Network structure of avian mixed-species flocks decays with elevation and latitude across the Andes

Birds in mixed-species flocks benefit from greater foraging efficiency and reduced predation but also face costs related to competition and activity matching. Because this cost-benefit trade-off is context-dependent (e.g., abiotic conditions, habitat quality), the structure of flocks is expected to vary along elevational, latitudinal, and disturbance gradients. Specifically, we predicted that the connectivity and cohesion of flocking networks would (1) decline towards tropical latitudes and lower elevations, where competition and activity matching costs are higher, and (2) increase with lower forest cover and greater human disturbance. We analysed the structure of 84 flock networks across the Andes and assessed the effect of elevation, latitude, forest cover and human disturbance on network characteristics. We found that Andean flocks are overall open-membership systems (unstructured), though the extent of network structure varied across gradients. Elevation was the main predictor of st..., The file \"Andeanflocks.csv\" includes a comprehensive dataset of Andean mixed-species flocks surveyed in six countries, across latitudes (10°N to 41°S) and elevations (400 to 4000 m a.s.l.). It presents the species composition of 3676 independent flocks surveyed between 1976 and 2019 and organised into 84 independent sites across the Andes and adjacent lowlands (> 400 m), extracted from published and unpublished sources. 
In each study, a flock was defined as an aggregation of individuals of at least two species that move together while foraging in the original study. Similarly, all flock data across studies were collected using the ‘gambit of the group’ method, where all species observed within a single flock are assumed to be associating and are assigned reciprocal ties in the network. Thus, in our database, we do not include aggregations of frugivorous species which form in response to clumped resources and are not mobile associations.
We updated and standardised the taxonomy for a..., All analyses were conducted in R. 
The file \"CodeMSF_final.R\" includes all code required to replicate our analyses.