Data from: Interaction networks of avian mixed-species flocks along elevation in the tropical Andes

Ecological communities are comprised of species that interact with each
other and those interactions ultimately generate community structure.
Network theory provides a useful framework to study communities, by
simultaneously considering species composition and the interactions among
species. In this study, I use mixed-species flocks as model systems to
gain insights on community and network structure. Specifically, I use
co-occurrence network analyses to explore if avian mixed-species flocks
change in richness and composition and/or in network structure and
pair-wise associations, across elevations in the tropical Andes of
Bolivia. Networks of flocking species changed both in composition and in
the frequency and realization of pair-wise interactions across elevations,
but changes in pair-wise associations explained most of network turnover
along elevation. Pair-wise interactions changed rapidly, with shared
species changing in position and importance within the network. Network
dissimilarity was mostly explained by changes in the nature of
associations rather than by differences in composition. Altogether,
results show that montane mixed-species flocks are composed of loosely
connected species and that most species have the potential of switching
associations, often increasing in association strength at high elevations
(up to 3150m). Networks increased in connectivity and cohesion with
elevation; flocks in lower elevations had more connections and these were
less even. Above 3150 m asl, there was rapid decay suggesting that flocks
above this critical point are less connected and cohesive. This study
exemplifies how combining community, network and pair-wise analyses can
provide a more holistic view on the responses of species and assemblages
to environmental gradients.