Carnivore-mediated seed crossings are more likely on roadkill hotspots

Roadkill hotspots concentrate animal movement and mortality, but whether they also concentrate animal-mediated seed flow (a key pathway of plant connectivity) remains unknown. In Mediterranean oak woodlands of southern Portugal, we used seed mimics to test how road type (paved vs. unpaved) and road-forest context (edge vs. non-edge) shape carnivore-mediated seed crossings, and whether crossings coincide with roadkill hotspots detected by kernel density analysis. Bayesian logistic models indicated that seed-crossing probability was about twice as high on unpaved as on paved roads (predicted means 0.28 vs. 0.14), with weaker evidence for a negative edge effect. Crossing probability also tended to increase with carnivore abundance and distance to streams, and decrease with rodent density, albeit with some uncertainty. Crucially, paved sections intersecting roadkill hotspots showed nearly threefold higher predicted crossing probabilities than non-hotspot sections (0.51 vs. 0.18). These findings support hotspot-guided mitigation on paved, non-edge segments (for example targeted speed management, fencing that funnels animals to existing culverts/underpasses, and verge management to reduce prey/scavenging attractants) thereby improving road safety while maintaining functional seed-mediated connectivity.