Wader recruitment indices suggest nesting success is temperature-dependent in Dunlin Calidris alpina

Measures of annual breeding success are an important component of species monitoring programmes. It has been suggested that effective monitoring of breeding productivity for arctic breeding waders may be achieved from an analysis of annual variation in the proportion of juveniles in winter flocks. Here, we attempt to generate a recruitment index for Dunlin Calidris alpina caught during the winter in north Wales. This index revealed significant annual variation and we show that this is strongly correlated with summer temperature (but not rainfall) on the breeding grounds. Years with high recruitment were also correlated with increases in the national winter population estimate. In years of intermediate summer temperature, the recruitment index was highest and we discuss the possible implications this has for Dunlin under scenarios of future climate change. We were unable to generate a significant index for Common Redshank Tringa totanus and discuss possible reasons for this.