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We documented habitat associations of elk (Cervus elaphus) in spring, summer, and autumn, and identified features of habitats that were most closely related to nutritional condition. We tracked 23–56 radiocollared females, modeled nutritional condition as a function of vegetative relationships, and identified variables influencing distribution using presence modeling. Home ranges included quaking aspens and large tracts of wildfire-burned vegetative cover in excess of their availability in the landscape, and elk were located in aspen and burns far in excess of their availability. Accrual of body fat was most closely and negatively associated with abundance of pinyon-junipers, ponderosa pines, and other coniferous vegetation. Models revealed strong associations with areas at higher elevations and <5 km from water, which are associated with open water and increased vegetation. Distribution, quality of habitat, and nutritional condition of elk can be affected by management aimed at opening coniferous vegetation, increasing abundance and distribution of aspens, and promoting natural or prescribed burning. These actions would be most effective ≤5 km from water.
On the Llano Estacado of Texas, roads and agricultural development have divided once continuous prairie into a patchwork of habitats that differ in size and use. In an agricultural matrix, populations of small mammals were studied to assess effects of roads and corridors on movement and dispersal. During 52,416 trap nights and by tracking mammals dusted with fluorescent powder, we investigated frequency that animals crossed roads and irrigated crop circles. Sites bisected by wide roads with corridors had greater richness; whereas, sites divided by narrow roads with corridors had a significantly greater abundance of hispid cotton rats (Sigmodon hispidus). Based on our studies using powder-tracking, only reproductively active males of North American deermice (Peromyscus maniculatus) and western harvest mice (Reithrodontomys megalotis) moved significantly more along roads than away from or toward roads. Our results suggest that unfarmed crop corners are valuable habitat for wildlife; small mammals present may be impacted differentially by type of roadways that are present.
We developed a habitat model of urban-nesting Cooper's hawks (Accipiter cooperii) based on characteristics of nest sites in Tucson, Pima County, Arizona. We tested the model in three urban areas in southern Arizona. In Green Valley, the model correctly predicted expected occupancy at six of seven potential home ranges. However, we found no nest of Cooper's hawk at 4 and 16 sites in Casa Grande and Phoenix, respectively, with model-expected occupancy. No nest of Cooper's hawk was at any site in any of the three urban areas where our model predicted no occupancy. We speculate that high temperatures in the lower-elevation cities (Phoenix and Casa Grande) were beyond thermal tolerance of nesting Cooper's hawks.
The Pinaleño Mountains of southeastern Arizona contain the southernmost population of red squirrels (Tamiasciurus hudsonicus) in North America. Red squirrels historically inhabited the Guadalupe Mountains in Trans-Pecos Texas during the Pleistocene and the possibility that red squirrels currently persist has been suggested by several biologists visiting the upper-elevation forests. Herein, we report results of an assessment of small mammals in coniferous forest where we used observational line transects, playback calls, and live trapping to determine status of red squirrels. We surveyed 132 ha of coniferous forest along 8.9 km of transects and observed and found evidence of 10 species of mammals. We detected no evidence of red squirrels inhabiting high-elevation coniferous forest.
We used mixed-effects models to examine relationships of reproductive characteristics of the giant gartersnake (Thamnophis gigas) to improve population modeling and conservation planning for this species. Neonates from larger litters had lower mass, and mass of neonates also was affected by random variation among mothers. Length of mother did not affect relative mass of litters; however, our data suggest that longer mothers expended less reproductive effort per offspring than shorter mothers. We detected random variation in length of neonates among mothers, but these lengths were not related to length of mother or size of litter. Mean size of litter varied among years, but little evidence existed for a relationship between size of litter or mass of litter and length of mother. Sex ratios of neonates did not differ from 1∶1.
We evaluated predation on nests and methods to detect predators using a combination of infrared cameras and plasticine eggs at nests of American avocets (Recurvirostra americana) and black-necked stilts (Himantopus mexicanus) in Don Edwards San Francisco Bay National Wildlife Refuge, San Mateo and Santa Clara counties, California. Each technique indicated that predation was prevalent; 59% of monitored nests were depredated. Most identifiable predation (n = 49) was caused by mammals (71%) and rates of predation were similar on avocets and stilts. Raccoons (Procyon lotor) and striped skunks (Mephitis mephitis) each accounted for 16% of predations, whereas gray foxes (Urocyon cinereoargenteus) and avian predators each accounted for 14%. Mammalian predation was mainly nocturnal (mean time, 0051 h ± 5 h 36 min), whereas most avian predation was in late afternoon (mean time, 1800 h ± 1 h 26 min). Nests with cameras and plasticine eggs were 1.6 times more likely to be predated than nests where only cameras were used in monitoring. Cameras were associated with lower abandonment of nests and provided definitive identification of predators.
Little information is available on spiders in the Chihuahuan Desert. In the Jornada del Muerto of southern New Mexico, we collected ca. 120 species of spiders in the past 30 years. We report four state records and five potential undescribed species. A comparison of our list of species with those from three other areas in the Chihuahuan Desert (White Sands National Monument and vicinity and Valley of Fires near Carrizozo and vicinity, both in New Mexico, and an area near Big Bend, Texas) revealed low overlap, indicating that the regional spider fauna is still not fully known. Baseline knowledge of the spider fauna from several sites could serve as a criterion for assessing climatic change.
Pembroke Township, Kankakee County, Illinois, is part of an extensive glacial sand deposit. In this part of Illinois, some sand savannas retain much of their original natural character and they have high diversity; we detected 574 taxa of plants, including 11 state-listed endangered and threatened species. On five sites, we evaluated vegetation that varied from dry sand savanna to closed sand forest with Quercus velutina (black oak) dominating the overstory and Q. alba (white oak) the only other species of tree commonly encountered. Density of trees averaged 135.7 stems/ha, with an average basal area of 7.94 m2/ha on our five sites. Based on aerial photographs, the extent of woody overstory has more than doubled since 1939.
I observed 215 nesting events of Pseudemys texana (134) and Trachemys scripta (81) from 25 April to 14 July 2008 on a golf course in Hays County, Texas. For P. texana, 111 (82.8%) nested one time, 21 (15.7%) nested twice, and 2 (1.5%) nested three times. For T. scripta, 53 (65.4%) nested one time, 24 (29.6%) nested twice, 3 nested three times (3.7%), and 1 nested four times (1.2%). Both species had an internesting interval of ca. 30 days between first and second clutches. Subsequent internesting intervals were shorter but samples were not sufficient to address whether this was fortuitous. On their first attempt, 82% of P. texana and 78% of T. scripta completed nesting. Nesting was diurnal with most activity occurring before noon. Neither distance to nesting site from water nor number of days from the first nesting event to the next nesting event varied with length of plastron.
The dwarf palmetto, Sabal minor, reaches the northwestern limit of its geographic range in McCurtain County, Oklahoma, where it is critically imperiled. We determined that S. minor was more widespread than previously reported; 28 new localities were identified. Populations were associated positively with average annual minimum temperatures (i.e., plants were in the warmest parts of the county), negatively associated with elevation, and the species primarily occurred on silty clay soils. Although S. minor was common in a few areas near Red Slough Wildlife Management Area, it generally was uncommon and typically represented by only a few individuals. Ecological Niche Factor Analysis projected that suitable habitat was concentrated in southeastern McCurtain County, but that potentially suitable habitat was present throughout much of the county.
We studied demography of a population of viviparous lizard, Sceloporus bicanthalis, from Nevado de Toluca Volcano, Mexico, using mark-recapture methods. Age structure of this population varied seasonally due to an increase in number of juveniles over summer, although neonates were observed in every month. Estimated average density was 304 individuals/ha. Snout-vent length at sexual maturity in viviparous S. bicanthalis was 31 mm in males and 32 mm in females. Males survived longer than females, with an expected lifespan of 15 months, compared to 8 months for females. Net reproductive rate of this population was 1, suggesting it was at equilibrium, while generation time was 7 months. This high-elevation population has a semelparous life cycle.
Diversity of arthropods preyed upon by the carnivorous plant Pinguicula moranensis was analyzed during 2006 within a pine-oak (Pinus-Quercus) forest in the Sierra de Pachuca, Hidalgo, Mexico. A total of 570 individuals of nine orders was collected. Hemiptera was recorded as prey of this plant for the first time. The most prevalent order was Diptera, with 53.6% of total prey; within this order, Sciaridae accounted for 64.7% of prey. The month with the highest values for alpha diversity was July (H = 1.32). Greatest turnover of orders was June–November and that of families of Diptera was July–August. Total beta diversity was greater in families of Diptera, with a value of 1.29, while that of orders of arthropods was 0.53.
We examined nesting in Norops lionotus to describe nesting sites and to determine if nesting aggregations were by multiple females or repeated deposition of eggs by the same female. We also described eggs during incubation and the subsequent hatchlings. We collected eggs from nests along streams at Omar Torrijos National Park in central Panama and incubated them until they hatched. We located seven nests (six active, one inactive) containing 47 eggshells (2 depredated; 45 hatched) and 67 unhatched eggs. All nests were on the downstream side of large boulders covered by moss and herbaceous vegetation. Estimated minimum number of females using each nest was one to five, depending on assumptions of the estimate. Estimates indicated that nesting aggregations were a combination of multiple females nesting communally and repeated deposition of eggs by the same female. Hatchlings averaged 2.66 cm in snout–vent length, 4.60 cm in length of tail, and 0.42 g in mass, with no significant difference between males and females or among nests. Overall sex ratio for hatchlings was not significantly different from 1∶1.
We studied seasonal dietary patterns of Sceloporus jarrovii from a desert environment northwest of Gomez Palacio, Durango, Mexico. Stomach contents were examined (n = 82) and relative abundance and volume were determined. Formicids (ants) were the most abundant prey in all seasons. Other abundant foods were coleopterans (summer, winter) and isopterans (autumn, winter). Based on relative abundance in all seasons, S. jarrovii had a narrow breadth of diet, but relative volume of foods was broader. Overlap between sexes for relative abundance and volume was high throughout the year. However, low overlap in relative volume in spring indicated variation in diet between sexes. Three of the most common prey throughout the year varied significantly between sexes in length, width, and volume. However, volumes of the three most abundant foods were not correlated with snout–vent length of lizards.
Within the Great Basin, diversity of shrews (Soricidae) generally is low. We present information on distribution and ecology of shrews from the Ruby Mountains of northeastern Nevada, an area that is exceptional in supporting six species. The assemblage includes two habitat generalists and four species that are more ecologically specialized, three of which are poorly known. The high species richness of shrews in the Ruby Mountains reflects the large area, the ecological complexity, and the geographic overlap of several species.
This study examines effects of simulated echolocation calls of bats in a field setting on the flight activity and pheromone-tracking behavior of the male corn earworm moth, Helicoverpa zea (Lepidoptera: Noctuidae), an insect that responds evasively to echolocation calls of bats. Simulated echolocation was broadcast over crop fields in an area where moths were abundant during summer. Field collections of free-flying moths and pheromone trapping of male moths were conducted in the presence and absence of simulated calls. Numbers of moths captured were not affected in either experiment by presence of simulated echolocation calls. Contrary to previous evidence, these data suggest that moths are not dissuaded from tracking pheromones under a perceived high risk of predation. Exhibiting a continual anti-predator response under a sustained risk of predation could have negative impacts on reproductive success, leading males to take higher risks compared to situations in which predators are sporadically present.
Spawning behaviors of the Devils River minnow (Dionda diaboli) were observed in the Devils River, Val Verde County, Texas. Spawning in the wild was observed over active and inactive nests of centrarchids near openings of a spring. Nests consisted of cleaned gravel ca. 2–3 cm in maximum dimension. Males defended territories and occasionally spawned with receptive females over the nests. All behaviors observed in the laboratory were observed in wild fish and percentages of time that those behaviors were observed were similar.
A male Brazilian free-tailed bat (Tadarida brasiliensis), collected from a colony in Huntsville, Walker County, Texas, had severe periodontal disease resulting in extensive loss of teeth. Although demonstrating normal activity and a healthy appearance, this individual had only eight teeth: normal complement is 30–32 teeth. The remaining teeth appeared to be sufficient for this individual to adequately process food and maintain an average body weight as reported for this species.
We observed an increase in observations of black-tailed jackrabbits (Lepus californicus) within stands of mixed-conifer forest treated with fire. Stands were assigned to four experimental treatments: control, prescribed-fire only, mechanical only, and mechanical plus fire. Observations were recorded by cameras in July–August 2001–2003, with 2003 being the first post-treatment year. Three observations of black-tailed jackrabbits were recorded in 2001, four in 2002, and 37 in 2003. In 2003, 70% (26) and 16% (6) of observations were within the fire-only and mechanical-plus-fire treatments, respectively. A combination of increased openness of understory and overstory and new growth of forage may account for observed increases within burned stands.
We report for the first time aggregation behavior in the lizard Sceloporus minor. The behavior was recorded at Galeana, Nuevo León, Mexico, where a group of ca. 30 individuals were observed under a rock associated with a stone wall. Weight, sex, snout-vent length, and total length were recorded for 22 individuals. Means of traits were: males—weight = 18.9 g, snout-vent length = 80.5 mm, total length = 173.3 mm; females—weight = 13.9 g, snout-vent length = 72.9 mm, total length = 161.1 mm. Sex ratio was 16 males∶6 females. Our observation extends the known elevational range of the species from ca. 3,000 m to 3,470 m.
We evaluated the influence of environmental temperature and phenotype on thermoregulation by Sceloporus palaciosi, a diurnal iguanid lizard from high elevations in central Mexico. Range of body temperature was 13–36°C with a mean of 27.82 ± 5.31°C. Active lizards had a higher body temperature than inactive ones. After removal of state of activity from analysis, sexes did not differ in body temperature. Body temperature was significantly correlated with temperature of air and substrate in both active and inactive lizards.
We investigated the influence of sex and depth of body on escapes from hoop nets by red-eared sliders (Trachemys scripta) to assess if escapes from traps potentially biased estimates of structure of populations. Turtles remained in traps ≥34 h and traps were checked at ca. 12-h intervals. Depth of body was not a significant variable in escapes from hoop nets, but sex was a significant variable, with only females escaping. This study provides evidence that previous reports on the inefficiency of hoop nets and on rates of captures that are male-biased could result from escapes rather than differential attraction to traps.
Jennifer L. Newby, Jacob Boling, John Estes, Laura K. Garey, Andrea M. Grelle, Julie Hasken, Rory McKee, Anthony Wilmes, Chad E. Montgomery, Michael I. Kelrick, James M. Walker
The diploid, parthenogenetic, whiptail lizard Aspidoscelis tesselata is represented by two distinctive variants of color pattern in southeastern Colorado. Pattern-class C has been recorded from several sites in the canyonlands of Otero, Las Animas, and Baca counties and D has been recorded from four sites north of the Purgatoire River near Higbee, Otero County. We report a specimen of A. tesselata D collected in 2008 south of the Purgatoire River in Las Animas County, which represents a significant range extension for this distinctive parthenogen.
I collected larvae of Eutrombicula alfreddugesi for the first time parasitizing Gerrhonotus infernalis, Sceloporus poinsetti, S. jarrovii, and S. grammicus as new host records for Coahuila, Mexico. Lizards were collected in the submontane scrub of the Sierra de Jimulco, Coahuila, Mexico. In G. infernalis, there was a large number of mites in small groups, primarily along the flanks protected by the granular fold. All species of Sceloporus had mites in the neck region grouped behind the eardrums and protected by lateral gular folds. Type of vegetation and available substrates in this part of the Sierra de Jimulco create microhabitats that can support this mite.
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