Courtship

In 1973, Niko Tinbergen won a Nobel Prize for his work on animal behavior. One of the topics he studied was courting in stickleback, small freshwater fish. At breeding time, the male stickleback changes color from dull brown, to black and blue above and red underneath. At this time, he builds a tunnel-shaped nest of sand. Females swollen with unfertilized eggs cruise in schools through the male territory. The male performs his zigzag courtship dance toward and away from the female fish. Attracted to the red color on the male's belly, a female ready to lay eggs displays her swollen abdomen. The male leads her to the nest. He pokes the base of her tail with his snout, and the female lays her eggs and then swims away. The male enters the nest and fertilizes the eggs. In this manner, he may lead three or four females to his nest to lay eggs. Tinbergen showed in his studies that seeing the color red caused increased aggressiveness in males and attraction in females.