Analysis of temporal patterns in animal movement networks

1. Understanding how animal movements change across space and time is a
fundamental question in ecology. While classical analyses of trajectories
give insightful descriptors of spatial patterns, a satisfying method for
assessing the temporal succession of such patterns is lacking.  
2. Network analyses are increasingly used to capture properties of complex
animal trajectories in simple graphical metrics. Here, building on this
approach, we introduce a method that incorporates time into movement
network analyses based on temporal sequences of network motifs.  
3. We illustrate our method using four example trajectories (bumblebee,
black kite, roe deer, wolf) collected with different technologies
(harmonic radar, platform terminal transmitter, global positioning
system). First, we transformed each trajectory into a spatial network by
defining the animal’s coordinates as nodes and movements in between as
edges. Second, we extracted temporal sequences of network motifs from each
movement network and compare the resulting behavioural profiles to
topological features of the original trajectory. Finally, we compared each
sequence of motifs with simulated Brownian and Lévy random motions to
statistically determine differences between trajectories and classical
movement models.   4. Our analysis of the temporal sequences of
network motifs in individual movement networks revealed successions of
spatial patterns corresponding to changes in behavioural modes that can be
attributed to specific spatio-temporal events of each animal trajectory.
Future applications of our method to multi-layered movement and social
network analysis yield considerable promises for extending the study of
complex movement patterns at the population level.