Data and code from: How do synchrony in survival and productivity influence abundance synchrony in European landbirds?

Synchronous fluctuations in species’ abundance are influenced by synchrony in underlying rates of productivity and survival. However, it remains unclear how rate synchrony varies in space and time, contributes to abundance synchrony, and differs among species. Using long-term annual count (number of adults captured), adult survival and productivity (number of juveniles captured per adult) data for breeding land-birds at ringing sites across Europe, we show that synchrony is strongest and largest-scale in productivity, and weakest and smallest-scale in counts. However, counts fluctuate more synchronously with survival than they do with productivity. These patterns hold for species which do not migrate or only migrate within Europe (European-residents) and those migrating to sub-Saharan Africa (subSaharan-migrants), but the periodicity of productivity and survival synchrony is longer in European-residents than subSaharan-migrants. This suggests that survival and productivity synchrony may interact to weaken abundance fluctuations, but are influenced by environmental drivers operating over differing timescales in European-resident and subSaharan-migrantspecies.

Methods
Data were collated from 995 Euro-CES sites, spanning 12 countries across Europe, all of which use standardised mist-netting during the breeding season to measure the relative productivity and annual adult survival rates of passerine birds (Table S1). At each Euro-CES site, licensed ringers deploy a series of mist-nets in the same positions, for the same length of time, during morning and/or evening visits, typically between April-May and July-August (the season starts and ends later at higher latitudes). Data submitted as part of Euro-CES scheme follow local guidelines for ageing individuals, typically on the basis of plumage characteristics, according to strict and standardised protocols and undertaken by experienced, qualified ringers (Svensson, 2023). We only included years in which sites were (a) visited seven or more times in the season (including at least three visits in each of the first and second halves of the season), (b) had been running for five or more years and, only for estimates of productivity and apparent survival rates (hereafter survival) for each species, (c) on which two (the minimum needed to estimate these vital rates) or more adults had been captured in total, between 1998 and 2019. This therefore excludes sites which have either never caught an adult of that species or only caught one, as neither productivity nor survival rates could be estimated in these cases.