Mule Deer and Elk Status Report for the San Juan/Chama Basin: Update

Transcription

1 Mule Deer and Elk Status Report for the San Juan/Chama Basin: Update Prepared for: Chama Peak Land Alliance Prepared by: Tom Watts Southwest Wildlife Services, LLC PO Box 2009 Pagosa Springs, CO

2 Introduction This report serves an as update to the November 2014 report prepared for the Chama Peak Land Alliance (CPLA) titled A Compilation of Mule Deer and Elk Population Data for the San Juan/Chama Basin. That reported analyzed population information for mule deer and elk from , and telemetry studies dating from the 1970 s to The purpose of this report was to update the last three years of data ( ) and provide a current assessment of elk and mule deer herds in the CPLA Project Area. Each year the four wildlife management agencies with jurisdiction over big game in this region conduct classification surveys and compile harvest statistics for mule deer and elk. In addition, several of the agencies initiated or continued telemetry studies to further define seasonal distribution and migration patterns for mule deer and elk within the region. One of the unique challenges faced by wildlife managers in the San Juan/Chama Basin is defining what constitutes the populations being managed separately by each jurisdiction. The use of multiple jurisdictions by individual deer and elk during different seasons has been well documented by all four management agencies. How to mesh the different management strategies to ensure the future health and productivity of these unique herds remains as elusive today as it was decades ago. Methods Project Area CPLA is 501c(3) non-profit conservation organization that is dedicated to good land, water and wildlife stewardship in the upper reaches of the San Juan and Chama River watersheds. The CPLA Project Area encompasses approximately 1.4 million acres of land straddling the New Mexico/Colorado Border (Figure 1). This area contains a mix of private, tribal, federal and state lands. The four agencies tasked with managing wildlife across this diverse landscape are the Colorado Parks and Wildlife (CPW), New Mexico Department of Game and Fish (NMDGF), Southern Ute Division of Wildlife Resource Management (SUDWRM), and the Jicarilla Game and Fish Department (JGFD). Figure 1 shows the areas managed by each agency in and around the CPLA Project Area, and Figure 2 shows the percentage of surface acres within each agencies jurisdiction. Colorado Mule deer and elk in CO are managed by CPW. CPW groups individual Game Management Units (GMU) into Data Analysis Units (DAU) for distinct deer and elk herds. Figure 1 shows the CO DAUs included in the CPLA Project Area. GMUs 75, 751, 771, 77 and 78 comprise elk DAU 31 (blue); while GMUs 80 and 81 comprise elk DAU 32 (green). These same groupings of GMUs are used for analyzing mule deer populations and are numbered deer DAU 30 (blue) and deer DAU 35 (green). 2

3 Southern Ute Indian Reservation Mule deer and elk on the Southern Ute Indian Reservation (SUIR) are managed by the SUWRMD. The SUIR encompasses approximately 680,000 acres, but is comprised of a checkerboard ownership pattern, with numerous private inholdings. The total acreage of tribal land, held in trust by the U.S. Government, is approximately 310,000 acres. The analysis of deer and elk herds on the reservation was commonly split between east side and west side segments, with the Animas River being the line of demarcation. However, for this report I used the reservation survey results as a single data set. New Mexico Mule deer and elk populations in New Mexico are managed by the NMDGF. The state is divided into separate GMUs for managing harvest, and into groupings of units for population data analysis. The NMDGF combines GMUs 4, 5B, 50, 51 and 52 into the north-central elk herd. Unit 5B is considered primarily winter range for the north-central elk herd. For this analysis I also included GMUs 2A, 2B, and 2C, which are considered primarily mule deer units, and have not been surveyed for elk since prior to Jicarilla Apache Reservation The Jicarilla Apache Reservation (JAR) encompasses approximately 890,000 acres, all held in trust by the U.S. Government. There are only 2 private inholdings, totaling less than 500 acres, and all lands owned by the Jicarilla Apache Tribe (JAT) are contiguous. Mule deer and elk are managed by the JGFD. The reservation is often split into north and south units for the purposes of hunting seasons and data analysis, but for this report I combined all the JAR information into a single data set. Population Statistics Population statistics included age and sex classification data derived from aerial surveys and harvest numbers. All 4 wildlife management agencies routinely gathered this type of information; however, there were some significant differences in how and when the data were collected. The CPW, SUWRMD and JGFD typically flew mule deer and elk classification surveys in late December or early January. These winter surveys sampled herds post-hunt and provided male:female ratios at their lowest level during the year. The NMDGF changed their elk survey techniques in 2008 and began flying the north-central elk herd surveys in late September. These fall surveys sampled the elk population prior to many of the rifle hunting seasons and produced pre-harvest estimates of bull:cow ratios. That pre-hunt data was then used to model the elk population and provide estimates of elk numbers and allowable harvest. 3

4 Figure 1. Map of the CLPA area showing Game Management Units and Indian Reservations. Surface Acres Managed by Each Jurisdiction Jicarilla - 10% Southern Ute 4% Colorado - 39% New Mexico - 47% CO NM JAR SUIR Figure 2. Proportion of the CPLA area managed by each of the four wildlife management agencies. 4

5 CPW and NMDGF provided estimates of deer and elk population size; however, the complexity of migration patterns and hunting seasons within the CPLA Project Area makes estimating these populations very difficult, if not impossible. Most estimates of total numbers come with a wide range of values and are based on untested assumptions. Additional information, such as age of animals harvested and scores of males harvested also was collected by several of the wildlife management agencies. The accumulation of telemetry studies in recent years, especially the GPS-based studies which provide very precise locations throughout the year, have highlighted the fact that herd boundaries used by management agencies in this region are somewhat arbitrary. Animals counted and classified during winter in one GMU, or jurisdiction, may have summered in a completely different area. The same is true for harvest data. Animals harvested in one GMU may have traveled miles from a totally different GMU, state, or jurisdiction. This report presents data from each of the four jurisdictions, and combined data across all jurisdictions to examine trends for the regional mule deer and elk herds. Hunter Harvest Hunter harvest was estimated differently in each of the 4 jurisdictions. CPW relied on a randomized telephone survey of hunters to estimate harvest of mule deer and elk in GMUs across the state. Their survey sampled approximately 20% of the licensed hunters statewide. The SUWD estimated hunter harvest on the SUIR from personal contacts with hunters when they pick-up their permits for the following season. This results in a sample size of approximately 75% of the hunters each year. The JGFD estimated hunter harvest from a combination of hunter questionnaires, mandatory check-in of animals, and personal contacts with local hunters to achieve sample sizes of %, depending on the hunt. NMDGF initiated mandatory harvest reporting for all elk and mule deer hunters in Hunters were required to file their harvest report on-line, by a set deadline date, or they were ineligible to apply for hunts the following year. Hunters who missed the deadline could pay an additional fee to file their harvest report to retain eligibility. This system produced consistently high sample sizes of hunters, often 90%+, for every hunt. 1. Telemetry Studies The 2014 CPLA report documented a number of telemetry studies conducted by all four wildlife management agencies. The overwhelming conclusion from those studies was that the majority of mule deer and elk migrated seasonally between higher elevation summer ranges and lower elevation winter ranges; although there was some variation depending on location within the project area. These migration routes frequently crossed state and tribal boundaries. The higher elevation habitats, above approximately 9500 ft., functioned almost exclusively as summer range; while many of the lower elevation areas harbored both resident and winter migrants of both species. Mule deer migration tended to be very predictable, based on calendar dates; while elk migration was influenced primarily by snow depth. Much of the fall migration occurred during the hunting seasons, and many animals were subjected to harvest across several jurisdictions during their journey to winter range. Animals birthed and grown in 5

6 one jurisdiction were often harvested in a different jurisdiction. Since all four management agencies have unique and vastly different harvest goals and strategies, balancing jurisdictional harvests to prevent over-harvest of elk and mule deer herds remains a challenge. Results Updated Telemetry Studies Jicarilla Game and Fish Department Elk The Jicarilla Game and Fish Department concluded a 2-year elk telemetry study in The final report (Seasonal Distributions and Migration Patterns of the Jicarilla Elk Herd, 2016) is available from Kyle Tator, JGFD, Dulce NM. Of the 28 elk (25 cows, 3 bulls) radio-collared, 52% were classified as migrants, 40% as non-migrating residents, and 8% as sedentary residents living off the reservation. Migrating elk moved to summer ranges north and east of the JAR. The average starting date for spring migrations was March 25, and migrations lasted 38 days. Average fall migrations started October 27 th and lasted 40 days. Elk migrating north from the JAR must cross US Highway 64/84. Spring highway crossings occurred from April 3-25 (average April 15 th ); but winter crossings occurred between November 8 and January 23 rd. This is consistent with other studies in the region, where elk winter migrations were more variable and weather dependent than spring migrations. Elk captured in the northern portion of the JAR exhibited migration patterns similar to those determined from earlier studies conducted by JFGD and CDOW (Figure 3). Unlike the earlier studies, elk were also captured in the southern portion of the JAR, and these elk displayed distribution and migration patterns previously unknown. Some of the southerncaptured elk migrated east to the Jemez Mountains, and some occupied new winter ranges on the JAR that have been colonized by elk in the last decade. These southern winter ranges harbored increased numbers of wintering elk and smaller numbers of resident, non-migratory elk. Although the study was not designed specifically to investigate elk mortality, 6 of the 25 cow elk died during the 2-year study. Four were harvested by hunters, 1 was killed by a mountain lion and 1 died of natural causes (old cow). Two were harvested in CO, one in NM, and one in the JAR. Elk migration routes encompassed several NM GMU s and several CO GMU s, highlighting once again the importance of multi-jurisdictional cooperation in managing the regional elk herd. The JAR supports a thriving resident elk herd, but also contains critical winter range for elk migrating from CO and NM. 6

7 Figure 3. Distribution of elk from GPS telemetry study conducted by the JGFD. 7

8 Mule Deer In January 2018 the JGFD captured 25 mule deer, from locations throughout the JAR, and equipped them with GPS collars. The last mule deer telemetry study on the JAR was in the late 1980 s, so this study will provide necessary updates to mule deer distribution and migration patterns. The earlier studies documented mule deer migrating primarily east-towest, and unlike elk, all collared mule deer stayed south of the CO/NM border. This new study will provide substantially greater precision in mapping mule deer distributions and migration routes. The collars are programmed to drop-off and the data will be retrieved in Southern Ute Wildlife Resources Management Department Elk The SUWRMD fitted 26 elk with GPS collars, and monitored them from All of the elk migrated from winter ranges on SUIR to summer ranges north of the reservation, primarily on US Forest Service lands (Figure 4). The study documented 46 individual spring migrations and 42 fall migrations (Table 1). Average start dates for elk migrations were April 18 th in the spring and October 25 th in the fall; very similar to dates from the JFGD study. The average duration of migrations were 46.4 days in the spring and 43.2 days in the fall. These were almost 30 days longer than mule deer migrations in the same area (determined from an earlier SUWRMD study). Average dates of arrival were May 26 th for summer range and December 7 th for winter range. Average distance between winter and summer ranges was approximately 60 miles. Annual survival rates for the collared cows ranged from 75-83%. Table 1. Duration of elk migrations from SUWRD, N(elk) n(migrations) Average Days SE 95% CI Spring Fall Colorado Parks and Wildlife Mule Deer CPW conducted a mule deer telemetry study from , focused on winter range areas from the Pine River to the Animas River, south and east of Durango, CO. Twenty-five adult does were fitted with GPS collars and monitored through November These deer migrated anywhere from 4 to 41 miles between summer and winter range, with an average distance of 23 miles. Spring migration started anywhere from April 8 th to June 1 st (average May 8

9 9th), exhibiting considerable variation compared to other studies. Spring migration averaged 11 days but ranged from 1-37 days in length. The initiation of fall migration averaged October 8th but ranged from September 22nd to October 30th. The average duration for fall migration was just 6 days (range 1-22 days). The winter range in this area is fairly developed and more populated than winter ranges from other recent studies in the CPLA area. There are numerous homes and small ranches scattered throughout this winter range, and deer have to cross many fences, ditches, roads and highways along their migratory route. They also migrated shorter distances between seasonal ranges than mule deer from the recent SUWRMD study. Figure 4. Distribution of migration of elk radio-collared by the SUWRMD, Elk In 2012 CDOW initiated an elk telemetry study along the Continental Divide east of Pagosa Springs. The study was scheduled to conclude in 2017; however, no data or reports were available at the time this report was completed. 9

10 New Mexico Department of Game and Fish The Rosa Mule Deer study, outlined in the original CPLA report, documented mule deer migration between the winter range in NM s GMU2 and summer ranges in southern CO. Phase 1 ( ) of the study documented baseline mule deer distribution and migration patterns prior to proposed energy development. Phase 2 was designed to monitor mule deer distribution and migration during development activities; however, that study was suspended due to a lack of development activity and cessation of funding. GPS collars were deployed on mule deer in anticipation of Phase 2, and those collars are scheduled to fall-off in April A final report on those mule deer will be available in September 2018 (Hall Sawyer, personal communication, 2018). Phase 1 determined that 100% of the collared deer were migratory, moving from winter ranges in northern NM (Unit 2) to summer ranges in the San Juan Mountains in CO. The Rosa mule deer did not actively avoid well pads, partly because of the high density of well pads on that winter range, and partly because the pinyon-juniper woodland habitat provided hiding cover in close proximity to well pads. Annual survival rates for the doe deer were 0.85 and 0.79, for 2012 and 2013, respectively. The average 0.79 annual survival rate was considered below average. Population Statistics: Mule Deer and Elk Population statistics used to define and manage big game populations include age and sex ratios, age structure of harvested animals, harvest levels, trend counts and population estimates. The initial CPLA examined data from This compilation of data on mule deer and elk populations spans Mule Deer Age and Sex Ratios Age and sex ratios are derived from aerial classification surveys flown in December/January. Although there are slight differences in how mule deer are classified by each agency the animals are recorded as does, fawns, immature or yearling bucks, and mature bucks. Classification of mature bucks differs slightly among agencies and is generally determined by the number of antler points, antler size and mass, and general appearance of the animal. The mature buck designation is more subjective than the other classification categories. The age:sex ratios derived from these counts are fawns:100 does, which is a measure of herd productivity and recruitment; and bucks:100 does, which is reflection of hunting harvest and trophy potential of a population. Classification surveys flown in early January are a reflection of the population during the preceding year. For example, the survey results listed for the year 2016 were derived from surveys flown in January

11 Colorado Tables 2 and 3 show the results of aerial classification surveys for in DAU 30 (west of the Continental Divide) and DAU 35 (east of the Continental Divide) Table 2. Summary of mule deer aerial surveys in DAU 30, Year DAU Buck:Doe MB:Doe Fawn:Doe Total Deer na Average Table 3. Summary of mule deer surveys in DAU 35, Year DAU Buck:Doe MB:Doe Fawn:Doe Total Deer No Flight No Flight No Flight No Flight No Flight Average

12 The addition of three years of new data did not appreciably change the average ratios for DAU 30. The deer herd in DAU 30 averaged 33 bucks, 10 mature bucks and 51 fawns per 100 does. All three ratios have been fairly stable over the past 10 years, with no significant decreases or increases. The mule deer in DAU 35 represent a distinct and separate deer herd from those in DAU 30, as indicated by the ratios. The average buck:doe ratio of 23:100 in DAU 35 is substantially lower than the 33:100 in DAU 30. More significantly, the average fawn:doe ratio of 41:100 in DAU 35 is 20% lower than the average ratio of 51:100 in DAU 30 and is well below what is needed to maintain a stable population. The 766 deer counted in DAU 35 in 2016 was the second lowest count recorded. Southern Ute Indian Reservation Table 4 summarizes mule deer surveys from the SUIR from The average buck:doe and fawn:doe from the SUIR are very similar to those from DAU 30. The overlap in mule deer distribution between DAU 30 and SUIR is significant, and it s no surprise that mule deer wintering in each jurisdiction exhibited similar age:sex ratios. The only difference was the somewhat higher mature buck:doe ratio found in the SUIR (17:100 vs 10:100), which reflected the more conservative mule deer harvest on the SUIR. Fawn:doe ratios on the SUIR declined in 2015 and 2016 and were below the average of 49:100. Table 4. Summary of mule deer surveys in the SUIR, Year Buck:Doe M Buck:Doe Fawn:Doe Total Deer Average

13 New Mexico Department of Game and Fish Table 5 shows the results of mule deer classification surveys for the combined GMU s 2,4,5A and 5B. These GMU s encompass most of the mule deer wintering areas within the CPLA area; however, not all units were surveyed every year. From survey procedures were changed from a generalized survey designed to count the maximum number of animals, to a stratified random sample of quadrants within each GMU. This shift in technique resulted in a significant decline in total number of deer classified during those years. The average ratios of 27 bucks, 17 mature bucks and 50 fawns per 100 does is strikingly similar to averages from both CPW and SUIR. This illustrates how interconnected these migratory mule deer herds are across jurisdictional boundaries. Table 5. Summary of mule deer aerial classification surveys in GMU s 2,4,5A and 5B, These units comprise most of the mule deer winter ranges in the CPLA area. Year Buck:100 Does MB:100 does Fawn:100Does Total Deer Average Jicarilla Apache Reservation Table 6 summarizes mule deer aerial classification surveys on the JAR from The average buck:doe ratio of 42:100, and mature buck:doe ratio of 21:100 reflected the JGFD s emphasis on trophy mule deer management. The very conservative mule deer harvest allows more bucks to survive each hunting season and advance into the mature age category. The average fawn:doe ratio of 52:100 was comparable to NM, CO -DAU 30, and SUIR. 13

14 Table 6. Summary of mule deer aerial classification surveys on the JAR, Year Buck:Doe MB:Doe Fawn:Doe Total Deer Average Combined Jurisdictions Table 7 summarizes the combined mule deer survey data from all four jurisdictions from Figure 5 shows the trend in total number of mule deer counted. Total number of deer counted declined steadily 10,707 deer in 2009, to 6287 deer in However, survey counts are not a reliable indicator of actual deer numbers. There are many variables that influence how many mule deer are counted during surveys, including flight budgets, flying time, snow cover, observer experience, and consistency in areas surveyed. The number of mule deer counted per flight hour is also not a reliable indicator of deer abundance. When survey funding is reduced, biologists focus on high density areas to count the maximum number of animals, which increases the number of deer counted/hour. Despite these caveats, an almost 50% decline in the number of mule deer counted between 2006 and 2016 was worth noting. Figure 6 shows the average proportion of mule deer counted on the four wildlife management jurisdictions from The two tribes accounted for 60% of the average number of mule deer counted. Both the SUIR and JAR contain extensive mule deer winter ranges, which probably accounts for the high numbers. Colorado accounted for 29% of the average total deer counted, and NM only 11%. Much of the CO portion of the CPLA area is strictly summer range, which does not have any mule deer in it during the winter surveys. Recent changes in the NMDGF survey techniques for mule deer, and infrequent surveys in some GMU s may have contributed to their low numbers. 14

15 Table 7. Summary of mule deer surveys, , all jurisdictions combined. Year Bucks Does Fawns Total Buck:Doe Fawn:Doe M Buck:Doe Average Total Mule Deer Surveyed -All Jurisdictions Figure 5. Trend in total number of mule deer counted during aerial classification surveys. 15

16 Average Proportion of Mule Deer Counted, Jicarilla-34% Southern Ute- 26% New Mexico - 11% Colorado- 29% SUWRD CPW NMDGF JGFD Figure 6. Distribution of mule deer counted during aerial classification surveys. Figure 7 shows the trend in fawn:doe and buck:doe ratios over the past 10 years. Except for a few low ratios in 2008 and 2009, the fawn:doe ratio has been either just above or just below 50:100 during most years and has averaged 49:100. That level is thought to be insufficient to grow a mule deer population (Gill 1999); and fawn:doe ratios in the 55-60:100 are generally required for an increasing population. For this combined data set, the peak fawn:doe ratio of 55:100 was achieved only once (2014) in the past 11 years. The buck:doe ratio reached its lowest point in 2012, at 26:100, but has increased to 35-37:100 for the past 3 years. This was a very positive trend in the buck:doe ratio, which should be reflected in increased harvest and higher success rates. Figure 8 shows the trend in the mature buck:doe ratio and the total number of mature bucks observed during classification surveys. The mature buck:doe ratio declined from 20:100 in 2008 to 12:100 in After that the ratio increased steadily, reaching 17:100 in The total number of mature bucks counted also increased between 2012 and 2016 (from 601 to 663), despite a 27% drop in the total number of mule deer classified. The increases in total mature bucks counted and the mature buck:doe ratio suggest a more conservative buck harvest region-wide, and a greater recruitment of bucks into the older age classes. 16

17 Trends in Fawn:Doe and Buck:Doe Ratios Fawn:100 Does Buck:Doe Figure 7. Trends in fawn:doe and buck:doe ratios, all jurisdictions combined. Trends in Mature Bucks Total Mature Bucks Mature Buck:Doe Number of Mature Bucks Mature Bucks:100 does 0 Figure 8. Trends in the number of mature bucks and mature buck:doe ratio. 0 17

18 Harvest and Hunter Success Buck Harvest Table 8. summarizes mule deer buck harvest from all four jurisdictions. Buck harvest started increasing in 2012, in both CO and NM, and reached an 11-year high combined harvest of 4,100 bucks in 2016 (Figure 9). This increased buck harvest coincided with an increase in the post-hunt buck:doe ratio, and an increase in total buck numbers observed during post-hunt surveys. So, despite declines in the total number of deer counted during surveys, and the subpar fawn:doe ratios, the mule deer herd seemed to be doing well, supporting record harvest while recruiting more bucks into the mature age class. Table 8. Summary of mule deer buck harvest by jurisdiction, Year So. Ute NMDGF Jicarilla Total Average Figure 9 shows the average proportion of mule deer bucks that were harvested on the four management jurisdictions from The SUIT and JAT accounted for only 8% of the average total buck harvest; while CO and NM accounted for 51% and 49%, respectively. 18

19 Annual Mule Deer Buck Harvest Colorado New Mexico Total Figure 8. Trend in annual buck harvest in CO and NM portions of the CPLA area. Percent of Average Annual Mule Deer Buck Harvest, Jicarilla 5% Southern Ute 3% New Mexico 41% Colorado 51% Southern Ute CO NM Jicarilla Figure 9. Distribution of average annual buck harvest,

20 Doe Harvest Table 9 shows the annual doe harvest within the CPLA area. The two jurisdictions that harvested does were the SUIR and CPW. Annual doe harvest has been declining since 2008, and the 2016 harvest was the lowest since 2006 (Figure 10). Table 9. Annual doe mule deer harvest in CO portion of CPOLA area. Year CPW So. Ute Colo Total Average Hunter Numbers Table 10 shows the number of mule deer hunters by jurisdiction from Total combined deer hunter numbers have trended downward since 2006 but increased significantly in 2016 (Figure 11). That increase was due solely due to a significant increase in mule deer hunters in CO, primarily in DAU 30. However, the total number of mule deer hunters in 2016 (8,142) was just slightly above the 11-year average of 8,034. Hunter Success Rates Table 11 shows the annual mule deer hunter success rates by jurisdiction. Both CO and NM averaged a 43% hunter success rate for Success rates for the two tribes were considerably higher, 76% for the JAR and 62% for the SUIR, due to lower hunter densities, longer seasons, and possibly higher mule deer numbers. 20

21 600 Annual Doe Harvest 500 Annual Doe Mule Deer Harvest Year Figure 10. Trend in annual doe mule deer harvest by SUWRMD and CPW, Table 10. Number of mule deer hunters by jurisdiction, Year CO NM Jicarilla So. Ute* Total Average *Approximate number of mule deer licenses issued. 21

22 Number of Combined Mule Deer Hunters Figure 11. Trend in the number of mule deer hunters for the combined jurisdictions. Table 11. Annual mule deer hunter success rates, by jurisdiction and combined, Year CO NM Jicarilla So Ute Total Average Figure 12 shows the trend in mule deer hunter success from Overall hunter success bottomed out in 2010 at 35% but has increased steadily since then. Hunter success peaked in 2015 at 55%, the dropped to 50% in This positive trend in mule deer hunter success rates was another indication the regional mule deer herd was doing well. 22

23 60 55 Mule Deer Hunter Success Rates-Combined Jurisdictions % Success Linear (% Success) 50 Mule Deer Hunter Success Figure 12. Mule deer hunter success rates for all jurisdictions combined. Population Estimates and Status Estimating mule deer numbers in this migratory population is an exercise fraught with so much error and speculation that any numbers generated are meaningless. Mule deer may summer in one jurisdiction but get counted in another during winter; and they be harvested in one of several jurisdictions during fall migration. Methods used to generate population numbers assume a closed population, with no ingress or egress. Those assumptions were not valid in any of the 4 jurisdictions; therefore, estimates of mule deer population size based on a single jurisdiction were inherently biased and not very useful for assessing population status or trend. Instead, the mule deer herd s status and trend can be inferred from the various population statistics monitored by the four management agencies. When the data from all 4 agencies was combined the following trends became clear: The number of mule deer being counted in aerial classifications has declined in recent years; however this may have been due to declining survey budgets as much as anything else and cannot be construed as a decline in deer numbers. The fawn:doe ratio, although not great, has been trending upward in recent years. The buck:doe and mature buck:doe ratios have both been increasing in recent years, despite increased buck harvest. Buck harvest increased by approximately 25% from

24 The number of mule deer hunters has been decreasing, yet hunter success rates have increased significantly since Although there is room for improvement in the fawn:doe ratio, all other population parameters point toward a robust mule deer herd capable of supporting the increased buck harvest, while still maintaining a good buck:doe ratio and increased mature buck:doe ratio. ELK Age and Sex Ratios Colorado Tables 12 summarizes elk classification survey data for DAU s E-31. DAU E-31 includes GMU s west of the Continental Divide (75, 751, 771, 77, 78). The calf:cow ratio in E-31 averaged 35:100 but exhibited a strong downward trend (Figure 13). Table 12. Summary of elk classification surveys in E-31, Year DAU Bull:Cow MB:Cow Calf:Cow Total Elk Average

25 Calf:Cow Ratio E Figure 13. Trend in calf:cow ratio in CO s E-31, The average bull:cow ratio in E-31 was 14:100, and the average mature bull:cow ratio was 2:100. Both ratios were relatively stable and showed only slight downward trends (Figure 14). E-31 posted the lowest mature bull:cow ratio among the four jurisdictions in the CPLA area. Bull:Cow Ratios E-31 Bull:Cow MB:Cow Linear (Bull:Cow) Linear (MB:Cow) Figure 14. trends in bull:cow and mature bull:cow ratios in E-31,

26 Table 13. summarizes elk classification surveys in E-32 from On average there were approximately one-third as many elk counted in E-32 as in E-31. The bull:cow and mature bull:cow ratios averaged 22:100 and 7:100, both considerably higher than ratios in E-31; however, both appeared to be trending downward (Figure 15). The calf:cow ratio in E-32 averaged 30:100 and had been trending downward until 2016 (Figure 16). In 2016 the calf:cow ratio jumped to 41:100, the highest ratio recorded in 11 years. Table 13. Summary of elk classification surveys in DAU E-32, Year DAU Bull:Cow MB:Cow Calf:Cow Total Elk Average Southern Ute Indian Reservation Table 14 summarizes elk classification data for the SUIR, from The calf:cow ratio averaged 36:100; similar to the 35:100 from E-31. The calf: cow ratio from the SUIR did not trend as strongly downward as in E-31; however, the ratios in 2015 and 2016 were among the lowest recorded since 2006 (Figure 17). The bull:cow and mature bull:cow ratios on the SUIR averaged 20:100 and 6:100, which were higher than ratios in E-31, most likely due to the more restrictive bull harvest on the SUIR. However, both ratios on the SUIR showed a downward trend (Figure 18), consistent with trends in E-31. Telemetry studies have documented extensive migration between E-31 and SUIR, and it s not surprising their respective classification surveys produce similar age:sex ratios. 26

27 Trend in Bull Cow Ratios: E-32 Bull:Cow MB:Cow Linear (Bull:Cow) Linear (MB:Cow) Figure 15. Trends in bull:cow ratios, DAU E-32, Calf:cow ratio in E Figure 16. Trend in calf:cow ratio, DAU E-32,

28 Table 14. Summary of elk classification data for the SUIR, Year Bull:Cow M Bull:Cow Calf:Cow Total Elk Average Trend in Calf:Cow Ratio - SUIR Figure 17. Trend in calf:cow ratio on the SUIR,

29 Trends in Bull:Cow Ratios-SUIR 30 Bull:Cow Linear (Bull:Cow) M Bull:Cow Linear (M Bull:Cow) Figure 18. Trend in bull:cow ratios, SUIR, New Mexico Table 15 summarizes elk classification for the NM portion of the CPLA area, which includes the north-central herd. Elk surveys were not flown in all GMU s every year. Figure 19 shows the trend in the NM calf:cow ratio, and contrary to the CO and SUIR surveys, the NM data exhibits a slightly increasing trend, especially since The NM average calf:cow ratio of 40:100 was also higher than the CO and SUIR ratios. However, the NM surveys were flown in September, so comparisons with the CO and SUIR surveys flown in December/January may not be relevant. The earlier NM surveys may be biased toward higher calf:cow ratios since they do not account for calf mortality that may have occured from September-December. The bull:cow ratio in NM averaged 39:100 and was relatively stable from (Figure 20). This ratio seems considerably higher than the other jurisdictions; however, NMDGF classification surveys are flown before the majority of bull harvest has occurred. Aside from the peak ratio of 59:100 in 2007, the NM bull:cow ratio has been relatively stable. It does not exhibit the strong downward trends observed in CO and SUIR. 29

30 Table 15. Summary of elk classification surveys for the NM GMU s in the CPLA area. Year Bull:Cow Calf:Cow Total Elk Average Calf:Cow Ratio in NM Figure 19. Trend in calf:cow ratio in the NM GMU s the CPLA area,

31 70 Bull:Cow Ratio in NM Bull:Cow Linear (Bull:Cow) Figure 20. Trend in bull:cow ratio in NM, Jicarilla Apache Reservation Table 16 summarizes elk classification surveys on the JAR from The bull:cow ratio averaged 33:100 and the mature bull:cow ratio averaged 13:100. There were no clear long-term trends in either ratio (Figure 21), but both ratios have increased since These were the highest post-hunt ratios among the four jurisdictions and were reflective of the JAR s conservative harvest and emphasis on trophy elk management. Table 16. Summary of elk classification surveys on the JAR, Year Bull:Cow M Bull:Cow Calf:Cow Total elk Average

32 Bull:Cow Ratios on the JAR Bull:Cow Linear (Bull:Cow) Mature Bull:Cow Linear (Mature Bull:Cow) Figure 21. Trends in bull:cow and mature bull:cow ratios on the JAR, The JAR calf:cow ratio averaged 43:100, which was slightly higher than the other post-hunt surveys but showed a similar downward trend (Figure 23). The calf:cow ratio increased in 2015 and 2016, very similar to the NM calf:cow ratio. 60 Calf:Cow Ratio on the JAR Figure 22. Trend in calf:cow ratio on the JAR,

33 Combined Jurisdictions Table 17 shows the total number of elk surveyed by the 4 wildlife management agencies from The data was summarized by state. The CO total is a combination of elk surveyed in E-31, E-32 and the SUIR. The NM total is a combination of elk surveyed in the NM north-central GMU s and JAR. There is no discernable long-term trend in total elk surveyed (Figure 23); however, counts in both states increased sharply in 2016, and the 16,423 elk counted in 2016 was the highest number recorded in the past 11 years. Table 17. Total elk surveyed in the CPLA area, Year Colo Total NM Total Grand Total The most notable pattern in Figure 23 was how the total numbers counted in NM and CO follow the same pattern of annual increases and decreases. A common misconception about the regional elk herd is that most of the elk spend the summer in the San Juan Mountains in CO and then migrate to winter ranges in NM. If that were the case, then in years experiencing heavy snowfall, more elk would leave CO to winter in NM; and elk counts would decrease in CO but increase in NM. However; Figure 23 shows that the annual trends in elk counts were very similar in the 2 states. In years where the counts decreased in CO, they also decreased in NM. In years where counts increased in CO, they also increased in NM. This illustrates that elk counts in NM were not inversely related to counts in CO. It also suggested that survey conditions and elk sightability probably have more influence on the total number of elk counted than elk migration across the state boundary. 33

34 Total Elk Classified Colo Total NM Total Grand Total Linear (Colo Total) Linear (NM Total) Linear (Grand Total) Figure 23. Total elk classified in CO and NM, Table 18 summarizes the age:sex ratios for the combined surveys from The 11-year averages for the combined herd were 24 bulls:100 cows and 37 calves:100 cows. Figure 24 shows the trend in bull:cow ratios for CO and NM and the combined data set. The bull:cow ratios for NM were considerably higher than for CO, due in part to the pre-hunt data from the NMDGF surveys and the conservative bull harvest on the JAR. There was a slight downward trend in the bull:cow ratio for all data sets; however, the NM ratio increased sharply from 30:100 in 2013 to 38:100 in 2014 and 41:100 in 2015 and This was close to the highest NM bull:cow ratio of 44:100 recorded in Figure 25 shows the trend in calf:cow ratios for CO, NM and the combined data. The declining trend in calf:cow ratios over the 11-year span is readily evident in the combined data set. The combined calf:cow ratio declined for 6 straight years, from 44:100 in 2009, to 30:100 in The calf:cow ratio then increased to 35:100 in These declining calf:cow ratios are a warning sign that something has changed in this regional elk population that historically posted calf:cow ratios of 45-50:100. Calf recruitment is the primary driver of elk population growth, and these declining rates reflected an elk population that has stopped growing and may be in decline. 34

35 Table 18. Age:sex ratios for the combined jurisdictions, Year Total # Elk Bull:Cow Calf:Cow Average Trends in Bull:Cow ratios CO NM Combined Linear (CO) Linear (NM) Linear (Combined) Figure 24. Trend in bull:cow ratios,

36 The NMDGF conducted an intensive calf mortality in northern NM and determined that black bear predation was severely limiting calf recruitment and herd productivity (Quintana 2016). Increased black bear harvest resulted in improved calf survival and herd productivity. Three additional NMDGF studies have also implicated predation as the primary cause of elk calf mortality and decreased recruitment rates. No calf survival/mortality studies have been conducted in the CPLA area to date. Trend in Calf:Cow Ratios 55 CO NM Combined Linear (Combined) Figure 25. Trend in cow:calf ratios for CO, NM and combined, Elk Harvest and Hunter Success Colorado Table 19 summarizes elk harvest and hunter success in CO s E-31 and E-32 (combined) from Figure 26 shows the trend in elk harvest levels in E-31 and E-32. Bull elk harvest from the 2 DAU s averaged 1839 bulls/year and exhibited a slight downward trend. The 1590 bulls harvested in 2016 was the second lowest during the past 11 years. Cow elk harvest declined significantly from a high of 2672 cows in 2007, to 757 cows in Cow harvest was relatively stable from The long-term trend for total elk harvest in E-31 and E-32 was sharply downward (Figure 26). Total elk harvest in E-31 and E-32 declined by 51% between 2006 and

37 Table 19. Summary of elk harvest in E-31 and E-32, Antlerless Year Bull Harvest Harvest Total Harvest # Hunters % Success % % % % % % % % % % % Average % Elk Harvest in E-31 and E-32 Bull Harvest Anterless Harvest Total Hvst Linear (Bull Harvest) Linear (Anterless Harvest) Linear (Total Hvst) Figure 26. Trends in elk harvest in E-31 and E-32, CO, from

38 Figure 27 shows the trend in elk hunter numbers and hunter success rates in CO s E-31 and E-32. Elk hunter numbers peaked in 2006 at 20,896, then began a declining trend. In the last 6 years hunter numbers ranged from 15,000-17,000hunters/year. Hunter success rates showed a steady decline from 23.5% in 2006 to only 14.4% in 2016, the second lowest rate in the past 11 years. Elk Hunter Numbers and Hunter Success: E-31 and E-32 # Hunters % Success Linear (% Success) % % 15.0% 10.0% 5.0% Figure 27. Hunter numbers and hunter success rates in E-31 and E % Southern Ute Indian Reservation Table 20 shows the annual elk harvest on the SUIR from Average annual elk harvest on the SUIR was 37 bulls and 119 cows. Total elk harvest ranged from elk/year. Figure 28 sows the trend in annual elk harvest on the SUIR from Bull and cow harvest have been relatively stable, with only minor increases in harvest in some years. The SUIR elk harvest accounts for approximately 5% of the annual elk harvest in the CO portion of the CPLA area. Hunter success rates on the SUIR ranged from approximately 15-25% for bull elk and 25-30% for cow elk. 38

39 Table 20. Summary of elk harvest, SUIR, Year Bull Harvest Cow Harvest Total Elk Harvest Average Annual Elk Harvest on the SUIR Bull Harvest Cow Harvest Total Elk Harvest Linear (Bull Harvest) Linear (Cow Harvest) Linear (Total Elk Harvest) Average Figure 28. Trends in annual elk harvest on the SUIR,

40 New Mexico Table 21 summarizes elk harvest in the north-central herd of NM, plus GMU 2. Figure 29 shows the trend in annual elk harvest in the NM GMU s within the CPLA area. Harvest of both bulls and cows has increased steadily since From bull elk harvest increased by 54%, cow elk harvest by 140%, and total elk harvest by 85%. Hunter success rates averaged 43% and ranging from 38-49%. Table 21. Summary of elk harvest in the NM GMU s 2,4,5A,5B,50,51 and 52. Year Bulls Cows Total Harvest # Hunters % Success Average Jicarilla Apache Reservation Table 22 summarizes elk harvest and hunter success rates on the JAR from Bull elk harvest averaged 135 bulls/year and ranged from bulls/year. Cow elk harvest averaged 465 cows/year and ranged from cows/year. Although the trendlines indicate a slightly decreasing trend in elk harvest since 2006, cow harvest and total elk harvest have increased since 2012 (Figure 30). 40

41 Elk Harvest in NM GMU's Bulls Cows Total Hvst Linear (Bulls) Linear (Cows) Linear (Total Hvst) Figure 29. Trend in annual elk harvest in the NM GMU s 2,4,5A,5B,50,51, and 52, Table 22. Elk harvest and hunter success on the JAR, Year # Bulls # Cows Total Elk # Hunters Hunter Success Average

42 Elk Harvest on the JAR # Bulls # Cows Total Elk Linear (# Bulls) Linear (# Cows) Linear (Total Elk) Figure 30. Trend in elk harvest on the JAR, Combined Jurisdictions Table 23 summarizes bull elk harvest in the CPLA area from Bull harvest is shown for each of the 4 jurisdictions and for CO and NM separately. Total bull elk harvest in the CPLA area ranged from a low of 3239 in 2008 to a high of 4110 in The average annual bull elk harvest from was 1874 bulls/year in CO and 1828 bulls/year in NM. Figure 31 shows the trend in annual bull elk harvest for the CO and NM portions of the CPLA area. Bull harvest in the CO portion has trended downward since 2006, and the 2016 harvest of 1629 bulls was the second lowest recorded. In NM bull elk harvest has trended sharply upward and the 2016 harvest of 2067 bulls was the highest recorded since Considering the extent that CO and NM share this migratory elk herd it was surprising to find the exact opposite trend in annual bull elk harvest. It is work noting that in CO, all of the elk harvested are summer residents; while in NM the harvest is comprised of a mix of resident elk and winter migrants from CO. 42