Continental-scale local extinctions in mammal assemblages are synergistically induced by habitat loss and hunting pressure

Abstract

Understanding local-scale patterns of vertebrate species persistence or extirpation in the Anthropocene is a central challenge in conservation ecology. Based on real-world occurrences of 83 mammal ecospecies (i.e. strict ecological analogues often represented by parapatric congeners) across 1029 surveyed sites within the entire Neotropical realm, we set out to identify and disentangle the role of life-history traits under a phylogenetically controlled design in explaining local extinctions given the two leading threats to these species, namely habitat loss (the inverse of remaining habitat area [i.e. 100 – habitat area]) and hunting represented by a metric that ranged from −1.0 (non-hunted sites) to +1.0 (heavily hunted sites). We also examine the dominant role of body size in either reducing or aggravating local extinctions. We analyzed this large dataset using descriptive statistics, Generalized Linear Mixed Models, Phylogenetic Generalized Least Squares, and Phylogenetic Generalized Linear Mixed Models. Habitat loss was the leading driver of local extinctions affecting 75 % of all mammal species, whereas hunting exerted a coup de grâce effect on 70 % of the species whose local fates were determined by the synergistic interaction between habitat loss and hunting. Our results show that Neotropical sites across landscapes retaining ≤30 % of their original habitat and subjected to heavy levels of hunting pressure (≥0.40) contained only ~35 % of the historical mammal fauna. Even after the millennial timescale that shaped modern biotas, threats to the Neotropical megafauna have never been as severe as in the last five decades. Given the narrowing time window for mitigation action, it becomes imperative to implement conservation plans to effectively prevent or inhibit these leading threats to this vertebrate fauna.