Chalupa and Bosco, the Cheyenne Mountain Zoo's resident male and female sloths, haven't shown any signs of attraction in the nearly four years they've been hanging out together in the Monkey Pavilion.
So zookeepers were "pleasantly surprised" when they found out Chalupa, a Hoffmann's two-toed sloth, was pregnant during an unrelated checkup two months ago, said zoo spokeswoman Rachel Wright.
The 19-year-old sloth gave birth early Tuesday afternoon to a baby that appears healthy, the zoo said in a news release.
Visitors can see the mother and her kin at the pavilion, where they're being kept in a temporary enclosure that gives them more privacy, according to the news release.
In a few months, once zookeepers and veterinary staff agree it's safe, the pair will be released to roam the ropes and hammocks that line the pavilion with 27-year-old Bosco.
Zookeepers won't know the baby's gender for months and don't have a plan to name it, according to the release.
Maternal instincts are kicking in for the first-time mother. Her newborn is clinging to her and nursing, Wright said.
"It’s a good sign that she and the baby are bonding well," she said.
A sloth was last born at the zoo 15 years ago, Wright said.
Zoo staff suspect that Bosco and Chalupa, both nocturnal mammals, may have mated after hours.
Hoffmann's two-toed sloths are native to tropical rainforests in Central and South America, according to the zoo website. They spend most of their time upside down and feast on fruit and leafy greens in captivity, the website states.
The breeding process takes longer for the slow-moving species than for other animals, Monkey Pavilion Animal Care Manager Joanna Husby said in a statement.
"This baby was worth the wait, though," Husby said.