The role of nest-site selection and cereal production in differential nest predation in Common Quail Coturnix coturnix and hybrid quail C. coturnix x C. japonica

In Europe, farm-reared quail used for restocking purposes are often hybrids between the Common Quail Coturnix coturnix and the Japanese Quail Coturnix japonica. These hybrids interbreed with wild Common Quail populations and suffer higher rates of nest predation, which would suggest that the two quail types have different nest-site selection patterns. We monitored 103 radiotagged nesting females (77 wild Common Quail over 18 breeding seasons and 26 hybrid quail over six breeding seasons) and analysed their nest placement behaviour. Our results did not provide any evidence that the quail types showed different nest-site selection trends, as they all preferred to nest near cereal field margins. The higher nest predation rate experienced by hybrids might therefore be explained by less effective anti-predator behaviour among hybrid females during incubation. As no edge effect on nest predation was observed, the preference for nesting close to cereal margins could be due to the greater food resources of field margins. Moreover, Common Quail nest predation decreased with a rise in barley straw production, supporting evidence that nest cover plays an important role in the prevention of nest predation in this species. No such relationship was found for hybrid quail, but this result is not conclusive, as the data on barley straw production for hybrid quail covered a much smaller range of interannual variability. Barley straw production in Catalonia decreased significantly between 1992 and 2012, possibly as a result of a change in the barley varieties used. This practice could entail a conservation threat for ground-nesting bird species.