Alarm Responses

Probably the best way to avoid being eaten by a predator is simply to stay out of its way. The slap of the beaver's tail, the flash of a white tail-patch of a deer, the "chip chip" of a bird, the "scolding" of a squirrel are all alarm responses. They warn of danger in the presence of a predator, allowing prey animals to flee.

What did researchers discover about alarm calls of vervet monkeys?

Vervet monkeys have at least three distinct alarm calls for three different predators: leopards, eagles and snakes. The alarm signals lead to distinct behavioral responses. When Seyfarth and colleagues (1980) played tape recordings of alarm calls to a group of free-ranging (non-captive) vervets, the leopard-type alarm call made the monkeys run into trees. The eagle-type alarm call made them look up at the sky. The snake-type alarm call made them look down to the ground.

This finding led to a flurry of research documenting variable and informative aspects of alarm calls in many species. For example, the little black-capped chickadee, a bird commonly found in American neighborhoods, varies its alarm call depending on the predator, and its alarm call is understood by other birds such as nuthatches.

When a chickadee sees a predator, it issues warning call-a soft ''seet'' for a flying hawk, owl or falcon, or a loud ''chick-a-dee-dee-dee'' for a perched predator.

The ''chick-a-dee'' call can have 10 to 15 ''dees'' at the end and varies in sound to encode information on the type of predator. ("Nuthatches Seem to Understand Chickadee," March 20, 2007)

What is the benefit of shared alarm responses, among different species?

Alarm responses are often shared by several species. This benefits every animal that participates in the shared alarm system (usually a group of prey animals). The result is an alarm system more sensitive than any one species could provide on its own. Watering holes on the African savanna are frequented by all sorts of prey animals, such as baboons, birds, and cattle. All are threatened by the area's chief predator: the lion. When a member of any prey species senses the approach of a lion, it makes an alarm call and all the animals of all the various prey species flee.

How do humans participate in shared alarm calls?

Humans participate in a variety of shared alarm calls. A watchdog shares its alarm call with its owner when it barks at shadowy objects in the night. Pet birds and cats also warn their owners of intruders or dangers, on occasion. Burden (1975) collected a "bulging file" of newspaper clippings about cat heroes.

Take a family in Lewiston, Idaho, whose mistress decided to take a nap in the middle of the day. About two hours later her pet cat Tiger roused her with loud and anxious mewing. Following Tiger into the spare bedroom, the lady found pieces of ceiling falling onto the floor in flames. She managed to rescue Tiger and her kittens, but it was only a matter of minutes before the whole house went up in flames.

Notice that the woman probably lost many valuables in her house, but she saved the cat and her kittens. This helps answer the question, "What's in it for the cat?"

What is the human alarm response?

The human alarm call is the scream. It emerges in stereotyped form, without learning, in normal members of our species. Small children commonly scream as an involuntary response to certain stimulus situations, such as being approached by an adult playing the role of a monster. Like other species' alarm responses, a scream can be detected at a large distance, providing a useful warning.


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Copyright © 2007 Russ Dewey