Wildlife Cameras at Chiricahua National Monument, 2021

A coyote investigates a wildlife camera. NPS.

The NPS Sonoran Desert Network (SODN) monitors medium and large mammals with remote camera traps at parks across the Sonoran Desert and Apache Highlands. Begun in 2016, the monitoring aims to detect significant changes in mammal communities and populations over time, giving park managers reliable status and trend information.

Why monitor

• Pressures: habitat loss and climate change force many species to shift their ranges; large protected areas like parks provide critical habitat but aren't immune.
• Cameras: non-invasive, recording many species at once over large areas. Animals with unique markings (like jaguars) can be counted individually; most can only be identified to species, so SODN uses occupancy modeling instead.

Occupancy modeling

Occupancy is the share of an area a species inhabits. A camera that sees a species marks it present; one that doesn't may mean absent — or just missed. Occupancy models (developed since 2002) correct for imperfect detection.

• Covariates explain the patterns: fixed factors like elevation may shape where a species lives; changing ones like temperature or rain may affect whether it's seen (animals are less active in heat).
• For managers: multi-year occupancy — often a stand-in for abundance — shows whether populations are growing, stable or declining, and how climate factors affect them.

A wildlife camera at Chiricahua National Monument. NPS.

Methods

• Cameras: in May 2021, crews set 41 unbaited cameras at permanent, spatially balanced locations — the same spots and settings as in earlier years.
• Triggering: infrared and motion sensors fired a photo at any movement or sudden temperature change, from May 10 to July 2, 2021.
• Processing: technicians removed "false triggers" (no animal), sorted the detections with the Colorado Parks and Wildlife Photo Warehouse database, and exported metadata for analysis.
• No volunteers: citizen scientists usually help, but not in 2021 because of COVID-19.

Example model: a single-season, single-species model in R (package unmarked), with detections grouped into seven-day periods. Candidate species had to be at least 43 cm long — about a rock squirrel — to be reliably identified, and detected at more than 30% of sites. Covariates were chosen by backward elimination, keeping those with some explanatory power (p < 0.10).

The field crew that set the 41 cameras in 2021. NPS.

What the cameras saw

1,123 detections: 1,037 of mammals identified to 13 species, 56 identified to genus or family, 8 unidentifiable mammals, plus three bird species and one reptile.

• New at 13 sites: at least one species not seen there before — more wildlife activity at those spots.
• Mountain lions: 27 detections, the most in SODN's monitoring.
• Turkey vulture: common overhead, but rarely caught on camera.
• Record so far: cameras have run at the same sites every year since 2017 (except 2020); annual counts have ranged from 1,210 to 4,293 animal photos. This year's cameras ran in a new time window.

Deer and elevation

White-tailed deer occupancy falls with elevation in the monument (average in green, standard error in gray). NPS.

In the monument's lower areas, white-tailed deer occupancy is high (80–100%); above 2,100 meters it drops below 20%. Lower ground likely offers easier food, water and cover than the barren, rugged, steep heights. Even one season's data can tell managers how deer use the monument.

Sources

Based on "Wildlife Monitoring at Chiricahua National Monument, 2021," prepared by Elise Dillingham and Alex Buckisch, Sonoran Desert Network, National Park Service (PDF), citing MacKenzie and others (2002, 2006, 2018) and other studies; a work of the United States government in the public domain.