On a Costa Rican beach where the jungle meets the sea, the recorded cries of a lost baby sloth recently blasted from a loudspeaker.

Volunteers from the nonprofit Jaguar Rescue Center had hiked Playa Cocles for hours, broadcasting the sounds in hopes of enticing the infant’s mother to reclaim her little one.

Tourists had found the baby lying on the beach the day before, covered in sand and ants, and brought it to the center. A vet check revealed the brown-throated three-toed sloth, the weight of a can of soup, was in a few weeks old and in good condition. But the youngster would not have survived the night alone on the beach. (See unbelievably cute pictures of rescued baby sloths.)

A visual search for the mother proved fruitless. Knowing that sloth moms recognize their babies' cries, the center's founder and resident biologist Encar Garcia recorded the orphan’s vocalizations on her smartphone, transferred the files to a portable speaker, and sent a team back into the wild the next day.

Around 5 p.m., the volunteers noticed a curious adult sloth descending a tree.

“The volunteers were very excited and said, ‘We got one that’s climbing down, and looking around like crazy,'" says Garcia, who wrapped the baby in a towel and raced to the scene with veterinarian Fernando Alegre.

He lifted the animal up to the waiting sloth, which immediately accepted the baby. The two then shared a nuzzling embrace that brought the rescuers to tears, Garcia says.

Sloth Dangers

Mother brown-throated three-toed sloths generally have one baby at a time, which they care for until they're six months old.

This female, which would not have felt comfortable on the ground, likely used her keen sense of smell to confirm the baby’s identity, and then hid her face to minimize contact with humans, says sloth expert Monique Pool, director of Green Heritage Fund Suriname.

“I applaud what the Jaguar Rescue Center did, because the babies have a much better chance of surviving with their mother,” Pool said by email. (Why it's a myth that slow-moving sloths are stupid.)

The episode shows the perils of growing up sloth at the edge of the jungle, adds Sam Trull, director of the Sloth Institute, a wildlife rescue center on Costa Rica’s Pacific coast.

Many sloths are electrocuted by power lines, killed by cars and dogs, and displaced by habitat destruction as seemingly harmless as trimming trees. And, even under the best of circumstances, a clumsy baby can always fall out of a tree, she says.

Though brown-throated three-toed sloths are not threatened by extinction, it "doesn't mean they are not in danger," Trull says.

A Sound Plan

Garcia says that broadcasting sloth baby cries is a tried-and-true technique that has worked before.

“One time I had the baby for eight days,” she says. “Eventually we were able to find the mother.” (Watch how sloths slowly navigate the world.)

In 2017, her rescue center took in 150 orphaned or injured sloths; so far in 2018, there's been at least a hundred. Raising a baby three-toed sloth is a special challenge, in part because the leaves they like to eat are difficult to get, she notes.

But the benefits are worth it. Even after 17 years on the job, Garcia is still moved by the tender scene she witnessed on the beach that day.

“For me,” she says, “it was like the first rescue all over again.”