Suitability of containerized toxicant to control Solenopsis invicta (Hymenoptera: Formicidae) threatening cave species in Bexar County, Texas

Several protected troglobitic invertebrate species are known to occur in caves on Joint Base San Antonio-Camp Bullis, Bexar County, Texas, United States. The United States Fish and Wildlife Service (USFWS) identified red-imported fire ant Solenopsis invicta (hereafter RIFA) (Buren 1972) as the primary threat to cave species' nutrient sources, cave crickets, Ceuthophilus secretus (Scudder 1894). Per the service's recommendations, Joint Base San Antonio-Camp Bullis currently implements boiling water mound injections with digging for RIFA control. However, treatment effectiveness is highly variable and largely dependent on the time of day, weather, and personnel diligence. Toxicants have been used for RIFA treatment throughout the world, but concerns exist that traditional applications of toxicant bait around caves might be accessible and inadvertently affect nontarget arthropods, including cricket populations. To mitigate this accessibility, physically limiting access to the toxicant from crickets may be an option. Our objectives were to (i) compare and evaluate the effectiveness of Amdro (Hydramethylnon) and Advion (Indoxacarb) granular baits housed in Ants-No-More Bait Stations (Kness MFG. Inc., Albia, IA) and (ii) evaluate the distance of effectiveness of each bait within a bait station. Ultimately, we observed a 98% reduction in RIFA mound abundance from both baits. Additionally, RIFA mounds within 10 m of the containerized toxicant were reduced by 70%. Our pilot study suggested that Ants-No-More Bait Stations are an effective way to reduce RIFA mounds by 70% if placed 10 m from each other. In practice, this could include bait stations completely covering a particular distance to a cave entrance or fewer bait stations in a ring barrier at a single radial distance to a cave entrance. Containerized toxicants may be a cost-effective and safe RIFA control option around protected cave environments, but further studies are needed to determine potential effects on nontarget arthropods, optimal bait station configuration, and potential effects of biomagnification.

Thermal tolerances of Popenaias popeii (Texas hornshell) and its host fish from the Rio Grande Basin, Texas

Freshwater mussels are particularly sensitive to hydrologic changes, including streamflow and temperature, resulting in global decline. The Devils River in south-central Texas harbors the endangered freshwater mussel Popenaias popeii (Unionidae; Texas hornshell). There is concern that water withdrawals from the underlying aquifer may be negatively impacting this species. To assess this risk, we evaluated upper thermal tolerances (LT05 and LT50) of larvae (glochidia) and juveniles from two sites. After being acclimated to 27 °C, glochidia were subjected to five experimental temperatures (30, 32, 34, 36, and 38 °C) and non-acclimated control (20 °C) for 12-h and 24-h while juveniles were subjected to three experimental temperatures (30, 32, and 36 °C) and non-acclimated control (20 °C) for 96-h. We overlaid tolerance estimates against in situ water temperature and discharge data to evaluate thermal exceedances. Additionally, we reviewed upper thermal tolerances of P. popeii's presumed host fish (Carpiodes carpio, Cyprinellas lutrensis, and Moxostoma congestum) and their congeners. Stream temperatures only occasionally exceeded mussel LT05/50 and fish CLMax/LTMax, likely due to the Devils River's large spring input, highlighting the importance of protecting spring flows. We provide a practical framework for assessing hydrological needs of aquatic ectotherms, including the parasite-host relationship, which can be used to optimize environmental management.

Using a multi‐model ensemble approach to determine biodiversity hotspots with limited occurrence data in understudied areas: An example using freshwater mussels in México

Species distribution models (SDMs) are an increasingly important tool for conservation particularly for difficult‐to‐study locations and with understudied fauna. Our aims were to (1) use SDMs and ensemble SDMs to predict the distribution of freshwater mussels in the Pánuco River Basin in Central México; (2) determine habitat factors shaping freshwater mussel occurrence; and (3) use predicted occupancy across a range of taxa to identify freshwater mussel biodiversity hotspots to guide conservation and management. In the Pánuco River Basin, we modeled the distributions of 11 freshwater mussel species using an ensemble approach, wherein multiple SDM methodologies were combined to create a single ensemble map of predicted occupancy. A total of 621 species‐specific observations at 87 sites were used to create species‐specific ensembles. These predictive species ensembles were then combined to create local diversity hotspot maps. Precipitation during the warmest quarter, elevation, and mean temperature were consistently the most important discriminatory environmental variables among species, whereas land use had limited influence across all taxa. To the best of our knowledge, our study is the first freshwater mussel‐focused research to use an ensemble approach to determine species distribution and predict biodiversity hotspots. Our study can be used to guide not only current conservation efforts but also prioritize areas for future conservation and study.

A model for assessing mammal contribution of Escherichia coli to a Texas floodplain

Context Free-ranging mammals contribute to faecal pollution in United States water bodies. However, research into wildlife impact on water quality is dependent upon unreliable data (e.g. data uncertainty, unknown importance of parameters). Aims Our goal was to determine the potential impacts of common free-ranging mammal species and their management on Escherichia coli in the study floodplain. Our objectives for this research were to construct a model from study area- and literature-derived data, determine important species for E. coli deposition, and conduct sensitivity analyses on model parameters to focus future research efforts. Methods We constructed a model that incorporated parameters for four wildlife species known to contribute E. coli in central Texas: raccoons (Procyon lotor), white-tailed deer (Odocoileus virginianus), Virginia opossums (Didelphis virginiana), and wild pigs (Sus scrofa). These parameters were (1) population density estimates, (2) defaecation rates, (3) defaecation areas, (4) E. coli concentration in faecal material estimates, and (5) E. coli survival. We conducted sensitivity analyses on the model parameters to determine relative importance of each parameter and areas for additional study. Key results We found that adjustment of raccoon and Virginia opossum population densities had higher impacts on E. coli in the floodplain than similar changes in other species across all spatial and seasonal variations. We also found that the changes in E. coli survival, E. coli concentration in raccoon faecal material, and defaecation rates had the highest impacts on E. coli in the floodplain. Conclusions Our sensitivity analyses indicated that the largest impacts to projected E. coli loads were from changes in defaecation rates followed by E. coli concentration in faecal material and E. coli survival. Watershed planners, ranchers, and regulators must be cautioned that faecal deposition patterns are location specific and could significantly impact which species are considered the most important contributors. Implications Although all parameters require more research, we recommend that researchers determine defaecation rates for contributing species due to their relatively large impacts on E. coli in comparison to the other parameters. We also suggest additional research in free-ranging wildlife faecal morphology (form and structure) and area of deposition. Finally, species-specific E. coli survival studies for free-ranging wildlife should be conducted.

Role of free-ranging mammals in the deposition of Escherichia coli into a Texas floodplain

Context The role of wildlife in faecal pollution of water bodies (deposition of Escherichia coli (E. coli)) is not well understood. Current water-quality and land-use planning research largely relies on unreliable wildlife data (e.g. poor sourcing of abundance estimates, population density estimates applied to multiple fundamentally different areas, suspect or insufficiently described data collection techniques) Aims Our goal for the present research was to investigate deposition of E. coli into a floodplain by free-ranging mammals. Objectives of the research were to determine the density of important free-ranging meso- and large mammals in the study area, determine faecal E. coli loads for each species, and evaluate spatial data on species-specific faecal deposition. Methods We conducted our research in south-eastern Texas, USA, on two cattle ranches bisected by Cedar Creek (44-km long). Cedar Creek has elevated E. coli concentrations. We conducted mark–recapture and mark–resight population density estimates (2008/09) for meso- and large mammals in the study areas. We collected faecal samples from all captured wildlife. We also conducted transects through the study area to determine faecal-deposition patterns. Key results We found that raccoons (Procyon lotor), wild pigs (Sus scrofa), Virginia opossums (Didelphis virginiana) and white-tailed deer (Odocoileus virginianus) all had substantial faecal E. coli loads and population densities, thus implying an important role in E. coli deposition into the study floodplain. All species were widely distributed through the floodplain. Conclusions Free-ranging mammals contribute E. coli to floodplains and potentially affect water quality. We determined that four species commonly found in floodplains throughout North America all contributed E. coli to the study floodplain, thus implying mammal E. coli contributions in many locations and this is potentially important for E. coli management. Implications Improved locally specific mammal population estimates and estimates of locally derived E. coli concentration will improve floodplain and water-quality models that often depend on data of various quality. Additionally, our analyses demonstrated the need for continued research into the role of wildlife in E. coli deposition.

Evaluation of euthanasia and trap - neuter - return (TNR) programs in managing free-roaming cat populations

Global estimates of the number of domestic cats (Felis catus) are >400 million. Issues associated with free-roaming cats are of global importance because of animal-welfare and public-health concerns and impacts on native wildlife through predation, competition and disease transmission. In the United States, proposed control solutions for managing urban free-roaming cat populations include euthanasia and trap–neuter–return (TNR) programs. We evaluated control methods using a demographic population model for a 25-year period, with parameters estimated from an unmanaged, free-roaming cat population in Texas. We modelled euthanasia and TNR at 25%, 50% and 75% implementation rates and a 50 : 50 combination of euthanasia and TNR at 25%, 50%, 75% and 100% implementation rates for 0%, 25% and 50% maximum immigration rates. We compared final population size, total number of cats treated and treatment effort relative to population reduction. Population decreases were comparable among euthanasia, TNR and a 50 : 50 combination for all treatment rates when the immigration rate was 0%; however, they were higher for euthanasia at 25% and 50% maximum immigration rates. Euthanasia required higher treatment effort than TNR. Our results indicate that immigration must be prevented and high (>50%) treatment rates implemented to reduce free-roaming cat populations.

Repeatability of a telephone questionnaire on cat-ownership patterns and pet-owner demographics evaluation in a community in Texas, USA

The repeatability of a telephone questionnaire on cat-ownership patterns, demographics and attitudes towards homeless cats in a community was evaluated. Randomly selected households (n=100) within Caldwell, Texas, were included in the study. The response percentage was 84% (100/119) among those contacted and 75% (100/134) among all eligible respondents. Repeatability was measured by administering the same survey twice to the first 100 responding subjects, with an average (range) of 48 (25-64) days between interviews. The survey was initially administered from 6 June to 28 June 2005 and the follow-up survey was administered from 19 July to 11 August 2005. Repeatability for most cat-ownership characteristics was fair to good between the two interviews (kappa 0.47-0.82). Knowledge of companion animals and subject attachment to pet questions had good correlations between the two interviews (rsp 0.52 and 0.60, respectively). Subject-demographic questions had excellent repeatability (kappa 0.66-1.00).

Assessing the influence of field- and GIS-based inquiry on student attitude and conceptual knowledge in an undergraduate ecology lab

Combining field experience with use of information technology has the potential to create a problem-based learning environment that engages learners in authentic scientific inquiry. This study, conducted over a 2-yr period, determined differences in attitudes and conceptual knowledge between students in a field lab and students with combined field and geographic information systems (GIS) experience. All students used radio-telemetry equipment to locate fox squirrels, while one group of students was provided an additional data set in a GIS to visualize and quantify squirrel locations. Pre/postsurveys and tests revealed that attitudes improved in year 1 for both groups of students, but differences were minimal between groups. Attitudes generally declined in year 2 due to a change in the authenticity of the field experience; however, attitudes for students that used GIS declined less than those with field experience only. Conceptual knowledge also increased for both groups in both years. The field-based nature of this lab likely had a greater influence on student attitude and conceptual knowledge than did the use of GIS. Although significant differences were limited, GIS did not negatively impact student attitude or conceptual knowledge but potentially provided other benefits to learners.

Predicting the impacts of future sea-level rise on an endangered lagomorph

Human-induced global climate change presents a unique and difficult challenge to the conservation of biodiversity. Despite increasing attention on global climate change, few studies have assessed the projected impacts of sea-level rise to threatened and endangered species. Therefore, we estimated the impacts of rising sea levels on the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) across its geographic distribution under scenarios of current conditions, low (0.3-m), medium (0.6-m), and high (0.9-m) sea-level rise. We also investigated the impacts of allowing vegetation to migrate upslope and not allowing migration and of two land-use planning decisions (protection and abandonment of human-dominated areas). Not surprisingly, under all simulations we found a general trend of decreasing total potential LKMR habitat with increasing sea-level rise. Not allowing migration and protecting human-dominated areas both tended to decrease potential LKMR habitat compared with allowing migration and abandoning human-dominated areas. In conclusion, conservation strategies at multiple scales need to be implemented in order to reduce the impact of global climate change on biodiversity and endangered species. At the regional level, managers must consider land-use planning needs that take into account the needs of both humans and biodiversity. Finally, at the local scale those agencies that are in charge of endangered species conservation and ecosystem management need to rethink static approaches to conservation or else stand by and watch ecosystems degrade and species go extinct. This can be accomplished by bioclimatic reserve systems where climatically underrepresented areas are included in conservation planning along with the standard concerns of threat, opportunity, connectivity, and viability.

Survey of Raccoons on Key Largo, Florida, USA, for Baylisascaris procyonis

Numbers of the endangered Key Largo woodrat (KLWR; Neotoma floridana smalli) have been declining for at least 25 yr. The raccoon (Procyon lotor) roundworm, Baylisascaris procyonis, has been found to have an adverse effect on the survival of Alleghany woodrats (N. magister). High densities of raccoons can exacerbate this problem by increasing the amount of feces containing viable eggs of B. procyonis available to woodrats. In 2002, 64 fecal samples were collected and examined for eggs of B. procyonis from >32 raccoons within the KLWR's known range on Key Largo, Florida, USA. All samples were negative for eggs of B. procyonis. Raccoon density in this area was approximately 0.62 raccoons/ha. Despite this high density of raccoons, B. procyonis does not appear to be a threat to the KLWR population.

Paratuberculosis in key deer (Odocoileus virginianus clavium)

Paratuberculosis was diagnosed in an endangered Key deer (Odocoileus virginianus clavium) in November 1996. Between 10 April 1997 and 28 September 2000, the Key deer population was monitored for infection with Mycobacterium avium subsp. paratuberculosis by necropsy of available carcasses (n = 170), fecal cultures, and serology. One additional clinically affected Key deer was discovered in July 1998, and M. avium subsp. paratuberculosis was cultured from the feces of one live, asymptomatic deer. The results of this study provided sufficient evidence to consider the Key deer herd infected with M. avium subsp. paratuberculosis at very low prevalence.

Morbidity and mortality factors in key deer (Odocoileus virginianus clavium)

The population health of endangered Key deer (Odocoileus virginianus clavium) was monitored from 10 February 1986 to 28 September 2000 by necropsy of animals that were killed by vehicles, euthanized because of terminal injuries or disease conditions, or found dead. The predominant mortality factor during the period was collision with motor vehicles; however, several infectious diseases were diagnosed, including infections with Arcanobacterium pyogenes, Haemonchus contortus, Salmonella spp., and Mycobacterium avium subsp. paratuberculosis. During the period monitored, the only infectious disease that was thought to have affected population dynamics was haemonchosis. Nevertheless, several of the observed diseases have potential to impact viability of the Key deer population under appropriate environmental conditions.