Impact of game restocking on common quail populations

Resumen

The common quail (Coturnix coturnix) is a popular game bird in Europe. The massive restocking of farm-reared individuals for hunting purposes is a common practice in several European countries. Although restocking of common quail is legally allowed, some suspicion has been aroused about the possible hybrid origin of farm-reared quails from crosses with domestic Japanese quail (C. japonica). Hybrids do not show the migratory instinct observed in common quails, which allows them to overcome the annual depletion of the habitat: winter cereal fields that are harvested. Because of that, crosses in the wild between farm-reared and common quails may result in the introgression of adaptive alleles in native populations, posing an important threat for the common quail. The goal of this thesis is to understand the effects that game restocking has over common quail populations, and to gain knowledge applicable to improve common quail conservation and management. By the use of genetic methods, results from this thesis show that the vast majority of quails reared in Spanish farms for restocking are not common quail but domestic Japanese quails and hybrids. In the wild, restocked individuals show higher mortality and nest predation than common quails, but they successfully reproduce with the same or even higher probability than native quails. Results show that genetic introgression has already occurred in common quail populations in Catalonia, and genetic data is compatible with a slow rate of ongoing introgression of domestic Japanese quail alleles into the common quail gene pool. Simulations predict this could result in extensive admixture in the near future if release practices are maintained. Intensive control and genetic monitoring of individuals for restocking is needed as the massive release of farm-reared hybrids represents a severe threat for the long term survival of the common quail.