We compared small mammals in Gulf cordgrass (Spartina spartinae) to coastal-prairie and low-marsh, Spartina alterniflora communities, and we considered the effect of standing-crop biomass and nutrient concentration in plants in the Gulf cordgrass community on dynamics of populations of small mammals. We predicted lower species richness and density of small mammals and shorter residence time in Gulf cordgrass because of little vertical habitat structure, sparse ground cover, and low abundance of dicots, plants that contain nutrients necessary for reproduction by hispid cotton rats (Sigmodon hispidus). Richness in Gulf cordgrass (seven species of rodents) was similar to coastal prairie (six species plus three non-native rodents) with S. hispidus and fulvous harvest mice (Reithrodontomys fulvescens) numerically dominant in both communities. Density of S. hispidus was higher in Gulf cordgrass likely reflecting high standing-crop biomass; however, lack of ground cover contributed to low residence time. Low residency and increase in density during months of increase in density in coastal prairie indicated that Gulf cordgrass functioned as a dispersal sink from adjacent coastal prairie. Density and residency of R. fulvescens were lower in Gulf cordgrass likely reflecting lower quality of habitat because of lack of vertical structure. Low biomass of dicots in Gulf cordgrass would seem to limit availability of nutrients, but nutrients in green stems of S. spartinae were sufficient for growth and reproduction for S. hispidus.

Indirect estimates of rates of survival for juvenile songbirds typically are used in population modeling. However, survival in the initial post-fledging period can vary widely among species and indirect estimates may yield misleading information regarding populations. This is especially important when considering species that are experiencing population declines, like the western bluebird (Sialia mexicana). I calculated estimates of survival of western bluebirds during the post-fledging dependent (1–7 days after fledge) and semi-dependent (8–20 days after fledge) periods using radiotelemetry on 27 fledglings in a restoration-treated forest of ponderosa pine (Pinus ponderosa) in northern Arizona. Daily rates of survival were 0.96 (dependent)–0.99 (semi-dependent) in the post-fledging period and yielded an overall rate of survival of 0.64. Predation was the primary cause of mortality. Fledglings moved ca. 100 m from the nest during the dependent period and averaged 200–300 m from the nest in the semi-dependent period. Movements were highly variable in the semi-dependent period. My results provide the first estimate of survival for fledgling western bluebirds. Because my estimates were relatively high compared to other species of songbirds, and patterns of movement suggested that adequate foraging resources were available, my estimates should be treated as rates of survival for bluebirds in good habitat when considering populations from a variety of habitats.

Sympatry can create special dynamics between populations and impact management strategies for each species. We estimated size and overlap of home ranges and core areas of sympatric female mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) in west-central Texas. We captured 50 mule deer and 53 white-tailed deer, fitted them with radiocollars, and monitored them during 2000–2002. Average (±SE) size of home range of mule deer in spring was 3.9 ± 0.32 km², while that of white-tailed deer was 4.32 ± 0.77 km²; sizes of home ranges in summer were 2.82 ± 0.32 and 2.08 ± 0.23 km², respectively. Interspecific overlap of home range between seasons was similar to intraspecific overlap. Overlap in core area also was similar within and between species during summer, but interspecific overlap in core area was less during spring.

Mule deer (Odocoileus hemionus) have been declining throughout the western United States and white-tailed deer (O. virginianus) have remained stable or increased. In areas of sympatry, it is important to understand dynamics between the two species. Crockett County, Texas, provided an area where the two species occurred sympatrically at relatively high densities. In summers 2004–2005, we captured adult deer and fitted them with radiocollars and vaginal-implant transmitters. We monitored vaginal-implant transmitters to record date of parturition, to locate birth sites, and to aid in capture of neonates. We captured 101 neonates (68 mule deer and 33 white-tailed deer). We observed 45 parturition sites and 249 day-time bedding sites of fawns. Parturition in mule deer began ca. 1 month after white-tailed deer. Birth sites of mule deer were at higher elevations and on steeper slopes than those of white-tailed deer. Mule deer gave birth under junipers (Juniperus) more often than did white-tailed deer. Our best model used elevation, height of horizontal hiding cover, type of vegetation, canopy shrub, and an interaction between vegetation type and canopy shrub to differentiate between bedding sites of fawns of mule deer and white-tailed deer. Fawns of mule deer bedded at higher elevations in shorter hiding cover and commonly under junipers, whereas fawns of white-tailed deer commonly bedded under honey mesquite (Prosopis glandulosa) or in herbaceous vegetation. Our data show that fawns partition habitat in a manner similar to adults in this area.

We investigated the impact of disturbance by humans on distribution of small mammals at the northeastern edge of the Chihuahuan Desert. We determined composition of small-mammal communities and characteristics of soil at water tanks, roadsides, and open range. Nitrogen and moisture in soil did not vary across sites, but compaction of soil, vegetational cover, and composition of small-mammal communities did vary. Small mammals were distributed as expected with the exception of four omnivores (Mus musculus, Neotoma micropus, Peromyscus leucopus, and P. maniculatus), which were at higher density on sites with high disturbance by humans and relatively low vegetational cover. Activity of humans may impact some small mammals by drawing them to areas that contain high levels of human-generated resources.

Point-quarter, random-pairs, 0.004-ha-arm-length-rectangle, and 0.04-ha-circle methods for sampling density, diameters, and size categories were used in an oak-hickory (Quercus-Carya) woodlot. Results from three trials for each method were compared to actual density of trees determined from a total count of trees in the woodlot. With respect to accuracy per time spent, the 0.04-ha circle was the best method and the point-quarter method was the worst. These findings improve on previous studies because, for the first time, repeated trials in the field were employed.

We compiled 355 observations of foraging events of peregrine falcons (Falco peregrinus) in Grand Canyon, downstream from Glen Canyon Dam on the Colorado River during 1973–1995, and documented abundance of prey, foraging behavior, and success in foraging. Peregrine falcons attempted to forage on ≥44 species, including ≥40 species of birds: swifts and swallows (29%), waterfowl (Anseriformes, Podicipediformes, and similar birds, 27%), other waterbirds (waders and other large, non-anseriform waterbirds, 11%), bats (10%), large wasps (8%), and other species (15%). Frequency of foraging during the breeding season was positively related to overall abundance of prey, but relative intensity of predation (ratio of relative frequency of attack on a species to mean abundance of that species) increased on most species of prey in the usually turbid lower reach, where prey were less abundant. Air-to-air strikes were most common (94% of 271 cases for which data were available), followed by air-to-water strikes (4%), and air-to-ground strikes (2%). Tandem attacks occurred in ≥43% of cases. Overall foraging success was ≥52%, and was highest on large wasps (100%) and bats (87%), intermediate on large waterbirds (63%), swifts, swallows, and small terrestrial birds (42%), and waterfowl (40%), and lowest on belted kingfishers (Ceryle alcyon; 18%) and small shorebirds (<3%). Foraging success was related to abundance of prey and number of co-foraging falcons, and was negatively related to relative body mass of prey. Most dietary biomass was derived from waterfowl (64%) and large waterbirds (25%), whereas swallows and swifts contributed only 3%. The low and variably turbid segment near the dam had greater abundance of prey and lower relative intensity of predation compared to the usually turbid segment downstream, but distribution and overall frequency and success of foraging by peregrine falcons were not affected by regulation of flow.

Small mammals and ground-dwelling invertebrates were sampled seasonally on active colonies of black-tailed prairie dogs (Cynomys ludovicianus), Phostoxin®-treated colonies, and non-colonized short-grass prairie to assess potential impacts of Phostoxin® on non-target species in the Texas Panhandle. Eleven species of small mammals were captured. Northern grasshopper mice (Onychomys leucogaster) were more abundant on active prairie dog colonies, whereas abundances of North American deermice (Peromyscus maniculatus) and plains harvest mice (Reithrodontomys montanus) did not differ among treatments. Total abundance of small mammals and relative abundances of other species did not differ among active colonies, Phostoxin®-treated colonies, and non-colonized sites. Ground-dwelling invertebrates were more abundant on active colonies than on Phostoxin®-treated colonies or non-colonized sites. Results of this study indicate that short-term impacts of control of prairie dogs with Phostoxin® on non-target small mammals and ground-dwelling invertebrates is limited, but may be significant for individual species. Additionally, in short-grass prairie ecosystems, vegetative alterations made by prairie dogs may not influence populations of small mammals as much as in tall or mixed-grass prairies. However, active colonies were used more by northern grasshopper mice and ground-dwelling invertebrates, indicating that this habitat is important for these species.

Understanding what drives population dynamics is a key tool for conserving species in fragmented habitats. We evaluate hypotheses explaining fluctuations in populations of flat-tailed horned lizards, Phrynosoma mcallii, in the Coachella Valley, California. This species has the smallest range of any horned lizard in the United States. Within portions of its range, there are potentially conflicting activities, such as suburban development, agriculture, off-road recreation, and activities along the international border. We analyzed fluctuations in populations with respect to resource variables during 2001–2007. Unlike results for other desert lizards, population dynamics of horned lizards did not correlate positively with rainfall. Compaction of sand, abundance of harvester ants, annual rainfall, and annual cover of plants all contributed to parsimonious models, but contributions of these variables varied between year and criteria for the dependent variable (occurrence of horned lizard). We also examined demographic characteristics of increasing and decreasing populations. Rates of growth of hatchlings and age at sexual maturity provided a mechanistic explanation for the observed population dynamics, and were consistent with a food-limiting hypothesis.

The segment of the Rio Grande between International Falcon Reservoir and Del Rio, Texas (distance ca. 350 km), remains largely unexplored ornithologically. We surveyed nocturnal birds monthly during February–June 1998 at 19 stations along the Rio Grande (n  =  6) and at upland stock ponds (n  =  13) in Webb County, Texas. We conducted 10-min point counts (n  =  89) after sunset and before moonset. Four species of owls and five species of nightjars were detected. Nightjars, as a group, were nearly five times more abundant (mean number/count  =  2.63) than owls (mean number  =  0.55). The most common owl, the great horned owl (Bubo virginianus), had a mean number of 0.25/point count. The mean for elf owls (Micrathene whitneyi) was 0.16/point count. The most common nightjars were the common poorwill (Phalaenoptilus nuttallii; 1.21/point count) and lesser nighthawk (Chordeiles acutipennis; 1.16/point count). Survey sites on the river supported more species (mean  =  2.2) than did upland stock ponds (mean  =  1.4). However, only one species (common pauraque, Nyctidromus albicollis) showed a preference for the river sites. Our results establish this segment of the Rio Grande in southern Texas as an area of high diversity of nightjars in the United States, matched (in numbers of species) only by southeastern Arizona and southwestern New Mexico.

California towhees (Pipilo crissalis) defend all-purpose, type-A territories throughout the year and are believed to remain on home ranges for successive breeding seasons. I present the first data regarding use of space by California towhees from a long-term study of a color-banded population. I examined individual site-fidelity to home ranges over 5 breeding seasons and combined this information with radiotelemetry data to assess sizes of home ranges and use of habitats. California towhees exhibited strong site-fidelity to breeding territories. All (n  =  31) individuals located >10 times in a season were site-faithful across years for up to 4 years. Average size of home range was 0.83 ± 0.31 ha. Size of home range did not differ by sex, and paired birds occupied similar home ranges. All home ranges were composed of a variety of habitats, including open field, dense forest, and riparian areas. California towhees used habitat types differentially throughout the breeding season, and nested in a variety of plants. Prior to and following nesting, they were most often in open areas that provided good forage. While nesting, males and females were most often in dense vegetation. Because they defend type-A territories year-round, potentially for their entire lives, California towhees may benefit from settling on home ranges with high diversity of habitats that can meet fluctuating needs for resources.

We studied the spider fauna of Ash Meadows National Wildlife Refuge on six collecting expeditions during October 2004–August 2005. Spiders collected during these field trips produced ≥81 species in 60 genera and 26 families. Faunal diversity was dominated by Salticidae (≥13 species in seven genera), followed by Lycosidae (eight species in seven genera), Araneidae (eight species in seven genera), Gnaphosidae (seven species in seven genera), and Philodromidae (four species in four genera), with Thomisidae, Linyphiidae, Dictynidae, Theridiidae, Miturgidae, Pholcidae, and Tetragnathidae represented by two to seven species in one to three genera each. A total of 14 other families was represented by single species in single genera. The family Lycosidae was at more sites than any other family and it was the family with the largest number of individuals collected. We report an overall landscape-based density of species of only 0.96 species/km² and, although 45.7% of species were represented by single specimens, we conclude that the fauna is depauperate. This is consistent with other low-elevation desert and playa-dominated habitats in North America, and might be attributable to limited formation of soil.

Reproductively mature male Dionda diaboli, the Devils River minnow, exhibited agonistic and courtship behavior in presence of conspecifics under laboratory conditions. Dionda diaboli spawned over small trays of gravel and did not use a cavity or a crevice. Devils River minnows were non-communal, territorial, broadcast spawners and agonistic behavior consisted of chases, parallel swims, lateral displays, circle swims, and head butts. Courtship behavior consisted of a male approaching a female and pushing her down toward the substrate (male-female approach) prior to spawning. Spawning did not occur until a male had established dominance in the hierarchy.

We report on two specimens of Rhadinaea myersi from Mexico. One of these represents a new record for the state of Guerrero, and both extend the known distribution and confirm the presence of the species in southern Oaxaca, where it has not been collected since the 1970s.

Box turtles are opportunistic omnivores, and consume a wide variety of fruits. Therefore they might play an important role in dispersal of seeds of a variety of plants. We described the diversity of seeds recovered from feces of Terrapene carolina and T. ornata and made comparisons between them. There was a moderate level of dietary overlap based upon diversity of seeds in the feces. Terrapene carolina had a significantly higher species richness of seeds in its feces than T. ornata. Additionally, we documented seeds of four plants (Celtis, Passiflora, Phytolacca americana, and Platanus occidentalis) that previously were not known to be consumed or dispersed by box turtles.

Male and female specimens of a chordeumatid milliped, Branneria bonoculus, were collected in March 2003 from leaf litter in deciduous and pine forest from Lake O' the Pines, Marion Co., Texas. The species was described originally from an unknown site in Nevada County, Arkansas, which is ca. 145 km northeast of the new locale. As such, this represents only the second time B. bonoculus has been reported in the literature, and more importantly, we document the discovery of a family of millipeds that is new for Texas.

Nest predation involving a California kingsnake (Lampropeltis getula californiae) and two fledglings of least Bell's vireo (Vireo bellii pusillus) was observed along the San Luis Rey River in northern San Diego County, California. The kingsnake was discovered consuming a fledgling when the adults were observed mobbing the snake. The kingsnake then proceeded to systematically search for the second fledgling by traveling out and back from the nest multiple times over the next 15 min, each time in a new direction, traveling ca. ≤6–10 m before returning to the nest. The snake then found the original roosting branch of the surviving fledgling and proceeded quickly toward the fledgling that had moved ca. 15 m away. The kingsnake traveled this distance in ca. 2 min and killed and consumed the last fledgling. While California kingsnakes have been reported to feed on birds and bird eggs, this systematic searching behavior has not been described previously.

On 10 August 2005, a Mount Lyell shrew (Sorex lyelli) was collected at 3,630 m elevation in Humphreys Basin, John Muir Wilderness Area, Fresno County, California. This specimen extends the known range of S. lyelli to the south by 55 km, increases its upper elevational range by ca. 500 m, and is the first alpine record. Prior to our finding, S. lyelli had been collected only in Mariposa, Mono, and Tuolomne counties, at elevations of 2,100–3,156 m, typically in sub-alpine herbaceous vegetation along fast-running streams associated with riparian shrubs, and less frequently in thickets of sub-alpine sagebrush. This record is from an alpine lakeshore well above treeline, with vegetation limited to sedges, grasses, and forbs. This specimen represents the highest elevational record for Sorex in the Sierra Nevada of California.

An updated distribution for the endemic, predaceous diving beetle, Heterosternuta sulphuria, consists of four new locations in the Ozark and Boston Mountain ecoregions of Arkansas. To date, a total of 32 specimens have been collected from these locations that are primarily spring-water influenced, small, shaded aquatic systems. Two populations are recorded for currently protected areas; Hobbs State Park-Conservation Area and Sherfield Cave (effluent stream). The addition of H. sulphuria to the biota list from Sherfield Cave further highlights conservation efforts focused on this unique cave and stream system. The habitat from which H. sulphuria has been collected includes stream margins within sediment-free gravel and cobble substrate, under leaf material covering bedrock, and within small, shallow depressions and crevices in bedrock. From current surveys, sulphuria has been the brightly colored member of the Hydroporinae collected from these permanent aguatic habitats and co-occurs only with the genera Sanfilippodytes and Hydrocolus.

On 27 October 2004, in Sierra de las Minas Biosphere Reserve, Guatemala, we observed a strong-billed woodcreeper (Xiphocolaptes promeropirhynchus) chase and attempt to capture a mouse. The mouse jumped out of a bromeliad the woodcreeper was probing seconds earlier. If the woodcreeper was attempting to capture the mouse to eat it then it might have been opportunistically using a locally abundant food source although consumption of mammalian prey by woodcreepers has not been documented.

Described husbandry practices for pocket gophers are rare. Antiquated practices do not satisfy current husbandry standards, requiring investigators to modify methods to meet the needs of their research. We report techniques for housing Baird's pocket gopher (Geomys breviceps) that sustain health of captives, encourages natural behaviors, and meet necessary husbandry requirements. Twenty-six G. breviceps were housed at the University of Arkansas at Little Rock over an 18-month period. A diet consisting of fresh vegetation promoted apparently normal development, and parasitic treatments were effective. Individuals were housed within simulated tunnel systems constructed of multiple cages and plastic tubing and allowed to structure their environment with a combination of topsoil, Bermuda hay, and pine wood chips. Animals readily adapted to this caging system, which can be easily disassembled and sanitized for routine maintenance. Given the effectiveness of these techniques at sustaining G. breviceps, they may be applicable to other species of pocket gophers.

We report on a late-summer, above-ground aggregation of foothill yellow-legged frogs (Rana boylii) in the Diablo Range, Santa Clara County, California. Our observation provides the first published account of aggregation in this species.