Testosterone Is Thought to Affect the Parenting Behavior of Male

Testosterone is thought to affect the parenting behavior of male birds.In an experiment using dark-eyed juncos, nest defense behaviors of males with experimentally elevated testosterone were compared with a control group with "normal" levels of testosterone.The theory predicts that elevated levels of testosterone will result in a decrease of nest defense behavior.When nests were presented with artificial predators, the number of swoops per minute was measured. (Swooping at a predator is a common nest defense behavior.)For each group of males, the distribution of swoops per minute was approximately normal.The following table summarizes the experimental results: