Robin Song: Why and How?
Answers by Dr. David Aborn

Q. What causes robins to sing in the spring?

Robin Song

Singing, like many other behaviors (including migration) is governed primarily by changing day length (photoperiod, or amount of daylight).

As days get longer, a bird's physiology changes, especially hormone levels. Hormone levels stimulate appropriate changes in physiology and behavior to prepare the bird for breeding. If you captured a robin in December and placed it into a room and turned the lights on earlier and earlier each day, you would stimulate the robin to enter breeding condition.

While spring's increasing day length is the primary factor, temperature and food supply can also moderate things. For example, if food is plentiful, this may stimulate birds to enter breeding condition a little earlier.
Dr. David Aborn, ornithologist
Dr. David Aborn

Q. How do baby birds learn their songs?

A. During the Critical Period, a young robin hears the song of its parents while in the nest and imprints on it. Then there is an 8-month Silent Period. This is followed by a Subsong Period, where the young robin starts emitting sounds. At first they are unstructured notes and, in a few weeks, the sounds become more like the species-specific song. With continued practice, the song becomes more crystallized, and eventually perfected.