Animal Behavior

Born with it: instinct

An innate behavior, or instinct, is one an animal is born able to do. It is inherited through genes, so it needs no teaching or practice, and every healthy member of the species does it in about the same way. Scientists call these behaviors “hard-wired.”

• A fixed action pattern is a set of actions that, once started, runs to the end. A male three-spined stickleback fish attacks other males, which have red bellies in breeding season. He will even attack a red-bottomed object that looks nothing like a fish.
• In a kinesis, an animal changes how fast or how much it moves, in no set direction. Woodlice, also called pill bugs, speed up when the ground is too hot or too cold, which raises their chance of reaching a better spot.
• In a taxis, an animal moves toward or away from something. The one-celled Tetrahymena swims toward certain chemicals, a behavior called chemotaxis.

Instincts help when there is no time to learn. A newborn animal that had to learn how to escape danger might not survive its first lesson.

Learned behavior

A learned behavior comes from experience. Learning is slower than instinct, but it is flexible: an animal can change what it does when its surroundings change.

The simplest kind is habituation, when an animal stops responding to something that happens again and again without harm. Prairie dogs give an alarm call when a predator comes near. They can learn to ignore the sound of human footsteps when the footsteps never bring harm, yet they still call when they hear a predator.

Imprinting

Imprinting is a kind of learning that happens fast and only at a certain age, during a short critical period early in life. Newly hatched ducklings bond with the first adult they see, normally their mother, and follow her everywhere. Following her keeps them close to food, warmth, and safety.

The Austrian scientist Konrad Lorenz showed what happens when that first sight is not a duck. A newborn duckling imprints on the first moving object it sees in the critical period, whether that is its mother, a cardboard box, or a balloon, and follows it as if it were its mother. Imprinting needs a built-in readiness to learn, plus the right experience at the right time.

Conditioning

Conditioning is learning that links two things together.

In classical conditioning, an animal learns to connect a new signal with something it already reacts to. The Russian scientist Ivan Pavlov studied dogs, which drool naturally when they get food. Pavlov rang a bell each time the dogs were fed. After a while, the bell alone made the dogs drool, even with no food in sight.

In operant conditioning, an animal learns from what happens after it acts. The American scientist B. F. Skinner put rats in a box with a lever. When a rat pressed the lever, food dropped in. The rats soon pressed the lever again and again. People train pets the same way when they reward a dog for sitting.

Communication

Animals send each other signals. A signal can be chemical (a scent called a pheromone), a sound, something seen, such as a courtship display or a threat, or a touch. Some signals are instinctive, some are learned, and many are a bit of both.

The most famous signal is the honeybee’s dance, decoded by the Austrian scientist Karl von Frisch. A worker bee that finds food comes back to the hive and dances on the comb in the dark. When the food is close, about 50 meters or less, she does a round dance. When it is farther, she does a waggle dance: she runs in a straight line while waggling her body, loops back, and repeats.

• The direction of the straight run shows where the food is. Straight up on the comb stands for the direction of the sun, so a run tilted 40 degrees to the right of up means “fly 40 degrees to the right of the sun.”
• How strongly and how long the bee waggles tells the others how far away the food is.

Von Frisch found that bees do this dance without being taught, so it is an instinct.

Living in groups

Many animals live in groups. Behavior between animals can be sorted by who benefits:

• In selfish behavior, only the animal acting benefits.
• In altruistic behavior, one animal’s actions help another, sometimes at a cost to itself. Parents caring for their young are an example.
• In cooperative behavior, both animals benefit.

Social insects such as bees, ants, and termites show how far this can go. Most workers in a hive or colony never have young of their own. Instead they gather food, guard the nest, and care for the young of the queen, who is their close relative.

Some behaviors help animals find mates. Male sage grouse gather in a shared courting area called a lek and put on showy displays, and the females choose a mate from the group.

Migration

Migration is a long-distance, usually seasonal, move from one place to another and back. Many birds fly south for the winter, and salmon swim from the ocean back up rivers to lay their eggs. Animals migrate to follow food, warmth, or safe places to raise young.

• Arctic terns nest in the Arctic during the northern summer, then fly to the seas near Antarctica for the southern summer. In one tracking study of terns from Greenland and Iceland, the birds flew on average about 70,000 kilometers in a year, the longest yearly migration ever recorded for any animal when the study was published.
• Monarch butterflies from eastern North America fly to a few mountain forests in central Mexico each fall, a trip that can be more than 3,000 kilometers. They spend the winter there, then head north in spring. No single butterfly makes the whole round trip: it takes several generations to get back to the northern United States and Canada.

Key words

• Behaviorwhat an animal does in response to the world around it
• Instinctan innate behavior an animal is born able to do, without learning
• Learned behaviora behavior that comes from experience
• Habituationlearning to stop responding to something harmless that keeps happening
• Imprintingfast learning during a short critical period early in life
• Classical conditioninglearning to link a new signal with something an animal already reacts to
• Operant conditioninglearning from the reward or punishment that follows an action
• Pheromonea chemical signal that animals of the same species respond to
• Migrationa long-distance, usually seasonal, move from one place to another and back

Game: Which Kind of Behavior?

You will see twelve behaviors, one at a time. Decide what each one shows: instinct, imprinting, or conditioning. A behavior you sort on your first try earns 1 point, for a total of 12. Your best score is saved on this device.

Quick quiz

Six questions. Pick one answer for each, then press Check my answers.