Habitat and distribution of pygmy rabbits ( Sylvilagus idahoensis ) in Oregon

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;} An investigation to determine the location and extent of populations of pygmy rabbits ( Sylvilagus idahoensis ) in Oregon, and to describe several biotic and physical components within communities that include pygmy rabbits, was conducted from October 1981 to September 1983. Of 211 sites suspected of supporting the species based on interpretation of museum records, aerial photographs, soil maps, and interviews with biologists and area residents, 51 exhibited evidence of being inhabited when examined in summer 1982. Soil and vegetation components were sampled at 15 sites occupied by pygmy rabbits and 21 sites adjacent thereto. At inhabited sites, mean soil depth (51.0 ± 2.3 cm), mean soil strength of surface (0.8 ± 0.2 kg/cm 2 ) and subsurface (3.8 ± 0.3 kg/cm 2 ) horizons, shrub height (84.4 ± 5.8 cm), and shrub cover (28.8 ± 1.4%) were significantly greater ( P 2 ), density of forbs (3.4 ± 0.6/1,000 cm 2 ), and cryptogam cover (2.4 ± 0.5%) were not. Except for the clay component of subsurface soils, texture of surface and subsurface soils were not significantly different between sites occupied by pygmy rabbits and adjacent sites. The affinity of pygmy rabbits for areas with greater shrub cover, shrub height, soil strength, and soil depth, and, to a small degree, coarser soil texture possibly was related to availability of forage, security from predation, and ease of burrow construction. Analysis of 472 samples of sagebrush ( Artemisia tridentata ) collected at and near sites inhabited by pygmy rabbits indicated their distribution was not dependent upon the presence of specific subspecies of sagebrush. A marked decrese in evidence of occupancy of sample sites and of pygmy rabbit activity at occupied sites in 1983 indicated that populations of pygmy rabbits were susceptible to rapid declines and possible local extirpation. Fragmentation of sagebrush communities poses a potential threat to populations of pygmy rabbits, but the severity of the threat presently is unknown.     

Daily and seasonal patterns of activity at pygmy rabbit burrows in Utah

The pygmy rabbit ( Brachylagus idahoensis ) is a secretive, obligate sagebrush-steppe resident of the Intermountain West and is one of two rabbits in North America that digs its own burrows. Although the pygmy rabbit has a recorded home range of 0.21–67.9 ha in relatively high sagebrush cover (21%–36%), they spend much of their time within 30–100 m of a burrow system. Due to big sagebrush cover in preferred habitat and the secretive behavior of pygmy rabbits, it is often difficult to study this leporid through direct observation. We used remote cameras to document pygmy rabbit activity at burrow systems in south central Utah from 2006 to 2008. We analyzed photographs from remote cameras for daily and seasonal patterns of activity. Our results suggested that time of day and season were important influences on activity level, while year and site were less so. Pygmy rabbits were active during all time periods of the day, but the greatest activity occurred in the morning, except during winter. Numerous other species were recorded by remote cameras, including other leporids, birds, rodents, reptiles, and terrestrial predators. Remote cameras are a valuable tool in understanding pygmy rabbit behavior, in addition to confirming rabbit presence in areas of interest.     

Cedar Hollow, an early Holocene faunal site From Whidbey Island, Washington

Coastal erosion at central Whidbey Island reveals a cross-section view of dune sands that contain the only known record of animals that inhabited the Pacific Northwest coast during the early Holocene. Mammal fossils include bones and teeth of deer, wolf, brown bear, and several species of rodents. A deer vertebra from basal beds yielded a 14 C age of 8840 ± 50 yr BP. The faunal diversity suggests that the region was repopulated relatively quickly following the final retreat of the Cordilleran sheet. This paleofauna was quite different from that of the late Pleistocene, when the region was inhabited by mammoth, musk oxen, giant sloth, and other large mammals. Avian remains include hawks, geese, and seabirds, 3 groups that occupied quite different ecological niches. Early Holocene bird fossils from Whidbey Island are dissimilar to late Pleistocene avifaunas from inland sites in California and Oregon, evidence that the coastal environment offered habitat conditions quite unlike those of interior wetlands.     

A habitat suitability model for pygmy rabbits ( Brachylagus iIdahoensis ) in southeastern Idaho

A habitat suitability model was developed for pygmy rabbit ( Brachylagus idahoensis ) habitat on the Idaho National Engineering and Environmental Laboratory (INEEL) in southeastern Idaho. Suitable pygmy rabbit areas were characterized by greater cover and density of total shrubs and big sagebrush ( Artemisia tridentata ), as well as greater forb cover. Soil texture also played an important role in distinguishing suitable pygmy rabbit areas from nonuse sites. Principal components analysis (PCA) of several vegetation variables and soil texture was used to develop a habitat suitability model for pygmy rabbit habitat. This model, which can be used to successfully distinguish between pygmy rabbit use and nonuse areas on the INEEL, has the potential for use throughout the pygmy rabbits range.     

Taxonomy and variation of the Lopidea nigridia complex of western North America (Heteroptera: Miridae, Orthotylinae)

External morphological variation in the Lopidea nigridia "complex" of western North America was examined using principal component analysis and showed continuous variation among populations in most characters. External morphology did not parallel paramere structure and did not substantiate previously recognized species. There was little correlation between dorsal coloration and paramere structure. Cluster analysis (UPGMA) using paramere and color characters failed to group populations coded as the same species and also failed to group all specimens of any one population. The variation in structure of the parameres and vesicae among populations of the nigridia complex was no greater than the interpopulational variation of these structures structures in the congeneric species marginata Uhler. Lopidea nigridia Uhler is treated as a polytypic species comprising three subspecies: Lopidea nigridia nigridia Uhler, a fuscous-white form from the sagebrush steppe of the Great Basin and the chaparral of southern California; Lopidea nigridia serica Knight, a solid red form from the eastern slopes of the Rocky Mountains from Alberta to Colorado and east across the Northern Great Plains to southern Manitoba; Lopidea nigridia aculeata Van Duzee, a polymorphic form varying from solid red to fuscous red and white from the Cascade Mountains and eastern slopes of the coastal ranges of British Columbia, Washington, and Oregon, the Blue and Wallawa mountains of Oregon and Washington, and throughout the Coastal and Sierra Nevada ranges of California. The following new synonymies are created: Lopidea nigridia Uhler -- Lopidea raineri Knight, Lopidea scullent Knight, Lopidea rolfsi Knight, and Lopidea wilcoxi Knight; Lopidea nigridia aculeata Van Duzee -- Lopidea nigridia hirta Van Duzee, Lopidea usingeri Van Duzee, Lopidea discreta Van Duzee, Lopidea fallax Knight, Lopidea Yakima Knight, Lopidea audeni Knight, Lopidea eriogoni Knight, Lopidea calcaria Knight, Lopidea chamberlini Knight, Lopidea angustata Knight, Lopidea rubrofusca Knight, and Lopidea flavicostata Knight and Schaffner; Lopidea nigridia serica Knight -- Lopidea medleri Akingbohungbe.     

Autumn and winter food habits of bobcats in Washington state

The stomach contents were examined from 324 western Washington bobcats ( Felis rufus ) and 123 from eastern Washington taken by hunters from 1976 through 1980, for major prey items as well as sex- and age-related differences in diet. Western Washington bobcats ate primarily mountain beavers ( Aplodontia rufa ) (42% occurrence) and snowshoe hares ( Lepus americanus ) (26%). Within that population females ate larger quantities of smaller prey such as douglas squirrels ( Tamiasciurus douglasi ) and lesser amounts of deer ( Odocoileus sp.) than males. Bobcat diets in eastern Washington were more diverse; main foods consisted of lagomorphs ( Sylvilagus nuttallii, Lepus sp.) (20%), red squirrels ( Tamiasciurus hudsonicus ) (15%), deer (11%), and voles ( Microtus sp.) (11%). Age-related differences were most prevalent in this population, with adults consuming larger quantities of deer and larger prey than did kittens.     

Survey indicators for pygmy rabbits: temporal trends of burrow systems and pellets

Obtaining estimates of absolute abundance for rare or cryptic species can be challenging. In these cases,methods using indirect indicators such as sign might offer useful indices of population size. Pygmy rabbits ( Brachylagus idahoensis ) are small, burrowing lagomorphs for which methods for population assessment and monitoring are needed. Current tools for estimating relative abundance rely on detecting and assessing fecal pellets and burrow systems. We evaluated temporal changes in each of these indicators to gauge their potential usefulness as indicators of relative and absolute abundance of pygmy rabbits. Pellet persistence was strongly influenced by environmental exposure, and based on our data, we estimated that maximum persistence of fecal pellets would be 24–34 months. Pellet appearance (color) was affected by both time and exposure. Burrow systems were remarkably resilient over the course of the study. Probability of burrow systems transitioning between activity classes (active, recent, and old) did not vary detectably by study site, season, or year. We suggest that 2 protocols currently used for classification of pygmy rabbit burrow systems are most useful for different applications. Further work is needed, however, to link such assessments to quantitative estimates of population size.     

Diets of sympatric red foxes and coyotes in southeastern Idaho

Scats of sympatric red foxes and coyotes from the upper Snake River Plain of southeastern Idaho were analyzed for composition. Rodent remains in general and those of cricetid mice in particular occurred more frequently in scats of red foxes during all seasons of the year than any other food items identified. Scats of coyotes differed significantly in content from scats of red foxes during winter and contained primarily pygmy rabbit remains. In summer, remains of pygmy rabbits, sheep, ground squirrels, yellow-bellied marmots, arthropods, and vegetation were formed more frequently in scats of coyotes and remains of cricetid mice occurred more frequently in scats of red foxes. Red foxes and coyotes generally consumed similar food items but in different proportions. Based on the location of scats that were collected, red foxes and coyotes largely used different portions of the study area. Reasons for the preferential usage of habitat are discussed.     

Hatching chronology of Blue Grouse in northeastern Oregon

Hatching chronology of Blue Grouse ( Dendragapus obscurus ) in northeastern Oregon was determined from 431 immatures examined from 1981 to 1985. Young hatched from 1 May through 8 July; median hatching dates for the five years ranged from 27 May to 5 June. Peak hatching in Oregon occurred from one to four weeks earlier than in most portions of the range of Blue Grouse but were similar to north central Washington and Idaho. Variations in hatching dates possibly were related to rainfall.       

Notes on American Sitona (Coleoptera: Curculionidae), with three new species

Historical notes extracted from a taxonomic revision of American representatives of Sitona Germar are presented. Described as new to science are Sitona alpinensis (Utah to Northwest Territories), bryanti (Arizona), and oregonensis (Oregon to Washington).     

Habitat use patterns within the home range of pygmy rabbits ( Brachylagus idahoensis ) in southeastern Idaho

Pygmy rabbits ( Brachylagus idahoensis ) are a small sagebrush ( Artemisia tridentata ) obligate lagomorph found within the Great Basin of northwestern United States. Because of its reliance on sagebrush, this species is thought to be experiencing a major range reduction as a result of loss of sagebrush habitat. To aid in conservation of this species, we need to better understand its use of the sagebrush environment. We estimated summer home range use patterns by relocating 5 radio-collared pygmy rabbits (3 females and 2 males) over a 24-hour cycle. We then compared soil texture, shrub density, height, and canopy cover between areas close to burrow entrances and areas of high use and low use. Mean home range sizes of female and male rabbits were 37.2 and 67.9 ha, respectively. Rabbits had disproportionate amounts of time (68.4% ± 9.1, s￣x ) and travel (63.0% ± 5.7, s￣x ) in areas within a 60-m radius of their burrows. Soil texture did not differ among the 3 areas, but shrub density, specifically big sagebrush, and forb density were significantly higher close to the burrow than in the high- and low-use areas. We conclude that pygmy rabbits are possibly burrow obligates and that their abundance and distribution are likely limited by available burrow sites.     

Notes on mycophagy in four species of mice in the genus Peromyscus

We examined stomach contents of 426 Clethrionomys , 217 C. californicus from western Oregon and 209 C. gapperi from widely scattered areas across North America. Clethrionomys californicus consumed fungi of 28 genera. Clethrionomys gapperi from the Rocky Mountains westward consumed fungi of 23 genera, whereas C. gapperi east of the Rocky Mountains consumed fungi of 7 genera. This study supports the conclusions of an earlier study, limited to Oregon and Washington, that food habits of C. californicus and C. gapperi are more closely related to habitat than to species or subspecies of vole.     

Mycophagy of red-backed voles, Clethrionomys californicus and C. gapperi

We examined stomach contents of 426 Clethrionomys , 217 C. californicus from western Oregon and 209 C. gapperi from widely scattered areas across North America. Clethrionomys californicus consumed fungi of 28 genera. Clethrionomys gapperi from the Rocky Mountains westward consumed fungi of 23 genera, whereas C. gapperi east of the Rocky Mountains consumed fungi of 7 genera. This study supports the conclusions of an earlier study, limited to Oregon and Washington, that food habits of C. californicus and C. gapperi are more closely related to habitat than to species or subspecies of vole.     

First record of multiple paternity in the pygmy rabbit ( Brachylagus idahoensis ): evidence from analysis of 16 microsatellite loci

Although promiscuity is believed to be common among leporids, little is known about the mating system of free-ranging pygmy rabbits ( Brachylagus idahoensis ). We used 16 polymorphic microsatellite markers and DNA extracted from tissue samples of 10 rabbits from 2 litters collected in east central Idaho to evaluate paternity. We incorporated maternal genotypes for better resolution and employed an exclusion approach to detect multiple paternity. Our results demonstrated multiple paternity at 6 of the 16 loci tested for each litter. These findings support the expectation that pygmy rabbits have a promiscuous mating system. It has been proposed that multiple paternity could lead to higher effective population sizes and help small populations maintain diversity. Given that pygmy rabbits persist in small and fragmented populations, a promiscuous mating system might be important for maintaining genetic diversity in free-ranging populations and could be advantageous for the captive breeding program. Aunque se cree que la promiscuidad es común entre los lepóridos, se conoce poco sobre el sistema de apareamiento del conejo pigmeo ( Brachylagus idahoensis ) en condiciones silvestres. Utilizamos 16 marcadores de microsatélites polimórficos y ADN extraído de muestras de tejido de 10 conejos de 2 camadas colectadas en la parte este central de Idaho para evaluar su paternidad. Los genotipos maternos fueron incorporados para lograr una mayor resolución y empleamos un método de exclusión para detectar la paternidad múltiple. Nuestros resultados demuestran paternidad múltiple en 6 de los 16 loci examinados en cada camada. Estos resultados apoyan la suposición de que los conejos pigmeos tienen un sistema de apareamiento promiscuo. Se ha propuesto que la paternidad múltiple podría conducir a tamaños efectivos de la población más grandes y ayudar a que las poblaciones pequeñas mantengan la diversidad. En vista de que el conejo pigmeo persiste en poblaciones pequeñas y fragmentadas, un sistema de apareamiento promiscuo podría ser importante para mantener la diversidad genética en poblaciones silvestres y podría resultar provechoso para el programa de cría en cautiverio.     

Distribution and postbreeding environmental relationships of northern leopard frogs ( Rana [ Lithobates ] pipiens ) in Washington

Northern leopard frogs ( Rana [ Lithobates ] pipiens ) are considered sensitive, threatened, or endangered in all western states and western Canadian provinces. Historically present in eastern Washington in 6 major river drainages, leopard frogs are now only known to occur at 2 localized areas in the Crab Creek drainage in Grant County. During the summers of 2002–2005, we surveyed both areas to document extent of leopard frog distributions and to describe habitat and vertebrate community characteristics associated with leopard frog site occupancy. At Gloyd Seeps, 2 juvenile leopard frogs were observed in a total of 8.2 person-days of searching along a 5-km stream reach. At Potholes Reservoir, we surveyed 243 wetland sites in 7 management units known to have been occupied by leopard frogs during the 1980s. We confirmed leopard frog presence at only 87 sites (36%) in 4 management units. Site occupancy models for individual ponds indicated that, compared to unoccupied sites, occupied sites had slightly greater pond depths, less tall emergent vegetation, more herbaceous vegetative cover, and fewer neighboring ponds containing nonnative predatory fish. Models developed at the 1-km 2 scale indicated that occupied areas had greater average midsummer pond depths, fewer ponds occupied by bullfrogs ( Rana [ Lithobates ] catesbeiana ) and carp ( Cyprinus carpio ), and more herbaceous vegetation surrounding ponds. The Gloyd Seeps population now appears defunct, and the Potholes Reservoir population is in sharp decline. Unless management actions are taken to reduce nonnative fish and bullfrogs and to enhance wetland vegetation, leopard frogs may soon be extirpated from both sites and possibly, therefore, from Washington.     

Food of townsend ground squirrels on the Arid Land Ecology Reserve (Washington)

Diets of townsend ground squirrels were quantified from the Arid Land Ecology (ALE) Reserve eastern Washington.     

Leeches of the Snake River in Idaho and Oregon: paleodrainage implications of Mooreobdella microstoma

Leech species of the mid-Snake River of Idaho and Oregon are described, and the distribution of the extant leech Mooreobdella microstoma Moore in the Snake River paleodrainage is delineated. Samples were collected from aquatic surveys in the Snake River using suction dredging by the Idaho Power Company and U.S. Bureau of Reclamation between 1995 and 2006. Supplementing these surveys, opportunities were provided for leech identification in water-quality analyses in Arizona and Wyoming and in other surveys in California, Oregon, Washington, and Idaho. Eight species of leeches were found in the Snake River surveys. Erpobdella parva Moore was the most widely distributed species, occurring both above and below Shoshone Falls. Mooreobdella microstoma was widely distributed below Shoshone Falls. Other leech species were rare, although Helobdella stagnalis Linnaeus was very common above and less common below Shoshone Falls, a natural barrier to the anadromous fish. Mooreobdella microstoma is an extant species that links the Snake River to the lower Colorado River by various paleodrainages. It probably colonized the Snake River by upstream movement, whereas Erpobdella parva likely colonized this river by downstream movement.     

Historic expansion of Juniperus occidentalis (western juniper) in southeastern Oregon

The chronology of Juniperus occidentalis (western juniper) expansion in eastern Oregon, the effect of plant canopy and interspace on J. occidentalis seedling establishment and growth rates, and the age of J. occidentalis maximum reproductive potential were determined. Measurements were recorded in twenty-two 0.4-ha plots established in sagebrush-grassland communities and six 0.1-ha plots in Populus tremuloides (quaking aspen) communities. J. occidentalis began increasing during the 1880s in stands containing > 130 yr old. Relatively steady establishment ensued into the 1950s and then began to progress at a geometric rate in the 19602. J. occidentalis encroachment into aspen stands began between 1910 and 1920. The largest proportion of juvenile trees established beneath Artemisia species in sagebrush-grassland communities. J. occidentalis trees appeared to reach full reproductive potential at > 50 yr of age. The ratio of male:female trees increased from 1.7 in scattered J. occidentalis stands to 3.8 in closed stands. The initiation of J. occidentalis encroachment during the late 1800s coincides with optimal climatic conditions for Juniperus berry production and establishment, reduced fire-return intervals, and heavy livestock grazing. The accelerated increase in J. occidentalis expansion since 1960 may be due to the continued absence of fire, abundant woody plant cover, and the large increase in J. occidentalis seed production.