Date: Feb 29, 2024

Place: South end of Guelph ON.

Time: 9:15am (ish).

Main references:

‘Mammal Tracks & Sign: A Guide to North American Species’, Mark Elbroch and Eleanor Marks, First Edit., Stackpole Books

Discussion: the temperatures plummeted yesterday and last night and we got a light dusting of snow, perfect on our driveway for showing the finer details of tracks! I have often seen in the past what I thought were mouse tracks on the edge of the driveway near the garage door. The trail width (and other measurements) show that this is not a mouse, but a chipmunk doing a classic bound gait! I have actually seen chipmunks recently as it got warmer.

I wanted to get away from measuring things to the nearest 1/16 of an inch, but in this case measurements were clearly needed (I’m sure in the future I won’t need to measure – I’ll just know by sight the difference in size between mouse and chipmunk trail widths). Here are my measurements:

stride (inches): 26 1/4, 22 1/4, 22, 18, and smaller

trail width (inches): 2 1/4, 2 1/4, 2 1/8 (last picture)

group length (inches): 3, 3, 2 1/4 (last picture)

front width x length (inches): 1/2 x 1

hind width x length (inches): 9/16 x 1

And here are the measurements given in Elbroch (pp. 257-258):

bound stride (inches): 4 – 23

trail width (inches): 1 3/4 – 2 7/8

group length (inches): 2 – 5

front width x length (inches): 7/16 – 7/8 x 3/4 – 1

hind width x length (inches): 5/8 – 15/16 x 1/2 – 7/8

So my measurements are mostly consistent with these. I did have one stride length that was slightly outside this range, and I probably over-estimated the length of the hind feet.

Some observations & comments:
As the bounds continued the stride lengths decreased until we had the tracks in the last photo shown above. I had learned in the tracking course that as speed increases the trail widths usually decrease. In the final photo the trail width seems slightly smaller, the group length is less, and the toes seem more splayed (coming briefly to a stop?).

I just went out (2 hours later) to check on the shorter stride lengths, but the wind and other disturbances have made measurements difficult. I did notice a fresh set of chipmunk tracks going in the opposite direction!