Once a predator spots a prey animal, fear usually motivates the potential dinner to skedaddle. If the prey creature can run, swim, hop or fly away fast enough, for long enough, it has a chance of escaping.
Many animals won't flee an approaching predator until the intruder gets within a critical distance, called the flight distance. This distance changes between species and even for each animal, depending on present circumstances. Sometimes researchers use measures of this distance to estimate how much "fear" animals are experiencing at any point in time.
Getting away wastes time and energy that could otherwise be spent on important activities, such as eating or foraging for food, drinking water or protecting mates. But if a predator is within striking distance, the most important thing will be for the prey animal to save its hide.
Flight distance depends on several factors:
- The distance of the prey animal from a safe haven, such as its burrow, a tree or a lake.
- The importance of the activity the prey animal is engaged in.
- How fast the predator is approaching.
- The size of the predator.
- The prey animal's fitness and ability to get away.
In general, the more threatened a prey animal feels, the longer its flight distance will be. In other words, if an animals has reason to feel fearful, it probably won't let a predator get anywhere near it.
Although it can be very difficult to measure how fast animals run, swim or fly when chasing or being chased, here are some estimates of top speeds for a variety of species.
- Cheetah — 70 mph
- Homing pigeon — 95 mph
- Hummingbird — 60 mph
- Coyote — 40 mph
- Grizzly bear — 35 mph
- Black mamba snake — 15 mph
- Thomson's gazelle — 50 mph
- Ostrich — 40 mph
- Elephant — 25 mph
- Squirrel — 12 mph
- Killer whale — 35 mph
- Rabbit — 35 mph
Many of these animals cannot sustain such speeds very long. However, sometimes prey animals can surpass their typical top speeds when trying to escape a predator. After all, at that point, they're running for their lives!