Wildlife Cameras at Organ Pipe Cactus National Monument, 2022

A black-tailed jackrabbit. 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 project aims to detect meaningful changes in mammal communities and populations and give park managers reliable information at several scales.

Key points

• In 2022, 61 cameras at Organ Pipe Cactus National Monument recorded 16 mammal species.
• Knowing how populations change, and why, helps managers protect species now and later.
• Even one year of data yields species-specific insights; at least five years of pooled data are needed for reliable multi-year occupancy models, and the methods are now being developed.

Why cameras, and why occupancy

• Pressures: habitat loss and climate change push many species to shift their ranges. Large protected areas like parks give critical habitat but aren't immune.
• Cameras: non-invasive, covering many species over large areas. Individually marked animals such as jaguars can be counted, but most species can only be identified to species — so SODN tracks occupancy, the share of an area a species inhabits.
• Imperfect detection: a species not photographed may be absent — or just missed. Occupancy models (from 2002) account for that.
• Covariates: 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).

A wildlife camera deployed at Saguaro National Park's Tucson Mountain District. NPS.

Methods

• Cameras: in March 2022, crews set 61 unbaited Cuddeback cameras at established sites — the same places and times each year since 2016 (except 2019, because of the government shutdown). Sites pair with SODN's long-term vegetation and soil plots, laid out in a spatially balanced design, so detailed vegetation data can help explain wildlife patterns.
• Recording: infrared and motion sensors took a photo at any movement or sudden temperature change, from March 11 to April 26, 2022.
• Processing: technicians removed "false triggers," sorted detections in the Colorado Parks and Wildlife Photo Warehouse database, and exported metadata for analysis.
• Helpers: three volunteers and four interns from various parks and partners helped deploy and retrieve cameras.
• Example model: single-season, single-species occupancy in R (unmarked), with detections in seven-day periods. Nine target species were chosen — animals at least 43 cm long (about a rock squirrel) and detected at more than 30% of sites, which excluded rarer species such as bighorn. Covariates were chosen by backward elimination, keeping those with some explanatory power (p < 0.10).

Field crew who set the 61 cameras in 2022. NPS.

What the cameras saw

689 detections: 416 mammals identified to 16 species, 267 identified to order, family or genus, 35 unidentifiable mammals, plus two bird species and three unidentified birds.

• Notable: antelope jackrabbit, bighorn sheep, mountain lion, Sonoran pronghorn, western spotted skunk and white-tailed deer — ecologically important but uncommon or rare here; some turned up at new sites.
• Mountain lion: only the second ever recorded on the monument's cameras (the first in 2020). Home ranges are large and few live within the boundary; they favor higher, rugged country with more food and cover, though they also use the low desert.
• Year to year: annual counts of animal photos have ranged from 575 to 3,738; occupancy modeling should help explain why. There are now six years of data (2016–2022, excluding 2019).

Jackrabbits and slope

Combining black-tailed, antelope and unidentified jackrabbits, the example model found occupancy fell as slope rose: 60–80% on flat ground, under 20% on slopes steeper than 12 degrees. Flatter areas likely offer easier food, water and cover than the monument's rugged, barren steeps — a useful insight for managers from a single season's data.

Jackrabbit occupancy by slope, 2022 (average in green, standard error in gray). NPS.

Why it matters

Multi-year occupancy — often a stand-in for abundance — shows whether populations are increasing, stable or declining, and modeling the influence of temperature and precipitation helps anticipate the effects of climate change.

Sources

Based on "Wildlife Monitoring at Organ Pipe Cactus National Monument," 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. Earlier results: 2021 report.