The great apes at The Detroit Zoo live in a 4-acre habitat that is home to two Western lowland gorillas, as well as chimpanzees and drill monkeys. The primates spend their days foraging, grooming and playing, just as they would in their native African environment, according to the zoo's website. Sometimes visitors can't even see the animals because the lush, large area gives them room for privacy when they need it.
"The challenge is for them to thrive," Kagan said. "So, if they're not thriving here, they should go live somewhere else."
He added that one thing is for sure when it comes to issues of animal captivity and conservation: "It's a constantly changing thing. There will be changes."
In the case of Harambe's death, Kagan said, in his view, a human - whether it was the child or the adult - "just made a mistake."
Update: In November, a federal inspection of the zoo found that the barrier (which has since been replaced) was not in compliance with standards for keeping primates in captivity when the boy managed to get in Harambe's habitat. The investigation is ongoing.