The U.S.-Mexican border might inspire images of sun-bathing snakes and lolling lizards, but the region also offers a wealth of other wildlife, from owls to big cats.
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CACTUS FERRUGINOUS PGYMY OWL
Glaucidium brasilianum cactorum
Don’t let its diminutive stature deceive you: At just under 7 inches, the cactus ferruginous pygmy owl—one of three subspecies of the ferruginous pygmy owl—is a feisty fellow capable of snagging prey three times its size, such as quail and doves. “They’re actually pretty nasty,” says Aaron Flesch, a senior research specialist in the School of Natural Resources at the University of Arizona. During the summer, however, more than half of the owls’ diet in Arizona consists of lizards, like whiptails and tree lizards. The yellow-eyed, reddish-brown owls make their nests in saguaro cacti, where they’ll lay a clutch of two to six eggs and fledge three or four chicks.
Although the cactus ferruginous pygmy owl was removed from the endangered-species list in 2006, owl populations number only in the dozens in Arizona (not counting those living on Native American reservations), where their habitat is naturally fragmented and birds are distributed in clumps of six to eight, separated by a few kilometers. Bird numbers are higher in their Mexican range, which spreads south through the states of Sinaloa and Sonora.
The eastern subspecies ranges from southern Texas and Tamaulipas state, to the remaining states in Mexico. The third subspecies lives in South America. According to Flesch, the birds in Texas seem to be faring better than their Arizona counterparts, numbering in the hundreds and can be found in water ranchlands. “They got a lot more habitat there,” he says.
Despite being the largest cat in the Western Hemisphere, the jaguar is an elusive phantom of a feline. Thought to be extirpated from the United States by the 1970s, it wasn’t listed as an endangered species until 1997, following several 1996 sightings in the Southwest.
Jaguar range includes parts of southern Arizona, New Mexico, and possibly Texas, and extends through Mexico, Central, and South America. However, that range has been reduced by more than 50 percent of its historical size. The total number of jaguars throughout their range is unknown.
When it comes to food, jaguars aren’t particularly finicky and will feed on larger animals like deer, as well as smaller creatures, like skunks. Jaguars are keenly camouflaged with attractive spots called rosettes, which make them difficult to see in mottled shade. They’ve been sighted in a variety of environments, including grasslands, forests, and other dry habitat types.
The Borderlands Jaguar Detection Project is the only study being conducted in the United States on jaguars. Remote sensing cameras placed in small mountain ranges and riparian areas along the U.S.–Mexican border detect heat generated by the motion of any animals passing by; these have allowed the Borderlands Jaguar Detection Project to pick up at least 26 photographs of jaguars in the area. According to Jack Childs, the project’s coordinator, there have been at least four jaguars accounted for in the United States since 1996; those are likely part of a thinly scattered population spreading into Mexico.
DID YOU KNOW: A jaguar rosette differs from a leopard spot in that it surrounds one to three smaller dots; leopards’ spots are empty or solid black.
Antilocapra Americana sonoriensis
The Sonoran pronghorn is one of five subspecies of pronghorn. Only one wild population exists in the United States—in Arizona, where approximately 70 individuals roam on a million acres of habitat, including land in Organ Pipe Cactus National Monument, the Goldwater Air Force Bombing Range, and the Cabeza Prieta National Wildlife Refuge. Two other wild populations, totaling about 600, exist in Mexico.
As browsers, Sonoran pronghorn require nutritious forage; however, they’re not fickle and will eat nearly anything growing in the desert, according to John Hervert, a biologist and wildlife program manager of the Arizona Game and Fish Department.
The fundamental threat facing Sonoran pronghorn—an endangered species—is drought. In 2002 the species’ range in Arizona was hit by a devastating drought, causing the population to plummet to about 20 animals, or a sixth of its former size. Since then researchers have been reviving the population through aggressive management projects, including a captive breeding program at the Cabeza Prieta refuge, where there are now 37 individuals. This year marked a sign of hope, when four males from the program were released into the wild: “They’re still alive and well,” says Curtis McCasland, the assistant refuge manager at Cabeza Prieta. The refuge plans to release more next year.
DID YOU KNOW: Pronghorn are the only truly endemic ungulates in North America—and they’re also the fastest land mammals on the continent. They likely developed their speed to evade predators that no longer exist in North America—namely, a New World relative of the cheetah.
Leopardus pardalis albescens
With their big eyes and cream-colored fur, patterned with black-rimmed, reddish-brown spots, ocelots are beautiful wild cats. Those living in the United States are part of one endangered subspecies restricted to about 80 individuals in Texas—specifically in the Laguna Atascosa National Wildlife Refuge, and possibly private ranches surrounding the area. This subspecies also occurs in Mexico, around the state of Tamaulipas.
Ocelots are carnivores, with a diet consisting of rabbits, small rodents, and birds, and they favor thick brush that’s difficult to penetrate, such as thorn brush. The greatest threat facing ocelots is habitat destruction, although collisions with vehicles is also a problem.
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