Arizona Cacti Garner Endangered Status

WASHINGTON (CN) - The Acuña cactus and the Fickeisen plains cactus have been listed as endangered under the Endangered Species Act, according to the U.S. Fish and Wildlife Service. The critical habitat designation for the plants is promised later in the year.

The listing was fast-tracked due to a 2011 settlement between the USFWS and the Center for Biological Diversity (CBD) that resulted in a court-approved five-year workplan to speed listing decisions for hundreds of species across the nation, the CBD said in its press release.

"The rare cactuses have been on a waiting list for federal protection for many years - 32, in the case of the Fickeisen plains cactus," the group said.

The Fickeisen is less than 3 inches tall, about as big around as a quarter, and has a beautiful yellow and white flower. It grows only on the Kaibab limestone of the Colorado Plateau.

Its populations are widely scattered over a broad range and are often separated by many miles and varying topography. "Although there is abundant suitable habitat within its range, many areas are unoccupied by the plant for reasons unknown," the action said.

Although 33 populations have been documented, the majority of them are small in number, some having fewer than 10 individual plants.

The Fickeisen is threatened by habitat destruction from livestock grazing combined with small mammal predation and the effects of climate change such as drought. Small population size worsens the effects of these threats. Declines in overall population numbers reflect a reduction in reproductive adults and few to no seedlings. "The continued loss of reproductive adults without adequate recruitment poses a significant and immediate risk of extinction to the species throughout the species' range, and is not restricted to any particular significant portion of that range," the rule noted.

In contrast, the spherical Acuña cactus grows up to 16-inches tall, usually with only one stem, and it has pink or lavender flowers. It is found in Maricopa, Pima and Pinal Counties in southern Arizona and in Sonora, Mexico. Much of its habitat is already on federal, state or tribal lands.

The Acuña faces severe threats from drought and climate change, combined with native insect and small mammal predation, invasion from nonnative plant species and habitat destruction from United States-Mexico border activities.

"More than 84 percent of the known living Acuña cactus individuals occur within 16.5 km (10.25 mi) of the border," according to the listing action.

A vehicle barrier and a pedestrian fence have reduced activity in the area, and the U.S. Customs and Border Protection "has begun efforts to educate Border Patrol agents on the locations and appearance of Acuña cactus so that the areas that support the plant can be avoided to the maximum extent possible," the USFWS said.

Extreme weather events due to climate change are likely to affect long-term survival and distribution of the cactus. Plant census results from 2011 to 2013 noted high numbers of dead plants and low numbers of juvenile plants. Even though cactus are able to survive heat stress better than other plant species, "[e]xtreme temperatures can, however, negatively impact seedling survival in many Sonoran Desert plants, and drought coupled with high temperatures lessens temperature tolerance in seedlings," according to the rule.

"[T]he drought the southwestern United States has been experiencing since the late 1990s is the worst in more than 100 years and is being exacerbated by record warming."

The proposed rule included 161 square miles of proposed combined critical habitat for the cacti. That final designation is expected later this year.

The listing is effective Oct. 31.

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