Basin‐Wide Effects of Game Harvest on Vertebrate Population Densities in Amazonian Forests: Implications for Animal‐Mediated Seed Dispersal

TLDR

Vertebrate responses to hunting vary widely among target and non‑target species, influenced by hunting history, site productivity, and species life‑history traits. The study conducts a comprehensive meta‑analysis of population density and abundance estimates for 30 mid‑sized to large mammals, birds, and reptiles across 101 hunted and non‑hunted Neotropical forest sites. The authors analyzed 1,811 abundance estimates within 25 geographic clusters, applying both unnested and nested pairwise comparisons of sites with similar habitat and soil conditions. Average nested abundance changes ranged from moderately positive to highly negative, with overall declines up to 74.8 % in heavily hunted sites; 22 of 30 species declined significantly at high hunting levels, and large‑bodied species and frugivores experienced the greatest reductions.

Abstract

ABSTRACT Vertebrate responses to hunting are widely variable for target and nontarget species depending on the history of hunting and productivity of any given site and the life history traits of game species. We provide a comprehensive meta‐analysis of changes in population density or other abundance estimates for 30 mid‐sized to large mammal, bird and reptile species in 101 hunted and nonhunted, but otherwise undisturbed, Neotropical forest sites. The data set was analyzed using both an unnested approach, based on population density estimates, and a nested approach in which pairwise comparisons of abundance metrics were restricted to geographic groups of sites sharing similar habitat and soil conditions. This resulted in 25 geographic clusters of sites within which 1811 population abundance estimates were compared across different levels of hunting pressure. Average nested changes in abundance across increasingly greater levels of hunting pressure ranged from moderately positive to highly negative. Populations of all species combined declined across greater differences in hunting pressure by up to 74.8 percent from their numeric abundance in less intensively hunted sites, but harvest‐sensitive species faired far worse. Of the 30 species examined, 22 declined significantly at high levels of hunting. Body size significantly affected the direction and magnitude of abundance changes, with large‐bodied species declining faster in overhunted sites. Frugivorous species showed more marked declines in abundance in heavily hunted sites than seed predators and browsers, regardless of the effects of body size. The implications of hunting for seed dispersal are discussed in terms of community dynamics in semi‐defaunated tropical forests.