Little brown myotis social networks

Bats are a group of mammals well known for forming dynamic social groups.
Studies of bat social structures are often based upon the frequency at
which bats occupy the same roosts because observing bats directly is not
always possible. However, it is not always clear how closely bats
occupying the same roost associate with each other, obscuring whether
associations result from social relationships or factors such as shared
preferences for roosts. Our goal was to determine if bats cohabitating
buildings were also found together inside roosts by using anti-collision
technology for PIT tags, which enables simultaneous detection of multiple
tags. We PIT-tagged 293 female little brown myotis (Myotis lucifugus) and
installed antennas within two buildings used as maternity roosts in
Yellowstone National Park. Antennas were positioned at roost entryways to
generate cohabitation networks and along regions of attic ceilings in each
building to generate intra-roost networks based on proximity of bats to
each other. We found that intra-roost and cohabitation networks of
buildings were significantly correlated, with the same bats tending to be
linked in both networks, but that bats cohabitating the same building
often roosted apart, leading to differing assessments of social structure.
Cohabitation rates implied that bats associate with a greater number of
their roost-mates than was supported by observations within the roost.
This caused social networks built upon roost cohabitation rates to be
denser, smaller in diameter, and contain nodes with higher average degree
centrality. These results show that roost cohabitation does not reflect
preference for roost-mates in little brown myotis, as is often inferred
from similar studies, and that social network analyses based on
cohabitation may provide misleading results.