Condition models for wintering Northern Pintails in the Southern High Plains

Three condition models for wintering Northern Pintails ( Anas acuta ) were tested for their ability to predict fat mass, logarithm of fat mass, or a condition index (CI) incorporating fat mass. Equations generated to predict fat mass and the logarithm of fat mass accounted for more than 69% of the variation in these dependent variables. Log transformations of body mass, wing length, and total length explained at least 60% of the variation in CI. All models performed better on an independent data set. Mean prediction error was minimal (≤8% of measured variables) and negative for all models. Regression models apply to live and dead pintails and thus represent tools that have utility in a wide variety of studies on pintail condition.     

Genetic structure in striped skunks ( Mephitis mephitis ) on the Southern High Plains of Texas

Genetic variation within populations reflects population-level social and demographic processes and influences how a population behaves as an evolutionary unit. We examined partitioning of genetic variation in striped skunks ( Mephitis mephitis ) from the Southern High Plains of Texas during 1994-1995. Sixty-nine male and 35 female skunks were sampled on four 12.8-km 2 study plots. Plot centers ranged from 17.6 to 61.6 km apart. We used multi-locus DNA fingerprinting with 2 probes, pV47 and CTTxAGG, to test 3 hypotheses: (1) females are more genetically similar to other females than males are to other males on the same plot (indicating greater female philopatry than male philopatry), (2) genetic similarity is greater within plots than among plots (indicating partitioning of genetic variation in space), and (3) genetic similarity of males decreases as the distance separating males increases (indicating geographic distance affects rates of gene flow). In general, males on a plot had lower average genetic similarity than females. Genetic similarity within plots was not different from genetic similarity among plots for males or for females. Genetic similarity of males did not decrease with increasing distance among plots. The lack of geographical genetic structure in striped skunks suggests at the scale of this study (< 60 km) that gene flow of biparentally inherited genes is not distance-mediated. However, the higher similarity values for females than for males on the same plot supports an effect of male-biased dispersal and female philopatry on partitioning of genetic variation between sexes.     

Association of black-tailed prairie dog colonies with cattle point attractants in the Northern Great Plains

In October 1991 we recorded all black-tailed prairie dog ( Cynomys ludovicianus ) colonies and cattle points in a 1248-km 2 study area in southwest North Dakota and southeast Montana. Cattle point attractants were defined as fabricated water tanks and long-term supplemental feed sites. We found that a signivicant number of prairie dog colonies encompassed or adjoined cattle point attractants ( p < .001). Prairie dog colonies associated with cattle point attractants were a mean distance of 1.0 km from the next nearest town. The existence of cattle point attractants may encourage prairie dog colonization. Conversely, refraining from using long-term cattle point attractants can discourage prairie dog colonization.     

Waterfowl and shorebird use of surface-mined and livestock water impoundments on the Northern Great Plains

Cluster analysis and stepwise discriminant analysis were used to group waterfowl and shorebird use on water impoundments (bentonite, coal, livestock) on the Northern High Plains. Three bird-use categories—high, medium, and low—were delineated by these analytical procedures. Eleven physical, chemical, and biological parameters of impoundments were related to bird use; water area, nitrogen, and low basin slopes were found to be important parameters in estimating bird use on impoundments. Spring and summer were the best seasons for surveying waterfowl and shorebird water impoundment use.     

Seasonal habitat use and selection of Chukars in west central Idaho

We examined radio-marked Chukar ( Alectoris chukar ) habitat use and selection in west central Idaho during spring and summer of 1995 and 1996. Use of habitats also was compared with abundance and distribution of yellow starthistle ( Centaurea solstitialis ), an exotic species that is increasingly abundant in Chukar habitats. During summer Chukars used areas of southeast aspect 12% less ( P = 0.002) and areas of northwest aspect 11% more ( P = 0.008) than in spring. Chukars also used areas that averaged 9% steeper slopes ( P P = 0.054) in summer than in spring. Shrub cover types were used 22% more ( P P P P P < 0.05) than expected, implicating the detrimental effects of this exotic plant on habitat use of Chukars.     

Use and selection of brood-rearing habitat by Sage Grouse in south central Washington

Sage Grouse ( Centrocercus urophasianus ) brood-habitat use was examined during 1992 and 1993 at the Yakima Training Center in Yakima and Kittitas counties, Washington. During the 2 yr we followed 30 broods, of which 12 persisted to 1 August (￣ x = approximately 1.5 chicks/brood). Food forb cover was greater at all brood locations than at random locations. Hens with broods in big sagebrush/bunchgrass habitat ( Artemisia tridentata/Agropyron spicatum ) selected for greater food forb cover, total forb cover, and lower shrub heights; broods in altered big sagebrush/bunchgrass habitats selected greater tall grass cover and vertical cover height; broods in grassland showed no preference for any measured vegetation characteristics. During the early rearing period (post-hatching-6 wk) each year, broods selected sagebrush/bunchgrass. Broods in 1993 made greater use of grasslands than in 1992 and selected grassland during the late brood-rearing period (7-12 wk). Broods selected for sagebrush/bunchgrass during the midday, but 52% of brood locations in the afternoon were in grassland. Tall grass cover was greater at morning (0500-1000 h) and afternoon (1501-2000 h) brood locations than at midday (1001-1500 h) and random locations. Midday brood locations had greater shrub cover and height than morning and afternoon locations. Selection of habitat components was similar to the results of other studies, but habitat conditions coupled with a possible lack of alternate brood-rearing cover types resulted in low survival of chicks.     

Bird community composition in relation to habitat and season in Betatakin Canyon, Navajo National Monument, Arizona

Bird species density, diversity, and species richness in relation to habitat and seasonal variations were studied in the Betatakin Canyon area of Navajo National Monument, Arizona. The two most prominent habitat types are a riparian forest deep in the canyon bottom and a mature pinyon-juniper woodland on the mesas and slopes above the canyon. One hundred thirty-five species of birds were encountered during the study and recorded by season and habitat. The avifauna assemblages demonstrate definite habitat selection into groups associated with the riparian and pinyon-juniper woodland communities. Diversity, density, and species richness were greatest in the riparian habitat during the spring and summer months. The differences in bird community composition were greater between seasons than between habitats. Pinyon pine and Gambel oak were highly selected as perch sites in the pinyon-juniper and riparian areas, respectively.     

Winter habitat selection patterns of Merriam's turkeys in the southern Black Hills, South Dakota

In northern areas of their expanded range, information on Merriam's turkeys ( Meleagris gallopavo merriami ) is lacking, specifically pertaining to wintering behavior and factors associated with winter habitat selection. Forest managers need detailed quantification of the effects of logging and other management practices on wintering habitats needed by Wild Turkeys and other wildlife. Therefore, we examined winter habitat selection patterns within ponderosa pine ( Pinus ponderosa ) forests and determined factors associated with use of farmsteads by Merriam's turkeys in the southern Black Hills, South Dakota. We radio-marked 86 female Merriam's turkeys (70 adults and 16 yearlings) and monitored them during winter (1 December–31 March), 2001–2004. Female Wild Turkeys used recently burned pine forest less than expected but selected farmsteads and stands of mature ponderosa pine ( 22.9 cm diameter at breast height [DBH] trees) for foraging sites. Within forests, female Wild Turkeys selected foraging sites with less understory vegetation and visual obstruction, and larger-diameter ponderosa pine. Ponderosa pine seed abundance varied among years, and pine seeds were most abundant in stands of 30–35 cm DBH with basal area of 22–28 m2 ? ha–1. Abundance of pine seeds may have influenced use of farmsteads by Wild Turkeys, more so than ambient temperatures or snow depth. In the southern Black Hills, management should emphasize open- to mid-canopy and mature-structural-stage pine stands, where seed production was greatest. During winters when mast from pine is unavailable, farmsteads likely provide nutritional supplementation and may be important for maintaining Merriam's turkey populations.     

Effects of anthropogenic land use on Odonata in playas of the Southern High Plains

Playas are ephemeral wetlands that are the only source of aboveground freshwater in the southern Great Plains, making them of vital importance to aquatic and amphibious animals. Playas are also highly threatened from anthropogenic land use (chiefly agriculture, which decreases hydroperiod through increased sedimentation). We examined community structure of adult odonates (dragonflies and damselflies) in playas differing in the 2 main regional forms of surrounding land use (cropland vs. grassland). Analysis of odonate diversity revealed high overlap between cropland and grassland playas. Traditional species-area theory did not fit observed patterns, as there appears to be a threshold playa size that supports maximal odonate diversity; this nonlinear response may reflect a tradeoff between hydroperiod and availability of emergent vegetation that is required for perching and oviposition. Since agriculture effectively reduces playa depth but not size of the overall playa watershed, this may mean that cropland playas serve as "ecological traps." This property has important implications for regional odonate diversity.     

Morphology of the alimentary tract in relation to diet among gobioid fishes

Summary

The morphology and general course of the alimentary canal, the relative length, number and morphology of the gill rakers, and the pattern of the buccal and pharyngeal dentition in 20 species of gobioids belonging to 3 families are studied. The food of the species studied is analysed from gut contents. Depending on the predominance of different food items in the gut the fishes can be categorized into herbivores feeding on algae, omnivores on algae, crustaceans or fish any of which may be dominant and detritivores on soft benthic ooze. The morphology of the alimentary canal, the R.L.G., the morphology of the gill rakers and the pattern of buccal and pharyngeal dentition are found to be related to the food of the fishes.     

Relating soil chemistry and plant relationship in wooded draws of the northern Great Plains

Soils of the green ash/chokecherry habitat type in northwestern South Dakota were evaluated for 22 properties to determine whether any could be correlated with density of chokecherry ( Prunus virginiana ) and snowberry ( Symphoricarpos occidentalis ). Surface soils were moderately fertile, with high levels of all elements except phosphorus and nitrogen. Soils were fine textured with moderately high cation exchange capacity and saturation percentages. However, soils were nonsaline-nonalkaline with low amounts of exchangeable sodium. None of the soil properties showed good correlation with chokecherry and snowberry densities. Greatest correlations were found between each of the shrub species and grass.     

Evaluating lek occupancy of Greater Sage-Grouse in relation to landscape cultivation in the Dakotas

Greater Sage-Grouse ( Centrocercus urophasianus ) have been declining in many states and provinces of North America, and North and South Dakota hold no exception to these declines. We studied effects of cultivated land on Greater Sage-Grouse lek abandonment in North and South Dakota. Landscape-level data were assessed using satellite imagery within a geographic information system. Comparisons were made of 1972-1976 and 1999-2000 percent cultivated and noncultivated land. These comparisons were made between land uses surrounding active leks versus inactive leks, active leks versus random locations, and abandoned regions versus active regions. The 1999-2000 imagery illustrated that percent cultivated land was greater near abandoned leks (4-km buffers) than near active leks in North Dakota or random sites, but this did not hold true in South Dakota. Comparison of an extensive region of abandoned leks with a region of active leks in North Dakota illustrated a similar increase as well as dispersion of cultivation within the abandoned region. However, 1972-1976 imagery revealed that this relationship between percentage of cultivated land and lek activity in North Dakota has been static over the last 30 years. Thus, if the decline of Greater Sage-Grouse is the result of cultivated land infringements, it occurred prior to 1972 in North Dakota.     

Status and conservation of salmonids in relation to hydrologic integrity in the Greater Yellowstone Ecosystem

Native salmonid status was evaluated with an index quantifying distribution and abundance of cutthroat trout ( Oncorhynchus clarki ) and grayling ( Thymallus arcticus ) in 41 watersheds comprising the Greater Yellowstone Ecosystem. We assessed hydrologic integrity with a percentile-based index measuring cumulative effects of reservoirs, surface water withdrawals, and consumptive water use. Status of native salmonids was poor in 70% of the watersheds; exceptions occurred in a north-south core extending from the Upper Yellowstone southward through the national parks to Bear Lake. Hydrologic integrity was highest in headwater areas and lowest in lower-elevation watersheds. Status of native and nonnative salmonid populations currently existing in the ecosystem was positively correlated with hydrologic integrity ( r = 0.58), indicating that the hydrologic index performed well on a watershed scale in quantifying suitability of stream environments for salmonids. However, native trout status and hydrologic integrity were similarly correlated ( r = 0.63) only when watersheds receiving the lowest possible native salmonid index score were removed from analysis because these watersheds were uniformly distributed across hydrologic integrity. We infer that nonphysical factors such as interactions with introduced fish species have played an important role in the disappearance of native salmonids. The highest priority for conservation is preservation of core watersheds, where both hydrologic integrity and native trout status are high. Restoration opportunities exist in the Teton, Idaho Falls, Willow Creek, Central Bear, and Bear Lake watersheds, where viable cutthroat trout populations remain but are threatened by habitat degradation.     

Vegetation patterns in relation to slope position in the Castle Cliffs area of southern Utah

Vegetation patterns in relation to slope position were studied on four foothill knolls in the Castle Cliffs area of Washington County, Utah. Study plots were established at four different slope positions: ridge top, upper slope, lower slope, and floodplain. Exposed rock was highest on the ridge top; exposed soil was highest on the floodplain; soil depth increased downslope. Plant life form varied with respect to slope position. Grass, annuals, and cryptogamic crust cover was highest on the ridge top and shrubs were most prominent on the midslope. Forb cover gradually increased downslope. Succulents were restricted to the ridge top or floodplain. Species distribution was distinct and strongly correlated to slope position. Two sets of congeneric species showed strong patterns of niche separation. The vegetation of the slopes is highly distinct at the ridge top and floodplain and grades toward the midslope from both ends. &nbsp;&nbsp;&nbsp;     

Environmental factors in relation to the salt content of Salicornia pacifica var. utahensis

The stability of the salt content in Salicornia pacifica Standl. var. utahensis (Tidestrom) Munz in relation to environmental changes was investigated. Salicornia pacifica communities have a characteristic soil pH of 7.5 to 8.0 &plusmn; 0.2 and a constant subsurface soil moisture level of 25 to 35 percent. The ion content in the tissue of S. pacifica remained constant despite increased moisture stress throughout the growing season. The concentrations of the salts were significantly higher in the surface soil layers than in the subsurface layers around the roots. Normal metabolic processes in the tissues of S. pacifica appear to occur even though some fluctuations in the ionic balance and concentration of ions in the plant occur.     

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.     

Denning habitat and diet of the swift fox in western South Dakota

Swift fox ( Vulpes velox ) were investigated in western South Dakota to determine food habits and denning site characteristics. Over a three-year period food habits consisted of mammals (49%), followed by insects (27%), plants (13%), and birds (6%). Dens were located near hilltops within two habitat types, shortgrass and midgrass rairie; each type is characterized by differing plant species. Soil type was not a selective factor for den sites of swift fox. Management considerations for enhancing swift fox populations are presented.