Bats
Project Investigators
Joy O’Keefe, University of Illinois, (217) 300-6933, jmokeefe@illinois.edu
For many species of wildlife, particularly game animals such as deer and turkey, we have enough scientific knowledge to predict the results of timber harvest on local populations. Such is not the case for the endangered Indiana bat (Myotis sodalis). Part of the problem is that these bats spend their summers in old dead or dying trees with loose bark. In these snags the females form large colonies (often with 100+ individuals) and raise their young. So biologists are very concerned that timber harvest will either remove the roost trees or the next generation of roost trees.
Although Indiana bats will use almost any large tree with sloughing bark and substantial solar exposure, oaks and hickories seem to be some of the better roosts because one dead tree will hold onto its bark for many years. Maples are rarely used and seem not to form high quality roosts, while no one has ever recorded an Indiana bat using a beech. Thus, we also face a situation that as oak-hickory forests become beech maple forests, they may become less valuable to bats. One way of turning back the clock on succession is by using timber harvest—the overall goal of Hardwoods Ecosystem Experiment is to determine the impact of harvest on a wide variety of wildlife.
To determine the impact of timber harvest on bats we are “trapping” bats in 2 ways. First, we are using mist-nets to capture them as they fly through an opening in the forest. This allows us to directly handle the bats and determine their age, sex, reproductive state, even if they have been captured before. Unfortunately, mist-nets are only effective when placed in an area, such as a roadway or stream, where bats are funneled into the net. Thus, they are not very good for detecting bats that are simply flying through, or over a forest. To “trap” these bats we are using a device called an Anabat® Detector that converts the echolocation calls of bats into an electronic file. Once these data are stored, we can go back and identify many of the calls to species. This technique allows us to “capture” many more bats, but we do not have the detailed information about the individuals such as we get from netting.
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 are important but seldom-seen components of forest ecosystems. They play important roles as seed dispersers, seed predators, and food for larger animals. The Hardwood Ecosystem Experiment is studying the effect of forest management on small mammal populations and communities. Dr. Robert Swihart designed a study in which livetrapping grids were established at 32 sites during summer of 2007, and trapping has been conducted regularly since then to determine short-term responses of small mammals to harvesting. Attributes of habitat also were measured around each trap, in the area scheduled for harvest, and in each of the 900-acre management units, to assess whether certain attributes are consistently associated with use by small mammals. Eastern chipmunk numbers increased with harvest opening size – abundance was 38% to 84% greater than in unharvested sites. White-footed mice were unaffected by small to medium-sized openings but declined by 32% in the largest 10-acre openings. Short-tailed shrews tended to increase slightly in association with 1-acre openings but declined slightly in larger openings. Other factors also influenced abundance: numbers were lower for shrews and mice on sites with southwestern aspects and following years of poor acorn production. Chipmunks and mice benefited from increased woody debris created by harvests, but shrews avoided harvest areas without a well-developed layer of leaf litter.
We currently are evaluating effects of timber harvest and prescribed fire on the survival of small mammals and on their behavior as seed dispersers. Additionally, all captured white-footed mice, chipmunks, and pine voles will be marked for individual identification and then released at site of capture. When grids are not actively live-trapped, we also will survey those sites using a passive camera trapping method designed for small mammals. The combination of these two data sets will allow us to evaluate the noninvasive camera method for future efforts monitoring small mammal responses to silviculture treatments 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.