Saiga antelope regularly undertake long-distance movements varying between wide ranging nomadic movements and also more directed seasonal migrations between summer and winter ranges. Saiga movements in the open and vast grasslands are driven by unpredictable, local precipitation events followed by vegetation green-up, often resulting insaiga shifting from directed movements to more wandering movements to track green up. In May, the saiga gather in large herds for calving, which under specific conditions become hotspots for disease outbreaks that plague the species. The Ustyurt population migrates generally between wintering areas in the south and distant summering areas in the north, sometimes several hundred kilometers away. This transboundary population spends most of the year in Kazakhstan, but historically has crossed the border into Uzbekistan for the winter to avoid harsh winter conditions.