Influences of Precipitation on Bison Weights in the Northern Great Plains

Abstract

We evaluated relationships between bison weights and prior precipitation during 1983 to 2015 for Wind Cave and 1998 to 2015 for Badlands National Parks. We generally found positive correlations between weights for most sex and age cohorts and precipitation during each of the preceding 7 years. The association was strongest for yearlings. We speculate that rainfall several years prior can improve forage, which affects the condition of cows, which affects neonatal weights and subsequent growth of young bison. Correlations were stronger for a moving average of previous precipitation, suggesting a cumulative effect. Our analysis demonstrates the importance of long-term monitoring for better understanding of grassland ecosystems.