Threshold responses of grassland and sagebrush birds to patterns of disturbance created by an ecosystem engineer

• Published in: Landscape ecology 2019-04, Vol.34 (4), p.895-909
• Main Authors: Duchardt, Courtney J., Augustine, David J., Beck, Jeffrey L.
• Format: Article
• Language: English
• Subjects: Abundance; Biomedical and Life Sciences; Birds; Colonies; Disturbance; Ecology; Environmental Management; Grasslands; Habitats; Identification methods; Landscape Ecology; Landscape/Regional and Urban Planning; Life Sciences; Nature Conservation; Nonlinear response; Plant communities; Prairie dogs; Rangelands; Research Article; Shrublands; Species; Sustainable Development; Thresholds; Wildlife conservation
• ISSN: 0921-2973; 1572-9761
• DOI: 10.1007/s10980-019-00813-y

Context Burrowing mammals play a role in rangeland disturbance worldwide, enhancing habitat for certain species while negatively affecting others. However, little is known concerning effects of disturbance spatial pattern on co-occuring fauna. In the North American Great Plains, colonial black-tailed prairie dogs ( Cynomys ludovicianus ) may enhance habitat for one suite of birds while degrading habitat for others. Objectives We examined the influence of prairie dogs on birds in a mosaic grassland–shrubland landscape. We evaluated how birds associated with shortgrass, midgrass, and sagebrush ( Artemisia spp.) plant communities respond to spatial pattern of prairie dog disturbance and identified thresholds where abundance changes. Methods We surveyed bird abundance on prairie dog colonies of varying sizes and shapes, across colony edges into undisturbed habitat, and within undisturbed sagebrush in northeastern Wyoming. We modeled species responses to colony presence, distance to colony edge, and total area and edge density of colonies at four spatial scales (100 m, 225 m, 500 m, 1000 m). Results Sagebrush specialists like Brewer’s sparrow ( Spizella breweri ) and sage thrasher ( Oreoscoptes montanus) were 4.5 times more abundant in undisturbed shrublands. Conversely, the shortgrass-specialist mountain plover ( Charadrius montanus ) was abundant on colonies but showed a non-linear response to colony edge, increasing in abundance up to 600 m from edges then declining further towards colony cores. Conclusions While some species may be broadly intolerant to disturbance, disturbance-dependent birds can display a “goldilocks syndrome” relative to disturbance size. As such, management for multiple species of conservation concern can be optimized relative to other goals by identifying thresholds associated with the effect of disturbance.