Developing Grassland Songbird Management Targets for Multi-Species Conservation on Native Mixed-Grass Prairie

Abstract

Grassland birds are declining at steeper rates than birds from nearly every other habitat type, and the primary reasons for these declines are loss and degradation of native grasslands. Moisture, along with other environmental conditions such as soil type, topography, fire, and grazing, play important roles in determining the extent of habitat features important to grassland songbirds. I examined the associations between the abundance/occurrence of 14 grassland songbird species and vegetation characteristics along a moisture gradient in southwest Saskatchewan. Associations with at least one vegetation characteristic changed along the moisture gradient for 12 of the 14 species. Songbird abundance/occurrence was typically greater in areas with dense cover at drier sites along the moisture gradient when overall cover was sparse and greater in areas with sparser cover at wetter sites when overall cover was dense; however, absolute values for vegetation characteristics associated with peak abundance/occurrence often remained similar along the moisture gradient. The umbrella species concept is based on the premise that the conservation of a single species can also aid in conservation of a wide range of other co-occurring species with overlapping habitat requirements. I examined how the vegetation attributes of greater sage-grouse (Centrocercus urophasianus) critical habitat influenced grassland songbirds, and whether sage-grouse could potentially serve as an umbrella species for the grassland songbird community at the northern extent of the sage-grouse range. I found that abundance of Sprague’s pipit (Anthus spragueii) and Baird’s sparrow (Ammodramus bairdii) was lower and abundance of lark bunting (Calamospiza melanocorys) was higher within greater sage-grouse critical habitat in comparison to a 1.6 km buffer surrounding critical habitat. The abundance of all endemic grassland songbirds, except lark bunting, was negatively associated with vegetation attributes that characterized sage-grouse critical habitat (i.e., shrub and sagebrush cover). The vegetation characteristics associated with shrub-steppe songbirds and several grassland generalists overlapped with vegetation characteristics that defined greater sage-grouse critical habitat. Greater sage-grouse conservation is likely to have a positive influence on shrub-tolerant species, such as lark bunting, and a neutral or positive effect on generalist grassland species, but will provide few benefits to other grassland species at risk.