Mojave Desert Tortoise Long Term Population Trends within the Red Cliffs NCA
Project ID: 6783
Status: Completed
Fiscal Year: 2023
Submitted By: 233
Project Manager: Ann Mcluckie
PM Agency: Utah Division of Wildlife Resources
PM Office: Southern Region
Lead: Utah Division of Wildlife Resources
WRI Region: Southern
Description:
This is a jointly funded project between BLM and ESMF to assess current Mojave desert tortoise (Gopherus agassizii) population status, and long-term population trends within the RC NCA and RCDR.
Location:
This project will occur within the Red Desert National Conservation Area and Red Cliffs Desert Reserve, Washington County, Utah.
Project Need
Need For Project:
Long term population monitoring is a critical component of the USFWS Mojave Desert Tortoise Recovery Plan and is an integral part of the delisting criteria. For example, rate of population change should be increasing for at least one tortoise generation (e.g., 25 years) in all recovery units to warrant delisting (USFWS 1994, 2011). The primary goal of Year 1 (Phase 1) of this project is to determine the current tortoise density, and long-term demographic and population trends for desert tortoises within the Red Cliffs NCA, the primary conservation area in the UVRRU. Obtaining population estimates in calendar year 2023, exactly 25 years since full scale implementation of the monitoring program, will allow for trend evaluation of one tortoise generation, an important recovery criterion. Under the 1995 HCP, the County provided substantial funding to support baseline monitoring that demonstrated the efficacy of the conservation program and provided an understanding of population trends within the UVRRU (Allison and McLuckie 2018; McLuckie et al. 2020). Since the implementation of the Restated and Amended HCP the County has not provided funding to support regional monitoring activities, hence, regional monitoring has not been conducted since 2019. A secondary goal of the project is to evaluate the effectiveness of the recovery program and implement appropriate adaptive management strategies to recover desert tortoises in the UVRRU.
Objectives:
The primary goal of Phase 1 of this project, Mojave Desert Tortoise Long Term Population Trends within the Red Cliffs NCA and Desert Tortoise Population Status Assessment within the Beaver Dam Wash NCA, is to determine current population status, and long-term population demographic and population trends within the Red Cliffs NCA, the primary conservation area in the UVRRU. Obtaining population estimates in calendar year 2023, exactly 25 years since full scale implementation of the monitoring program, will allow for trend evaluation of one tortoise generation, which is identified as an important recovery criterion, and will provide for an understanding of long-term impacts from recent large-scale fires (e.g., Turkey Farm Road and Cottonwood Trail Fire) in the Red Cliffs NCA during the summer of 2020. Specific project objectives of regional long term monitoring within the Red Cliffs NCA include the following: (1) complete effectiveness monitoring by sampling long term desert tortoise monitoring plots in Management Zones 2, 3, 4, and 5; (2) hire, supervise, train, and coordinate field crew; (3) track radiotelemetered tortoises to quantify above ground activity during surveys; (4) evaluate and assess size class distribution, sex ratios, growth rates on marked animals, and health; (5) collect presence data on BLM Sensitive species observed on transects and in the field; (6) analyze monitoring data (1998 to 2023) and assess adult population density, abundance and long term trends; (7) evaluate population status and assess effectiveness of management actions (e.g., fencing, habitat rehabilitation, translocation, etc.); (8) provide an assessment of plant community status across the landscape (e.g., species present, % cover); and (8) analyze data and prepare annual and final reports for BLM and agency partners. In addition, UDWR will pursue additional funding (e.g., ESMF, Washington County HCP) to support surveys on adjacent nonfederal lands (e.g., UDNR, SITLA) and assess tortoise population status across the entire conservation area (e.g., Management Zones 2, 3, and 5 within the Red Cliffs Desert Reserve).
Project Location/Timing Justification (Why Here? Why Now?):
The desert tortoise, and its associated habitat, the Mojave Desert, are at risk of crossing ecological thresholds due to anthropologic pressures and disturbances that erode natural resilience and increase their susceptibility to large stochastic disturbances (e.g., wildfires). Monitoring of desert tortoise demographics and population trends, while simultaneously implementing adaptive management actions (e.g., habitat restoration, translocation, fence maintenance, education) can help avoid reaching these thresholds. In addition, population response monitoring to management actions can help managers better identify ecological thresholds for the desert tortoise and its habitat, enhancing the adaptive management process.
Relation To Management Plan:
The goals and objectives of this project are consistent with 46 goals and objectives from 16 management plans. This project closely follows those recommendations listed in the Revised Recovery Plan for the Mojave Population of the Desert Tortoise (USFWS 2011) and the Recovery Plan for the Desert Tortoise (Mojave Population; USFWS 1994). Additionally, the Red Cliff's NCA RMP and the St. George Field Office RMP call for proactive vegetation management efforts to protect a variety of resources, including wildlife, recreation, and cultural. Revised Recovery Plan for the Mojave Population of the Desert Tortoise (USFWS 2011) and the Recovery Plan for the Desert Tortoise (Mojave Population; USFWS 1994) * Develop, support, and build partnerships to facilitate recovery (1) * Protect existing populations and habitat (2); Conserve intact desert tortoise habitat (2.1); Restore desert tortoise habitat (2.6) * Augment depleted populations through a strategic program (3); Implement translocations in target areas to augment populations (3.4) * Monitor progress towards recovery (4); Monitor desert tortoise population growth (4.1); Monitor the extent of tortoise distribution in each recovery unit (4.2); Quantify the presence and intensity of threats to the desert tortoise across the landscape (4.4) * Conduct research on the restoration of desert tortoise habitat (5.2) * Implement an adaptive management program (6) Recovery Action Plan for the Mojave Desert Tortoise in the Upper Virgin River (USFWS 2014) * Restore habitat in burned or otherwise disturbed areas; identify polygons of high potential or importance and create islands of seeded or planted habitat to enhance recovery (Priority 1, 4.02). * Conduct habitat restoration by controlling cheat grass and other non-native and invasive plant species (Priority 1, 4.05). * Restore habitat with large-scale seeding or plantings within the Reserve (Priority 2, 4.03). Recovery Action Plan for the Mojave Desert Tortoise in the Northeast Mojave (USFWS 2014) * Reduce coverage of exotic annual grasses and thus fire risk, and increase the coverage of native species and plant diversity (Priority 1, 1.02). * In recently-burned habitat on the Beaver Dam Slope, re-seed multiple polygons, no smaller than 40 acres each (Priority 3, 1.12). Washington County Habitat Conservation Plan (WC 1995) and Amended and Restated Washington County Habitat Conservation Plan (WC 2021) * Preserve and enhance desert tortoise populations and their habitat within the Red Cliffs Desert Reserve (WC 1995, 1.5). * Provide protection for other listed and candidate species and their habitats (WC 1995, 1.5). * Fund surveys and other actions to help gather information and identify and implement actions to help other listed and candidate species (WC 1995, 1.5). * Translocate displaced desert tortoises to the Reserve or other designated translocation site thereby expanding the protected desert tortoise population (WC 2020, 6.1.2). * Monitoring tortoise population trends and threats to support adaptive management actions (WC 2020, 6.1.2). Utah Wildlife Action Plan (UDWR 2015) * Assess distribution and abundance of species with greatest conservation need (pg. 7). * Implement research or surveys to identify and understand the key factors in effective restoration and conservation (pg. 7). * Build partnerships among agencies and stakeholders to abate threats for priority species (pgs. 217-224). * Implement monitoring to measure the effectiveness of conservation actions and to adapt conservation to changing conditions (pgs. 213-215). Gila Monster Conservation Strategy (UDWR 2007) * Identify, maintain, protect, and enhance important habitat to protect and conserve Gila monsters in southwestern Utah (Goal 2). * Identify and implement management actions that would protect and enhance Gila monster habitat (2.2). * Maintain biological integrity of protected habitat areas (i.e., Red Cliffs Desert Reserve, 3.1.1). Utah Comprehensive Wildlife Conservation Strategy (UDWR 2005) * General Conservation Action to control and monitor invasive species with specific conservation action to protect and maintain habitat (6-2, 6-7). * Restore degraded habitat by managing previously or potentially suitable habitat to achieve or approach properly functioning condition with specific conservation action to maintain habitat integrity (6-2, 6-7). * General Conservation Action to control and monitor invasive species with specific conservation action to protect and maintain habitat (6-2, 6-7). Dixie Resource Area Resource Management Plan (BLM 1998) and Resource Management Plan for the Red Cliffs and Beaver Dam Wash National Conservation Areas (BLM 2016) * Maintain wildlife habitats in properly functioning conditions to support natural wildlife diversity, reproductive capability, and appropriate human use and enjoyment (2.24). * Manage suitable public land habitats for the recovery or reestablishment of native populations through collaborative planning with local, state, and federal agencies, user groups, and interested organizations (2.24). * Work with state, local, and other federal partners to minimize or eliminate the need for additional listing of species under the Endangered Species Act in Washington County (2.24). Utah Mule Deer Statewide Management Plan (UDWR 2014) * Expand and improve mule deer populations throughout the state within the carrying capacity of available habitats and in consideration of other land uses (VI, pg 17). * Conserve, improve, and restore mule deer habitat throughout the state with emphasis on crucial ranges (VI, pg. 18). Landscape Conservation Forecasting for Washington County's National Conservation Areas (TNC 2011) * Improve or maintain condition of all ecological systems; improve the condition of ecological systems that are currently in an undesirable (highly departed) condition (Pg. 4-5). * For the six ecological systems that are vital tortoise habitat, reduce departure from desired future condition (tortoise habitat departure) from high to low (Pg 4). * Protect reference vegetation classes, unburned and only once-burned shrubland classes (Pg. 4). * Decrease fuel loading and continuity to help reduce risk of loss from wildlife to natural and cultural resources in the NCA's (Pg. 4). Southwest Utah Support Area Fire Management Plan, Cedar City Office (BLM 2004) * Prevent invasive species and restore watershed function and biological communities through short term stabilization and long term rehabilitation (II,A., pg. 11). * Restore healthy, diverse, and resilient ecological systems to minimize uncharacteristically severe fires on a priority watershed basis through long-term restoration (II,A., pg. 11). Virgin River (Watershed) Management Plan (WCWCD, 2006) * To maintain and enhance water quality and associated natural resources of the Virgin River Watershed by reducing soil erosion, wildfires and flooding (Chapter 1, III-14). Desert Tortoise Management Plan, Snow Canyon State Park, Washington County, Utah (UDWR 2004) *Protect existing desert tortoise habitat within SCSP to prevent habitat loss and fragmentation (Objective 1.2) *Rehabilitate and enhance disturbed habitat to maintain ecosystem integrity and health of tortoise populations (Objective 1.3) *Maintain comprehensive, up-to-date information on tortoise and other sensitive wildlife populations, and their habitats (Objective 4.1)
Fire / Fuels:
Not applicable.
Water Quality/Quantity:
Not applicable.
Compliance:
Compliance under Federal and State law is required and has been completed through the Habitat Conservation Plan process.
Methods:
Phase 1. The sampling methodology will be consistent with the desert tortoise long-term monitoring programs implemented range wide across the Mojave desert (Allison and McLuckie 2018) and described by Anderson and Burnham (1996). The monitoring program will consist of two independent teams of observers, one surveying permanent transects and the other estimating above ground activity using telemetered tortoises. Population monitoring efforts will be concentrated on federal lands within Management Zones 2, 3 and 5 in the Red Cliffs NCA. We will pursue additional funding from ESMF and Washington County to survey transects on adjacent SITLA and UDNR lands within the Red Cliffs Desert Reserve (Table 1). Long term permanent random transects, established in 1998, will be resurveyed within the NCA to assess population trends from April to mid-June (Figure 1). Each transect is 2 km in length, and either shaped in a square, with 500 m sides, or linear. Due to the small and irregular size of Zone 5 linear transects were placed laterally, perpendicular to high concentrations of tortoises. Transects are within tortoise habitat, defined as areas below 1,200 m (4000 ft). Transect start points and corners were permanently marked, beginning in 1998, with 16" rebar, and painted red with enamel exterior spray paint to facilitate relocation. Each transect start point or corner is permanently labeled using double-faced aluminum tags identifying the transect number and directional orientation of each corner (i.e., NE, SE, NW, SW). Transects will be surveyed by a two person crew using a three-pass survey technique to search on and near the transect centerline. Using a compass to check directional alignment, a 50 m surveyor tape will be pulled along the transect line by the first observer. Then, both observers will walk in a sinusoidal pattern on opposite sides of the transect line, crossing over the surveyor tape, to ensure that all tortoises are detected. Finally, the first observer will walk directly back along the transect line to ensure that all tortoises on the line are detected. Search efforts will extend to 12 m from the transect line, with particular focus near the center, 3 to 5 m from the line. This procedure will be repeated in 50 m increments, with the roles of the surveyors reversing each time, until the entire 2 km transect is completed. The tortoises location relative to the three pass search pattern will be noted to quantify any tortoises missed on the transect line and evaluate crew performance. Snake sticks and signal mirrors will be used to search under bushes and within deep shelters, particularly along the transect line. The surveyed length of each transect will be calculated as the straight-line distance between GPS coordinates at start and end points, excluding areas that could not be surveyed. When tortoises are detected, we will measure the perpendicular distance from the line using a 30 m open reel fiberglass tape. In addition, distance along the transect line, UTM coordinates, dominant vegetation, environmental variables (ambient/surface temperatures, percent humidity, cloud cover, wind speed), and time detected will also be recorded. Standard tortoise carapace measurements will be taken using a caliper and ruler including carapace length (CL), width at the third and fourth marginal seam (post M3), and width at the seventh and eighth marginal seam (M7/M8). Additional data collected included sex (determined for adult tortoises only), time found, behavior, health observations (Berry and Christopher 2001), parasites observed (e.g., ticks, mites), injuries, shell wear (Berry and Woodman 1984) and shell anomalies. If a tortoise cannot be removed from a burrow, it will be visually estimated as either reproductive or nonreproductive. For future identification, each tortoise (CL > 100 mm) will be given a unique mark by notching marginal scutes with a triangular file. The carapace of each tortoise will be photographed for future reference. We will use latex gloves while handling each tortoise and disinfected equipment with a diluted bleach solution (1:10 dilution of 5.25% bleach) after use (Brown et al. 2003). Once processing is complete, tortoises will be released at the point of detection. For each shell remain found, CL, sex, UTM coordinates, signs of predator or scavenger, percent scutes and bones present, position of shell, estimated time since death, and perpendicular distance from the transect line will be recorded. The CL of deteriorated or fragmented shell remains will be estimated using regressions based on scute size (Berry and Woodman 1984). Time since death will be estimated using deterioration rates of tortoise shell and skeletal remains (Berry and Woodman 1984). All processed shell remains will be photographed. The proportion of tortoises visible (go) during the monitoring period will be estimated by simultaneously tracking a subset of radioed tortoises. Tortoises seen on the surface or in burrows with only the aid of mirrors will be identified as "visible" while tortoises deep in burrows or hidden in dense vegetation will be considered undetectable and therefore "not visible" (Anderson and Burnham 1996). Radioed tortoises will be located using a Telonics receiver (Model TR-2E) and directional antenna. Telemetered tortoises will be monitored two to three times a week at a representative site located in the central portion of Management Zone 3 of the Reserve and NCA. During the first week, field crews will be intensively trained on distance sampling theory, field protocols and search patterns. Polystyrene desert tortoise models of two sizes (adults and juveniles) will be placed on a training course in Management Zone 3 to train crews on the search technique, improve the detection function, maintain detection shoulders, measure the perpendicular distance of each model to the transect line accurately, and use of orientation equipment (e.g., compass, GPS). Data will be checked daily for quality and analyzed weekly to assess the detection histogram and improve search efforts. Field crews will be regularly rotated between distance sampling and radio telemetry to allow training in the overall survey method and to improve technicians' tortoise search image. To assess overall habitat condition, vegetation cover will be assessed at a minimum of one transect corner (e.g., NE, NW, SE, SW) for each transect. Within a flagged 10 m radius circle at the designated transect corner, each perennial and annual species will be assigned a cover class category based on its % cover within the flagged area as follows: 1 = trace, 2=0-1%, 3=1-2%, 4=2-5%, 5=5-10%, 6=10-25%, 7=25-50%, 8=50-75%, 9=75-95%, and 10=>95%. Overall vegetation composition and percent ground cover will be assessed, including unburned and fire disturbed habitat, within the NCA study area. We will use Program DISTANCE 7.3 Release 1 (Thomas et al. 2010) to estimate density and abundance within Management Zone 3 as well as across the Reserve (Zones 2, 3 & 5). To account for tortoises not visible or detected during sampling, including those deep in burrows or hidden in dense vegetation, we will use the correction factor, , and incorporate that value into population estimates. We will assess population trends by comparing current estimates with UDWR's long term monitoring data collected from 1998 to 2019. Survey and observation records will be compiled and provided in geodatabase format (Microsoft Excel) and ArcGIS spatial layers identifying sampled areas, transects surveyed, shell remain locations, tortoise locations, and other conservation species observed. In the final report, we will include the following: overall field effort, habitat condition, tortoise size class distribution, tortoises marked and recaptured, sex ratios, health observations and assessments, mortality, growth rates, density and abundance estimates, and overall population trend.
Monitoring:
Project monitoring and evaluation will include tracking the following: (1) number of transects surveyed weekly; (2) total km surveyed during the field season; and (3) total number of field days. We will complete weekly progress reports (Year 1: April to mid-June) to track weekly progress during the field season and complete end of year progress reports to track overall project performance. We will complete draft and final reports for each phase of the project: (1) Mojave Desert Tortoise Long Term Population Trends within the Red Cliffs NCA.
Partners:
Much of the success and HCP accomplishments are due to continued partnerships with local and federal agencies. The project will be implemented by the Utah Division of Wildlife Resources in cooperation with Washington County Habitat Conservation Plan, Bureau of Land Management, U.S. Fish and Wildlife Service, Utah Division of Parks and Recreation, and local government agencies (Washington County, City of Ivins, Santa Clara, Hurricane, St. George, Springdale). Working closely with Bureau of Land Management, we secured BLM funding to implement long term monitoring on federal lands within the Red Cliffs Desert Reserve during spring 2023.
Future Management:
The information obtained through this project will be used to develop ongoing management strategies to assist in the implementation of the Amended and Revised HCP and ultimately recover the desert tortoise. This information will help the HCP staff, HCAC, Technical Committee, and agency personnel better assess potential threats to the desert tortoise population, and understand tortoise survival and mortality within the Reserve. Implementation of the proposed project will result in long-term benefits to tortoise populations by reducing and minimizing threats. This project is an integral component of the collaborative HCP process, which is a largescale Endangered species 25 year mitigation effort to allow continued economic development and growth in Washington County while establishing the Red Cliffs Desert Reserve to ensure the long-term persistence of the desert tortoise.
Sustainable Uses of Natural Resources:
The Red Cliffs Desert Reserve includes 96 recreational trails which are popular with rock climbers, hikers, mountain bikers, equestrian users, birdwatchers, wildlife watchers, and hunters. In 2021, over 800,000 people visited the Reserve, with visitation expected to increase annually. Protecting and restoring habitat will not only benefit wildlife but the recreational experience for thousands of visitors.
Budget WRI/DWR Other Budget Total In-Kind Grand Total
$65,540.70 $71,479.10 $137,019.80 $0.00 $137,019.80
Item Description WRI Other In-Kind Year
Personal Services (seasonal employee) Seasonal technician personnel costs to assist with completing tortoise surveys and tracking telemetered tortoises. $0.00 $71,479.10 $0.00 2023
Personal Services (permanent employee) Personnel costs for permanent biologist to supervise and train monitoring crew. Funding will come from existing ESMF project. $65,540.70 $0.00 $0.00 2023
Funding WRI/DWR Other Funding Total In-Kind Grand Total
$65,540.70 $71,479.10 $137,019.80 $0.00 $137,019.80
Source Phase Description Amount Other In-Kind Year
BLM (T&E) A174 Funding provided through BLM Cooperative Agreement, L22AS00196, St. George Field Office Threatened and Endangered Species (TES) Program. $0.00 $71,479.10 $0.00 2023
Species Protection Account E201 This ESMF request is part of an existing ESMF proposal that was awarded funding. We are not requesting additional funds but rather allocating funds that have already been awarded. $65,540.70 $0.00 $0.00 2023
Species
Species "N" Rank HIG/F Rank
Mojave Desert Tortoise N3
Threat Impact
Disease – Alien Organisms High
Mojave Desert Tortoise N3
Threat Impact
Droughts Very High
Mojave Desert Tortoise N3
Threat Impact
Inappropriate Fire Frequency and Intensity Very High
Mojave Desert Tortoise N3
Threat Impact
Invasive Plant Species – Non-native Very High
Habitats
Habitat
Mojave Desert Shrub
Threat Impact
Inappropriate Fire Frequency and Intensity Very High
Mojave Desert Shrub
Threat Impact
Invasive Plant Species – Non-native Very High
Project Comments
Comment 08/24/2023 Type: 2 Commenter: Daniel Eddington
This is just a reminder that completion reports are due August 31st. I have entered the expenses in the Through WRI/DWR column on the finance page. Please do not make any changes to numbers in the Through WRI/DWR column. Any "Through Other" or "In-kind" expenses will need to be entered by the PM or contributors. Be sure to click on the finalize button on the completion report when you have your completion report ready to be reviewed by WRI Admin. Don't forget to upload any pictures of the project you have of before, during and after completion. If you have any questions about this don't hesitate to contact me. Thanks
Completion
Start Date:
07/01/2022
End Date:
06/30/2023
FY Implemented:
2023
Final Methods:
The sampling methodology was consistent with the desert tortoise long-term monitoring programs implemented range wide across the Mojave desert (Allison and McLuckie 2018) and described by Anderson and Burnham (1996). The monitoring program consisted of two independent teams of observers, one surveying permanent transects and the other estimating above ground activity using telemetered tortoises. Population monitoring efforts were concentrated on federal lands within Management Zones 2, 3, 4 and 5 in the Red Cliffs NCA. Long term permanent random transects, established in 1998, were resurveyed within the NCA to assess population trends from April to mid-June. Each transect is 2 km in length, and either shaped in a square, with 500 m sides, or linear. Due to the small and irregular size of Zone 5 linear transects were placed laterally, perpendicular to high concentrations of tortoises. Transects are within tortoise habitat, defined as areas below 1,200 m (4000 ft). Transect start points and corners were permanently marked, beginning in 1998, with 16" rebar, and painted red with enamel exterior spray paint to facilitate relocation. Each transect start point or corner was permanently labeled using double-faced aluminum tags identifying the transect number and directional orientation of each corner (i.e., NE, SE, NW, SW). Transects were surveyed by a two person crew using a three-pass survey technique to search on and near the transect centerline. Using a compass to check directional alignment, a 50 m surveyor tape was pulled along the transect line by the first observer. Then, both observers walked in a sinusoidal pattern on opposite sides of the transect line, crossing over the surveyor tape, to ensure that all tortoises were detected. Finally, the first observer walked directly back along the transect line to ensure that all tortoises on the line were detected. Search efforts extended to 12 m from the transect line, with particular focus near the center, 3 to 5 m from the line. This procedure was repeated in 50 m increments, with the roles of the surveyors reversing each time, until the entire 2 km transect was completed. The tortoises location relative to the three pass search pattern was noted to quantify any tortoises missed on the transect line and evaluate crew performance. Snake sticks and signal mirrors were used to search under bushes and within deep shelters, particularly along the transect line. The surveyed length of each transect was calculated as the straight-line distance between GPS coordinates at start and end points, excluding areas that could not be surveyed. When tortoises were detected, we measured the perpendicular distance from the line using a 30 m open reel fiberglass tape. In addition, distance along the transect line, UTM coordinates, dominant vegetation, environmental variables (ambient/surface temperatures, percent humidity, cloud cover, wind speed), and time detected were also recorded. Standard tortoise carapace measurements were taken using a caliper and ruler including carapace length (CL), width at the third and fourth marginal seam (post M3), and width at the seventh and eighth marginal seam (M7/M8). Additional data collected included sex (determined for adult tortoises only), time found, behavior, health observations (Berry and Christopher 2001), parasites observed (e.g., ticks, mites), injuries, shell wear (Berry and Woodman 1984) and shell anomalies. If a tortoise could not be removed from a burrow, it was visually estimated as either reproductive or nonreproductive. For future identification, each tortoise (CL > 100 mm) was given a unique mark by notching marginal scutes with a triangular file. The carapace of each tortoise was photographed for future reference. We used latex gloves while handling each tortoise and disinfected equipment with a diluted bleach solution (1:10 dilution of 5.25% bleach) after use (Brown et al. 2003). Once processing was completed, tortoises were released at the point of detection. For each shell remain found, CL, sex, UTM coordinates, signs of predator or scavenger, percent scutes and bones present, position of shell, estimated time since death, and perpendicular distance from the transect line were recorded. The CL of deteriorated or fragmented shell remains were estimated using regressions based on scute size (Berry and Woodman 1984). Time since death was estimated using deterioration rates of tortoise shell and skeletal remains (Berry and Woodman 1984). All processed shell remains were photographed. The proportion of tortoises visible (go) during the monitoring period was estimated by simultaneously tracking a subset of radioed tortoises. Tortoises seen on the surface or in burrows with only the aid of mirrors were identified as "visible" while tortoises deep in burrows or hidden in dense vegetation were considered undetectable and therefore "not visible" (Anderson and Burnham 1996). Radioed tortoises were located using a Telonics receiver (Model TR-2E) and directional antenna. Telemetered tortoises were monitored two to three times a week at a representative site located in the central portion of Management Zone 3 of the Reserve and NCA. During the first week, field crews were intensively trained on distance sampling theory, field protocols and search patterns. Polystyrene desert tortoise models of two sizes (adults and juveniles) were placed on a training course in Management Zone 3 to train crews on the search technique, improve the detection function, maintain detection shoulders, measure the perpendicular distance of each model to the transect line accurately, and use of orientation equipment (e.g., compass, GPS). Data was checked daily for quality and analyzed weekly to assess the detection histogram and improve search efforts. Field crews were regularly rotated between distance sampling and radio telemetry to allow training in the overall survey method and to improve technicians' tortoise search image. To assess overall habitat condition, vegetation cover was assessed at one transect corner (e.g., NE, NW, SE, SW) for a representative number of transects. Within a flagged 10 m radius circle at the designated transect corner, each perennial and annual species was assigned a cover class category based on its % cover within the flagged area as follows: 1 = trace, 2=0-1%, 3=1-2%, 4=2-5%, 5=5-10%, 6=10-25%, 7=25-50%, 8=50-75%, 9=75-95%, and 10=>95%. Overall vegetation composition and percent ground cover was assessed, including unburned and fire disturbed habitat, within the NCA study area. We will use Program DISTANCE 7.3 Release 1 (Thomas et al. 2010) to estimate density and abundance within Management Zone 3 as well as across the Reserve (Zones 2, 3 & 5). To account for tortoises not visible or detected during sampling, including those deep in burrows or hidden in dense vegetation, we will use the correction factor and incorporate that value into population estimates. We will assess population trends by comparing current estimates with UDWR's long term monitoring data collected from 1998 to 2019. Survey and observation records will be compiled and provided in geodatabase format (Microsoft Excel) and ArcGIS spatial layers identifying sampled areas, transects surveyed, shell remain locations, tortoise locations, and other conservation species observed. In the final report, due in March 2024, we will include the following: overall field effort, habitat condition, tortoise size class distribution, tortoises marked and recaptured, sex ratios, health observations and assessments, mortality, growth rates, density and abundance estimates, and overall population trend.
Project Narrative:
Eight field technicians, hired for desert tortoise population monitoring, completed distance sampling training from April 3 to April 7, focusing on search methodology at mock transects in Hurricane and radio tracking tortoises at the telemetry site to assess surface activity and hone tortoise search skills. From April 10 to June 13, 2023, we surveyed 314.64 km (161 transects) in the Red Cliffs National Conservation Area (RCNCA) and Snow Canyon State Park (SCSP), within Management Zones 2, 3, 4 and 5 of the Red Cliffs Desert Reserve (RCDR). Transect lengths ranged from 1.42 to 2.00 km. Depending on the number of survey teams and the topography surveyed, 4.00 to 10.00 kilometers (x= 6.99 km/day) were completed per day. Approximately 2,687 field hours were spent monitoring desert tortoises over 45 workdays. We encountered 149 adult tortoises (i.e., 69 males, 70 females, 10 unknown) during population monitoring either on or adjacent to transects or at the telemetry site. Of those, sex was undetermined for ten tortoises because they were in deep burrows and could not be removed. In addition, we observed 26 juvenile tortoises, defined as individuals with less than 180 mm carapace length. Of the total tortoises observed (n=175), 15% were juvenile tortoises. Fifty-one processed tortoises (31%) were previously marked including one recapture within the same monitoring year (i.e., 2023). Tortoises were observed up to 40.62 m from the transect line, with the majority of tortoises observed within 8 m of the line (54%). A cursory analysis of the cumulative perpendicular distances show that the data follows the recommended shape criterion with detection highest near the line, a shoulder of detection and a gradual decrease in observations with distance to the transect line. Clinical signs similar to those reported for Upper Respiratory Tract Disease (URTD) were observed in 7% (n=11) of the processed adult tortoises (5 males, 6 females). Tortoises with URTD clinical signs were found in City Creek (2), Cottonwood Wash, Industrial Wash, Mill Creek, Padre Canyon, Pioneer Park (2), Red Cliffs (2) and Red Hills Parkway. Health could not be assessed for tortoises that were deep in soil burrows or tucked deeply in their shells (n=14). Tortoises that were identified with URTD clinical signs had one or more of the following: swollen or sunken eyes with discharge, nares that were either moist (i.e., damp or wet) with exudate present (i.e., clear, cloudy or thick, with bubbles) and mild to severe discharge severity, or one or both nares completely impacted, in addition to labored breathing (i.e., wheezing). Two processed tortoises were observed with Bromus tectorum and B. rubens seeds in either the mouth, nare or eye causing swelling, discharge or an abscess in the cheek region. We observed seven tortoises with shell disease covering a portion of their carapace scutes in Babylon, Industrial Wash, Padre Canyon, Paradise Canyon (2), Snow Canyon State Park and the telemetry site. Five burned tortoises were observed with scarring on the forelimbs, peeling scute laminae, sloughed scutes and bone exposed in Middleton, Mill Creek (2), Twist Hollow and the telemetry site. A total of 12 shell remains were observed during distance sampling monitoring in several stages of decay. The majority of shell remains were observed within Zone 3; one shell remain was found in Zone 4 and one in Zone 5. Sex was determined for five adult tortoise shell remains (2 M: 3 F). We estimated four of the remains to have died within the year and cause of death was unknown for the majority of remains observed. One adult male shell was wedged in a deep sandstone fissure at Twist Hollow; likely the tortoise fell in the crack, was unable to get out, and ultimately died. We observed one juvenile shell in a deep sandstone burrow adjacent to Red Hills Parkway with advanced shell fungus on the carapace. We observed a heavily scavenged adult male shell at the entrance of an active coyote den in the City Creek area; time since death was estimated at greater than four years. Finally, one fresh juvenile shell remain was observed at City Creek; cause of death was attributed to predation (e.g., coyote) due to the fully severed shell with canine puncture mark on the right rear costal. Shells were located in Babylon, City Creek (2), East Valley, Hurricane Cinder Knolls, Middleton (2), Pioneer Park, Red Cliffs Recreation Area, Red Hills Parkway, Twist Hollow and the telemetry site. Thirteen radiotelemetered tortoises were used to estimate above ground activity (go) during the sampling period. Average carapace length of radiotelemetered tortoises was 259 mm ± 8.55 (n=13; range = 217-327). The proportion of time a telemetered tortoise spent above ground during the monitoring period varied from 45 to 85 percent. The weekly mean go during 2023 tortoise monitoring was 0.71 ± 0.05 (n=10; range 0.46 to 0.96). We observed extensive plant growth and high diversity throughout the spring, a result of above average winter precipitation. Temperatures were cool during the initial monitoring week with above ground tortoise activity relatively low (38%). Weekly tortoise surface activity continued to increase as temperatures warmed. During the first week of May, thunderstorms brought significant precipitation across the NCA and limited, local monsoon activity was present from mid to late May. Relative to previous monitoring years, spring ambient temperatures (e.g., May, April, June) were below average with ambient temperatures below 36.9 degrees C (98.4 degrees F) the entire season. Tortoise surface activity peaked the first week of May, steadily decreasing by the end of the season. Abundant winter precipitation produced abundant growth of annual and perennial plants that was subsequently choked by aggressive growth of exotic mustards (e.g., Sahara mustard, yellow mustard, London rocket), cheatgrass, red brome, Mediterranean grass, and Russian thistle. Detailed methods and results will be found in the forthcoming UDWR draft report, Regional Desert Tortoise Monitoring in the Red Cliffs Desert Reserve, 2023.
Future Management:
Biologists and managers have identified the desert tortoise as an indicator or umbrella species to measure the health of the desert ecosystem that it inhabits. The tortoise is well suited to its indicator role as it is long lived, takes 15-20 years to reach reproductive maturity, and is sensitive to changes in the environment. By protecting the desert tortoise, other species that are a part of the ecosystem will also benefit under the same conservation "umbrella." Implementation of adaptive management actions to protect and conserve the suite of species within the NCAs, will not only benefit native species and their habitat but the recreational experience for thousands of visitors. The information obtained through this project will be used to develop ongoing management strategies to assist in the adaptive management of the desert tortoise and ultimately recover the species. This information will help biologists and managers better assess potential threats to the desert tortoise population, and understand tortoise survival and mortality within the NCAs. Implementation of the proposed project will result in long-term benefits to tortoise populations by identifying, reducing and minimizing potential threats. In addition, this project is an integral component of the collaborative HCP process, which is a largescale Endangered species 25 year mitigation effort to allow continued economic development and growth in Washington County while establishing the Red Cliffs NCA to ensure the long-term persistence of the desert tortoise.
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