Josh Lawler and colleagues take us on a pole-to-pole tour of future animal movement in their new paper in Ecology Letters. They examine how nearly 3000 species’ distributions will shift as a result of climate change and whether high-use movement corridors are in conflict with existing human-dominated land use. For each species, Lawler and colleagues modeled suitable distributions under a baseline (1961-1990) and future climate scenarios (2071-2100) at a 50 x 50-kilometer grain. Using Circuitscape, each species’ movement from current to future distributions was modeled while accounting for barriers from human land-use. Average movements across all species at each grain are mapped to show general patterns of movement throughout the Americas. The results highlight regions that are needed for animal movement but have high human impact (like the Southeast US) and places where more species need to move outside their current range to track suitable climate (flatter biomes compared to mountains).
What lessons does this bird’s-eye view give for more local conservation efforts? The framework laid out in this study could guide projects with a smaller scope, perhaps for a regional network of protected areas in which managers want to find movement corridors across a landscape with human land-use obstacles. Lawler and colleagues also demonstrate one feature of Circuitscape that distinguishes it from other movement analysis software: rather than simply finding a least-cost path between two points, it can model likely movement between two areas of any size (in this case between current and future species distributions). I also think this study could be repeated with greater detail as computing power increases and as new datasets are created, such as a recent paper by Jenkins and colleagues in PNAS that updates terrestrial vertebrate ranges to a 10 x 10-kilometer resolution.
One criticism is that future human land-use is not taken into account, as Lawler and colleagues use a human impact dataset published a decade ago. Some of the regions shown to have conflicts between animal movement and human land-use, like the Southeast US, also have rapid urban expansion. Uncertainty over how our footprint will change makes any projection of future animal movement corridors more difficult.
Lawler, J. J., A. S. Ruesch, J. D. Olden, B. H. McRae. 2013. Projected climate-driven faunal movement routes. Ecology Letters 16(8): 1014-1022.
Jenkins, C., S. L. Pimm, L. N. Joppa. 2013. Global patterns of terrestrial vertebrate diversity and conservations. Proceedings of the National Academy of Sciences 110(28): E2602-E2610.