Boom and bust cycles of black-tailed prairie dog populations in the Thunder Basin grassland ecosystem

Authors: DAVIDSON, A - Colorado State University; Augustine, David; JACOBSEN, H - Colorado State University; PELLATZ, D - Thunder Basin Grasslands Prairie Ecological Association; Porensky, Lauren; MCKEE, GWYN - Great Plains Livestock Consulting, Inc; DUCHARDT, COURTNEY - Oklahoma State University

Submitted to: Journal of Mammalogy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2022
Publication Date: 5/4/2022
Citation: Davidson, A., Augustine, D.J., Jacobsen, H., Pellatz, D., Porensky, L.M., McKee, G., Duchardt, C. 2022. Boom and bust cycles of black-tailed prairie dog populations in the Thunder Basin grassland ecosystem. Journal of Mammalogy. Article gyac035. https://doi.org/10.1093/jmammal/gyac035.
DOI: https://doi.org/10.1093/jmammal/gyac035

Interpretive Summary: In the western Great Plains, populations of black-tailed prairie dogs can increase dramatically over a series of years, and then suddenly collapse to very low levels due to an outbreak of epizootic plague caused by the bacterium Yersinia pestis. These dramatic population cycles also affect the many species that depend on prairie dog colonies for habitat and prey, as well local ranching communities that rely on grasslands for livestock production. Becasue these population fluctuations occur over a series of years (often on the order of one decade), few studies have quantified the magnitude, timing, spatial scale, and drivers of plague epizootics associated with prairie dog populations and colony dynamics over time. We studied black-tailed prairie dog colonies at Thunder Basin National Grassland, Wyoming over a period of 21 years. The colonies experienced three plague epizootics during our study, and consequently three boom-bust cycles. The entire prairie dog colony complex collapsed over a one-year period during the first and third epizootics and over a three-year period during the second epizootic. The boom-bust cycles were characterized by relatively rapid contractions in total area occupied by prairie dogs during a plague outbreak (up to 118-fold over 1 year) followed by much slower recovery times (up to 25-fold increase over 11 years). Prairie dogs occupied a total of 26,548 acres during at least one or more surveys within the study period, but much of the area was not consistently occupied over time. We found that each of the three plague outbreaks followed a dry year and occurred when prairie dog colonies where highly connected and there were higher temperatures and summer precipitation. Our results illustrate the cyclic and extreme nature of fluctuations in black-tailed prairie dog colony size and distribution in landscapes where plague occurs, and illuminate some of the drivers of these cycles. Further, our work shows how introduced diseases can dramatically influence populations of a keystone species, with important consequences for the broader ecological system.

Technical Abstract: Boom and bust population cycles occur in natural ecological systems, but increasingly they are driven by anthropogenic disturbances that destabilize wildlife populations and the ecosystems they inhabit. Black-tailed prairie dogs (Cynomys ludovicianus) exhibit boom-bust cycles in landscapes where they are affected by outbreaks of plague caused by the bacterium Yersinia pestis. These dramatic population cycles impact species that depend on large prairie dog colonies for habitat and prey, as well local ranching communities that rely on grasslands for livestock production. Few studies have quantified the magnitude, timing, spatial scale, and drivers of plague epizootics associated with prairie dog populations and colony dynamics over time. We examined spatiotemporal dynamics of black-tailed prairie dog colonies at Thunder Basin National Grassland, Wyoming over a period of 21 years. The colony complex experienced three plague epizootics during our study, and consequently three boom-bust cycles. The entire prairie dog colony complex collapsed over a one-year period during the first and third epizootics and over a three-year period during the second epizootic. The boom-bust cycles were characterized by relatively rapid contractions in total area occupied by prairie dogs during a plague outbreak (up to 118-fold over 1 year) followed by much slower recovery times (up to 25-fold increase over 11 years). Prairie dogs occupied a total of 10,712 ha during at least one or more surveys within the study period, but much of the area was not consistently occupied over time. We found that each of the three plague outbreaks followed a dry year and occurred when prairie dog colonies where highly connected and there were higher temperatures and summer precipitation. We were unable to detect a role of climate in driving colony growth, however. Our results illustrate the cyclic and extreme nature of fluctuations in black-tailed prairie dog colony size and distribution in landscapes where plague occurs and illuminate some of the drivers of these cycles. Further, our work shows how introduced diseases can dramatically influence populations of a keystone species, with important consequences for the broader ecological system.