Deer How movement disease and harvest influence mule deer vital rates in the Southeast Bighorn Basin Part of a larger problem Since 2010 33 Decline in the Paintrock Herd Unit 55 Decline in the Southwest Bighorns Herd Unit ID: 1043335
Download Presentation The PPT/PDF document "Chronic Wasting Disease and Declining Mu..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
1. Chronic Wasting Disease and Declining Mule DeerHow movement, disease, and harvest influence mule deer vital rates in the Southeast Bighorn Basin
2. Part of a larger problem…Since 2010:-33% Decline in the Paintrock Herd Unit -55% Decline in the Southwest Bighorns Herd UnitDeclining estimates correlate with a general lack of deer found during winter flights and during the October hunting seasons. Increasing CWD Prevalence amongst Sympatric Mule Deer and White-tailed Deer in the Paintrock Herd Unit
3. What do we suspect is changing? Long Term vs Short TermHabitat: The long term decline in abundance could be caused by habitat loss/degradation from the cumulative impacts of conifer encroachment, invasive species(sagebrush to cheatgrass conversion on winter range), and interspecific (amongst other ungulates) or intraspecific (amongst mule deer) competition.Disease:Recent increases to Chronic Wasting Disease prevalence correlate with population decline where adult mortality may be out-pacing juvenile recruitment and inhibiting herd growth.
4. What are the potential management (harvest) solutions?In accordance with the Wyoming Game and Fish Department CWD Management Plan several experimental management strategies include but are not limited to:‘The Department will develop and implement lethal removal strategies to reduce cervid densities around disease foci locations (“hot spots”). Hunter harvest is the preferred method for addressing disease foci.’Implemented in 2022 with General Season changes that allow an additional week of hunting limited to ½ mile within irrigated lands where known CWD hot-spots exist in the Paintrock Herd Unit.
5. What are the potential management (harvest) solutions?“Decreasing population densities through increased harvest pressure to reduce the frequency of contacts between social groups, increase removal of CWD positive animals (both male and female), and reduce the potential for dispersal of infected animals”Implemented in 2020 with the introduction of “any deer” seasons to allow the harvest of doe mule deerIncreased female harvest may impact overall herd health and productivity by reducing herbivory/competition on shrub and forb communities. Significant increases to WTD quotas and the extension of seasons to increase WTD harvest where they are known to share home ranges with mule deer.
6. What are the potential management (harvest) solutions?“Increase mature male harvest to lower CWD prevalence and transmission. This may include altering season timing (earlier or later) and length or increasing license issuance.”Implemented in 2022 with the introduction of late season licenses
7. BACI Study Design“Harvest management strategies will be implemented over a sufficient amount of time in conjunction with robust monitoring and surveillance (BACI design) to allow for rigorous evaluation of such actions. By implementing experimental harvest management strategies in select areas, the Department will foster the broader understanding of CWD management”In accordance with the Deparment’s management plan we will enhance our monitoring through continued intensive CWD surveillance and the GPS collaring of doe mule deer (n=100) to estimate:Annual SurvivalInterchange between neighboring herd unitsMortality attributable to CWDMortality attributable to Hunter-Harvest
8. Preliminary Data: 2022 Field SeasonInitial collars (n=38) were deployed in December of 2021 and detected cause specific mortality for 9% and 20% of the Paintrock and SW Bighorns sample populations respectively.
9.
10.
11.
12. Habitat Management Implications15 year history of ongoing conifer removal and aspen enhancement work 20 year history of ongoing cheatgrass treatmentsMore recent history of riparian improvement projects Initial GPS locations indicate deer selecting summer ranges in close proximity to riparian and mesic habitatsCollared deer will help inform future habitat improvement projects such as timber thinning, aspen/riparian enhancement, and herbicide application.
13. Plans for the 2022-23 winter season…Keep our local constituents and interested stakeholders informed of ongoing research and disease monitoringContinued efforts to collect CWD samples from hunter harvested deer and sympatric elk. Deploy (n=85) additional GPS collarsUse sightability methods with our aerial surveys to improve the accuracy of our population estimates