The pattern of song activity during different stages of the breeding cycle was investigated in males of the lesser whitethroat Sylvia curruca. Males had a high song output during the prefertile period after which the song activity declined abruptly. This pattern is consistent with the song functioning in territory defence and mate attraction. Most males did not sing when their mate was fertile. It is suggested that this silence is a strategy by which the male tries to conceal the precise position of the fertile mate to avoid being cuckolded. The lesser whitethroat has two song forms': 'trill' and 'twitter'. The physical properties of these indicate that they are specialized for communication over different distances. The high amplitude trill may serve as a long-distance signal whereas the low amplitude twitter allows only short-range communication. The two song forms could also have evolved for intersexual and intersexual usage. The stereotyped trill song form was dominant relative to the twitter song form late in the breeding cycle, indicating that trill is used primarily in male-male communication. The variable twitter song form was dominant early in the breeding cycle when the males were attracting mates, indicating that twitter is used primarily in male-female communication.
Sylvia curruca, song activity, silent strategy, long- and short distance communication, intra- and intersexual song form