Populations of lesser prairie-chickens (Tympanuchus pallidicinctus) have declined sharply across the range of the species, including southeastern New Mexico. Several possible causes for this decline have been suggested, including overgrazing by livestock. To test this hypothesis, vegetative composition of active and abandoned leks of lesser prairie-chickens and the pastures in which they were located was measured using the line-point sampling method. Vegetative composition of active leks and the pastures in which they were located was significantly different from those of abandoned leks and surrounding pastures in all 3 years of the study. Active leks and surrounding pastures had significantly more bluestem (Andropogon) and less dropseed (Sporobolus) than did abandoned leks and surrounding pastures. Abandoned leks were closer to honey mesquites (Prosopis glandulosa) >60 cm in height than were active leks. Results are symptomatic of overgrazing, which is detrimental to populations of lesser prairie-chickens.

We modeled how variation in size of home ranges and annual movements of white-tailed deer (Odocoileus virginianus) in southern Texas altered ability to manage deer within various sizes of management units and discussed implications for spread of disease. The percentage of adult (≥3.5 years) males remaining on management units varied <4% across three sites in southern Texas. The spatial extent of spread of disease by adult males would be less than movements associated with migration or dispersal. Based on size of home ranges and movements, >98% of males would use management units of 1,000 km² because their use of space would not result in use of adjoining management units. Migration of deer in northern latitudes resulted in 20% of the population using management units of 1,000 km², which potentially could expose large areas (>25,000 km²) to disease because a greater percentage of deer would use adjoining management units compared to deer in southern latitudes. Our results are useful in determining size and configuration of management units, which will improve formulation of management plans, analysis of data from harvests, and prediction and control of disease.

This research compared surveys of vegetation that were conducted in Big Bend National Park, Brewster County, Texas, during 1955–1960 and 1968–1969 with data collected in 2005 and 2006. Comparisons were based on percentages of cover and flora at five study sites. Results suggest some increases and decreases in certain types of vegetative cover since creation of the park, although no trend was consistent across elevations and years. Sites at lowest and highest elevations had significant increases in shrubs. Except for one, all sites had significant differences in total cover. Some species had changed in overall abundance. Lehmann lovegrass (Eragrostis lehmanniana) was becoming a dominant grass in foothills of the Chisos Mountains and surrounding Chihuahuan Desert. In contrast, leatherstem (Jatropha dioica), fragrant sumac (Rhus trilobata), tarbush (Flourensia cernua), four-wing saltbush (Atriplex canescens), desert hackberry (Celtis pallida), and Mexican mock vervain (Glandularia bipinnatifida) had disappeared from some, or all, locations where they were recorded previously.

To examine pathways, timing, and destinations during migration in spring, we attached satellite-monitored transmitters (platform transmitting terminals) to 10 northern pintails (Anas acuta) during February 2001, at Point Mugu, Ventura County, California. This is a wintering area on the southern coast of California. We obtained locations from five adult males and three adult females every 3rd day through August. Average date of departure from the wintering area was 15 March (SE  =  3 days). We documented extended stopovers of ≥30 days for several northern pintails that could have accommodated nesting attempts (San Joaquin Valley, southwestern Montana, southern Alberta, north-central Nevada) or post-nesting molt (eastern Oregon, south-central Saskatchewan, northern Alaska, central Alberta). Wintering northern pintails from the southern coast of California used a wide range of routes, nesting areas, and schedules during migration in spring, which was consistent with the larger, wintering population in the Central Valley of California. Therefore, conservation of habitat that is targeted at stopover, nesting, and molting areas will benefit survival and management of both wintering populations.

Studies quantifying the grouping and forage-selection patterns of scimitar-horned oryx (Oryx dammah) in Texas or in their native range, where they are probably extinct, are scarce. This oryx is less dimorphic in size than most ruminants; dimorphism in size is associated with intersexual differences in grouping patterns and diet. We hypothesized that males and females associate in mixed-sex groups and do not exhibit intersexual differences in selection of forage. Our study was conducted at Mason Mountain Wildlife Management Area, Mason County, Texas, during June 2006–April 2007. Grouping patterns were measured from systematic surveys conducted from vehicles at dawn and in the afternoon in 6 different months. We collected fecal samples from individuals of known sex and assessed diet using fragments of plants in fecal samples. We measured seasonal availability of food in areas where fecal samples were collected. We encountered mixed-sex groups more often than same-sex groups and we detected no difference between sexes in diet. However, there were differences among seasons in selection of forage. The majority of diet was grasses, such as Sporobolus and Eragrostis, and forbs. Our study supported expectations based on similar-sized males and females.

Reliable estimates of size of populations are critical for successful management of translocated desert bighorn sheep (Ovis canadensis mexicana). As costs decrease and quality improves, remote cameras are increasingly used as a non-invasive tool to monitor populations of wildlife, but their efficacy has yet to be evaluated in a diversity of species and habitats. Here we investigate whether remote cameras, in combination with a simple mark-resight model, produce estimates of size of populations of desert bighorn sheep comparable to those derived from surveys conducted on the ground and using helicopters in the Fra Cristobal Range of south-central New Mexico. We determined that estimates of size of populations derived from remote cameras were comparable to those produced from direct observations obtained by surveys from helicopters and on the ground, that ca. 25 sequential samples of photographs produced comparable estimates of size of populations, but that photographs of single desert bighorn sheep dramatically lowered estimates of size of populations, and that placement of remote cameras on wildlife guzzlers in July produced the greatest number of photographs in the shortest time. Our results suggest that use of remote cameras may be an accurate, low-cost, and non-invasive means of estimating size of populations of desert bighorn sheep in New Mexico. Further research is warranted, ideally in tandem with ongoing surveys on the ground and using helicopters, in other management areas.

The zooplankton fauna of freshwater systems of the Chihuahuan Desert was surveyed 2005–2008. Samples were obtained from habitats including natural lakes, ephemeral waters, springs, and reservoirs. Copepods were sorted and identified to species. Including previous surveys, a total of 38 species occur in the Chihuahuan Desert, the checklist includes 6 calanoids (1 Temoridae, 5 Diaptomidae), 24 cyclopoids (12 Eucyclopinae, 12 Cyclopinae), and 8 harpacticoids. These species were assigned to different biogeographic categories (i.e., cosmopolitan, Nearctic, Neotropical, potential endemics). Results indicated that the Chihuahuan Desert, a transitional biogeographic region in Mexico with both Nearctic and Neotropical influences, represents an interesting geographic and environmental realm characterized by a balanced mixture of elements from different origins and affinities. There is a relatively high proportion (23%) of species that probably are endemic.

The harvester ants Pogonomyrmex barbatus and P. rugosus serve as hosts for the parasitic ants P. anergismus and P. colei. Recent molecular studies demonstrated that morphology is unreliable for identification of hosts because the hosts contain cryptic species. Using mitochondrial-DNA sequences, we determined identity of 15 of 16 known populations of hosts, and in 9 instances, the identity of the particular host colony. Hosts are composed of 6 reproductively isolated lineages. While P. colei is known only from a single host, P. anergismus occurs in five distinct hosts and appears to have a much broader geographic range. We report seven new locality records for P. anergismus. Range extensions for P. anergismus in the United States consist of southwestern Texas including Big Bend National Park, northwestern Texas, central New Mexico, and south-central Arizona. We discuss factors that may influence dispersal of parasitic ants and host-parasite co-evolution.

During 2002–2003, we collected samples of leaf litter (10-cm diameter) from two woodland sites in southwestern Louisiana and one in central Florida. In Louisiana, we collected at four times (autumn, winter, spring, and summer) and in Florida in spring and summer. We divided each sample into two layers, an upper leafy layer (1–2 cm in depth) and a lower layer of humus (1–2 cm in depth). We detected six species of tardigrades in samples from Louisiana and five in samples from Florida. Seasonal variation in density of tardigrades was pronounced at each site. Tardigrades generally were more abundant in the upper layer. Density and diversity of tardigrades in the leaf litter at these sites were less than in mountainous areas of Italy and Tennessee, USA.

For captive-bred Devils River minnows (Dionda diaboli), which are federally listed as threatened, we measured critical thermal maxima when they were acclimated at 18, 22, 24, and 27°C. Critical thermal maxima were 32.6, 34.3, 35.3, and 37.8°C and were positively correlated with temperatures of acclimation, but not with either gender or size. There was high pre-test mortality (39%) for fish held at 28°C for 72 days.

Effects of in-stream hiking on benthic standing stocks and drifting aquatic invertebrates and on organic matter were examined in the North Fork of the Virgin River, Zion National Park, Washington County, Utah. Densities of drifting aquatic invertebrates and organic matter increased with increasing numbers of hikers and reached a threshold level at high numbers of hikers. However, there was no apparent longer-term effect on standing stocks of benthic invertebrates or on organic matter. Densities of benthic invertebrates and organic matter did not differ among sites. Results suggest that in-stream hiking in the North Fork of the Virgin River increases drifting by invertebrates, but invertebrates from nearby undisturbed patches readily colonize impacted reaches.

We report two fossil specimens of the desert tortoise (Gopherus agassizii) from Cathedral Cave, White Pine County, Nevada. These specimens are diagnosed as G. agassizii based on morphology of the scute sulcus on the entoplastron and anterior constriction and morphology of the scute sulcus of the epiplastron. The fossils have a maximum age of 146,020 ± 2,584–151,200 ± 4,400 years, and represent the first record of Pleistocene turtles from within the hydrographic Great Basin. Documentation of fossil turtles within the east-central Great Basin at this time interval suggests that turtles were extirpated from much of the Great Basin by environmental changes or other factors that took place sometime between deposition of the Cathedral Cave deposit and the latest Pleistocene, when diverse reptilian assemblages across the Great Basin were devoid of turtles.

Wild boars (Sus scrofa) are increasing in abundance and geographic distribution throughout North America. Our objectives were to determine daily and hourly activity patterns. We placed global-positioning-system collars on 25 wild boars from two sites in southern Texas. Wild boars at both sites displayed highly nocturnal activity patterns, and during the dormant and early growing season, activity increased with rising temperatures.

The ocelot, Leopardus pardalis, is a medium-sized Neotropical felid with a relatively wide geographical distribution. Across their range, ocelots exhibit clinal variation in pattern and color of pelage. Despite this variation, few aberrant genetic morphs have been documented. This record describes the first apparent leucistic variant for the ocelot: a white female with black markings that was treed on three occasions over a 3-year period in the transitional Chaco of western Paraguay.

We present new information on 26 species of birds encountered in the Plains of Tehuantepec, Oaxaca, Mexico, including four species new to the state: snow goose (Chen caerulescens), prairie falcon (Falco mexicanus), red-throated pipit (Anthus cervinus), and bobolink (Dolichonyx orizyvorus). Improving knowledge of status and distribution of species in this area is important to assess conservation risk due to proposed establishment of thousands of wind turbines on the Pacific lowlands of the Isthmus of Tehuantepec.

Cyprinids belonging to the genus Dionda have a relatively broad distribution in southwestern North America. However, validity of populations in several of the nominal species has not been examined rigorously. During the course of a conservation-genetics study of Dionda in western Texas we determined that one population presumed to represent Dionda episcopa instead belongs to Dionda argentosa. This extends the native range of D. argentosa to include the lower Pecos River basin in addition to its currently recognized distribution in three tributaries of the Rio Grande. Conservation implications for both species are discussed.

Ecological boundaries have been of interest to naturalists since the time of Darwin and Wallace because they are transitional zones on the landscape across which distinct changes occur in constitution of plant and animal communities. In the xeric landscapes of the central Baja California Peninsula, fan palm (Erythea armata and Washingtonia robusta) oases are small (usually <1 ha) mesophilic islands of structurally complex habitats. We report new records of mesophilic reptiles and amphibians from the adjacent Californian biome in palm groves of the Sonoran region; these highly philopatric species provide evidence of earlier cooler and moister Pleistocene environments. The fan palm oases of the central Baja California Peninsula are natural laboratories for the study of evolutionary processes because they provide unique mesic habitats in a changing desert landscape.

We report the first record of Van Gelder's bat (Bauerus dubiaquercus) from El Salvador, Central America. This is the first report of Van Gelder's bat from the Pacific versant of Mesoamerica, between Guerrero, Mexico, and Costa Rica, a distance of ca. 1,850 km.

Ten new county records and significant extensions of known geographic ranges are reported for 10 taxa of fishes within 6 families (Atherinopsidae, Catostomidae, Centrarchidae, Cyprinidae, Fundulidae, and Percidae) from five rivers in Arkansas. Records are presented for the shoal chub (Macrhybopsis hyostoma), highfin carpsucker (Carpiodes velifer), golden redhorse (Moxostoma erythrurum), pealip redhorse (Moxostoma pisolabrum), northern starhead topminnow (Fundulus dispar), Mississippi silverside (Menidia audens), dollar sunfish (Lepomis marginatus), crystal darter (Crystallaria asprella), mud darter (Etheostoma asprigene), and river darter (Percina shumardi).

We describe a method for making clay mimics of bird eggs. These eggs can be used in experiments that require many uniform, accurate artificial eggs. We developed methods and made about 1,000 clay eggs at a cost of $0.55 each.

This is the first report of cannibalism in a free-ranging population of jaguars (Panthera onca). An encounter among unfamiliar jaguars may have provoked social stress, a behavior reported in other free-ranging carnivores.

We collected 12 mountain clingfish Gobiesox fluviatilis in the Río Tamazula that represent the first record of the species in both the Río Culiacán basin and the state of Sinaloa, Mexico. We compared proportions of body and counts of fin rays of the new specimens with those previously reported for this species.