Isla Rasa in the Gulf of California has been recognized as an important seabird breeding island for more than 150 y. Yet during most of this period, the island suffered human disturbances that severely reduced seabird nesting success. Today, nearly two decades after disturbances ended, Isla Rasa supports about 90% of the global populations of Heermann's gulls (Larus heermanni) and elegant terns (Thalasseus elegans), plus smaller populations of other species. However, the recently available 1856 journals of Italian naturalist Federico Craveri, and the oral traditions of the Comcaac (Seri people), suggest that the array of nesting species has changed. Apparently, California brown pelicans (Pelecanus occidentalis californicus) abandoned Isla Rasa as a breeding site at the onset of disturbances, and terns first colonized it around 1920.

Riparian systems in the western United States provide essential stopover habitat to en-route migrant birds, and there is concern that the invasion and dominance of saltcedar (Tamarix) in many areas may inhibit use by some species. However, evidence from recent studies is challenging the widely held belief that invasive plants universally reduce habitat quality. Moreover, where many studies have compared avian use of riparian habitats dominated by saltcedar with those comprised primarily of native trees, few have investigated how birds use shrub communities, which are becoming more prevalent in western riparian zones because of widespread hydrologic modifications. We compared spring migrant use of 125-m sections of riparian habitat dominated by five different habitat types in southwestern Arizona in 2006 and 2007. We found that migrant abundance, species richness, and community assemblages were all influenced by the composition of riparian vegetation. Habitats completely dominated by saltcedar supported fewer migrants and migrant species than any other habitat type, but the presence of small amounts of native vegetation as a part of the overall riparian plant community greatly bolstered habitat use. Habitats dominated by native shrubs tended to support the greatest total migrant abundance, total species richness, and abundance of many individual species. Our findings suggest that riparian areas dominated by saltcedar are avoided by many western migrant species and have relatively low value as stopover habitat. In places where this species is a predominant component of the riparian plant community, restoration of at least a portion of native riparian vegetation may be effective for encouraging use by stopover migrants.

Because of the nature and process of precipitation, tufa deposits offer the potential to serve as sedimentary signatures of hydrology, climate, ecology, and biodiversity in areas otherwise lacking such historic archives. This study investigated a previously undocumented tufa site located in northwestern Arizona. Field mapping, X-ray diffraction, and thin-section analyses revealed a wedge-shaped deposit of nearly pure calcitic tufa. Leaf and bark molds were identified as closely resembling water birch (Betula occidentalis) and conifer species as well. A dense understory of tubular fossils suggestive of horsetails (Equisetum) and other wetland species were also found. Biotic content, lack of ikaite, and proximity to pluvial lake systems strongly correlate the deposit's age with numerous lacustrine deposits in the region and possibly extend the lake system to the south.

Global climate change is expected to increase the aridity of semiarid landscapes by increasing heat stress and decreasing soil moisture, negatively impacting plant survival, growth, and reproduction and forcing major shifts in plant community composition. To better understand potential vegetation shifts, we investigated how aspect-mediated differences in soil moisture and nitrogen influence tree-grass and tree species coexistence in pinyon-juniper woodlands in the southwestern United States (at the Sevilleta Long Term Ecological Research Station in New Mexico). We measured soil moisture, total mineralized soil nitrogen, grass cover, and woody cover and demography of the two dominant trees—two-needle pinyon pine (Pinus edulis) and one-seeded juniper (Juniperus monosperma)—along 32 transects on north-facing and south-facing slopes. Tree cover was greater on north-facing than on south-facing slopes, reflecting significantly higher soil moisture on northern aspects. Aspect did not affect soil nitrogen or grass cover. Population structure for juniper was influenced by aspect while reproductive output was influenced by aspect in both species, suggesting that differences in drought tolerance between these codominant tree species may be responsible for differences in the utilization of resources in our study area. Our results suggest that soil moisture can affect tree cover and tree-grass coexistence more than does nitrogen. Increasing aridity due to global climate change is likely to decrease woody cover in semiarid landscapes, resulting in systems codominated by grasses and woody species.

Spring fires in tallgrass prairie can create environmental conditions conducive to plant growth in the subsequent growing season. Following fires, burned areas can also be attractive to grazing animals such as bison (Bison bison). Sustained grazing activity within recently burned areas can alter vegetation structure relative to nearby landscape patches that haven't burned recently. In 2007, we collected data on bison grazing activity, vegetation structure, and the growth and reproduction of a perennial forb, Arnoglossum plantagineum, in Oklahoma tallgrass prairie. We compared these variables in landscape patches that had burned in the spring of 2007 to measurements of these variables in adjacent landscape patches that had burned in the spring of 2004 or 2005. Our results demonstrate that bison grazing activity and many vegetation structure variables can differ markedly in landscape patches that differ in their time since fire but are directly adjacent to each other.

Mammals from the state of Guerrero, Mexico, are poorly studied, particularly those from the Balsas River basin, despite the importance of this area as a biogeographical boundary for flora and fauna. To contribute to the knowledge of mammals in this state, we compiled information on geographical distribution, habitat, and reproduction for 41 mammal species from Tlaxmalac in the Balsas River basin in northeastern Guerrero. These represented 26.9% of mammal species known from Guerrero and 8.6% of mammal species from Mexico. Eight species were endemic, comprising 19.5% of species surveyed. Mammals from Tlaxmalac had eight different feeding habits. People from the community use 14 species of mammals as part of their diet, as pets, for medicinal purposes, and other uses. Overall, Tlaxmalac supports a great diversity of small and medium-sized mammals.

We collected Devils River minnow (Dionda diaboli) and other fish, water-quality, and habitat data from 19 sites within the headwaters of Pinto Creek (Kinney County) during 2009–2011. We documented where D. diaboli occurred, its relative abundance, and its fish and habitat associations. Dominant species were Gambusia speciosa (54%) and Astyanax mexicanus (28%). Lepomis made up 5% of the fish captured. Densities of D. diaboli were lower than historical values. The headwaters were disjunct habitats for much of study because of drought. We collected D. diaboli at seven locations: six pools and one run just upstream of one of the pools. All fish were associated with thick Chara and low flow (<0.1 m/s). It is unclear whether our data reflect habitat preference or contraction of this population into the available habitat. By July 2011, our study sites were reduced to two pools; neither had D. diaboli.

Morphometric and molecular data are presented that support the hypothesis that the rare endemic Packera franciscana (San Francisco Peaks groundsel) is hybridizing with another Packera species, Packera werneriifolia, which occurs at a lower elevation on the San Francisco Peaks near Flagstaff, Arizona. The morphological data show that most individuals from Snowslide Spring have an intermediate appearance or look more like P. franciscana, and that certain leaf traits show significant variation among the parental species and hybrids. Our genetic data show that hybrids share alleles with both parental species and suggest that hybridization may be more widespread than the single population at Snowslide Spring. Correlations between the morphology and genetics of these groups may be useful in providing managers with a tool for identifying hybrids without the expense of genetic analysis.

Cave swallows (Petrochelidon fulva) have undergone a dramatic range expansion in the southwestern United States. In south Texas, this has coincided with a concurrent decline in culvert-nesting barn swallows (Hirundo rustica), leading some authors to suggest that colonizing cave swallows negatively impact barn swallows. Here we compare the reproduction of syntopic nesting barn and cave swallows in culverts and under bridges at the northeastern edge of the expanding cave swallow distribution. Cave swallows in northeastern Texas had reproductive success comparable to natural populations further south. Syntopic nesting barn swallows had much-reduced reproductive success when compared with results of studies in this area prior to colonization by cave swallows. Though cave swallows had higher fledging success, this trend was only significant for culvert-nesting birds. Barn swallows nesting under bridges did better than their counterparts in culverts, possibly because of structural differences and their effect on social interactions. These data are consistent with the suggestion that colonization by cave swallows has a negative impact on barn swallows nesting in culverts.

Montane riparian areas across the Sky Island region of the southwestern United States and northwestern Mexico contribute disproportionally to biodiversity at local and regional scales. We explored how composition and structure of vegetation influenced species richness and community composition of songbirds breeding in riparian areas of southern Arizona. We surveyed birds and vegetation during two breeding seasons at 45 stations established across three riparian canyons in two mountain ranges. Species richness of songbirds increased as volume of understory vegetation, density of Arizona sycamore (Platanus wrightii), and density of alligator juniper (Juniperus deppeana) increased; species richness decreased as density of Acacia and Mimosa species increased and oak (Quercus) trees increased. Composition of breeding bird communities was structured along an elevation and vegetation gradient, from open-canopy desert scrub to closed-canopy oak woodlands. Richness and composition of breeding bird communities in these biologically diverse montane riparian canyons were governed by both floristic composition and physical structure of dominant riparian vegetation.

Tornillo Creek, a tributary of the Rio Grande in Texas, United States, has historically been an important nursery and spawning habitat for several native fish species. We examined variation in the seasonal fish assemblages in Tornillo Creek within and between two time periods (1967–1970 vs. 2009–2011), and contemporary fish assemblage–environment associations, in order to understand what environmental factors were associated with seasonal fish abundance and occupancy patterns. Our results indicated that fish assemblages were very different between the two time periods. Contemporary seasonal fish assemblage patterns in Tornillo Creek were less variable than historical assemblages and were linked to several environmental factors including water temperature, stream depth, and current velocity. We suggest that the maintenance of stream flow and connectivity are important for the immigration and emigration of certain riverine fishes in Tornillo Creek and that decreases in stream flow could accelerate the domination of the tolerant species in the creek.

We calculated hatching dates for 2,479 immature mourning doves (Zenaida macroura) captured and banded in a suburban area of Tucson, Arizona, during 2000–2012. Hatching commenced in February and continued into late September. Frequency of hatching peaked during 21–31 May and gradually declined to the end of September. Mourning doves in the Tucson area have hatching distribution similar to those of populations in other parts of the United States. Our data show no measurable differences in length of the mourning dove breeding season among varied locations throughout the United States over a 70-year period.

Bats have been considered efficient seed dispersers of columnar cactus (Isolatocereus dumortieri). However, to date, very little is known about the effect of seed ingestion by bats on seed germination. We carried out some germination assays for seeds of the cactus I. dumortieri obtained directly from fruits and fecal clumps of the endangered lesser long-nosed bat (Leptonycteris yerbabuenae) in a semiarid zone, within the Biosphere Reserve Barranca of Metztitlán in Central México. Additionally, we evaluated seed deposition patterns by bats. We found that 61.7% of the removed seeds were dispersed in fecal clumps, whereas the remaining seeds were spitted as single seeds. We also found that ingestion diminished seed germination by 65%. Under these conditions, seeds deposited individually around the mother plant may be of importance for local restoration and have the function of reforesting the locality, whereas ingested seeds can reach long distances and colonize new areas.

We used thermal imaging to estimate the sizes of the four major Brazilian free-tailed bat (Tadarida brasiliensis) maternity populations in Oklahoma during the summer of 2010 and 2011. The four Oklahoma maternity caves were Merrihew Bat Cave which averaged 66,708 bats, Reed Bat Cave which averaged 165,057 bats, Selman Bat Cave which averaged 54,238 bats, and Vickery Bat Cave which averaged 84,252 bats for all emergences. This study suggests there is a sizable difference in the thermal imaging population size estimates of free-tailed bats at Oklahoma maternity roosts compared to historical estimates using other methods. These differences might be due to the improved accuracy of thermal imaging, or because there is a real decline in bat numbers in Oklahoma, or both.

The diet of a gomphothere (Proboscidea, Gomphotheriidae, Rhynchotherium species) from the Mexican Pliocene was determined using carbon and oxygen stable isotopes relationships in dental enamel. The analyses demonstrated that this individual exclusively fed on C3 plants, similar to some specimens found in Florida, United States.

Prior to 2011, the introduced Mediterranean gecko (Hemidactylus turcicus) was known from 11 of Oklahoma's 77 counties. Following the discovery of a small breeding population in the city of Lawton, Comanche County, Oklahoma, in 2011, we began surveys to determine whether they had become established in the southwestern part of the state. Here we add 11 new county records to their previously described distribution, defining a new western limit for H. turcicus in the state.

We report the first record of the rare carpenter ant (Camponotus microps) from the states of Guanajuato and Querétaro, México. This species was previously known only from the type series from the Chiricahua Mountains of southeastern Arizona, USA. This species is a member of the picipes species complex, and can be easily separated from the similar common Camponotus festinatus, as well as other members of the complex, by the short antennal scapes.

We describe seven instances of kleptoparasitism by the Inca dove (Columbina inca) on the red harvester ant (Pogonomyrmex barbatus) in eastern Mexico, the first documented case in the order Columbiformes and the first for ants of the genus Pogonomyrmex. Doves visited the periphery of the ants' nest entrance and fed on waste material expelled by ants from inside the nest. Doves also took seeds of the grasses Dactyloctenium aegyptium, Digitaria ciliaris, and the shrub Sida directly from Pogonomyrmex workers. During a 5-day period, we estimated that nearly 20% of the seeds harvested by ants and carried toward the nest were taken by the doves. Inca doves can be defined as facultative kleptoparasites.

Interactions between the American badger (Taxidea taxus) and members of the Canidae have been reported in detail previously in the literature, including the coyote (Canis latrans), swift fox (Vulpes velox), and red fox (Vulpes vulpes). Most of these interactions were cooperative or nonantagonistic; however, a few were exploitative or otherwise antagonistic. Here we report for the first time antagonistic and nonantagonistic interactions between the San Joaquin kit fox (Vulpes macrotis mutica) and the American badger.

The Comal Springs riffle beetle (Heterelmis comalensis) is an endangered species inhabiting springs of the Edwards Aquifer. It is known to exist only in Comal spring in Guadalupe and Comal Counties, Texas, and San Marcos spring in Caldwell and Hays counties, Texas. This species is threatened by decreased water quality and quantity. We tested the association of H. comalensis to spring openings and assessed preference for several habitat variables in an effort to describe the determinants of the narrow range of the species. To test the association of beetles with the spring outlets, we buried meter-long cotton strips over spring habitat as lures and, after 4 wk, collected adults and larvae from the strips. We found beetle abundance was highest within 20 cm of the spring outlet and decreased gradually with distance from the spring source. We tested preferences for the following variables: well water, flow, carbon dioxide (CO₂), temperature, and light, using H. comalensis and Heterelmis vulnerata, a more-widespread species, as a comparison. Both species showed significant preferences for low flow, elevated CO₂, temperatures ~23°C, and darkness. They differed in that H. comalensis preferred well water while H. vulnerata did not. Based on our results, H. comalensis was found primarily in spring source habitat and preferred the water quality conditions found in these habitats.

We document for the first time that Sciurus ignitus, a medium-sized agouti-patterned squirrel with white venter, occurs in Paraguay, being found in the northern Chaco–Pantanal region of the country, where the borders of Paraguay, Bolivia, and Brazil come together. Sciurus urucumus, the only species of squirrel previously known with certainty to range into Paraguay, occurs in the Chiquitano Forest of the northeastern Paraguayan Chaco. We provide details of the Paraguayan habitats for the known specimens of both species. At present, we know of no localities where the two species co-occur. We critically evaluate some of the morphological characters used previously to characterize S. ignitus. Interviews with local hunters, including Aché indigenous ones, coupled with an earlier published account, indicate that the squirrel Sciurus aestuans also occurs in eastern Paraguay's Departamento Alto Paraná, although no specimens are now available from the country.

We investigated the diet of the endemic teiid lizard Aspidoscelis calidipes in the Balsas-Tepalcatepec Basin in the state of Michoacán, Mexico, during 2010 and 2011. We removed, analyzed, and identified stomach contents to order or family. The diet of A. calidipes consisted of 27 prey taxa and the dietary diversity was low (H′ = 0.45). Termites and ants were the most important prey items. Adult and juvenile lizards consumed greater proportions of termites than any other prey item by number, volume, and frequency. Diet diversity of juveniles was higher (H′ = 1.15) than that of adults (H′= 0.28). Dietary overlap between adults and juveniles was 49%.

I observed black-crowned night-herons (Nycticorax nycticorax) swimming and kleptoparasitizing American coots (Fulica americana) at an artificial lake in Pinal County, Arizona. This appears to be the first record of interspecific kleptoparasitism by a swimming ardeid.