The relative exploitation of annuals as larval host plants by European butterflies

Theoretically, Lepidoptera should be able to adapt to using annuals as larval host plants through increased development rates and migration capacity. Even so, we show that annuals are used less frequently as host plants than expected among British and continental European butterflies. In particular, no example has been found of a European butterfly monophagous on an annual plant over its entire range. Use of annuals is proportionately greater among species that exploit increasing numbers of host plants and among subsidiary host plants than among primary (main) host plants. Annuals as host plants change status as habitat components with changes in species' spatial dynamics. The statistical findings point to perennials as providing host plant refuges, whereas the few case examples of site monophagy suggest that annuals can become valuable complementary resources during range extensions such as those currently associated with climatic warming. Annuals are more likely to be used in highly restricted circumstances, when environmental conditions allow the plants to persist over prolonged periods (i.e. when they are behaving like biennials) or when their spatial predictability is high because of low seed dispersal.     

Distribution of the Shoshone scuplin ( Cottus greenei: Cottidae) in the Hagerman Valley of south central Idaho

Cottus greenei, a potentially threatened species endemic to Idaho, was collected from 49 localities in 25 springs/streams in south central Idaho. Most localities were along the north bank of the Snake River in waters of the Thousand Springs formation, Gooding County. One population was found in a spring in the main Snake River. Another sculpin, Cottus bairdi, was collected with C. greenei at 23 locations in 16 springs/streams. Confusion concerning the type locality of Cottus greenei is discussed.        

Insect-mediated pollination in slickspot peppergrass, Lepidium papilliferum L. (Brassicaceae), and its implications for population viability

Field experiments on the pollination biology of slickspot peppergrass, Lepidium papilliferum L. (Brassicaceae), a rare species endemic to microsites in sagebrush-steppe habitat in southwestern Idaho, were conducted at 2 sites from May to July 2001. Site KB contained over 10,000 plants, whereas site WG contained less than 150 plants. Insect exclusion experiments revealed that seed production in L. papilliferum is dependent on insect-mediated pollination; median percent seed set dropped from 70% to 2% when insects were excluded from flowers. A total of 25 insect families from 5 orders visited L. papilliferum flowers: 24 families at KB and 11 families at WG. Only 9 families contained more than trace amounts of pollen on their bodies: Hymenoptera-Anthophoridae, Apidae, Colletidae, Halictidae, Sphecidae, Vespidae; Coleoptera-Cerambycidae, Dermestidae; Diptera-Syrphidae. Insects from these families are likely responsible for pollination of L. papilliferum , although some may be of only minor significance due to their infrequent visits to flowers. Two of the 4 most common and pollen-laden insects found at KB, honey bees ( Apis mellifera ) and colletid bees, were absent or rare at WG. Three other pollen-carrying families present at KB, Sphecidae, Vespidae, and Halictidae, were not found at WG. We raise several possible explanations for this disparity in pollinator communities between sites and discuss the importance of pollinator diversity to the long term viability of L. papilliferum .     

The short song of Brewer's Sparrow: individual and geographic variation in southern Idaho

Brewer's Sparrows ( Spizella breweri ) have two song types--a ""short"" song that has 1 to 3 trill types and a ""long"" song that has 5 to 10 or more trill types. I describe the short song and examine patterns of individual and geographic song variation from 15 sites on the Snake River Plain in southern Idaho. Territorial males sang the short song regularly during the breeding season. Two-trill song types comprised 72.9% of all song types, with 3-trill types (18.8%) and 1-trill types (8.2%) less frequent. Over 90% of the males sang their song type(s) essentially without variation. Many trill types appeared most often in only 1 of 3 possible song positions, i.e., 1st, 2nd, or 3rd trill. Trill types that occurred in different song positions differed in syllables per second, trill and syllable duration, and frequency variables. First trill types were more variable than 2nd or 3rd trill types. There was no evidence that birds at sites closer together shared more trill types or pairs of trill types than those farther apart. There was no tendency for territorial neighbors to sing similar song types. Brewer's Sparrows' small territories, dense populations, and apparently high rate of annual turnover may mediate against the evolution of song sharing or vocal dialects.     

Simulation modeling of American marten ( Martes americana ) populations: vulnerability to extinction

American marten ( Martes Americana ) are medium-sized mammalian carnivores inhabiting forest communities across northern North America. Martens are susceptible to local extinction from habitat alterations, trapping, and other factors. We (RCL) developed a population model called VORTEX to estimate extinction probabilities for marten populations as a management tool. The model permits managers to simulate various levels of timber harvesting, commercial trapping, and other factors to estimate their effects on marten populations. This paper describes this model and illustrates its benefits by using marten data from the Greater Yellowstone Ecosystem of northwestern Wyoming. Results are preliminary. Populations of 50 and 100 martens were simulated. The most optimistic scenario with populations of 100 individuals, no trapping, no logging, and no migrants showed a probability (66%) of surviving 100 years. Extinction probabilities were sensitive to immigration and emigration rates. Numerous scenarios were simulated and showed a range of results. Results of population viability analysis can be translated into area requirements if densities are known or can be estimated. In turn, various habitat patches and interconnecting corridors can be examined for their ability to support viable marten populations. Population modeling is invaluable to ""adaptive management"" of martens as well as other species.     

Naturalization of plains cottonwood ( Populus deltoides subsp. monilifera ) along river drainages west of the Rocky Mountains

Historic botanical surveys documented that the natural distribution of the plains cottonwood ( Populus deltoides subsp. monilifera ) was limited to semiarid drainages east of the Rocky Mountains. Recently, a number of isolated populations of plains cottonwood have been found along the Kootenai, lower Snake, and Columbia Rivers and their tributaries. We used isozyme analysis to assess the genetic structure of these Pacific Northwest (PNW) populations in relation to native cottonwood populations east of the Rocky Mountains. These genetic data along with field surveys (dbh, age estimates) and cadastral field survey notes (mid-1800s) were used to understand the origin of these disjunct populations (i.e., relictual natives versus naturalized introductions). Genetic analyses revealed high levels of genetic diversity within and among PNW populations as well as hybridization with black cottonwood ( P. trichocarpa ). The observed range of genetic variation for PNW populations was similar to that of native cottonwood populations. Collectively, these data confirm that these scattered populations are plains cottonwood ( Populus deltoides subsp. monilifera ). Age estimates of the largest individuals found within study populations ranged from 27 to 51 years. Cadastral field surveys also noted the absence of woody vegetation along the lower Snake and Columbia Rivers. Considered together, the data suggest that these populations are of recent origin. The high levels of observed genetic variation are consistent with the reproductive biology of Populus spp. (i.e., obligate outcrossing and widespread dispersal of pollen and seed by wind and water) and a recurrent introduction of plains cottonwood throughout the study area.     

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.     

Experimental manipulations of precipitation seasonality: effects on oak ( Quercus ) seedling demography and physiology

Predicted changes in regional precipitation patterns and soil moisture caused by anthropogenic trace gas emissions may affect the distribution and abundance of woody plants in arid and semiarid regions. To test the response of woody plants to potential changes in precipitation regimes, we manipulated summer and winter precipitation on plots that contained seedlings of Quercus emoryi Torr. (Emory oak), the dominant tree in oak savannas of the southwestern United States. Throughout the growing season, we monitored seedling survival and physiology (predawn leaf water potential, midday instantaneous gas exchange, and leaf carbon isotope discrimination). Seedling survival and physiological performance differed little between treatments, which embodied 50% changes to quantities of summer and winter precipitation, and encompassed a continuum of precipitation from 359 mm · year -1 to 846 mm · year -1 . However, survival and physiological performance of seedlings were negatively impacted by seasonal environmental conditions common to all treatments, especially during the annual pre-'monsoon' drought. Seedling predawn leaf water potentials, net CO 2 assimilation, and stomatal conductance indicate that growing conditions for Q. emoryi seedlings at this site are generally restricted to periods with adequate soil moisture (i.e., April and August). Results contrast with an assumption implicit to the ""two-layer"" soil water resource partitioning hypothesis that woody plants in all life history stages are more dependent upon winter than summer precipitation. In fact, summer precipitation appears more important than winter precipitation for Q. emoryi seedling recruitment and growth.     

Differential utilization of bat boxes by house wrens ( Troglodytes aedon )

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;} Pine boxes nailed to trees in four habitat types in southeastern Utah as roosting sites for bats proved ineffective for bats but were utilized by house wrens in all but one habitat. Boxes were most often utilized in the aspen habitat. Hypotheses to account for differential utilization are presented.       

An ecological study of bristlecone pine ( Pinus longaeva ) in Utah and eastern Nevada

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;} This paper presents data on the distribution of Pinus longaeva on the Markagunt Plateau, Utah; and the Snake, Egan, and White Pine ranges of eastern Nevada. It also presents data on the present-day density and age structure of three P. longaeva populations and the growth rates of individual trees within these populations. Conifer species richness and the relative abundance of P. longaeva varies clinally from the Markagunt Plateau to the White Pine Range. The Markagunt Plateau has relatively high conifer species richness (10 species) and low relative abundance of P. longaeva (1%). The White Pine Range has low conifer richness (4 species) and high P. longaeva relative abundance (34%). Individual tree growth rates were low but highly variable in all populations studied. The three populations studied had mixed age structures with a general trend of more younger individuals at the lower elevations. Possible explanations for the present distribution of P. longaeva and the population structures observed are discussed.     

Phylogenetic divergence in a desert fish: differentiation of speckled dace within the Bonneville, Lahontan, and upper Snake river basins

Historical events have had a great impact on the biogeography of fishes of western North America. We examined the genetic variation of the speckled dace ( Rhinichthys osculus ) to determine the effects on this species of extensive hydrological changes during the last 10 million years in the Bonneville and Lahontan basins of the Great Basin and the upper Snake River Basin. Eight hundred sixty-nine base pairs of the mitochondrial gene cytochrome b were sequenced from 97 individuals representing 22 populations within these 3 basins, as well as from 2 individuals of longnose dace ( Rhinichthys cataractae ) that served as outgroups. Additionally, 13 speckled dace sequences representing 3 Bonneville populations were used from GenBank. Phylogenetic relationships were reconstructed using maximum parsimony and maximum likelihood criteria. Analysis of molecular variance was used to determine population structure and to estimate the amount of gene flow across the community boundaries. Three distinct clades were reconstructed representing the Lahontan Basin, the northern Bonneville and upper Snake River basins, and the southern Bonneville Basin. Additionally, most of the population structuring was explained by variation among basins (65.33%). Speckled dace demonstrated high genetic variation. As hypothesized, the northern and southern Bonneville specimens formed separate clades; however, the southern Bonneville clade was basal to a sister clade formed by the northern Bonneville/upper Snake River and Lahontan clades. These relationships indicate that Pliocene connections between the Snake, Lahontan, and Bonneville drainages, rather than more recent Pleistocene connections, best explain population structuring in speckled dace.     

Spawning ecology of finespotted Snake River cutthroat trout in spring streams of the Salt River valley, Wyoming

We studied spawning ecology of cutthroat trout ( Oncorhynchus clarki ) in streams that originate as springs along the Salt River, a Snake River tributary in western Wyoming. We assessed (1) relative numbers of upstream-migrant and resident adults present during the spawning period in spring streams, (2) influence of habitat modification on use of spring streams for spawning, and (3) habitat features used for spawning in spring streams. Four spring streams were studied, 2 with substantial modification to enhance trout habitat and 2 with little or no modification. Modifications consisted primarily of constructing alternating pools and gravel-cobble riffles. Only a small portion of adult fish in spring streams during the spawning period had migrated upstream from the Salt River between March and the middle of June. Larger numbers of adult fish and more redds were observed in the 2 modified streams compared with the 2 streams with little or no modification. Most spawning occurred on constructed riffles with small gravel and over a narrow range of depths and velocities. Cutthroat trout, rainbow trout ( Oncorhynchus mykiss ), and their hybrids were observed in 1 stream with habitat modifications, indicating that measures to halt invasion by rainbow trout, as well as habitat improvement, are needed to preserve this native trout within the Salt River valley.     

Ecological review and management recommendations for recovery of the endangered Gila topminnow

Ecology of the endangered Gila topminnow is reviewed, described, and reconstructed; natural conditions are placed in perspective with human-altered habitats of today. In the natural state of waxing and waning of habitat size as a function of precipitation patterns are catastrophic events such as severe winter cold, the species in the past likely underwent dramatic expansions and contractions in population size and geographic range. Today, population expansions are unlikely because of constraints imposed by human activities. The original patterns of dispersal from refugia in ""good"" times and retreat in ""bad"" times, if they are to occur, must be re-created through human translocation. Further, most refugia now are destroyed or inaccessible to recolonization, so remnant, natural populations, along with established, transplanted stocks of appropriate size and genetic quality, need protection. Populations also must be established and maintained in artificial refugia. Last, even if connectedness were to be reestablished and refugia provided, intervening habitats harbor introduced piscivores such as western mosquitofish that interdict and eat dispersing topminnows and their progeny. Eliminatoin, exclusion, or management against such offending species is mandatory to prevent topminnow extinction and achieve recovery.     

Postemergence development and interyear residence of juvenile Columbian ground squirrels in the Idaho Primitive Area

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;} Monthly percent nutrient and moisture levels of plant species on two summer ranges in the River of No Return Wilderness Area of Idaho were determined. Festuca idahoensis exhibited the highest average crude protein content of graminoids on both study areas. Achillea millefolium and Balsamorhiza saggittata at Rush Point and Trifolium spp. and Achillea millefolium at Cold Meadows possessed the highest mean crude protein content of the forbs examined. Grasses exhibited greater average seasonal levels of crude fiber, and forbs generally contained significantly larger levels of Ca, P, and moisture.     

Plant nutrient levels on two summer ranges in the River of No Return Wilderness Area, Idaho

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;} Monthly percent nutrient and moisture levels of plant species on two summer ranges in the River of No Return Wilderness Area of Idaho were determined. Festuca idahoensis exhibited the highest average crude protein content of graminoids on both study areas. Achillea millefolium and Balsamorhiza saggittata at Rush Point and Trifolium spp. and Achillea millefolium at Cold Meadows possessed the highest mean crude protein content of the forbs examined. Grasses exhibited greater average seasonal levels of crude fiber, and forbs generally contained significantly larger levels of Ca, P, and moisture.     

Population cycles of Wahweap Milkvetch on the Henry Mountains and seed reserve in the soil

A population outbreak of Wahweap milkvetch ( A. lentiginosus var. wahweapensis Welsh) occurred in the Henry Mountains area of southeastern Utah in 1985 and 1986, causing extensive locoweed poisoning in cattle grazing these winter ranges. Weather conditions supporting this population outbreak included above average precipitation in the fall of 1984 and 1985, which presumably allowed germination of seed lying dormant in the soil. Above average spring precipitation in the subsequent year supported the population growth. Part of the population died in the summer of 1985, and nearly all plants died in the summer of 1986. Historically, population outbreaks occurred every six to eight years: 1949, 1957, 1965, 1973, 1979, and 1985-1986. Correlation with weather records indicated that population outbreaks occurred in years of high spring and total annual precipitation. Wahweap milkvetch seed lying dormant in the soil ranged from 940 to 4,346 seed/m 2 where old stands occurred, and 20 to 40 seed/m 2 where old plants were not evident. Sufficient seed remains in the soil to cause future population outbreaks.     

The relationships among plant cover, density, seed rain, and dispersal of Bromus tectorum in high-elevation populations

Normal 0 false false false EN-US X-NONE X-NONE /* 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 invasive species Bromus tectorum L. is recognized as one of the most ecologically and economically devastating weeds in the western United States. Although B. tectorum has been studied extensively, few studies have examined its dispersal and spread. We collected data from sites with B. tectorum in and around Rocky Mountain National Park to quantify the relationships between plant cover/density and seed rain and dispersal distance. Results suggest that there is a positive relationship between density within a patch and local seed rain and that B. tectorum exhibits relatively limited short-distance dispersal (where seeds fell in close proximity to plants and no seeds were found to have dispersed more than 0.1 m from the edge of a patch). These data can inform modelers and managers who are attempting to better understand population dynamics and options for controlling this species. La especie invasora Bromus tectorum L. se considera una de las hierbas más devastadoras ecológica y económicamente del oeste de Estados Unidos. Aunque se ha estudiado extensamente, se han hecho pocos estudios sobre su dispersión y distribución. Colectamos datos de sitios donde crecía B. tectorum en Rocky Mountain National Park y sus alrededores para cuantificar la relación entre la cobertura y la densidad de plantas, la lluvia de semillas y la distancia de dispersión. Los resultados sugieren que hay una relación positiva entre la densidad dentro de una parcela y la lluvia local de semillas, y que B. tectorum exhibe una distancia de dispersión relativamente corta (las semillas caen cerca de las plantas y no encontramos ninguna semilla que se hubiera dispersado a más de 0.1 m del borde de la parcela). Estos datos pueden informar a los modeladores y administradores en su esfuerzo por comprender la dinámica poblacional y las opciones de control para esta especie.     

Riparian vegetation along the middle Snake River, Idaho: zonation, geographical trends, and historical changes

A baseline study was conducted on an 83-km free-flowing reach of the Snake River between Swan Falls Dam and the Idaho-Oregon border. The research had 2 components: (1) field characterization and inventory of existing riparian flora, vegetation, and environment (soils, topography, streamflow), and (2) determination and mapping, using a geographic information system, of historic changes in riparian vegetation based on a time series (1938-39, 1957, 1969, 1987) of aerial photographs. The flora was diverse, with 185 species of vascular plants identified, 63 of which were exotics. Vegetation was structured vertically along the riverbank gradient into lifeform-defined habitat types: emergent, riparian shrub-forb, tree, transitional grass-shrub, and upland. Riverbank seepage, probably of agricultural origin, blurred zonation patterns on some sites and added species to the overall flora. Upstream-downstream differences existed in the physical characteristics and vegetation of river subreaches. Coverage of riparian woodland, island riparian and total riparian vegetation, and area of islands increased since the 1930s, with the greatest changes in the 1969-1987 interval. Possible contributing facts were (1) significant declines in annual minimum flows since the 1950s, (2) decreases in peak flows following the completion of Swan Falls Dam and some upstream dams since the 1920s, (3) introduction and spread of exotic tree species ( Elaeagnus angustifolia and Tamarix spp.) and (4) possible effects of intensive agriculture on river sediment load and soil nutrients. The introduction and proliferation of purple loosestrife ( Lythrum salicaria ) could have considerable future effects on vegetation-channel dynamics in the middle Snake River.     

Regional assessment of wadable streams in Idaho, USA

There has been a resurgence in applying bioassessment techniques for evaluating and monitoring the biological integrity of stream ecosystms. In all cases biological metrics have been refined to account for regional variation in aquatic habitats and fauna. This study evaluated environmental and macroinvertebrate properties for wadable streams in 3 major ecoregions of Idaho: Northern Basin and Range, Snake River Plain, and Northern Rocky Mountain. These 3 ecoregions constitute > 80% of the land area in Idaho. Reference streams were delineated from test streams in each ecoregion using standard habitat assessment protocols. (Plafkin et al. 1989). Multiple discriminant analysis effectively determined habitat (quantified measures) and macroinvertebrate differences between reference and test streams within ecoregions, although the results suggested that quantifiable habitat measures (e.g., water chemistry and nutrients) and biotic measures based on taxonomic groups (e.g., % Elmidae) improved the discriminatory power of evaluation procedures. Our results support the contention of a multi-metric approach for assessing differences among streams within an ecoregion. Lastly, individual metrics differed in their importance for evaluating stream condition among ecoregions, further emphasizing the importance of regionally stratifying metric selection or scoring procedures.     

Conservation, status, and life history of the endangered White River spinedace, Lepidomeda albivallis (Cyprinidae)

Lepidomeda albivallis (White River spinedace), a fish species endemic to the White River, Nevada, appeared headed toward extinction. In 1991 only 1 population remained, and it comprised fewer than 50 individuals in a 70-m stream reach. We monitored population recruitment and distribution and studied life history and habitat use from 1993 through 1998. We determined that L. albivallis was not reproducing and was continuing to decline, and as an emergency measure we relocated the population (14 in spring 1995 and 6 in spring 1996) downstream 200 m to a secure habitat that we judged more favorable for reproduction. The relocated population reproduced, and by September 1998 it had increased to 396 individuals that inhabited more than 1 km of stream including both pond and stream habitats. In streams they oriented near the bottom but frequently moved up in the water column to strike at drift items. Gut analysis of museum specimens indicated L. albivallis is omnivorous but feeds primarily upon aquatic invertebrates. Conservation of L. albivallis will require reestablishing additional populations within its former range.