First Pleistocene jumping mouse ( Zapus , Zapodinae, Rodentia) from Utah

Two of the Little Dell Dam fossil localities produced the 1st Pleistocene records of the jumping mouse Zapus from Utah. We describe these teeth in detail and compare their morphology with both extinct and extant jumping mouse taxa. Although it is not possible to confidently assign these specimens to a particular species, the Little Dell Dam fossils are clearly distinct from the only living jumping mouse ( Zapus princeps ) currently known from Utah. The paracone is attached to the rest of the occlusal surface of the upper 1st and 2nd molars in modern Z. princeps from Utah; the paracone is isolated in the molars from Little Dell Dam. The fossils from Little Dell Dam are the 1st reported records of Pleistocene Zapus west of the Rocky Mountains.     

Deer mouse, Peromyscus maniculatus, and associated rodent fleas (Siphonaptera) in the arctic-alpine life zone of Rocky Mountain National Park, Colorado

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Peromyscus maniculatus and related small rodents have been examined for ectoparasites in the tundra region of the Rocky Mountain National Park 1974–1979. One hundred and ninety-four P. maniculatus were examined from two tundra sites. Flea infestation rates were 1.9 fleas per mouse examined and 4.1 fleas per infested mouse. Species taken in significant numbers were Monopsyllus thambus (51 percent), Peromyscopsylla hesperomys (34 percent), Malaraeus euphorbi (9 percent), and Catallagia calisheri (4 percent). Peromyscus maniculatus host/flea relationships in the tundra are compared with those in other life zones in the park.       

Denning chronology of black bears in eastern Rocky Mountain National Park, Colorado

Understanding factors influencing the timing of den entrance and emergence of black bears ( Ursus americanus ) provides insight for bear management. We determined den entrance and emergence dates for bears in Rocky Mountain National Park (RMNP) and related these dates to vegetative productivity, weather, habitat, and demographic factors to assess the influence of these factors on denning chronology. Date of den entrance was most strongly influenced by age class, precipitation, and proportion of human-use areas in annual home ranges. Den entrance was typically later for adult bears during wetter years and when annual home ranges contained a greater proportion of human-use areas. Sex and presence of human-use areas were most strongly related to den emergence. Male bears typically emerged from dens before females, and bears emerged from dens earlier when human-use areas composed a greater proportion of annual home ranges. Collectively, our results suggest that denning behavior of black bears in RMNP was strongly influenced by presence of human-use areas, likely because of foods associated with such areas. Managers of black bears in RMNP can use precipitation to predict relative dates of den entrance, thereby allowing for more efficient strategies to combat potentially negative human–black bear encounters.     

Alpine vascular flora of the Ruby Range, West Elk Mountains, Colorado

The Ruby Range is a northern extension of the West Elk Mountains of west central Colorado. Composed primarily of sedimentary rocks, the range is heavily faulted and intruded by many dikes and sills. Eight study areas, selected as representative of the major topographic features of the range, were analyzed floristically. A vascular flora of 220 species in 111 genera and 35 families is reported. The phytogeographic distribution of the flora is primarily alpine and western North American. The flora of the Ruby Range shows a 74% similarity to the flora of the San Juan Mountains to the southwest.     

Transverse pattern of vegetation on avalanche paths in the northern Rocky Mountains, Montana

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The pattern of vegetation on avalanche paths has usually been ascribed to the damage done by snowslides. In the northern Rocky Mountains the pattern of herbs, shrubs, and small trees appears to be more complex than could be accounted for by avalanche magnitude and frequency. The vegetation on one path in Montana illustrates that the topography of the path is a factor in the distribution of species. Three zones exist across avalanche paths: an inner zone of herbs and suffrutescent shrubs occupying a ravine, which is snow covered longer than elsewhere; flanking zones of dense shrubs and trees with flexible stems; and an outer zone of less dense shrubs that is more xeric. The pattern of vegetation seems to be due to avalanche-related stress rather than damage.        

Tundra vegetation of three cirque basins in the northern San Juan Mountains, Colorado

The vegetation of three alpine cirque basins in the northern San Juan Mountains of southwestern Colorado was inventoried and analyzed for the degree of specificity shown by vascular plant communities for certain types of habitats identified as representative of the basins. A total of 197 vascular plant species representing 31 families was inventoried. Growth forms of all species were noted and a growth form spectrum for all of the communities was derived. The caespitose monocot and erect dicot growth forms are the most important growth forms among the community dominants. The most common growth form among all species is the rosette dicot.           

Natural variability of vegetation, soils, and physiography in the bristlecone pine forest of the Rocky Mountains

Pinus aristata Engelm. forest vegetation in Colorado was studied to determine vegetation composition and the relationship between vegetation and environment. Species percent cover, tree size class, and environmental variables were recorded for 49 plots. Previously collected data for 4 plots form New Mexico were included. Environmental variables included latitude, longitude, elevation, slope, aspect, topographic position, parent material, percent rock cover, mean rock size, litter depth, estimated plot age class, and evidence of anthropogenic disturbance. Soils were analyzed for texture, depth, and percent carbon and nitrogen. Pinus aristata foliage was analyzed for percent nitrogen and phosphorus. Direct and indirect gradient analyses (CANOCO) were used to determine environmental factors associated with community composition. Vegetation in P. aristata forests is influenced primarily by elevation and soil pH. Substrate, soil texture, topographic position, and geographic location are secondary factors. Six plant associations were identified using cluster analysis (listed in an elevational sequence from low to high): Pinus aristata/ Festuca arizonica Vasey, Pinus aristata / Festuca thurberi Vasey, Pinus aristata / Juniperus communis L., Pinus aristata / Vaccinium myrtilus L., Pinus aristata / Ribes montigenum McClatchie, and Pinus aristata / Trifolium dasyphyllum Torr. & Gray.     

A classification of aquatic plant communities within the Nothern Rocky Mountains

A synecological study of aquatic macrophyte plant communities was conducted across northern Idaho and western Montana during the summers of 1997, 1998, and 1999. A total of 111 natural and man-made water bodies were sampled based on a stratification of environmental variables thought to influence plant species distribution (i.e., elevation, landform, geology, and water body size). Plant species foliar cover data were used to develop a hierarchical, floristic-based community type classification with TWINSPAN and DECORANA software. Six planmergent (conspicuous portion of vegetative plant body on the water surface) and 24 submergent (vegetative plant body found primarily underwater) community types were identified. Multivariate analysis indicated that all community types displayed significant differences in plant species composition, and the Sorensons floristic similarity between communities averaged 10% for planmergent and 8% for submergent types. Canonical correspondence analysis was used to inspect relationships between abiotic factors and plant species abundance. Results of this analysis indicated some relationships between species distributions and abiotic factors; however, chance introduction of plant species to water bodies is a process considered to be equally important to the presence of the community types described.     

Use of nonalpine anthropogenic habitats by American pikas ( Ochotona princeps ) in western Oregon

The American pika ( Ochotona princeps Richardson) has long been characterized in field guides and popular literature as an obligate inhabitant of alpine talus and as having relatively low dispersal capability. However, recent work reveals pikas to have broader habitat associations than previously reported. Over a large portion of the western slope of the Cascade Range in Oregon, pikas inhabit relatively low-elevation sites far from alpine areas and frequently occur in rocky man-made habitats such as roadcuts or rock quarries. We present observations of pikas in these previously overlooked habitats and discuss implications for (1) the proposed listing of the American pika as an endangered or threatened species; (2) furthering our understanding of pika population dynamics, habitat associations, and dispersal capabilites; and (3) management of federal, state, and private forest lands. Por mucho tiempo la pika americana ( Ochotona princeps Richardson) ha sido caracterizada en guías de campo y literatura popular como un habitante obligado de taludes alpinos y por tener una capacidad de dispersión relativamente baja. Sin embargo, trabajo reciente ha revelado que las pikas tienen asociaciones de hábitat más amplias de lo que hasta ahora se creía. En una gran parte de la vertiente occidental de la cordillera Cascade en Oregón, las pikas habitan sitios de elevación relativamente baja, lejos de las áreas alpinas y frecuentemente aparecen en hábitats rocosos artificiales tales como canteras y cortes de carretera. Presentamos observaciones de pikas en estos hábitats pasados por alto anteriormente y discutimos las implicaciones para (1) la propuesta de agregar la pika americana a la lista de especies amenazadas o en peligro; (2) ampliar nuestro conocimiento sobre la dinámica poblacional, las asociaciones de hábitat y la capacidad de dispersión; y (3) la gestión de tierras forestales federales, estatales y privadas.     

Ungulate herbivory on alpine willow in the Sangre de Cristo Mountains of Colorado

In many areas of the Rocky Mountains, elk ( Cervus elaphus ) migrate from low-elevation mountain valleys during spring to high-elevation subalpine and alpine areas for the summer. Research has focused on the impacts of elk herbivory on winter-range plant communities, particularly on woody species such as willow and aspen; however, little information is available on the effects of elk herbivory on alpine willows. In the Sangre de Cristo Mountains of south central Colorado, select alpine areas appear to receive high levels of summer elk herbivory, while other areas are nearly unbrowsed. In 2005 and 2008, we measured willow height, cover, and utilization on sites that appeared to be used heavily by elk, as well as on sites that appeared to be used lightly, to determine differences between these communities over time. We found less willow cover and shorter willows at sites that received higher levels of browsing compared to those that had lower levels of browsing. Human recreational use was greater at lightly browsed sites than at highly browsed sites. From 2005 to 2008, willow utilization declined, and willow cover and height increased at sites with heavy browsing, likely owing to ownership change of adjacent valley land which led to (1) removal of grazing competition from cattle at valley locations and (2) increased human use in alpine areas, which displaced elk. We discuss the implications of increased human use and climate change on elk use of these alpine habitats. En muchas áreas de las Montañas Rocosas, el ciervo rojo ( Cervus elaphus ) migra durante la primavera de valles montañosos de baja elevación a áreas altas subalpinas y alpinas para el verano. Hasta ahora la investigación se ha enfocado en el impacto de la herbivoría del ciervo rojo sobre las comunidades de plantas en el invierno, particularmente en las especies leñosas como el sauce y el álamo; sin embargo, existe poca información disponible sobre el efecto de la herbivoría del ciervo rojo en los sauces alpinos. En la cordillera Sangre de Cristo al centro-sur de Colorado, ciertas áreas alpinas parecen tener altos niveles de herbivoría de verano por el ciervo rojo, en tanto que otras áreas quedan casi sin ramoneo. En 2005 y 2008 medimos la altura, cobertura y uso de los sauces en sitios en los que parecía haber sido abundante el ramoneo y los comparamos con sitios donde parecía haber sido más ligero, a fin de determinar las diferencias entre estas comunidades en el tiempo. Encontramos menos cobertura y altura de sauces en los sitios que recibían niveles más altos de ramoneo en comparación a los que tenían menos evidencia de ello. El uso humano recreativo era mayor en los sitios de ramoneo ligero que en donde era abundante. De 2005 a 2008, disminuyó el uso y aumentó la cobertura y la altura en sitios de ramoneo abundante, probablemente debido a que un valle adyacente cambió de propietario, lo cual provocó (1) la eliminación de la competencia por el pastoreo en ganado en el valle; y (2) un aumento del uso humano en áreas alpinas, desplazando al ciervo rojo. Discutimos las implicaciones del aumento del uso humano y el cambio climático en el uso por el ciervo rojo de estos hábitats alpinos.     

Comparative successional roles of trembling aspen and lodgepole pine in the Southern Rocky Mountains

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} A review of the ecological distribution and successional roles of lodgepole pine and trembling aspen in the Southern Rocky Mountains suggests that the two species have different strategies for occupying disturbed sites. Lodgepole pine’s easily dispersed seeds and faster growth from seed in unsuppressed conditions allows it to colonize severe burns, even from remote seed sources. Aspen appears to compensate for ineffective development from seed by vegetative reproduction from durable root stocks, which promotes geographic persistence. Such persistence is achieved by the maintenance of a forest structure conducive to light surface fires, which stimulate suckering and retard conifer invasion, and by the accumulation of soil organic matter, which improves site nutrient retention and water availability.       

Classification of the riparian vegetation of the montane and subalpine zones in western Colorado

A classification of the riparian vegetation of part of western Colorado was developed by cluster analysis and ordination of 115 samples of relatively undisturbed vegetation. The classification of plant associations contains five montane riparian forests, three subalpine riparian forests, four lower subalpine willow carrs, three upper subalpine willow carrs, and one subalpine wetland.     

New records and range extensions of species of Dipogon (Hymenoptera, Pompilidae) in Colorado

Four species of Dipogon are recorded from Colorado for the first time. These are hurdi Evans, pulchripennis (Cresson), graenicheri Banks, and brevis (Cresson). All are inhabitants of wooded areas and are believed to nest in cavities in trees. Notes are presented on habitat and prey of these 4 species and of the recently described species kiowa Evans.     

New species of oribatids from western Colorado (Acarina: Cryptostigmata, Suctobelbidae)

A new species of Suctobelba, S. tumulata, and a new genus and species, Parisuctobelba septenia, are described from collections of oribatids taken in coal strip-mining spoil banks near Hayden, Colorado. The new species are compared with members of the family from North America and Europe. The new genus is differentiated by a smooth, narrowed sensillum and seven pairs of genital setae. Taxonomic and ecological data are also discussed.     

Impacts of nonnative plant species on production and diversity in the front range of Colorado

Nonnative plant species are considered one of the greatest threats to biodiversity, yet we still are unable to predict how production and diversity of a community will change once a species has invaded. Ponderosa pine woodlands in the Front Range of Colorado are ideal for studying the impacts of nonnative plants on production and species richness. We selected 5 sites along the northern Front Range with varying proportions of nonnative and native species and compared understory production and species richness along the gradient of nonnative species dominance. Total species production was positively and significantly related to total species richness, and total species production increased significantly with increasing nonnative species richness. There was a negative relationship between native and nonnative species production, and there was no relationship between nonnative species richness and native species richness. This study demonstrates the complex nature of species richness and productivity relationships and should serve as a starting point for future research in which a variety of other variables are considered.     

Growth and development of the western harvest mouse, Reithrodontomys megalotis megalotis

Growth rates, gestation period, litter size, reproductive age, sex ratios, and development were studied on 198 litters of Reithrodontomys megalotis megalotis (Baird). Growth was characterized by several standard skull and body measurements and was partitioned into four phases of 1 – 3, 4 – 12, 13 – 22, and 23 – 70 days. Growth was best described by measurements of tail length, ear length, and dried eye - lens weight. Reproductive activity began as early as 38 days for females and 59 days for males. The gestation period was 22 days, and the mean litter size was 3.83 (range 1 – 7). Sex ratio was 53.49 percent males to 46.51 percent females. Reproductive efficiency was 53.53 percent. The development of R. m. megalotis was very similar to that of R. m. dychei. Early breeding, postpartum estrous, year - round breeding, high reproductive efficiency, and a short gestation period contribute to a high reproductive potential in R. m. megalotis.       

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.