Mule Deer aren't very vocal. The times they are the most vocal is when they are fawns and trying to reproduce. Fawns tend to ball when injured and also bleat when they can't see their mom. Bucks in the breeding season grunt when they are chasing a doe in heat. This grunt can consist of one every minute or even three in a series of 15-20 seconds. The Lungs bring oxygen in and out of the body.