Exploratory Use of Track and Camera Surveys of Mammalian Carnivores in the Peloncillo and Chiricahua Mountains of Southeastern Arizona

1. What they did

Carnivores are hard to study because they live at low densities, are mostly active at night and are wary of people, so basic facts about where they live are often poorly known. The authors tried two non-invasive methods, track stations and remote cameras, to gather baseline information on the carnivores of the Chiricahua and Peloncillo mountains of southeastern Arizona. These ranges are part of the Madrean “sky islands” and could receive Neotropical cats moving north from Mexico.

• Track stations. They set one transect in each of six canyons (four in the Chiricahua Mountains, two in the Peloncillo Mountains), each with 10 stations 400 m apart along the main drainage, near the streambed and on animal trails where possible. Each station was a circle of sifted gypsum powder about 1 cm deep and 1 m across, with a rock daubed with two scent lures in the middle. Some stations also had visual lures (hanging feathers, dead birds or balls of white cheesecloth) to attract cats. Stations were checked daily for 5 days between 1 March and 21 May 1999.
• Identifying tracks. Tracks were identified using three field guides (Murie 1954, Halfpenny 1986, Rezendes 1992). Striped, hooded and hog-nosed skunk tracks could not be told apart, so they were pooled as “large skunks”; deer, rodents, rabbits and hares, lizards and birds were also pooled.
• Cameras. Infrared-triggered cameras were set at 18 stations for a total of 150 camera days, on likely carnivore routes: riparian corridors, trail crossings, trails to water or through thick brush, and mountain passes. Most had a scent lure 2 to 3 m in front and many had visual lures.
• Indices. For tracks, the number of visits divided by track nights; for cameras, the number of photographs divided by camera days.

2. What they found

Overall

• Track stations recorded 241 detections and cameras 149, of carnivores and other vertebrates.
• Combined detections: gray fox 112, white-nosed coati 33, large skunks 25, ringtail 13, domestic dogs 13, coyote 9, cougar 7, bobcat 3 and western spotted skunk 2. One American black bear was photographed in the Chiricahua Mountains.
• Other animals: rodents 83, birds 33, lizards 22, cattle 12, rabbits and hares 12 and deer 10.

Track stations

• At least 8 carnivore species, most often gray fox, which was found on all six transects.
• The two Peloncillo transects had the most native carnivore species (7 in Skeleton Canyon, 5 in its South Fork). The Chiricahua transects had 2 or 3 each.
• Deciduous riparian forest (26 stations) gave seven carnivore species, and cougar, coyote and western spotted skunk tracks were found only there. Madrean evergreen woodland (26 stations) gave four.
• Bobcats were not recorded at track stations, only on camera.

Cameras

• In order of number of photographs: gray foxes, white-nosed coatis, ringtails, cougars, large skunks, bobcats, coyotes and one American black bear.
• Gray foxes were photographed in every habitat surveyed by cameras.
• Two cameras malfunctioned, so their indices are not accurate.

No Neotropical cats

Neither method found evidence of jaguars or other Neotropical cats.

3. What they concluded

• Within several weeks, track and camera methods together detected a variety of carnivores and their prey across a range of habitats.
• The surveys give preliminary information on distribution, activity and habitat associations that could guide future surveys in the region.
• Both methods show presence and activity, not reliable absence. Because individual animals were not identified, track surveys give a relative measure of activity, not population size. The lures may have changed visitation rates between species, stations and habitats, limiting comparisons.
• Future surveys could combine track and camera methods with occupancy modelling, identifying individuals from natural or added marks in photographs, or analysing how visits are related between stations, to estimate detection probability and population size.
• Not finding Neotropical cats does not mean they are absent, given their low density and the limited sampling; jaguars have recently been seen in the region.
• Frequent detections in deciduous riparian forest show how important riparian areas are as homes and travel routes for wildlife in the arid Southwest.

4. How tracking was or was not used

Tracking was one of the two main methods. Footprints left in gypsum powder at baited track stations were identified to species or group each day for 5 days, using field guides. The track index counted visits per station night. No trailing was reported. The authors note the limits of the method: some species (striped, hooded and hog-nosed skunks) could not be told apart by tracks alone, rain stopped the gypsum stations working for 2 days in Cottonwood Canyon, and passerine birds were not recorded because they were hard to identify.

5. Tracker or observer certification

Not reported. The paper does not say who identified the tracks or how experienced they were, only that identification was based on three field guides. All species records from the track stations depend on these identifications.

6. Other technologies, skills or innovations

• Gypsum powder track stations with commercial scent lures (Russ Carman’s Pro’s Choice and Canine Call) and visual lures.
• CamTrakker remote cameras with passive infrared sensors (heat and motion), automatic focus and flash, date and time stamps, and a 3-minute delay between pictures to avoid repeated shots of the same animal.

7. Implications for conservation (from the paper)

• Riparian areas act as linear oases in the arid Southwest and are important resident and travel habitat for carnivores and other wildlife.
• The sky island ranges could receive Neotropical cats from populations to the south, so short surveys that miss them do not rule them out.