Seed Dispersal and Density Compensation in Hunted Primate Communities

While large primates like spider monkeys and howler monkeys are hunted heavily in the Neotropics, small monkeys are generally ignored.  The result is a reshuffling of primate community structure, and the possibility for what is known as density compensation - when small primates increase in abundance and offset the decline of large primates.  Collaborator Varun Swamy and I have been conducting field work in the Madre de Dios region of Peru to understand the extent and consequences of these compensatory responses.

We conducted line transect surveys at three field sites across a gradient of hunting pressure: Reserva Amazónica (heavily hunted), the Los Amigos Biological Station (recovering from past hunting pressure) and the Tambopata Research Center (intact).  Using the program Distance, we estimated the abundance of several game and non-game animal species, including all primates.  We found that both small- and mid-sized primates exhibited population-level density compensation in response to the extirpation of large primates.  Small primate densities at the heavily hunted site reached five times their "natural" densities (take a look at the figure at right).  You can read more about this project in our paper here, and in a feature on the conservation news site Mongabay.com here.  Research on how these changes are affecting seed dispersal and forest regeneration dynamics is ongoing; for more info, see Varun's project website here.