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Research about Yellowstone National Park

Source-linked reports with geographic coverage including Yellowstone National Park.

At least 217 records · Page 12Linked to original sources
USGS1994

Grizzly bear use of army cutworm moths in the Yellowstone Ecosystem

The ecology of alpine aggregations of army cutworm moths ( Euxoa auxiliaris ) and the feeding behavior of grizzly bears ( Ursus arctos horribilis ) at these areas were studied in the Yellowstone ecosystem from 1988 to 1991. Army cutworm moths migrate to mountain regions each summer to feed at night on the nectar of alpine and subalpine flowers, and during the day they seek shelter under various rock formations. Grizzly bears were observed feeding almost exclusively on moths up to 3 months each summer at the 10 moth-aggregation areas we identified. Fifty-one different grizzly bears were observed feeding at 4 of these areas during a single day in August 1991. Army cutworm moths are a preferred source of nutrition for many grizzly bears in the Yellowstone ecosystem and represent a high quality food that is available during hyperphagia.

Idaho, Montana, Wyoming↗
USGS1994

A field-trip guide to Yellowstone National Park, Wyoming, Montana, and Idaho: Volcanic, hydrothermal, and glacial activity in the region

This field-trip guide was originally prepared for the 7th International Symposium on Water/Rock Interaction (WRI-7) held in July 1992 in Park City, Utah. A large and diversified group of earth scientists and accompanying family members participated in this 3 1/2-day field trip that focused on water/rock interactions over widely ranging temperatures and pressures in the Yellowstone/Grand Teton region. Emphasis was placed on the geochemical and hydrologic characteristics of the thermal waters in the major "geyser basins" of Yellowstone National Park. Information specific to the WRI-7 trip about logistics, lodging, and meals has been deleted from the present guide. The scientific content remains mostly unchanged, except for the addition of a glossary, two illustrations, all photographs, and some text previously presented to the field-trip participants in supplementary materials (see appendix A). Most of the geyser basins in Yellowstone National Park are on a high volcanic plateau at elevations of 2,000 to 2,200 m and are surrounded by much higher mountain ranges. In the middle of summer there generally are cool evenings and early mornings and warm afternoons. Visits to the localities described require short walks, mostly on boardwalks, but some are on what may be wet ground. No long, strenuous climbs are required. Expect brief afternoon thunder showers, particularly at Old Faithful. Please remember that the collecting of any kind of sample in a national park is prohibited except by those who have specific sampling permits issued by the National Park Service. Field-trip participants are asked to leave geologic picks and hammers at home or in their luggage while in Yellowstone National Park.

Idaho, Montana, Wyoming↗
USGS1993

Radium isotope geochemistry of thermal waters, Yellowstone National Park, Wyoming, USA

Radium isotope activities ( 226 Ra, 228 Ra, and 224 Ra), chemical compositions, and sulfur isotope ratios in sulfate were determined for water samples from thermal areas in Yellowstone National Park, Wyoming. Activities of 226 Ra in these waters range from <0.2 to 37.9 dpm/kg. Activity ratios of 228 Ra 226 Ra "> 228Ra226Ra range from 0.26 to 14.2, and those of 224 Ra 228 Ra "> 224Ra228Ra range from 0.73 to 3.1. Radium concentrations are inversely correlated with aquifer equilibration temperatures (estimated from dissolved silica concentrations), while[ Ra Ba "> RaBa ] aq and 228 Ra 226 Ra "> 228Ra226Ra activity ratios depend upon U Ba "> UBa and Th U "> ThU ratios in aquifer rocks. Major controls on Ra concentration in Yellowstone thermal waters are inferred to be 1. (1) barite saturation (at Morris Geyser Basin, Mammoth Hot Springs, and other northern areas) and 2. (2) zeolitewater ion exchange (at Upper Geyser Basin). The data are consistent with a model in which 3. (1) radium and barium are supplied to water by bulk dissolution of aquifer rock, and 4. (2) chemical equilibration of water with rock is rapid relative to the 1602 year half-life of 226 Ra. The 228 Ra 226 Ra "> 228Ra226Ra activity ratios of the waters may in some cases reflect surface enrichments of 232 Th and/or may indicate that α-recoil input of 228 Ra is rapid relative to water-rock chemical equilibration. Activity ratios of 224 Ra 228 Ra "> 224Ra228Ra indicate a nearly ubiquitous 224 Ra excess that generally increases with decreasing pH. Near-surface (≤100 m) thermal water flow velocities at Mammoth Hot Springs are estimated from 224 Ra 228 Ra "> 224Ra228Ra variation to be ≥ 1 m h −1 .

Wyoming↗
USGS1993

Population trend of the Yellowstone grizzly bear as estimated from reproductive and survival rates

The trend of the Yellowstone grizzly bear ( Ursus arctos horribilis ) population was estimated using reproductive rates calculated from 22 individual females and survival rates from 400 female bear-years. The point estimate of the rate of increase was 4.6%, with 95% confidence limits of 0 and 9%. Caution in interpreting this result is advised because of possible biases in the population parameter estimates. The main prospects for improving present knowledge of the population trend appear to be further study of possible biases in the parameter estimates, and the continued use of radiotelemetry to increase the number of samples on which the estimates are based.

Idaho, Montana, Wyoming↗
USGS1993

Potential ungulate prey for Gray Wolves

Data were gathered for six ungulate species that reside in or near Yellowstone National Park. If gray wolves ( Canis lupus ) are reintroduced into the Yellowstone area, their avoidance of human activities or their management by human may determine their range. Therefore, the area of wolf occupation cannot be predicted now. We restricted our analysis to Yellowstone National Park and to the adjacent national forest wilderness areas. We included mostly ungulate herds that summer inside or adjacent to the park and that would probably be affected by wolves. Our wolf study area includes Yellowstone National Park and adjacent wilderness areas most likely to be occupied by wolves. We reviewed publications, park records, survey reports, and state fish and game surveys and reports for statistics on ungulate populations. These data [provide an overview of ungulate populations and harvests. Each ungulate herd is described in detail. We restricted our analysis to 1980-89, because population surveys were more complete during that period and because population estimates of most ungulate populations had increased by the 1980's. We feel the higher estimates of the 1980's reflect more up-to-date techniques and are most representative of the situation into which the wolves would be reintroduced.

Idaho, Montana, Wyoming↗
USGS1993

Using Pop-II models to predict effects of wolf predation and hunter harvests on elk, mule deer, and moose on the northern range

The effects of establishing a gray wolf ( Canis lupus ) population in Yellowstone National Park were predicted for three ungulate species—elk ( Cervus elaphus ), mule deer ( Odocoileus hemionus ), and moose ( Alces alces )—using previously developed POP-II population models. We developed models for 78 and 100 wolves. For each wolf population, we ran scenarios using wolf predation rates of 9, 12, and 15 ungulates/wolf/year. With 78 wolves and the antlerless elk harvest reduced 27%, our modeled elk population estimated were 5-18% smaller than the model estimate without wolves. With 100 wolves and the antlerless elk harvest reduced 27%, our elk population estimated were 11-30% smaller than the population estimates without wolves. Wolf predation effects were greater on the modeled mule deer population than on elk. With 78 wolves and no antlerless deer harvest, we predicted the mule deer population could be 13-44% larger than without wolves. With 100 wolves and no antlerless deer harvest, the mule deer population was 0-36% larger than without wolves. After wolf recovery, our POP-II models suggested moose harvests would have to be reduced at least 50% to maintain moose numbers at the levels predicted when wolves were not present. Mule deer and moose population data are limited, and these wolf predation effects may be overestimated if population sizes or male-female ratios were underestimated in our population models. We recommend additional mule deer and moose population data be obtained.

Idaho, Montana, Wyoming↗
USGS1992

Cannibalism and predation on black bears by grizzly bears in the Yellowstone ecosystem, 1975-1990

We documented one instance of an adult male grizzly bear preying upon a black bear and four instances where circumstantial evidence suggested that grizzly bears (two cubs-of-the-year, one yearling female that was injured, and one adult male) had been preyed upon by conspecifics. We also examined feces of grizzly bears for bear remains. Remains of bears tended to be more common in spring feces and did not differ in frequency between early and late years of the study. Our observations generally support existing hypotheses concerning cannibalism among bears.

Idaho;Montana;Wyoming↗
USGS1992

Distribution of Yellowstone grizzly bears during the 1980s

Grizzly bear ( Ursus arctos horribilis ) females with young occupied a greater proportion of area east of Yellowstone National Park during 1980-1989 compared to 1973-1979. Occupancy by all bears and females with young was lower in all peripheral areas compared to the Park, but greater east and south compared to north and south of the Park. Observed changes reflect not only a static or slightly increasing population trend, but may also reflect biases in data collection. These biases are discussed and distributions of all observations and females with young are presented. Methodological problems implicit in analyzing changes in distribution of grizzly bears are also discussed.

Idaho, Montana, Wyoming↗
USGS1992

Yellowstone grizzly bear mortality, human habituation, and whitebark pine seed crops

The Yellowstone grizzly bear ( Ursus arctos horribilis ) population may be extirpated during the next 100-200 years unless mortality rates stabilize and remain at acceptable low levels. Consequently, we analyzed relationships between Yellowstone grizzly bear mortality and frequency of human habituation among bears and size of the whitebark pine ( Pinus albicaulis ) seed crop. During years of large seed crops, bears used areas within 5 km of roads and 8 km of developments half as intensively as during years of small seed crops because whitebark pine's high elevation distribution is typically remote from human facilities. On average, management trappings of bears were 6.2 times higher, mortality of adult females 2.3 times higher, and mortality of subadult males 3.3 times higher during years of small seed crops. We hypothesize that high mortality of adult females and subadult males during small seed crop years was a consequence of their tendency to range closest (of all sex-age cohorts) to human facilities; they also had a higher frequency of human habituation compared with adult males. We also hypothesize that low morality among subadult females during small seed crop years was a result of fewer energetic stressors compared with adult females and greater familiarity with their range compared with subadult males; mortality was low even though they ranged close to humans and exhibited a high frequency of human habituation. Human-habituated and food-conditioned bears were 2.9 times as likely to range within 4 km of developments and 3.1 times as often killed by humans compared with nonhabituated bears. We argue that destruction of habituated bears that use native foods near humans results in a decline in the overall ability of bears to use available habitat; and that the number and extent of human facilities in occupied grizzly bear habitat needs to be minimized unless habituated bears are preserved and successful ways to manage the associated risks to humans are developed.

Idaho, Montana, Wyoming↗
USGS1992

Chlamydial-caused infectious keratoconjunctivitis in bighorn sheep of Yellowstone National Park

An epizootic of infectious keratoconjuctivitis occurred in bighorn sheep ( Ovis canadensis ) in Yellowstone National Park during the winter of 1981-82. The causative organism was identified as Chlamydia sp. Mortality related to the epizootic was approximately 60% of an estimated 500 bighorn sheep in the northern range population. The infection probably affected all sex and age classes, but field surveys of live animals and mortality suggested that mature rams died disproportionately. Limited field observations the following winter on individuals having both normal and cloudy-appearing eyes suggested that half of the bighorns then present on the core units of winter range had contracted the disease and survived. By 1988, there were about 300 bighorn sheep in the population.

Idaho, Montana, Wyoming↗
USGS1991

Movements of Yellowstone grizzly bears

Ninety-seven grizzly bears Ursus arctos horribilis were radio-located 6299 times during 1975&ndash;1987. Annual range sizes differed by sex, age, reproductive status and amount of precipitation. Females exhibited greater fidelity to seasonal and annual ranges than males. Weaned female offspring generally remained in the vicinity of the maternal range, while weaned males often made substantial movements to unexplored country. Average total home range size was 884 km 2 for females and 3757 km 2 for males. Males consistently exhibited greater indices of movement and range sizes than females. All cohorts had larger mean ranges during this study than during the period 1959&ndash;1969 when the population had access to open garbage dumps. Movements and elevational distribution of all cohorts were related to availability of whitebark pine Pinus albicaulis seeds. We hypothesized that females with cubs-of-the-year and yearlings were displaced from most productive habitats during seasons and years of limited food availability.

Idaho;Montana;Wyoming↗
USGS1991

Conditions leading to a recent small hydrothermal explosion at Yellowstone National Park

Porkchop Geyser, in Yellowstone National Park, was the site of a small hydrothermal explosion on September 5, 1989. In the early 1960s, this was a quiescent spring with an intermittent seeping discharge. Infrequent geyser eruptions 3-5 m high started in 1971, and in 1985 the geyser began erupting as a perpetual spouter 6-9 m high. Perpetual spouting at the latter height continued until just before the catastrophic hydrothermal event when the geyser column suddenly rose to a height of 20-30 m, followed immediately by the explosive ejection of sinter blocks up to 1.88 m in maximum dimension and formation of an irregular crater 13.9 m long and 11.7 m wide. The ejected blocks show a variety of siliceous deposits indicative of changing environments of deposition with time, and possibly of prior hydrothermal explosive activity at this site. Water samples from Porkchop were collected and analyzed once in the 1920s, again in 1951, ten times between 1960 and mid-1989, and once in January 1990 after the explosion. Chemical geothermometry shows an increase in the temperature of last water-rock equilibration of about 60 to 70 °C from 1962 through 1989. This may have been the result of drawing water progressively from different and hotter regions of a single reservoir or mixing waters from two different reservoirs with a progressively larger proportion of water being drawn from the hotter reservoir from 1962 through 1989. Boiling of ascending fluids coming from hotter subsurface regions resulted in an increase in the proportion of steam to water discharged by the geyser. A constriction at the exit of the geyser tube throttled the flow of water and steam and allowed water in shallow cavities adjacent to the geyser tube to become heated to the boiling point at pressures greater than normal hydrostatic. We hypothesize that a sudden breaking loose of this constriction, likely triggered by a seasonal increase in subsurface boiling throughout Norris Basin, allowed water and steam to be discharged from Porkchop much more rapidly than previously. This resulted in a drop in pressure within the geyser tube, causing water in adjacent connected chambers to become superheated. An ensuing rapid flashing of superheated water to steam within relatively confined spaces resulted in the hydrothermal explosion.

Wyoming↗
USGS1991

Bear feeding activity at alpine insect aggregation sites in the Yellowstone ecosystem

Bears (Ursidae) were observed from fixed-wing aircraft on or near alpine talus in the Shoshone National Forest between 15 June and 15 September in 1981–1989. Bears fed on insect aggregations at 6 known and 12 suspected alpine talus sites, disproportionately more at elevations > 3350 m, on slopes > 30°, and on south- and west-facing aspects. While at these sites, bears almost exclusively ate invertebrates, typically army cutworm moths (Euxoa auxiliaris). Subadult grizzly bears (Ursus arctos horribilis) appeared to be underrepresented at the sites, and proportionate representation of adult females with young appeared to decrease between 15 June and 15 September. Overall, observations of bears at these sites increased between 1981 and 1989. We suggest that alpine insect aggregations are an important food source for bears in the Shoshone National Forest, especially in the absence of high-quality foraging alternatives in July and August of most years.

Idaho;Montana;Wyoming↗
USGS1990

Predatory behavior of grizzly bears feeding on elk calves in Yellowstone National Park

Grizzly bears ( Ursus arctos horribilis ) were observed preying on elk calves ( Cervus elaphus ) on 60 occasions in Yellowstone National Park, with 29 confirmed kills. Some bears were deliberate predators and effectively preyed on elk calves for short periods each spring, killing up to 1 calf daily. Primary hunting techniques were searching and chasing although some bears used a variety of techniques during a single hunt. They hunted both day and night and preyed on calves in the open and in the woods. Excess killing occurred when circumstances permitted. One bear caught 5 calves in a 15-minute interval. Elk used a variety of antipredator defenses and occasionally attacked predacious bears. The current level of this feeding behavior appears to be greater than previously reported. This is probably related to the increased availability of calves providing a greater opportunity for learning, and the adaptation of a more predatory behavior by some grizzly bears in Yellowstone.

Idaho, Montana, Wyoming↗