Certainly birds do a lot more singing and chirping in the spring and summer than any other time of the year because it’s breeding time. But as the weather cools in the fall, many birds continue chirping away. Still looking for a mate? Hardly. Researchers have discovered a physiological foundation specifically linked to testosterone, that keeps our feathered friends out on limb chirping away the hours.

In the spring and summer months, a high testosterone concentration is typical in many species and is known to increase singing and may also result in displays of territorial aggression (passerine). These same high levels of testosterone result in full-fledged “songs” rather than bits and pieces of melody.

As the seasons change and begin to cool off, not all species of birds migrate. Those species that stay behind tend to defend the same territory they used earlier for breeding. For example, Song Sparrows establish and defend winter territories which are maintained and defended by small groups of two or three individual birds made up of males and females.

So that singing you’re hearing on a cool crisp autumn day? Just the bird letting everyone know it’s going to be around for a while.

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