alone
animal
animals
ape
bars
behind
black
brown
cage
captive
captivity
chimpanzee
depression
despair
endangered
environment
expression
expressive
eye
eyes
face
fence
freedom
funny
hair
head
iron
jail
jungle
locked
loneliness
lonely
looking
mammal
metal
monkey
natural
nature
primate
prison
sad
sadness
small
solitude
thoughtful
trapped
wild
wildlife
zoo