Impact of Enzootic Plague on a Population of Mexican Woodrats

Abstract

Photo 1: Our controlled study of plague utilized capture–recapture to estimate survival rates of Mexican woodrats (Neotoma mexicana) in four groups comprising all combinations of vaccination, vector control, and no treatment. Photo credit: D. Biggins. Photo 2: Our study area in the Colorado foothills had many woodrat nests in shrub patches (especially three-leaf sumac, Rhus trilobata, whose leaves turned orange in fall (foreground and right side of photograph). A few nests were in cavities of cottonwoods (Populus deltoides; center). Photo credit : D. Biggins. Photo 3: Mexican woodrats are industrious nest-builders. Panel A shows a large stick nest (~ 1 m high, estimated volume 510 liters, ranked 11th largest of 139 stick nests measured) in a hawthorn (Crataegus succulenta) and sumac shrub patch. Some nests were in rock crevices (B). Photo credit : D. Biggins (A) and S. Ramakrishnan (B). Photo 4: Woodrats also constructed nests by modifying abandoned magpie (Pica hudsonia) nests (panels A and B). We infused woodrat nests on treated plots with deltamethrin dust to control vector fleas. Photo credit: D. Biggins. Photo 5: We trapped woodrats in wire mesh traps (A) and handled them under isoflurane anesthesia to collect blood samples (B), comb fleas, and take measurements, and to vaccinate a subsample of them with an experimental plague vaccine. We combed one or more fleas from 51% of the woodrats on non-dusted plots compared to a flea prevalence of 5% on dusted plots. Photo credit: S. Ramakrishnan. These photographs illustrate the article “Enzootic plague reduces survival of Mexican woodrats (Neotoma mexicana) in Colorado” by Biggins, D. E. S. Ramakrishnan, T. E. Rocke, J. L. Williamson, and J. Wimsatt published in Ecosphere. https://doi.org/10.1002/ecs2.3371.