We studied the diet and foraging behavior of bobcats (Lynx rufus) in the Chihuahuan Desert, Mexico, from 2005–2007 to test if bobcats will select energetically profitable prey, regardless of their relative abundance. We estimated frequency of occurrence and percentage of occurrence for species of prey in the diet through analysis of scats (n = 117) and evaluated selection of prey by comparing availability against consumption, based on biomass and number of prey consumed as represented in scats. Bobcats consumed a wide variety of prey, but rodents and lagomorphs dominated the diet. Species of prey were not consumed according to availability; combined lagomorphs had the highest probability of being selected based on densities and biomass despite their lower availability. Within lagomorphs, based on their availability, rabbits (Sylvilagus audubonii) were selected more often than jackrabbits. By analyzing the availability and biomass of prey against its consumption, we determined that bobcats do not select prey for high availability but act as specialist foragers. Foraging theory provides the best explanation of dietary selection by bobcats in our study area.

To investigate dietary differences in two coexisting competing predators, we determined prey consumed by bobcats (Lynx rufus) and coyotes (Canis latrans) from scats in the Izta-Popo National Park, central Mexico. Use of prey by bobcats and coyotes showed a Pianka's index of overlap of 0.94, much higher than in other studies of the diet of these two species. Diets of bobcats were comprised primarily of eastern cottontail (Sylvilagus floridanus, 33.7%), rodents (22.7%), Mexican cottontail (S. cunicularius, 13.1%), the endemic and endangered volcano rabbit (Romerolagus diazi, 12.5%), Merriam's pocket gopher (Pappogeomys merriani, 9.3%), and long-tailed partridge (Dendrortyx macroura, 1.4%). Prey used by coyotes included primarily eastern cottontail (43.8%), rodents (15.7%), Mexican cottontail (12.0%), Merriam's pocket gopher (6.4%), and volcano rabbit (5.5%).

We evaluated several factors that potentially influence where the federally endangered American burying beetle (Nicrophorus americanus) is most abundant. We investigated associations of numbers of beetles and measures of abundance of vertebrates at Camp Gruber Military Reservation, Oklahoma. During summer 2003, 87 sites were surveyed for beetles (baited pitfall-traps), birds (modified point-count transects), and mammals (Museum Special snap-traps and rat traps), finding significant rank correlations of number of beetles with number of species of birds, number of individual birds, and biomass of birds but not with similar measures for mammals. Combined biomass of birds and mammals was significantly associated with number of beetles. Path analysis, considering four possible direct influences of measures for vertebrates on beetles, indicated number of beetles was directly and positively affected by biomass of birds and biomass of mammals and inversely by number of individual mammals, while number of individual birds was unrelated to numbers of beetles. Beetles tended to be at sites with fewer but larger mammals that were ≤200 g. Path analysis provided the most informative assessment in that variables potentially influencing beetle numbers were considered simultaneously. While results for Camp Gruber were not identical to those of a similar study at Fort Chaffee, Arkansas, both indicated N. americanus was more likely in places frequented by vertebrates. The association might be due to beetles being attracted to places with more vertebrates because carcasses likely were more abundant; alternatively, suitable environmental conditions may attract vertebrates and N. americanus. Also, beetles may have increased reproductive success at such sites. Lack of covariation of numbers of avian and mammalian species at sites strengthens the supposition of beetles being attracted to sites because of birds and mammals found there.

We designed a remote-camera survey to study how the expansion of California State Route 71 (CA-71) and implementation of connectivity mitigation affected the use of underpasses by large mammals in southern California. Based on detections by cameras, the use of underpasses by bobcats (Lynx rufus) was higher within the area of expansion and mitigation after construction than before, but there was no difference in use of underpasses in the impact zone compared to the control zone before or after construction. Use of underpasses by coyotes (Canis latrans) was higher in the control zone than in the impact zone, but there was no difference in use before and after construction. Small numbers of detections of mule deer (Odocoileus hemionus) at only a few underpasses precluded comparison between control and impact zones. However, a comparison of use before and after construction revealed that use of underpasses by mule deer was slightly higher post-construction. We cannot fully attribute increased detections post-construction to mitigative efforts, because other factors, such as availability of habitat, urbanization, or demography, also may have influenced use of underpasses along CA-71. Nonetheless, even with the expansion of the freeway and subsequent increase in volume of traffic, mitigative structures along CA-71 did allow for continued movement and, hence, connectivity across the roadway for large mammals.

We evaluated nest-site selection in a reintroduced population of Macrochelys temminckii at two locations in southeastern Oklahoma by comparing mean values of variables characterizing microhabitat at nest-sites and random sites. We also analyzed the spatial distribution of nests using a computer randomization procedure. The spatial distribution of nests did not differ significantly from random. However, females nested in areas with significantly greater water depths 2 m from the shoreline and significantly less ground cover compared to random sites. Areas with little ground cover might indicate sites with thermal characteristics appropriate for incubation of eggs laid by M. temminckii, and greater water depth may provide cover for females prior to nesting. The discovery of nest-sites at the same location in consecutive years suggests that some female M. temminckii might return to the same place to nest repeatedly, but further study is required to confirm whether this species exhibits nest-site fidelity.

We compared plants used as sites for nests and survival of nests of black-chinned hummingbirds (Archilochus alexandri) along two rivers in New Mexico. Along the free-flowing Gila River which was dominated by native plants, most nests were constructed in boxelder (Acer negundo). Along the flow-restricted Middle Rio Grande which was dominated by nonnative plants, most nests were constructed in nonnative plants such as Russian olive (Elaeagnus angustifolia) and saltcedar (Tamarix). Mean nest height varied among species of plants used as nesting sites but was about 4 m at each study area. Logistic exposure-estimates of survival of nests were considerably higher along the Middle Rio Grande (52%) than the along the Gila River (23%). Survival of nests was influenced by nest height and species of plant used as nesting site, with survival rates of nests greatest at mean heights in Russian olive and saltcedar. Our results highlight considerable variation in nesting characteristics between two study areas and show that subcanopy nest-sites are essential components of productive habitat for this species.

We studied associations with winter habitat for seven species of birds, one species-group (eastern and western meadowlarks combined), and total sparrows at seven sites in the semidesert and plains grasslands of southeastern Arizona from 1999–2001, sampling with mist-nets and survey-transects. We measured structure and composition of vegetation, assessing vegetative differences among sites, and modeled associations between indices of avian abundance and six vegetative variables using generalized linear models. For all vegetative variables, there were significant differences among sites. Numbers of northern harriers (Circus cyaneus) were positively associated with total number of sparrows. Indices of abundance for individual species of birds were statistically correlated with various measures of structure and composition of vegetation. In particular, grasshopper (Ammodramus savannarum) and vesper (Pooecetes gramineus) sparrows were negatively associated with amount of bare ground; horned larks (Eremophila alpestris) were negatively associated with vertical grass density; Baird's sparrows (A. bairdii) were negatively associated with shrub density; meadowlarks (Sturnella magna and S. neglecta combined) were positively associated with native grass. Our results suggest that these species would benefit from management of habitat that affects the vegetative characteristics associated with their abundance.

We examined the distribution and co-occurrence of the exotic digenetic trematode Centrocestus formosanus, its exotic intermediate host the red-rim melania snail Melanoides tuberculatus, and rates of infection of fish in 10 spring systems throughout western Texas during 1999 and 2011. Four of the spring systems (East Sandia Springs, Independence Creek, Big Bend National Park Refugium Pond, and Clear Creek) did not contain red-rim melania snails in 1999 and 2011. Four spring systems that were populated with snails (San Felipe Creek, San Solomon Springs, Phantom Lake, and Diamond Y Springs) contained the trematode and were positive for branchial infection in fish except Diamond Y Springs which contained uninfected snails and fish. Since 1999, two additional spring systems, Pinto Creek and Devils River, contained the trematode. We found a high prevalence of branchial infection for fish collected regardless of species. Seventeen of the 21 species of fish collected from the spring systems were positive for infection by trematodes. On average, the most infected genera were Micropterus and Lepomis followed in decreasing order by Etheostoma, Dionda, Astyanax, Cichlasoma, Notropis, Cyprinella, Gambusia, Ictalurus, and Hypostomus. Seven state-listed or federally listed species we collected had a relatively high percentage (mean = 52%) of developing metacercarial cysts except E. grahami (mean = 14%). Our laboratory study suggests that, for Gambusia, rates of infection by trematodes are species–specific with G. affinis having significantly more cysts than did G. nobilis and G. gaigei. Our work extended the documented range of red-rim melania snails and C. formosanus in Texas.

Multivariate analyses of seven meristic characters from 257 specimens of Aspidoscelis hyperythra from Baja California Peninsula, Mexico, revealed pan-peninsular patterns of morphological variation. We observed a significant morphological shift between southern and northern populations at the Isthmus of La Paz, the location of a Pliocene trans-peninsular seaway that could have separated the two groups for a substantial length of time. However, we did not observe fixed character states, such as number of pale dorsal stripes, diagnostic of southern and northern populations. The co-occurrence in local populations of variable numbers of individuals with five, six, or seven stripes makes peninsular A. hyperythra an unusual member of the A. deppii species-group, where number of stripes is consistent in local populations. Samples from the Cape Region were statistically homogeneous based on the characters analyzed, but samples from the latitudinally expansive northern area revealed a pattern of similarities and significant differences unrelated to distances between localities.

Annual monsoons produce violent thunderstorms in the southwestern USA and can result in significant overland flow and flash floods in stream channels, washing many invertebrates into the streams. We identified >140 taxa of terrestrial invertebrates in samples collected from receding flows in ephemeral stream channels after monsoon-related flash floods at 14 sites in Arizona and New Mexico. Relative to the number of aquatic organisms, proportions of terrestrial individuals and terrestrial taxa were initially high but decreased over time. The initial flush of water during the flows appeared to be very destructive, such that the average organism was 40% intact 24 h after waters began to recede. On the second day, the average individual was 90% intact, but the proportion of intact organisms declined over time. These results suggest high inputs of terrestrial invertebrates to these stream ecosystems during the monsoon.

We hypothesized that vegetative changes would be visible in a series of repeat photographs (1948–2010) taken at the edge of the Bandera Lava Flow, New Mexico, while inventory of trees and data on age would reveal minimal structural and compositional changes at a woodland site on the inaccessible interior of the lava flow. We concluded that the insular qualities of the volcanic badlands resulted in minimal changes at the interior site during the twentieth and early twenty-first centuries, while noticeable vegetative changes occurred at the periphery of the Bandera Lava Flow during the same period. Vegetative changes at the lava-substrate interface could be linked to variability in use of land, management of fire, and precipitation.

During a multi-year study of the rare Blair's fencing crayfish (Faxonella blairi Hayes and Reimer), we made 87 collections in 10 counties throughout the West Gulf Coastal Plain of southwestern Arkansas. Intensive searches throughout these counties revealed the presence of 36 new populations of F. blairi in Little River, Miller, and Sevier counties. In each of these counties, F. blairi was found to be a locally abundant crayfish. New county records from museum collections were documented for Columbia and Howard counties, Arkansas, and Cass County, Texas. Additionally, we surveyed genetic variation in F. blairi and found them to be a monophyletic group with a sister relationship to Faxonella clypeata but with clear genetic distinctiveness from this sister taxon. There was modest genetic variation within Arkansas, and this genetic variation was greater than that across Arkansas, Oklahoma, and Texas for F. blairi. Faxonella blairi should be considered as currently stable due to its more widespread distribution than previously believed and general abundance throughout its range in southwestern Arkansas.

Meristic morphological variation among samples of A. neomexicana, A. sexlineata viridis, and their hybrids from Ute and Conchas lakes, New Mexico, was assessed to determine if evidence of separate introductions resided in differences in A. neomexicana between the two localities. However, there were no significant differences between samples of A. neomexicana (and between samples of A. sexlineata viridis) based on multivariate statistical analyses of eight meristic characters. Paradoxically, hybrids from the two localities were significantly different in principal components 1 and 2 and in pigmentation. Hybrids from Ute Lake were paler than hybrids from Conchas Lake and A. neomexicana from both localities. All hybrids could be visually distinguished from A. neomexicana by the absence of thin transverse gray bands on the ventral surface of the tail and closer paravertebral stripes.

We surveyed the small mammals of remnant mixed hardwood-coniferous cloud forest at elevations ranging from 2,100–2,300 m in the Chelemhá Cloud Forest Reserve, Alta Verapaz, Guatemala. Removal-trapping using a combination of live traps, snap traps, and pitfall traps for 6 days in January 2007 resulted in 175 captures of 15 species of marsupials, shrews, and rodents. This diversity of small mammals is the highest that we have recorded from a single locality of the 10 visited during eight field seasons in the highlands of Guatemala. Based on captures, the most abundant species in the community of small mammals is Peromyscus grandis (n = 50), followed by Handleyomys rhabdops (n = 27), Heteromys desmarestianus (n = 18), Reithrodontomys mexicanus (n = 17), Handleyomys saturatior (n = 16), Sorex veraepacis (n = 15), and Scotinomys teguina (n = 13). The remaining eight species were represented by one to five individuals.

Limited woodland habitat may influence birds during migration throughout the short-grass prairie of eastern New Mexico and affect their use of habitats. Therefore, we examined the differential habitat use by songbirds during spring and fall migration to determine what strategy migrants use as they move through eastern New Mexico. Our objectives were to determine patterns of species richness, guild richness, and species abundance in wooded habitats in eastern New Mexico during spring and fall migration. We conducted point-counts in wooded habitats in eastern New Mexico within three types of habitat: patches of natural cottonwood (Populus) and elm (Ulmus); patches of invasive tamarisk (Tamarix ramosissima); residential wooded habitats dominated by cottonwoods and elms. Patterns between seasons were nearly identical. Total richness and richness of Nearctic-Neotropical migrants were significantly higher in natural cottonwood patches compared to other habitats. Overall, stands of tamarisk had limited value to any guild. For individual species, insectivores and Nearctic-Neotropic migrants were more commonly encountered in cottonwood draws. However, several migratory species used all three habitats with no significant difference. Information from this study will be valuable to elucidate differences among species and habitats during migration to help in overall conservation of songbirds.

We hypothesized that, if agave (Agave) were used by desert ungulates as a source of moisture, they would be used more during drought than during periods with average or above-average rainfall. From 2004–2012, we counted the number of stalks of agave used by Nelson's bighorn sheep (Ovis canadensis nelsoni) in 10.3 ha in Deep Canyon, Santa Rosa Mountains, California. During years of average or above-average rainfall, bighorn sheep consumed <3% of available stalks of agave. During years with rainfall below average, bighorn sheep consumed from 20–53% of available stalks of agave, thus supporting our hypothesis.

Based on site-visits over the past several years to Conner Cave in Major County, Oklahoma, it appears that the large population of Brazilian free-tailed bats that historically used the cave as a maternity site has abandoned the cave. This was one of the northernmost maternity caves in the Great Plains. Previous estimates of the size of the population were several hundred thousand.

To determine if the strategy of spawning in saucer-like depressions is obligate or facultative for longfin dace (Agosia chrysogaster), we collected adults from four sites in the upper Gila River (southwestern New Mexico), stocked them in separate outdoor stream-mesocosms lined with cobble substrate, and made daily observations for the presence of saucer-nests and hatched larvae. Larvae were observed from three of the four mesocosms and emerged at temperatures ranging from 19.2–24.0°C. The absence of saucer-nests in all mesocosms throughout the study indicates that longfin dace can spawn over cobble substrate and have larvae hatch successfully, suggesting that longfin dace can use an alternate spawning strategy when sand substrate is not available for construction of saucer-nests.

We examined aspects of natural history and ecology of the black-chested spiny-tailed iguana, Ctenosaura melanosterna, on Cayo Cochino Menor, Honduras, over 6 years to provide baseline data to assist in management of this critically endangered species. Size of territory is resource-dependent, and the species seems to prefer habitats with open canopy. Mating occurred between March and June, with emergence of hatchlings from June to August. Ctenosaura melanosterna is an omnivore that feeds on a variety of vegetation, invertebrates, vertebrates, and food-scraps. The threats to this population include predation by Boa constrictor, competition with an increasing population of Iguana iguana, and potential poaching of adults and eggs for food.

Quality of riparian and in-stream habitat, concentrations of ambient stream nitrate and soluble reactive phosphorus, and the diversity and abundance of aquatic macroinvertebrates were measured to characterize riparian and aquatic habitats within and bordering Palenque National Park, Chiapas, Mexico. Though riparian habitat at the majority of the sites was relatively intact, sites were frequently characterized by high concentrations of soluble reactive phosphorus, suggesting that many of the stream ecosystems around the park were influenced by sewage, agricultural runoff, or both. Abundance of macroinvertebrates decreased with increasing concentrations of nitrate at all sites and diversity of macroinvertebrates increased with increasing riparian and aquatic habitat at most of the sites.

The diets of stoneflies (Perlodidae) and hellgrammites (Corydalidae) from the Gila River, New Mexico, were quantified and compared to diets of three native fishes that also occupy riffle habitats along with stoneflies and hellgrammites: speckled dace (Rhinichthys osculus); longfin dace (Agosia chrysogaster); desert sucker (Catostomus clarkii). The highest overlap occurred among corydalids, desert sucker, and longfin dace, which had diets dominated by amorphous detritus. Speckled dace and perlodids consumed less amorphous detritus, with nymphs of mayflies and larval black flies dominating their respective diets. Our results suggest moderate to high overlap of resources among invertivorous fishes and invertebrates. Although we found high dietary overlap between corydalids and two fishes, it is unclear whether amorphous detritus is a limiting resource that drives competitive interactions.

During spring 2008, 12 empty nests built by verdins (Auriparus flaviceps) were collected from xerophytic scrubland in Baja California Sur, Mexico. Percentages of materials used to build nests (based on mass) were estimated, and the species of trees or shrubs with nests were determined. Trees and shrubs within a 5-m radius of the plant with a nest were identified. Material used by verdin for nests was primarily twigs of cape wild-plum (Cyrtocarpa edulis; average 97.6%), an endemic of Baja California Sur.

The false spike (Quadrula mitchelli) is a freshwater bivalve native to central Texas and thought to be extinct until a small population, consisting only of mature adults, was located on the Guadalupe River in 2011. In fall of 2012, we located a small population of the false spike in another section of the Guadalupe River. This population, consisting of adults and juveniles, displayed evidence of successful reproduction and recruitment. We present a description of the physical habitat during low water-flow for this reproducing population of a critically endangered species.

We report an observation of overland dispersal in a flightless aquatic insect during a period of drought-induced stream-drying. We observed an adult giant water bug, Abedus herberti (Hemiptera: Belostomatidae), crawling at 4.6 m/min along a dry stream channel in the Galiuro Mountains, Arizona. We tracked the individual for 130 m and estimate that it moved 240 m from the nearest remaining aquatic habitat. Additionally, we conducted behavioral experiments that confirm that A. herberti can use drying as a cue to initiate movement.

Two instances of rainwater-harvesting behavior by the rock rattlesnake, Crotalus lepidus, are reported. The first observation was of a male collecting water from rain and sleet on 16 February 2008, and the second observation involved another male collecting rainwater on 11 July 2008. The observations took place within a Chihuahuan Desert landscape located in extreme southeastern Hudspeth County, Texas.

We report one new species of macroalgae, Anadyomene stellata, for the Lower Laguna Madre of Texas, and range extensions that have occurred in the past 16 years for this and four other green algae. Anadyomene stellata occurs only as an epiphyte on the red macroalgae, Digenia simplex. Caulerpa sertularioides has not been seen in the Lower Laguna Madre since 1962. It has either been present in cryptic habitats for 50 years near the Lower Laguna Madre or has recently expanded its range again into the Lower Laguna Madre. Ecological consideration of the presence of these species is discussed.

We studied the morphological characters of the keeled earless lizard, Holbrookia propinqua, in Guadalupe County, Texas, near its type locality (Wilson County, Texas) and at the northern extension of its range. Adults of this population were similar to those of other mainland populations but significantly smaller than adults of coastal island populations. Juveniles of the population in Guadalupe County and a coastal population showed no significant differences in size. Tail length of males did not differ among mainland populations but differed significantly from those of the island populations.