Moody blues?: Sources of individual variation in movement behavior of Fender's blue butterflies

Background/Question/Methods

Individual variation in movement behavior has two components; variation among individuals (personalities) and variations among behavioral states within an individual (moods). Understanding these two types of variation have important conservation implications. Considering individual variation allows for more accurate estimates of diffusion, habitat connectivity and critical minimum patch size and quantifying within individual variation could allow us to infer behavioral states from movement paths. In this study, we analyzed a set of 119 flight path observations from 68 female Fender’s blue butterflies. We had both spatial coordinates and detailed behavioral observations for each flight path. We used the behavioral observation to break the flight paths into three behavioral states, oviposition, nectaring and flying. We used GLMM to quantify how much move length, turn angle and time per move varied among behavioral states and among individuals.  

Results/Conclusions

Preliminary analyses indicated that butterflies exhibit both moods and personalities. Move lengths and turn angles varied among behavioral states with paths having shorter steps and larger turning angles during the oviposition behavioral state, marginally larger steps and smaller turn angles during nectaring and the largest steps and straightest paths during the flight behavioral state. Overall there was more variation among individuals than among behavioral states. Conversely, time per move was more dependent on mood than personality, though this might be a consequence of our experimental design. For Fender’s blues both moods and personalities contribute to individual variation in movement, which would make movement overall more leptokurtic than simple diffusion models predict. Studies have suggested that you can use differences among moods as a latent variable; in the case of Fender’s blue, it would be difficult to discriminate differences among behavioral states from differences among personalities.