Assessing Wildlife Responses to Changing Fire Regimes

In 2020, two of Colorado’s largest wildfires, the Cameron Peak and East Troublesome fires, burned in Rocky Mountain National Park (RMNP) and the surrounding region₆. The size and severity of these fires follow a broader trend in larger, more frequent, and more severe wildfires in Rocky Mountain forests and the Western United States_{3 4 8 11 13}. Increasing temperatures and drought conditions attributed to climate change are predicted to exacerbate these wildfire conditions₁₂.

Nighttime camera trap photo of a marten at a burned site in Rocky Mountain National Park.

Photo Courtesy of Leah McTigue

Wildfires are Drivers of Diversity

Wildfires are important in shaping ecosystems by promoting biodiversity, also known as pyrodiversity. For example, fire removes accumulated dead organic matter from the soil allowing for new vegetation growth₅. However, it is unclear what the consequences of record-breaking wildfires and changing fire regimes have on local wildlife communities. Plants and animals are often adapted to the historical fire regimes for an ecosystem, so dramatic changes in how fire interacts with the landscape may have negative impacts on wildlife _{6 10}. A variation of positive and negative wildfire effects on bats, birds and terrestrial mammals has been observed. For example, bats may abandon their roosts during a wildfire, however, the number of insects in a burned area may double, increasing food availability for bats _{1 2 7 9}.

Camera trap photo of a coyote in East Troublesome fire burned site.

Photo Courtesy of Leah McTigue

Understanding Wildfire Impacts on Wildlife

To better understand wildlife responses to changing fire regimes, researchers from Colorado State University and the USDA Forest Service Rocky Mountain Research Station are co-leading a research study looking at several wildfires that burned across Colorado and Wyoming in 2020. Researchers will conduct wildlife surveys at burned sites and nearby unburned reference sites using camera traps and acoustic recorders. These devices will collect visual and audio data collection of bats, birds, and terrestrial mammals within RMNP during summer and fall from May-October 2024 and 2025. The wildlife surveys will be used to assess the occupancy rates, as well as the biodiversity and species richness of bats, birds, and terrestrial mammals at the chosen locations. Occupancy relates to environmental factors, such as fire burn severity and vegetation composition. Significant differences in the number of different animals recorded at sites in burned and unburned areas could help researchers determine the influence of severe wildfires on wildlife. A resurvey of the locations at 5-10 year intervals could document ongoing impacts of wildfires and changing fire regimes on local wildlife. Information from this study could inform wildlife management practices or restoration efforts in areas impacted by wildfires.

Camera trap photo of a deer at a burned site in RMNP.

Photo Courtesy of Leah McTigue

Citations

1. Dickinson, M.B., M.J. Lacki, and D.R. Cox. (2009). Fire and the endangered Indiana bat. In Fire in eastern oak forests, ed. T.F. Hutchinson, 51–75. Carbondale: Southern Illinois University

2. Dickinson, M.B., J.C. Norris, A.S. Bova, R.L. Kremens, V. Young, and M.J. Lacki. (2010). Effects of wildland fire smoke on a tree-roosting bat: integrating a plume model, field measurements, and mammalian dose-response relationships. Canadian Journal of Forest Research 40 (11): 2187–2203. https://doi.org/10.113 9/X10-148.

3. Higuera, P. E., Shuman, B. N., & Wolf, K. D. (2021). Rocky Mountain subalpine forests now burning more than any time in recent millennia. Proceedings of the National Academy of Sciences, 118(25), e2103135118.

4. Jolly, W. M., Cochrane, M. A., Freeborn, P. H., Holden, Z. A., Brown, T. J., Williamson, G. J., & Bowman, D. M. (2015). Climate-induced variations in global wildfire danger from 1979 to 2013. Nature communications, 6(1), 7537.

5. National Geographic Society. (2023, October 19). The Ecological Benefits of Fire. National Geographic. Retrieved June 28, 2024, from https://education.nationalgeographic.org/resource/ecological-benefits-fire/

6. National Interagency Fire Center. (2020). National Fire News. Retrieved December 21, 2021, from https://www.nifc.gov/fire-information/nfn.

7. Nimmo, D. G., Carthey, A. J., Jolly, C. J., & Blumstein, D. T. (2021). Welcome to the Pyrocene: Animal survival in the age of megafire. Global Change Biology, 27(22), 5684-5693.

8. Perry, R.W. (2012). A review of fire effects on bats and bat habitats in the eastern oak region. In Proceedings of the 4th Fire in Eastern Oak Forests Conference, vol GTR-NRS-P-102, 170–191. Springfield: Northern Research Station.

9. Scasta, J. D., Weir, J. R., & Stambaugh, M. C. (2016). Droughts and wildfires in western US rangelands. Rangelands, 38(4), 197-203.

10. Snider, E.A., P.M. Cryan, and K.R. Wilson. (2013). Roost selection by western longeared myotis (Myotis evotis) in burned and unburned pinon–juniper woodlands of southwestern Colorado. Journal of Mammalogy 94 (3): 640– 649. https://doi.org/10.1644/11-MAMM-A-153.1.

11. Steel, Z. L., Miller, J. E., Ponisio, L. C., Tingley, M. W., Wilkin, K., Blakey, R., ... & Jones, G. (2023). A roadmap for pyrodiversity science. Journal of Biogeography, 51(2), 280-293. https://doi.org/10.1111/jbi.14745

12. Wasserman, T.N., & Mueller, S.E. (2023). Climate influences on future fire severity: a synthesis of climate-fire interactions and impacts on fire regimes, high-severity fire, and forests in the western United States. fire ecol 19, 43 (2023). https://doi.org/10.1186/s42408-023-00200-8

13. Westerling, A. L., Hidalgo, H. G., Cayan, D. R., & Swetnam, T. W. (2006). Warming and earlier spring increase western US forest wildfire activity. science, 313(5789), 940-943.