Influence of game restocking on the migratory behaviour of the common quail, Coturnix coturnix

Abstract

Background: The common quail, Coturnix coturnix, is a migratory bird hunted extensively across Europe. To satisfy this hunting interest, thousands of farm-reared birds are restocked every year. However, restocked individuals are not common quail but hybrids with domestic Japanese quail, C. japonica. Interbreeding between restocked and native birds in the wild allows the entry of alien alleles to the native populations, which could lead to the loss of adaptive phenotypes and behaviours, such as migratory drive. Sedentary individuals may face wintering conditions to which they are not adapted, suffering higher mortality. Some individuals have been observed to remain in northern latitudes during winter. Question: Does game restocking contribute to the sedentarization of the common quail population? Method: We sampled 42 quail during the autumn migration and 50 quail during winter in Spain. We genetically analysed them using a set of autosomal microsatellites and also sequenced a fragment of the mitochondrial DNA control region. We evaluated the proportion of admixed quail found and compared it with that previously found in a breeding population. Results: None of the migratory quail were admixed individuals, although two of them showed introgression of Japanese mitochondrial DNA. Among wintering quail, only three individuals had a genetic composition compatible with a farm origin, while the rest were common quail. Thus, the proportion of admixed quail during winter was not higher than during the breeding season. Conclusion: Restocking individuals with domestic Japanese quail ancestry is not directly associated with the presence of quail during winter in northern latitudes. The almost complete absence of individuals of farm origin among the migratory and wintering quail populations indicates that the vast majority of the restocked individuals probably die soon after release. However, the genetic composition of the breeding population has already shown that some survive until the next breeding season and introgress their genes into the wild population.