Completion Form

2023

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.

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 ÃÂ± 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 ÃÂ± 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.

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.

Ann Mcluckie

08/30/2023 18:40:50