The Southern grasshopper rat, also known as the “ghost wolf”, is a predator that often howls like a small wolf on a full moon night before hunting its prey. Found in the southwestern United States and northwestern Mexico, these rats specialize in eating scorpions, insects, other rats, and some plants. They are known to be extremely aggressive, attacking anything that moves that is not much larger than themselves. Grasshopper rats will even resort to cannibalism when food is scarce, ambushing their prey and killing them with a bite to the head. One of their favorite prey is the Arizona bark scorpion, known for its deadly venom.
To resist scorpion venom, grasshopper mice have developed a strategy to reduce the impact of the venom by pausing the pain signal transmission to the brain. This allows them to essentially not feel pain, although scientists are still unsure why the venom doesn’t kill them. Grasshopper rats also have the ability to bite off scorpion tails to prevent venom injection. When howling on a full moon night, these mice stand on their hind legs, raise their noses to the sky, and emit a call that can be heard from up to 100 meters away.
This howl helps them mark their territory and communicate with other rats. Grasshopper rats are highly territorial and mostly live alone, although some may form pairs of males and females. However, they are known to often kill their mates. These rats have a bell-shaped sound path that helps increase the sound intensity of their calls. Their howling is produced in a manner similar to humans speaking and wolves howling, using tissue vibrations produced by air currents.