Behavioral buffering of extreme weather events in a high-Arctic herbivore

English. As global warming advances, there is a growing concern about the impact of extreme weatherevents on ecosystems. In the Arctic, more frequent unseasonal warm spells and rain-on-snoweventsin winter cause changes in snow-packproperties, including ground icing. Such extreme weather eventsare known to have severe effects across trophic levels, for instance, causing die-offsof large herbivores.However, the extent to which individuals and populations are able to buffer such events through behavioralplasticity is poorly understood. Here, we analyze responses in space use to rain-on-snowand icingevents, and their fitness correlates, in wild reindeer in high-ArcticSvalbard. Range displacement amongGPS-collaredfemales occurred mainly in icy winters to areas with less ice, lower over-winterbody massloss, lower mortality rate, and higher subsequent fecundity, than the departure area. Our study providesrare empirical evidence that mammals may buffer negative effects of climate change and extreme weatherevents by adjusting behavior in highly stochastic environments. Under global warming, behavioral bufferingmay be important for the long-termpopulation persistence in mobile species with long generationtime and therefore limited ability for rapid evolutionary adaptation.Arctic; climate; GPS; ice; ideal-free distribution; migration; movement; Rangifer tarandus platyrhynchus;space use; Svalbard; Svalbard reindeer; time-to-event analysis.

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