Differentiating Mountain Lion and Dog Tracks

1. What they did

Hunters, managers and researchers use mountain lion tracks to learn where lions live and roughly how many there are. Yet many people, trained wildlife biologists included, find it hard to tell lion tracks from dog tracks. In a statewide track survey in California, at least 9.5% of the volunteers could not tell them apart, even though most volunteer teams included a wildlife biologist.

The authors worked in three parts:

• Testing the published differences. They listed ten differences between lion and dog tracks given in the literature and checked each one against the tracks they had collected in California over five years of field work. They also noted extra traits that helped.
• Measuring tracks. They traced the tracks of 19 dogs and 48 mountain lions onto acetate sheets and measured several traits. A multiple group discriminant analysis, a statistical method that uses known cases to sort unknown ones into groups, showed which traits best separated the two species, for all tracks, front tracks only and rear tracks only.
• Building a key. They combined the best traits into a simple field key.

The work covers tracks in dust or firm mud only. The authors had little experience in snow and found that soft mud distorts tracks badly.

2. What they found

The published differences

• Claw marks: the authors never saw a lion track with claw marks, though professional trackers and other authors report them, and say they are much thinner than a dog’s. Two of the 19 dogs left tracks without claw marks. An excellent clue, but not a perfect one.
• Heel lobes: most dog tracks showed two lobes at the rear of the heel pad, but a fair number showed three. In dog tracks with three lobes, the outer two were smaller than the middle one, while a lion’s three lobes were more equal in size and shape.
• Overall shape: not all dog tracks were long and not all lion tracks were round. In both species the rear tracks were usually longer than the front ones. A poor clue.
• Leading toe: lion tracks usually had a leading toe, but some were nearly symmetrical, and a few dog tracks had a leading toe too. Not to be used alone.
• Front of the heel pad: no dog track had the squared front edge of a lion’s heel pad, but some lion rear tracks failed to show it and looked pointed like a dog’s.
• Toe shape: lion toes were usually more pointed, but dog toes varied too much to rely on this alone.
• Track pattern: lion tracks more often came in pairs from the same side of the body, the rear foot on top of or just in front of the front foot. Dog tracks were more often single and evenly spaced, and dog pairs were usually side by side. Lions sometimes left single, evenly spaced tracks too.
• Heel pad size and shape: heel pad size relative to the whole track was often similar, but dogs had a much greater variety of heel pad shapes.
• Belden’s toe to heel ratio: did not work often enough to rely on alone.

New clues

• A mound of soil between the toes and the heel pad: almost always present in dog tracks, never seen in a lion track.
• Travel on roads: dogs often wandered erratically, at varied speeds, stopping and starting. Lions either took the shortest route, cutting corners, or kept to one side of the road. About half of lion track sets stayed to one side; with cover on both sides, the lion kept to the uphill side, but moved to the downhill side where only that side had cover.

The measurements

• The angle between the long axes of the two outer toes separated the species best, and worked equally well for front and rear tracks: it correctly classified all 161 lion tracks and 94% of the 63 dog tracks (98.3% overall).
• The ratio of the widths of the second toe and the heel pad was also good, more so for front tracks. The distance between the middle toes was fair, again better for front tracks. The distance from the middle toes to the heel pad worked fairly well for rear tracks but not for front ones.
• Adding more traits never improved results enough to justify using them in the field. The toe to heel ratio actually lowered the accuracy of the toe angle when the two were combined.

The key

Before using the key, screen out other species and obvious dog tracks (the smallest adult lion track had a heel pad 37 millimetres (mm) wide, and lions always have three lobes at the rear of the heel pad).

• Heel pad concave at the rear, two lobes: dog. Three lobes: go to 2.
• Front of heel pad squared or concave: mountain lion. Rounded: go to 3.
• Claw marks present: go to 4. Absent: go to 5.
• Claws blunt: dog. Claws knife-like, very narrow: mountain lion.
• Angle between the outer toes 20 degrees or less (all lions and 6% of dogs): go to 6. 21 degrees or more: 94% of dogs.
• Check all the other clues together to bring accuracy to 99%.

3. What they concluded

• Almost every published difference between lion and dog tracks works some or most of the time, but each has enough exceptions that none should be used alone.
• The angle between the outer toes is a new and highly effective clue, and the ratio of the widths of the second toe and the heel pad, adapted from Belden (1978), is also useful. Their effectiveness may drop as more dog tracks are measured, but the early results are encouraging.
• Field biologists can greatly improve their identifications by using the key together with the toe to heel ratio, the leading toe, toe shape, the mound of soil, the track pattern and travel behaviour.
• The knife-like claw marks in step 4 were not seen by the authors; they reason that lion claw marks, if they appear, should be very thin because the claws are narrow and sharp.
• Lions in other states may leave different tracks, but the same method can be applied elsewhere. Discriminant analysis may reveal further useful traits.

4. How tracking was or was not used

Tracking is the subject of the paper. The authors identified lion and dog tracks and track patterns on roads in dust and firm mud, measured tracks traced onto acetate, and read travel behaviour from track sets. The paper does not say how the identity of each measured track (lion or dog, and which individual) was known.

5. Tracker or observer certification

Reported but not validated. The authors base Part 1 on five years of their own field work and on reports from professional trackers, but no certification or test of their skill is described. Rob Gross and Joan Young are thanked for collecting dog tracks. The paper also reports that at least 9.5% of volunteers in a California track survey could not tell lion and dog tracks apart.

6. Other technologies, skills or innovations

• Tracing tracks onto acetate sheets (after Panwar 1979) for measurement.
• Multiple group discriminant analysis to find the most useful track traits.
• A dichotomous field key for lion and dog tracks.

7. Implications for conservation (from the paper)

• Tracking can be an important and inexpensive tool for studying mountain lions, but it must be used accurately. Because people often confuse lion and dog tracks, the use of tracks in lion research and management is often questioned.
• Errors in published track illustrations and descriptions may add to misidentifications.