Effects of climate change on the degree of protandry in migratory songbirds

摘要: Current climate change is affecting the timing of life-history events birds, such as spring arrival at breeding grounds. Interspecific differences in advancement migration have hitherto been attributed to exposure climatic variables win- ter or on migration, without a more detailed consideration sex-specific and extent migration. Since males females migrate during different times season may segregate into wintering grounds, we expect differentially affect females. Furthermore, sexual selection theory predicts that degree protandry (i.e. time difference between male female arrival) should increase when forces natural opposing early relax earliest benefit from improved mating opportunities. Here, explore whether has changed period warming using long-term phenological data collected 5 North European bird observato- ries. We show for 4 sexually dichromatic songbird species generally advanced, but not changed. Moreover, provide evidence variation large-scale weather conditions, reflected Atlantic Oscillation (NAO) index, affected protandry. hypothesize parallel shift be due similar phenotypic plastic responses changes reflect correlated response In addition, discuss possibility observed could result seasonal shifts local environmental conditions under which birds both sexes 'fall out' are sampled.