Variation in song rate during the breeding cycle of the rufous bush chat, cercotrichas galactotes

Abstract

This study is an attempt to elucidate the functions of song in the Rufous Bush Chat Cerco-trichas galactotes, mainly in relation to the temporal pattern of song production during the stages of the reproductive cycle. Territorial males sing at the highest rate during the period of territory establishment and pair formation, declining to a lower level during the fertile period of the mate and remaining at a low (but partially higher) level afterwards. This result, together with the observation of a constant high rate of song produced by a male which lost his mate, support the mate-acquisition and territory-establishment hypotheses on the functions of song, and suggests that the decrease during the fertile period of the mate may represent an attempt by the males to hide the fertility status of their mates from potential male competitors. The partial increase in song rate during the neighbouring females' fertile periods suggests an EPCs seeking function. Males do not adjust their singing rate to avoid detection of nest during the time of potential brood parasitism by the Cuckoo Cuculus canorus, and they sing much less during the period of nest occupancy, in this way perhaps eluding nest detection by potential predators.