Enhancing landscape connectivity is one of the most important tools we have for enabling species to traverse increasingly human-dominated landscapes. Given this importance, conservation researchers and practitioners have developed a wide range of approaches for mapping and measuring connectivity.
Despite this proliferation of approaches, what’s often missing is solid, empirical evidence that species use pathways that we humans flag as important for connectivity. Validating connectivity models with on-the-ground movement data and clarifying the role that protected areas (PAs) play in connectivity will be particularly important as species shift to track suitable climatic conditions.
A new study seeks to do just that by asking: When the rubber hits the road (or rather, when the paws hit the trail) how well does species actual movement correspond to connectivity models?
Using high-resolution data from 10 GPS-collared fisher (Pekania pennanti) in a central Alberta biosphere reserve, researchers compared speed (step-length) and linearity of movement (turn angle) to three traditional connectivity mapping schemes. They created test models using proximity to and density of different land cover types (e.g., coniferous forest, grasslands, cropland, and waterbodies) to represent 1) a corridor scheme, 2) a least-cost path scheme, and 3) a stepping-stone scheme that leverages protected areas across a working landscape.
The researchers hypothesized that idealized movement under each scheme would look different. For example, if fishers were using stepping stones, they would likely dwell and move freely within PAs (corresponding to low speed and highly complex paths) while traversing highly modified areas quickly and directly.
Based on the telemetry data, the fishers’ actual movement was best explained by the corridor scheme. In other words, the animals tended to move among structurally similar natural features across the landscape and did not appear to preferentially travel to or through PAs. In general, we know that PAs are critical for species persistence, but results like these underscore the importance of considering the matrix between delineated PAs in conservation priorities.
This study area happens to have a fair amount of natural vegetation on private lands beyond PAs, which contributed to landscape permeability in general, and may mean that the corridor-like movement approximates least-cost movement quite well, too. Plus, using speed and linearity of movement as evidence for a particular connectivity scheme may not hold in all landscapes or for all species. Nevertheless, this study highlights that we would be wise to use “animal-defined” corridors in prioritizing areas for enhancing or protecting connectivity whenever possible—and that our theoretical models ought to be rigorously validated with on-the-ground data.
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