Migrating curlews on schedule: departure and arrival patterns of a long-distance migrant depend on time and breeding location rather than on wind conditions

Abstract Background Departure decisions in long-distance migratory bird species may depend on favourable weather conditions and beneficial resources at the destination location, overarched by genetic triggers. However, few studies have tried to validate significance of these three concepts simultaneously, long-term, high-resolution tagging datasets recording individual movements across consecutive years are scarce. We used such a dataset explore intraspecific intra-individual variabilities departure arrival from/to wintering grounds relation different migration. Methods equipped 23 curlews ( Numenius arquata ) Wadden Sea with Global Positioning System data loggers record their spatio-temporal patterns from site, first part spring obtained for 42 migrations over 6 years, 12 individuals performing repeat years. Day year was related 38 meteorological bird-related predictors using least absolute shrinkage selection operator (LASSO) identify drivers decisions. Results Curlews migrated almost exclusively Arctic sub-Arctic Russia breeding. They left site mainly during evening mid- late April returned between end June mid-July. There no difference times sexes. Weather parameters did not impact decisions; if days coincided headwind conditions, birds accounted this flying higher altitudes up several kilometres. breeding further away areas snowmelt departed later. Departures dates varied only < 4 tagged Conclusions These results suggest that trigger migration migrant is largely independent but subject resource availability areas. The high repeatability among subsequent lack relationship importance triggers prompting start Further insights into timing immatures closely might help unravel mechanisms triggering patterns.