Upland habitat use by Pyrenean grey partridges Perdix perdix hispaniensis during the breeding season

Whereas in most of Europe the decline of the grey partridge Perdix perdix is due primarily to agricultural intensification, the Pyrenean grey partridge P. p. hispaniensis is believed to suffer from the opposite effect, namely the abandonment of agricultural practices which allows the encroachment of dense shrublands. We investigated habitat use by the Pyrenean grey partridge during the breeding season and its relationship with reproductive success and survival. The study was based on 22 radio-tagged grey partridges in a 5,800-ha upland area of the eastern Pyrenees. Habitat use was non-random, and shrubland with a shrub canopy cover higher than 40% was the most important requirement during the breeding season. In the spring, pairs that successfully reared a brood used shrublands (20-60% cover) twice as frequently as unsuccessful breeders, then in the summer halved their use of open habitats (montane grassland and shrubland with <40% cover), whereas failed breeders increased it sevenfold. Consequently, a good mixture of different cover types in the spring and summer is likely to provide the most suitable breeding habitat. There was no evidence linking the spring/summer survival of adult partridges to a particular habitat use. Current grazing practices, especially with the use of controlled burning to clear shrubby vegetation, reduce the amount of mature shrublands used by Pyrenean grey partridges. However, grazing management also delays the natural vegetation succession and hence contributes to the long-term persistence of partridge habitat. Grazing practices that prevent reafforestation and maintain a mosaic of dense and open shrublands should be encouraged in the Pyrenean uplands.