Transboundary mammals in the Americas: Asymmetries in protection challenge climate change resilience

Aim Transboundary conservation is key to addressing poleward range shifts that will result from climate change. At a species level, transboundary coordination may be hindered by inter-country differences in protection of species. We explored how commonly mammal ranges in the Americas were transboundary, identified transboundary mammals whose poleward versus equatorial range limits fell in different countries and examined asymmetries in listing status of mammals. Location The Americas. Methods We intersected mammal ranges with country boundaries to identify transboundary species. We then determined the conservation status of mammals at the national level by compiling a database of all national-level listing status documents across the Americas and at the global level through use of the IUCN Red List database. Results Over 62% (1,114 species) of mammals were transboundary in any cardinal direction, and over 50% (850 species) had poleward and equatorial range limits in different countries. Of those 850, 26% experienced asymmetric listing, with one range limit designated at a higher listing status than the other at the national level. Mismatches between national and global listing also were apparent at equatorial and poleward range edges. These same general patterns held when our analyses were restricted to globally at-risk mammals. Main Conclusions Although listing status of a species does not necessarily equate to actual level of protection, these results demonstrate that formal listings of species vary substantially across country boundaries, and in particular at the latitudinal range extremes. Asymmetries in listing could indicate that species are under less threat in one country compared to another or could reflect different levels of concern in the two countries although population status is similar. Regardless, asymmetries in listing could challenge cross-border connectivity and climate change resilience in the face of species range shifts and indicate the need for greater transboundary coordination in species management.