Herbivores and omnivores have been shown to regulate their intake of nutrients to a balance that maximizes fitness. Predators were traditionally believed to have less need for dietary regulation than herbivores, given the higher nutritional quality of animal tissue compared to plants. However, some predators, like spiders, may feed on diverse prey that could vary substantially in nutrient content and, hence, their potential quality as food items. This study compared the nutrient intake of Carolina wolf spiders (Hogna carolinensis ) when they fed on cricket frogs (Acris blanchardi) and crickets (Gryllodes sigillatus ). In diet trials, spiders were fasted prior to being offered a frog or cricket for consumption. Then, prey remains and nonconsumed (control) frog and cricket samples were analyzed for lipid, lean tissue, and elemental content. Results show that frogs and crickets vary substantially in the nutrients that they provide to spiders. Frogs offer less lipids but more lean tissue compared to crickets. Additionally, spiders consumed a greater mass of micronutrients when feeding on frogs compared to crickets. While some evidence suggests that lipids may be limited for some spider species, frogs may still be beneficial to spiders' diets because they offer an abundance of lean tissue. Future research should examine how environmental and physiological factors influence the nutritional quality of prey for predators.

IntroductionMultifarious selective pressures can interact to affect species’ life history evolution, with predation and thermal exposure as selective pressures for nesting birds. Gray Vireos (Vireo vicinior) seemingly nest on the periphery of their nesting substrate because of lower predation rates, thereby increasing exposure to weather. We explored how nest placement and vegetation structure can be used to account for the increased weather exposure that Gray Vireos experience when nesting on the periphery of the nesting substrate to avoid predation.MethodsFor each Gray Vireo nest, we placed temperature and light data loggers at three locations: at the nest site, at the opposite orientation of the nest within the nesting tree, and at the same orientation of the nest but in an adjacent tree. To measure nest orientation, we recorded the inverse compass azimuth (+/−1°) from the nest toward the trunk of the nesting tree, while accounting for declination. Nest temperatures and light exposure were compared across various dimensions of nest placement.ResultsThe orientation of nests was cooler than the opposite orientation in the mornings and in the late afternoons. When nests were placed in hotter orientations (e.g., south- or west-facing), nests surrounded by more foliage or placed closer to the interior of trees could compensate for the increased exposure.DiscussionOur findings suggest Gray Vireos accounted for the increased thermal exposure that comes from predator avoidance by using secondary dimensions of nest placement. Specifically, nests could be placed in orientations with cooler temperatures or in hotter orientations with greater shade potential. These results highlight how the interactive selection pressures of predation risk and microclimate can be tiered and shape life-history characteristics of birds.

Understanding the array of financial and non-financial decision-making drivers of private landowners with vulnerable cropland for enrolling in the United States Department of Agriculture’s Conservation Reserve Program (CRP) is critical for the success and cost-effectiveness of agricultural policies that aim to create long-term agri-environmental security. Following the underpinnings of the Theory of Planned Behavior, we used Structural Equation Modeling to test the predictive validity and impacts of socio-cognitive variables: attitude, subjective norm, and perceived behavioral control, on landowners’ intent to enroll in CRP. We analyzed mailed survey data of landowners in the western High Plains of the United States, where irrigated agriculture is a major economic activity, and cropland consists of vulnerable wetlands that play a role in recharging the Ogallala Aquifer. Overall, landowners had a positive attitude towards the wetland conservation benefits of CRP enrollment and its benefits of preventing soil erosion and sedimentation. In addition, attitudes, subjective norms, and perceived behavior controls positively influenced landowners’ intentions to (re)enroll in CRP. Among the three predictors, subjective norms had the largest influence. Landowners’ understanding of CRP benefits in improving water quality and availability, and opinions from their neighbors and other landowners were the most significant measured variables affecting their intention to enroll. For enhanced outreach and long-term success, we suggest that policymakers recognize and respond to a range of non-financial motivations to better design programs that represent the conservation benefits of wetlands to leverage their willingness to participate. Furthermore, (re)enrollment acres could be enhanced by understanding local barriers related to landowners’ skills and knowledge and fostering collaboration and coordination among different federal conservation programs in the region.

Cricket Frogs (Acris blanchardi) live about 1 y and undergo development quickly. In addition to relatively quick metamorphosis, as seen in past outdoor studies, active spermatogenesis in juvenile males can be observed as early as 60 d after metamorphosis, and female development (i.e., ovary and oviduct) is notably progressed prior to overwintering. We assessed life-history traits of field caught A. blanchardi over three time points and three Oklahoma locations. We also compared the development of wild A. blanchardi from one location to findings from previous studies using the same site. We captured cohorts of wild A. blanchardi in the fall (i.e., prior to overwintering), spring (i.e., first observation of emergence), and summer (i.e., first observation of active breeding). Besides general growth and development, we assessed gonadal maturation via histopathology. Ovary, oviduct, and testis development significantly varied among seasons; however, variation in testis development among seasons was less pronounced than ovary and oviduct development. Significant among-pond variation was limited to oviduct development. An assessment of field captured A. blanchardi from two previous years indicated significant year-toyear variation in ovary development but not oviduct or testis development. Despite observed differences in gonad development, variations were often predictable and could be potentially attributed to environmental factors (e.g., water temperature). Nonetheless, the results of our study provide specifics of A. blanchardi development that may be useful for future studies that wish to use this native species as an amphibian research model.

In 2016, the annual value of all global crops dependent upon pollination was valued at $ 235–$ 577 billion (US$). Pollination service is threatened by habitat loss, pesticides, and climate change. We collected potential pollinators with blue vane traps in native grasslands, Conservation Reserve Program (CRP) lands, and cropland (land use), and their embedded playa wetlands (land type) in the Southern High Plains of Texas (SHP). We collected vegetation data that included floral cover, floral diversity, native grass cover, introduced grass cover, canopy gap, and duff cover. Our objective was to determine if individual vegetation characteristics influenced potential pollinator abundance and richness in addition to land use or land type as a whole. The top model explaining abundance was land use, land type, and floral cover. Floral cover had a positive influence on all land uses. The top model that explained insect richness was land use x floral cover, land type, canopy gap, and duff cover. Floral cover positively influenced insect richness in native grasslands but negatively influenced cropland and CRP richness. Percent of canopy gap had a slight negative influence on insect richness, and duff cover positively influenced richness. Our recommendations to land managers are to protect playas to preserve undisturbed areas and native floral resources and seed all future CRP contracts with floral rich plantings to provide for pollinators over the entire growing season. Our results show that vegetation characteristics shared by all land uses such as floral cover, canopy gap and duff cover influence pollinator abundance and richness. Therefore, conserving playa wetlands and programs such as the CRP have the potential for enhancing pollinator habitat in working landscapes of the SHP of Texas.

Habitat management efforts for multiple species with contrasting habitat requirements can be challenging, particularly on small landscapes where large-scale heterogeneity may not be a viable solution. We sought to utilize derivative functions from species-response curves to identify thresholds along an environmental gradient for two species with differing responses to juniper cover. We estimated percentages of one-seed juniper (Juniperus monosperma) cover around loggerhead shrike (Lanius ludovicianus) and gray vireo (Vireo vicinior) nests in central New Mexico in 2016-2020 to better understand tolerance of juniper expansion for these two species of con-servation concern. Species-response curves were derived from generalized additive mixed-effect models, with year as a random effect and a local regression smoother. Loggerhead shrike nests were more likely to occur in areas without junipers at the 170-m radius spatial scale. Nest-site selection declined as percent juniper cover increased. Gray vireo nests were most likely to be found in areas with approximately 11 % juniper cover at the 100-m radius spatial scale. Derivative functions were used to find juniper percentages where the rate of change in species' response was most negative for loggerhead shrikes and most positive for gray vireos. The rate of change in nest-site selection decreased the fastest at 13 % and increased the fastest at 4 % juniper cover for loggerhead shrike and gray vireo, respectively. These results suggest that maintaining juniper percentages between 4 and 13 % at relatively broad spatial scales would likely increase available nesting habitat both species. We demonstrate how derivative functions can be used to estimate the rate of change of species' response to environmental gra-dients and an application of such thresholds to resolve conflicting habitat management for two species of con-servation concern.

BACKGROUND:The herbicide atrazine has been proposed as a potential endocrine disrupting compound (EDC) for amphibians. Using atrazine concentrations below or at those typically found in surface waters (0.5, 5.0, 50 μg/L), we exposed Acris blanchardi (Blanchard's cricket frog) larvae throughout development until metamorphosis (i.e. Gosner stages 26-45). An additional 50 μg/L treatment (50s μg/L) was utilized where supplemented algae was added to control for indirect atrazine effects from reduced food sources. In addition to atrazine, experimental groups also included a negative control and two positive controls, 17β-estradiol (E2) at 2.3 and 25 μg/L. At 60 days post-metamorphosis, A. blanchardi metamorphs were euthanized for analysis of gross and histopathological development.RESULTS:Atrazine did not significantly influence mortality (mean recovery of 54% across treatments), sex ratio, body mass (BM), snout-vent length (SVL), gonad size, nor gonad development of A. blanchardi. Females exposed to 50s μg/L atrazine had 29% less mass, were 10% shorter, and had a 29% lower mean ovary area (mm2 ) as compared to negative controls, suggesting algae enrichment had a significant negative effect. Males exposed to estradiol (25 μg/L) showed an increased level of oviduct development. Ovary area was also significantly influenced by estradiol treatment at 2.3 and 25 μg/L.CONCLUSION:Overall, estradiol had much less effect than predicted based on other model species (e.g. Xenopus laevis). Development of A. blanchardi, overall, was not affected by long-term exposure to environmentally relevant concentrations of atrazine. However, this species also was largely insensitive to exogenous estradiol in this test system. © 2022 Society of Chemical Industry.

Pinyon jays (Gymnorhinus cyanocephalus) are experiencing range wide population declines primarily in response to habitat degradation. More studies examining pinyon jay nest site selection in pinyon-juniper woodlands would be helpful in determining potential habitat management prescriptions. Therefore, we conducted a nest site selection study in pinyon jay breeding habitat in central New Mexico. We compared size and foliage characteristics of pinyon and juniper trees in 42 17.5-m radius plots around pinyon jay nests to 41 same-sized vegetation plots in random locations using binomial generalized linear models. The strongest model indicated that pinyon jays preferred nesting in areas with fewer dead juniper trees within pinyon-juniper habitats. In contrast to previous studies, pinyon jays tended to nest in juniper-dominated areas as opposed to pinyon-dominated areas, possibly in response to widespread pinyon mortality at the study site. Results suggest that pinyon jays may be able to adapt to climate-related pinyon mortality by shifting to juniper dominated habitat.

Common approaches to estimating habitat quality are habitat suitability indices, which are often subjective. We propose a quantitative definition of habitat quality as the percentage of selected habitat that has a high probability of contributing to population growth. Using this definition, we created a habitat quality index based on spatial projections of habitat selection and survival probabilities, and the interaction of those probability gradients. We used nest-site selection and nest survival of Gray Vireos (Vireo vicinior) to represent habitat selection and survival probabilities of a sensitive life stage that is likely to increase population size. We used data from 173 Gray Vireo nests in central New Mexico to estimate selection and survival probabilities. Generalized linear mixed-effect models (GLMM) and logistic exposure models (LEM) were used to estimate nest-site selection and daily nest survival, respectively. We projected top-ranked GLMM and LEM models in a geographic information system (GIS) to spatially display relative probabilities of selection and survival. We converted these continuous probabilities into binary rasters representing high and low selection and survival. Multiplying these two rasters in ArcGIS provided us with a raster of four categories: areas with i) low selection and low survival, ii) low selection and high survival, iii) high selection and low survival, and iv) high selection and high survival. We determined the spatial area of each category and calculated percentage of selected habitat where survival was likely to occur, which we termed a habitat quality index (HQI). At our study site, Gray Vireos had a HQI of 0.85, suggesting that approximately 85% of the highly selected habitat had a high probability of contributing to Gray Vireo population growth through nest survival, and that few ecological traps exist in this landscape. These methods provide a quantifiable, continuous index of habitat quality, with spatial projections of potential ecological trap locations.

ABSTRACT Morelet’s crocodile (Crocodylus moreletii) and hybrid crocodiles (C. moreletii × acutus) are mound-nesting crocodilians found in the lowlands of northern and southern Belize, respectively. Nests of both crocodilians consist of large mounds of soil, vegetation, leaf litter, and in some cases sand. We here report on the fauna associated with nest mounds of C. moreletii and C. moreletii × acutus, and describe the associations between crocodiles and commensal fauna. Our data were collected during various ecological studies conducted from 1992 through 2000, and we examined 138 active (containing eggs) nests of C. moreletii and 11 active nests of C. moreletii × acutus. We noted the occurrence of at least 14 species of fauna associated with 45 (32.6%) C. moreletii and three (27.2%) C. moreletii × acutus nests. Nest-associated fauna included ants, bees, termites, turtles, squamates, birds, and mammals. Associations included five species dwelling within crocodile nest mounds, four species that deposited eggs in crocodile nest mounds, and five species nesting in close proximity to crocodile nests. Nest-associated fauna presumably benefit from the protection afforded by nest attendance and aggressive defence behaviour of female crocodiles, although these benefits have yet to be empirically established.

Understanding the interactions between behavior and habitat characteristics can have important implications for species of conservation concern. Gray vireos ( Vireo vicinior ) are one example of a species of conservation concern that is understudied in terms of nest survival probabilities and the habitat characteristics that influence them. Our objective was to determine if habitat features such as juniper density, juniper foliage density, or tree height influence nest survival probabilities, and if gray vireo nest placement can mitigate habitat risks. Based on previous work, we expected daily nest survival probabilities to be associated with nest height and surrounding vegetation. We monitored 89 nests in central New Mexico from 2016–2018 to estimate daily nest survival probabilities. We compared variation in nest placement, nest tree characteristics, and surrounding vegetation between failed and successful nests using logistic exposure models and Akaike Information Criteria. Daily and cumulative nest survival probability were 0.983 (95% CI [0.973–0.989]) and 0.575 (95% CI [0.444–0.702]), respectively. Top models predicting nest survival included a negative interaction between nest-tree foliage density and the distance of the nest from the edge of the nesting tree. This suggests that gray vireos can mitigate risks associated with low nest concealment by nesting closer to the interior of the nesting tree.

A developmental toxicity testing design was evaluated for larval and post-metamorphic Blanchard's cricket frogs (Acris blanchardi) raised in outdoor enclosures. Larvae were chronically exposed to 17β-estradiol (0.0-2.3 μg/L E2) from free swimming (Gosner stage 26) until metamorphosis. Juvenile frogs were allowed to mature within the enclosures for 60 days to assess effects of larval exposure on development, including body mass, snout-vent length (SVL), sex ratio, gonad size, and gonadal histopathology. Forty-eight percent of the initial 600 animals were recovered at the end of the study. Recovery was not influenced by E2 exposure, but larval losses were negatively impacted by unusually high spring rain events that flooded some larval tanks, and heat-related mortality of late stage larvae during summer. All surviving larvae completed metamorphosis within an average of 47 days. Overall, E2 exposure did not influence sex ratio, or the body mass, SVL, or gonad size of either males or females. Development of testes was not influenced by E2 exposure, but oviduct development in males was 4.5-fold greater in the highest treatment. Oviduct and ovary development in females exposed to the two highest E2 treatments were half that of control females. Although not treatment related and despite ad-lib feeding, variation in terminal body mass and SVL within enclosures was pronounced, with minimum - maximum differences ranging from 207 to 1442 mg for body mass and 1 mm to 15 mm for SVL. This design allowed us to assess the effects of larval exposure to a contaminant on post-metamorphic development of a native amphibian in a semirealistic field environment. With modifications to decrease flooding or overheating, this enclosure design and species is a good test system for assessing contaminant effects on development of an amphibian from early larval stages through reproductive maturity.

Fish and aquatic amphibians possess neuromasts on the surface of their body that constitute the lateral line, a sensory system used to detect water displacement. Copper is known to inactivate the neuromast organs of this system. Copper-induced neuromast loss in African clawed frogs, Xenopus laevis, was examined by exposing Nieuwkoop-Faber stage 54–55 larvae to copper concentrations of 0, 100, 200, 300, and 400 µg/L for 96 h, followed by an examination of neuromast counts, staining intensity, and behavioral responses. Neuromasts were counted using a novel imaging method across four different body regions: the whole body, partial body, head, and tail. Neuromast counts showed a decreasing, but nonsignificant, trend across increasing levels of copper exposure. Intensity of neuromast staining showed a stronger concentration-dependent decrease in all four body regions. The decrease in staining intensity, but not neuromast number, may indicate that although neuromasts are still functioning, they have a decreased number of viable hair cells. Potential loss of responsiveness related to neuromast damage was examined via sensitivity to puffs of air at varying distances. We detected little to no difference in response to the air puff stimulus between control tadpoles and tadpoles exposed to 400 µg/L of copper. Neuromasts of X. laevis may be more resistant to copper than those of North American tadpole species, possibly suggesting greater tolerance of the lateral line to environmental stressors in species that maintain this sensory system throughout their lifespan as compared with species that only have the lateral line during the larval period.

Runt (abnormally small) eggs are widely reported in the avian literature, but the few reports available for crocodilians are ambiguous. From 1992 to 2000, we examined 3015 Crocodylus moreletii (Morelet’s Crocodile) eggs from 117 nests in northern Belize; 9 of these eggs met the criterion for runt eggs. Runt eggs occurred at frequencies (per egg and per clutch) comparable to those reported for wild birds, appeared to be deposited in no particular order within the clutch, and were seemingly viable in some cases. Most runt eggs appeared to be associated with small female body size. In comparison to those of birds, crocodilian runt eggs probably impose minimal energetic costs on females because the maternal investment can be partially recouped by consuming those that fail to hatch.

Depressional wetlands in the Great Plains are experiencing watershed alterations that impact the provisioning of important ecosystem services, which are unmonitored on a large scale (Smith et al. 2011). The Natural Resources Conservation Service’s (NRCS) Conservation Effects Assessment Project (CEAP) determines the effects of conservation programs on ecosystem service provisioning across the nation (Tomer et al. 2014). CEAP–Wetlands has focused on the effects of conservation programs and land use on ecosystem service provisioning in areas dominated by different wetland types. The High Plains region (HPR) primarily contains playa wetlands. The dominant land uses are native grassland, cropland, and conservation program land (Brinson and Eckels 2011). Predictive models were developed from CEAP–Wetlands data and can be used to estimate services by identifying playa wetlands and measuring variables required to populate the models (Duriancik et al. 2008). We developed a sampling manual that can be used to remotely classify playa function and ecosystem service provisioning. The manual and models can be used to monitor ecosystem services and inform USDA conservation decisions. Playas are depressional recharge wetlands that exist within western portions of Texas, Oklahoma, and Kansas, western and central Nebraska, the eastern plains of Colorado and New Mexico, and southeast Wyoming (Smith 2003) (figure 1). Playas exist within closed watersheds and receive water only through precipitation and overland flow (Bolen et al. 1989). Playa hydrology is similar among basins, allowing application of CEAP–Wetlands models to estimate service provisioning (Smith et al. 2015). Playas provide ecosystem services including habitat provisioning, floodwater storage, and carbon (C) sequestration (Smith et al. 2011). When cultivation occurs in …

There are many gaps in our understanding of Gray Vireo (Vireo vicinior) life history especially as it relates to nesting ecology. Our objective was to determine habitat features selected by Gray Vireos for nesting to improve management strategies for breeding populations. We searched for Gray Vireo nests on Kirtland Air Force Base in Albuquerque, New Mexico from 2016 to 2017. We estimated Gray Vireo nest-site selection at the tree level, the surrounding vegetation, and at two broader scales corresponding to selection within territories. Nest-site selection was estimated for 99 Gray Vireo nests. For tree-level selection, we compared characteristics of nesting trees with mean characteristics from groups of six randomly selected one-seed junipers (Juniperus monosperma) within a 25-m radius. We also compared overall vegetation characteristics at the 25-m scale for nesting plots and 66 randomly selected plots. Broad-scale cover proportions of nest sites and random points were estimated at 50- and 100-m radius spatial scales using a geographic information system. Gray Vireos selected nesting trees that were taller and wider than other adjacent junipers. Selection of vegetation characteristics surrounding nests showed a similar pattern, where Gray Vireos nested in areas where junipers were taller, wider, and had greater foliage density than was randomly available. Broad-scale analyses suggested that Gray Vireos selected nest sites in areas with higher proportions of junipers at low elevations (< 1954 m), and lower proportions of junipers in higher elevations (> 1954 m); however, juniper proportions at nest sites consistently ranged from 15 to 30% of available cover. Gray Vireos also tended to select areas with less pinyon pine than what was randomly available at the 100-m radius scale. Future management strategies should provide large patches of old-growth juniper to optimize Gray Vireo nesting habitat.

Numerous studies have documented that invertebrate pollinator services are critical to the world economy. Factors including habitat loss and agricultural practices, however, threaten pollinator populations. Many counties in the Southern High Plains were identified as at risk for a shortage of pollination service from wild bees. This region also has one of the highest concentrations of Conservation Reserve Program (CRP) contracts in the US. The CRP is the largest, voluntary, private lands conservation program in the US and was targeted as a program to improve pollinator habitat. Our objective was to determine how the predominant land uses in the SHP (native grassland, CRP, and cropland) affect pollinator abundance and species richness, and more specifically if the CRP can provide quality habitat for pollinators. We also examined how the keystone habitat, playa wetlands, embedded within these land uses contribute to pollinator habitat (land type: uplands vs. wetland). We used blue vane traps placed in playa basins and adjacent uplands to determine Hymenoptera abundance and richness from April to October in 2013 and 2014. The CRP had lower abundance than cropland and native grassland, and generally less richness. Uplands and playa wetlands had little difference in Hymenoptera abundance and richness. Patch size negatively influenced abundance but had a positive influence on richness. The interaction of vegetation height and percent bare ground positively influenced abundance in cropland and native grasslands, and positively influenced richness in all land uses. In the CRP, vegetation height negatively influenced Hymenoptera abundance and percent bare ground had a positive influence. The years sampled in this study were during a severe extended drought; therefore, these results may be reflective of poor floral resources. The CRP has potential to create valuable habitat for pollinators if land managers incorporate a diversity of native grasses and native forbs into plantings to enhance pollinator foraging and nesting habitat.

While puberty is an animal commonality, little is known of its timing or process in crocodylians. Males copulate with an intromittent phallus that has a distinct glans morphology which directly interacts with the female cloaca, putatively effecting effective semen transfer and ultimately increased fecundity. Here we present, during the Morelet's crocodile lifecycle, a well-defined body length (65 cm snout-vent length) inflection point that marks a subsequent increase of phallic glans growth rates. Putatively, this postpubescent growth produces a copulatory-effective phallus. While not as robust of a trend as snout-vent length, this growth inflection concomitantly begins with a body condition index (CI = BM/SVL3 ) between 2.0 and 2.5 and is most distinct above a CI of 2.5. Also, in males, this 65 cm size threshold also aligns with the initiation of more robust growth in caniniform alveoli associated with prominent maxillary and mandibular teeth. This inflection was not observed in females, thus marking a sexual dimorphism that begins to present with the onset of puberty. This bodily manifestation of puberty other than those changes observed in the reproductive tracts is a novel observation for crocodylians and lays a foundation for further study among species of how changing endocrine signaling within sexually maturing males may also influence a broader range of secondary sex characteristics.

The economic value of insect pollination to the world economy is tremendous, and pollination service is critical for our food supply and persistence of native plants. Little data are currently available on pollinator occurrence in the Southern High Plains (SHP) of Texas. Past studies on hybrid cottonseed production in the region documented high abundance of six species of Agapostemon and lower abundance of Diadasia spp., Melissodes spp., and Perdita spp. Historical records indicated the presence of Bombus fraternus and B. pensylvanicus which now have Endangered and Vulnerable IUCN status respectively. In 2013 and 2014, we used blue vane traps and targeted netting to collect insect pollinators and anthophiles on the three dominant land uses in the region; cropland, Conservation Reserve Program (CRP), and native grasslands. With capture methods combined, we collected 74,215 insect specimens; 63% of the specimens were Hymenoptera (289 taxa), 28.61% were Coleoptera (150 taxa), 4.48% were Diptera (115 taxa), 2.34% were Lepidoptera (60 taxa), and 1.61% were of other orders (15 taxa). Our capture included all previously documented bee genera, but we did not detect B. fraternus. Studies support that blue vane traps are an effective method of trapping bees and our results demonstrated that they are also effective in attracting some families of anthophilous Coleoptera and Diptera. However, we captured several species of Hymenoptera, Diptera, and Lepidoptera with aerial nets that we did not capture in blue vane traps. This study documents pollinator and anthophile species present in a highly altered landscape and is the most comprehensive list of pollinators and anthophiles in this region to date.