The Use of an Orthotic Casting Foam as a Track-Plate Medium for Wildlife Research and Monitoring

1. What they did

Track plates are a cheap and gentle way to learn which animals are using an area, but most track-plate media fail in rain, heavy dew or even fog, and hard surfaces such as sooted aluminum give only flat, two-dimensional prints. Rain shelters help, but they cost money and can change how animals behave. The authors tested Biofoam, a non-toxic phenolic foam made for taking casts of human feet for orthotics, as a waterproof medium that could record three-dimensional tracks.

• Lab trials (August and September 2005). At an animal shelter in Prince George, four dogs, three cats, a rabbit and a rat walked over plates of about 60 x 90 cm made of casting foam (2 cm thick, taped to plywood), coarse sand, fine sand, very fine sand and sooted aluminum, set flush with the ground in dog runs. The best track from each animal on each medium was photographed.
• Animal responses. They filmed the first minute or so of each animal’s approach to the plates. At a wildlife shelter in Smithers they also placed foam plates in a cougar and black bear paddock and a guinea pig and rabbit pen, and watched for 20 to 30 minutes.
• Expert questionnaire. The photographs were sent to people who had published on wildlife tracking or had extensive tracking experience (such as tracking instructors or trappers). They rated each track from 1 (low quality) to 10 (high quality) and could explain their ratings.
• Field trial (3 to 24 October 2005). Six foam plates were set on wildlife trails, a fallen log and a beaver dam in the Aleza Lake Research Forest.
• Extra tests. Running tap water over a tracked foam plate for 10 minutes, and freezing a tracked plate at -20 °C.

2. What they found

Track quality

• Only five experts replied, so only means and standard deviations are reported.
• Foam and sooted aluminum gave the best tracks overall; all three sands did poorly by comparison.
• Foam was rated highest for six of the nine animals. Sooted aluminum was rated higher for one dog and two cats (Cat 3, the smallest at about 0.25 kg, scored 4.8 on foam and 8.4 on soot).
• Average dog scores: foam 8.03, sooted aluminum 6.6. Average cat scores: foam 7.46, sooted aluminum 7.83.
• The experts noted that foam registered claws and clearly showed all pads and the negative spaces between them. Sand outlines looked blurry and enlarged. One expert said they could picture the animal’s foot when looking at the foam tracks.
• Foot hair was sometimes pinched and pulled out by the foam.

Animal responses

• Dogs ignored the foam but all stopped to sniff the sooted aluminum, which the authors put down to the smell of the acetylene soot.
• Two of the three cats seemed wary of the sinking feeling of the foam and pulled their paws back.
• A cougar of about 90 kg walked over the foam again and again as if it were not there.
• A black bear left prints only after sniffing, scratching and breaking up some of the foam. Rabbits and guinea pigs stepped on it reluctantly after sniffing and nibbling small bits.

Field trial

• Tracks of moose, red squirrel, porcupine, pine marten or fisher, beaver and merganser ducks were found on the plates. Most were of high quality; the pebble-like texture of a porcupine’s foot pad was clearly visible.
• On a fallen spruce, red squirrels trampled one plate with hundreds of overlapping tracks that were hard to tell apart. On a beaver run at about 45°, most of the foam was knocked off the board.
• About 30 cm of rain and temperatures from -5 to +18 °C did not seem to affect the plates or tracks, apart from tiny dimples, probably from hail, on one plate.
• Running water and freezing did not harm the tracks, and the foam still took new prints afterwards.

3. What they concluded

• Casting foam generally captures higher quality tracks than sand or sooted aluminum, and records the true shape and size of the foot, which matters because track measurements are used in identification. Two-dimensional prints from soot should be measured with caution.
• Foam plates stood up to heavy rain, hail and freezing without a rain shelter, so they avoid the behavioural bias that covers can cause.
• Weaknesses: tracks can be lost to trampling, as with other media, and plates need a level surface or the foam can be knocked off.
• Some animals were wary of the foam, so caution is needed when using it to detect natural behaviour or movement. All test animals were domestic or captive; the authors suggest checking for bias in wild animals with a second, independent method.
• Foam plates are cheap (about US$3 per plate, US$2 to replace the foam), simple to build with foam, lumber and duct tape, light to carry, need little maintenance, and the tracks can be kept for later reference. They recorded animals from guinea pigs (500 to 1000 g) to moose (400 to 500 kg).
• The authors recommend more rigorous field testing and that ecologists begin using foam where they want high-quality three-dimensional tracks or need to monitor in rainy places without shelters.

4. How tracking was or was not used

The study is about a medium for recording footprints. Experts in wildlife tracking judged the quality of the tracks from photographs, and the field plates were read for the species that crossed them. The authors stress that clear claws, pads, negative spaces, shape and measurements are what make tracks identifiable. No trailing was involved.

5. Tracker or observer certification

Reported but not validated. The five experts were chosen because they had published scientific papers or books on wildlife tracking, or had extensive tracking experience (such as tracking instructors or trappers). They are not named, and no certification or test of their skill is reported. The paper also does not say who identified the species on the field plates.

6. Other technologies, skills or innovations

• Biofoam orthotic casting foam (Smithers Bio-medical Systems) as a track-plate medium, cut to 2 cm thick with a hacksaw blade and taped to half-inch plywood.
• Sooted aluminum plates made with an acetylene torch modified to give more soot.
• Digital macro photography of tracks (6.3 megapixel Fuji Finepix S6000fd).
• Video of animals approaching the plates.

7. Implications for conservation (from the paper)

• Track plates are a cheap, non-intrusive way to survey animal presence, relative abundance and activity over large areas. A waterproof medium that needs no rain shelter could make them usable in wet places and seasons and lower costs.
• Researchers should keep survey devices from biasing animal behaviour; wariness of the foam in some species needs testing in wild animals.