Birdsong that is softer and less well defined than the usual territorial song, sometimes heard only at close quarters as a quiet warbling.
- ‘In the laboratory, hand-reared birds perform subsong throughout their first autumn and winter.’
- ‘That is, does the bird amplify and modulate the amplitude of subsong primitives, or shorten and protract them, or reorder them, etc.?’
- ‘Every time the bird compares its own subsong to the memorized template, the syllables most similar to those present in the template become slightly more probable.’
- ‘A bird uttering subsong is usually perched low and in an inconspicuous place; the beak may be closed while singing. Subsong is not confined in out-of-season utterances and may readily be heard during the period of full song.’