Bats
Project Investigators
Joy O’Keefe, University of Illinois, (217) 300-6933, jmokeefe@illinois.edu
For many animals, like deer and turkey, scientists know how logging affects local populations. However, we know much less about the endangered Indiana bat (Myotis sodalis). Part of the issue is that these bats spend summers in dead or dying trees with loose bark. Female bats form large colonies in these snags, often with over 100 bats, to raise their young. Because of this, biologists worry that timber harvesting will remove key roost trees or the trees needed for future roosts.
Indiana bats use large trees with peeling bark and plenty of sunlight. Oaks and hickories work best because dead trees hold onto their bark for many years. Maples offer lower quality roosts and are rarely used. Meanwhile, no one has ever found an Indiana bat using a beech tree. As oak-hickory forests turn into beech-maple forests, they become less useful to bats. Logging is one way to reset forest growth. The main goal of the Hardwood Ecosystem Experiment is to learn how logging impacts wildlife.
We trap bats in two ways to study logging effects. First, we use mist-nets to catch bats as they fly through forest openings. This lets us handle the bats directly to check their age, sex, and health. However, nets only work well in funnel points like roads or streams. They do not catch bats flying high over the main forest.
To track those bats, we use Anabat® Detectors. These tools convert bat calls into digital files so we can identify species later. This method detects many more bats, but it does not give us detailed personal data on individual bats.
Key Papers:
- Bergeson, S.M., O’Keefe, J.M., and Haulton, G.S. 2018. Managed forests provide roosting opportunities for Indiana bats in south-central Indiana. Forest Ecology and Management, 427:305-316.
- Beilke, E.A., Haulton, G.S., and J.M. O’Keefe. 2023. Foliage-roosting eastern red bats select for features associated with management in a central hardwood forest, Forest Ecology, and Management, 527(1), https://doi.org/10.1016/j.foreco.2022.120604
- Beilke, E.A. and J.M. O’Keefe. 2022. Bats reduce insect density and defoliation in temperate forests: An exclusion experiment. Ecology. https://doi.org/10.1002/ecy.3903
- Bergeson, S.M., Confortin, K.A., Carter, T.C., Karsk, J.R., Haulton, S., Burnett, H. 2021. Northern long-eared bats roosting in a managed forest in south-central Indiana, Forest Ecology and Management, Volume 483,118928, https://doi.org/10.1016/j.foreco.2021.118928.
- Divoll, T.J., Aldrich, S.P., Haulton, G.S., and J.M. O’Keefe. 2022. Endangered Myotis bats forage in regeneration openings in a management forest. Forest Ecology and Management, 503 (1), Endangered Myotis bats forage in regeneration openings in a managed forest – ScienceDirect
Small Mammals
Project Investigator
Robert K. Swihart (Retired), Purdue University, (765) 494-3575, rswihart@purdue.edu
Elizabeth Flaherty, Purdue University, (765) 494-3567, eflaher@purdue.edu
Pat Zollner, Purdue University, (765) 496-9495, pzollner@purdue.edu
Small mammals play vital roles in forests as seed spreaders, seed eaters, and prey. The Hardwood Ecosystem Experiment studies how logging impacts these small animal groups. Dr. Robert Swihart set up live-trapping grids at 32 sites in 2007. Trapping occurs regularly to measure how small mammals respond to timber harvest. Researchers also measured habitat traits around each trap and across 900-acre management zones.
Results show that Eastern chipmunk numbers grew near harvest openings, rising 38% to 84% compared to unharvested sites. White-footed mice were unaffected by small openings, but their numbers dropped 32% in 10-acre openings. Short-tailed shrews increased slightly in 1-acre openings but declined in larger clearings. Other factors mattered as well. Mice and shrew populations were lower on sunny, southwestern slopes and after years with low acorn crops. Chipmunks and mice benefited from woody debris left after harvests. However, shrews avoided harvested areas that lacked thick leaf litter.
We are now studying how logging and prescribed fire affect small mammal survival and seed spreading. We tag captured mice, chipmunks, and pine voles before releasing them at the same site. We also use motion-activated cameras when live traps are inactive. Combining these two methods helps us test if non-invasive cameras can reliably monitor small mammals over time.
Key Papers:
- Kellner, K.F., N.A.Urban and R.K.Swihart. 2013. Short-term responses of small mammals to timber harvest in the Central Hardwoods. Journal of Wildlife Management, 77(8): 1650-1663.
- Kellner, K.F., N.I.Lichti and R.K.Swihart. 2016. Midstory removal reduces effectiveness of oak (Quercus) acorn dispersal by small mammals in the Central Hardwood Forest region. Forest Ecology and Management, 375:182-190.
- Kellner, K.F. and R.K.Swihart. 2014. Changes in small mammal microhabitat use following silvicultural disturbance. American Midland Naturalist, 172: 349-359.
- Nelson, D.L., Kellner, K.F., and Swihart, R.K. 2019. Rodent population density and survival respond to disturbance induced by timber harvest, Journal of Mammalogy 100(4):1253-1262.