Dasyprocta punctata), a large and common rodent that I've written about before (see 16 February 2010). In terms of its ecology, the agouti is territorial and terrestrial, although it does like being near water. Chan Chich creek meanders only 100 or so meters from this camera location, so this agouti should feel right at home. Agoutis seem to run on tiptoes and are capable of fairly high jumps straight up when startled.
This is a July photo at Chan Chich Lodge, early in the morning, so the infra-red flash gave us a black-and-white image. There were quite a few images in this series, of which this was clearly the best. I've found that the image quality really goes down during the hot summer months -- when the temperatures and humidity are really high. It'll be interesting to see whether, come January, the image quality improves.