Animal Tracks - Opossum (Didelphis virginiana)


Natural History of Opossums
	Opossums are the only North American marsupials. A marsupial is an animal with a pouch, like a kangaroo.
	Opossums have pointed noses and naked tails. They are the only North American mammals with prehensile (grasping) tails. The tail is used to assist in climbing. It also stores extra fat reserves, enabling the animal to survive lean times. Opossums have opposable thumbs on their hind feet which help them to grip branches and climb. They are the only non-primates with opposable thumbs. Opossums have the most teeth of any North American mammal. In the trail pattern at left, the two tracks, front and hind, overlap each other. Because the tracks are doubled, the trail can look like that of a much larger animal. Early morning is the best time to find their tracks. The trails in fine, dry soil tend to age quickly, especially along riparian areas. Opossums can be found in many environments, including cities and wilderness. They are opportunistic feeders and can utilize many of the scraps people throw away, thus they are often found raiding pet food dishes and garbage cans.

When baby opossums are born, each one weighs 1/200 of an ounce, is less than ½ inch long, and lacks fully developed hind limbs. Up to 14 young are born after only 12 to 13 days of gestation. Of these 14 young, only about nine survive. The entire litter could fit into a teaspoon. They climb into the mother's pouch, where they remain for about ten weeks. When they are big enough, they ride around on their mother's back.

Baby opossum.

Opossum trail in sand near the Eel River.
December 2000.

When attacked, an opossum can play dead, or "play possum." When using this defensive strategy, they drool and emit an unpleasant smell which discourages predators. They also climb to escape danger. When threatened, they will hiss and show their 50 sharp teeth.

They nest in abandoned burrows or fallen trees. Opossums eat a variety of foods and are able to adapt to many different environments, from cities to wilderness.

Their tracks show five toes on the front foot and five toes on the rear, including the opposable thumb. The thumb lacks a claw.

On the left is the trail pattern of an opossum in river sand. The tracks nearly overlap each other in the alternating pattern that is typical of a walking opossum. The opposable thumb is very prominent in some of these tracks.


This beautiful left front opossum track shows all the details very well. The tiny inner toe, or thumb, is easy to make out on the left side. The five toes, splayed due to the mud substrate are visible. Claws even left imprints on a couple toes. Compare this track with those on the raccoon page. The front track of the opossum can be confused with the raccoon's tracks easily.


This clear right hind opossum track shows the opposable thumb very well. This characteristic sets opossums apart from other north American mammals. Opossums are the only one of our wild mammal species that has an opposable thumb. There are Australian species that have this feature, but the opossum is the lone representative in North America.


Beautiful right front track covered by right hind track. The hind track is a nearly perfect specimen of an opossum track. You can clearly see that the thumb lacks a claw. The other toes all have claws. The middle three toes are aligned next to each other and face the same direction. This is a real beauty! Yes, trackers get very excited about things like this. :)


This pair of opossum tracks shows a perfect left front and a perfect left hind. This fine mud held nice imprints and showed a lot of detail. These are classic opossum tracks!


Here is another nice example of the left hind footprint of an opossum. The thumb clearly shows here, as do the other four toes.


This was an exceptionally good pair of opossum tracks found in soft dusty soil. The fine soil captured the details of the feet quite well. These are the left front and left hind tracks of the opossum.


Another beautiful pair of opossum tracks in mud. In this case, a worm has made its way across that left front track, underground. There is also evidence of worm castings near the outer toe on the left hind track. These are fine opossum tracks!


The tracks above came from the same opossum that left the tracks in the photo above this one. This shows a nice example of how tracks can look different depending on the soil or the substrate. in this case, the sane was more firm than the fine mud was. The opossum did not sink as deeply into the sand and did not leave imprints that are as deep or clear as those above in mud. This is true for all animals and humans. The substrate you walk on makes a big difference in the appearance of the tracks you leave behind.



Two left hind opossum tracks. These footprints show the opposable thumb that makes this animal unique in North America.

	A pair of left tracks. The hind track overlaps that of the front foot.

	A nice opossum walking gait pattern in mud near a river. The hind tracks land on top of the front tracks. The direction of travel is from the bottom toward the top of the photo.

A set of opossum tracks, showing the left hind track on top of the left front track. The opposable thumb is very easy to see in these prints.

	A perfect set of left footprints from an opossum. These were photographed in light conditions such that, at times, the tracks can appear to pop off the page. This is an optical illusion that sometimes happens with track photos.


A beautiful left hind track from an opossum. Notice the thumb lacks a claw.


A section of river bar with tracks of several species, including raccoon, gray fox, and opossum.


The left front and hind tracks of an opossum on top of the tracks of a gray squirrel. The opossum's direction of travel was toward the top of the photo. The squirrel was going in the opposite direction.


The left hind pawprint of an opossum. Note the nice imprint of the opposable thumb.


The front and hind tracks of an opossum. These are the left tracks.


A nice set of right tracks from an opossum. These show a bit more wear and tear than the ones above. This is just a function of the mud that was walked in.


A good set of opossum tracks. These are the prints of the left hind and left front paws. Notice the large opposable thumb on the hind track, which is the lower one.


A nice front opossum track in snow. Photo donated. (Thank you!)


A pair of opossum tracks in snow. These are the right front (top) and right hind (bottom) pawprints. Photo donated. (Thank you!)


Personal Notes on Opossums
I recently walked outside at night and happened to see a very small animal by the woodpile. Upon closer examination, I determined that it was a baby opossum. I watched on the following nights and was treated to the sight of three baby opossums making their first forays out into the world. Their little ears were pink and looked too large for their heads. They moved slowly and tried out their climbing skills in a nearby tree. Fascinating animals to watch. When I used to live in the city, opossums would come around at night and get into the garbage cans. They used overhead powerlines as a sort of aerial highway. Pretty smart.

The left pair of tracks. Front track is ahead of the hind track. Note the opposable thumb in the hind track.	The right pair of opossum tracks. Quarter gives scale.

	This plaster cast of the hind foot of an opossum shows details that normally don't show up in field casts. The structure of the opposable thumb is easy to see here.
This young opossum visited me one night when I left some snacks outside. Here he is devouring some tasty morsel.
	Another young visitor. These young opossums were probably 8 or 10 weeks old. Photos taken in summer 2000.
Still another of my opossum visitors. Photo taken near Redway, California.
	This opossum got into the kitchen and was hiding behind the stove. It left on its own when I left the door open for it.



This opossum visited my trail camera. It looks like it is smiling for the camera.


Another opossum who visited the trail camera.

Opossum Tracks
Didelphis virginiana

Hind Track	Front Track
1 7/16-2 3/8 in. L X 1.25-2.25 in W	1-1 11/16 in. L X 1-2 7/16 in. W
Opossum Tracks


Opossum tracks in sand. Front foot at top and right hind foot on the bottom. The hind print partially covers the front one.	Opossum trail pattern diagram.