LAUSR

Grassland bird species have declined more than birds of any other region in North America and industrial development may exert further pressure on these species. We evaluated effects of conventional natural gas infrastructure on the relative abundances of grassland songbirds in southeastern Alberta, Canada at sites with shallow gas well pad densities ranging from 0 to 16 pads/258 ha (0–24 well heads/258 ha). Conventional gas wells have a relatively small footprint and minimal associated noise and maintenance activities, allowing us to focus on effects of the infrastructure itself and vegetation surrounding wells. We conducted fixed-radius point counts and vegetation sampling at 34 sites in 2010 and 40 sites in 2011. We used generalized linear mixed models and information theory to evaluate effects of infrastructure on birds. Relative abundances of vesper sparrow (Pooecetes gramineus) and western meadowlark (Sturnella neglecta) increased near gas wells, whereas abundance of the threatened Sprague's pipit (Anthus spragueii) declined. Vegetation near infrastructure was shorter and sparser than locations farther from wells, but discrepancies with avian habitat preferences suggest that, in contrast to conclusions of previous studies, vegetation structure could not explain responses to infrastructure by birds. Instead, gas wells may have acted as artificial shrubs because they attracted species that use vegetation for perching but were avoided by species that avoid shrubs. Our results suggest that observed effects were a direct result of the presence of wells and associated fencing, and thus risk mitigation should focus on reducing the extent of aboveground infrastructure. © 2017 The Wildlife Society.