Individual traits and extrinsic factors influence survival of the threatened pin-tailed sandgrouse (Pterocles alchata) in Europe

Abstract

Survival and the underlying causes of mortality are key demographic parameters for understanding animal population dynamics and identifying conservation needs. Here we use a large data set of tagged wild pin-tailed sandgrouse (. Pterocles alchata) to examine the influence of individual traits (age, sex, size, movements and reproduction), and of temporal and spatial variations on the survival of this steppe-bird of conservation concern in Europe. Annual survival for adults and juveniles was estimated at 0.60 and 0.61, respectively. Survival rate tended to be lower towards the northern margin of the European distribution. In the core distribution area (central Spain) mortality was more frequent during the non-breeding season due to higher predation rates. Survival rate was slightly higher in males than females, which may explain male skewed population sex-ratios. Sedentary birds had lower survival than birds using different areas for breeding and wintering, indicating that high mobility, as a possible behavioural response to varying conditions, could eventually increase fitness. Predation was the main cause of mortality, but illegal hunting was also recorded, indicating a need for stricter law enforcement and regulation plans. Sandgrouse can be characterized by a relatively slow life history (medium-high adult survival and low reproductive rate), with lower survival rates than other sympatric steppe birds of larger size. Management and conservation efforts should focus on maintaining a high adult survival within protected areas. Sandgrouse mobility, which positively influenced survival, should also be taken into account in conservation plans, especially when considering the size and connectivity of protected areas.