Pleased to meet you
fosamax mg Avian hearing ability varies according to the season. So do other features. In winter, the testes of the cock sparrow dwindle to the size of a pinhead; with the nesting season, they swell to the volume of a baked bean. The ability to sing tends to surge with the urge to nest. A hormonal response that varies with daylight length also does strange things to the brain: the ability to acquire and deliver song dwindles, and the relevant area of the bird brain shrinks, in the winter. This is, says Tim Birkhead in Bird Sense, "a sensible energy-saving tactic" because brains are a big expense: the human brain for instance uses 10 times as much energy as any other organ.