Growth of nestling Grey-Crowned Babblers, with notes on determination of age in juveniles

Abstract

Parameters of a curve describing growth of nestling Grey-crowned Babblers Pomatostomus ternporalis were estimated by a new trial-and-error least-squares method with the aid of a computer from weights of fledgelings and nestlings. For a passerine of the temperate zone, growth rate and percentage of adult weight at fledging are unusually low and the nestling period is unusually long. These features are correlated with nest structure, mode of foraging, and perhaps with social organization. Criteria for determination of approximate age in juveniles were developed using banded wild birds. Criteria include colour and length of bill, colour of gape and characteristics of plumage.