Distribution of the eastern woodrat ( Neotoma floridana campestris ) in southern Nebraska

The eastern woodrat ( Neotoma floridana ) occurs throughout eastern and central parts of the United States. In Nebraska, 3 of 9 subspecies inhabit the state, including N. f. campestris , N. f. attwateri , and N. f. baileyi . We determined distributional limits of N. f. campestris along 2 river systems in southern Nebraska. As observed with other mammalian species in the Great Plains, we suspected that the distribution of woodrats likely had expanded, reflecting continued regulation of rivers and the concomitant increase in forests along them. We documented N. f. campestris at 7 sites in 5 counties, including a recent (since the 1960s) eastward expansion along the Republican River. We observed little movement along the Platte River. The greatest concentration of houses constructed by woodrats occurred in a shelterbelt near the Republican River; otherwise, abundances of houses tended to be greater along the Platte River. We suspect that the distribution of woodrats will continue to change in Nebraska unless breaks exist or are established in riparian forests along the Platte and Republican rivers.     

Survey of Wyoming crayfishes

Collections of crayfish by Wyoming Game and Fish Department biologists and University of Wyoming staff in 1985-1987 included five species: Pacifastacus gambelii , the only species found in the Snake River and Bear River drainages of western Wyoming; Orconectes neglectus neglectus , collected from one reservoir in the South Platte River drainage in southeastern Wyoming (its first reported occurrence in the state); O. immunis and O. virilis ,widespread east of the Continental Divide and in the Green River drainage of southwestern Wyoming; and Cambarus Diogenes Diogenes , collected from a tributary of the North Platte River in eastern Wyoming.     

Ecological investigation of a suspected spawning site of Colorado squawfish on the Yampa River, Utah

On 5 July 1981, 13 adult Colorado squawfish were found in spawning condition at river mile 16.5 in the Yampa River, a major tributary to the Green River. An investigation was undertaken to quantitatively describe this section of the river to gain insights on the spawning requirements of this endangered species. The substrate at the suspected spawning site was cobble with large interstitial spaces devoid of organics, silts, or clays. It appeared that larvae of several fish species utilized these cobble areas and the associated voids. Diurnal sampling indicated that larval drift occurred between 0100 and 0125 hours. Substrate size also appeared to be a dominant factor in fish distribution. Feeding intensities of these fish corresponded to macroinvertebrate drift.         

Archaeological record of native fishes of the lower Colorado River: how to identify their remains

Archaeological sites in the Salton Basin of southeastern California and along the lower Colorado River provided opportunities to determine which fish species were present prior to extirpations, environmental degradation, and the recession of Lake Cahuilla. These remains also represent the fishes exploited by Native Americans. Bonytail ( Gila elegans ), razorback sucker ( Xyrauchen texanus ), Colorado pikeminnow ( Ptychocheilus lucius ), striped mullet ( Mugil cephalus ), and machete ( Elops affinis ) have been recovered from 117 sites in the Salton Basin, once filled by the Colorado River forming Lake Cahuilla. Bonytail and razorback sucker comprise nearly 99% of the remains. Along the lower Colorado River itself, fragmentary elements of bonytail, razorback sucker, Colorado pikeminnow, and roundtail chub ( G. robusta ) have been recovered, documenting a disappearing native fish fauna. Anatomical details are described that permit identification of diagnostic materials commonly recovered during archaeological excavations.     

Distribution and first reports of Branchiobdellida (Annelida: Clitellata) on crayfish in the prairie provinces of Canada

Orconectes virilis (northern crayfish) were collected from 67 sites in Alberta, Saskatchewan, Manitoba, and far-western Ontario, Canada, and yielded 2 species of branchiobdellidans, Cambarincola vitreus and Cambarincola chirocephalus. This is the first report of branchiobdellidans in the Prairie Provinces. Cambarincola vitreus was distributed across the study area, but C. chirocephalus appeared to be restricted to southeastern Saskatchewan, southern Manitoba, and the site in western Ontario. Neither branchiobdellidan species was observed on crayfish in the Beaver River or the South Saskatchewan River and associated tributaries upstream (west) of Saskatoon, Saskatchewan, despite multiple sampling at these locations.     

Home-range fidelity and use of historic habitat by adult Colorado pikeminnow ( Ptychocheilus lucius ) in the White River, Colorado and Utah

Twelve wild adult Colorado pikeminnow ( Ptychocheilus lucius ), captured in the tailwaters of Taylor Draw Dam on the White River, Colorado, were implanted with radio transmitters and their movement patterns monitored from 1992 to 1994. The spawning migration of these fish was extensive. In 1993, the only full year of the study, the fish migrated an average of 658 km from the White River to spawning sites in the Yampa or Green rivers and back to the White River. Eight of these fish were translocated in the river upstream of the dam in April 1993. These fish and the 4 others below the dam remained in the river until May 1993. All 12 had migrated down the White River to spawning sites in the Green and Yampa rivers by July 1993. The fish that were located above the dam successfully passed over the dam during their downstream migration. Seven fish migrated upstream toward the Yampa River Canyon spawning site and 5 migrated downstream toward the Green River Desolation/Gray Canyon spawning site. Five of 7 Yampa River fish were found at the spawning site. The other 2 were found 5-8 km downstream of the site. One of 5 Green River fish was found at the spawning site, the other 4 between 16 and 62 km upstream of the site. All fish migrated back to the White River by August 1993 and were found near the dam by October 1993. Two fish were recaptured and translocated above the dam in September 1993. Five fish were located below the dam and 2 above the dam in April 1994. By July 1994 seven of the same fish that had migrated toward the Yampa River in 1993 were found at the Yampa Canyon spawning site. At the same time, 3 of 5 fish that migrated toward the Green River in 1993 were found at the Desolation/Gray Canyon spawning site. This included 2 fish that had been found upstream of the site in 1993. The 12 fish traveled an average of 6 km d -1 (range: 4-10 km d -1 ) during the migration period from May through October 1993. Generally, fish moved faster to the spawning site than back from the site to the White River. These fish moved very little within their home ranges in the White River. Six fish tagged in 1992 moved only 0.1-2.3 km in the tailwater reach below Taylor Draw Dam from September 1992 through April 1993. All fish, after their spawning runs, had moved up to or near the dam by October 1993. These fish were not tracked again until April 1994. Their movement patterns in April 1994 were similar to those observed in April 1993. The greatest amount of fish movement in the White River was displayed by the 8 fish placed above Taylor Draw Dam in April 1993 and the 2 placed in Kenney Reservoir in September 1993. They moved 1.1-40.6 km in the river before and after their spawning migration in spring and autumn 1993. These spawning migrations suggest that adult Colorado pikeminnow in the White River were recruited from both Green and Yampa river spawning populations and were presumably imprinted to these respective spawning sites. Those fish placed above Taylor Draw Dam established home ranges in habitats previously occupied by Colorado pikeminnow before the dam was completed. They remained there until they migrated downstream during the spawning period. Although we did not study fish passage, our study demonstrates that adult Colorado pikeminnow will use habitat if access is provided. Translocation of wild adult fish into historic but unoccupied habitats may be a valuable recovery option.     

Food and habitat relationships of Claassenia sabulosa (Plecoptera: Perlidae) in the Upper Colorado River, Colorado

Streambed surveys were conducted along the upper Colorado River, Colorado, to describe the distributions of Claassenia sabulosa larvae in relation to current speed and to determine their diets. We also addressed diel feeding periodicity by sampling during both day and night. Claassenia sabulosa was more abundant in riffle habitats than in runs. A positive relationship existed between C. sabulosa abundance and stream current, with larval size increasing with current speed. Chironomidae, Baetidae, and Simulidae collectively accounted for 93% of the prey found in stonefly guts; however, these categories were not consumed equally by all C. sabulosa . Smaller C. sabulosa primarily ate chironomids, and larger individuals consumed more baetids. Only a slight difference existed in the percentage of empty guts between night- and day-collected stoneflies, and ranges of prey per gut at night were higher than those in the day, suggesting that these stoneflies may forage more intensively at night.     

Inter-simple sequence repeat (ISSR) variation in three populations of Gaura neomexicana ssp. coloradensis (Onagraceae), F.E. Warren Air Force Base, Cheyenne, Wyoming

We investigated genetic variation within and between 3 populations of Gaura neomexicana ssp. coloradensis , a federally listed threatened species, using inter-simple sequence repeats. The data matrix included 24 individuals scored for 88 bands, with 3.4% missing data. Cluster analysis showed that members of the 3 populations are very similar and are intermixed in the phenogram. Principal coordinate analysis indicated that members of the Crow Creek population are different from the Diamond Creek and ""unnamed drainage"" populations. This could be the result of historic differences, current changes in vegetation at the Crow Creek site, or an artifact of limited sampling. In any case, for management purposes it is best to preserve the dwindling population at Crow Creek as well as the thriving populations at the other 2 sites.     

Caddisfly (Trichoptera) assemblages along major river drainages in Arizona

Seventy-two caddisfly species in 36 genera and 15 families were collected along the Little Colorado, Verde, Gila, and Colorado rivers in Arizona. Brachycentrids, hydropsychids, limnephilids, and uenoids made up nearly 50% of the assemblage in forested sites above 2200 m. Hydropsychids, hydroptilids, and leptocerids made up 75% of the assemblage in grassland watersheds between 2200 and 1000 m, and 80% at sites below 1000 m in desert watersheds. Species richness averaged 16 at sites above 2200 m elevation, 7 between 2200 and 1000 m, and 3 below 1000 m. H' diversity was typically >3 at sites above 2200 m and <2.5 below 2200 m. Each river had distinct faunas likely due to isolation of drainages across semiarid landscapes. Low S&oslash;rensen similarity values were measured for caddisfly assemblages in the highly regulated Colorado River and the other 3 rivers. Only 17 species were collected at 14 sites along 700 km of the Colorado River. Indicator caddisfly species are provided for altered and less disturbed drainages. We added 7 species not previously reported in Arizona for a total of 154 caddisfly species in the state. We provide a baseline of caddisfly indicators for monitoring changes in ecosystem health during the predicted long-term drought and population expansion in southwestern USA.     

Electrophoretic study of cutthroat trout populations in Utah

Thirty - nine Utah streams were sampled for cutthroat trout. Of these, 31 contain cutthroat or cutthroat / rainbow hybrid populations. By using starch gel electrophoresis, these populations were segregated into three groups. One group consisted predominately of fish from the Sevier River (of the Bonneville Basin) and Colorado drainages. A second was primarily populations from the Bear River Drainage (Bonneville Basin) as well as some scattered populations along the Wasatch Front (Bonneville Basin). The third consisted of Wasatch Front populations and populations that have hybridized with rainbow trout. Since different subspecies of cutthroat trout are native to the Colorado and Bonneville drainages, one would expect the populations from within the Bonneville Basin to be more similar to one another and less similar to the Colorado River populations. That this did not occur raises questions concerning the evolutionary relationships of the subspecies and the populations. It is clear that at least a northern (Bear River) and southern (Sevier River) form of the Bonneville cutthroat exists. The Wasatch Front may represent an intermediate zone where these two forms intergrade. &nbsp;&nbsp;&nbsp;     

Ophiotaenia critica (Cestoda: Proteocephalidae), a parasite of the Colorado River squawfish

A total of 19 cestodes, Ophiotaenia sp., were recovered by deworming from adult Colorado River Squawfish ( Pteichocheilius licius ) maintained at the U.S. National Fish Hatchery at Willow Beach, Arizona. These specimens differ from other described species and are named Ophiotaenia critica.     

Small mammals within riparian habitats of a regulated and unregulated arid land river

In northwestern Colorado, flow regulation on the Green River has created a transitional plant community that features encroachment by upland vegetation into cottonwood ( Populus fremontii )-dominated, riparian forest on topographically high floodplain sites and reduced cottonwood regeneration on low floodplain sites. To assess how these changes might have affected small mammal distributions, in 1994 and 1995 we live-trapped during periods surrounding spring flooding at 3 sites: above and below the confluence of the regulated Green River and at the ecologically similar, but unregulated, Yampa River (reference site). More species were captured at the most regulated site along the Green River above its confluence with the Yampa River. Within sites, more species were captured in riparian habitats than adjacent upland habitats. Despite river regulation-induced habitat changes, we did not detect changes in species distributions within low and high floodplain habitat for Peromyscus maniculatus or Microtus montanus , but changes may have occurred for Dipodomys ordii . The total effect of regulation-induced habitat change on small mammal populations may not be fully revealed until current, mature cottonwood forests disappear and associated woody debris decomposes.     

Diatom species composition and ecology of the Animas River Watershed, Colorado, USA

The diatom flora of selected sites in the Animas River Watershed, San Juan County, Colorado, was studied. Eighty diatom taxa were identified from 10 sites: 8 sites on the Animas River and 1 site each on the Cement and Cascade tributaries. The sample diatom abundance was dominated by Achnanthidium minutissimum , Encyonema silesiacum , Aulacoseira distans , Hannaea arcus , and Diatoma mesodon . The presence of teratologic specimens of Fragilaria and Achnanthidium in the samples indicated the possibility of metals contamination. Diatom diversity was low and Lange-Bertalot pollution index scores indicated little organic pollution evidenced from diatom composition. There was evidence that diatom composition at the sites was differentially affected by pH and possibly by the concentrations of Zn alone or in combination with Cd, Cu, and Fe.     

New amphipods of hydrothermal vent environments on the Mid‐Atlantic Ridge,Azores Triple junction zone

This work is the third publication on the new amphipod species collected from the Azores Triple junction zone by the cruises ATOS, DIVA 2, MARVEL, PICO and SEAHMA 1. Seven new species and a new genus are described belonging to six families, Eusiridae, Leucothoidae, Oedicerotidae, Phoxocephalidae, Pleustidae, and Podoceridae. They were sampled in four sites, Menez Gwen, Lucky Strike, Saldanha and Rainbow.     

Roost sites used by Sandhill Crane staging along the Platte River, Nebraska

We assessed the influence of water depth, extent of unobstructed view, and human disturbance features on use of roost sites by Sandhill Cranes along the Platte River, Nebraska, during spring migratory stopover. Aerial photos taken near dawn were used to determine areas of flock use and habitat availability in four sample reaches, and measurements were made on the ground at flock roost areas. In general, depths of 1-13 cm were used by sandhill cranes in greater proportion than those available. Exposed sandbars and depths >20 cm were avoided, while depths of 14-19 cm were used in proportion to their availability. Sites 11-50 m from the nearest visual obstruction were used significantly greater than their availability, while sites 0-4 and >50 m from visual obstructions were avoided. Sandhill Cranes avoided sites near paved roads, gravel roads, single dwellings, and bridges when selecting roost sites; however, they did not appear to be disturbed by private roads, groups of residential buildings, gravel pits, railroads, or electrical transmission lines.     

Changes in riparian vegetation along the Colorado River and Rio Grande, Colorado

Changes in vegetation including area occupied, canopy cover, and maturity class of cottonwoods ( Populus spp.) within lower-elevation zones of the Colorado River and Rio Grande in Colorado were monitored over 25- and 27-year intervals, respectively, using photo-interpretative methods. Estimated loss of cottonwoods along the Colorado River was 2ha/km (-17.5%), and remaining stands had become more open and older. Cottonwoods along the Rio Grande increased 1.6 ha/km (9.3%) with minor canopy cover and maturity class changes. Area occupied by shrubs and river channel changed little along the Colorado River, but declined along the Rio Grande. Loss of hay meadow occurred along both rivers, whereas developed land increased along the Colorado River and farmland increased along the Rio Grande. Wildlife habitats along the Colorado deteriorated much more rapidly than those along the Rio Grande during monitored intervals.     

Transverse and longitudinal variation in woody riparian vegetation along a montane river

This study explores how the relationship between flow and riparian vegetation varies along a montane river. We mapped occurrence of woody riparian plant communities along 58 km of the San Miguel River in southwestern Colorado. We determined the recurrence interval of inundation for each plant community by combining step-backwater hydraulic modeling at 4 representative reaches with Log-Pearson analysis of 4 stream gaging stations. Finally, we mapped bottomland surficial geology and used a Geographic Information System to overlay the coverages of geology and vegetation. Plant communities were distinctly arrayed along the hydrologic gradient. The Salix exigua Nuttall (sandbar willow) community occurred mostly on surfaces with a recurrence interval of inundation shorter than 2.2 years; the Betula occidentalis Hooker (river birch) community peaked on sites with recurrence intervals of inundation between 2.2 and 4.6 years. The hydrologic position occupied by communities dominated by Populus angustifolia James (narrowleaf cottonwood) was strongly related to age of trees and species composition of understory shrubs. The fraction of riparian vegetation on surfaces historically inundated by the river decreased in the upstream direction from almost 100% near Uravan to <50% along the South Fork of the San Miguel River. In upstream reaches much of the physical disturbance necessary to maintain riparian vegetation is provided by valley-side processes including debris flows, floods from minor tributaries, landslides, and beaver activity. Where valley-side processes are important, prediction of riparian vegetation change based on alterations of river flow will be incomplete.     

The effect of elevation on the distribution of sibling species in the Simulium arcticum complex (Diptera: Simuliidae)

At least 5 sibling species and an additional 11 cytotypes of the Simulium arcticum complex occur in Montana. Consequently, this speciose complex might allow study of environmental correlates with genetic differentiation. We used conventional methods of collection and cytogenetic analysis to study 1128 male larvae of the Simulium arcticum complex at 15 sites within 5 drainages in western Montana to test the hypothesis that distribution of siblings is associated with elevation. We sampled at the mouth, at the headwaters, and at an intermediate site to span the range of elevations within each drainage. We restricted our analyses to the most abundant taxa of the S. arcticum complex within our study area and observed a statistically significant presence of S. apricarium at low-elevation sites. Simulium arcticum IIL-18 appeared more frequently than expected at high elevation sites. Simulium brevicercum and S. arcticum sensu strictu appeared to be distributed randomly. We suggest potential causal reasons for these distributions including differential use of habitats along these elevational gradients.     

Small-stone content of Mima mounds of the Columbia Plateau and Rocky Mountain regions: implications for mound origin

Mima moundfields were investigated at the Lawrence Memorial Grassland Preserve, located on the Columbia Plateau in southern Wasco County, Oregon, and at three locations in the San Luis Valley and Sangre de Cristo Mountains, southern Colorado, to test the alternative hypotheses of mound origins by erosion, frost action, and soil translocation by geomyid pocket gophers. The concentrations of two size classes of small stones, gravel (8-15 mm diameter) and pebbles (15-50 mm diameter), were sampled along mound-to-intermound transects and at different depths within the mounds. Numbers and masses of small stones per unit soil volume increased from intermounds to mounds tops at the Colorado sites and from mound edge to mound top at the Oregon site, where thin intermound soils lay directly on the weathering surface of basalt bedrock. Numbers and masses of small stones in the surface soil of mound tops were greater than or similar to concentrations in deeper layers. Mean masses of individual pebbles were greater in the intermound zone than in mound soils at the Oregon site, but did not differ along mound-intermound gradient at the Oregon site and at one Colorado site, being highest at mound edges or in intermounds. These observations support the hypothesis that mounds are formed by centripetal translocation of soil by geomyid pocket gophers, and are contrary to predictions based on theories assuming erosion or frost action to be the mechanism of mound formation.     

On the Distribution of Utah's Hanging Gardens

This is a summary monograph of the hanging gardens as they occur in the Colorado River and Virgin River portion of the Colorado Plateau in Utah. Discussed in this paper are the hanging gardens, their geography, geomorphology, aspects of distribution and diversity, and principal vascular and algal plant species. Animal trapping studies and pland productivity aspects are reviewed.