May 2024 Natural Mystery Answered

We didn’t receive any correct answers to our May Natural Mystery—so we’ll dive in and explore it together. Thanks to everyone who submitted a guess. I’ll do my best to cover the features that set these tracks apart, and how we can determine which side of the body they came from.

These are the left side tracks of a muskrat (Ondatra zibethicus).

Two tracks are visible in this image. Let’s begin with the track on the left. This track shows four long, slender toes, splayed out across about 90° of arc; a relatively small palm; and two round heel pads. A small fifth toe is visible near the base of the palm. There are faint claw marks visible beyond the tips of some of the toes. The track measures 1⅛″ (2.9 cm) long and 1″ (2.5 cm) wide. These features are consistent with the front track of a medium-sized rodent. Rodents in our area with front tracks about this size include muskrats and several of our squirrels. Brown rat tracks would be smaller, with a more compact palm and heel area, and wider splaying toes.

The track on the right shows five long toes and a broad, poorly defined palm. No heel is visible. Stout claw marks are visible beyond the tips of most of the toes. The toes are much wider than those on the smaller track to the left. Some of the toes also appear to show a narrower shaft in the center of the toe compression, surrounded by a small “shelf” in the mud. The three center toes register more prominently than the two outer toes. These features are typical of a muskrat hind track. No other rodent has a similar looking hind track.

One key to quick identification of muskrat tracks like these is the contrast between the front and hind tracks. Seen by itself, the front track resembles that of a squirrel. In isolation, the hind track might be mistaken for the front track of a raccoon or an opossum. The combination of these two tracks, and the considerable size difference, are distinctive. Since muskrats walk with an indirect registration pattern, we usually have both front and hind tracks visible in a trail. But for those occasions when we do not, here are a few other features that can help us distinguish the individual prints from those of other species.

Squirrel front tracks are less likely than those of muskrat to show the full length of each toe. Muskrats have stouter claws than tree squirrels, and a more symmetrical arrangement of their toes than ground squirrels. Toe 1 (the thumb) registers more often and more prominently in muskrat tracks than in squirrel tracks.

The toe impressions in raccoon and opossum front tracks lack the “shelf” often visible in muskrat hind tracks. Both species are more likely than muskrats to show a clear palm pad, and raccoons sometimes register a heel pad as well.

Thanks again to everyone who submitted an answer to this mystery!

Support the Newsletter

If you enjoy these natural mysteries, please consider supporting the Minnesota Wildlife Tracking Project newsletter on Patreon or buy me a coffee.