Trampled: The Endangerment of The San Rafael Cactus

San Rafael Cactus

By Steven Nguyen

Description and Ecology:

Average size of a San Rafael cactus.
Image from Utah Division of Wildlife Resources

The San Rafael cactus, or Pediocactus Despaninii, is a small barrel shaped cactus. These cacti are very small, only growing up to 2 inches tall, and up to 4 inches wide. They are generally noticeable for a short time during the spring in the San Rafael Swell, located in Utah.

Geographic and Population Changes:

The San Rafael Swell is an area that shelters many plants found nowhere else in the world, including the San Rafael cactus. The species range is centered on the San Rafael Swell and extends into the southwestern Emery County of Utah. The cactus has five known populations: the Massentuchit, McKay Flat, Short Canyon, and Ferron. They are generally found growing on benches, hill tops, and slopes. The documented population size of the San Rafael cactus is 4,300 individuals; however, the United States Fish and Wildlife Service (USFWS) estimates the total population to be about 20,000 individuals distributed across the five known populations. Population studies conducted by the USFWS indicates that the population is continuously declining (Recovery Plan for San Rafael Cactus). 

Species range in Emery County.
Image from U.S Fish and Wildlife Service

San Rafael Swell in Utah.
Image from Utah Travel Industry

Listing Date and Type of Listing:

With continuous population decline, The San Rafael cactus was officially listed in the Endangered Species Act (ESA) as an endangered species on October 16, 1987.

Cause of Listing and Main Threats:

The endangerment of the San Rafael cactus can be attributed to a variety of factors, but most notable are the over-collecting by enthusiasts and disturbances in its habitat. The small, restricted population of the species make them highly vulnerable to these effects.

Since the San Rafael cactus exists primarily only in the San Rafael Swell, it is quite rare and highly desired by cactus collectors and gardeners. The species is frequently sought by both hobby and commercial cactus collectors. The National Park Service (NPS) and the Bureau of Land Management (BLM) both restrict the collection of the cactus, but enforcement is difficult when the populations are scattered over unpopulated and remote Emery County (Recovery Outline for San Rafael Cactus).

Habitat disturbances from off-road vehicles.
Image from Four Wheeler Network,
a site for off-road hobbyists.

Habitat disturbances are primarily caused by off-road vehicles passing by and livestock grazing in the San Rafael Swell. Off-road vehicles passing by diminishes the San Rafael's cactus' ability to successfully reproduce. The cactus forms flower buds on their surface and are vulnerable to the flying debris caused by passing vehicles (Recovery Outline for San Rafael Cactus). A 1986 Desert News article expresses support of limiting off-road vehicles in the San Rafael Swell to save the cactus populations. Additionally, livestock grazing produces detrimental effects on the cactus by changing the population structure and fostering the spread of invasive weeds. Cheat grass, or bromus tectorum, have occurred within the San Rafael's cactus' habitat, and are currently a threat as increased competition, especially for water (Recovery Outline for San Rafael Cactus).

Recovery Plan:

The recovery plan for the San Rafael cactus has a vision to sufficiently reduce the threats and ensure the high probability of survival for the San Rafael cactus. Two goals to achieve the recovery plan's vision include maintaining viable populations of the species and initiating recovery measures (San Rafael Cactus: Pediocactus Despainii). The recovery plan outlines numerous actions to achieve these two goals, consisting of:

• Preventing the collection of San Rafael cactus from their natural populations.
• Surveying suitable habitat and locate additional populations.
• Implementing ecological studies and monitoring to better understand the species.
• Identifying sites in urgent need of habitat conservation and establishing formal management designations.
• Increasing public awareness of the San Rafael cactus through education efforts.

Work Cited:

U.S Fish and Wildlife Service. (2007). Recovery Outline for San Rafael Cactus (Pediocactus despainii) and Winkler Cactus (Pediocactus winkleri). Denver, Colorado. Retrieved from http://ecos.fws.gov/docs/recovery_plan/San%20Rafael%20&%20Winkler%20Cacti%20Recovery%20Outline_2.pdf

U.S Fish and Wildlife Service. (2013). San Rafael Cactus: Pediocactus Despainii. Denver, Colorado. Retrieved from http://www.fws.gov/mountain-prairie/factsheets/San%20Rafael%20Cactus%20Fact%20Sheet_061913.pdf