Continental synchrony and local responses: Climatic effects on spatiotemporal patterns of calving in a social ungulate

Abstract Warming temperatures and advancing spring are affecting annual snow ice cycles, as well plant phenology, across the Arctic boreal regions. These changes may be linked to observed population declines in wildlife, including barren‐ground caribou ( Rangifer tarandus ), a key species of environments. We quantified how caribou, characteristically both gregarious migratory, synchronize births time aggregate space investigated these tactics influenced by variable weather conditions. analyzed movement patterns infer calving dates for 747 collared female from seven herds northern North America, totaling 1255 events over 15‐year period. By relating local conditions during 1‐year period preceding calving, we examined timing ability reach their central area. documented continental‐scale synchrony but was greatest within an individual herd given year. Weather before gestation had contrasting effects on location calving. Notably, combination unfavorable winter spring, pre‐calving migration, resulted late arrival area or failure greater Though differently among herds, warm low wind speed, which associated with soft, deep snow, generally affected areas give birth. Delayed have potential indirect consequences, reduced calf survival. Overall, detected considerable variability years no significant trend earlier even broad indicators phenology earlier. Our results emphasize importance monitoring examine summer subsequent reproductive success.