Bitterroot Mountains Research Articles

Capturing the complexity of soil evolution: Heterogeneities in rock cover and chemical weathering in Montana's Rocky Mountains

We investigate the relationship between chemical weathering, persistence of soil cover, and topography in two neighboring mountain ranges in the northern Rockies of western Montana, USA. We augment existing tools for measuring chemical weathering with adjustments for both local and landscape-scale contributions from unweathered rock fragments, boulders, and bedrock exposure. Adjusted weathering intensities recognize that quantifying weathering in mountainous systems should account for rock exposure, rather than focusing solely on fine-grained soil mantles. Our study systems' distinct morphologies are shaped by their unique climate histories. The previously glaciated Bitterroot Mountains consist of steep hillslopes with abundant rock cover, while the neighboring unglaciated Sapphire Mountains display convex, soil-mantled hillslopes. Over 380 soil thickness measurements, 118 analyses of soil and rock geochemistry, and digital terrain analysis reveal that patchy soils in the bedrock-rich system are roughly half as thick as those in the continuously-soil-mantled landscape, and ~45% less weathered, despite wetter conditions that would be expected to enhance weathering. These disparities increase when accounting for coarse rock fragments in soils and bedrock cover across the study catchments. The near continuously soil-mantled Sapphire system experiences ~1.5 times greater weathering intensity at a catchment scale compared to the bedrock-rich Bitterroot system. Rock exposure across the mountainous study system increases with increasing slope gradient. However, we find no clear threshold at which soils decrease in abundance or weathering intensity, and soils are surprisingly resilient even at the steepest hillslopes (comprising ~60% of the landscape area at slopes >30°). Our new data quantify soil abundance and chemical weathering intensity at both local and landscape scales. This work highlights how measurements of soil and rock cover need to be incorporated into studies quantifying chemical weathering, as traditional approaches may significantly overestimate and mischaracterize weathering regimes in mountain environments.

Large wood and sediment storage in a mixed bedrock-alluvial stream, western Montana, USA

Sediment storage by instream wood in forested mountain streams mediates sediment movement from hillslopes through the channel network and can alter channel morphology at multiple spatial scales. Mixed bedrock-alluvial channels are prevalent in mountain stream networks, yet the distribution and geomorphic impact of large wood within these streams are poorly understood. To estimate how the distribution of large wood in a mixed bedrock-alluvial stream relates to sediment storage, we measured and characterized large wood, and we surveyed the volume of associated sediment within a stream in the Bitterroot Mountains, Montana. The upstream portion of the study reach is predominantly alluvial and the downstream portion has significant bedrock exposure along the channel bed and banks. Wood volume and sediment storage in the mixed bedrock-alluvial subreach are 50% and 15%, respectively, of those measured in the alluvial subreach. Most wood is organized into jams, and two channel-spanning jams within the upstream subreach account for 50% and 80% of the reach-averaged wood and sediment volume, respectively. The volume of sediment stored by wood in the full reach is the same order of magnitude as the estimated annual bedload export. Our study highlights the interactions among channel form and the fluxes and storage of wood and sediment. Wood that forms channel-spanning jams, which store a disproportionate amount of wood and sediment in the study reach, may accentuate differences between alluvial and bedrock-dominated subreaches in mountain stream networks, by promoting sediment deposition and storage upstream and by reducing sediment supply to downstream reaches.

Clark’s Nutcrackers (<i>Nucifraga columbiana</i>) caching Whitebark Pine (<i>Pinus albicaulis</i>) seeds in trees

On 17 September 2017, I observed two Clark’s Nutcrackers (Nucifraga columbiana) from 8–10 m distance as they cached seeds in a stand of dead Whitebark Pines (Pinus albicaulis) at 2500 m elevation on Saint Mary Peak in the Bitterroot Mountains of Ravalli County, Montana. Over 5 minutes, the nutcrackers created 14 caches in seven different multi-trunk tree clusters in an area of about 50 m2. All caches appeared to be single Whitebark Pine seeds, positioned 2–5 m (mostly 3–4 m) above ground in dead trees. Of the 14 caches, three were placed under loose pieces of bark on a trunk (one) or large limb (two), and the remaining 11 were in encrustations of American Wolf Lichen (Letharia columbiana) growing on branches of the dead trees. Nutcrackers are known to sometimes cache seeds above ground in trees during the late summer and autumn harvest of pine seeds, but usually not to the exclusion of other microsites. The ground at the Montana site was covered by 7–9 cm of fresh snow that fell the previous day, which may have encouraged the nutcrackers to place all of their seed caches above ground in trees.

First Record of the Land Snail <i>Pristiloma idahoense</i> (Gastropoda: Pristilomatidae) for Montana

The land snail Pristiloma idahoense (Pilsbry, 1902) is reported from Montana for the first time. Five live individuals were found under downed wood beneath a mature coniferous forest canopy at 1670 m elevation in the Big Creek drainage of the Bitterroot Mountains, Ravalli County, Montana. This location extends the known range approximately 75 km east and over the crest of the Bitterroot Mountains from the nearest sites in Idaho County, Idaho and supports the hypothesis that the terrestrial mollusc fauna of Montana west of the continental divide has been strongly influenced by a molluscan radiation, which developed in a northern Idaho Pleistocene refuge. The probable route of dispersal for P. idahoense between the Bitterroot Mountains of Montana and the adjacent Lochsa River drainage of Idaho was over the lower mountains to the north in the Lolo Pass area.

Integrating resource selection into spatial capture‐recapture models for large carnivores

Wildlife managers need reliable methods to estimate large carnivore densities and population trends; yet large carnivores are elusive, difficult to detect, and occur at low densities making traditional approaches intractable. Recent advances in spatial capture‐recapture (SCR) models have provided new approaches for monitoring trends in wildlife abundance and these methods are particularly applicable to large carnivores. We applied SCR models in a Bayesian framework to estimate mountain lion densities in the Bitterroot Mountains of west central Montana. We incorporate an existing resource selection function (RSF) as a density covariate to account for heterogeneity in habitat use across the study area and include data collected from harvested lions. We identify individuals through DNA samples collected by (1) biopsy darting mountain lions detected in systematic surveys of the study area, (2) opportunistically collecting hair and scat samples, and (3) sampling all harvested mountain lions. We included 80 DNA samples collected from 62 individuals in the analysis. Including information on predicted habitat use as a covariate on the distribution of activity centers reduced the median estimated density by 44%, the standard deviation by 7%, and the width of 95% credible intervals by 10% as compared to standard SCR models. Within the two management units of interest, we estimated a median mountain lion density of 4.5 mountain lions/100 km2 (95% CI = 2.9, 7.7) and 5.2 mountain lions/100 km2 (95% CI = 3.4, 9.1). Including harvested individuals (dead recovery) did not create a significant bias in the detection process by introducing individuals that could not be detected after removal. However, the dead recovery component of the model did have a substantial effect on results by increasing sample size. The ability to account for heterogeneity in habitat use provides a useful extension to SCR models, and will enhance the ability of wildlife managers to reliably and economically estimate density of wildlife populations, particularly large carnivores.

A First Generation Heterobasidion Hybrid Discovered in Larix lyalli in Montana

On September 25, 2010, a wood sample was collected from an entirely decayed root ball of an alpine larch (Larix lyallii Parl.), 10 cm in diameter at breast height, recently downed, but still green. No attempts were made to determine whether the decay progressed into the stem. The discovery occurred in a stand in the Bitterroot Mountains, south of Darby, Montana (elev. 2,530 m; 45.893528° N, 114.278322° W). Several adjacent alpine larches were either dead or displayed thin crowns, and an old Heterobasidion basidiocarp was found on the decayed root ball of a neighboring dead tree, suggesting the presence of a root disease pocket. The stand is mature and composed of alpine larch, whitebark pine (Pinus albicaulis Engelm.), and a few subalpine firs (Abies lasiocarpa (Hooker) Nuttall), but only larches were symptomatic. No stumps were visible, and the site is in a designated wilderness area characterized by minimal forest management. Wood chips displaying a white rot with bleached speckles were plated on 2% malt agar, and cultures displaying the typical Heterobasidion anamorph (Spiniger meineckellus) were visible after 7 days. DNA was extracted from two distinct cultures, and the sequences of three nuclear loci, namely the internal transcribed spacer, the elongation factor 1-alpha, and the glyceraldehyde 3-phosphate dehydrogenase, were analyzed. The sequence of the mitochondrial ATPase was also sequenced. All loci were amplified using the primers indicated in Linzer et al. (2). Sequences of all three nuclear loci (GenBank Accession Nos. KF811480 to 82) unequivocally indicated both isolates to be first generation hybrids between H. irregulare (Underw.) Garbel. & Otrosina and H. occidentale Otrosina & Garbel. Cumulatively, sequences were heterozygous at over 40 positions in all three loci, and for the presence of two indels (one in ITS, one in EF 1-alpha). Polymorphisms and indels indicated alleles from both species were present in these heterokaryotic (ploidy n+n) isolates. The mitochondrial ATPase (KF811483 to 84) indicated instead the cytoplasm belonged to H. occidentale, suggesting that species was the first to be established in the infected tree and was either dikaryotized by a basidiopsore of the other species, or subject to nuclear re-assortment through di-mon mating with a genotype of H. irregulare. This is the first report of a Heterobasidion sp. in L. lyalli, and it is the second report of a natural Heterobasidion hybrid in North America (1). This finding indicates Alpine larch may be a host for both Heterobasidion species, as described for pine stumps in California (1). Thus, this conifer may have provided a substrate for the hybridization and interspecific gene introgression documented to have occurred before stumps were generated in high frequency by modern forestry practices (2).

Ancient Barkpeeled Trees in the Bitterroot Mountains, Montana: Legacies of Native Land use and Implications for their Protection

Culturally modified trees (CMTs) are trees with scars that reflect human utilization of forested ecosystems. Some CMTs can reveal unique knowledge of native cultures and insight to peoples' subsistence and land use in the past, and are mostly to be found in protected areas since they contain very old trees. In this study, we examine attributes and the spatial and temporal distribution of bark-peeled trees, and present forest structure in two remnant ponderosa pine forests (Pinus ponderosa P. & C. Lawson) in western Montana. We also wanted to use an alternative method of dating CMTs and initiate a broader discussion of threats to such trees and needs for sustaining and protecting them. In total, 343 bark-peelings were recorded on 274 living and dead trees. Our results show that only certain trees were selected for harvest. Nearby trees of similar size and age were not used. The age estimation indicates that the bark-peelings were performed from the mid 1600s until the early 1900s. Today the forest at both study areas is generally low in density and all-aged with very old individual trees. They consist of a mosaic of uneven-aged tree groups and individual trees of various ages. We conclude that the abundance and density of bark-peeled trees at the study areas exceed values reported in most other North American studies (formally protected forests included), that the two areas represent different harvest areas for ponderosa pine inner bark, and that CMTs need to be recognized both as ecologically and culturally valuable features of old ponderosa pine forests.

The Fifth Generation: A Nez Perce Tale (review)

Reviewed by: The Fifth Generation: A Nez Perce Tale Loree Westron The Fifth Generation: A Nez Perce Tale. By Linwood Laughy. Kooskia, ID: Mountain Meadow Press, 2009. 258 pages, $23.95. In September of 1805, the Lewis and Clark expedition emerged from the Bitterroot Mountains into what is now North Central Idaho. Half starved from their arduous journey, they were fed and befriended by the local Nez Perce, being the first white men they had encountered. According to an epigraph to Linwood Laughy's first novel, The Fifth Generation: A Nez Perce Tale, Nez Perce oral tradition predicted this meeting with white men coming from the East and stated that it would result in difficult times for the tribe for five generations. Following the story of Isaac Moses, who embodies the fifth generation, the novel weaves together 150 years of history. In alternating chapters, we see the Nez Perce world change utterly, and the heartache of Isaac's family is revealed as they and their community struggle to keep pace. At the center of the story is the spiritual rift created by the missionaries Henry and Eliza Spalding, which divided the Nez Perce in two: Christians who acquiesced to white demands and non-Christian Dreamers who clung to their traditional beliefs. We see the treaties of 1855 and 1863 squeeze the people onto a smaller and smaller reservation as gold prospectors and settlers move into the Nez Perce homeland; we see the war of 1877 and the epic but ultimately futile journey made by the Dreamers; we see the people divided still further, from one another and from the land, by the Dawes Act and the allotment system. In a particularly moving scene, Laughy recreates the heartache of forced assimilation at the Carlisle Indian School: Mary did not dance. The drumming in her soul had been lost along the tracks of the Union Pacific, in the sand hills of Nebraska, in the cemetery behind Hatfield Hall where Carlisle's youthful dead were buried in the Pennsylvania night—brown skin and black hair with names like Rachel, Sarah, Jonah and James. No sound of drums, no sweetgrass smoke, a hurried prayer to a god who spoke neither Nez Perce nor Sioux, Hidatsa nor Crow. (22) It's a familiar story of betrayal and loss, but through Isaac, Laughy presents the potential for renewal. Taking receipt of a government check issued to each of the Nez Perce in recompense for gold extracted illegally [End Page 109] during nineteenth-century gold rushes, Isaac is confronted with a choice: he can drink away the money in the Boots & Saddles Bar or he can reclaim his life. Under the guidance of the aging shaman, Raven Eye, Isaac reconnects with his family's past to discover his true identity, thus becoming the vehicle for carrying the Dreamer traditions into the future. A North Idaho native and historical tour guide, Linwood Laughy knows the landscape and history of the region intimately. Through exquisitely crafted prose, he brings a distant world to life and shows how the past remains with us always, shaping the present and influencing the future. Loree Westron University of Chichester, Chichester, UK Copyright © 2011 Western Literature Association

Decreased winter severity increases viability of a montane frog population

Many proximate causes of global amphibian declines have been well documented, but the role that climate change has played and will play in this crisis remains ambiguous for many species. Breeding phenology and disease outbreaks have been associated with warming temperatures, but, to date, few studies have evaluated effects of climate change on individual vital rates and subsequent population dynamics of amphibians. We evaluated relationships among local climate variables, annual survival and fecundity, and population growth rates from a 9-year demographic study of Columbia spotted frogs (Rana luteiventris) in the Bitterroot Mountains of Montana. We documented an increase in survival and breeding probability as severity of winter decreased. Therefore, a warming climate with less severe winters is likely to promote population viability in this montane frog population. More generally, amphibians and other ectotherms inhabiting alpine or boreal habitats at or near their thermal ecological limits may benefit from the milder winters provided by a warming climate as long as suitable habitats remain intact. A more thorough understanding of how climate change is expected to benefit or harm amphibian populations at different latitudes and elevations is essential for determining the best strategies to conserve viable populations and allow for gene flow and shifts in geographic range.

Small valley glaciers and the effectiveness of the glacial buzzsaw in the northern Basin and Range, USA

The glacial buzzsaw hypothesis suggests that efficient erosion limits topographic elevations in extensively glaciated orogens. Studies to date have largely focussed on regions where large glaciers (tens of kilometres long) have been active. In light of recent studies emphasising the importance of lateral glacial erosion in lowering peaks and ridgelines, we examine the effectiveness of small glaciers in limiting topography under both relatively slow and rapid rock uplift conditions. Four ranges in the northern Basin and Range, Idaho, Montana, and Wyoming, USA, were chosen for this analysis. Estimates of maximum Pleistocene slip rates along normal faults bounding the Beaverhead–Bitterroot Mountains (~ 0.14 mm y − 1 ), Lemhi Range (~ 0.3 mm y − 1 ) and Lost River Range (~ 0.3 mm y − 1 ) are an order of magnitude lower than those on the Teton Fault (~ 2 mm y − 1 ). We compare the distribution of glacial erosion (estimated from cirque floor elevations and last glacial maximum (LGM) equilibrium line altitude (ELA) reconstructions) and fault slip rate with three metrics of topography in each range: the along-strike maximum elevation swath profile, hypsometry, and slope-elevation profiles. In the slowly uplifting Beaverhead–Bitterroot Mountains, and Lemhi and Lost River Ranges, trends in maximum elevation parallel ELAs, independent of variations in fault slip rate. Maximum elevations are offset ~ 500 m from LGM ELAs in the Lost River Range, Lemhi Range, and northern Beaverhead–Bitterroot Mountains, and by ~ 350 m in the southern Beaverhead–Bitterroot Mountains, where glacial extents were less. The offset between maximum topography and mean Quaternary ELAs, inferred from cirque floor elevations, is ~ 350 m in the Lost River and Lemhi Ranges, and 200–250 m in the Beaverhead–Bitterroot Mountains. Additionally, slope-elevation profiles are flattened and hypsometry profiles show a peak in surface areas close to the ELA in the Lemhi Range and Beaverhead–Bitterroot Mountains, suggesting that small glaciers efficiently limit topography. The situation in the Lost River Range is less clear as a glacial signature is not apparent in either slope-elevation profiles or the hypsometry. In the rapidly uplifting Teton Range, the distribution of ELAs appears superficially to correspond to maximum topography, hypsometry, and slope-elevations profiles, with regression lines on maximum elevations offset by ~ 700 and ~ 350 m from the LGM and mean Quaternary ELA respectively. However, Grand Teton and Mt. Moran represent high-elevation “Teflon Peaks” that appear impervious to glacial erosion, formed in the hard crystalline bedrock at the core of the range. Glacier size and drainage density, rock uplift rate, and bedrock lithology are all important considerations when assessing the ability of glaciers to limit mountain range topography. In the northern Basin and Range, it is only under exceptional circumstances in the Teton Range that small glaciers appear to be incapable of imposing a fully efficient glacial buzzsaw, emphasising that high peaks represent an important caveat to the glacial buzzsaw hypothesis.

The influence of white pine blister rust on seed dispersal in whitebark pine

We tested the hypotheses that white pine blister rust ( Cronartium ribicola J.C. Fisch.) damage in whitebark pine ( Pinus albicaulis Engelm.) stands leads to reduced (1) seed cone density, (2) predispersal seed survival, and (3) likelihood of Clark’s Nutcracker ( Nucifraga columbiana (Wilson, 1811)) seed dispersal. We gathered data from two sets of paired forest sites in the Bitterroot Mountains of eastern Idaho and western Montana that were similar in topography, canopy structure, tree species composition, and successional stage, but differed in rust infection level, crown kill, and tree mortality. We counted initial (mid-July) and final (late August) seed cones, observed vertebrate seed predator activity, and documented nutcracker seed dispersal in study sites in 2001 and 2002. High-rust sites had higher rates of seed predation relative to cone abundance, lower predispersal seed survival, and fewer observations of nutcracker seed dispersal than paired low-rust sites. These findings suggest that as blister-rust-induced damage increases within stands in the Bitterroot Mountains, the likelihood of nutcracker seed dispersal decreases. We propose that whitebark pine in heavily rust-damaged forests may not self-regenerate and would therefore require planting of seeds or seedlings from genetically rust-resistant trees.

Ten-year responses of ponderosa pine growth, vigor, and recruitment to restoration treatments in the Bitterroot Mountains, Montana, USA

Little is known about ponderosa pine forest ecosystem responses to restoration practices in the Northern Rocky Mountains, USA. In this study, restoration treatments aimed at approximating historical forest structure and disturbances included modified single-tree selection cutting, with and without prescribed burning. We compared the effectiveness of restoration treatments on growth, vigor, and composition of recruitment responses with untreated controls. We used a randomized block design to detect treatment differences in mean individual tree basal area increment (BAInc10), growth efficiency (GE), and recruitment abundance between two restoration treatments (Cut-only and Cut-burn) and a Control. We further examined treatment effects by tree age-class (Young, Mature, Presettlement) using a spatial ANOVA model that incorporates the spatial autocorrelation among trees within experimental units. Ten years after implementing restoration treatments, mean individual tree BAInc10 and GE were significantly higher for treated units relative to Control units; all three age-classes benefited similarly from restoration treatments relative to the Control, with the greatest response in the Cut-only and moderate response in the Cut-burn. When treated units were compared, Cut-burn negatively affected BAInc10 and GE relative to Cut-only. Presettlement trees responded positively to treatment relative to the Control, particularly for BAInc10, demonstrating the potential of these old trees to respond to reduced competition. The Cut-burn treatment, in contrast, negatively affected the BAInc10 and GE response of postsettlement trees when compared to Cut-only. Restoration treatments did not reduce the amount of Douglas-fir recruits. In addition, the recruitment of both ponderosa pine and Douglas-fir species was associated with the proximate cover of woody debris in Cut-only and Control treatments. Finally, special consideration needs to be taken for spring Cut-burn treatments, which appeared to dampen growth and vigor, relative to Cut-only, particularly for Young and Mature trees, and increased recruitment of ponderosa pine and particularly Douglas-fir.

Describing a New Environment: Lewis and Clark and Enlightenment Science in the Columbia River Basin

KristenPeterson,photographer (detail),courtesy Missouri Historical Society The Lewis and ClarkNational BicentennialExhibition is currently at the Missouri Historical SocietyinSt.Louis.TheOregonHistorical Society will hosttheexhibit from November 2005 throughMarch 2006 ? its only venue on theWest Coast. WilliamL. Lang Describing a New Environment LewisandHark andEnlightenment ScienceintheColumbia RiverBasin N august 1805, the Corps of Discovery topped the Continental Divide after a laborious journey up theMissouri River ? more than thirty-one hundred miles, byWilliam Clark's later reckon ing, from their departure point at the river'smouth.1 Tracing the Missouri to its sources marked the achievement of a major objective, but the view Meriwether Lewis took in as he looked west from Lemhi Pass startled him. "After refreshing ourselves," Lewis wrote on August 12, "we proceeded on to the top of the dividing ridge from which I discovered immence ranges of high mountains still to the West of us with their tops partially covered with snow." That view dashed the imagined geography Lewis and Clark had carried with them since leaving FortMandan inApril. They had expected thewest side of the divide tomimic the east side and to offer an unencumbered descent to the Columbia River and the Pacific Ocean. Looking into the sawtoothed Bitterroot Mountains put Lewis in a position he had endured before when the geography had surprised him and forced new decisions. As they had throughout the expedition, the co-leaders pondered their options, knowing that their destination might be more distant but also knowing that reaching itwas compelling and essential to the success of theirmission.2 The scene is familiar to students of the great exploration led byMeri wether Lewis andWilliam Clark into theAmerican West. It is amoment of adventure and challenge, the essence of the Lewis and Clark story,a saga of exploration that rivals John Wesley Powell's float of theGrand Canyon, JohnGlenn's orbit of the Earth, and Neil Armstrong's walk on themoon. 360 OHQ vol. 105, no. 3 ? 2004 Oregon Historical Society Ewell Sale StewartLibrary, The Academy ofNatural Sciences of Philadelphia ?? BPECOtL^ These specimens o/Mahonia aquifolium ? also known as Berber?s aquifolium, or shiny Oregon grape ? which Lewis collected at theGreat Falls of theColumbia, are part of the Lewis and Clark Herbarium. Lang, Describing a New Environment 361 Most Americans have been told the Lewis and Clark story as an adventure, and ithas been thatway from the first telling of their experiences byNicho lasBiddle in History ofthe ExpeditionunderCaptains Lewis andClark in 1814 to Stephen Ambrose's enormously successful Undaunted Courage in 1996. The expedition has been a story of accomplishment, often setwithin a patriotic context. Itsbackground, proximate causes, and stated objectives, however, are not well known to the general public. Even less known and understood are the exploration's scientific purposes. Although President Thomas Jefferson created the expedition for nationalistic, geopolitical, and economic reasons, he also had science inmind when he sent Lewis and Clark to the West two centuries ago.3 Science in the eighteenth century had developed principally as an in vestigation of natural phenomena and the diversity of life.Enlightenment scientists, historian Donald Worster has argued, pursued the description of nature while they also investigated the apparent harmony resident in the natural world. Lewis and Clark carried these Enlightenment scientific interests and assumptions with them as they explored theColumbia River Basin, and their journals disclose their comprehension of the environment as natural and human ecology. They saw the lands west of the divide, in part, as scientists, and as scientists they documented the relationships between people and environment for the scientific enterprise.4 A case can be made that Jefferson's interest in theAmerican West grew out of his fascination with the natural world and his pursuit of scientific information about regions west of theAppalachian Mountains. He had science on his mind in 1783, just after Britain and theUnited States signed the peace treaty,when he first articulated the idea for a western explora tion and tried to enlist George Rogers Clark as expedition leader. Clark was one of the young nation's most experienced soldiers, a veteran of Revolutionary War campaigns on the western frontier, an exponent of western expansion, and someone interested in scientific discovery. Writing to Clark inDecember...

Low-temperature thermochronological record of exhumation of the Bitterroot metamorphic core complex, northern Cordilleran Orogen

The Bitterroot metamorphic core complex is an exhumed, mid-crustal, plutonic–metamorphic complex that formed during crustal thickening and subsequent extension in the hinterland of the North American Cordilleran Orogen, in the northern Idaho batholith region. Extension was accommodated mainly on the Bitterroot mylonite zone, a 500–1500-m-thick shear zone that deforms granitic intrusive rocks as young as 53–52 Ma, as well as older high-grade metamorphic rocks and plutons. Exhumation of the core complex, in Eocene time, is marked in the shear zone by the transition from amphibolite-facies mylonitization, to greenschist-facies mylonitization, chloritic brecciation, to brittle faulting that progressed from shallower crustal levels in the west to deeper crustal levels in the east from ca. 53 –30 Ma based on U–Pb, Ar–Ar, and fission-track data. Apatite and zircon fission-track data record the lower-temperature part of the exhumation history and help define when the shear zone became inactive, as well as the transition from rapid, core complex-style extension to slower basin-and-range-style extension. They indicate that the western part of the complex was exhumed to within 1–2 km of the surface by ∼48–45 Ma, while the eastern part of the complex was still at amphibolite-facies conditions and that the eastern part of the complex was not exhumed below ∼60 °C until after 30 Ma. Younger apatite fission-track ages (≤26 Ma) on the eastern range front of the Bitterroot Mountains suggest that the present topographic expression of the mylonite front was due to Miocene high-angle faulting and widening of the Bitterroot Valley.

Genetic Differentiation among Long-Toed Salamander (Ambystoma macrodactylum) Populations

We examined the genetic population structure of Long-Toed Salamanders (Ambystoma macrodactylum) from the Bitterroot Mountains of Idaho and Montana to better understand their evolutionary history and genetic population structure. Populations show high levels of within-population genetic variation at six polymorphic allozyme loci (H̄s = 0.09 for all 18 loci examined; range 0.04–0.14). There is very little divergence among populations within basins, suggesting panmixia within basins. In contrast, genetic differentiation among all populations is high (Gst = 0.30). We used computer simulations to examine population structures that could have led to the observed distribution of genetic variation, assuming selective neutrality of the allozymes. To test the assumption of selective neutrality of the markers used in this study, we compared the observed divergence among the allozymes to that expected from simulations of independently segregating and selectively neutral markers. The observed genetic divergence among populations is compatible with that expected for neutral genetic markers sampled from panmictic populations within basins that exchange less than one migrant among basins each generation.

Colonization of high-elevation lakes by long-toed salamanders (Ambystoma macrodactylum) after the extinction of introduced trout populations

We surveyed high-elevation lakes for long-toed salamander (Ambystoma macrodactylum) larvae and trout in the northern Bitterroot Mountains of Montana, U.S.A., in 1978, 1997, and 1998. Our objectives were to (i) test whether trout exclude salamander populations; (ii) determine whether lakes in which trout have gone extinct have since been colonized by salamanders; and (iii) estimate the rates of population extinction and colonization in lakes never stocked with trout. In agreement with previous work on the interactions between trout and long-toed salamanders, trout effectively excluded salamander populations from lakes. Somewhat surprisingly, however, salamanders managed to colonize lakes after the extinction of trout populations despite evidence of low levels of interpopulation dispersal in these salamander populations. In lakes never stocked with trout there was no evidence of a decline in salamander populations; 2 of these lakes were colonized and no populations went extinct.

Characterization of an endosymbiont infecting wood ticks, Dermacentor andersoni, as a member of the genus Francisella.

A microorganism (Dermacantor andersoni symbiont [DAS]) infecting Rocky Mountain wood ticks (D. andersoni) collected in the Bitterroot Mountains of western Montana was characterized as an endosymbiont belonging to the genus Francisella. Previously described as Wolbachia like, the organism's DNA was amplified from both naturally infected tick ovarial tissues and Vero cell cultures by PCR assay with primer sets derived from eubacterial 16S ribosomal DNA (rDNA) and Francisella membrane protein genes. The 16S rDNA gene sequence of the DAS was most similar (95.4%) to that of Francisella tularensis subsp. tularensis. Through a combination of Giménez staining, PCR assay, and restriction fragment length polymorphism analysis, 102 of 108 female ticks collected from 1992 to 1996 were infected. Transovarial transmission to female progeny was 95.6%, but we found no evidence of horizontal transmission.

Timeless Journals: Reading Lewis and Clark with Nicholas Biddle's Help

The journals of the Lewis and Clark expedition describe the continental crossing of the first United States Exploring Expedition between 1804 and 1806.1 Under the command of Meriwether Lewis and William Clark, the explorers followed the Missouri to its source in Montana. They crossed the continental divide at Lemhi Pass hoping to find a short portage to the headwaters of the Columbia River. After the mysterious Wilderness Passage proved to be an illusion, they struggled through the Bitterroot Mountains in northern Idaho and then continued

DNA typing of rickettsiae in naturally infected ticks using a polymerase chain reaction/restriction fragment length polymorphism system.

We used the polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) rickettsial typing system of Regnery and others to rapidly identify rickettsiae in naturally infected ticks. Unlike previously described methods, our PCR assays type rickettsiae directly from tick tissues without first isolating the organisms. We collected 226 adult Dermacentor andersoni ticks in the Bitterroot Mountains of western Montana and analyzed them for possible rickettsial infection by hemolymph test using the Gimenez stain. Thirteen (5.8%) of these ticks were positive by hemolymph test and selected for further analysis using the above PCR/RFLP typing system. The PCR assays performed using the first primer set (RpCS) resulted in amplification of fragments of the predicted size from nine of the 13 hemolymph test-positive tick samples. Only four of these nine tick samples were also positive in similar PCR assays performed with a second primer set (Rr190) that is presumed to be spotted fever group specific. The RFLP analyses of material amplified from these four ticks indicated they were infected with Rickettsia rickettsii (one sample) and R. rhipicephali (three samples). The PCR/RFLP analyses of the five PCR-positive tick samples that were positive only in assays performed with the RpCS primer set indicated that these ticks were infected with R. bellii. The remaining four of 13 hemolymph test-positive tick samples gave negative PCR results with both the RpCS and Rr190 primer sets. Infected hemocytes from these PCR-negative ticks contained organisms of distinctive bacillary morphology that appeared similar to those described previously as long forms, and it is possible that these organisms belong to a genus other than Rickettsia. We also examined established laboratory isolates of tick-borne rickettsiae from different regions of North America to determine whether this typing system produces consistent results. Multiple isolates of R. montana (nine isolates), R. bellii (five isolates), R. rickettsii (Hlp-like) (four isolates), and R. canada (two isolates) were tested and no significant variations in PCR/RFLP patterns were observed between members of the same serotypes. However, among the five isolates of R. rhipicephali tested, two slightly different RFLP patterns were noted. Our results suggest that this PCR/RFLP typing scheme has wide applicability for identifying rickettsiae directly from D. andersoni or D. variabilis tick tissues.

Age and Condition of Deer Killed by Predators and Automobiles

We evaluated the condition of mule deer (Odocoileus hemionus) and white-tailed deer (0. virginianus) killed by mountain lions (Felis concolor), coyotes (Canis latrans), and automobiles from December through March, 1969-81 in western Montana. Predators killed prime-aged animals and automobiles killed (G = 41.4, P < 0.001) more fawns and old-aged animals. Fifty-three deer (90%) killed by automobiles were in poor condition, but only 2 (7%) deer killed by predators were in poor condition. Predator selectivity could not be inferred from the sample of deer killed by automobiles. J. WILDL. MANAGE. 52(2):316-320 The influence of predation on young and old animals and animals in poor condition is important in population dynamics. To assess selectivity, standing age structure or herd condition from a representative sample of the herd is needed. In studies that do not involve capturing and marking herbivores, hunter kills (Fritts and Mech 1981) and accidental kills (e.g., automobiles: Pimlott et al. [1969], Franzmann and Arneson [1976]) are commonly used to obtain data. Although the potential for bias in a sample of hunter-killed animals is often recognized (Frazer 1976, McCullough 1979, Downing 1980), less attention has been paid to possible biases in accidental kills. We present age structures and condition of deer killed by predators and by automobiles in western Montana, and examine possible biases in each sample. STUDY AREA Predator kills were found on mule deer winter ranges in the foothills of the Bitterroot Mountains and white-tailed deer ranges of the Swan and Clearwater valleys in western Montana. Automobile kills were collected from major highways around Missoula, Montana. Mule deer winter ranges were primarily on south-facing slopes. These areas support a foothills bunchgrass habitat interspersed with Douglas-fir (Pseudotsuga menziesii)-ninebark (Physocarpus malvaceus) and ponderosa pine (Pinus ponderosa)-savannah vegetation types (Pfister et al. 1977). White-tailed deer ranges were mostly in oldgrowth forests. The Clearwater and Swan rivers, interspersed with lakes, generally divide the This content downloaded from 157.55.39.223 on Wed, 24 Aug 2016 05:11:18 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 52(2):1988 CONDITION OF DEER * O'Gara and Harris 317 study area, and level lowlands extend to the east and west from them to meet an east-facing slope on the western edge and a west-facing slope on the eastern edge of the study area. Bunchgrass habitats of the ponderosa pine series are present in limited portions of the study area. All but 4 of the 15 habitats within the Douglas-fir series described by Pfister et al. (1977) are distributed in a mosaic pattern within the study area. The major highways where deer killed by automobiles were collected ran along rivers below mule deer winter ranges and through white-tailed deer ranges and agricultural lands.