4 May 2002: Richard Harris, of National Public Radio, 'reported on a study published in this week's issue of Science that documents the behaviour of Chickadees. Researchers say female Chickadees eavesdrop on their mates' song contests — choosing to copulate with the winners, even if it is done on the sly.'

Chickadees, genus Parus, have a social hierarchy with the alpha males at the top who get the best food and the best mates. Social rank is determined by outcome of song contests, especially in spring when the sweet whistle is prevalent. Dominant males are ousted by the matching and overlapping song of a contender. Male songs are overheard by females; if a female's mate loses a contest then she is likely to copulate with the winner, cuckolding her mate who helps rear the offspring.

Question

A Chickadee's song changes with the time of year. This research may explain why — competition for mates. A question arises from this: Why would better singing ability indicate a fitter mate?

Speculative Answers

1. 
   Given that Chickadees live in a social hierarchy, mating with a better songster should improve the offsping's chance of attaining a high position with better access to food and potential mates.
   

2. 
   In context of X-Rated Brains¹, better singing ability is an indication of mental agility and wittiness in Chickadees, an attractive feature to swooning females. Chickadees, however, are unlikely to evolve into a world-dominant species because they are limited by the size of their braincase, which is hardly big enough to hold a small pea.
   

Conclusion

This said, Chickadees are one of the most cheerful creatures imbued with a zest for life. In the coldest weather while other birds are hunkered down wherever they can find shelter, Chickadees flit about after seeds or just turn somersaults in the air for sheer joy.