Data from: Migration tendency delays distributional response to differential survival prospects along a flyway

When populations grow or decline, habitat selection may change due to local density-dependent processes, such as site dependence and interference. In seasonally migrating animals, nonbreeding distributions may be determined through these mechanisms of density dependence, which we examine here at a hemispheric scale for a long-distance migrating bird. Using summer and winter resightings of 2,095 Eurasian spoonbills Platalea leucorodia leucorodia that were ringed in the Netherlands during 16 years of fast population growth, we show that neither site dependence nor interference fully explains their patterns of survival and winter distribution. Within their three main wintering areas, annual survival decreased with an increase in population size. While survival was consistently higher in the two European wintering areas (France, Iberia), most spoonbills migrated onward to winter in west Africa. The number of birds wintering in Europe increased, but not enough to maximize annual survival. We conclude that a constraint of tradition (their "migration tendency") inhibits birds from changing their migratory habits. We pose that this phenomenon may similarly constrain other migratory populations from rapidly responding to large-scale climate- and/or human-driven habitat changes at their wintering grounds.Encounter histories adult spoonbills 1994-2010This datafile (plain textfile to be imported in program E-Surge) contains the encounter histories of 2095 adult (>3cy) Eurasian spoonbills, born between 1988 and 2007 and resighted between summer 1994 and summer 2010. Two resighting periods per year are defined (summer = March-September, winter = December-January for France and Iberia and October-February for Mauritania & Senegal). Events are coded as: (0) not resighted, (1) resighted in summer in The Netherlands, (2) resighted in winter in France, (3) resighted in winter in Iberia, (4) resighted in winter in Mauritania & Senegal. Columns refer to encounter history (H:), sample size (S:) and 'standardized' year of birth (COV:yb), calculated as ([year of birth]-2000)/10.Encounter_history_file_1994_2010.tx