Effects of breeding date and weather on nestling development in White Storks Ciconia ciconia

Abstract

Capsule Chick growth rate was affected by air temperature and precipitation independent of the time of breeding. Aim To investigate how the time of breeding, sibling competition and weather conditions influence White Stork nestlings’ growth rate. Methods Chick development was determined by data on the length of bill, tarsus, wing, primary flight-feathers and body mass. Data were gained from 446 inspections of 50 nests during five breeding seasons at a site in Western Poland. Results The growth rate of chicks was different in particular years of the study and was affected by air temperature and precipitation. There was no effect of sibling competition, hatching asynchrony and time of breeding on chick development. Conclusions Birds that start breeding later have fewer offspring. However, chicks from early and later nests grow at the same rate. This similarity of growth rate is important because storks leave for wintering grounds in flocks which means that the development of chicks in the population has to be synchronized.