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Plateau ( Holbrookia lacerata ) and Tamaulipan ( Holbrookia subcaudalis ) spot-tailed earless lizard (STEL) populations have experienced declines in population size and distribution. Both species are considered species of concern and Tamaulipan STEL are being considered for federal threatened status. Even with this heightened concern, little is known about these species. Therefore, our objectives were to determine the most effective and time-efficient methods to survey for STEL, and to determine if a lizard density threshold was required before STEL presence could be detected. We evaluated ten standard reptile search techniques (i.e., pitfall traps, funnel traps, two thermoregulation lures (i.e., rock mounds and cover boards), remote camera surveys, detection dog surveys, quadrant searches, systematic visual searches, environmental DNA sampling, and road cruising) to identify STEL relative abundance within a 1 ha enclosure. The 1 ha enclosure was divided into 100, 10 x 10 m quadrants and each reptile search technique was replicated five times and randomly assigned to a quadrant without replacement. STEL were randomly placed inside the enclosure at known densities of 5, 10, 20, 30, and 40 lizards per ha and their relative abundance was assessed by each method three times at each STEL density during August – September, 2021. STEL were allowed 6-day acclimation periods before increasing density. Because STEL were translocated to novel habitat, caution in interpretation should be noted. However, STEL were not detected using funnel traps, rock mounds, cover boards, remote cameras, and detector dogs at any density level. Pitfall traps, quadrant searches, and eDNA samples detected few STEL, but only at 40 STEL/ha density. Only systematic visual searches and road cruising yielded STEL detections at multiple densities; however, neither method could reliably predict STEL density. Because our detection rates were low (~7% at any STEL density), road cruising can be more time efficient to survey a larger area. Once locations with STEL have been identified, then systematic visual searches between 1300–1500 hr can be conducted to determine the relative abundance of these elusive species.

Wildlife-vehicle collisions can have a substantial influence on the mortality rates of many wildlife populations. Crossing structures are designed to mitigate the impact of road mortality by allowing safe passage of wildlife above or below roads, and connect to suitable areas on both sides of the road. Ocelots ( Leopardus pardalis ) are a federally endangered felid in the United States, with remnant populations of <80 individuals remaining in the Lower Rio Grande Valley of South Texas. Vehicle collisions are the greatest known source of mortality for ocelots in Texas. Crossing structures designed for ocelot use have been implemented throughout South Texas since the 1990s, however, ocelots rarely use them. We compared landscape characteristics between ocelot crossing structures and ocelot-vehicle collision sites. We quantified the spatial distribution of woody and herbaceous cover types surrounding ocelot crossing structures ( n = 56) and ocelot-vehicle collision sites ( n = 26) at multiple spatial extents and compared landscape metrics between these location types. The landscape surrounding ocelot crossing structures had 17–22% more open herbaceous cover >1,050 m from the road, and 1.2–5.8 ha larger herbaceous patches >450 m from the road compared to ocelot-vehicle collision sites. Additionally, many crossing structures installed during the 1990’s are situated >100 km away from an extant ocelot population. Results from this study can guide conservation planners to place future road crossing structures in areas more likely to be used by ocelots. Our results also emphasize that reliable scientific data must be used for effective mitigation efforts. In the absence of data, post-installation assessments can improve the placement of future structures.

Cover crops provide soil cover benefits but can impose allelopathic risks on cotton. We evaluated the functional trade-offs of rye and wheat residues versus purified 2-benzoxazolinone (BOA) under greenhouse conditions. Four experiments applied graded residue or BOA inputs in Pullman clay loam; cotton germination, height, chlorophyll (SPAD), and biomass were measured, and soil BOA, DIBOA, and DIMBOA were quantified by HPLC at designated sampling dates. Responses were dose dependent: BOA reduced germination linearly (−16.5% at 1000 nmol g−1 versus control) and shortened plants, and biomass and SPAD were directionally lower, most evident at 500 nmol g−1, but not statistically significant. Rye showed hormesis at 6400 kg ha−1 (+7.3% germination) and strong inhibition at 12,800 kg ha−1 (−31% germination; biomass up to −45%). Wheat produced intermediate inhibition (biomass −23.7%) and did not affect germination. In soil, benzoxazinoids exhibited significant rate effects at specific sampling dates followed by rapid decline. After storage, BOA showed no residual effects, whereas prior rye still reduced height, SPAD, and biomass. Framed at the agroecosystem scale, maintaining residue biomass below inhibitory thresholds and adjusting termination-to-planting intervals to avoid the early post-termination period, together with species or cultivar choice, can reconcile soil cover services with reliable cotton establishment.

Interspecific interactions among mesocarnivores can influence community dynamics and resource partitioning. Insights into these interactions can enhance understanding of local ecological processes that have impacts on pathogen transmission, such as the rabies lyssavirus. Host species ecology can provide an important baseline for disease management strategies especially in biologically diverse ecosystems and heterogeneous landscapes. We used a mesocarnivore guild native to the southwestern United States, a regional rabies hotspot, that are prone to rabies outbreaks as our study system. Gray foxes ( Urocyon cinereoargenteus ), striped skunks ( Mephitis mephitis ), bobcats ( Lynx rufus ), and coyotes ( Canis latrans ) share large portions of their geographic ranges and can compete for resources, occupy similar niches, and influence population dynamics of each other. We deployed 80 cameras across two mountain ranges in Arizona, stratified by vegetation type. We used two-stage modeling to gain insight into species occurrence and co-occurrence patterns. There was strong evidence for the effects of elevation, season, and temperature impacting detection probability of all four species, with understory height and canopy cover also influencing gray foxes and skunks. For all four mesocarnivores, a second stage multi-species co-occurrence model better explained patterns of detection than the single-species occurrence model. These four species are influencing the space use of each other and are likely competing for resources seasonally. We did not observe spatial partitioning between these competitors, likely due to an abundance of cover and food resources in the biologically diverse system we studied. From our results we can draw inferences on community dynamics to inform rabies management in a regional hotspot. Understanding environmental factors in disease hotspots can provide useful information to develop more reliable early-warning systems for viral outbreaks. We recommend that disease management focus on delivering oral vaccine baits onto the landscape when natural food resources are less abundant, specifically during the two drier seasons in Arizona (pre-monsoon spring and autumn) to maximize intake by all mesocarnivores.

Identification of buildings from remotely sensed imagery in urban and suburban areas is a challenging task. Light detection and Ranging (LiDAR) provides an opportunity to accurately identify buildings by identification of planar surfaces. Dense vegetation can limit the number of light particles that reach the ground, potentially creating false planar surfaces within a vegetation stand. We present an application of discriminant analysis (a commonly used statistical tool in decision theory) to classify polygons (derived from LiDAR) as either buildings or a non-building planar surfaces. We conducted our analysis in southern Texas where thornscrub vegetation often prevents a LiDAR beam from fully penetrating the vegetation canopy in and around residential areas. Using discriminant analysis, we grouped potential building polygons into building and non-building classes using the point densities of ground, unclassified, and building points. Our technique was 95% accurate at distinguishing buildings from non-buildings. Therefore, we recommend its use in any locale where distinguishing buildings from surrounding vegetation may be affected by the proximity of dense vegetation to buildings.

We examined the emergence behavior of spot‐tailed earless lizards (STEL; Holbrookia lacerata and H. subcaudalis). Using controlled laboratory and seminatural experiments, we evaluated the effects of UV light, visible light, temperature, and prey activity on STEL emergence timing. Our results revealed that the combination of UV and visible light was the primary trigger for STEL emergence, aligning with peak light intensity and suggesting a physiological adaptation mediated through the parietal eye. In addition, the median time of emergence was 5 min after the initiation of LED and UV lights regardless of the time of day. Peak STEL activity occurred between 14:01 and 16:00 h with nearly 50% of STEL aboveground. This delayed emergence after sunrise allows for rapid thermoregulation, minimizing basking time while reducing predation risk by avoiding periods of peak predator (e.g., birds of prey, diurnal snakes) activity, which typically occurs during early morning and late afternoon hours, which is characteristic of arid systems. Moreover, the timing likely optimizes vitamin D3 synthesis, crucial for metabolic health, and minimizes energy expenditure associated with prolonged thermoregulation. STEL's emergence patterns contrast with sympatric species, typically occurring during midday rather than early morning or late evening hours, suggesting a reliance on unique diel niches. Little is known about STEL's ecology, particularly regarding their diel niche and activity patterns, which likely play a crucial adaptive role in species survival and success. Our findings demonstrate the importance of habitat‐specific light regimes in shaping the behaviors of reptiles and provide a model for understanding adaptive strategies in light‐sensitive species. As habitat degradation and climate change alter light and thermal environments, these behaviors may be disrupted, emphasizing the need for conservation practices that preserve open, sunlit habitats. This study contributes to our understanding of the ecological adaptations of reptiles and informs conservation strategies for species in arid and semiarid ecosystems. Our results of spot‐tailed earless lizards (STEL) light‐dependent emergence behavior not only illustrate adaptation to specific environmental cues, but also offer insights into the resilience and adaptability of reptiles inhabiting arid and semiarid ecosystems. Specifically, our study demonstrates how STEL's reliance on UV light shapes their behavior and suggests that their diel niche specialization reduces predation risks and interspecific competition.

Plant species richness is an important property of ecosystems that is altered by grazing. In a semiarid environment, we tested the hypotheses that (1) small‐scale herbaceous plant species richness declines linearly with increasing grazing intensity by large ungulates, (2) precipitation and percent sand interact with grazing intensity, and (3) response of herbaceous plant species richness to increasing intensity of ungulate grazing varies with patch productivity. During January–March 2012, we randomly allocated 50, 1.5‐m × 1.5‐m grazing exclosures within each of six 2500 ha study sites across South Texas, USA. We counted the number of herbaceous plant species and harvested vegetation in 0.25‐m2 plots within exclosures (ungrazed control plots) and in the grazed area outside the exclosures (grazed treatment plots) during October–November 2012–2019. We estimated percent use (grazing intensity) based on the difference in herbaceous plant standing crop between control plots and treatment plots. We selected the negative binomial regression model that best explained the relationship between grazing intensity and herbaceous plant species richness using the Schwarz‐Bayesian information criterion. After accounting for the positive effect of precipitation and percent sand on herbaceous plant species richness, species richness/0.25 m2 increased slightly from 0% to 30% grazing intensity and then declined with increasing grazing intensity. Linear and quadratic responses of herbaceous plant species richness to increasing grazing intensity were greater for the least productive patches (<15.7 g/0.25 m2) than for productive patches (≥15.7 g/0.25 m2). Our results followed the pattern predicted by the intermediate disturbance hypothesis model for the effect of grazing intensity on small‐scale herbaceous plant species richness. We examined the relationship between intensity of grazing by large ungulates and herbaceous plant species richness in a semiarid environment. Species richness increased with increasing grazing intensity up to around 30% utilization of herbaceous vegetation. Response to grazing followed a hump‐backed relationship with herbaceous plant species richness declining with increasing intensity of grazing exceeding 30% utilization.

The application of unmanned aerial vehicles (UAVs) in the monitoring and management of rangelands has exponentially increased in recent years due to the miniaturization of sensors, ability to capture imagery with high spatial resolution, lower altitude platforms, and the ease of flying UAVs in remote environments. The aim of this research was to develop a method to estimate forage mass in rangelands using high-resolution imagery derived from the UAV using a South Texas pasture as a pilot site. The specific objectives of this research were to (1) evaluate the feasibility of quantifying forage mass in semi-arid rangelands using a double sampling technique with high-resolution imagery and (2) to compare the effect of altitude on forage mass estimation. Orthoimagery and digital surface models (DSM) with a resolution <1.5 cm were acquired with an UAV at altitudes of 30, 40, and 50 m above ground level (AGL) in Duval County, Texas. Field forage mass data were regressed on volumes obtained from a DSM. Our results show that volumes estimated with UAV data and forage mass as measured in the field have a significant relationship at all flight altitudes with best results at 30-m AGL (r2 = 0.65) and 50-m AGL (r2 = 0.63). Furthermore, the use of UAVs would allow one to collect a large number of samples using a non-destructive method to estimate available forage for grazing animals.

Optimal collection and preservation protocols for fecal DNA genotyping are not firmly established. We evaluated 3 factors that influence microsatellite genotyping success of fecal DNA extracted from coyote (Canis latrans) scats: 1) age of scat, 2) preservative, and 3) diet content. We quantified genotyping success by comparing rates of allelic dropout, false alleles, and failed amplifications among consensus genotypes. We used a panel of 6 microsatellite loci to genotype 20 scat samples, each of which was subjected to 3 age (1 day, 5 days, and 10 days post-deposition) and 3 preservation (DET buffer, 95% ethanol [EtOH], and lysis buffer) treatments. Both sample age and storage buffer had a significant effect on success and reliability. Ethanol and DET buffer preserved fecal samples with similar efficiency, and both were superior to lysis buffer. Our analysis of DNA degradation rates revealed that samples collected as early as 5 days of age yielded DNA that was highly degraded relative to samples collected on day 1. We tested the influence of dietary remains on microsatellite genotyping by using scat samples consisting predominantly of insect prey (n = 5), mammalian prey (n = 9), or the remains of juniper (Juniperus spp.) berries (n = 6) and compared EtOH and DET buffer preservation efficacy. We observed a significant interaction effect between storage buffer and diet for the probability of a false allele in a polymerase chain reaction (PCR), suggesting that the optimal preservation technique depended on the food remains comprising the scat. Scats comprised of juniper berry remains were more reliably genotyped when preserved in DET than EtOH. Mammalian preybased scats were more reliable when stored in EtOH than DET buffer. Insect-predominant scats were preserved in EtOH and DET buffer with similar efficiency. Although accurate and reliable results can be obtained from scats collected at ≥5 days of age, we suggest sampling design to include collection of scats <5 days of age to minimize field and laboratory expenses. We suggest EtOH preservation for scats of obligate carnivores and of facultative carnivores with a diet consisting primarily of mammals. We suggest DET buffer preservation for animals with a diet consisting of plant-derived foods. Lysis buffer protocols that we employed should not be used for fecal DNA preservation.

American alligators ( ) are maintained in zoos, aquaria, and farms for educational, research, and production purposes. The standard of veterinary medical care and welfare for captive reptiles requires managing pain and discomfort under conditions deemed painful in mammals. While analgesic efficacy and pharmacokinetic data for several reptile species are published, data with respect to analgesic efficacy in crocodilians are clearly lacking. The objective of this study was to determine the analgesic efficacy of hydromorphone in alligators. Female American alligators (  = 9; 57 months of age) were exposed to mechanical noxious stimuli at multiple anatomic sites using von Frey filaments ranging in size from 1.65 to 6.65 grams-force, and their behavioral reactions recorded. In order to evaluate analgesic efficacy, hydromorphone (0.5 mg/kg SC) was administered in the axillary region to the same alligators and the mechanical noxious stimuli were repeated and behaviors recorded. Administration of hydromorphone contributed to a range from 62 to 92% reduced avoidance reactions to mechanical noxious stimuli for two anatomic sites (i.e., naris and lateral mandible, respectively). Alligators did not appear to experience clinically relevant respiratory depression, hypothermia, or other adverse reactions. Therefore, hydromorphone shows promise as an analgesic option to be administered under painful conditions in American alligators.