摘要 : Song in birds is traditionally associated with two major functions: mate attraction and territory establishment/defence. In some birds, these functions are divided between different types or categories of signals, while in others ... 展开 Song in birds is traditionally associated with two major functions: mate attraction and territory establishment/defence. In some birds, these functions are divided between different types or categories of signals, while in others the song repertoire is functionally interchangeable. Grasshopper Sparrows, Ammodramus savannarum, sing two distinct songs. Buzz song is prominent early in each breeding cycle, while warble song is typically more prominent later in the breeding cycle, and is only sung by paired males. To investigate the functions of these two song categories we did population-level song surveys, and performed a song playback experiment using buzz songs and warble songs as stimuli. Males singing buzz song responded to playbacks of both song categories almost exclusively with buzz song. Responses by birds singing warble or combined (buzz-warble) song were mixed, but these males responded to both song categories with buzz song at levels greater than chance. Our results suggest that buzz song is the principal category of song used for both the traditional intra- and inter-sexual functions associated with song. The function of the warble song class remains unclear. It may have predominantly inter-sexual functions such as social cohesion, reproductive synchrony within the pair, or extra-pair mate attraction. In a second playback experiment we examined song function further by testing the different components of buzz song. Results indicate that as in some other species, the initial segment of the Grasshopper Sparrow buzz song may act as an alerting component that enhances signal detection for long distance communication. 收起