Christin Moeller’s research while affiliated with Texas A&M University – Kingsville and other places

The Texas Tortoise (Gopherus berlandieri) is a Texas-state threatened species that has experienced sharp declines in population number and its distribution has become patchy. Because of their decline, conservation agencies desire to know remaining population size, but low abundance and limited knowledge of detectability make this difficult. As such, we built a 2.4-ha enclosure, translocated 56 Texas Tortoises into the enclosure, conducted weekly line transects during morning, afternoon, and evening from June–September 2023, recorded temperature and all tortoises observed, and calculated the percent of tortoises observed and their detectability from the known number of tortoises within the enclosure. We observed 4.9 ± 0.5 tortoises (x̄ ± SE) per survey, on average, which constituted an estimated 8.8% detectability of the possible 56 tortoises within the enclosure. The frequency of tortoises observed was not related to temperature (F1, 64 = 0.18, p = 0.67), time of day (F2, 63 = 2.12, p = 0.13), or their interaction (F2, 60 = 2.57, p = 0.08). Therefore, Texas Tortoises in southern Texas can be surveyed at any time during daylight hours during June–September when temperatures range between 24–40°C.

Texas Tortoise (Gopherus berlandieri) populations were once distributed throughout southern Texas with densities estimated as high as 35 tortoises/ha. Recent studies have estimated densities at only 0.26 tortoise/ha, and their distribution has become sporadic throughout their historic range. Populations of Texas Tortoises are thought to be restricted to thornscrub and coastal prairie habitats. Older studies (~50 years) found Texas Tortoises in clay dune (loma) habitat; however, the importance of loma to these tortoises remains unclear. In order to conduct a habitat availability and use analysis for Texas Tortoises in southern Texas, we recorded 171 tortoises within a 270-ha area. Of the eight habitats identified within the study area, only grassland loma was used by Texas Tortoises in greater proportion than available, with 135 tortoises (79%) located within that habitat (11.3% of all available habitat). Tortoises used evergreen loma and non-loma grassland in proportion to habitat availability, and wetlands, open water, woodlands, coastal flats, and shrubland much less than their availability. Density of Texas Tortoises in grassland loma was 4.4 tortoises/ha, a 2.6-fold increase from the next-favoured habitat. Our results suggest that grassland loma is the preferred habitat of Texas Tortoises, more so than other available habitats including thornscrub. Loma habitats should be protected as critical habitat for this state-threatened reptile.

Background Texas tortoises (Gopherus berlandieri) are a Texas-state threatened species. Translocation is often suggested as a mitigation option; however, disease status and the potential for spread must be considered prior to such efforts. Mycoplasma infection of the upper respiratory tract is a concern within tortoise populations, which requires monitoring so translocation efforts do not inadvertently spread the disease. Objectives We determined and compared the prevalences of Mycoplasma agassizii in Texas tortoises from donor and recipient sites in southern Texas prior to translocation, treated Mycoplasma agassizii-infected tortoises with danofloxacin, and developed alternate Mycoplasma agassizii treatments for Texas tortoises. Methods We collected 171 and 23 Texas tortoises from a 270-ha and a 100-ha donor site and recipient site, respectively. We began a regimen of danofloxacin (6 mg/kg body weight injected subcutaneously every other day for 30 days) for tortoises with clinical signs (N = 20). We noted an additional 10 tortoises began displaying clinical signs of upper respiratory tract disease (URTD) after translocation, so we designed a trial to test tulathromycin (5 mg/kg body weight given intramuscularly once/week for 7 weeks) or oxytetracycline (8 mg/kg body weight given subcutaneously once/day for 14 days) as Mycoplasma treatments for symptomatic tortoises. Results Within the donor and recipient sites, 56 (32.7%) and 8 (34.8%), respectively, had antibody titers suggestive of past exposure. Eighteen tortoises from the donor site (10.5%) and 2 from the recipient site (8.7%) displayed clinical signs (i.e., clear serous nasal discharge, conjunctivitis, and palpebral edema) consistent with Mycoplasmal URTD upon initial collection, even though all polymerase chain reaction (PCR) results were negative for active shedding of Mycoplasma agassizii. We ceased treatment after the first dose of danofloxacin due to adverse reactions, which only began to subside after 72 h from the initial dose. Neither tulathromycin or oxytetracycline caused the clinical signs of URTD to subside after a 50-day treatment period. Conclusion Mycoplasma is a persistent issue facing Texas tortoises. Stressors, such as translocation, can cause Mycoplasma-seropositive tortoises to display clinical symptoms of URTD, which can abate without treatment, once the stressor subsides. Implications Danofloxacin, the recommended treatment for Mycoplasma infection in tortoises, is too potent for Texas tortoises.

Texas tortoises (Gopherus berlandieri) were once considered common and abundant throughout southern Texas with densities as high as 16 tortoises per hectare. Today, density estimates are 0.25 tortoises per hectare, which constitutes about a 98% population decline. Because of their low numbers and elusive behavior, Texas tortoises can be difficult to find. We demonstrate the value of using a detector dog as a time saving methodin locating Texas tortoises. Weglued VHFradio transmitters onto 9 adult tortoises and released them in a 5ha plowed and short-grass pasture that contained mesquite (Prosopsis glandulosa) mottes, habitat conducive for Texas tortoise habitat selection. We calculated the Detectability Index (DI) as the detection rate (# tortoises found/ minute) ×percent tortoises from the known population found within 60 minutes. We compared DIs via telemetry, detector dog, and “cold” (no equipment or knowledge) human searches. We used the time required to find all tortoises whenasearcherhadknowledgeoflocationsas thebaseline. Our baseline DI was 0.79, followed by telemetry (0.13) and detector dogs (0.11), while “cold” searches was 0.02. Telemetry, detector dog, and cold searches were 6-fold, 7-fold, and nearly 40-fold slower, respectively, than having knowledge of tortoise locations. However, the combination of using detector dogs with telemetry resulted in a 50% time savings than single methods. Telemetry was useful in locating a generalized area with a tortoise but a detector dog was 2X faster in visually locating the tortoise once the area was identified. Therefore, we recommend the use of detector dogs as a time-saving method when conducting research on Texas tortoises.

HOLBROOKIA LACERATA (Plateau Spot-tailed Earless Lizard). MATING.

Gopherus berlandieri mortality