Natural Gas Development and Grassland Songbird Abundance in Southwestern Saskatchewan: The Impact of Gas Wells and Cumulative Disturbance

Abstract

The quantity and quality of remaining grasslands in southwestern Saskatchewan, Canada, are threatened by expansion of natural gas development. The number of natural gas wells nearly tripled between 1997 and 2007. Current management strategies do not consider the effect of natural gas development on grassland birds because the impacts are not known. I examined grassland songbirds and vegetation structure across an area with a gradient of gas-well densities to determine whether (1) density and proximity of gas wells influence abundance and occurrence of grassland songbirds or (2) the relative and cumulative effect of different types of anthropogenic disturbances associated with natural gas development (roads, trails, pipelines, gas well size, soil compaction, and crested wheatgrass coverage) influence the abundance and occurrence of grassland songbirds in south-western Saskatchewan. I conducted 1250 point counts in 105 plots (259 ha each) at varying distances from natural gas wells, which ranged from 0-25 natural gas wells per 259 ha per plot. I recorded 7 grassland songbird species: Horned Lark (Eremophilus alpestris), Sprague’s Pipit (Anthus spragueii), Chestnut-collared Longspur (Calcarius ornatus), McCown’s Longspur (Rhynchophanes mccownii), Savannah Sparrow (Passerculus sandwichensis), Grasshopper Sparrow (Ammodramus savannarum) and Baird’s Sparrow (Ammodramus bairdii). Responses of grassland songbirds to natural gas well density, proximity, and types of disturbance structures varied among species. Overall, Sprague’s Pipit, McCown’s Longspur and Grasshopper Sparrow responded negatively to natural gas development, Chestnut-collared Longspur, Savannah and Baird’s Sparrows exhibited mixed effects, and Horned Larks consistently responded positively to natural gas development. My results also indicate that natural gas ii development affected vegetation structure, which likely influences grassland bird abundance. The species-specific responses to natural gas disturbance seemed closely linked to the associated changes in vegetation structure. As natural gas development increases on Agriculture and Agri-Foods Canada pastures and on other grasslands, the effects on grassland songbirds will likely become more pronounced. My research is the first to quantify the relationship between songbird abundance, vegetation structure, and natural gas development. Further work is necessary to assess the effects of natural gas development on grassland songbirds and other species as energy development proceeds.