Cumulative impacts of roads and energy infrastructure on grassland songbirds

Comparing impacts of co-occurring anthropogenic features is necessary for regional planning and can help identify mechanisms of negative impacts of development on wildlife. Because of the vast abundance of anthropogenic features in the Northern Great Plains, their combined negative impacts on songbird habitat use (e.g., abundance) and productivity (e.g., nesting success and clutch size) could exacerbate the decline of songbird populations. We compared the cumulative effects of energy-related infrastructure (oil wells, shallow gas wells, and roads) on habitat use and productivity of songbirds across a 120 × 180 km region in southern Alberta, Canada. We examined effects on Chestnut-collared Longspur (Calcarius ornatus) and Sprague's Pipit (Anthus spragueii), both of which are listed as Threatened in Canada, and Savannah Sparrow (Passerculus sandwichensis), Vesper Sparrow (Pooecetes gramineus), and Western Meadowlark (Sturnella neglecta). Using piecewise regressions and generalized linear models, we estimated effects of distance from infrastructure and shallow gas well density on the habitat use and productivity of each species. We then used these analyses to quantify the availability of habitat suitable for settlement and breeding throughout our study region. Shallow gas wells, which are more abundant, affected a larger geographic area than oil wells, but oil wells were associated with the added impacts of roads. Our analyses suggest that impacts of wells on songbirds are not caused by industrial noise because individual shallow gas wells, which produce no mechanical noise, had similar impacts to noisy oil wells. Our results highlight the importance of regional plans that consider the impacts of multiple co-occurring anthropogenic features in working landscapes.