Chronic wasting disease undermines efforts to control the spread of brucellosis in the Greater Yellowstone ecosystem

Authors: MALONEY, MATT - University Of Wyoming; MERKLE, JEROD - University Of Wyoming; AADLAND, DAVID - University Of Wyoming; Peck, Dannele; HORAN, RICHARD - Michigan State University; MONTEITH, KEVIN - University Of Wyoming; FINNOFF, DAVID - University Of Wyoming; SIMS, CHARLES - University Of Tennessee; SCHUMAKER, BRANT - University Of Wyoming

Submitted to: Ecological Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2020
Publication Date: 8/31/2020
Citation: Maloney, M., Merkle, J.A., Aadland, D., Peck, D.E., Horan, R.D., Monteith, K., Finnoff, D., Sims, C., Schumaker, B. 2020. Chronic wasting disease undermines efforts to control the spread of brucellosis in the Greater Yellowstone ecosystem. Ecological Applications. 30(6). Article e02129. https://doi.org/10.1002/eap.2129.
DOI: https://doi.org/10.1002/eap.2129

Interpretive Summary: Two animal diseases—chronic wasting disease and bovine brucellosis—threaten some of the Greater Yellowstone Ecosystem’s (GYE’s) most important economic sectors: elk hunting and cattle ranching. Brucellosis is currently found in elk of the GYE, and occasionally spreads to cattle in the region. Chronic wasting disease (CWD) is rapidly spreading in wild deer, moose and elk towards the GYE, where some wildlife stakeholders worry that the current practice of providing supplemental feed to elk during the winter at official feedgrounds may worsen the spread of CWD among elk. However, if feedgrounds are eliminated, some stakeholders worry it might increase the number of elk overwintering on private cattle ranches, thus increasing the risk of brucellosis spreading from elk to cattle. To evaluate the potential economic consequences of various elk-feedground management strategies when both CWD and brucellosis are present, we develop a biological and economic model that accounts for both space and time. GPS data from elk and landscape characteristics are used to simulate elk migration and population with and without supplementary feeding. As a case-study, we model an area around Pinedale, WY, that contains four existing elk feedgrounds. For this area, we simulate the economic impacts to elk hunting and cattle ranching of a variety of management strategies over a 100-year period. Our results indicate that continuing to feed elk could result in substantial economic losses in the case-study region. Therefore, to maximize economic net benefits generated by the local elk population, assuming CWD arrives in the region, wildlife managers may wish to consider the option of discontinuing elk feedgrounds, and explore creative ways to offset any negative financial impacts on ranchers of possible increases in brucellosis transmission to livestock. Our methods can be used, more generally, to weigh the costs and benefits of human-wildlife interactions in the presence of multiple diseases.

Technical Abstract: Wildlife diseases pose a substantial threat to the provisioning of ecosystem services. We use a novel modeling approach to study the potential loss of these services through the imminent introduction of chronic wasting disease (CWD) to elk populations in the Greater Yellowstone Ecosystem (GYE). A specific concern is that concentrating elk at feedgrounds may exacerbate the spread of CWD, whereas eliminating feedgrounds may increase the number of elk on private ranchlands and the transmission of a second disease, brucellosis, from elk to cattle. To evaluate the consequences of management strategies given the threat of two concurrent wildlife diseases, we develop a spatio-temporal bioeconomic model. GPS data from elk and landscape attributes are used to predict migratory behavior and population densities with and without supplementary feeding. We use a 4,800 km2 area around Pinedale, WY containing four existing feedgrounds as a case study. For this area, we simulate welfare estimates under a variety of management strategies. Our results indicate that continuing to feed elk could result in substantial welfare losses for the case-study region. Therefore, to maximize the present value of economic net benefits generated by the local elk population upon CWD’s arrival in the region, wildlife managers may wish to consider discontinuing elk feedgrounds while simultaneously developing new methods to mitigate the financial impact to ranchers of possible brucellosis transmission to livestock. More generally, our methods can be used to weigh the costs and benefits of human-wildlife interactions in the presence of multiple disease risks