The reintroduction of grey and red-legged partridges (Perdix perdix and Alectoris rufa) in central Italy:: a metapopulation approach

The grey partridge became extinct in the province of Siena (central Italy) in the late seventies, whereas the red-legged partridge had already disappeared by the beginning of the twentieth century. Some reintroduction attempts of both species carried out in the 1980s gave encouraging but not definitive results, and failed after an initial success. This was probably due to the low number of birds released, the small size of the re-introduction areas, their isolation, the farm-bred origin of the partridges, and hunting. In the province of Siena, for the first time in Italy, a large-scale reintroduction program of grey and red-legged partridges was experimented. The project started up in 1995 with seven reintroduction areas for grey and four for red-legged partridge, and was extended to 19 areas (22,562 ha) for grey and 7 (6858 ha) for red-legged partridge in 2002. Population viability analyses for both species showed that if reintroduced populations were isolated they would be extinct in a few years. Therefore, a metapopulation approach was adopted (contemporary releases in reintroduction areas close to each other). In each area, 100-1000 partridges per year were released for a minimum of 3 years, from different farms in order to achieve the maximum initial genetic diversity. Releases were effected in late summer (August-September) in acclimatization pens containing 10-20 aviaries. The reintroduced population showed marked variability of some demographic parameters, such as pair density and brood production rate; instead, average brood size was relatively constant across the study areas, but with annual variations. Reintroduction success was limited to a few areas only, mainly depending on the habitat characteristics of the areas, their surface area and isolation, and on the degree of care for the birds during the acclimatization period.