at least one @ of vireos (Philadelphia, red-eyed, yellow-throated), warblers (Tennessee, magnolia, parula, black-throated green), scarlet tanager, red-breasted nuthatch.

27SE01. Willowbrook. Flock between bridge and exhibit fence. 2 chickadees, 1 Tennessee and 1 magnolia warbler.

30SE01. Fox River and Island Park, Batavia. Many yellow-rumped warblers spread out all over, some hover-gleaning, some flycatching, others reaching for poison ivy berries. With them, a chickadee, a male Cape May warbler in the top of a silver maple, very active in the short time I saw it.

14SE02. Elsen’s Hill. I walked for several minutes, seeing apparently independent Tennessee warblers (2 together) and a Nashville warbler before encountering a large flock. This flock seemed to be changing composition over time, i.e., after my initial observations I walked a short distance away, then returned, and when I came back, some birds were the same but there were several new ones, as well. Later, after following the flock for 50 minutes or so and losing them in a direction I did not want to pursue in the brush, I returned to the starting point and a small mixed flock was there, with some of the birds I saw initially (apparently, none were marked of course) and a couple added ones. Initial group: a blackpoll warbler, 2 red-eyed vireos, 2 redstarts, an essentially silent chickadee, a black and white warbler, a Tennessee warbler, a Swainson’s thrush, a female or young black-throated blue warbler that was the only flock member calling consistently, all foraging in brush understory within 15 feet of the ground (the redstarts were the only ones consistently going above 10 feet; this was after 9 a.m.). Flock after my return: golden-winged warbler (like the redstarts, up higher, and very active, including flush and pursuit), a male and 2 female or young black-throated blue warblers, 2 Tennessee warblers, a black-throated green warbler, 3 redstarts, 2 blackpoll warblers, a black and white warbler, a blackburnian warbler. After it had warmed up some, later, a magnolia warbler foraging 20-25 feet up and the other birds also have gone higher. Doing a lot of reaching, and spending much time looking from each perch. At 10:45 I returned to the starting point: 4 noisier chickadees, 2 red-eyed vireos, a blackpoll warbler, a male redstart, a magnolia warbler, all except the chickadees foraging higher, throughout the tree canopies. Also a downy woodpecker, black-throated green warbler, Swainson’s thrush.

25AU08. Fullersburg Woods. First mixed flock of the fall migration has 2 chickadees, a downy woodpecker, a Tennessee warbler and a Canada warbler.

28AU08. Fullersburg Woods. Mixed flock just S of Willow Island bridge: 2 chickadees, 2 Tennessee warblers, 2 magnolia warblers, a gnatcatcher.

29AU08. Fullersburg Woods. Mixed flocks: One with four chickadees, two Tennessee warblers, a magnolia warbler and a black-and-white warbler. Also, 2 Tennessee warblers together apart from mixed flock. At mid-day a mixed flock near the junction of trails with 3 chickadees, 3 Tennessee warblers, a white-breasted nuthatch, a magnolia warbler, a parula. Chickadees were doing a lot of hanging upside down, Tennessees less acrobatic running along tops of branches and reaching, magnolia and parula more rapid movements, hopping between branches, nuthatch on bark, all in top half of canopy.

13SE08. Kettle Lakes Provincial Park, Ontario. Large, mixed flock in an area around 75 yards in diameter: at least 2 black-capped chickadees, 5 golden-crowned and 4 ruby-crowned kinglets, 4 yellow-rumped warblers, 2 red-eyed vireos, downy woodpecker, black-and-white warbler, black-throated green warbler, redstart, red-breasted nuthatch. I’m hearing white-throated sparrows, but they seem all near the ground rather than up in the trees with the others. Weak songs from ruby-crowneds, the black-throated green and the black-and-white. This is mainly an area of aspens with some jack pines. Mixed flock: at least 2 chickadees, at least 2 golden-crowned kinglets, 2 ruby-crowned, and a yellow-rump. Aspen grove again with some jack pines and a couple white pines.

15SE08. Nagagamisis Provincial Park. On trails, encountered a little flock of at least 7 ruby-crowned kinglets. Nothing up with them first time through, but white-throated sparrows lower down in that area (on the way back a chickadee, a brown creeper, 3 golden-crowned kinglets and a Swainson’s thrush added). Birds have been few, and I cannot discount the possibility of an association of the white-throated sparrows with this group. On the Time Trail, balsam fir the dominant tree with plenty of white spruces, some black spruces, white cedars, paper birches. Another mixed flock with at least one chickadee, 2 ruby-crowns, 3 golden-crowns.

21SE. Mayslake. A mixed flock at edge of Area 9 and grounds containing a black-throated blue warbler (new preserve species), black-throated green, 2 redstarts, 2 blackpolls, chestnut-sided, Nashville, black-and-white, magnolia, and a chickadee.

Mammal Action

by Carl Strang

In summer there is less to report about mammal activities at Mayslake Forest Preserve. Mammals are better able to hide in the dense green growth, most avoid coming out in the heat of the day, and the hard soil registers footprints less clearly. There are exceptions to this rule, though. Cottontails have been visible in numbers that have increased substantially since nesting began.

Cottontail 15JLb

It is well that they are so prolific, given the heavy predation pressure they face through the entire year (I shared several examples last winter, for instance here ).

Squirrels are diurnal, so they remain visible on summer days though mainly early and late. Mulberries have ripened, and become a major food for the squirrels at this point in the season.

Squirrel mulberry b

Scats indicate that coyotes and raccoons also are heavy mulberry feeders, the former taking advantage of the large numbers of the berries that fall to the ground.

Mulberry b

Speaking of raccoons, here is one that stayed out a little late in the savanna one morning.

Raccoon 1b

Probably this small adult was a mother, prolonging her hunt for food with a growing set of cubs to nurse.

Footprints attest that deer are on the preserve, but they have been able to stay out of my sight. Here, hoofprints show clearly in an area of mowed tall grass.

Deer tracks grass b

Mammals again will play a bigger role in this blog as summer transitions to fall and winter.

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.

Eastern Chipmunk Dossier

by Carl Strang


The first chipmunks began to show themselves at Mayslake in the second half of March. Today I’m sharing my dossier  on the species. The codes are my representations of dates, the day followed by my month code, finally the year. The dossier was established in late 1986 or early 1987, entries added thereafter as needed. Since this one is relatively long, I have edited out some entries that simply give date and location observations.




Chipmunk, Eastern

Lives in underground burrows; often plugs some entrances with debris. Vocalizations include “chip-chip-chip…” and chip-trill alarm “chip-chip-churrrrr.” Single “chip,” birdlike. Lives in forests and at forest edges. Also savannahs with some bushy cover. Can climb trees but usually forages on ground. Disappears for most of the winter, apparently plugging burrows. In presence of red fox (passing with another chipmunk dead in mouth), they gave a couple quick chips and were silent (MY86). I have had one “singing” while watching me.

6MR87. Newly opened chipmunk burrows in Willowbrook Back 40 the first signs of that species this year.

7AP87. Chip-trill at my approach produced response by gray squirrel: jumped onto low branch, looking alert.

10MY87. Chipmunk pursued by another, stopped with 3 high chips in a lily-of-the-valley patch within forest at North Blackwell, as the other turned back. Then the first one came out into deep oak litter and foraged. Frequently stuck head under leaves, a few times burrowed completely under. In one spot munched several invertebrates, only remains found later were part of a striped slug (1/3 of head end missing, recently bitten off). Ate at least 3 items, 2 appeared to be slugs, the other had legs.

23AU87. When running hard (e.g. crossing open space), hold tails vertical. One ate an acorn.

27AU87. Chipmunk drank from small pool: barely put mouth in water, remained still until done except for rapid fluttering of cheeks. It drank for about 20 seconds.

16AP88. Morton Arboretum. An old chipmunk’s hoard of acorns, now reduced to shells, inside the hollow root of a dead oak. The top of the root has rotted away, exposing the shell fragments.

29MY88. Hartz Lake, in woods. A chipmunk saw me move my arm laterally, gave 3 chips increasing in speed, and ran. Immediately 2 jays feeding on the ground flew up. They were 40-50 feet away.

4AU88. Willowbrook Back 40. Chipmunks active. Early estivation this year because of drought?




31AU88. Willowbrook Back 40. Chipmunk 15-20 feet up, on slender branches of a 25-30-foot-tall black cherry, cheeks full.

1SE88. Willowbrook. Active past couple weeks, sniffing over the ground and quickly climbing high into cherry trees (and quickly down, head-first), filling cheek pouches.

5MR89. A cold (20F) windy day, ground frozen with crusted snow layer, yet some chipmunks active in a firewood pile at McDowell.

12MR89. Hartz Lake. An area hotly contested by 4-6 chipmunks, in low wooded area with many fallen trunks, standing hollow stems, and brush. Much chasing, sometimes turn around and chase back. Often make squeaking calls. I stalked successfully within 5 feet, lay down with arm alongside log for a while without being recognized, but none came close enough to touch (they had pretty much settled down by then).




8MY89. A foraging chipmunk appears to find its food mainly by smell, sticks nose into vegetation with eyes closed, takes object with mouth and pulls out to eat.

31AU89. Chipmunks producing lower “chuck” call with great horned owl above.

7SE89. Chipmunk eating a small (less than 0.5″ diameter) red crabapple fruit.

28JE&1JL90. Chipmunks up in mulberry tree canopies (15 feet up) at Willowbrook and West DuPage Woods (mulberries ripe more than a week now).

Late MY90. Hartz Lake. Chipmunks foraged by nosing and digging among oak leaf litter in area of scattered trees.

30AU90. Chipmunks in cherry trees, Willowbrook.

5SE90. Willowbrook. Chipmunk tracks, clear, in fine mud. 3-lobed heel. Hind tracks less clear; pushing off harder from hind feet.




18JE91. Chipmunks on ground, Willowbrook, stuffing themselves with fallen mulberries at midday.

13SE94. Chipmunks climbing high into box elder trees and eating seeds, this week. Go out to the finer twigs, look a little clumsy but undaunted.

5AU95. On Red River in WI, mink hunting along shore. As it came close, chipmunks gave a single loud “chip” apiece and were then silent (see red fox entry, in MY86).

Summer 1999. I listened and watched daily, and did not detect a time when there were no chipmunks active. No estivation, or overlapping among individuals?

2MR00. Willowbrook. First chipmunk of the year seen.

15MR00. Willowbrook. One chipmunk chasing another.

12NO01. Chipmunks still foraging, on a sunny day in the 50’s, Morton Arboretum.

Buds as Food

by Carl Strang


Spring is a time when buds are an attractive food for some animals. Here is my most recent record, a fox squirrel eating willow buds at Mayslake Forest Preserve.




Going back through my dossiers  I find records of 3 bird species and both local diurnal tree squirrels as occasional bud eaters. The summary follows.


Goldfinch: silver maple buds (1 observation).


Cardinal: elm buds (1).


Purple Finch: silver maple (several birds on each of 2 occasions).


(Bird observations all were at Willowbrook Forest Preserve).


Fox squirrel: American elm (5 occasions), mulberry (3), box elder (3), sugar maple (3), silver maple (2), cottonwood (1), and now willow (1).


Gray squirrel: American elm (7), mulberry (1), box elder (1), silver maple (1), cottonwood (1), willow (1), green ash (1), black cherry (1), and hawthorn (1).


(Squirrel observations were from 6 forest preserves plus the Morton Arboretum).


Buds have a relatively high protein content, which presumably is the attraction, but they are protected by bud scales which may be why their consumers appear to be limited to herbivorous species with relatively strong biting capabilities. The two squirrels select similar tree species for their menus, with both apparently preferring American elm above all others. Fox squirrels in addition seem to favor maples, including box elder. All my observations range from January to May, a time when alternative, perhaps preferred foods are relatively scarce. Any generalizations in a compilation like this have to be regarded as tentative, but I will continue to record new instances and see what if anything emerges.

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