Baltimore (WHTM) It’s early morning at the Maryland Zoo in Baltimore. At the Chimpanzee Forest exhibit, the residents, fifteen chimpanzees, are on the move. If they’re not climbing, they’re running. If not running, they’re walking.

And then there’s Joice, or Joicey to her friends. She moves more slowly and carefully than the other chimps, with good reason. As animal keeper Melissa Somogyi explains, “Joice is special, she is 51 years old and she has arthritis in her hips.”

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51 is quite old for a chimpanzee. Joice is just one of several senior citizens at the zoo, including 48-year-old Anna, an African elephant, and 16-year-old Ceasar, a reticulated giraffe.

Zoologists tend to discuss animal ages in terms of median lifespans – that is to say, if you have X number of animals in a group, half will die before reaching the median age, and half will die after that. In the case of Joice, Anna, and Caesar, their ages are near or well above the median life expectancy for each individual species, which is: 39.4 years for a female African elephant (Loxodonta Africana), 40.2 for a female chimpanzee (Pan troglodytes), and 15.1 years for male giraffes (Giraffa camelopardalis). 

It also means they’re starting to get stiff in the joints, particularly large animals. Zoo staff have developed care plans to help all of them deal with advancing age.

In the case of Joice, this includes daily rounds of physical therapy. We sat in as animal keeper Melissa Somogyi put Joice through her paces using a clicker.

“We use both hand cues and verbal cues,” Somogyi explains. “And when Joice does the behavior that I am asking for I will click, which is a bridge that lets her know that she did the right behavior and her reinforcement is on the way, and her reinforcement is French and mixed nuts.”

A part of Joice’s physical therapy involves stretching her feet up and out sideways, a move that might be somewhat difficult for her in her advanced age, but would be almost impossible for any human short of a trained gymnast or ballerina. Her final exercise-standing up.

“That’s just stretching out her leg muscles, strengthening those muscles, and then she’ll stretch her hips out in another position to stand up again,” explains Somogyi. “So those are all of the stretches that Joyce does on a daily basis. And we have seen an increase in her mobility since we started this routine. She definitely gets around better than she did. And Joyce also has a lot of choice with her mobility.”

Zoo staff let Joice make a lot of her own choices. “So some days, if she’s not feeling well and she chooses not to come out to the outdoor gym, we’ll give her some time and a smaller space. We also will give her time with a less dynamic group of maybe some of our older individuals if she just seems like she’s not moving around well. And then she also gets a joint supplement and then she’ll get ibuprofen as needed if she seems stiff.”

“In human care, female chimps can live into their fifties and their sixties, and Joyce is otherwise very healthy. So with these treatments, and she seems to be moving around, we’re hopeful to have definitely some good more years with Joice.”