By Matthew Scrafford

Photo credit: Liam Cowan.

Tracks left by wildlife provide a wealth of information that can help to inform wildlife management and conservation efforts. Biologists like me use them to understand what species are present in an area, their abundance, their habitat use and movement and what they eat. Many biologists prefer to use tracks to research wildlife because it is less invasive and costly than live trap and release programs or luring wildlife into the range of cameras. In this blog we discuss some of the ways that WCS Canada biologists use tracks to study wolverines.

One way we are using tracks is to help colleagues in Washington State understand what is happening with wolverines there. WCS Canada is partnering with the Cascades Wolverine Project (CWP), a non-profit environmental organization based out of Washington that focuses on wolverine research, monitoring, and education in the North Cascades mountain range. Following human settlement of North America up until relatively recently, wolverines were rare in the mountainous areas of the western United States, especially in the North Cascade Mountains of Washington State. Excitingly, wolverines have recently dispersed from existing populations in the Rocky Mountains to the north to recolonize some of their former habitat here. CWP is playing a vital role in monitoring this vulnerable population at its southern range edge.

CWP has a track observation program that encourages the public to submit photos and locations of wolverine tracks they find while out enjoying the countryside in the North Cascades (for tips on identifying wolverine tracks see the side bar). These data will allow CWP to understand the current distribution of wolverines and monitor any potential changes in this distribution. However, distinguishing tracks in the field can be challenging for those even with extensive field experience. Soft and deep snow might not register a clear paw pattern or the animal may not create a distinguishable trail pattern. Or maybe the track has melted in the sun or been blown-in by the wind and is hard to recognize. This creates uncertainty in whether tracks observed by people in the field are actually from the species they believe it is.

Therefore, CWP has trained biologists and professional trackers to vet public track submissions to ensure they are from wolverines. Biologists and professional trackers are skilled at identifying tracks in the field where they can use numerous lines of evidence to make an educated guess on what made the track. Interpreting track submissions on a computer screen presents additional challenges including lighting and scale. Therefore, we need to be able to test the ability of those charged with ensuring the accuracy of identifications to connect track photos to the animal that made them. But how can you ever be sure that a photographed track is from a particular species?

Our wolverine project in northwestern Ontario helps with this. We have a system of 29 live traps spread over a 6,500 km² area near Red Lake. The main objective in having these live traps is to allow us to attach GPS collars to wolverines so we can understand wolverine movement, habitat selection, reproduction, abundance, and foraging in a lowland boreal ecosystem with abundant forestry. (See our Story Map to learn more about our wolverine research in Red Lake.) But these live traps capture more than just wolverines, including fishers, lynx, and wolves. Our ability to know just what species is inside the trap (after taking a careful peak) offers us a unique opportunity. When we release the animal we can follow its path and photograph and measure its tracks, using the methods that CWP encourages for track submissions.  And we will know with little doubt that we are collecting tracks from a particular species. We don’t need to say “those tracks sure look like wolverine” because they are wolverine! We don’t need to say “I bet these are lynx tracks” because we know they are lynx tracks! Even the best trackers in the world can’t identify a track with such certainty.

We can then use these verified photos to test the biologists and professional trackers on their ability to identify tracks from photos. If they ace the test, CWP knows that its current standards for submitting photos are sufficient and can be confident in its data set. If they fail, we may need to modify what we are asking for from community scientists.  For example, they might need to submit additional information about the area or the photo might need to be taken at a different angle or with better lighting. There also might need to be a recognizable object in the frame to see the scale of the paw prints. Confirming a wolverine track can hinge on such details.

Besides a measure of track-identification error, these tests also will provide information on what characteristics of tracks are most difficult to distinguish between species, the species most often confused with wolverines, and the snow conditions that might lead most often to track error. These data will feed into the development of methods and trainings for citizen scientists and biologists to ensure they more accurately identify wolverine tracks in the snow, ultimately making tracking data more reliable for wolverine monitoring, research, and conservation. 

But the importance of tracks to the WCS Canada wolverine program doesn’t stop here. For example, over 10 years, WCS Canada biologists flew aerial surveys to identify the location of wolverine tracks in the snow throughout northern Ontario. Wolverines are a threatened species in Ontario that reside in northern areas of the province that are hard to access. The tracks documented in our aerial surveys were used to understand current wolverine distribution, their potential range expansion since European settlement, and variables that might affect their distribution (Fig 1; Fig. 1.1) .

Figure 1. WCS Canada biologists have flown aerial surveys for wolverine tracks in the snow throughout northern Ontario. The hotter colours in this map are areas where wolverine tracks are more likely to be seen.

Figure 1.1. Wolverine tracks in a 3 x 3 trail pattern as observed during an aerial survey (Photo credit: Justina Ray).

We also use tracks to piece together the behaviour of wolverines at their feeding sites. This past winter in Red Lake, Ontario wolverine M16 had spent three weeks at a pond and wetland area. We walked into the site after he had left for other parts of his range. As we approached, we first noticed beaver tracks and trails in the snow leading to stands of alder and willow that the beavers were foraging. This suggested that the beavers had exhausted their underwater cache that winter and were looking for their food on land – something we often observe in late winter and early spring. But beavers are susceptible to predation when on land, especially in the winter when there is no open water to waddle back to when predators appear. Wolverine M16’s tracks, as well as beaver remains in the area, showed us that he had ambushed and killed at least one beaver while it was on land. We then traced M16’s tracks back to a beaver lodge that he had excavated in an attempt to kill more beavers (Fig.2). His tracks then went to upland forested areas surrounding the beaver pond where he fed, digested, and rested (Fig.3). He even had tracks that led us to latrines where stacks of scat were piled (Fig.4). The long duration of his stay at the beaver pond and the volume of scat suggested that M16 had killed multiple beavers in the area.

Figure 2. A WCS Canada biologist inspects a beaver lodge that was excavated by wolverine M16 (Photo credit: Matt Scrafford). 

Figure 3. Wolverine M16’s resting area in the uplands surrounding a beaver pond. Note the melted out snow where he was resting. M16’s tracks led us from the site he killed the beaver directly to his resting area (Photo credit: Matt Scrafford).

Figure 4. M16’s scat pile or latrine near his resting area. We collect these scat to understand the prey the wolverine is feeding on (Photo credit: Matt Scrafford).

We hope our work with tracks will further wolverine conservation outcomes and research throughout North America. As long as tracks are identified correctly, they are a powerful tool in wildlife research. Give tracking a try! You might find that you enjoy deciphering tracks as much as we do.     

Identifying wolverine tracks

Wolverine tracks can be tricky to identify in the field because wolverines share habitat with species whose tracks are similar (e.g., lynx, wolf). But there are a few important characteristics that can be used to distinguish their tracks. Wolverine tracks are often in a 3 x 3 trail pattern, or lope, when they are running on a firm surface including hard-packed snow or roads (Fig.5).

          Figure 5. Wolverine tracks are often in a 3 x 3 trail pattern when they are running, or loping, on a firm surface including roads or frozen streams and lakes. This pattern is excellent evidence that the tracks you are following belong to a wolverine (Photo credit: Matt Scrafford).  

This pattern is very obvious when looking down at tracks during aerial surveys and is one of the easiest ways to distinguish a wolverine track from other similar sized wildlife. A wolverine trail pattern also can form in a 2 x 2 pattern if they are not moving quite as fast, or potentially bounding, in deeper snow (Fig. 6; Fig. 7). Both a 2 x 2 and a 3 x 3 trail patterns can show a wolverine dragging its paws or bits of fur as it moves.

Figure 6. A wolverine will sometimes run in a 2 x 2 pattern when not in such a rush or when in deep snow. Note the drag marks between tracks which is toe fur scrapping on the surface of the snow (Photo credit: Matt Scrafford).

Figure 7. A wolverine’s bounding trail pattern across a beaver pond (Photo credit: Matt Scrafford).

If the snow conditions are right, the details of the wolverine track will register or leave an imprint in the snow. One of the primary clues that a track is from a wolverine is that there are five toes visible that are evenly spaced. Moreover, there should be some claw marks (wolverines have semi-retractable claws), the pad or metacarpal should have a relatively flat leading edge, and the overall heel pattern should look like an ice cream cone (Fig. 8-10).

Figure 8. Wolverine tracks across a beaver meadow. Note the alternating 2 x 2 and 3 x 3 trail pattern, the toe drag, the 5 toes, and the ice-cream cone shape of the tracks. The wolverine’s snowshoe like paws allow it to float over the snow, sometimes (Photo credit: Matt Scrafford).  

Figure 9. If the snow conditions are right, the details of the wolverine track will register or leave an imprint in the snow. One of the primary clues that a track is from a wolverine is that there are five toes visible that are evenly spaced. Moreover, there should be some claw marks (wolverines have semi-retractable claws), the metacarpal pad should have a relatively flat leading edge, and the overall heel pattern should look like an ice cream cone (Photo credit: Matt Scrafford).  

Figure 10. The furry paw of a wolverine (Photo credit: Matt Scrafford).

The wildlife tracks easiest to mistake for a wolverine are lynx and wolf. However, both species typically register four toes and have a more rounded or ovular heel pattern. Lynx rarely register claws, have a rounded pad, and generally do not drag their paws or toe fur while walking (Fig. 11). Wolves will register claws, have a pointed pad, drag their paws while walking, and have large spacing between tracks (Fig. 12). Both species most often walk in a 2 x 2 (Fig. 13) or 1 x 1 pattern (Fig. 14) but rarely a 3 x 3.

Figure 11. Lynx rarely register claws, have a rounded metacarpal pad, and generally do not drag their paws or toe fur while walking. Can you imagine your house car dragging their paws while walking? (Photo credit: Liam Cowan).

Figure 12. Wolves will register claws, display a pointed metacarpal pad, drag their paws while walking, and have large spacing between tracks (Photo credit: Matt Scrafford).

Figure 13. Wolf tracks a long a forestry road. Note the 2 x 2 pattern and the large spacing between tracks (Photo credit: Matt Scrafford).

Figure 14. Semi-melted lynx tracks showing a typical lynx trail pattern when walking (Photo credit: Matt Scrafford).