Population and demographic synchrony in European land birds

Here we present the results of the analysis of synchrony in annual population count, productivity, and survival for 26 species across 995 sites monitored from 1998 to 2019 under the European Constant Effort Scheme (CES) (Morrison et al., 2025).

Datasets:
European-level Constant Effort Scheme (CES) site ringing data collected for 26 species across a total of 995 sites from 1998 to 2019. The exact number of sites used to produce estimates of synchrony in count, productivity, and survival varies due to differing inclusion thresholds, see Morrison et al. (2025) for more details.
Analysis:

CES sites were aggregated into resolutions of 25 km2, 50 km2, and 100 km2. Detrended annual estimates of count, productivity and survival were estimated for each cell at each resolution. Pearson correlations were then carried out between time-series across all pairs of grid cells. Spatial correlograms were fitted for each grid cell to model the Pearson correlation coefficients as a smoothed function of the distance between each pair of grid cells.

Metrics:

The following metrics were extracted from the correlograms:

1. Relative scale - the distance over which population fluctuations remain correlated relative to range size.

2. Strength - the estimated similarity of time series (measured as a magnitude of correlation) at a distance of zero between pairs of cells.