Density of Grey Partridge (Perdix perdix Linnaeus, 1785) Population in Sakar Mountain (SE Bulgaria) and the Effect of Weather and Habitats

The breeding density of the Grey Partridge in Sakar Mountain is 1.23±0.19 (1-1.53) breeding pairs/km2. The brood size is 11.9±3.87 (3-21) ind./successful breeding pair. The breeding density of the grey partridges in the study area has been marked by peaks over several years, which are preceded by an increase in the average brood size. The reproductive success is 2.97 young per adult bird. There is a significant positive correlation between the brood size and the number of days with rainfall in July. There is a significant moderate positive correlation between the brood size and the area of the sunflower crops.