December 22, 1956, was a historic day for the zoological world as we welcomed the first successful zoo gorilla birth - a female, eventually named Colo in honor of her birthplace, Columbus, Ohio. She quickly captured the hearts of thousands of individuals and even graced the cover of TIME Magazine. The world watched eagerly for news of Colo's development and growth and she has taught us a lot about gorilla behavior. Today, Colo's descendants can be found throughout the United States as ambassadors for their species. Nearly six decades later, Colo is still surprising the zoo community and teaching us about this remarkable species.

Like humans, gorillas in zoos are living longer and longer. In 2013, Colo celebrated her 57th birthday. Caring for Colo and other elderly gorillas presents a new set of challenges, and zookeepers, veterinarians and maintenance staff have had to become more creative with their care. The Columbus Zoo indoor gorilla habitat is comprised of several gunite trees that provide climbing opportunities as well as aiding the gorillas in utilizing the entire vertical space of the exhibit. All of our transfer doors are off the ground and the gorillas have to climb these trees to move from room to room. About 10 years ago we noticed that it was more difficult for Colo to navigate this area and that she was much more cautious in her movements. To help Colo move around, the staff added a firehose that runs the length of the tree in order to provide a railing she can hold onto. We also had our exhibitry department create realistic looking knots in the tree that act like steps and provide more traction. Finally we added two mesh ramps that make it easier for her to get onto and down from these trees. We no longer shift Colo around to all the rooms in this space, but with these modifications she has an area she can get around in safely.

Overall, Colo has been an extremely healthy gorilla. A few of the medical issues she has had include constipation, urinary tract infections, arthritis and loss of muscle tone. We started noticing a loss of body tone/weight when Colo was about 40 years old. At that time we supplemented her diet with protein powder and ensure. In more recent years we have adjusted her diet and started her on an exercise program and no longer feel the need for these supplements. Basic repetitions of lifting her arms and standing have helped her muscle tone. Additionally the staff give her the opportunity to move through the chutes in both of our areas. Having the choice to move between buildings to see all of our other gorillas not only mentally stimulates Colo, but also encourages her to move around more.

To help control her arthritis and keep her moving comfortably, the vets started her on monthly adequan injections. Keepers have seen a remarkable improvement in her movement since these were started in 2009. Colo's arthritis is most severe in her hands. In order to help her exercise her fingers and keep her joints moving, we had a student do a diet study for us in 2010. The point of the study was to see what presentation of diet was most beneficial to Colo, both in terms of making her use her fingers and getting her to eat all items offered. We found that the larger we left the food items, the more fingers she used to eat them and that she flexed these fingers more. Based on this study we no longer cut her food up small and scatter it around the room, a practice commonly employed to increase foraging time. Finally, the addition of cranberry juice and acidophilus capsules help with urinary tract health, and a daily dose of prunes keeps her bowel movements regular, something monitored daily by the staff.

The final thing that has changed for Colo over the years is her social grouping. Colo has served many roles in our gorilla community and has been integral in the education of countless younger animals but, in 2006, she let us know that she was ready to leave group dynamics behind and live by herself. Colo is always next to gorillas and she has visits with other animals, but she prefers to watch over the other groups and give sage advice from afar, and she particularly enjoys playing with her great grand-daughter through the mesh. Although living alone is not the right choice for all older animals, it was the choice that Colo made, and the keepers were ready to accommodate her wishes.

In 2012, Colo set a new longevity record for gorillas. Though her situation is not typical (median life expectancy is 37.5 years for a female), we have been blessed to have such a wonderful animal educating us on the species. From the time of her birth, Colo has brought happiness, understanding and hope to many generations of gorillas and the people who love them.

Audra Meinelt

Update: Colo celebrated her 60th birthday in 2016 and died a few weeks later.