Patterns of small mammal predation on different seeds in prairies
Prairies are one of our most diverse ecosystems and today less than one percent of native prairie remains. Prairies are important ecosystems because of their high biodiversity, potential to increase soil organic matter and store carbon. Due to the continued decline in prairie communities, many prairies are being planted on lands previously used for agriculture. Small mammals such as voles and mice have the potential to affect prairie plant communities during and after the restoration process by foraging on seeds and plants as communities mature. For example, seed predation can affect the survival and germination of seeds and alter the composition of seed pools when one species of seed is harvested more than another. In some prairies, small herbivores have been shown to fundamentally alter plant communities. We used cafeteria-style seed cards and incorporated camera traps in order to observe seed predators and determine seed preference in both a remnant and restored prairie in Southeastern Minnesota during the months of June and July. Live-trapping also provided information on the small mammal communities in both prairie types.
The small mammal community captured by the camera traps was quite different from those caught in live traps, with more large herbivores triggering cameras. Small mammals at both locations had similar seed preferences, with forb seeds being consumed more frequently than either legume or grass seeds. Although heavier or larger seeds with a higher energy content are often preferentially selected, we found a negative relationship between seed removal rate and seed weight. Despite different small mammal communities, four out of the five preferred seed species were the same on both remnant and restored prairies. Overall, stiff goldenrod was removed most quickly and western spiderwort was removed least often. Understanding the degree to which small mammals affect seed pools may highlight the ways these small herbivores affect the restoration of prairie plant communities.