Data from: Drivers of spatiotemporal variation in survival in a flyway population: a multi-colony study

1. Spatio-temporal variation in population dynamics of migratory
populations is shaped by exposure to different environments during the
annual cycle. Hence, exposure to similar environments should translate
into synchrony in vital rates. Despite a wide-ranging breeding population,
the Baltic/Wadden Sea flyway population of eiders (Somateria m.
mollissima) shares wintering grounds in the southern Baltic Sea, inner
Danish waters and the Wadden Sea; different colonies within this flyway
population are therefore likely to exhibit some degree of synchrony in
vital rates. 2. Here we used capture-recapture-recovery data to
investigate the impact of hunting, winter climate (the North-Atlantic
Oscillation Index), winter temperature, nitrogen runoff, autumn-winter
body condition of blue mussels Mytilus spp., natural predation and
epidemic disease (avian cholera) on annual survival of adult females in
ten study colonies distributed between the Netherlands and Finland.
Moreover, we tested how the degree of similarity in spatial winter
distributions affected the degree of similarity in annual survival among
colonies. 3. None of the covariates universally affected female survival.
While the quality of blue mussels in the wintering area explained almost
40 % of the variation in survival of eiders breeding on Christiansø in the
south-western Baltic Sea, incidence of epidemic disease explained >
60 % in two affected colonies. Furthermore, the spatial winter
distribution did not appreciably influence annual survival rates in these
ten colonies. 4. The lack of universal effects of spatial winter
distribution and winter conditions on survival suggests that local
breeding conditions may be more important, and hence prime targets for
conservation efforts. Better monitoring of e.g. food quality, predation
pressure and epidemic disease at the time of breeding could be the key to
better understand the population dynamics in this endangered flyway
population.