Funding. The study was funded by NERC (project nos. NE/L007665/1 and NE/T007/354/1). Data collection was financially supported by the Ministry of Culture of the Czech Republic (DKRVO 2019–2023/6.VIII.b, National Museum, 00023272) and the JNCC (on behalf of Natural England, Natural Resources Wales, Scottish Natural Heritage and the Department of the Environment, Northern Ireland).

Acknowledgements. This study was made possible by strong pan-European collaborations and friendships and is the result of thousands of hours of fieldwork by dedicated volunteers. Analysis was carried out on the High Performance Computing Cluster supported by the Research and Specialist Computing Support service at the University of East Anglia.

The dynamics of wild populations are governed by demographic rates which vary spatially and/or temporally in response to environmental conditions. Conservation actions for widespread but declining populations could potentially exploit this variation to target locations (or years) in which rates are low, but only if consistent spatial or temporal variation in demographic rates occurs. Using long-term demographic data for wild birds across Europe, we show that productivity tends to vary between sites (consistently across years), while survival rates tend to vary between years (consistently across sites), and that spatial synchrony is more common in survival than productivity. Identifying the conditions associated with low demographic rates could therefore facilitate spatially targeted actions to improve productivity or (less feasibly) forecasting and temporally targeting actions to boost survival. Decomposing spatio-temporal variation in demography can thus be a powerful tool for informing conservation policy and for revealing appropriate scales for actions to influence demographic rates.