I have a lot of ambivalence about animals in cages or pens. It’s born of childhood visits to Como Park Zoo in St. Paul, Minnesota, and seeing the pacing cats behind bars in small cages. Fortunately, those cages are long gone now, and zoological parks have generally been upgraded and are more “humane” (ahem). Someone once declared they would keep no creature with them that did not stay of its own free choice (Joseph Wood Krutch? Konrad Lorenz?) and amen to that.
On the other hand, when one considers the effects of poaching — and whatever else one can say about the gorilla in this picture, he has all of his parts still attached, as his creator intended: