Integrating stable isotopes, parasite and ring-reencounter data to quantify migratory connectivity - a case study with Barn Swallows breeding in Switzerland, Germany, Sweden and Finland
von Rönn, Jan; Grüebler, Martin U.; Fransson, Thord; Korner-Nievergelt, Fränzi (2021), Integrating stable isotopes, parasite and ring-reencounter data to quantify migratory connectivity - a case study with Barn Swallows breeding in Switzerland, Germany, Sweden and Finland, Dryad, Dataset, https://doi.org/10.5061/dryad.3xsj3txbt
Ecosystems around the world are connected by seasonal migration. The migrant animals themselves are influenced by migratory connectivity through effects on the individual and the population level. Measuring migratory connectivity is notoriously difficult due to the simple requirement of data conveying information about the non-breeding distribution of many individuals from several breeding populations. Explicit integration of data derived from different methods increases the precision and the reliability of parameter estimates.
We combine ring-reencounter, stable isotope and blood parasite data of Barn Swallows Hirundo rustica in a single integrated model to estimate migratory connectivity for three large scale breeding populations across a latitudinal gradient from Central Europe and Scandinavia. To this end, we integrated a non-Markovian multi-state mark-recovery model for the ring-reencounter data with normal and binomial mixture models for the stable isotope and parasite data.
The integration of different data sources within a mark-recapture modelling framework enables the most precise quantification of migratory connectivity on the given broad spatial scale. The results show that northern breeding populations and Southern Africa as well as southern breeding populations and Western-Central Africa are more strongly connected through Barn Swallow migration than central European breeding populations with any of the African wintering areas. The non-breeding distribution of Barn Swallows from central European breeding populations seems to be a mixture of those populations breeding further North and South, indicating a migratory divide.
raw_isotope_data.txt: The site key defines the sampling site of the feather sample. Codes are given in Figure S1.
rcode_for_running_model.r: Complete R code ready to load the data and run the model in Jags
recovery_isotope_parasite_data.rda: Compiled data (ringing and ring re-encounter data, parasite data and z-transformed stable isotope data) to be read into R using the r-codefile "rcode_for_running_model.r".
jags_code.txt: Jags code of the model