Peter Guiden.

Assistant Professor of Biology Peter Guiden co-authored an article that was recently published online in the journal Ecology. In “Reintroduced megaherbivores indirectly shape small-mammal responses to moonlight,” Guiden and his fellow researchers described their study of the effect of moonlight on the activities of two nocturnal small mammal species.

Using live-trapping data collected in the Nachusa Grasslands over an eight-year period, researchers analyzed counts of deer mice and prairie voles trapped in field plots with and without bison in order to determine whether reintroduced megaherbivores (in this case, Bison bison) might indirectly alter moonlight avoidance by small mammals in tallgrass prairies.

They found that on nights without moonlight, deer mouse activity was similar, whether or not bison were present. Nights with peak moonlight showed four times greater deer mouse activity in plots without bison than in those with bison.

The study also showed that in plots with bison, prairie vole activity during full moons was twice what it was during new moons. By using temperature sensors to estimate when the voles entered the traps, the researchers determined that most of this activity occurred before moonrise or after moonset, rather than while the moonlight was brightest.

“We conclude that megaherbivores play an unappreciated but important indirect role in tallgrass prairies by inducing behavioral shifts in other animal species,” Guiden and his co-authors wrote. “Because overlap in activity patterns can predict the likelihood of predator–prey encounters, such activity shifts have important implications for trophic interactions throughout restored prairie food webs.”

The study was funded by Friends of Nachusa Grasslands and a grant from the National Science Foundation. The Nachusa Grasslands nature preserve, located in Franklin Grove, Ill., is managed by The Nature Conservancy.

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