Effects of weather conditions on the reproductive succes of House Sparrows

Abstract

The effects of climatic changes on various behaviors of animals have been documented, but there is still little information about how theweather variability and extreme meteorological events influence reproductive success in birds. In this study I have investigated the relationship between the ambient weather variability and the reproductive success of House Sparrows. Thestudied population breeds in a nest-box colony in the Zoo Veszprém. We monitored the breeding attempts from 2005 to 2010. Nestlings’ sex was identified by molecular sexing methods in a subset of broods. My results show that dry, warm weather is favourable during the incubation period, and promote fledging and nestling development after hatching, too. Fledging success increased with the frequency of warm days and decreased when temperature drops were frequent. Nestlings’ body size was smaller in wetter weather.There were more male nestlings under less variable, warmer and less dry weather conditions. Nestlings’ sex ratio did not differ from 1:1 in the study population. Damp warm weather may be disadvantageous for hatching success as it can favour microbial infections through the eggshell. Cold andwet weather may negatively affect nestling development and survival directly through the thermoregulation of nestlings and/or indirectly by decreasing food availability or parental provisioning rate. Male and female nestlings might be differentially sensitive to weather conditions. Weather probably has complex effects on the reproductive success of House Sparrows. It is worth to examine the deeper mechanisms of the effects of weather on different levels of avian reproductive biology.

The effects of climatic changes on various behaviors of animals have been documented, but there is still little information about how theweather variability and extreme meteorological events influence reproductive success in birds. In this study I have investigated the relationship between the ambient weather variability and the reproductive success of House Sparrows. Thestudied population breeds in a nest-box colony in the Zoo Veszprém. We monitored the breeding attempts from 2005 to 2010. Nestlings’ sex was identified by molecular sexing methods in a subset of broods. My results show that dry, warm weather is favourable during the incubation period, and promote fledging and nestling development after hatching, too. Fledging success increased with the frequency of warm days and decreased when temperature drops were frequent. Nestlings’ body size was smaller in wetter weather.There were more male nestlings under less variable, warmer and less dry weather conditions. Nestlings’ sex ratio did not differ from 1:1 in the study population. Damp warm weather may be disadvantageous for hatching success as it can favour microbial infections through the eggshell. Cold andwet weather may negatively affect nestling development and survival directly through the thermoregulation of nestlings and/or indirectly by decreasing food availability or parental provisioning rate. Male and female nestlings might be differentially sensitive to weather conditions. Weather probably has complex effects on the reproductive success of House Sparrows. It is worth to examine the deeper mechanisms of the effects of weather on different levels of avian reproductive biology.