Age-specific decline in take-off flight performance in a small passerine

Abstract

Age-specific differences in individual performance are reported in a number of taxa and are particularly well documented in humans. However, such data are generally lacking for birds, the taxon showing exceptionally long life in relation to body size. Here, we studied differences in vertical flight performance among three distinctive age classes (0.5-, 2- and 4.5-year-old birds) in laboratory-kept zebra finches, Taeniopygia guttata . We found that take-off flight speed differed significantly between the age classes with the oldest birds being ca. 10% slower than the youngest birds. Age classes also differed significantly in flight motivation, with old birds tending to be less motivated to fly than young ones. Thus, the age-specific decline in flight performance is clearly visible in zebra finches. In a broader perspective, poorer flight performance may impair foraging efficiency, social interactions and, most importantly, take-off speed when escaping predators. This may help elucidate age-specific decline in reproductive and survival rates commonly observed in natural populations.