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Acuña cactus Echinomastus erectocentrus acunensis
ESA status: endangered

Acuna_cactus pc Hank JorgensenIt’s hard to make a living in the desert. The acuña cactus, despite being adapted to the dry conditions, is finding it more difficult all the time. This stocky plant grows to about 16 inches tall, all of those inches decorated with maroon spines and a flourish of lavender, rose, or pink flowers in spring. It is found on gravel ridges and knolls in the Sonoran Desert in Arizona and Sonora, Mexico. Despite its capacity for desert survival, populations of the acuña cactus are disappearing. Organ Pipe Cactus National Monument (OPCNM) lost 95 percent of their acuña cactus population across 1000 acres of habitat between 1991 and 2010. In populations that have been surveyed more than once, nearly 80 percent mortality has been documented, even on protected lands with ongoing efforts to manage for the cactus.

In addition to the usual difficulties of desert living, the acuña cactus faces some extraordinary challenges. Extensive, prolonged drought is likely responsible for most recent population declines. But this desert is “hot” in more ways than one. The OPCNM, home to the largest population of the cactus, is also a major travel corridor for smuggling and illegal immigration. Border patrol has a heavy presence in the area. Monument staff cannot get out to monitor acuña cactus without a law enforcement escort. The routes for immigration and smuggling change constantly within the monument, making it difficult to predict the effect of either human or off-road law enforcement vehicle traffic on the cactus.

Parasitism by the cactus weevil and cactus longhorn beetle contribute to the plant’s decline, and climate change could lengthen the breeding cycle for these insects, exacerbating the problem. A mysterious event in 1996 left plants in the OPCNM, the Coffeepot Mountains, and the location near Ajo uprooted and lying on the ground. Whether it was a result of intensive insect predation, thrashers (a bird), javelinas, human vandals, or something else is still unknown, but whatever it was destroyed nearly half the plants in monitored plots. In 2011, surveys again found both living and dead plants uprooted and toppled in every population visited. A large proportion of those remaining were in deteriorating health, blackening from the base upwards, and few new seedlings have been documented; seedlings depend on summer rainfall and soil moisture. Declining rainfall, increasing insect attacks, warmer and drier winters, and persistent drought conditions are pushing this rare cactus into a precarious position. WildEarth Guardians is working to give the acuña cactus a helping hand through challenging times.

photo credit: Hank Jorgensen