Are bison movements dependent on season and time of day? Investigating movement across two complex grasslands

Abstract

The American plains bison (Bison bison) is an iconic herbivore on North American grasslands, yet many questions surrounding their basic biology remain unanswered. We analyzed fine-resolution movement data (12 minute) from two of the largest remaining prairie tracts in the Great Plains of North America to address whether bison movement and distance travelled are affected by seasonal or diurnal rhythms. We fit binomial movement and movement distance data to generalized linear mixed models to test whether site, season, or time of day affected movement. Our top models included season-site and season-time of day interactions as fixed effects. Overall, bison were more likely to move during the day than at night regardless of season or site. There was considerable overlap between our sites across most seasons, with the strongest divergence occurring in autumn for movement probability and distance. During the summer, daytime bison movement declined in favor of nighttime movement, potentially in response to high temperatures. Day and nighttime movement distance and probability both were lowest in the winter. That site alone was not a significant predictor of bison movement or movement distance may suggest that their response to seasonal and diurnal rhythms is biologically innate. Therefore, we conclude that season and time of day should be considered in future bison movement analyses. Here, we present the first replicated analysis of fine-resolution, seasonal, and diurnal bison movements across two large complex landscapes using a long-term dataset. As ungulate behavior changes in response to the Anthropocene, filling the knowledge gaps in their basic biology is critical to their continued conservation.

Understanding how diel and seasonal rhythms affect the movements of a small non‐migratory bird

“…Furthermore, this pattern was consistent across all sites suggesting a broad‐scale response to seasonal rhythms. This is contrary to previous research that found that bison at different sites moved differently during the fall, which McMillan et al (2021) suggested was caused by topographical differences between these sites. Seasonal rhythms appeared to influence bobwhite net displacement the most during spring.…”

“…Furthermore, our ability to collect movement data at fine‐temporal scales was limited by VHF telemetry. Given the technological advancements in telemetry and accessibility of GPS technology, scientists and managers are now able to better understand movement patterns at fine‐temporal scales (Cagnacci et al, 2010; McMillan et al, 2021). In fact, GPS technology has significantly increased our understanding of how diel and seasonal rhythms affect movements of large mammals and large birds (Cagnacci et al, 2010; McMillan et al, 2021; Owen‐Smith & Goodall, 2014; Zavalaga et al, 2011).…”

“…Given the relationship between seasonal rhythms and life histories of animals (i.e., timing of different life history events), we would expect bobwhite movements to be altered by seasonal rhythms. In fact, recent studies on other animals have shown movement patterns are related to seasonal rhythms (Lenz et al, 2015; McMillan et al, 2021).…”

“…Diel and seasonal rhythms have been shown to influence the foraging patterns of animals (Lenz et al, 2015; Zavalaga et al, 2011). For example, foraging competition, changes in resources, thermal constraints, and rates of digestive passage caused by diel and seasonal rhythms have been found to alter the movements of some animals (Lenz et al, 2015; McMillan et al, 2021; Owen‐Smith & Goodall, 2014; Zavalaga et al, 2011). Furthermore, environmental changes (i.e., lower temperatures and snowfall) driven by seasonal rhythms influence the diel and seasonal movements of some animals, allowing individuals to avoid predation and exposure to harsh winters, as well as to take advantage of available resources (Ellington et al, 2020; Komal et al, 2017; Somveille et al, 2015).…”

“…Other factors vary with these rhythms including daylight, age of animal, and hormone levels, further stating the importance of studying movement patterns broadly across these rhythms (Myers et al, 2006). Lastly, conspecific individuals at different sites can move differently in response to seasonal rhythms (McMillan et al, 2021). For example, bison ( Bison bison ) at two sites moved differently during the fall, which McMillan et al (2021) suggested was related to topographical differences between the sites.…”