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At least 1,099 records · Page 61Linked to original sources
USGS2010

Effects of chemical immobilization on survival of African buffalo in the Kruger National Park

Capturing, immobilizing, and fitting radiocollars are common practices in studies of large mammals, but success is based on the assumptions that captured animals are representative of the rest of the population and that the capture procedure has negligible effects. We estimated effects of chemical immobilization on mortality rates of African buffalo (Syncerus caffer) in the Kruger National Park, South Africa. We used a Cox proportional hazards approach to test for differences in mortality among age, sex, and capture classes of repeatedly captured radiocollared buffalo. Capture variables did not improve model fit and the Cox regression did not indicate increased risk of death for captured individuals up to 90 days postcapture [exp (??) = 1.07]. Estimated confidence intervals, however, span from a halving to a doubling of the mortality rate (95% CI = 0.56-2.02). Therefore, capture did not influence survival of captured individuals using data on 875 captures over a 5-year period. Consequently, long-term research projects on African buffalo involving immobilization, such as associated with research on bovine tuberculosis, should result in minimal capture mortality, but monitoring of possible effects should continue.

Journal of Wildlife Management↗
USGS2010

Demographics of an experimentally released population of elk in Great Smoky Mountains National Park

We assessed the potential for reestablishing elk ( Cervus elaphus ) in Great Smoky Mountains National Park (GSMNP), USA, by estimating vital rates of experimentally released animals from 2001 to 2006. Annual survival rates for calves ranged from 0.333 to 1.0 and averaged 0.592. Annual survival for subadult and adult elk (i.e., ≥1 yr of age) ranged from 0.690 to 0.933, depending on age and sex. We used those and other vital rates to model projected population growth and viability using a stochastic individual-based model. The annual growth rate (λ) of the modeled population over a 25-year period averaged 0.996 and declined from 1.059 the first year to 0.990 at year 25. The modeled population failed to attain a positive 25-year mean growth rate in 46.0% of the projections. Poor calf recruitment was an important determinant of low population growth. Predation by black bears ( Ursus americanus ) was the dominant calf mortality factor. Most of the variance of growth projections was due to demographic variation resulting from the small population size ( n = 61). Management actions such as predator control may help increase calf recruitment, but our projections suggest that the GSMNP elk population may be at risk for some time because of high demographic variation.

Great Smoky Mountains National Park↗
USGS2004

Interactions of brown bears, Ursus arctos , and gray wolves, Canis lupus , at Katmai National Park and Preserve, Alaska

We describe several encounters between Brown Bears ( Ursus arctos ) and Gray Wolves ( Canis lupus ) that were observed at Katmai National Park and Preserve in southwest Alaska. Katmai Brown Bears and Gray Wolves were observed interacting in a variety of behavioral modes that ranged from agonistic to tolerant. These observations provide additional insight regarding the behavioral plasticity associated with bear-wolf interactions.

Alaska↗
USGS1999

Reproductive characteristics of migratory golden eagles in Denali National Park, Alaska

We describe reproductive characteristics of Golden Eagles ( Aquila chrysaetos ) breeding in Denali National Park, Alaska during an entire snowshoe hare ( Lepus americanus ) cycle, 1988-1997. Data on nesting eagles were collected at 58 to 72 nesting areas annually using two aerial surveys. Surveys were conducted during the incubation period to determine occupancy and nesting activities and late in the nestling period to count nestlings and determine nesting success. Annual occupancy rates of nesting areas did not vary significantly, whereas laying rates, success rates, and mean brood size varied significantly over the study period. Fledgling production for the study population varied sevenfold during the ten-year period. Laying rates, mean brood size, and overall population productivity were significantly correlated with abundance of cyclic snowshoe hare and Willow Ptarmigan ( Lugopus lagopus ) populations. Reproductive rates of Golden Eagles in Denali were similar to those of Golden Eagles from other high latitude study areas in North America, but lower than for Golden Eagles from temperate zone study areas in North America.

Alaska↗
USGS1997

Long-term limnological data from the larger lakes of Yellowstone National Park, Wyoming, USA

Long-term limnological data from the four largest lakes in Yellowstone National Park (Yellowstone, Lewis, Shoshone, Heart) are used to characterize their limnology and patterns of temporal and spatial variability. Heart Lake has distinctively high concentrations of dissolved materials, apparently reflecting high thermal inputs. Shoshone and Lewis lakes have the highest total SiO 2 concentrations (averaging over 23.5 mg L -1 ), apparently as a result of the rhyolitic drainage basins. Within Yellowstone Lake spatial variability is low and ephemeral for most measured variables, except that the Southeast Arm has lower average Na concentrations. Seasonal variation is evident for Secchi transparency, pH, and total-SiO 2 and probably reflects seasonal changes in phytoplankton biomass and productivity. Total dissolved solids (TDS) and total-SiO 2 generally show a gradual decline from the mid-1970s through mid-1980s, followed by a sharp increase. Ratios of Kjeldahl-N to total-PO 4 (KN:TP) suggest that the lakes, especially Shoshone, are often nitrogen limited. Kjeldahl-N is positively correlated with winter precipitation, but TP and total-SiO 2 are counterintuitively negatively correlated with precipitation. We speculate that increased winter precipitation, rather than watershed fires, increases N-loading which, in turn, leads to increased demand for TP and total SiO 2 .

Wyoming↗
USGS2002

A half century of change in alpine treeline patterns at Glacier National Park, Montana, U.S.A.

Using sequential aerial photography, we identified changes in the spatial distribution of subalpine fir (Abies lasiocarpa) habitat at the alpine treeline ecotone. Six 40-ha study sites in the McDonald Creek drainage of Glacier National Park contained subalpine fir forests that graded into alpine tundra. Over a 46-yr period, altitudinal changes in the location of alpine treeline ecotone were not observed. However, over this 46-yr period the area of krummholz, patch-forest, and continuous canopy forest increased by 3.4%, and tree density increased within existing patches of krummholz and patch-forest. Change in subalpine fir vegetation patterns within 100 m of trails was also compared to areas without trails. Within 100 m of trails, the number of small, discrete krummholz stands increased compared to areas without trails, but there was no significant change in total krummholz area. We used historical terrestrial photography to expand the period (to 70 yr) considered. This photography supported the conclusions that a more abrupt ecotone transition developed from forest to tundra at alpine treeline, that tree density within forested areas increased, and that krummholz became fragmented along trails. This local assessment of fine-grained change in the alpine treeline ecotone provides a comparative base for looking at ecotone change in other mountain regions throughout the world.

Montana↗
USGS1997

Spring feeding on ungulate carcasses by grizzly bears in Yellowstone National Park

We studied the spring use of ungulate carcasses by grizzly bears ( Ursus arctos horribilis ) on ungulate winter ranges in Yellowstone National Park. We observed carcasses and bear tracks on survey routes that were travelled biweekly during spring of 1985-90 in the Firehole-Gibbon winter range and spring of 1987-90 in the Northern winter range. The probability that grizzly bears used a carcass was positively related to elevation and was lower within 400 m of a road, or within 5 km of a major recreational development compared to elsewhere. Carcass use peaked in April, coincident with peak ungulate deaths. Grizzly bears also were more likely to use carcasses in the Firehole-Gibbon compared to Northern Range study area. We attributed the effects of study area and elevation to the fact that grizzly bears den and are first active in the spring at high elevations and to differences in densities of competing scavengers. Probability of grizzly bear use was strongly related to body mass of carcasses on the Northern Range where densities of coyotes ( Canis latrans ) and black bears ( U. americanus ) appeared to be much higher than in the Firehole-Gibbon study area. We suggest that additional restrictions on human activity in ungulate winter ranges or movement of carcasses to remote areas could increase grizzly bear use of carrion. Fewer competing scavengers and greater numbers of adult ungulates vulnerable to winter mortality could have the same effect.

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↗
USGS1990

Bear use of cutthroat trout spawning streams in Yellowstone National Park

Grizzly bears ( Ursus arctos ) and black bears ( U. americanus ) prey on spawning cutthroat trout ( Oncorhynchus clarki , formerly known as Salmo clarki ) in tributary streams of Yellowstone Lake. These tributary streams were surveyed from 1985 to 1987 to determine the presence and level of trout spawning activity and bear use. Indices were developed to enumerate spawner density and levels of bear use. Of 124 known tributaries of Yellowstone Lake, 48% had a spawning run. Of these spawning streams, 93% had associated bear activity, and 61% had associated evidence of bear fishing. Bears were apparently using more spawning streams and fish compared to 10 years earlier. Bear use of cutthroat trout spawning streams appeared to be largely a positive function of volumetric spawner density. We hypothesize that abundance and quality of stream-side vegetation relative to other foraging options influenced bear use. Intra- and interspecific avoidance among bears was suggested by patterns of spawning stream use. Less bear use of spawning streams than expected occurred within 1 km of park developments.

Idaho, Montana, Wyoming↗
USGS2020

A synthesis of ten years of chemical contaminant monitoring data in National Park Service - Southeast and southwest Alaska networks

With the exception of PAHs and trace metals, which were detected at 100% of the sites, all of the other contaminants were detected at varying frequencies. PBBs, Mirex and Endosulfans were not detected in any of the samples and Chlorpyrifos was only detected in five samples across four sites. Chlordanes were present at 79% of the sites while Butyltins were only detected at 20% of the sites. Overall, the majority of the concentrations can be considered to be at background levels when compared to the long-term NOAA National Status and Trends (NS&T) monitoring data for blue mussels nationwide. The relatively high concentrations of cadmium, copper, and nickel in comparison to the NS&T national groups could be a combination of natural inputs and anthropogenic sources. The natural exposure and weathering of rocks in southern Alaska can contribute to elevated background concentrations of these metals. Sample concentrations, compositions and/or trends for Total DDT, Total Dieldrins and Total HCHs suggest that these contaminants are no longer bioaccumulating at detectable levels. Total Butyltin concentrations were low compared to the NS&T national concentrations, but the presence of tributyltin (TBT) in recent years at Sitka Visitor's Center (SITK) and Skagway Harbor (SKWY) indicates that fresh sources of Butyltin are still entering these environments, probably through vessel traffic at these sites. The PAH profiles and higher concentrations at SITK, SKWY and Nahku Bay East Side (NBES) suggest that these sites are receiving anthropogenic sources of PAH contamination. The results included in this report help to provide a greater understanding of general background contamination in NPS SWAN and SEAN parks, as well as other monitoring sites, including range, trends and variability. Future monitoring should aim to continue analyzing the temporal trends of these contaminants on a regional scale through periodic sampling as well as focusing on areas of interest that could shed further insight on range and variation (see supplemental material).

Alaska↗
USGS2017

Seasonal and diel environmental conditions predict western pond turtle (Emys marmorata) behavior at a perennial and an ephemeral stream in Sequoia National Park, California

Managers making decisions may benefit from a well-informed understanding of a species' population size and trends. Given the cryptic nature and habitat characteristics of the western pond turtle ( Emys marmorata ), however, imperfect detection may be high and population estimates are frequently varied and unreliable. As a case study to investigate this issue, we used temperature dataloggers to examine turtle behavior at 2 long-term monitoring sites with different hydrological characteristics in Sequoia National Park, California, to determine if common stream-survey techniques are consistent with site-specific turtle behavior. Sycamore Creek is an intermittent stream that dries up every summer while the North Fork Kaweah River flows year-round. We found that while turtles spent most of the recorded time in the water (55% in Sycamore Creek and 82% in the North Fork Kaweah River), the timing of traditional surveys only coincided with the turtles' aquatic activity in the North Fork Kaweah River. At Sycamore Creek, turtles were most likely to be in the water at night. In contrast, failure to detect turtles in North Fork Kaweah River is likely owing to the larger size and complexity of the underwater habitat. In both streams, turtles were also more likely to be in the water in the weeks leading up to important changes in hydroperiods. Our findings illustrate the effects that differences in water permanence can have on turtle behavior within the same watershed and how phenotypic plasticity may then affect detection during surveys. Our study highlights the importance of tailoring survey practices to the site-specific behavioral traits of the target species.

California↗
USGS2011

Fine-scale spatio-temporal variation in tiger Panthera tigris diet: Effect of study duration and extent on estimates of tiger diet in Chitwan National Park, Nepal

Attempts to conserve declining tiger Panthera tigris populations and distributions have experienced limited success. The poaching of tiger prey is a key threat to tiger persistence; a clear understanding of tiger diet is a prerequisite to conserve dwindling populations. We used unpublished data on tiger diet in combination with two previously published studies to examine fine-scale spatio-temporal changes in tiger diet relative to prey abundance in Chitwan National Park, Nepal, and aggregated data from the three studies to examine the effect that study duration and the size of the study area have on estimates of tiger diet. Our results correspond with those of previous studies: in all three studies, tiger diet was dominated by members of Cervidae; small to medium-sized prey was important in one study. Tiger diet was unrelated to prey abundance, and the aggregation of studies indicates that increasing study duration and study area size both result in increased dietary diversity in terms of prey categories consumed, and increasing study duration changed which prey species contributed most to tiger diet. Based on our results, we suggest that managers focus their efforts on minimizing the poaching of all tiger prey, and that future studies of tiger diet be of long duration and large spatial extent to improve our understanding of spatio-temporal variation in estimates of tiger diet.

Chitwan National Park↗
USGS2017

Monitoring eradication of European mouflon sheep from the Kahuku Unit of Hawai‘i Volcanoes National Park

European mouflon ( Ovis gmelini musimon ), the world's smallest wild sheep, have proliferated and degraded fragile native ecosystems in the Hawaiian Islands through browsing, bark stripping, and trampling, including native forests within Hawai‘i Volcanoes National Park (HAVO). HAVO resource managers initiated ungulate control efforts in the 469 km 2 Kahuku Unit after it was acquired in 2003. We tracked control effort and used aerial surveys in a 64.7 km 2 area from 2004 to 2017 and more intensive ground surveys and camera-trap monitoring to detect the last remaining animals within a 25.9 km 2 subunit after it was enclosed by fence in 2012. Aerial shooting yielded the most removals per unit effort (3.2 animals/ hour), resulting in 261 animals. However, ground-based methods yielded 4,607 removals overall, 3,038 of which resulted from assistance of volunteers. Ground shooting with dogs, intensive aerial shooting, ground sweeps, and forward-looking infrared (FLIR)-assisted shooting were necessary to find and remove the last remaining mouflon. The Judas technique, baiting, and trapping were not successful in attracting or detecting small numbers of remaining individuals. Effort expended to remove each mouflon increased nearly 15-fold during the last 3 yr of eradication effort from 2013 to 2016. Complementary active and passive monitoring techniques allowed us to track the effectiveness of control effort and reveal locations of small groups to staff. The effort and variety of methods required to eradicate mouflon from an enclosed unit of moderate size illustrates the difficulty of scaling up to entire populations of wild ungulates from unenclosed areas.

Hawai'i↗
USGS2022

Status of landbirds in the National Park of American Samoa

The National Park of American Samoa (NPSA) was surveyed in 2011 and 2018 using point-transect distance sampling to estimate trends in landbird distribution, composition, population density, and abundance. Surveys were conducted within the Ta‘ū Unit and Tutuila Unit, each on separate islands of American Samoa. We detected a total of 14 species during surveys and there were sufficient detections of seven species to allow for density estimation and abundance within each unit. We assessed differences in density between surveys with a two-sample z -test and found significant declines of Blue-crowned Lorikeets ( Vini australis ) in the Ta‘ū Unit, and of Samoan Starlings ( Aplonis atrifusca ) in the Tutuila Unit. Density estimates of the Crimson-crowned Fruit Dove ( Ptilinopus porphyraceus ), Pacific Kingfisher ( Todiramphus sacer ), Polynesian Wattled Honeyeater ( Foulehaio carunculatus ), and Samoan Starling (in the Ta‘ū Unit) were also lower in 2018 than 2011, but differences were inconclusive because of relatively large variance estimates. Densities of the Polynesian Starling ( Aplonis tabuensis ) and Pacific Imperial Pigeon ( Ducula pacifica ) in the Ta‘ū Unit were higher in 2018 than 2011, but differences were similarly inconclusive. Lower 2018 densities could be due to Tropical Cyclone Gita that struck the islands just four months before the surveys. We provide indices of relative occurrence and abundance for the remaining seven species detected, which include the Many-colored Fruit Dove ( Ptilinopus perousii ) and the rarely detected Spotless Crake ( Zapornia tabuensis )—both of which are species of concern in American Samoa.

National Park of American Samoa, Ofu-Olosega, Ta'u↗
USGS2020

Tree mortality in blue oak woodland during extreme drought in Sequoia National Park, California

Blue oak woodlands in California have been a focus of conservation concern for many years. Numerous studies have found that existing seedling and sapling numbers are inadequate to sustain current populations, and recent work has suggested that blue oak woodlands might be particularly vulnerable to a warming climate. California has recently experienced a drought of historically unprecedented severity, resulting in the mortality of tens of millions of trees, including an apparent spike in mortality in oak communities. Here we present the results of a survey of tree mortality and composition in blue oak woodlands in Sequoia National Park. We found that 18% (95% CI = 14–24,) of all standing trees and 23% (95% CI = 17–30) of standing Quercus douglasii Hook. & Arn. (blue oak) were dead, substantially higher than proportions of dead trees recorded in pre-drought datasets, which showed 4% (95% CI = 2–9) standing dead for all trees and 5% (95% CI = 4–7) dead or 8% (95% CI = 4–16) standing dead for blue oak. Furthermore, much of this mortality appeared to be recent. Based on foliage or fine twig retention, 19% (95% CI = 14–26) of blue oak and 23% (95% CI = 16–31) of Quercus wislizeni A. DC. (interior live oak) appear to have died recently. In contrast, only 5% (95% CI = 3–8) of Aesculus californica (Spach) Nutt. (California buckeye) and 5% (95% CI = 2–11) of Fraxinus dipetala Hook. & Arn. (California ash) appear to have died recently. Even after such high mortality, with blue oak basal area dropping by 26% (from 9.5 m2/ha [95% CI = 7.4–11.6] to 7.0 m2/ha [95% CI = 5.3–8.7]), blue oak remains the dominant species in these ecosystems. However, given the lack of recruitment and the apparent vulnerability to extreme drought, blue oak populations may be at risk for severe decline if such mortality events become more frequent.

California↗
USGS2002

History of pronghorn population monitoring, research, and management in Yellowstone National Park

Pronghorn antelope in Yellowstone National Park (YNP) persist in a small population that historically has experienced recurrent, sometimes dramatic declines. They apparently are isolated from other pronghorns, depend partly on private lands for winter range, experience heavy predation of fawns, and concentrate during winter in a relatively small area, thereby increasing their vulnerability to factors like disease or locally extreme weather. Overall, the situation raises serious concerns about the long-term viability of this population. Although such concerns are not new, evidence of a dramatic population decline since 1991 and continued poor recruitment has created a renewed sense of urgency. Recent efforts to revitalize pronghorn research in YNP began with fawn recruitment and habitat use studies, initiated in 1999 and 2000. With those studies drawing to a close, YNP is reviewing the status and direction of its pronghorn program. The Yellowstone Pronghorn Conservation Assessment Workshop was convened in YNP in January, 2002, to appraise the current state of knowledge about this pronghorn population and make recommendations about future management and research needs. A review of pronghorn population change, management, and research in YNP was commissioned in May, 2001, to provide historical background for workshop participants. Following is a written summary of that review. The process of locating materials for this review was limited to 3 months. Not all relevant materials were discovered or reviewed in that time. In particular, it was not possible to find and review all original sources of information. Also, except for occasional anecdotal accounts, weather records were not reviewed, leaving a potentially serious gap in our understanding of the forces driving changes in pronghorn population counts and estimates 2 over time. Despite these deficiencies, considerable information was reviewed, earlier summaries of population classification and count data were updated, and previously uncited sources of information were identified that challenge important aspects of previous interpretations of the history of pronghorns and pronghorn management in YNP. Information is grouped into 4 major subject areas: distribution and habitat use, demographics and management, genetics, and disease.

Wyoming↗
USGS1972

Geology and Mineral Resources of the Northern Part of the North Cascades National Park, Washington

The northern part of the North Cascades National Park in northern Washington is north of the Skagit River between Mount Shuksan on the West and Ross Lake on the east. The area occupies approximately 500 square miles of steep mountains and thickly forested valleys centered on the precipitous Picket Range. Old metamorphic rocks and young volcanic and sedimentary rocks are intruded by large masses of granitic rocks that together form a diverse, complicated, but well-exposed geologic section. The granitic rocks are the most abundant in the area; they intrude most of the other rocks, and they separate one suite of rocks in the eastern part of the area from a second suite in the western part. In the eastern part of the area, the oldest rocks are the Custer Gneiss of McTaggart and Thompson, a thick sequence of biotite and hornblende gneisses and schists. We have divided these rocks into three generalized units: light-colored gneiss, banded gneiss, and amphibole-rich gneiss. To the northeast of these rocks lies a metagabbro. This rock type is complex and is made up of several types of gabbro, diorite, amphibolite, ultramafic rocks, and quartz diorite that crop out along the Ross Lake fault zone. To the northeast of these rocks and also along the Ross Lake fault zone is the phyllite and schist of Ross Lake. These rocks are the highly sheared and metamorphosed equivalents of the plagioclase arkose and argillite sequence of Jurassic and Cretaceous age that is so widespread on the east side of Ross Lake. The Cretaceous Hozomeen Group of Cairnes lies along Ross Lake northeast of the phyllite and schist and consists mainly of slightly metamorphosed greenstones with subordinate chert and phyllite. The phyllite in this unit is similar to that in the underlying phyllite and schist of Ross Lake with which it appears to be interbedded. The youngest rocks in the eastern part of the area are the Skagit Volcanics a thick sequence of welded tuff-breccia with some flows and air-laid tuffs. These rocks, which are probably early Tertiary in age, overlie the Hozomeen Group and the Custer Gneiss along the Canadian border. In the western part of the area the oldest rocks are greenschist and phyllite of Mount Shuksan. These fine-grained foliated and crinkled rocks commonly contain narrow lenses or layers of quartz. They are unconformably overlain by the Chuckanut Formation in the southern part of the area. This formation, which is of Paleocene and Late Cretaceous age, is made up mainly of gently dipping plagioclase arkose with some interbedded black argillite and conglomerate. The Hannegan Volcanics overlie the Chuckanut in the northern part of the area and the greenschist and phyllite of Mount Shuksan in the central part. The Hannegan Volcanics which are of early Tertiary age, consist principally of air-laid volcanic breccias and tuffs, but also include some flows and one small porphyry stock. The Chilliwack composite batholith consists of several types of granitic rocks, which were intruded at different times in the Tertiary. The two principal rock types are granodiorite and quartz diorite, but small bodies of quartz monzonite diorite, and alaskite are found in many parts of the area. Contacts between the various rock types may be either abrupt or gradational. All rocks of the Chilliwack batholith are younger than the other rock types except the Skagit and Hannegan Volcanics, which are in part younger than rocks of the batholith. At least two periods of deformation are indicated by the tight folding of the older Custer Gneiss and the greenschist and phyllite of Mount Shuksan and the gentle folding of the younger Chuckanut Formation. At least three periods of faulting occurred, one before and two after the intrusion of the Chilliwack batholith. The two largest fault structures are the Ross Lake fault zone and a long northeast-striking fault that extends for 20 miles from Mount Shuksan down the Chilliwack Valley. The Ross Lake fault zone is pro

Washington↗