An important theme of ecology is understanding how animals move through their landscape and inferring the strategies of resource acquisition for fitness enhancement. Availability of resources varies across space and time on heterogeneous landscapes. Animal movement and habitat selection may vary at multiple spatial and temporal scales in response to spatiotemporal variation in resource variability. Eastern wild turkeys (Meleagris gallapavo silvestris) are mobile habitat generalist that do not fly long distances; and thus, are a model species for evaluating the responses of movement to spatiotemporal variability on the landscape. We hypothesize that scales of area-restricted search (ARS) will change from May to August because of environmental changes on the landscape. We used GPS transmitters to track eight wild turkeys at a 15- or 30-min relocation frequency for a 14-hour daily duty cycle in Copiah County, Mississipi. Using GPS-tracked daily movement trajectories from individuals, we identified the monthly spatial scale of ARS through First Passage Time (FPT) analysis to understand monthly changes in summer space-use strategies of wild turkeys. We also identified the ARS locations of high FPT values via segmentation algorithms to represent the forage patches and evaluate spatial variations in foraging-like activities of wild turkeys.
Results/Conclusions
From May to August, the ARS scale peaked at about 100m and the variance in FPT did not change substantially until 200m, indicating that wild turkeys conducted daily foraging-like movements in an area or forage patch of a 100- to 200-m radius. Wild turkeys used multiple ARS patches throughout the duration of a day. Although there were no changes in the primary ARS scale between months, the secondary ARS scale varied by month with the secondary ARS scales of about 700m for May, 800m for June and August, and 500m for July. This secondary peak may be attributed to average daily home range size. Individuals seemed to forage daily at the same spatial scale during summer; however, their daily home range size could be changing between months due to fluctuations in resource availability or changes in their behavior such as nesting, brooding, or flocking behaviors. Fine-scale GPS tracking technology allows us to evaluate daily movement and habitat selection using FPT analysis and continuous hidden Markov models (HMM). HMMs will help us determine behavior based on movement patterns in distance moved and turning angles to infer where and when birds are exhibiting foraging-like behavior.