LINCOLN, Neb. (AP) - For months, the two zookeepers played a high-stakes game of monkey-see, monkey-do.
The pair was leading a team at the Lincoln Children’s Zoo that had no choice but to hand-feed and hand-rear a critically endangered black-headed spider monkey - something that hadn’t been done for nearly three decades.
Tonnie had weighed slightly less than a pound when she was born May 31 inside the zoo’s Secret Jungle to Lola and Carlos, a pair of adult spider monkeys that moved to Lincoln for the zoo’s expansion in 2019.
Lola had never given birth before. And lead keepers Kim Jacobson and Tori Reynolds had never cared for a pregnant spider monkey before.
So they talked to experts at other zoos. “We asked: What are things to look for, especially as Lola’s pregnancy is progressing?” Jacobson told the Lincoln Journal Star. “When can we expect to have a baby? What are the behavioral signs and physical changes to look for?”
But their research was just beginning. They had kept a close watch on mother and daughter after Tonnie’s birth, monitoring how much time they spent feeding and sleeping, how much weight the newborn was gaining. And by the end of the first week, it became clear Lola wasn’t producing enough milk to meet Tonnie’s needs.
They tried to help, hoping to supplement the newborn’s nourishment. But they needed Lola there, and the bottle frightened her; the zoo’s spider monkeys had never seen one before, Jacobson said.
They knew they were running out of time. “The baby was at a weight where we needed to make some kind of decision about her care,” Jacobson said.
They consulted with the zoo’s veterinarian staff and the Spider Monkey Species Survival Plan, a cooperative of zoos that dictates the distribution of animals in captivity - and their breeding programs - to try to keep their genetics diverse.
The decision? Jacobson and Reynolds would take over Tonnie’s early upbringing. But that meant a large and long commitment: Not only would they have to nourish a growing monkey, but they’d also have to teach her how to be a monkey.
They looked for guidance, and found the last time someone had hand-reared a spider monkey was nearly 30 years ago - a Chicago zookeeper who published a paper about it in 1993.
They relied heavily on that, and then on the air mattress the zoo inflated inside the Secret Jungle. The two keepers and their team took turns sleeping at the zoo, giving Tonnie 24-hour care.
“It was like taking care of a baby,” Jacobson said. “You have to get up and warm the bottle. If she wanted to play at 3 a.m., you do what you have to do. Anytime she needed social interaction, we had to provide it to her.”
For the first several weeks, Tonnie required a dozen feedings a day, which could last 30 minutes to an hour.
They gave her more than warm formula, regular baths and a stuffed monkey she still clings to. They needed to prepare her to join the three other adults when she was ready.
They started by building what they called a baby climber - soft blankets with low-hanging ropes, branches and toys - to urge movement and muscle development. They worked with her to use her tail to climb, and then they made the structures more complicated.
The two tried to copy monkeys being monkeys. “We observed how the adults played, vocalized and wrestled and attempted to simulate it as much as we were able to.”
The humans nailed the common greeting gesture: Cheeks sucked into a kiss face, chin pushed out. When they attempted to teach spider monkey sounds, though, they found playing YouTube clips to her was more effective.
But more importantly, they kept Tonnie as close to the other adults as they could.
“We thought that having them next to her would give her a much better chance at learning those necessary social skills for integrating back into the group.”
At first, Tonnie could see and hear the others through glass. Then she could touch them through mesh.
And when she was old enough, and her climbing skills were strong enough, they thought it was time to meet her family.
But there was some risk of rejection - or even aggression. “Spider monkeys can be flighty animals, and they can be unsure and nervous of things.”
They started by putting her in with Lola, hoping they’d sense their familial bond, and that the other adults would see them interacting. It’s not clear if Lola recognized Tonnie as her daughter, but she at least accepted her as another monkey, a member of their troop.
Then it was time to add Carlos and her half-aunt, Aliena, the oldest of the adults.
“Removing that barrier was scary for us,” Jacobson said. “And we were so pleasantly surprised by how the adults took her under their wing and it became very normal, very quickly.”
Aliena, who has experience with infants, has taken a protective and almost maternal role, allowing Tonnie to ride around on her back. And Carlos, who’d shown the most interest in the newborn during her hand-rearing, likes to teach her how to play.
Tonnie’s human team stopped sleeping at the zoo in October. She’s up to 5 pounds and down to two feedings a day, and spends most of her time with her troop.
But she still knows her mother figures and will come running up to the glass when she spots Jacobson and Reynolds on the other side.
“It’s pretty cool and it’s pretty special,” Jacobson said. “But our main goal is that she doesn’t recognize us and just becomes a monkey.”
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