Successful application of stable-hydrogen isotope measurements (deltaDf) of feathers to track origins of migratory birds and other wildlife requires a fundamental understanding of the correlation between deltaDf and deuterium patterns in rainfall (deltaDp) over continental scales. A strong correlation between deltaDp and deltaDf has been confirmed for birds and insects in North America, but not yet for other continents. Here, we compare deltaDf data from resident European birds to new deltaDp basemaps for Europe. Three maps, representing growing-season and mean annual deltaDp estimates from an elevation-explicit, detrended interpolation model and growing-season deltaDp estimates from simple Kriging, all indicate that strong isotope gradients occur across Europe with a general depletion occurring in a northeast direction. The feather data, representing 141 individuals of 25 avian species from 38 sites, ranged from -131 to -38 per thousand. Regression analysis showed that strong correlations existed between both mean annual and growing-season deltaDp estimated by detrended interpolation and deltaDf of non-aquatic and non-corvid birds (r2=0.66 and 0.65, respectively). We also examined mean annual and growing-season delta18Op vs. delta18Of for our samples. Both oxygen regressions were similar (r2=0.56 and 0.57, respectively) but poorer than for deuterium. Our study reveals that deltaD measurements of feathers from migratory birds in Europe may be used to track their origin and movements, and so provide a powerful investigative tool for avian migration research in Europe.

The Eurasian woodcock Scolopax rusticola is an important quarry species hunt ed all over its range. Some authors have reported local declines in both winter ing and breeding woodcock numbers. In order to investigate whether these pos sible declines are the result of a negative trend in survival, we analysed 3,312 recoveries of 15,839 woodcocks ringed in France during 14 consecutive win ters (1984/85-1997/98). We distinguished between winter (October& n d a s h ; February) and summer (March& n d a s h ; September) recoveries in order to estimate survival and recovery rate separately for each period because selective pressures during these two periods are likely to be different. Survival varied according to year dur ing both winter and summer. Winter survival probability covaried positively with mean winter nocturnal temperature and ranged from 0.74 (SE = 0.057) during the winter of 1985/86 to 0.83 (SE = 0.042) during the winter of 1994/95. Mortality of first-year birds was 22% higher than that of adults in any year. Results from a second analysis in which we compared survival of birds ringed during 1991-1997 in the three main woodcock wintering areas along the French Atlantic coast suggested a threshold effect of weather conditions. Mean win ter survival covaried with temperature and rainfall mainly in the northernmost regions where weather conditions are more severe. We did not find any par ticular trend in survival probability that could explain the possible declines in woodcock numbers. However, the generally low adult annual survival, and the negative influence of stochastic events such as severe winter conditions might drive populations to a level from which it would be difficult to recover. Results of a two-age-class demographic model are discussed together with implications for management.

In France, illegal hunting of the endangered ortolan bunting Emberiza hortulana has been defended for the sake of tradition and gastronomy. Hunters argued that ortolan buntings trapped in southwest France originate from large and stable populations across the whole of Europe. Yet, the European Commission referred France to the Court of Justice of the European Union (EU) in December 2016 for infringements to legislation (IP/16/4213). To better assess the impact of hunting in France, we combined Pan-European data from archival light loggers, stable isotopes, and genetics to determine the migration strategy of the species across continents. Ortolan buntings migrating through France come from northern and western populations, which are small, fragmented and declining. Population viability modeling further revealed that harvesting in southwest France is far from sustainable and increases extinction risk. These results provide the sufficient scientific evidence for justifying the ban on ortolan harvesting in France.

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