Armadillo Courtship Is the Joy of the Chase—and the Catch

Instinct drives these armored animals to have sex on the run—and they’ll need to keep running to replenish the ranks of their at-risk species.

This story appears in the July 2018 issue of National Geographic magazine.

The mammal lineage of Xenarthra—sloths, anteaters, and armadillos—has inhabited the Western Hemisphere since Paleocene times, some 65 million years ago. Clearly, they’ve been perpetuating their species, but scientists rarely catch them in the act.

Brazilian ecologist Nina Attias has. She’s spent years studying three of the 20 species of armadillos. Her doctoral research focused on Euphractus sexcinctus, aka the yellow, or six-banded, armadillo (above), whose courtship rituals she has observed and filmed.

In the Pantanal wetlands of Brazil, yellow armadillo amour blooms year-round. When males catch the scent of a female in estrus, they approach, and “she just starts running,” Attias says. “You’ll see a female running like crazy and a bunch of males chasing her.” Once a swift suitor manages to mount the female, “coitus actually happens while they’re running,” Attias says.

Even as other males chase them, the couple stays coupled. It helps that among mammals, armadillos have one of the largest penises relative to body size; an E. sexcinctus male may have a 13-inch-long body and a six-inch-long penis. And if on-the-run sex succeeds, 60 to 65 days later the female may bear one or two pups.

Just procreating won’t ensure armadillos’ survival; they need human help. Brazil has a national plan for conserving three-banded armadillos. The state of Piauí has set aside parkland with the animals’ protection in mind. And with support from the Institute for the Conservation of Wild Animals, where Attias works, the state of Mato Grosso do Sul plans to track giant armadillos as an indicator species, whose presence will help measure the success of habitat conservation efforts.

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