A yellow diamond sign with the silhouette of a deer means:

A deer silhouette on a yellow diamond warns of an area where deer or other large wildlife are likely to cross the road. Animal-vehicle collisions are a leading cause of rural road crashes; deer collisions are common at dawn and dusk, in fall during breeding season, and along forested roads. Slow down in deer crossing areas, use high beams at night when no oncoming traffic is present, and scan the road edges. If a deer steps in front of you, do not swerve — many fatalities result from drivers veering into oncoming traffic or off the road to avoid an animal. Brake firmly and hit the animal if necessary; the deer is far less dangerous than a head-on collision or a rollover.