# The challenge of monitoring elusive large carnivores: An accurate and cost-effective tool to identify and sex pumas (Puma concolor) from footprints

> Pumas have no spots or stripes, so how do you tell one from another? Using photographs of left hind footprints from 35 captive pumas, researchers correctly told individuals apart in more than 90% of tests and sexed a single footprint correctly 99% of the time. The method offers a cheap, non-invasive way to count these elusive cats, as long as someone can find and read a clear footprint.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2017-alibhai-jewell-challenge-monitoring-elusive-large/

## Citation and access

- **Authors:** Sky Alibhai, Zoe Jewell and Jonah Evans
- **Year published:** 2017
- **Journal or source:** PLOS ONE
- **Full citation:** Alibhai, S., Jewell, Z. and Evans, J. 2017. The challenge of monitoring elusive large carnivores: An accurate and cost-effective tool to identify and sex pumas (Puma concolor) from footprints. PLOS ONE 12(3): e0172065.
- **DOI:** 10.1371/journal.pone.0172065
- **Access status:** Open access (CC0 public domain dedication)
- **PDF:** https://www.originalwisdom.com/wp-content/uploads/2026/11/2017_Alibhai_and_Jewell_etal_the-challenge-of-monitoring-elusive-large-carnivores.pdf

## Tags

- **Species:** Mammals > Mountain lion
- **Region:** North America > United States
- **Tracking:** Individual identification; Track measurements; Track photographs; Tracking; Tracks; Tracks and signs identification; Trailing
- **Methods and technology:** Footprint Identification Technology (FIT)
- **Data type:** New field data
- **Observer qualification:** Not reported
- **Discipline:** Wildlife tracking
- **Year published:** 2017

## Detailed keywords

- **Species:** Studied: puma (Puma concolor), also called mountain lion, cougar, panther and catamount; 35 captive pumas (19 females, 16 males, aged 1 to 20 years) and two free-ranging pumas. Mentioned from earlier footprint identification work: fisher (Martes pennanti), tiger (Panthera tigris), black rhino (Diceros bicornis), white rhino (Ceratotherium simum), snow leopard (Panthera uncia), jaguar (Panthera onca), brown bear (Ursus arctos), European pine marten (Martes martes) and cheetah (Acinonyx jubatus); snow-footprint work on Amur tiger, giant panda and polar bear.
- **Location and habitat:** United States. Captive pumas at 10 facilities: Capital of Texas Zoo, Center for Animal Research and Education (CARE), Fort Worth Zoo, Houston Zoo, In-Sync Exotics, Maine Wildlife Park, Northwest Trek, Pride Rock Wildlife Refuge, Wild Animal Orphanage, and Wildlife Rescue and Rehabilitation; footprints laid in prepared builder’s sand paths. Free-ranging pumas: Big Bend National Park, Texas, and Camino Cielo, Los Padres National Forest, California.
- **Topics:** Footprint Identification Technique (FIT); identifying individuals from footprints; sexing from footprints; left hind footprints; standardized footprint photography protocol; footprint quality; non-invasive monitoring; welfare costs of capture and collaring; population estimation (absolute counts, minimum known alive, capture-recapture with footprints as the “mark”); combining footprints with camera traps; “footprint traps”; citizen science.
- **Statistics or models:** FIT software as an add-in to JMP (SAS); 25 landmark points and 15 derived points per footprint; stepwise variable selection by F-ratios; robust cross-validated pairwise discriminant analysis (Fisher’s canonical variates, centroid plots with 95% confidence ellipses, a reference centroid value); Ward’s clustering and dendrogram; holdback (training and test set) validation with 10 random iterations per test size; linear discriminant analysis for sex, validated by jackknife and data partitioning; relative likelihood slider for the number of individuals. Inconsistencies in the paper: the abstract and section 1.8.2 give 123 measurements per footprint, but sections 2.5.1 and 2.5.2 give 128. Table 2 lists 79 trails, but the dendrogram classifies 77. The methods say the sex model used the 10 best variables, but Table 1 and Fig 10 give 20 (and the results call 20 the optimum “for individual classification” in the sex section). The abstract gives sex accuracy as over 99%, the results as 99%. The text says ages ranged 1 to 20 years for both sexes, but Table 2 gives a female range of 1 to 14.3 years; no test is shown for the claim of no significant age difference (means 9.13 and 12.63 years). The results give 93.2% accuracy with 28 test and 7 training animals, while the Fig 5 caption mentions a 24:11 split.
- **Data type:** New field data: footprint photographs from captive pumas and from free-ranging pumas in Texas and California (no collection dates given). The full measurement dataset is published with the paper (S1 Table).

## Synopsis

### 1. What they did

Pumas are solitary, elusive and mostly active at night, so they are hard to count. Capturing and collaring them is expensive and can harm the animals, and pumas have no spots or stripes for camera traps to tell individuals apart. The authors set out to show that the Footprint Identification Technique (FIT), first developed for black rhino, can tell individual pumas apart, and tell males from females, from photographs of their footprints.

- Collecting footprints. At 10 captive facilities across the United States, they raked builder’s sand into paths about 1 cm deep and 2 to 3 m wide and had pumas walk over them at a relaxed pace. They photographed left hind footprints only, from directly overhead, with a ruler and a photo slip in each picture. Only clear footprints were used.

- The reference set. 535 footprints from 35 pumas: 19 females (300 footprints) and 16 males (235 footprints), aged 1 to 20 years, in 2 to 3 trails per animal on average.

- Measuring. In the FIT software (an add-in to JMP statistics software), 25 landmark points were placed by hand on each footprint image and 15 more were derived from them, giving well over a hundred distances, angles and areas per footprint.

- Identifying individuals. Trails were compared two at a time. If the confidence ellipses around two trails overlapped, they were judged to be the same animal. A clustering step then grouped trails into individuals. Accuracy was tested by holding back some animals as “unknowns” and classifying them against the rest.

- Sexing. A separate discriminant analysis was built to classify single footprints as male or female.

- Free-ranging test. Footprints from two wild pumas, one in Big Bend National Park, Texas, and one in Los Padres National Forest, California, were run through both models.

### 2. What they found

Telling individuals apart

- When test sets were small relative to the training set (4 test animals against 31), accuracy was highest. Even with 28 test animals against only 7 in the training set, accuracy was 93.2%.

- In the clustering, 3 of 77 trails were placed with the wrong animal, giving 96.11% correct trail placement.

- The software’s likelihood slider gave 73.7% likelihood for 34 pumas and 76.9% for 36, when the true number was 35.

- The two wild pumas were correctly separated as two individuals, distinct from each other and from all captive animals.

Telling males from females

- About 20 measurements gave the best result. Sex was classified correctly 99% of the time from a single footprint.

- The wild puma from Los Padres National Forest was classified as male, and the one from Big Bend as female. The paper does not say whether these were confirmed.

What makes a good footprint

The clarity of the heel pad and toe outlines decides quality. Hind feet often land on the front footprints, hind footprints are longer, narrower and more symmetrical than fronts, the third toe is the longest, and the first toe does not show.

### 3. What they concluded

- FIT is an accurate, non-invasive and inexpensive way to identify and sex individual pumas from footprints, and could be used for other large cats.

- Footprints could be collected systematically in a small closed population for an absolute count, opportunistically over a larger area for a minimum known alive estimate, or used as the “mark” in capture-recapture estimates.

- FIT could be combined with camera traps, for example by preparing the ground in front of a camera so whole-animal images can be matched to footprints.

- Limitations: the method needs good impressions in a suitable substrate, and the person collecting must be able to recognise a puma left hind footprint. Where substrate is poor, sand “footprint traps” in travel corridors may help.

- Next steps: wider field validation with free-ranging pumas on different substrates, and on snow.

### 4. How tracking was or was not used

The whole method rests on tracks and signs identification. The authors say the photographer (or an assistant, who might be an expert tracker) must be able to recognise a puma left hind footprint on the ground and follow the trail of footprints forwards or backwards along the line of travel. They describe how to tell hind from front footprints and left from right. Footprints from free-ranging pumas were also collected, one trail per area, so each trail came from a different animal. The authors note that even experienced biologists can struggle to identify footprints, but in their experience most observers could identify puma left hind footprints after a day of training. Because the footprints are photographed, a skilled observer can check them later.

### 5. Tracker or observer certification

Not reported. The paper does not say who collected or identified the footprints, or test their skill. Several people are thanked for contributing puma footprint images.

### 6. Other technologies, skills or innovations

- FIT software as an add-in to JMP data visualization software, with a single graphical interface and built-in validation.

- A standard photography protocol: camera directly overhead, ruler along two edges, photo slip in the frame, footprint shaded to avoid partial shadows.

- Prepared sand paths for collecting reference footprints from captive animals.

- The authors’ earlier video guide to FIT using cheetahs is included as supporting material.

### 7. Implications for conservation (from the paper)

- Capture with dogs or snares can injure or kill pumas, and repeated capture, immobilization and collaring can harm health, behaviour and breeding. A non-invasive method avoids these costs and the risk that invasive methods bias the data.

- Footprints are the most common animal sign, and collecting them is simple and cheap, so expert trackers, conservation biologists and citizen scientists could all contribute.

### 8. Implications for tracking (Original Wisdom's observations)

_These are Original Wisdom's observations, not the authors'._

- The method depends on basic tracking skills: recognising a clear left hind puma footprint and following the trail. The study does not test how accurately different observers do this, which would matter in the field where substrates vary.

- The reference footprints came from captive animals walking on prepared sand. Only two wild pumas were tested, so field accuracy on natural substrates is not yet shown.

## Cite this summary

Lawrence, K. 2026. Summary of: The challenge of monitoring elusive large carnivores: An accurate and cost-effective tool to identify and sex pumas (Puma concolor) from footprints (Alibhai and Jewell et al., 2017). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2017-alibhai-jewell-challenge-monitoring-elusive-large/