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JoJo, a 32-year-old male silverback gorilla from Lincoln Park Zoo, is now part of breeding program at Brookfield Zoo.
The Chicago Zoological Society, which manages Brookfield Zoo, is happy to announce the addition of JoJo, a 32-year-old male silverback gorilla from Lincoln Park Zoo, as part of a breeding program for the critically endangered western lowland gorilla species. During the past month the gorilla exhibit has been closed to the public allowing JoJo to become acclimated to Brookfield’s female gorillas and his new home—Tropic World: Africa. The exhibit is now open to guests daily.

JoJo’s transfer to Brookfield Zoo is based on a recommendation from the Association of Zoos and Aquariums’ (AZA) Gorilla Species Survival Plan (SSP). An SSP is a cooperative population management and conservation program for select species in accredited AZA zoos and aquariums. Each SSP manages the breeding of a species to maintain a healthy and self-sustaining population that is both genetically diverse and demographically stable. “We are excited to have JoJo at Brookfield Zoo as he is an excellent genetic match for all three females currently in our care,” said Craig Demitros, associate curator of primates for the Chicago Zoological Society.


Initially, Animal Programs staff hope JoJo breeds with 24-year-old Binti Jua and 17-year-old Koola, who is Binti Jua’s daughter. When 8-year-old Kamba, Koola’s daughter, turns 10, she will also be allowed to reproduce with JoJo. Until then, she will remain on birth control. The SSP recommends that females be reproductively controlled until they are 10 years old.

According to the Gorilla SSP, JoJo is currently one of the most genetically valuable males in the zoo population. Records indicate that the oldest male gorilla to reproduce was 42 years old. Within the gorilla population, breeding normally occurs in three- to four-year intervals, so JoJo could potentially produce five to six offspring over the next 10 years.

“The addition of JoJo will have a positive impact on several levels, including the welfare of the individual gorillas involved and the continuation of the gorilla breeding program at Brookfield Zoo as well as the zoo gorilla population as a whole,” said Demitros. “Brookfield Zoo is committed to gorilla care and management and hopes to contribute to the overall conservation of this critically endangered species.”

JoJo Gorilla (right) at Brookfield Zoo with Kamba Gorilla (left)
Kamba Gorilla (left) checks out new arrival JoJo, a 32-year-old male silverback
western lowland gorilla from Lincoln Park Zoo.

JoJo will now become the gorilla group’s silverback, and Brookfield Zoo’s current 44-year-old male gorilla, Ramar, will enter “semiretirement.” Ramar is still on exhibit in Tropic World but is in a different habitat from the rest of the group. In the future, he will be exhibited with other primates for companionship.

Western lowland gorillas are endangered due to habitat destruction, primarily from illegal and legal logging, the effects of war and refugees in ape habitats, the illegal pet trade, and poaching for bushmeat. The recent demands for bushmeat by an increasing number of urban consumers have grown beyond sustainable levels. Great apes are disproportionately affected by this industry because these large-bodied animals are easy targets for hunters, and their slow reproductive cycles cannot sustain the current drain on their populations. It is not known how many western lowland gorillas survive in their native West Africa (the forests of Cameroon, Equatorial Guinea, Gabon, Nigeria, Congo, and Angola). Some recent estimates have been between 90,000 and 110,000 individuals, but new surveys are needed to determine whether or not this figure is exaggerated.