Uncompahgre Plateau Elk Management Plan DATA ANALYSIS UNIT E-20 GAME MANAGEMENT UNITS 61 & 62 Wildlife Commission Approved January 2006 Bradley A. Banulis, Terrestrial Biologist Colorado Division of Wildlife Montrose Service Center 2300 S Townsend Avenue Montrose, CO 81401 UNCOMPAHGRE PLATEAU ELK MANAGEMENT PLAN TABLE OF CONTENTS EXECUTIVE SUMMARY ……………………………………………………………… 4 INTRODUCTION AND PURPOSE ……………………………………………………. 7 DESCRIPTION OF DAU E-20 Location …………………………………………………………………………... 8 Physiography …………………………………………………………………….. 8 Vegetation ………………………………………………………………………... 9 Climate …………………………………………………………………………… 9 Land Use Ownership ……………………………………………………………. 9 Development ………………………………………………………….. 9 Agriculture ……………………………………………………………. 10 Recreation …………………………………………………………….. 10 Mining ………………………………………………………………… 10 Timber Harvest ……………………………………………………….. 11 Uncompahgre Landscape Assessment …………………………………………. 11 HERD MANAGEMENT HISTORY Post-hunt Population Size ………………………………………………………. 12 Post-hunt Herd Composition …………………………………………………… 13 Harvest Factors Affecting Harvest ……………………………………………. 16 Harvest History ………………………………………………………. 16 Public versus Private Lands Harvest …………………………………. 18 Hunters Hunter Numbers ……………………………………………………… 19 Hunter Success ……………………………………………………….. 19 Preference Points ……………………………………………………... 21 Resident versus Nonresident Hunters ………………………………… 22 Economic Impact ……………………………………………………... 24 CURRENT HERD MANAGEMENT Current Population Objectives ………………………………………………… 25 Harvest Management Unit 61 versus Unit 62 Management …………………………………. 25 Regular Season Antlerless Licenses ………………………………….. 25 Private Land Only Licenses …………………………………………... 25 Late Seasons ………………………………………………………….. 26 Damage Hunts ………………………………………………………… 26 1 HABITAT RESOURCE Habitat Distribution Summer Range ………………………………………………………… 26 Winter Range ………………………………………………………….. 26 Habitat Condition and Capability Habitat Condition …………………………………………………….. 27 Habitat Capability ……………………………………………………. 29 Conflicts Elk Damage …………………………………………………………… 39 Elk Competition with Domestic Livestock …………………………… 30 Elk Competition with Deer …………………………………………… 31 ISSUES Issue Solicitation Process ……………………………………………………….. 31 Issue Identification ………………………………………………………………. 31 ALTERNATIVE DEVELOPMENT Post-hunt Population & Sex Ratio Objectives ………………………………… 32 Management Strategies …………………………………………………………. 32 Management Alternatives ………………………………………………………. 33 Alternative Projections ………………………………………………………….. 34 Results of the 1998 E-20 Public Input Questionnaire …………………………. 35 CDOW PREFERRED OBJECTIVES & MANAGEMENT ALTERNATIVE ……… 36 APPENDICES Appendix 1. Chronology of E-20 Elk Hunting Regulations …………………... 37 Appendix 2. Results of the 1998 E-20 Public Input Questionnaire ………….. 38 LIST OF TABLES Table 1. Human population in the 5 counties that comprise DAU E-20, 1960-2004 (source U.S. 9 Census Bureau). Table 2. E-20 elk harvested on public versus private lands, 2000. 18 Table 3. Preference points required for E-20 limited licenses, 1998-2005. 21 Table 4. First choice landowner preference applications and quotas for Unit 61 bull and 22 either-sex licenses, 1999-2002. Table 5. E-20 resident versus nonresident elk hunter numbers and elk harvest, 1997 hunting season. 22 Table 6. E-20 resident versus nonresident elk hunter numbers and elk harvest, 2000 hunting season. 23 Table 7. E-20 resident versus nonresident elk hunter numbers and elk harvest, 2001 hunting season. 23 Table 8. Percentages of resident (RES) versus nonresident (NON) E-20 hunters, harvest, and success 23 rates, 1997 and 2000-2001. Table 9. Percentage of Unit 61 bull and either-sex elk licenses (395 licenses/year) issued to residents 24 versus nonresidents, 1998-2002. Table 10. Land ownership of DAU E-20 elk winter range in square miles and percent. 27 Table 11. Elk harvest, hunters, and economic impact for DAU E-20, 1997-2001. Either- sex license 34 holders (e.g., either-sex archery hunters and either-sex PLO hunters) were assigned to bull or cow hunter categories in proportion to the harvest of bulls and cows by each group. Local expenditure does not include license sales. Table 12. Projected annual elk harvest, hunters, and economic impact to maintain a post-hunt 35 population of 9,000 elk with 10 different post-hunt, bull:cow ratios. Shaded rows 2 most closely approximate management alternatives (Mgmt Alt) discussed on pages 30-31. Local expenditure does not include license sales. Table 13. Distribution and return of E-20 public input questionnaires. 38 LIST OF FIGURES Figure 1. E-20 Posthunt population estimate. 4 Figure 2. E-20 Harvest 4 Figure 3. E-20 Posthunt bulls/100 cows 4 Figure 4. Management by objectives process used by the CDOW to manage big game populations on 7 a DAU basis. Figure 5. Location of DAU E-20, GMUs 61 & 62, in southwestern Colorado 8 Figure 6. DAU E-20 estimated post-hunt elk population, elk hunters, and elk harvest, 1957- 2004. 12 95% confidence intervals average 7% for elk harvest and 3% for hunters since 1995. Figure 7. DAU E-20 estimated post-hunt elk population, elk hunter numbers, bull harvest, cow 13 harvest, and elk hunters, 1980-2004. 95% confidence intervals average 10% for bull and cow harvests and 3% for hunter numbers. Figure 8. DAU E-20 post-hunt bulls per 100 cows observed during aerial counts, 1983-2004. 14 95% confidence intervals for E-20 are generally 25%. Figure 9. Unit 61 bull age structure observed during post-season counts, 1983-2004. 14 Ybull = yearling, 2Bull = 2- year old, >2Bull = 3 years and older. Figure 10. Unit 62 bull age structure observed during post-season counts, 1983-2004. 15 Ybull = yearling, 2Bull = 2- year old, >2Bull = 3 years and older. Figure 11. DAU E-20 post-hunt calves per 100 cows observed during aerial counts, 1983-2004. 15 95% confidence intervals for E-20 are generally 13%. Figure 12. DAU E-20 elk harvest, 1980-2004. 95% confidence intervals for E-20 average 10 % 16 for bulls and cows and 36% for calves. Figure 13. DAU E-20 limited elk licenses, 1981-2005. 17 Figure 14. DAU E-20 cow elk harvest rate, bull harvest rate, and legal bull harvest rate as 18 percentages of the prehunt cow population, bull population, and legal bull population, respectively, 1980-2004. Figure 15. DAU E-20 elk hunter numbers, 1980-2004. 95% confidence intervals for E-20 19 average 3%. Figure 16. DAU E-20 hunter success, 1980-2004. 20 Figure 17. DAU E-20 elk harvest per 100 recreation days, 1984-2004. 21 3 Posthunt Sex Ratio (Bulls/100Cows): Objective Posthunt Population: Objective Posthunt Population: Land Ownership: GMUs: Number 10000 12000 14000 2000 4000 6000 8000 Bulls/100 Cows Number 61 and 62 0 10.0 15.0 20.0 25.0 30.0 35.0 1000 1200 1400 1600 0.0 5.0 200 400 600 800 0 1980 1980 1980 1981 24% Private, 37% USFS, 38% BLM, 1% State 1981 1981 1982 1982 1982 1983 1983 1983 Posthunt Population Estimate Figure 1. E-20 Posthunt Population Estimate Observed 1984 1984 Bull Harvest Bull 1984 1985 Figure 3. E-20 Posthunt Bulls/100 Cows PosthuntBulls/100 3.E-20 Figure 1985 1985 1986 8,500-9,500 1986 1986 1987 DAU E-20(Uncompahgre) 1987 2.E-20Harvest Figure 1987 1988 1988 EXECUTIVE SUMMARY 1988 1989 1989 2004 Estimate 1989 1990 1990 1990 1991 16-20 1991 1991 1992 1992 2004 Observed Modeled 4 1992 1993 1993 1993 1994 1994 1994 1995 1995 1995 1996 9,700 1996 Antlerless Harvest 1996 1997 1997 18 1997 Population Objective 1998 1998 1998 1999 2004 Modeled 1999 1999 2000 2000 2000 2001 Objective 2001 2001 2002 2002 2002 2003 2003 22 2003 2004 2004 2004 2005 E-20 Background GMU 61 has been managed as a quality elk hunting unit with limited licenses and greatly reduced hunting pressure for antlered elk since 1983. In contrast, GMU 62 has been managed as an unlimited, over-the-counter (OTC) license unit for bull elk hunting and has been one of the most heavily hunted units in Colorado. GMU 62 accounts for over 90% of bull and either-sex hunters and over 70% of the bull harvest in the DAU. The current posthunt population objective of 3,050 elk was based on early population models that underestimated the population and is unrealistically low. The current, observed posthunt sex ratio objective of 30 bulls/100 cows is impossible to achieve under current management that allows unlimited bull hunting in GMU 62. From 1990-1999, the estimated posthunt elk population in E-20 was fairly stable and averaged approximately 9,500 elk (Fig. 1). In 2000, the estimated posthunt population began increasing rapidly and reached a record high of 11,800 in 2001. Cow harvest was increased considerably in 2003-2004 to reduce the population. The 2004 posthunt elk population in E-20 was estimated to be 9,700 elk. The average, observed posthunt sex ratio between 1986 (the first year the 4 point antler restriction was implemented) and 2004 was 18 bulls/100 cows (Fig 2). The observed posthunt sex ratio in 2004 was also 18 bulls/100 cows. Observed posthunt age ratios for E-20 averaged 43 calves/100 cows (range 32–57) between 1984 and 2004. The trend in calf:cow ratios in E-20 has generally been downward at a rate of 0.5 calves/100 cows per year possibly indicating density- dependent factors are acting on the population. In 2002, a draft E-20 DAU Plan was submitted to the Wildlife Commission for approval. The preferred management alternatives in this plan were to manage both GMUs as totally limited, quality units for elk with a posthunt population objective of 8,500-9,500 elk and a posthunt, observed sex ratio objective of 30 bulls/100 cows. This proposal was based on (1)