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The Davis Mountains cottontail, Sylvilagus robustus, is an endemic species of the Trans-Pecos area of Texas. Although S. robustus previously was believed to be extirpated from the Chisos Mountains, we confirmed existence of a population. We examined intrapopulation and interpopulation variation in S. robustus, as well as the genetic relationship to the eastern cottontail (S. floridanus) using partial sequences of the mitochondrial cytochrome b and control region genes. Six morphometric traits relating to overall size and six cranial characters considered diagnostic for the two subspecies were used to confirm identification of specimens. Our morphological analysis suggested that specimens from the Chisos and Davis Mountains were S. robustus; however, low levels of genetic divergence between S. robustus and S. floridanus appeared inconsistent with species-level recognition for S. robustus.
To assess response of Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis) to postfire conditions, we monitored size of home ranges and core areas and characteristics of vegetation at middens in an area of low-intensity burn. For a larger-scale assessment, we monitored mountain-wide occupancy of middens. Although red squirrels selected unburned locations as sites for middens, mean size of home range in a lightly burned area decreased over time, suggesting high availability of resources in lightly burned areas.
We studied use of habitats and diets of mule deer (Odocoileus hemionus) and feral asses (Equus asinus) by comparing vegetation (i.e., normalized-difference-vegetation index, normalized-difference-vegetation-index rate), elevation, slope, and distances to water-catchments, roads, rivers and canals, and washes used by each species. Distribution was similar with respect to distances to roads, catchments, and rivers and canals in winter, normalized-difference-vegetation index and distance to catchments in spring, distance to rivers and canals in summer, and slope in autumn. Diets (from microhistological analysis of feces) revealed biologically significant overlap during the abundant-forage season (simplified Morisita index >0.60). Diets of mule deer had high proportions of browse (76–85%) in all seasons and low proportions of grasses (1–2%) and forbs (4–8%); whereas, diets of feral asses contained less browse (65–72%) and more grasses (12–16%) and forbs (13–20%).
Information related to home ranges of the nilgai antelope (Boselaphus tragocamelus) was needed to estimate spread of cattle-fever ticks (Riphicephalus microplus and R. annulatus) and to develop management protocols. We captured, placed telemetry collars on, and monitored 10 male and 12 female nilgai antelopes during February 2006–May 2008. We detected no difference between size of home ranges of males and females and determined maximum axes of home ranges of 16.3 and 13.8 km, respectively. The combination of large home ranges and large axes of home range indicates that if cattle-fever ticks are being maintained on nilgai antelopes, then the area in which these antelopes may spread ticks is great.
We used mist nets to survey small migrant and resident birds of scrub habitats in arroyos and adjacent uplands of the northern Chihuahuan Desert during late February–early May 1993–1997. We captured 723 individuals of 49 species. Species diversity was greater in arroyos than in adjacent uplands. Black-throated sparrows (Amphispiza bilineata), white-crowned sparrows (Zonotrichia leucophrys), and green-tailed towhees (Pipilo chlorurus) were captured most frequently. Rates of capture for residents, short-distance migrants, and Neotropical migrants were higher in arroyos than in adjacent shrubland and showed an increase after mid-April caused by an influx of Neotropical migrants heading north to their breeding grounds. Our results suggest that arroyos are important as stopover sites during spring for many migrants, especially Neotropical migrants, as they cross the northern Chihuahuan Desert.
The Texas horned lizard, Phrynosoma cornutum, feeds primarily on harvester ants (Pogonomyrmex) across much of its range. We quantified behavior of P. cornutum foraging on Pogonomyrmex relative to habitat and time. For the duration of their morning activity, 14 lizards were observed; we determined their use of habitat and location of ants that were captured. Lizards spent most of their time under vegetation; the type of vegetation used varied throughout the morning. Most feeding took place in the open and involved ants dispersed away from colonies. When feeding under vegetation, most feeding took place under mesquites (Prosopis), and location of mesquites under which lizards fed was nonrandom with respect to distance from entrances to colonies of ants. Feeding at entrances to colonies was restricted to a shorter period of the morning than feeding on dispersed ants. Males and females differed in use of habitat and in foraging behavior, with males more likely to feed in the open and to feed at entrances of colonies than females.
We assessed four potential sources of error in estimating size of the population of Devils Hole pupfish (Cyprinodon diabolis): net, time of day, diver, and order of diver. Experimental dives (3/day) were conducted during 4 days in July 2009. Effects of the four sources of error on estimates from dive surveys were analyzed using a split-split plot ANOVA. Diver and order of diver had no significant influence on estimates, whereas the effect of presence or absence of a net was significant. Effects of time of day and presence or absence of a net showed a significant interaction with depth of water. Results indicated that pupfish may move upward during the dive, and as a result, the standard methods of dive surveys may underestimate abundance.
Objectives were to determine number and height of sprouts and seedlings following clearcutting of a mesa dominated by pinyon pines (Pinus edulis) and alligator junipers (Juniperus deppeana) in southwestern New Mexico and to determine effects of prescribed burning for control of sprouts and seedlings. No stump of pinyon pine sprouted. Nearly 50% of stumps of alligator junipers sprouted with most occurring in plots with slash removed; the fewest and tallest sprouts occurred in plots with slash uniformly scattered following clearcutting. Nearly 25% of stumps of gray oaks (Quercus grisea) sprouted. Burning in the same year as clearcutting did not affect sprouting of gray oaks as much as other treatments. Not burning clearcuts and leaving slash scattered resulted in the fewest sprouts, and shortest sprouts of gray oaks occurred in plots with slash removed. Seedlings of pinyon pines, alligator junipers, and gray oaks were most prevalent in uncut control plots. Some seedlings of alligator junipers were in plots with slash scattered and removed, and few seedlings were in plots that were burned. Most seedlings of gray oaks were in uncut control plots and plots where slash was removed. Seedlings of pinyon pines grew tallest in plots with slash removed, seedlings of alligator junipers grew tallest in plots where slash was scattered, and seedlings of gray oaks grew tallest in all plots except the uncut control.
We studied bullsnakes (Pituophis catenifer sayi) in the Sandhills of Nebraska. Females matured at ca. 90-cm snout–vent length after two seasons (ca. 33 months old), ovulated in early June, and oviposited in mid-June–early July. Frequently, females did not reproduce each year. The proportion reproducing was a function of size of body and warmth of previous summer. Individual eggs averaged 4% of mass of gravid females and size of egg tended to increase with size of body, but did not vary annually. Based on counts of corpora lutea or oviposited eggs, size of clutch averaged 9.5 and was correlated with size of body. Size of clutch varied among years, even after effects of size of body were removed, and tended to be greater in years with warmer temperatures in April–May. Size of clutches and eggs were correlated inversely. Mass of clutch increased with size of body, averaged 37% of mass of gravid females and 59% of post-gravid mass, and did not vary among years. Bullsnakes appear to be capital breeders with respect to frequency of reproduction, but also may respond to resources during vitellogenesis in spring with changes in size of clutch (income breeding). Mass of eggs and clutches were less plastic. Among Pituophis, size of egg and body decrease with increasing latitude; however, mass of egg standardized to size of body does not vary with latitude. Size of clutch standardized to size of body increases with latitude only in P. melanoleucus. Relative mass of clutch does not vary with size of body within or among populations. Frequency of reproduction and size of clutch exhibit considerable variation, apparently based on effects of climate on acquisition of resources, whereas mass of clutch and size of egg vary less (locally and regionally) and appear to be constrained more by natural selection for optimal dimensions.
A collection of large mammals was recovered from Pleistocene sediments in the Prescott Valley, Yavapai County, Arizona, during an excavation in 1984. We described specimens of Mammuthus cf. columbi, Equus cf. conversidens, Camelops, and Bison from this locality. These are the first reported occurrences of E. conversidens and Camelops in Yavapai County. The mammoth and horse were subadults and the bison and camel were juveniles. Excellent preservation of the mammoth indicated a rapid burial and comparisons to other mammoths suggested the individual was a small male. A radiocarbon date of 13,410 years before present, from fluvio-lacustrine sediments encasing the mammoth, provided a late Pleistocene age for the fauna. The grazing nature of this fauna indicates prevalent grasslands during the end of the Pleistocene in Prescott Valley.
We investigated the importance of size, loss of tail, and running speed of banded geckos (Coleonyx variegatus) in encounters with a predatory snake (Hypsiglena chlorophaea) in experimental arenas. We discovered, contrary to previously reported results and our own hypotheses based on observations in the field, that none of these factors influenced risk of predation, and that autotomy was not used commonly as a tactic to escape predators. Based on these results and observed behavior during predation trials, we question whether tail autotomy in this species is an effective anti-predator adaptation.
Selection of forage by wildlife may drive habitat selection and influence rates of survival and reproduction. To understand patterns in use of forage by elk (Cervus elaphus) in a tallgrass prairie, we collected groups of fecal pellets during 2005–2007 and determined patterns of use based on stable-isotope ratios of carbon and microhistological analysis. Elk consumed the greatest diversity of forbs during summer and the greatest diversity of grasses during winter. While our study site was dominated by warm-season C4-grasses, stable-isotope analysis indicated that elk consumed primarily C3-vegetation (cool-season grasses, forbs, or browse) during summer and winter.
We measured ingestion by Attwater's pocket gopher (Geomys attwateri) in the coastal prairie of Texas by placing feeding chambers in their tunnels. We constructed a nutrient budget from ingestion, species of plants eaten, and nutrient content of these plants, and we compared it to that for the hispid cotton rat (Sigmodon hispidus), also common in this habitat, and the laboratory rat. Concentration of minerals ingested by G. attwateri appeared sufficient for growth and reproduction. Concentration of protein was lower and concentration of fiber was higher in diets of G. attwateri than in diets of S. hispidus or that was required for laboratory rats. High concentration of fiber reduces digestibility and impedes assimilation of protein. We concluded that protein was likely a limiting nutrient and that a low protein:fiber ratio in the diet during summer could be responsible for the observed decline in reproduction in that season.
Aboveground mounds and underground burrows are multifunctional and influence behavior and habitat of Gunnison's prairie dogs (Cynomys gunnisoni). Four colonies were studied June–September 2004 to examine function of mounds with respect to vigilance for predators, and to estimate magnitude of soil mixed by these prairie dogs. Frequency of vigilance atop mounds increased in taller vegetation and individuals at perimeters of colonies oriented toward the outside more frequently than to the interior of colonies. Mounds accounted for an average of 10,374 kg of soil/ha that was excavated from the burrow. This mass of subsoil moved to the surface and the 7–17 m3 of air in the burrow make the geomorphic effect of prairie dogs potentially significant.
The big red bat, Lasiurus egregius, was known from only four localities in Panama, French Guiana, and Brazil. I report a fifth locality from eastern Honduras, extending the known range >1,200 km to the northwest, well into Central America. On 9 May 1998, I captured one male and one female in a mist net near Guayabo de Catacamas, Olancho, Honduras. Both specimens were caught over water. The female was lactating and the male was reproductively inactive. This brings the total number of specimens of L. egregius to six worldwide.
In total, 14 new records of birds are reported from coniferous forests and other habitats in the municipality of Nanacamilpa, Tlaxcala, Mexico. These additional records reinforce the supposition that the region is important with respect to conservation of avian diversity in Mexico.
We initially observed native stem-boring beetles (Amphicerus bicaudatus) feeding on stems of invasive tamarisks (Tamarix) at Bonny State Park, Yuma County, in eastern Colorado. At 11 sites in Colorado, Nebraska, and Kansas, we examined tamarisks and the most common co-occurring native tree, eastern cottonwoods (Populus deltoides), for the occurrence of this beetle. We detected evidence of feeding and development of insects at nine of the sites and in 112 of 579 tamarisks. Among sites, A. bicaudatus occurred in nearly 20% of tamarisks. Only 13 of 480 eastern cottonwoods showed signs of activity by A. bicaudatus. During dissections of stems of tamarisks, nearly 90% of adult beetles were in live versus dead stems.
Three new records of late Pleistocene fossil peccaries come from localities in western Oklahoma and improve on the only previous record from the state. Isolated occurrences of partial jaws at Rush Creek, Grady County, and south of Yukon, Canadian County, represent the flat-headed peccary, Platygonus compressus. An assemblage with three taxa of mammals from a canal near the Quartz Mountains, Jackson County, includes a prairie dog Cynomys, a mammoth Mammuthus, and an unidentified peccary, Tayassuidae indeterminate. The last of these specimens includes a well-preserved skeleton of a foot, partial upper tusk, and occipital condyle.
We report the first record of the jaguarundi (Puma yagouaroundi) in the state of Guanajuato, Mexico. This record expands the distribution of this species by 117 km to the west into the Mexican Central Plateau and increases the number of species of felids reported in Guanajuato to five.
Fragmentation of habitats and distance between drainages in the semi-arid Lower Colorado River Basin has contributed to development of disjunct populations of caddisflies in the region. Caddisflies in streams cluster into discrete regional assemblages in the basin with significantly different assemblages. Distances between drainages in Arizona will likely increase genetic drift in disjunct populations of caddisflies and further reduce genetic variability, which may be important in conservation.
The wetland plant Ludwigia peploides (floating primrose-willow) often is problematic in the southern USA, as well as elsewhere in its introduced range. Surveys to identify potential herbivorous insects to use as biological controls have focused on South America, but implementing a management program with foreign insects in the USA is difficult and can take years of testing in quarantine. During 2006–2008, populations of floating primrose-willow were surveyed in the southern USA to determine presence and extent of native herbivorous insects. At least nine species were identified, represented mainly by weevils (Curculionidae) and leaf beetles (Chrysomelidae). Of these, two were undescribed species of weevils (Auleutes), and six species, including Tyloderma sphaerocarpae and Chaetocnema, have never been associated with floating primrose-willow.