We know that animals select habitat at multiple spatial scales, but typically, we try to understand why we find animals in some but not all locations by only measuring attributes of territories and home ranges. How important is the landscape context? and what features do some of the most threatened birds of tallgrass prairies respond to?
This project was the focus on Mark Herse’s MS thesis. We found that even in the Flint Hills of Eastern Kansas where the last large tracts of prairie remain, Henslow’s Sparrows are extremely rare, move around within breeding seasons, and select habitat at far larger spatial scales than that of their territories. Rather surprisingly, when they arrive in spring, they settle disproportionately frequently in Conservation Reserve Program (CRP) fields, a habitat typically regarded as low-quality compared to native prairie. This is likely due to the prevalence of prescribed spring fires to increase forage quality for cattle. As the season progresses, they move to sites surrounded by large expanses of native prairie (Herse et al. 2017, Landscape Ecology).
Capitalizing on the astounding number of point-count surveys conducted for the Henslow’s Sparrow project, we were able to use abundance data from the much more common Grasshopper Sparrow to test long-standing ideas about the relative importance of habitat area, and the configuration of habitat patches. Mark devised a novel way to distinguish these analytically, and found that indeed, the amount of ‘core’ habitat (grassland area at least 60 m from edges) was a far better predictor of abundance in this species (Herse et al. 2018, JAppliedEcol).
Finally, using data from four declining species, we determined the landscape contexts in which fragmentation effects are strongest for grassland birds. Because most of these species are apparently not at all dispersal-limited, fragmentation effects may be quite different in prairies as compared to forested ecosystems. The final paper in this series was published in Landscape Ecology in 2020.