Understanding how diel and seasonal rhythms affect the movements of a small non-migratory bird
Diel and seasonal rhythms affect an animal’s environment and life history. Understanding how these rhythms influence movement increases our knowledge on how animals adjust to changing resources, environmental conditions, and risk to their survival. To better understand how diel and seasonal rhythms affect animals, we evaluated movements of Northern Bobwhite (Colinus virginianus); hereafter, bobwhite. Because bobwhite are a small non-migratory species that must cope with daily and seasonal changes in their environment year-around, they are a model species to study how diel and seasonal rhythms influence animal movement of a non-migratory species. Global positioning system data from transmitters attached to bobwhite at four wildlife management sites across Oklahoma were collected during 2019–2021. We parsed the diel data as daytime (7:00–19:00 Central Daylight Savings Time [CDT]) and nighttime (19:00–7:00 CDT), and diurnal (sunrise–sunset) and nocturnal (sunset–sunrise) as well as by astronomical season. We calculated three movement metrics: net displacement (Euclidean distance from the starting fix to the ending fix of a path which encompasses consecutive relocations in a time series of geographic fixes), cumulative distance (sum of all Euclidean distances between each consecutive fix along the path), and hourly movement. We modeled the data using a generalized linear mixed-modeling approach. Across season, model predictions showed that net displacement was highest during spring, and daytime cumulative distance slowly increased as the year progressed. Bobwhite had two movement peaks during the diurnal period, one during 9:00–10:00 and the other during 17:00–20:00 depending on the season. Despite being diurnal, bobwhite occasionally made nocturnal movements, likely in response to a disturbance by a predator, inclement weather, or energetic demands. Movement peaks during the diurnal period may reflect changes in behavior in response to energy requirements, predator risk, and changes in air temperature. Life history events, likely cause seasonal differences in movement. This study furthers our understanding on how animals move daily and seasonally suggesting the importance of analyzing movement across the entire year because animals move differently across the day and year.
Oklahoma Department of Wildlife Conservation
Hatch Program funding, Award: OKL03193