Synchrony in Svalbard reindeer population dynamics

We examined potential synchrony in the growth rates of three Svalbard reindeer (Rangifer tarandus platyrhynchus) populations and tested whether this pattern may result from correlated environmental variation. Two neighbouring populations had synchronized dynamics during the study period, while a more distant population showed different temporal variation. Climatic forcing (the Moran effect) was a likely synchronizing mechanism in combination with contrasting density-dependence patterns between the synchronous and asynchronous populations. Local climate was a more important synchronizing agent than a regional climate index (the Arctic Oscillation). Nevertheless, our results also suggest that variation in climate at a large scale may be important. Based on indirect measurements of dispersal/migration, our findings indicate that this factor does not play a key role in the spatial synchrony of Svalbard reindeer population dynamics.