Growth and Development of the Rufous-Winged Sparrow (Aimophila carpalis)

Abstract

The rapid growth and development of the rufous-winged sparrow are geared to its short nestling period (8-9 days) and are similar to those of other sparrows. In most aspects of development, this sparrow is considerably less mature at fledging than the cactus wren [Campylorhynchus brunneicapillus] which has a long nestling period (20 days). In the sparrow only those functions necessary for survival out of the nest reach the level of maturity of cactus wrens at fledging. A developmental stage comparable to that of a fledging cactus wren is attained by the sparrow during the 1st wk after fledging. The short nesting period of sparows probably is an adaptation to high mortality rates in the nest and is a key to their success in habitats affording brief nesting seasons.