Montana Range Research Articles

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Fluvial Arctic Grayling and the Limits of Conservation

The Arctic grayling (Thymallus arcticus), a member of the salmon family, historically inhabited only two areas within the coterminous United States: parts of Michigan and the upper Missouri River system, primarily in Montana. The species vanished from Michigan by the mid-1930s and the fluvial variety persists in but a tiny fraction of its range in Montana. Focusing on Montana’s Big Hole River (the last place in the Lower 48 where native fluvial grayling survive) and Michigan’s Au Sable River (once a prominent grayling fishery and today a renowned trout stream), this article examines how a combination of capitalist endeavors and climate change contributed to the fish’s decline and hampered efforts to preserve and reintroduce grayling populations. As overfishing, shifts in land use, and introductions of non-native salmonids visibly eroded the grayling populations of both states by the early twentieth century, government agencies and sportsmen’s groups counted on hatchery work to save the species. Although conservationists had successfully created and diversified recreational fisheries by propagating and stocking other species, this method bore little fruit when applied to fluvial grayling. Undercut by the profound transformation of waterways, fluvial grayling conservation and restoration efforts offer a humbling case study of the limitations of science and human agency.

Feral horses are associated with a decline in a rare semi-arid grassland plant

Physaria lesicii (Rollins) O'Kane & Al-Shehbaz is a globally rare plant known from only three populations in the Pryor Mountain Wild Horse Range in Montana, USA, an area subjected to grazing by feral horses for at least 100 years. The purpose of this study was to determine effects of trampling by feral horses on this rare plant. I measured density of P. lesicii plants in 33 paired on- and off-trail sample plots at the one of three known populations in a semi-arid habitat where horse trailing was prevalent. I also determined the strength of the association between the presence of presumed nurse plants and P. lesicii at two different populations. Density of P. lesicii plants was approximately four times as great in grassland than on adjacent trails. There was a significant association between the presence of potential nurse plants (canopy cover) and P. lesicii density only at the lower, presumably more stressful site. These results indicate that feral horse trampling has resulted in a significant decline in the number of P. lesicii plants where horses are most abundant and suggest that loss of nurse plants may partly explain this decline.

Northeastern Montana range pastures maintaining distinct American bison herds yield different trace metal availability and intestinal parasite infections in the American Bison on the Fort Peck Indian Reservation

BackgroundThe Fort Peck Reservation tribes maintain two distinct bison herds on different pastures in Montana which includes a cultural herd (purebred) and a business herd (contains beef genes). The different pastures housing the herds have different Animal Unit Months (AMU) ratings (a measurement of forage/acre per adult animal) with the cultural herd pasture having a higher rating. With the limited grazing opportunities, it has been discovered that many of these bison have serious health problems related to malnutrition which can cause lower birth rates. Previous studies indicate metals such as copper (Cu) and zinc (Zn) are necessary for proper health and birthrates. In addition, poor calving rates in apparently healthy bison with adequate protein in diet might simply be from the different metal deficiencies.HypothesisDecreased absorption of Cu and Zn are due to increased absorption of selenium and molybdenum. These deficiencies along with parasitic infections are causing health problems both bison herds on the Fort Peck Reservation.MethodsWe successively isolated liver and fecal samples from euthanized bison to test for toxic and essential trace minerals, and to probe for present parasites in the gastrointestinal tracts. Ova were counted using light microscopes from intestinal fecal matter obtained from the bison.ResultsMineral imbalances were detected as elevated molybdenum (Mo) in both herds. Elevated Mo can deplete liver copper (Cu). Deficient levels of Cu, manganese (Mn) and Zn were evident in both herds. On average cultural animals had Cu levels on of 7.75 ppm, well below the suggested range of 75 ppm while the business herd liver Cu content was averaged to be even lower at 4.33 ppm. Additionally, Mn was found to be deficient in the cultural herd (2.1 ppm where 3.0 ppm is normal) but not in the business herd. Zn was deficient in both herds at 28 ppm where 100 ppm is normal. Also, we determined that bison in both herds were either free of internal parasites or had low burdens of infestation. Seven business herd and 15 cultural herd fecal present in the cultural herd, none in the business herd. We believe health problems from malnutrition contribute to decreased weights and birthrates of the bison on the Fort Peck Indian Reservation samples were analyzed. The business herd had samples that exhibited undetectable ova or parasites per gram of feces while the cultural herd samples had low levels of Strongyle type ova (0.4–7.78 ova/gram of feces). Three of the cultural herd samples in additionally had Trichuris sp. (0.4 ova/gram), Nematodirus (0.2–0.67 ova/gram), and/or Coccidia (0.6 ova/gram).ConclusionsMalabsorption of nutrients is caused by increased absorption of selenium and molybdenum but not infections from parasites in the Bison digestive tract.Support or Funding InformationFunded by the USDA

Methods for monitoring alpine plant phenology: a pilot study in the Line Creek Plateau Research Natural Area, USA

Alpine plant phenological traits are studied and several hypotheses about their latitudinal variation are tested within a comparative research project, which is being conducted on groups of plant species for which relationships are inferred from available phylogenies. The study sites for this project are located in tropical Ecuador, semitropical Bolivia and the temperate Rocky Mountains in the USA. Several temperate alpine species occur near the Rocky Mountains Field Station in Colorado and large populations of three alpine target species (Caltha leptosepala, Castilleja pulchella, Gentiana algida) were found at the Line Creek Plateau Research Natural Area, in the Beartooth Range in Montana. This location was initially investigated in August 2018 to choose the study site and test a methodology for collecting plant trait data. This study site, the target plant species and the results of a preliminary study, together with recommendations for the full season monitoring, are discussed in this paper.

Structural controls of fracture orientations, intensity, and connectivity, Teton anticline, Sawtooth Range, Montana

The Teton anticline is a multiple hinge anticline containing fractured Mississippian–Devonian carbonates in the frontal part of the Sawtooth Range in Montana. The structure serves as a good surface analog for fracture patterns and connectivities within subsurface-folded carbonate reservoirs. The primary fracture sets are longitudinal and transverse relative to the axis of the fold, although two additional oblique sets are also present. The length and density of the longitudinal fracture sets are strongly controlled by position relative to multiple hinges. The transverse fractures are related to changes in fold plunge and exhibit less variation in fracture density. Fracture connectivity is dependent on the number of fracture sets, their orientations and dispersions, and the densities of the fracture sets. The connectivity is measured using two parameters: the fractional connected area (FCA), which represents the fraction of the total sample area that is connected by fractures, and the distribution of clusters of different sizes in any given area. Because the longitudinal fractures represent the dominant fracture set and also show the most variation with structural position, the fracture connectivity, as measured by both the FCAs and the distribution of cluster sizes, is greater in the vicinity of the fold hinges. The results and approaches used in the study have some important implications for subsurface-folded fractured carbonate reservoirs. The analysis of sparsely distributed fracture data from wells must be integrated with an understanding of the controls of the macroscopic structure on fracture parameters to effectively simulate fracture patterns and connectivities around subsurface structures.

Columbia Mountain landslide: late-glacial emplacement and indications of future failure, Northwestern Montana, USA

The well preserved and undissected Columbia Mountain landslide, which is undergoing suburban development, was studied to estimate the timing and processes of emplacement. The landslide moved westward from a bedrock interfluve of the northern Swan Range in Montana, USA onto the deglaciated floor of the Flathead Valley. The landslide covers an area of about 2 km 2, has a toe-to-crown height of 1100 m, a total length of 3430 m, a thickness of between 3 and 75 m, and an approximate volume of 40 million m 3. Deposits and landforms define three portions of the landslide; from the toe to the head they are: (i) clast-rich diamictons made up of gravel-sized angular rock fragments with arcuate transverse ridges at the surface; (ii) silty and sandy deposits resting on diamictons in an internally drained depression behind the ridges; and (iii) diamictons containing angular and subangular pebble-to block-sized clasts (some of which are glacially striated) in an area of lumpy topography between the depression and the head of the landslide. Drilling data suggest the diamictons cover block-to-slab-sized bedrock clasts that resulted from an initial stage of the failure. The landslide moved along a surface that developed at a high angle to the NE-dipping, thinly bedded metasediments of the Proterozoic Belt Supergroup. The exposed slope of the main scarp dips 30–37°W. A hypothetical initial rotational failure of the lower part of a bedrock interfluve may have transported bedrock clasts into the valley. The morphology and deposits at the surface of the landslide indicate deposition by a rock avalanche (sturzstrom) derived from a second stage of failure along the upper part of the scarp. The toe of the Columbia Mountain landslide is convex-west in planview, except where it was deflected around areas now occupied by glacial kettles on the north and south margins. Landsliding, therefore, occurred during deglaciation of the valley while ice still filled the present-day kettles. Available chronostratigraphy suggests that the ~1-km thick glacier in the region melted before 12,000 14C years BP—within 3000 years of the last glacial maximum. Deglaciation and hillslope failure are likely causally linked. Failure of the faceted interfluve was likely due tensile fracturing of bedrock along a bedding-normal joint set shortly after glacial retreat from the hillslope. Open surficial tension fractures and grabens in the Swan Range are limited to an area above the crown of the landslide. Movement across these features suggests that extensional flow of bedrock (sackung) is occurring in what remains of the ridge that failed in the Columbia Mountain landslide. The fractures and grabens likely were initiated during failure, but their morphologies suggest active extension across some grabens. Continued movement of bedrock above the crown may result in future mass movements from above the previous landslide scarp. Landslides sourced from bedrock above the scarp of the late-glacial Columbia Mountain landslide, which could potentially be triggered by earthquakes, are geologic hazards in the region.

Tamarisk growth at the northern margin of its naturalized range in Montana, USA

Tamarisk (Tamarix spp.), an introduced shrub or small tree, has invaded riparian areas throughout the western United States. Tamarisk invasion has been studied extensively in the Southwest, but there is little information on its performance at the northern margin of its naturalized range. We measured the canopy cover, density, height and age of tamarisk and plains cottonwood (Populus deltoides) in 50 plots at 25 sites along the Bighorn, Powder, and Yellowstone rivers in southeast Montana near the northern edge of tamarisk’s western North American range. Tamarisk commonly formed thickets on open, low terraces and along over-flow channels but was less dense beneath a cottonwood canopy. Tamarisk stems routinely died back to the ground, and the oldest live stems were generally much younger than the plants. Tamarisk 30 to 40 years old in our study area usually attained heights of only 4 m or less. Height and number of live stems of tamarisk plants were 16% and 44% lower respectively under a tall cottonwood canopy. Cottonwood grows faster than tamarisk, eventually shading it and causing its decline. We believe that tamarisk will be only an understory shrub in most eastern Montana riparian forests, declining as cottonwoods form a closed canopy. Minimizing the spread of tamarisk in riparian areas in Montana can best be accomplished by managing for cottonwood.

Influence of social dominance rank on diet quality of pronghorn females

The relationship between social dominance rank and diet quality was examined in pronghorn (Antilocapra americana) females at the National Bison Range in Montana. Rank was ascertained by observation of agonistic interactions between study animals. Diet quality of the same individuals was quantified by measuring the concentration of the chemical indicator of forage quality, 2, 6 diaminopimelic acid (DAPA) present in feces. A significant, quadratic relationship was found in which high-ranked and low-ranked females showed high levels of DAPA, and middle-ranked females showed low levels of DAPA. This finding indicated that high and low-ranked females acquired better quality diets than middle- ranked females. I discuss possible explanations for this interesting result which, to my knowledge, has not been anticipated in the literature. Key words: DAPA, diet quality, dominance rank, pronghorn. [Behav Ecol 12:177–181 (2001)]

Reproductive Synchrony in Brucellosis-Exposed Bison in the Southern Greater Yellowstone Ecosystem and in Noninfected Populations

Shooting of bison (Bison bison) in the Greater Yellowstone Ecosystem is a highly polarized, emo- tional issue because native ungulates exposed to brucellosis (Brucella abortus) may infect cattle when they dis- perse or migrate beyond protected reserves. Both bison and elk (Cervus elaphus) carry brucellosis, a disease that causes abortion in livestock and is often transmitted through contact with expelled fetuses or birth mem- branes andfluids. If Brucella-infected bison experience a prolongedperiod of birth, cattle in areas of sympatry will have increased susceptibility to disease. We tested the hypothesis that reproductive synchrony differs be- tween Brucella-free and Brucella-infected bison by contrasting patterns between the Brucella-exposed bison population (in Jackson Hole, Wyoming) within the southern Greater Yellowstone Ecosystem with three non- exposed populations (National Bison Range in Montana, and Wind Cave and Badlands National Parks in South Dakota) that inhabit prairies. Populations averaged 42 births per site per year. Fifty percent of all the births occurred within 1 month, and 95% within 61 days at three sites. It took 89 days for 95% of the births to occur at the noninfected Badlands site. Multiple comparison of regression slopes of the relationship between birth synchrony and the cumulative proportion of total births revealed interpopulation differences (p < 0.01), but the brucellosis-exposed population did not exhibit a parturition period different from that of the nondiseased populations. These among-population similarities suggest that reproductive synchrony is not protracted in Brucella-infected bison. Although Brucella transmission from bison to cattle occurs experimen- tally, captive densities during testing exceeded the mean for the Greater Yellowstone Ecosystem by about 1500 times, and that in 10 noninfected populations by more than 100 times. Although mean density can be mis- leading as a surrogate for the potential transmission of disease from bison to cattle, bison densities have not approached those reportedfor disease transmission. Among the ecologicalfactors that may affect the spread of brucellosisfrom bison to cattle in the southern Yellowstone region, two stand out: (1) access to high-quality food, perhaps because animals in superior physiological condition tend to exhibit tighter reproductive syn- chrony and (2) incidence of disease in elk. The timing of parturition in bison is neither a simnple process nor is it likely to be based on responses to a single variable. A potentially fertile area for future investigation will concern relationships among food, reproductive synchrony, and spatial-temporal components of bison, elk, and cattle distribution.

Kinematic history of a foreland uplift from Paleocene synorogenic conglomerate, Beartooth Range, Wyoming and Montana

An integrated structural, sedimentological, and provenance study of the upper Paleocene Beartooth Conglomerate along the eastern flank of the Beartooth Range in Montana and Wyoming yields new information about Laramide tectonics in the northern Rocky Mountain foreland and has implications for models of fault-propagation folding and the development of synorogenic basins in thrust-faulted terranes. During the Laramide orogeny, the Beartooth Conglomerate was deposited by alluvial fans and a coarse braided fluvial system along the eastern flank of the range in response to displacement on the Beartooth fault, a 30°-35° west-dipping thrust fault that places Precambrian rocks on Paleozoic and Mesozoic cover rocks. Displacement along the Beartooth fault produced a large fault-propagation fold (Berg's fold-thrust) that eventually was transected by the fault along the entire eastern flank of the range. Lithologic provenance modeling indicates that the Beartooth Conglomerate was produced by unroofing of the Upper Cretaceous through Precambrian section of the eastern Beartooth Range. The model results indicate that source-area relief during deposition of the lower part of the Beartooth Conglomerate was relatively low (∼600 m) while the soft, mudstone-dominated Upper Cretaceous part of the source section was being eroded from the crest of the uplift. Coarse, alluvial-fan accumulation commenced when resistant Paleozoic carbonate and quartz-arenitic rocks were exposed and source-area relief increased to ∼1,400 m. Relief steadily diminished thenceforth to ∼600-800 m, as the upper part of the source section was eroded from the Beartooth Range, leaving only a resistant carapace of Paleozoic carbonate rocks and Precambrian crystalline rocks. Source-area relief was controlled both by bedrock composition of the source terrane and by individual episodes of uplift. Like many thrust-derived conglomerates, the Beartooth Conglomerate contains intraformational, syndepositional folds, faults, and angular unconformities that can be used with provenance modeling to define the kinematics of uplift during conglomerate deposition. By utilizing the results of our provenance modeling and the orientations of the basal and intraformational angular unconformities, we have been able to retrodeform stepwise an area-balanced cross section through the eastern Beartooth uplift. Retrodeformation of the cross section indicates that 3.8 km of uplift occurred before deposition of the oldest part of the proximal Beartooth Conglomerate. Further uplift of ∼1.7 km and total horizontal shortening of ∼3.7 km accompanied ∼1.3 km of displacement on the Beartooth fault. Cross sections indicate that additional uplift of ∼1 km and horizontal shortening of ∼2 km accompanied displacement on the Line Creek fault. Our data indicate that during the early stages of uplift by fault-propagation folding, sediment derived from the uplift bypassed the proximal realm and was deposited in distal settings. Bypassing occurred because the eventual footwall of the Beartooth fault was uplifted during fault-propagation folding. Viewed from this perspective, the early fine-grained fills of many Laramide basins may owe their existence to a combination of fine-grained source material and sediment bypassing during the early stages of Laramide uplifts.

Coal-bed Methane Potential in Montana

Montana's coal resources are the second largest of the US, with coal underlying approximately 35% of the state. These resources are estimated at 478 billion tons. Associated coal-bed methane resources are estimated to be 14 tcf. The coals of Montana range from Jurassic to early Tertiary in age and from lignite to low-volatile bituminous in rank. Thickness, rank, maceral composition, and proximate and ultimate analyses all vary vertically and laterally. The state contains eight major coal resource areas. A large percentage of Montana's coal consists of the Paleocene Fort Union lignites of eastern Montana, generally considered of too low a rank to contain significant methane resources. Most of the state's other coal deposits are higher in rank and contain many recorded methane shows. During Cretaceous and Tertiary times, regressive-transgressive cycles resulted in numerous coal-bearing sequences. Major marine regressions allowed the formation of large peat swamps followed by transgressions which covered the swamps with impervious marine shales, preventing the already forming methane from escaping. About 75% of Montana's coal is less than 1,000 ft below the ground's surface, making it ideal for methane production. Associated water appears to be fresh, eliminating environmental problems. Pipelines are near to most of the majormore » coal deposits. Exploration for coal-bed methane in Montana is still in its infancy but at this time shows commercial promise.« less

Performance of crosses among Hereford, Angus and Simmental cattle with different levels of Simmental breeding: V. Calf production, milk production and reproduction of three- to eight-year-old dams.

Measures of maternal productivity and reproduction of Hereford (HH), Angus-Hereford (AH), 25% Simmental-75% Hereford (1S3H), 50% Simmental-50% Hereford (1S1H) and 75% Simmental-25% Hereford (3S1H) dams were studied. Half of each dam breed group was bred to Tartentaise and half to Charolais sires to produce 706 calves at weaning from 930 exposures to breeding in a Montana range environment. Data were analyzed according to a model that included the fixed effects of year, dam breed group, dam age, calf sex, calf sire breed, plus appropriate two-way interactions, linear partial regression on calf birth date and random effects of sire within dam breed group (maternal grandsire of the calf) and sire within calf sire breed. Calf sex interacted with calf sire breed for several traits, but interactions were due to changes of magnitude of differences between sexes. There were no significant interactions of dam breed group with other main effects for calf growth traits, except for the interaction with calf sire breed for some calf growth traits. This interaction was due to a change in magnitude; it suggested that larger sire breeds should be matched to larger dam breeds with greater potential for milk production. The only significant interaction for traits that included reproduction of the dam was dam breed group X age of dam. Ranking of dam breed groups depended on age at measurement. Differences among dam breed groups were significant for most traits. Calf weaning weights for HH, AH, 1S3H, 1S1H and 3S1H dams were 211, 223, 227, 237 and 243 kg, respectively; calf weaning weights per cow exposed were 157, 163, 179, 189 and 169 kg; calf weaning weights per unit of dam weight were .40, .41, .43, .44 and .42, respectively. Thus, dam breed groups that weaned the largest calves were not necessarily the most productive under Montana range conditions.

Relationships between [formula omitted][formula omitted] semen culture and various semen and serology parameters

Semen and blood samples from 154 rams from two Montana range flocks (Flock A, vaccinated for Brucella ovis ; Flock B, nonvaccinated) were evaluated to determine the relationship between Brucella ovis ( B. ovis ) semen culture results and various semen and blood parameters. All rams utilized in this study exhibited no palpable ram epididymitis lesions. Thirteen and 25.6% of the rams tested in Flocks A and B, respectively, had positive B. ovis semen cultures. Only age of ram and ram condition scores differed (P<0.05) between flocks. No flock by semen culture interactions were detected (P>0.05) for any of the parameters evaluated. Age of ram, ram condition score, and spermatozoa rate from forward movement were unrelated (P>0.05) to B. ovis culture results. Rams with positive B. ovis semen cultures had lower sperm motility (P<0.05), higher percentage of abnormal spermatozoa cells (P<0.05), higher percentage of spermatozoa head abnormalities (P<0.01), lower percentage of live-normal cells (P<0.05), higher incidence of white blood cells in semen (P<0.01) and higher complement fixation (CF) titers (P<0.01).

Using Sodium Carbonate to Seal Leaky Stock Ponds in Eastern Montana

Mixing sodium carbonate into the top 100 to 150 mm of soil in three farm ponds constructed in calcareous soil in eastern Montana effectively reduced seepage losses for about 3 years following treatment. Seepage rates the first year after treatment were decreased to 20 to 40% of the pretreatment rate, but they were 60 to 100% of the pretreatment rate 4 years after treatment. Efficient livestock utilization of rangeland forage resources requires that stock water be distributed over the grazing area and available in sufficient quantity to last the entire grazing season. In arid and semiarid grazing regions, where natural lakes, ponds, and streams do not provide season-long water supplies, it has become a standard practice to construct artificial water impoundments like dugouts and small dams. The capacity of each constructed pond is usually less than 6,000 m3 and ponds are distributed to provide easy access to water throughout the pasture system. Most water in stock ponds is lost by evaporation and seepage with only a very small fraction actually used by livestock. Various methods have been used to reduce losses by controlling both evaporation and seepage. For reducing evaporation, floating monomolecular films of long-chain, fatty alcohols (Roberts 1958; Roberts 1959; U.S. Bureau of Reclamation 1958), floating barriers of plastic spheres and blocks, and floating films of low melting-point wax (Cooley and Myers 1973; Cooley 1975) have been tested. Floating covers of foamed rubber and low melting point wax have successfully reduced evaporation by as much as 90% on small tanks (1 lm diameter, or smaller), but they have not been used on lakes or ponds. On larger lakes or ponds, monomolecular layers successfully reduce evaporation by only about 20%-primarily because wind action breaks the film and exposes free water to the evaporative processes. Seepage has been reduced with varying degrees of success by installing physical barriers like concrete and asphalt on reservoir soil surfaces (Dedrick 1975); flexible membranes, like sheet plastic and sheet rubber, buried beneath reservoir soil surfaces (Dedrick 1975; Laing 1975); or clay material, like bentonite, placed and compacted on reservoir soil surfaces (Dedrick 1975; Jamison and Thornton 1963; Laing 1975). Disadvantages of these seepage control measures are either the cost of materials and labor for initial installation and maintenance or the mechanical damage caused by weather, frost, and wild and domestic livestock. Author is research hydraulic engineer, U.S. Dep. Agr., Science and Education Administration, Agricultural Research, Northern Plains Soil and Water Research Center, P.O. Box 1109, Sidney, Montana 59270. This research is a contribution from the U.S. Dep. Agr. Science and Education Administration, Agr. Res., in cooperation with the Montana Agr. Exp. Sta. Journal Series No. 691. Manuscript received February 1, 1979. Several researchers (Dedrick 1975; Jamison and Thornton 1963; Laing 1975; Reginato et al. 1968; Reginato et al. 1973) have tried to decrease seepage with soil chemical treatments using various sodium compounds including sodium chloride, sodium carbonate, and sodium polyphosphates. Sodium in these compounds replaces the calcium and magnesium cations on the exchange complex causing the soil aggregates to disperse and the clay colloids to swell, thus sealing soil pores through which water seeps (Nakayama 1966). Sodium carbonate was an effective sealant in Arizona studies, because this salt provided not only sodium cations necessary for soil dispersion but also carbonate anions, which combined with calcium and magnesium and precipitated as insoluble salts (Nakayama 1966; Reginato et al. 1973). Seepage in these study ponds was drastically reduced after initial sodium carbonate treatment, but it gradually increased to an undesirable rate in about 3 years as calcium and magnesium in runoff water replaced sodium applied in the treatment. At this time, seepage was reduced to the immediate post-treatment rate by broadcasting a mixture of sodium carbonate and sodium chloride on the water surface. Seepage rates in stock ponds in eastern Montana range from less than 7 mm/day to more than 30 mm/day. The ponds where seepage exceeds 15 mm/ day generally become dry in late summer or early fall before livestock can efficiently utilize available rangeland forage. A low-cost method of sealing leaky stock would extend the available water supply into the fall and provide an economical opportunity for better forage use. A mail survey of all farm owners and operators in Sheridan County, Montana, provided an estimate of 800 to 900 stock ponds within the county. Nearly two-thirds of the ponds were classified as having poor and fair seepage rates, an indication of the number of ponds in this county alone that might benefit from an effective, low-cost sealing method.

Diurnal variation of plasma testosterone in wild stallions.

Three wild horse stallions from the Pryor Mountain National Wild Horse Range in Montana were captured and blood samples collected over a 24 h period. Androgens were extracted from the plasma, testosterone was isolated by Sephadex LH-20 column chromatography and quantitated by a competitive-protein-binding assay. All three horses exhibited similar qualitative changes in testosterone concentrations during the 24 h, with the nadir occurring at 2300 (1.37 ± 0.75 ng/ml) and a peak at 0800 (3.48 ± 0.12 ng/ml). One of the horses, an eight year old bachelor stallion which has never made an effort to gather a harem since sexual maturity, had a significantly lower (P<0.01) 24 h mean testosterone concentration (1.52 ± 0.89 ng/ml) than either of the two stud stallions (2.68 ± 0.59 ng/ml and 3.20 ± 0.68 ng/ml), both of which have possessed harems and sired colts. It is concluded that all three stallions possessed a diurnal testosterone rhythm. Whether the lower testosterone concentrations in the bachelor stallion are a cause or an effect of sexual disinterest remains unanswered.

Continuous non-therapeutic use of antibacterial drugs in feed and drug resistance of the gram-negative enteric florae of food-producing animals.

Fecal samples from Illinois farm animals and Montana range cattle were examined for the frequency of gram-negative enteric organisms resistant to oxytetracycline, dihydrostreptomycin, or ampicillin. The Illinois farm animals were continually fed rations containing various antibacterial drugs. The Montana range cattle had minimal exposure to antibacterial drugs. The majority of samples from Illinois farm animals demonstrated 10% or more antibiotic-resistant organisms. In contrast, resistant organisms could not be detected in the majority of samples from Montana range cattle. The majority of Escherichia coli isolated from Illinois farm animals was resistant to various antibacterial drugs, whereas less than 1.6% of the isolates from Montana range cattle were resistant to any one of the antibacterial drugs tested.

Winter Food Habits, Range Use, and Home Range of Antelope in Montana

A study of the food habits, range use, and home range of pronghorn antelope (Antilocapra americana) with emphasis on the winter period was conducted in 1966-67 in Montana. Quantitative measurements of canopies and densities of taxa were made in five of the eight vegetation types available to antelope. The sagebrush-grassland type received most of the use by antelope, both in summer and winter. Most winter observations were in vegetation types where sagebrush was common. The winter diet, determined by plant utilization, consisted of 93 percent shrubs, 6 percent forbs, and a minor amount of grass. The diet, determined by analysis of rumen contents, consisted of 78 percent shrubs, 19 percent forbs, and a small amount of grass. Big sagebrush (Artemisia tridentata) provided 45 percent of the antelope food in winter. Results of five summer aerial censuses showed 32 male antelope per 100 females and 74 fawns per 100 females. Poor body condition of antelope and some fawn mortality in winter was possibly related to quality of sagebrush in the diet. Winter home-range size was determined for each of 16 individually marked antelope, three using telemetry. Eight of the marked antelope shifted their home range at least once. A yearling female had a home-range size of 5,574 acres and a yearling male, 4,160 acres. Six adult females had an average home-range size of 2,841 acres; three fawn females, 2,417 acres; and five fawn males, 1,580 acres. Information on the winter food and rangeuse habits of pronghorn antelope in Montana is somewhat limited. Cole (1956) reported the results of a comprehensive study of food and range-use habits with special reference to alfalfa, but data for winter were less comprehensive than for other seasons. Cole and Wilkins (1958) studied food and range use in reference to the effects on production of winter wheat. Martinka (1967) reported on mortality and food habits during a severe winter. Prominent among reports for other states are those of Einarsen (1948) and Buechner (1950) who gave information for Oregon and Texas, respectively. The principal objectives of my study, conducted during the summer of 1966 and winter of 1966-67, were to obtain quantitative data on food habits, range use, and home range of pronghorns in winter to help 1 A joint contribution from Montana State University, Agricultural Experiment Station, Project No. 400, Paper No. 934 Journal Series and the Game Management Division, Project Nos. W-98-R6 and 7, Montana Fish and Game Department. 538 evaluate current management practices (Bayless 1967). An additional parameter of the investigation was concerned with the effects of sagebrush removal on wildlife. The summer period was largely devoted to studies of the vegetation. The use of telemetry in winter greatly aided the study of habitat relationships and behavior. To the following, I wish to extend appreciation for their contributions: D. C. Quimby, Montana State University, for technical supervision and guidance in preparation of the manuscript; R. J. Mackie, formerly with the Montana Department of Fish and Game, for initial project planning; W. E. Booth, Montana State University, for verification of my identification of plant specimens; N. S. Martin, D. Pyrah, T. W. Mussehl, R. R. Knight, and P. Schladweiler, Montana Department of Fish and Game, for assistance during various phases of the study; personnel of the Bureau of Land Management, Lewistown District Office, for their cooperation; and to my wife, Judy, for encouragement and assistance. This content downloaded from 157.55.39.123 on Mon, 18 Jul 2016 05:48:20 UTC All use subject to http://about.jstor.org/terms ANTELOPE WINTER FOOD, RANGE, AND HOME RANGE IN MONTANA * Bayless

Territoriality in Pronghorn Bucks on the National Bison Range, Moiese, Montana

The behavior of seven different mature male pronghorns (Anti-locapra americana) was studied for 102.6 hours during the rut season of 1966 on the National Bison Range in Montana. the bucks were in non-overlapping territories of Viq to Vs square miles. a buck on his territory displayed aggressive behavior to males that looked toward him or exposed the sides of their bodies to him. the bucks defended their areas against yearling bucks in all 131 interactions, and against other adult bucks in 69 of 73 similar encounters.

Effect of Nitrogen and Irrigation on Yield and Botanical Composition1 of Western Montana Range1

SynopsisFertilizer and water treatments were applied to native range for three years. During this time both treatments increased yield but did not affect botanical composition. After two dry years, the residual effects of both treatments changed botanical composition, resulting in reduced yield from water and an increase in undesirable species from fertilizer.