Shoo Bully, Go Away… (Mobbing)

Photo Group
Red-Tailed Hawk
Photo by: 
Rick Jordahl

Ruth and I were doing one of our Breeding Bird Survey Routes last week and had the chance to watch two Eastern Kingbirds (see page 4) and a male Scissor-tailed Flycatcher “chasing” an adult Coopers Hawk. I use the term chasing lightly here because the hawk wasn’t really flying away from them, he was just passing through their territories and they wanted to make sure he didn’t stick around. The behavior is known as mobbing and it is pretty widespread in the bird world.

Why didn’t the deadly Cooper’s Hawk just snatch one of the kingbirds right out of the air? As a rule, smaller means quicker and more maneuverable. Birds of prey generally catch their victims by surprise. If a smaller bird can see the hawk coming, they are often able to use their quickness to get to cover. In the case of the kingbirds, they simply were keeping clear of the hawks head and talons as they pecked at her.

Why do birds mob other birds. The theory is that they are chasing a potential predator from their territory. Owls and hawks are frequent victims of crows, jays and others while crows and jays are often mobbed by kingbirds, mockingbirds and even smaller species. Other victims include Great Blue Herons, Turkey Vultures and Common Nighthawks. It plays out like a reverse pecking order.

The behavior is not limited to would be avian predators. Small birds will harass snakes, chipmunks and all types of animals that get close to their nests or young.

Does mobbing work? In short the answer is “no.” Repeated studies show that while the bird being harassed does leave that area while being pestered, it will return to the area later. It can be a great aid to birders. It has led me to an owl during daylight hours on many occasions.

If the behavior doesn’t work, why do birds waste their energy doing it? We really do not know for sure. One theory I did come across was that it may be an active teaching tool so that their young will readily recognize a dangerous animal.

For more about the “king” of mobbing, don’t miss the Species Profile and the next time you hear group of crows or jays in the woods going “crazy,” try to sneak up and see if it isn’t an owl.

By Mark McKellar

Summer 2006