Lizards and turtles of western Chihuahua

This second report on the reptiles of Chihuahua deals with the lizards and turtles of western Chihuahua. Field work was done from 1956 to 1972 and was confined to the area west of Highway 45. General information pertaining to the ecology and geology reported in the section on snakes is not repeated. Ecological and life history information is included in the species accounts where data are available. In western Chihuahua 16 genera and 49 species and subspecies of lizards and 3 genera and 5 species of turtles are reported. Only one subspecies is described as new ( Sceloporus poinsettii robisoni ), and added data strengthen the diagnosis of others. Three genera ( Sceloporus, Cnemidophorus, and Eumeces ) contain 28 of the species and subspecies reported.     

An unusual ecology among whiptails: the case of Cnemidophorus lacertoides from a restinga habitat in southern Brazil

We studied the ecology of Cnemidophorus lacertoides at a restinga habitat in southern Brazil. Peak activity occurred between 12.00 and 15.00. The mean body temperature of active lizards (35.0 ± 2.9°C) was relatively low compared with other whiptails and was significantly influenced by environmental temperatures. Mean snout–vent length and mean body mass of individuals were 56.5 mm and 4.4 g, respectively. Male and female C. lacertoides were not significantly different in body size. Cnemidophorus lacertoides consumed 12 types of prey, with ants and spiders being the most important items. Unexpectedly, lizards did not consume termites, which tend to be very important items in the diets of most whiptails. We conclude that the population of Cnemidophorus lacertoides we studied deviates from the typical whiptail ecology because many of its ecological features differ from those of most other cnemidophorines of similar size.     

Reproduction in three sympatric lizard species from west-central Utah

Data on reproduction by the lizards Uta stansburiana, Crotaphytus collaris, and Cnemidophorus tigris are presented from a community where they are sympatric in west-central Utah. Data are compared to a previous study of these species at the same site and to data from other sites in the United States.     

Species-habitat relationships in an Oregon cold desert lizard community

The abundance and diversity of lizards in nine habitat types from Oregon were studied from May through October 1980. Eight species were from eight habitat types. The most common species were Sceloporous occidentalis, Uta stansburiana, Sceloporous graciosus, and Cnemidophorus tigris. Phynosoma douglassi was uncommon and Eumeces skiltonianus was not observed. Temporary streams in nonbasaltic areas were the most productive habitat m terms of lizard abundance but sagebrush areas were the most productive habitat in terms of species diversity.   No lizards were recorded from grassland conversion areas. The conflict between a land management policy that emphasizes both vegetation conversion and conservation of present wildlife stocks is discussed.     

Food habits of the western whiptail lizard ( Cnemidophorus tigris ) in southeastern New Mexico

This study presents the first food habit assessment for the western whiptail lizard ( Cnemidophorus tigris ) in the shinnery oak – mesquite habitat ( Quercus havardii – Prosopis glandulosa ) of southeastern New Mexico. Short-horned grasshoppers, termites, antlions, beetles, and spiders formed the major portion of the diet during the four-year study. Discriminant analyses were used to evaluate annual, seasonal (monthly), and sexual variation. Incidental food categories were responsible for most of the annual and seasonal variation. Dominant foods varied little between months and years. Sexual variation was more evident; it may act to reduce intraspecific competition for food resources and may be associated with secondary sexual size dimorphism.         

The northward extension of reptiles in the Palearctic,with the Jordan Valley (Israel) as a model: snakes outrace lizards (Reptilia: Squamata)

The geographical distribution of reptiles is known to be climate dependent. Our analysis of literature data from the Palearctic confirmed that snakes, as a group (186 species), tend to extend further to the north, into cooler climate, than lizards (460 species). This has also been reported for the Nearctic. On a smaller scale, as a model, we investigated the expansion of reptiles from the warm southern desert of Israel northwards along the Jordan valley into cooler climate, based on 587 locality records of 17 species. It transpired that the snakes significantly extend further to the north than the lizards, paralleling and exemplifying the global scale. The ability of snakes to inhabit relatively cooler climates appears to accord with three physiological traits of snakes: lower optimal body temperatures, absence of temperature-dependent sex determination, and ability to thrive on infrequent meals.     

Conservation in a changing landscape: habitat occupancy of the critically endangered Tennent’s leaf-nosed lizard (Ceratophora tennentii) in Sri Lanka

Landscape modification is a key driver of global species extinction. Thus, understanding how species react to changes is essential for effective conservation management in modified landscapes. We examined the impact of selected land use patterns on the critically endangered Ceratophora tennentii in the Knuckles mountain range of Sri Lanka where lizards occupy patches of both natural undisturbed forests and modified plantations – evidently, those with a forest canopy. We tested three potential explanations for non-random habitat selection: availability of suitable microhabitat pockets, availability of prey and direct threats from humans. The microhabitat pockets occupied by the lizards were characterised by shade, humidity and the density of perches. Most lizards were found in mixed cardamom forests followed by natural forests and cardamom plantations, but none were observed in the pine plantations. Food availability showed similar patterns among habitats. Direct mortality by humans did not influence the distribution of this species. Our work indicates that habitat modifications that retain the structural complexity of the vegetation would still permit the existence of the species in densities equal to or greater than that of undisturbed forest patches. It adds to a growing body of literature that signifies the importance of disturbed habitats (intermediate disturbance hypothesis) in protecting threatened species of fauna. It is highly unlikely that some disturbed habitats will be ever be returned to their former pristine state in time frames that are important for species’ conservation. Hence, attention is needed in developing suitable approaches to manage and conserve species across disturbed habitats.     

Homing in eastern fence lizards ( Sceloporus undulatus ) following short-distance translocation

We conducted an experiment on eastern fence lizards ( Sceloporus undulatus ) during August-September 1995 near Los Alamos, New Mexico, (1) to ascertain if lizards that were relocated short distances exhibited homing, (2) to investigate a possible barrier to movement, and (3) to determine the effect of translocating individuals from a transplant area on lizards in a recipient area. We relocated 15 of an estimated population of 39 (95% CI 36-45) lizards an average distance of 46 m. Fourteen of 15 translocated lizards returned to within 6.81 ( s ￣x = 1.43) m of the original capture location. Movement distances did not vary ( F = 0.76; 1,53 df; P = 0.381) between resident and translocated lizards during the pretreatment period and did not vary for resident ( F = 2.86; 1,12 df; P = 0.1166), but varied between pretreatment and posttreatment periods for translocated ( F = 14.65, 1,7 df, P 0.0065) lizards. Translocated lizards did not affect the resighting probability of resident lizards ( F = 0.96; 1,14 df; P = 0.34), but this may be related to low power (1 — β = 0.15) and translocated lizards moving out of the area quickly.     

Leaf area ratios for selected rangeland plant species

Leaf area estimates are required by hydrologic erosion, and growth/yield simulation models and are important to the understanding of transpiration interception, CO 2 fixation, and the energy balance for native plant communities. Leaf biomass (g) to leaf area (mm 2 ) linear regression relationships were evaluated for 15 perennial grasses, 12 shrubs, and 1 tree. The slope coefficient (β 0 ) of the linear regression equation is a ratio of leaf area to leaf biomass and is defined as the leaf area ratio [LAR = one-sided leaf area (mm 2 )/oven-dry leaf weight (g)]. LAR represents β 0 in each regression equation, where Y = β 0 (X). Linear regression relationships for leaf area were computed ( r 2 = .84-.98) for all 28 native range species after full leaf extension. Within-plant estimates of leaf area for mesquite ( Prosopis glandulosae Torr. var. glandulosae [Torr.] Cockll.) or lime prickly ash ( Zanthoxylum fagara [L.] Sarg.) were not significantly different ( P ≤ .05). LARs for three of the shrubs and the tree were established at four different phenological stages. There were no significant differences ( P ≤ .05) in LARs for lime prickly ash, mesquite, and Texas persimmon ( Diospyros texana Scheele) after full leaf extension during the growing season. The LAR relationship for Texas persimmon changed significantly after full leaf extension. LAR relationships for Texas colubrina ( Colubrina texensis [T. & G.] Gray) changed in response to water stress.     

Occurrence and habitat use of passage neotropical migrants in the Sonoran Desert

Little is known about stopover habitat use by neotropical migratory birds in the deserts of North America. We determined distribution, abundance, and habitat associations of neotropical migrants during spring migration in the Sonoran Desert of southwestern Arizona along large washes that supported xeroriparian scrub vegetation. We detected 91 bird species during surveys, 50 (52%) of which were passage neotropical migrants. Although xeroriparian scrub covered less than 55% of the area surveyed, 97% of all detections of passage migrants were from this vegetation type. By calculating habitat breadth for each species, we classified 87% of passage migrants as xeroriparian specialists. Richness of passage migrants was strongly associated with the presence of overstory (> 2.5 m) mesquite and paloverde. The highest species richness of breeding neotropical migrants was associated with width of the xeroriparian corridor. Habitat characteristics we have shown to be important to neotropical migrants can be preserved and managed by protecting xeroriparian areas, particularly those supporting mature (> 2.5 m) paloverde, mesquite, desert willow, and catclaw acacia trees. Additionally, xeroriparian scrub within the creosote-bursage vegetation type may be particularly important to passage neotropical migrants.     

The New Mexico whiptail, Cnemidophorus neomexicanus (Squamata: Teiidae), in the Great Basin of north central Utah

We report the discovery of established populations of Cnemidophorus neomexicanus in the Salt Lake City area. These are the 1st records of this species in Utah and in the Great Basin and are far from all other known populations of the species. We conclude that C. neomexicanus was introduced in the Salt Lake City area, perhaps within the last 30 years.     

Response of reptile populations to different land management practices on the Idaho National Engineering Laboratory Site

Populations of reptiles were examined in grazed and ungrazed habitats dominated by sagebrush ( Artemisia tridentata ) or by crested wheatgrass ( Agropyron cirstatum ) on the Idaho National Engineering Laboratory (INEL) Site in southeastern Idaho. The sagebrush lizard ( Sceloporus graciosus ) and the short-horned lizard ( Phrynosoma douglassi ) were the only species of reptiles encountered in sufficient numbers to permit statistical analysis. Both of these species preferred sagebrush habitats to areas dominated by crested wheatgrass. The sagebrush lizard was most abundant in the native, ungrazed, sagebrush habitat, and the short-horned lizard was most plentiful in the sheep-grazed area dominated by big sagebrush.     

Terrestrial vertebrate fauna of the Kaiparowits Basin

This report includes data collected during an investigation by Brigham Young University personnel from 1971 to 1976, as well as a literature review. The fauna of the Kaiparowits Basin is represented by 7 species of amphibians (1 salamander, 5 toads, and 1 tree frog), 29 species of reptiles (1 turtle, 16 lizards, and 12 snakes), 183 species of birds (plus 2 hypothetical), and 74 species of mammals. Geographic distribution of the various species within the basin are discussed. Birds are categorized according to their population and seasonal status. Avian habitat relationships are discussed, and extensions of range are reported for 5 species of birds. Three threatened or endangered avian species occur in the basin. Four avian species seem to have declined significantly in numbers in recent years.     

Effects of habitat disturbance on diets of Great Horned Owl ( Bubo virginianus ) in a cold desert

To determine the potential effect of habitat disturbance, Great Horned Owl ( Bubo virginianus ) diets were quantified in disturbed and undisturbed habitats over a 2-year period at Dugway Proving Ground in the Great Basin Desert of Tooele County, Utah. Invertebrates were the most abundant prey by count, whereas mammals constituted the majority of diet by biomass. Species richness in the diet did not differ between habitats or among seasons after correcting for the number of pellets in each sample. However, the number of vertebrate species was greater than the number of invertebrate species in the diet, and this ratio differed between disturbed and undisturbed habitats. Invertebrate species made up a greater proportion of total species richness in the diet in the undisturbed than the disturbed habitat. Nineteen species occurred in the diet in only 1 of the 2 habitat types (7 unique species in disturbed habitat, 12 unique species in undisturbed), but all such species were rare and contributed little both by count and biomass to the overall diet. Of the 20 most important species found in owl diets in both habitats (based on percent biomass), none were more common in 1 habitat than the other after correcting for multiple tests. Although there were minor differences in the diet between disturbed and undisturbed habitats, habitat alteration and degradation of native vegetation on Dugway Proving Ground did not affect the major components of the diet of Great Horned Owls.     

Soil depth effects on Chihuahuan Desert vegetation

We evaluated relationships between soil depth and vegetation standing crop components over a 3-year period on 3 adjoining pastures with similar size, vegetation, and soils on the Chihuahuan Desert Rangeland Research Center in south central New Mexico. Soils on our study pastures are primarily light sandy loams varying from a few centimeters to 1 m or more in depth underlain by a calcium carbonate layer. Study pastures were ungrazed in 1995 and 1996 and conservatively grazed in 1997. Linear regression equations using perennial grass standing crop (kg ha -1 ) and honey mesquite ( Prosopis glandulosa Torr.) cover (%) as dependent variables and soil depth as the independent variable were significant ( P P = 0.78, n = 18), but a significant ( P = 0.01) negative correlation occurred on deep soils ( r = -0.67, n = 15). Perennial grass standing crop differed greatly among years when data were pooled across pastures, ranging from 64 kg ha -1 in 1995 to 248 kg ha -1 in 1997. Our study shows that soil depth has a major influence on Chihuahuan Desert vegetation. Perennial grasses are favored by shallow sandy soils while deep sandy soils favor honey mesquite.     

Competition Between Adult and Seedling Shrubs of Ambrosia dumosa in the Mojave Desert, Nevada

Seeds of the perennial shrub Ambrosia dumosa germinated in abundance following 11 days of rain during August 1983 at a study site in the northern Mojave Desert. Seedling establishment, growth, and reproduction were observed in natural vegetation and in an area that had been previously cleared of vegetation. For 5,527 A. dumosa seedlings, percent survival in April 1986 averaged 3% in the undisturbed vegetation and 58% in the denuded area. Seedlings occupying the cleared area had grown to sizes up to 0. 1 m 3 m by October 1984; some produced flowers and fruit in the spring of 1985. Surviving seedlings in the undisturbed vegetation were all smaller than 0.001 m 3 and did not reproduce. These pronounced differences in growth, survival, and reproduction associated with the presence or absence of adult shrubs demonstrated an intense competition that is incompatible with indications of mild competition from nearest-neighbor analyses. I therefore hypothesize that competition for water occurred, not by competition for water in two dimensions but by rapid use of a common resource, as if several people were drinking with straws from a common cup. This temporal mechanism would strongly favor adults over seedlings.     

Terrestrial vertabrates of Scotts Bluff National Monument, Nebraska

A survey of terrestrial vertebrates was conducted at the Scotts Bluff National Monument (SBNM), Nebraska, to determine species composition, relative abundance, and distribution by habitat of the existing amphibians, reptiles, birds, and mammals. Various sampling methods were used to detect animal species richness and to estimate population densities. The seven major habitat types at SBNM contained 4 species of amphibians, 8 reptiles, 96 birds, and 28 mammals. The only endangered or threatened species observed was a dead bald eagle ( Haliaeetus leucocephalus ). The racer ( Coluber constrictor ) and prairie rattlesnake ( Crotalus viridis ) were the two most abundant snakes. The prairie falcon ( Falco mexicanus ) was a common raptor that nested in Scotts Bluff. Sympatric populations of mule deer ( Odocoileus hemionus ) and white-tailed deer ( Odocoileus virginianus ) appeared to be hybridizing. The riverine woodland contained the greatest number of fauna species with only 4% surface area of SBNM. Sharp-tailed grouse ( Tympanuchus phasianellus ) and pronghorn antelope ( Antilocapra americana ), absent from the Monument, are two potential native species for reintroduction.     

Understory seed rain in harvested pinyon-juniper woodlands

Seed rain was collected on six paired tree harvest and undisturbed plots in singleleaf pinyon ( Pinus monophylla )–Utah juniper ( Juniperus osteosperma ) stands. Approximately 14,600 seeds were collected during four years. Seed rain in undisturbed plots was similar to levels in mixed forest communities. Seed rain on harvest plots was similar to disturbed sites and grasslands. Seed rain levels reflect the current successional stage rather than the climax community type for the site. Seed rain increased in numbers and seed production per unit of plant cover following tree removal and especially on transition soil microsites. Only three to four of the plant species present on a site contributed greater than 10% of the total seed rain. Seed rain composition was similar on harvest and undisturbed plots (Jaccard Similarity Index Values = 47% to 67%) and explains in part the rapid reestablishment of predisturbance understory communities.     

Thermal ecology,activity pattern,habitat, and microhabitats used by the skink Mabuya arajara (Squamata: Scincidae) in the Araripe Plateau,northeastern Brazil

ABSTRACT

We evaluated the activity period, thermal ecology, habitats, and preference for microhabitats of the skink Mabuya arajara in a humid forest environment on the slope of the Araripe Plateau, Brazil. A total of 283 lizards were observed. The lizards were found to be diurnally active (unimodal type pattern), with peak activity during the hottest hours of the day (1100 to 1200). About habitat use, the majority of individuals (73.8% N = 209) were recorded in the narrow transitional area, in the edges of the forest; while 26.4% of individuals were observed in open areas and no observations were made in dense forest. Seven different types of microhabitats were used, with fallen palm leaves (Arecaceae) being the preferred (47.7% N = 135). Considering all lizards, microhabitat niche breadth was 3.27. Males and females presented a high overlap (0.95) in microhabitat use. The average T_c recorded for M. arajara was 32.06 ± 2.72°C. Body size (SVL) did not influence body temperature (F = 0.51, P = > 0.05). Most of the animals were observed with their bodies completely exposed (67.84%, N = 192), 18.37% (N = 52) were semi-exposed and 13.79% (N = 39) were in shelters. Among animals with some degree of sunlight exposure, 57.59% (N = 163) were in shadows, 25.10% (N = 71) were under sunlight filtered by vegetation, and 17.31% (N = 49) were under direct sunlight.A review of the ecology of Mabuya spp. shows that several features appear to be conserved among members of the genus.     

Capture rates of reptiles and amphibians on black-tailed prairie dog ( Cynomys ludovicianus ) colonies and on uncolonized prairie in Colorado

Prairie dog eradication negatively affects dependent wildlife. Assessing the effects of prairie dog activities on reptiles and amphibians may depend upon the efficacy of trapping designs. We compared capture rates of reptiles and amphibians on black-tailed prairie dog ( Cynomys ludovicianus ) colonies and on adjacent uncolonized short-grass prairie, using funnel traps and pitfall traps with drift fences, as well as ground captures. We captured 152 reptiles and amphibians representing 10 species. We captured 51.3% of all reptiles and amphibians on colonies, compared to 48.7% from uncolonized sites. Overall, captures of reptiles and amphibians were similar on colonies and uncolonized sites for all capture methods combined. We achieved higher capture rates on uncolonized sites using funnel traps and pitfall traps but higher capture rates on colonies for ground captures. For all years on all sites combined, we captured significantly more animals in funnel traps (52.6%), surpassing pitfall trap captures (23.0%) and ground captures (24.3%). We recommend using multiple Y-shaped drift fence arrays ≥7.6 m in length, funnel traps with double-ended openings, and black-colored pitfall traps with opening diameters ≥30 cm.