Tinbergen's Observations of Sticklebacks

In 1951 Niko Tinbergen wrote The Study of Instinct, a book filled with entertaining examples of animal behavior. A year later Tinbergen published an influential article in Scientific American, "The Curious Behavior of the Stickleback" (Tinbergen, 1952).

For many American psychologists, this was their first exposure to the concepts of ethology. Tinbergen explained how he came to devote years of study to a little fish.

When I was a young lecturer in zoology at the University of Leyden 20 years ago [the early 1930s] I was asked to organize a laboratory course in animal behavior for undergraduates.

In my quest for animals that could be used for such a purpose, I remem­bered the sticklebacks I had been accustomed as a boy to catch in the ditches near my home and to raise in a backyard aquarium.

It seemed that they might be ideal laboratory animals. They could be hauled in numbers out of almost every ditch; they were tame and hardy and small enough to thrive in a tank no larger than a hatbox. (Tinbergen, 1952)

Why were the sticklebacks handy lab animals?

Tinbergen performed high-quality re­search simply by observing the Stickle­backs' behavior in great detail and experimenting to see what changed their behavior. For example, Tinbergen observed the sticklebacks perform an elaborate mating ritual, carried out the same way each time.

First the male stakes out a little area of sand on the bottom of the ditch (or pond, or aquarium). This becomes his territory, defended against all other males. The male stickleback then digs a little hole, shoveling sand with his snout until the hole is about two inches deep and two inches wide.

He gathers stringy pieces of algae, coats them with a sticky substance secreted from his kidneys, and piles the algae in the pit, forming a little mound. Finally, the male stickleback wiggles through the mount, leaving a tunnel.

Now the stickleback changes color. He becomes bluish white on the back and bright red on the underside.

What is the stickleback mating ritual?

"In this colorful, conspicuous dress the male at once begins to court females." The females, in the meantime, have become fat with hundreds of eggs.

When the male sights a female, he darts toward her then veers toward the nest. She follows in a distinctive head-up posture. The male leads her up to the nest and thrusts his snout into the tunnel.

The female then slides into the nest, her head sticking out one end, her tail out the other. The male prods near the base of her tail with his snout, and this causes her to lay eggs in the nest.

When she swims out, the male swims into the nest and fertilizes the eggs. He repeats this ritual with several females.

As his mating urge wears off, the male's colors gradually fade. He takes up a sentry position near the nest, fanning the eggs with his fins in order to keep them supplied with oxygen.

As the eggs mature, they need more oxygen and the male spends more time fanning them. Finally the babies hatch and the male rounds up strays by catching them in his mouth and carrying them back to the area of the nest. When the babies are large enough, they wander off.

How were Tinbergen's observations of the Stickleback typical of early ethology?

This article by Tinbergen typified the ethological approach of the mid-20th Century. He worked with a species he knew and loved.

He centered his observations on instinc­tive behavior linked to the reproductive cycle. He was at home in the laboratory and also out in natural settings. Tinber­gen used sticklebacks in laboratory research, while his experi­ments with gulls were conducted in the wild.