  Animals within groups need to coordinate their reactions to perceived
environmental features and to each other in order to safely move from one point
to another. This paper extends our previously published work on the flight
patterns of Myotis velifer that have been observed in a habitat near Johnson
City, Texas. Each evening, these bats emerge from a cave in sequences of small
groups that typically contain no more than three or four individuals, and they
thus provide ideal subjects for studying leader-follower behaviors. By
analyzing the flight paths of a group of M. velifer, the data show that the
flight behavior of a follower bat is influenced by the flight behavior of a
leader bat in a way that is not well explained by existing pursuit laws, such
as classical pursuit, constant bearing and motion camouflage. Thus we propose
an alternative steering law based on virtual loom, a concept we introduce to
capture the geometrical configuration of the leader-follower pair. It is shown
that this law may be integrated with our previously proposed vision-enabled
steering laws to synthesize trajectories, the statistics of which fit with
those of the bats in our data set. The results suggest that bats use perceived
information of both the environment and their neighbors for navigation.
