Chinchillas live in all the groups cause when they mate they go in a group and when they don't mate they ether live by themself's or in a group of the same gender.
Chinchillas are the prey of large birds, Wildcats, and snakes.
Their coat color helps them when they are hiding from prey. They stay in herds of same gender so they have smaller chance of getting eaten. Their big ears help them to hear their prey.