Spatial movements of grey partridge Perdix perdix : male-biased spring dispersal and effect of habitat quality

The Grey Partridge Perdix perdix is a sedentary species with a surplus of males in spring populations. It experienced a dramatic decline in Europe primarily due to habitat loss that may have forced the species to modify its dispersal behaviour, a less transparent source of populations threats. We analysed the dispersal patterns of Grey Partridges during pre- and post-breeding periods in two landscapes with different habitat quality in the Czech Republic. Grey Partridges tended to pair off quickly, with most pre-breeding movements executed in pairs. The birds usually dispersed over a few hundred metres indicating that the habitat conditions in a landscape with a carrying capacity of 2–5 pairs/1 km² was not below the threshold initiating strong dispersal, as observed in extreme habitats and at the northern limits of the species′ distribution range. A few single males that had remained unpaired until April also finally bred. However, the high level of sedentariness of males in a good landscape suggested that males prefer to stay near wintering sites unless habitat sources become limited. Unlike the males, the females dispersed in a wide range of distances with an extensive overlap in both landscapes. Autumn movements did not differ between the sexes, but were longer than the pre-breeding movements and increased in a poor landscape. We conclude that both reduced habitat availability and reduced mating opportunities initialise primarily male-biased breeding dispersal in Grey Partridge populations.