Conducting behavioral observations on spiders and grasshoppers, circa 2007

Brandon Barton

Education

B.S. Wildlife Resources, University of Idaho, 2003

M.S. Biology, University of Central Florida, 2005

PhD Candidate, Forestry and Environmental Studies, Yale University, in progress

I am interested in the direct and indirect effects humans have on food webs within ecological communities. I currently pursue this interest by studying the effects of climate change on New England meadow communities as part of my dissertation research and also through an ongoing project examining intraguild predation among sea turtle predators in Florida.

Climate change in meadow communities

Much of the research that has been conducted on climate change in terrestrial systems has focused on vegetation, thus making the assumption that bottom-up processes are more important than top-down. However, in many systems, such as New England meadows, evidence suggests that top-down processes can have important effects on community dynamics. In the meadows where I work, grasshopper herbivores (Melanoplus femurrubrum) can drastically change the plant community by selectively foraging on a single, competitively dominant Goldenrod species (Solidago rugosa). Grasshoppers only forage on Goldenrod when exposed to predation risk by spiders (Pisaurina mira) because its dense canopy of leaves creates a refuge from predators. Thus, the spider is an indirect keystone species that has a diversity-enhancing effect on the plant community, mediated by a behavioral response by the grasshopper. My dissertation research aims to understand how increasing temperatures due to climate change may affect predator-prey interactions and, consequently, the community as a whole. I am addressing this question by conducting multi-year field experiments and behavioral observations of spider-grasshopper-plant food webs under simulated climate warming.

Leatherback sea turtle at Archie Carr National Wildlife Refuge, Florida

Intraguild predation on sea turtle nesting beaches

In Florida, raccoons (Procyon lotor) are removed from loggerhead (Caretta caretta) nesting beaches to decrease egg predation. However, raccoons are also predators of ghost crabs (Ocypode quadrata), and ghost crabs also consume a large number of loggerhead eggs annually. Research conducted for my Masters degree demonstrated that intraguild predation by raccoons limited ghost crab populations and that raccoon removal resulted in higher densities of ghost crabs. Areas where raccoons were not abundant because of trapping still had the highest rates of total egg predation because of dense ghost crab populations. I am currently collaborating with researchers at the University of Central Florida to answer a question that arose during this project: why was raccoon predation highest where raccoon abundance was lowest? We believe that raccoons can easily locate sea turtle nests that have been attacked by ghost crabs because chemical cues are transmitted through the ghost crabs burrow and to the beach surface. Thus, as ghost crab density increases following raccoon removal, any remaining raccoons will be more efficient at finding sea turtle nests by following ghost crabs to the eggs. We are also using a long-term dataset to further address the effects of raccoon and ghost crab predation on sea turtle conservation.

Peer-reviewed publications

Barton, B. T. and J. D. Roth (In review). Implications of intraguild predation for sea turtle nest protection.

Barton, B. T. and J. D. Roth (2007). Raccoon removal on sea turtle nesting beaches. Journal of Wildlife Management 71:1234-1237.

Schmitz, O. J., H. P. Jones and B. T. Barton (2007). Scavengers. Encyclopedia of Ecology. Elsevier, UK.