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.

Muskrat

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.).

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).

More Weeds

by Carl Strang

Time to catch up on the weeds at Mayslake, as many more have begun to bloom. Remember that here I am using a very broad definition for “weed,” that includes the meanings of undesirable plant, plant not native to the area, and plant with a weedy life history strategy . An example of a native plant in the last category is annual bedstraw.

Annual bedstraw b

The rest of today’s species are imports. Two are from Asia, and perhaps it is no coincidence that these two both had specific agricultural uses. One is alfalfa.

Alfalfa b

The only place I have seen alfalfa at Mayslake so far is in a location that once held a dairy farm, and I wonder if this plant’s history traces to that operation. The other Asian weed also very much meets the definition of “undesirable plant.”

Multiflora rose b

Multiflora rose was widely planted as a thorny hedge, decades ago. Too late people realized how uncontainable this shrub is, and I have gotten many a piercing while trying to remove it from places under my protection. The rest of today’s weed list comes from Europe, and most probably were hitchhikers. One exception is red clover.

Red clover b

Another, European highbush cranberry, is planted widely as a landscape shrub.

European highbush cranberry 2b

Crown vetch has been planted in an effort to control erosion and enrich the soil cheaply in highway construction projects.

Crown vetch 1b

Like multiflora rose, it has become a problem plant because it won’t stay put. As far as I know, the remaining European species were incidental rather than intentional imports. These include ox-eye daisy,

Ox-eye daisy b

sulfur cinquefoil,

Sulfur cinquefoil b

bittersweet nightshade,

Bittersweet nightshade b

English plantain,

English plantain b

and yellow sweet clover.

Yellow sweet clover b

So far I have not seen white sweet clover at Mayslake.

%d bloggers like this: