European_bird_dispersal: v1.0.1-Edispersal

EMPIRICAL NATAL AND BREEDING DISPERSAL KERNELS FOR EUROPEAN BIRDS

Guillermo Fandos 1,2 Matthew Talluto 3 Wolfgang Fiedler 4 Rob Robinson 5 Kasper Thorup 6 Damaris Zurell 1,2

1 Institute for Biochemistry and Biology, University of Potsdam, D-14469 Potsdam, Germany 2 Geography Dept., Humboldt-Universität zu Berlin, D-10099 Berlin, Germany 3 Department of Ecology, University of Innsbruck, Innsbruck, 6020, Austria 4. Max Planck Institute of Animal Behavior, D-78315 Radolfzell, and University of Konstanz, Dept. of Biology. 5. British Trust for Ornithology, The Nunnery, Thetford, IP24 2PU, United Kingdom 6. Center for Macroecology, Evolution and Climate, Globe Institute, University of Copenhagen, Denmark

ABSTRACT:

Dispersal is a key life-history trait for most species and is essential to ensure connectivity and gene flow between populations and facilitate population viability in variable environments. Despite the increasing importance of range shifts due to global change, dispersal has proved difficult to quantify, limiting empirical understanding of this phenotypic trait and wider synthesis. 

Here we introduce a statistical framework to estimate standardised dispersal kernels from biased data. Based on this, we compare empirical dispersal kernels for European breeding birds considering age (average dispersal; natal, before first breeding; and breeding dispersal, between subsequent breeding attempts) and sex (females and males) and test whether different dispersal properties are phylogenetically conserved. 

We standardised and analysed data from an extensive volunteer-based bird ring-recoveries database in Europe (EURING) by accounting for biases related to different censoring thresholds in reporting between countries and to migratory movements. Then, we fitted four widely used probability density functions in a Bayesian framework to compare and provide the best statistical descriptions of the different age and sex-specific dispersal kernels for each bird species. 

The dispersal movements of the 234 European bird species analysed were statistically best explained by heavy-tailed kernels, meaning that while most individuals disperse over short distances, long-distance dispersal is a prevalent phenomenon in almost all bird species. The phylogenetic signal in both median and long dispersal distances estimated from the best-fitted kernel was low (Pagel’s λ < 0.25), while it reached high values (Pagel’s λ >0.7) when comparing dispersal distance estimates for fat-tailed dispersal kernels. As expected in birds, natal dispersal was on average 5 km greater than breeding dispersal, but sex-biased dispersal was not detected.

Our robust analytical framework allows sound use of widely available mark-recapture data in standardised dispersal estimates. We found strong evidence that long-distance dispersal is common among European breeding bird species and across life stages. The dispersal estimates offer a first guide to selecting appropriate dispersal kernels in range expansion studies and provide new avenues to improve our understanding of the mechanisms and rules underlying dispersal events. 

Content

The workflow for estimating dispersal kernels from ring-recovery data for all of Europe

The code to develop the dispersal kernels with ring-recovery data. 

Dispersal distances for European birds.

Dispersal kernel parameters for European birds.