Bison movement response to weather

Animal movement patterns are affected by complex interactions between
biotic and abiotic landscape conditions, and these patterns are being
altered by weather variability associated with a changing climate. Some
animals, like the American plains bison (Bison bison L.; hereafter, plains
bison), are considered keystone species, thus their response to weather
variability may alter ecosystem structure and biodiversity patterns. Many
movement studies of plains bison and other ungulates have focused on
point‐pattern analyses (e.g., resource‐selection) that have provided
information about where these animals move, but information about when or
why these animals move is limited. For example, information surrounding
the influence of weather on plains bison movement in response to weather
is limited but has important implications for their conservation in a
changing climate. To explore how movement distance is affected by weather
patterns and drought, we utilized 12‐min GPS data from two of the largest
plains bison herds in North America to model their response to weather and
drought parameters using generalized additive mixed models. Distance moved
was best predicted by air temperature, wind speed, and rainfall. However,
air temperature best explained the variation in distance moved compared to
any other single parameter we measured, predicting a 48% decrease in
movement rates above 28°C. Moreover, severe drought (as indicated by 25‐cm
depth soil moisture) better predicted movement distance than moderate
drought. The strong influence of weather and drought on plains bison
movements observed in our study suggests that shifting climate and weather
patterns will likely affect plains bison movement patterns, further
complicating conservation efforts for this wide‐ranging keystone species.
Moreover, changes in plains bison movement patterns may have cascading
effects for grassland ecosystem structure, function, and biodiversity.
Plains bison and grassland conservation efforts need to be proactive and
adaptive when considering the implications of a changing climate on bison
movement patterns.