Linear infrastructure drives biotic homogenization among bird species of a tropical dry forest

Linear infrastructures (LIs) such as roads, railroads, and powerlines are
expanding rapidly around the globe. While most future developments are
projected to take place in tropical regions, available information on
impacts of LIs is biased towards single species studies of solely road
impacts in temperate regions. Therefore, we investigated impacts of three
types of LIs (road, railroad, and powerline) on the bird community of a
tropical dry forest. Point-count surveys to record avian richness and
abundance were conducted at 80 plots that were spatially stratified to
include sites proximate to all possible LI combinations. Five measures of
vegetation structure were collected at each plot as well. We then assessed
the relationship between the bird community (i.e., richness, abundance,
composition) and distance to each LI type while accounting for variation
in vegetation structure. Species richness and abundance both declined
significantly (25% and 20%, respectively) from edge habitat next to
railroad to interior forest plots, while community composition was
significantly altered by the distance to all three LIs. Road and railroad
(both forms of dynamic infrastructure with moving vehicles) had similar
effects on the bird community that contrasted with those of powerline (a
type of static infrastructure). The resulting ordination reveled that Sri
Lankan endemics are significantly disfavored by LI proximity, while
species that now have naturalized populations across the globe are most
often found proximal to LI. Our results emphasize that LI drive biotic
homogenization by favoring these increasingly widespread species at the
expense of unique elements of the biota.