I have always been interested in understanding the effects that we humans have on our natural surroundings. Specifically, I want to know if patches of seemingly natural habitat (e.g. forest fragments) are affected by the surrounding human impacted matrix (e.g. cow pastures). I have conducted both my master's and doctoral dissertation work in southern Costa Rica, looking at "edge effects" on populations of small forest lizards (left) and frogs.

Conservation biologists have often postulated that the presence of open areas such as cow pastures would cause many abiotic (e.g. temperature, wind, solar radiation) and biotic changes in the adjacent forest patches, and possibly render an entire band of "edge habitat" inhospitable to certain indigenous species. I set out to collect some data to test this claim, at least for a few forest interior species from one part of the world.

For my doctoral work I have been using mark-recapture methods to estimate the rates of movement and survival of 2 species of Norops lizards and 3 species of Eleutherodactylus frogs along a pasture-to-forest interior gradient in three different sites near Las Cruces, Costa Rica. If there exist strong "negative" edge effects, one would expect either these species to be absent from the pastures and forest edges, or for their survival to be lower there. I also measured several different environmental factors (habitat, prey abundance, abiotic conditions, parasite abundance) to try and understand which factors in this novel landscape may correlate with the high/low survival of each species.

Finally, I also looked at the egg ecology of one species of lizard, Norops polylepis, along the pasture to forest gradient. I raised females in captivity, and placed their eggs out in the field along the gradient to test how the very different conditions in the pastures (dry, warmer) relative to forests would affect the survival and development time of these eggs to hatching.