Although male songbirds typically sing during the spring, when mating season begins, in order to attracts females, a new study by researchers from the University of Cambridge claims that the reason that they continue to sing during the wintertime is to improve their song quality in preparation for mating season, according to a press release.
In order to come to their conclusion, the team examined three hypotheses on wintering great reed warblers -'Acrocephalus arundinaceus' - that singing during the winter is conducted to defend their feeding area during the winter, that high testosterone levels during breeding season linger into the winter and stimulate singing, and that it is to improve the quality of their songs.
The study utilized data from a field study on great reed warblers in Zambia and compared it to all songbird species that breed in the Palearctic and migrate to sub-Saharan Africa. The results support the third hypothesis, singing to practice for breeding season; furthermore, when examining species with the strongest sexual selection for song quality, they found that male birds sang the most intensely in Africa, supporting the song improvement hypothesis.
The results shed light on the effects of the annual weather cycle on sexual selection in songbirds, although not everyone is convinced - Erich Jarvis from Duke University believes that winter singing may not be used for practice.
"They would need to show that an individual bird's song changes or stabilizes the more they practice during the winter," he said.
The findings were published in the Jan. 26 issue of The American Naturalist.
