Use 'arboreal' to describe animals that primarily live, move, or feed in trees. Monkeys have an arboreal existence, skillfully navigating the treetops.
Pro Tip 2/3
Not Ground-Dwelling
'Arboreal' suggests the subject seldom comes to the ground, differentiating from terrestrial organisms. Squirrels are predominately arboreal, unlike rabbits.
Pro Tip 3/3
Home up High
Highlight the way 'arboreal' animals make their home in tree branches or hollows. Many birds are arboreal, building nests high above the ground.