Factors influencing mobility and survival of Eurasian Woodcock wintering in Spain

Survival and mobility have important implications for population management for game species. These parameters are influenced by both intrinsic and extrinsic factors. We describe movements (commuting flights between diurnal refuges and nocturnal feeding places; and escape flights during cold spells) and winter survival rate of Eurasian Woodcock (Scolopax rusticola) wintering in Spain. We also evaluate factors influencing these variables, using 51 radio-tracked birds over three winters (2008/2009, 2009/2010, and 2010/2011). Commuting flight distances were estimated at 961.5 +/- 1041.9 m, and variations were mainly explained by age and temperature (they decreased with lower temperatures and were lower for first-winter birds). Three cold spells occurred in 2009/2010; 80% of woodcocks monitored that winter showed escape flights, moving > 20 km, and went back to their previous wintering place when the effects of cold spells finished (about 8 days later). Of monitored woodcocks, 54.9% survived the winter. The most frequent cause of death was hunting, affecting mainly first-winter birds. Woodcock survival was lower in areas with more hunting days per week, and in Mediterranean than in Atlantic climate regions. Our results highlight the importance of monitoring survival and factors affecting it. Also, these results underline the importance of developing future studies to understand the importance of Mediterranean regions, the use of refuge places during cold spells, and hunting pressure there.