Apparent constant adult survival of a Sand Martin Riparia riparia population in relation to climatic variables

The Sand Martin Riparia riparia is a trans-Saharan migrant species, whose populations are declining throughout Europe. We present the results of a multiple year study on a breeding population of Sand Martins along the River Po in Northern Italy through ringing breeding birds at nesting colonies (2002–2014). There was a trend for the abundance of the studied population to fluctuate. Recapture data were analysed to obtain apparent survival probabilities which differed between the sexes, but not between years. No apparent relationship was found between survival and three different meteo-climatic indices (North Atlantic Oscillation, Sahel rainfall and Lake Chad rainfall). During the 1980s and 1990s, winter survival was positively correlated with rainfall in the winter quarters. Although rainfall in the winter quarters has been more stable during the past 15 years, Sand Martin populations are still decreasing. Our findings suggest that the relationship with rainfall no longer holds, and that current population declines may be unrelated to climate in the winter quarters.