Blob Tracking

by Carl Strang

The title for this entry is not a technical term. It simply refers to the interpretation of tracks that are blobs rather than well-defined footprints. The mix of rain and snow we experienced on Monday provided a good opportunity for this practice. Here’s an example from the south savanna at Mayslake Forest Preserve.

What do you make of these blobby footprints?

Here an opossum was walking, left to right in the photo. As usual, the oddly shaped hind foot with its enormous big toe is turned sideways. The more uniform toes of the front foot are widely spread. The left-hand pair of blobs were made by the right feet, the middle pair by the left feet, the right-hand pair by the right feet again. You can see clearer reference examples in my tracking primer here.

I was interested to see that a raccoon had circumnavigated May‘s Lake Monday night, with various side trips into different woodlands, up and down a few trees, etc.

Do you recognize these as raccoon tracks?

The blobs in this case are recognizable as raccoon tracks because of the side-by-side pairs of footprints, indicative of the raccoon’s distinctive pace gait. Their size and spacing are consistent with the raccoon’s body size. Raccoon activity was especially concentrated in the west end of the south savanna, not far from the former friary, and the footprints had merged into the distinctive trails formed by the big flat feet of raccoons when they travel a route frequently.

Raccoon trails are easy to see in winter.

I suspected the raccoon’s den must be in this area, and sure enough, the trail led to a concrete culvert that empties into May’s Lake.

The trail comes to the culvert from the left and enters along the left edge.

In contrast to the blobs that the raccoon made during most of its excursion, it left very clear tracks as it entered the culvert. The animal still was inside, as there were no exiting tracks.

If you look closely you may be able to see a few clear footprints on the trail.

The possibility is open that more than one raccoon is involved, and that the one in the culvert was different from the one that went around the lake. This may seem a strange choice for a den, but it’s secure, and probably dry enough this time of year. I wonder if this might be the raccoon that used to live in the friary. That animal, evicted by the demolition, had grown accustomed to denning in a human structure. The concrete culvert might seem a more comfortable new home than a hollow tree.

Today’s final example had me fooled at first. This animal was doing a lot of its travel with the bound gait, and my interest in the mink had me thinking I had found a mink’s trail.

These sets of four tracks are in a pattern typical of the bound gait.

Again, you can find a description and clear photo of a mink’s bound gait pattern at the post on gaits. Eventually I had to abandon my initial idea. These footprints were too small and narrow, the sets of tracks were too close together for such shallow snow, and this animal was spending a lot of time downshifted into a diagonal walk.

The animal in question was slowing to a diagonal walk gait whenever it entered taller vegetation.

It doesn’t happen that often in mid-January, but a skunk had come out and covered a lot of ground Monday night. The temperature was in the 20’s that night, the warmest of the month, so it was not so far out of the realm of possibility. Still, it merited an entry in my skunk dossier.

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Mink Dossier

by Carl Strang

 

Last weekend I paid a visit to Fullersburg Woods Forest Preserve. I was surprised to find mink tracks, representing at least 4 individuals, all over the preserve. In the three years my office was there I had seen tracks only once or twice per winter, with only one individual in each case. Today I thought I would share my entire dossier  on that species. Here’s a photo of the critter, then on to the dossier.

 

212-mink-1b

 

We saw them frequently in daytime when floating the Tippecanoe River in Indiana when I was a child. Usually they ran along the shore or appeared in drift snags. Occasionally one dove under the water. I first identified the tracks at Fullerton Forest Preserve in 1985. Five toes each foot, very round appearance in sand or mud, larger than one would expect for the size of the animal (paddle feet for swimming). Winter tracks in snow at McKee Marsh, Blackwell Forest Preserve, early 1986: nearly all in trot or lope patterns (actually a bound with offset feet). Dropped to straight bound once when passing through an area of deeper (6-8″) snow.

25MY86. One observed traveling through a small, cattail-choked waterway at Herrick Lake Forest Preserve. Moving, body seems to flow, even on dry land. It saw me, turned around, and after going back upstream 10 yards or so climbed back over the embankment that separated the smaller waterway from a larger marshy area.

28NO86. At Culver Fish Hatchery:

 

mink-track-drawing-1b

 

11JA87. Waterfall Glen Forest Preserve, Sawmill Creek near mouth at Des Plaines River. Mink dug leopard frog up from somewhere beneath trunk of fallen tree resting on bank. Mink carried frog on a twisting path before digging hole in the 8″ snow and depositing the frog without filling hole. Frog not yet frozen, tracks very fresh. Tracks restricted to area around that tree, with many burrow-like holes entered. Mink has shelter there or else emerged from and entered river under tree roots.

21JE87. Tracks crossing muddy road at Herrick Lake Forest Preserve. Photos: in first picture, left track 1.125″ long x 1.25″ wide, right 1.375 long x 1.25 wide. Stride ~13″ in bound. In second picture, front? definitely smaller, hind? aligned more with previous set. If front’s supposed to be larger, animal turned right. In drawings, #1 1.125W x 1.25L; #2 1.25W x 1.125L; #3 1.25L x 1.125W; #4 1.25W x 1.0625L.

 

mink-track-drawing-2b


27JE87. I was picking chickweed in a rank patch at McKee Marsh at about 9am as a mink passed. It was so buried in the chickweed I thought it was a woodchuck, but it seemed to be shaking plants less and making less noise than I would expect, and moving faster. Caught glimpse of its hindquarters and tail. Had passed within 5 feet of me as I stood still. Was moving toward woods, away from marsh, ~40m from marsh.

16JA88. In shallow snow over ice of river, mink did much bounding in travel (mostly). In bound may lead with one side so that some tight “lopes” are actually bounds. Several photos to illustrate this, after fox trot photos. Photos of mink gallop. Sets 2 feet separate, and each set well spread out (bounds on the same ice were 16-18″ apart).

17JA88. See meadow vole entry.

23JA88. McDowell Forest Preserve. Mink trail wound in and out of fence row along edge of brushy/small tree area and grassy field, with some sorties into either but no more than 10m from boundary. Once went down burrow, once apparently slid on belly. Last photo on roll shows separate front and hind feet (otherwise mainly bounding with hind feet landing on fore). FF ~1.125 x 1.125, HF ~1.5 x 1.25W. Entered and exited several more holes. Eventually went into the river. These tracks were made early last night: some in water that later froze; also, I had noticed crystals had formed in tracks, when I tried to blow snow away. Backtracking: had climbed into low (3′) crotch of large willow, crossing to the other side before jumping down. A tangle of trails where a very small stream (6″ wide) flows into river. If the mink I had followed went no farther, its evening home range included ~0.25 mile of shoreline and inland up to 100m.

I picked up another trail consistent with age of first, and followed it back inland, through logs, in and out of holes, etc., until it led to where mink had pulled out of water, on other (N) side of parking lot. Toward end, at least, mink mostly led with left side, though it sometimes led with right.

13FE88. I spotted mink tracks from U.S. 31 between S.R. 110 and Rochester, IN, got pictures. Had tunnels and slides.

 

mink-hieroglyphics-b

 

15JA89. A mink at Herrick Lake Forest Preserve was dragging something, sometimes leaving only a thin mark atop the bounding set, sometimes a wider (3/4″) mark that was continuous between and over sets. The mark was on top of the tracks, therefore following them, but was on the right side while the hind feet were on the left, implying that the marks weren’t made by the tail. (See red fox 19DE89). Last month at McDowell, I found where a mink had apparently dragged something for a considerable distance, but this time the dragging was continuous and the heavy mark was more than an inch to the left of the bounding tracks. In both instances the animals were moving along the edge of a frozen lake, on the ice.

6JL90. At Hidden Lake Forest Preserve, the largest mink I’ve ever seen, moving from a perennial-old field area backed by forest into the new large marsh area.

5AU95. Red River, WI, near kayak put-in. Mink hunted along shore, on land, within 8 feet of water, moving downstream. Sniffed ground, looked into vegetation. Sometimes stopped, sometimes diagonal walked, sometimes bounded, covered 150 yards of shore before it caught a large crayfish and carried it inland. Chipmunks responded as they did to red fox at Arboretum.

8AU98. Red River, WI. Across from lunch area at first drop: beneath a group of river’s edge white cedars was an old stump with a 4″ hole. Nose of my boat touched a foot away from it, and a mink’s head appeared. I sat still and watched it for more than 3 minutes. It mostly sniffed, looked around, yawned a couple times, stepped its front legs out to sniff my boat, ducked back in a couple times.

30OC99. Dead mink, not dead too long, red blood still around mouth but no other sign of damage, on a mudflat near a stand of cattails at Fermilab. Internal injury, or self-biting during convulsions associated with illness?

21FE99. In the 3 days since the last snow, no mink tracks at McKee Marsh. Was the dead one at Fermi last fall the sign of a diseased, crashing local population?

14OC00. A mink seen at Fermilab, not far from the location of last year’s dead one. 80 yards from water, in upland old field.

31AU01. Algonquin Park, Ontario. A small one, probably an adult female, using the boardwalk of the Spruce Bog Trail, in the bog, to travel on. I was standing still, she did not notice me until 15 feet away, then turned around, went back a few steps, and got off the trail into the bog, disappearing quietly into the dense vegetation. When hunting, she sniffed frequently, and occasionally looked to the side.

20AU05. A mink and I startled one another in the early afternoon as I walked the pond in my dragonfly monitoring route at Songbird Slough. It made a brief loud squalling sound as it turned and ran away, a sound very similar to that made by a complaining juvenile raccoon.

4SE06. A mink visited my camp on the last night of my Georgian Bay sea kayak trip. I was able to get some photos.

 

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14FE09. Fullersburg. Mink tracks are all over the preserve on the morning after a 1” fresh snow over bare ground. There appear to have been 4 individuals active last night: 2 traveling together between Sycamore Peninsula and the York Road bridge, one on and around Willow Island (on both sides of Salt Creek), and one in the west part of Butler Woods. This is in marked contrast to the rare observations of single individuals at Fullersburg over the past three years. Recovering from decimation by disease?

Tracking Story: Sawmill Creek Mink

by Carl Strang

 

This snowy winter brings to mind an experience from several years ago. I was at Waterfall Glen Forest Preserve, wading through snow to follow the informal trail along lower Sawmill Creek between the railroad tracks and the Des Plaines River.

 

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I came across some fresh mink tracks, and they were unusual. Can you see why?

 

 

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This mink is in the diagonal walk gait. The normal gait pattern for mink is the bound, as introduced in an earlier post. When an animal is out of its usual gait, something interesting may be happening. Not only has this mink shifted down to the slower gait, there are drag marks. I followed the tracks, and they led me to a hole in the snow.

 

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Noting the blood drops, I excavated the hole a little, and there was a leopard frog.

 

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The frog was still wet and soft. It was so freshly killed that I thought it likely the mink had heard me coming and quickly stashed its prey. I backtracked, found where the mink had dug the hibernating frog out of the mud at the edge of the creek, and went on my way so the predator could retrieve its meal.

Words of Tracking: Common Walking Gaits

by Carl Strang

 

In an earlier set of posts (find under Methods category in sidebar to left) I introduced the alphabet of tracking, i.e., identification of the kind of animal that made the track. Today I want to take the next step toward reading the stories that footprints have to tell us. That is, to look at the basic gaits. A gait is a pattern of footprint placement, the building block from which an animal’s trail is built, and it also is the order in which the feet step as the animal moves. You will find the same gaits given different names in different references. I follow the terminology of my teachers at the Tom Brown school (link in left margin of the frame).

 

The pace gait is the usual traveling gait of certain animals, such as raccoons and bears, whose wide-bodied proportions favor swinging their weight from side to side, stepping with both left feet at once, then both right feet. If you try this, in a comfortable rather than lunging effort, you will find that your feet produce side by side pairs of footprints, left front foot beside right hind foot, right front foot beside left hind foot. Here is the pattern in a set of raccoon tracks.

 

Pace gait, raccoon

Pace gait, raccoon

 

 

The opposite of a wide body is a long skinny body, which we find in weasels. If your body is, to exaggerate, something like a rope with two little feet at each end, the easiest way for you to proceed will be to move both your front feet together, then both your hind feet, with the hind feet landing behind the front feet. This gait is called the bound. Often the feet are somewhat offset, an indication that the animal oriented its body axis at an angle rather than in line with its direction of travel.

 

Bound gait, mink

Bound gait, mink

 

 

Another gait in which the front feet move together and the hind feet move together is the gallop. This is common in rodents and rabbits, animals whose hind legs are more powerful than the front, so that the hind feet land in front of the front feet. Cottontails typically place one front foot in front of the other, while rodents such as mice and squirrels, as well as masked shrews, place their front feet side by side (in the photo the shrew is moving left to right).

 

Gallop gait, cottontail

Gallop gait, cottontail

 

Gallop gait, masked shrew

Gallop gait, masked shrew

 

 

There is one circumstance in which cottontails place their front feet side by side, however. I will leave this one for you to puzzle over. Look for examples this winter, see if you can figure it out. Here’s a photo so you know what to look for.

 

Cottontail gait puzzle

Cottontail gait puzzle

 

 

The final common walking gait is typical of hoofed animals (white-tailed deer in NE Illinois), the dog family and the cat family, as well as us (when do we walk on all fours?). This one is called the diagonal walk, and unlike the others the feet move separately in a sequence: left front, right hind, right front, left hind. In this case the left feet come down in close to the same place, and so do the right feet. The overall impression is a zigzag between right foot pairs and left foot pairs, hence the name for this gait.

 

Diagonal walk gait, wolf (Isle Royale)

Diagonal walk gait, wolf (Isle Royale)

 

 

There are other gaits, but they are less common or are special cases and will be reserved for later. Also, the connections I have made between animals and gaits are limited to routine travel. When circumstances require, animals shift out of their normal walking gait. For instance, a raccoon in an extreme hurry does not, cartoon like, do a real fast pace gait. Instead, it shifts into a gallop. Tracks outside the normal pattern are a clue that something unusual, therefore interesting, was happening.

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