Do Reduced Parasite Loads Contribute to Higher Abundances of Deer Mice?

Jonathan working overtime in the lab

Parasites are known to harm their hosts as they derive benefit, but are they capable of influencing the density and dynamics of their host populations?  Deer mice (Peromyscus maniculatus) are known to increase in abundance 2-5 times after a fire, but explanations for this increase remained unknown.  WIU graduate student, Jonathan Vaughn recently completed a study to investigate whether parasite load may be a factor to explain increased abundance of deer mice in post-burned forest.  Jonathan conducted an exhaustive survey for all ectoparasites (fleas, ticks and lice) and endoparasites (i.e., nematodes and cestodes) of specimens collected from a burned and unburned area of forest in western Montana.  Although no significant difference was found between the endoparasites from the two areas, the mean abundance of ectoparasites was lower in burned forest than unburned forest, especially for fleas, which exhibited a 70% reduction.  It’s possible that the improved healthy condition of deer mice from burned forest results in increases in abundance relative to their more heavily parasitized brethren from the unburned forest.   This study was conducted in collaboration with Rafal Zwolak and Sylwia Dziemian of the Adam Mickiewicz University (Poland) and Elizabeth Crone of Harvard Forest, Harvard University and under the guidance and mentorship of Jonathan’s graduate advisor, Dr. Shawn Meagher.   Jonathan has recently graduated and accepted a position as adjunct faculty at the WIU School of Agriculture.

A female flea, Aetheca wagneri