When lemurs age, their movements become slower and more rigid. They swing on branches that they could easily grab before. Sometimes the tooth comb, a group of teeth used for cleaning, falls out, making it more difficult for them to keep the fluffy hair on their own. Therefore, the best companion for a geriatric lemur is another geriatric lemur, someone who does not want to move, but is content to sit together and help with cleaning. “Young people can be very turbulent,” said Grebe.
To his credit, Cheyenne is never satisfied with any geriatric lemur. A while ago, the keepers tried to introduce Martine, a female lemur with a collar, to Chloris and Cheyenne. Chloris did not care – a warmth perhaps helped by his falls. “She doesn’t care how things look,” said Keith. But Cheyenne showed her teeth, looked at the new lemur and finally expelled it. Mrs. Keith said that Cheyenne could be bossy, but that Martine was notoriously rebellious: “She was not transmitting the right vibes to Cheyenne.”
Still, Cheyenne and Chloris are open to elderly singles who join their enclosure in wing D. Until a few months ago, lemurs cohabited with Pedro, a very old mongoose lemur who loved kiwis, until he died.
Wild lemur populations are usually sympatric, meaning they live in the same geographical area. But scientists rarely see different species interacting with each other, according to Dr. Tecot. A 2006 study found that crowned lemurs and Sanford lemurs in Madagascar formed a multispecific association, communicating and coordinating their activities over time. Pairing between lemurs of different species seems even rarer, if at all. Dr. Tecot, who co-directs the Ranomafana Red-Bellied Lemur Project in Madagascar, has never seen any pair of mixed species in the wild.
In captivity, these pairs can offer insights into how lemurs can form companies between species, according to Ipek Kulahci, a postdoctoral researcher at the University of Notre Dame.
Cheyenne and Chloris, who will turn 33 in April, no longer have the energy to play. But they still sunbathe in their outdoor pen and warm up in their sleeping baskets, which are padded with wool blankets to cushion their old bones.
In recent years, Chloris has had more episodes of forgetfulness, in which she seems not to know where she is – her parents call them “important moments,” said Keith. But when Chloris returns to lucidity, in her good eye, she sees that she is still with Cheyenne.