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USGS2003

Research observation: Hydrolyzable and condensed tannins in plants of northwest Spain forests

Tannins are secondary metabolites that may influence feeding by mammals on plants . We analyzed hydrolyzable and condensed tannins in 30 plant species consumed by livestock and deer, as a preliminary attempt to study their possible implications on browsing and grazing in forest ecosystems. Heathers ( Ericaceae ) and plants of the Rose ( Rosaceae ) family had tannins , while forbs, grasses and shrubs other than the heathers did not show astringency properties. We found the highest tannin content of all the species in Rubus sp., with the highest value around 180 mg TAE/g dry weight in spring. Potentilla erecta , Alnus glutinosa and Quercus robur were next with 57 to 44 mg TAE/g dw. Total tannins in heathers ranged from 22 to 36 mg TAE/g dw. Levels of condensed tannins were higher than hydrolyzable for most of the species. Only Betula alba , Calluna vulgaris , Pteridium aquilinum and Vaccinium myrtillus had 100% hydrolyzable tannins . Tannin content of the species changed seasonally with highest values during the growing season, corresponding to late winter or early spring, depending on the species.

northwest Spain↗

USGS2003

A method for determining the onset year of intense browsing

McAuliffe studied the factors limiting seedling establishment of a common Sonoran Desert tree, Cercidium microphyllum, at three sites in bajada habitat in Arizona and Mexico. Distribution patterns of Cercidium seedlings in both habitats were random when seedlings emerged, however, seedling distribution in bajadas quickly became non-random and associated with other perennial plants. Seedlings closely associated with (rooted under) shrubby perennial vegetation survived because they had some protective cover and were not grazed by rabbits, however, future survival of these seedlings may be reduced due to competition with the protective plants. The authors concluded that herbivory was the main factor limiting the establishment of Cercidium microphyllum seedlings in the bajada habitats in the Sonoran desert.

Montana↗

USGS1999

Effects of sample size on kernel home range estimates

Kernel methods for estimating home range are being used increasingly in wildlife research, but the effect of sample size on their accuracy is not known. We used computer simulations of 10-200 points/home range and compared accuracy of home range estimates produced by fixed and adaptive kernels with the reference (REF) and least-squares cross-validation (LSCV) methods for determining the amount of smoothing. Simulated home ranges varied from simple to complex shapes created by mixing bivariate normal distributions. We used the size of the 95% home range area and the relative mean squared error of the surface fit to assess the accuracy of the kernel home range estimates. For both measures, the bias and variance approached an asymptote at about 50 observations/home range. The fixed kernel with smoothing selected by LSCV provided the least-biased estimates of the 95% home range area. All kernel methods produced similar surface fit for most simulations, but the fixed kernel with LSCV had the lowest frequency and magnitude of very poor estimates. We reviewed 101 papers published in The Journal of Wildlife Management (JWM) between 1980 and 1997 that estimated animal home ranges. A minority of these papers used nonparametric utilization distribution (UD) estimators, and most did not adequately report sample sizes. We recommend that home range studies using kernel estimates use LSCV to determine the amount of smoothing, obtain a minimum of 30 observations per animal (but preferably a?Y50), and report sample sizes in published results.

Journal of Wildlife Management↗

USGS2022

Annotated bibliography of scientific research on pygmy rabbits published from 1990 to 2020

Integrating recent scientific knowledge into management decisions supports effective natural resource management and can lead to better resource outcomes. However, finding and accessing scientific knowledge can be time consuming and costly. To assist in this process, the U.S. Geological Survey (USGS) is creating a series of annotated bibliographies on topics of management concern for western lands. Previously published reports introduced a methodology for preparing annotated bibliographies to facilitate the integration of recent, peer-reviewed science into resource management decisions. Therefore, relevant text from those efforts is reproduced here to frame the presentation. Sagebrush ecosystems throughout North America face management challenges including habitat loss and fragmentation. Brachylagus idahoensis (pygmy rabbits) are a sagebrush-obligate species that has experienced population declines and range contraction in recent decades. A disjunct population of pygmy rabbits in the Columbia Basin in Washington was listed as federally endangered in 2003. Due to their specialized habitat requirements and low dispersal ability, pygmy rabbits are a high priority for managers throughout their range. We compiled and summarized peer-reviewed journal articles, data products, and formal technical reports (such as U.S. Forest Service General Technical Reports and U.S. Geological Survey Open-File Reports) on pygmy rabbits published between January 1, 1990 and December 31, 2020. We first conducted a structured search of three reference databases and three government databases using the phrase “pygmy rabbit” or “ Brachylagus idahoensis .” We refined the initial list of products by removing (1) duplicates, (2) products not written in English, (3) publications that were not focused on North America, (4) publications that were not published as research, data products, or scientific review articles in peer-reviewed journals or as formal technical reports, and (5) products for which pygmy rabbits were not a research focus or for which the study did not present new data or findings about pygmy rabbits. We summarized each product using a consistent structure (background, objectives, methods, location, findings, and implications) and identified the management topics (for example, captive breeding, habitat characteristics, and population estimates) addressed by each product. We also noted which publications included new publicly available geospatial data. The review process for this annotated bibliography included an initial internal colleague review of each summary, requesting input on each summary from an author of the original publication, and a formal peer review. Our initial searches resulted in 2,285 total products, of which 105 met our criteria for inclusion. Sensitive/rare wildlife, behavior or demographics, site-scale habitat characteristics, habitat selection, and effects distances or spatial scale were the management topics most commonly addressed. The online version of this bibliography, Science for Resource Managers, will be searchable by topic, location, and year; it will include links to each original publication, where available. The studies compiled and summarized here may inform planning and management actions that seek to maintain and restore sagebrush landscapes and associated native species across the western United States.

Open-File Report↗

USGS1994

Bald eagle nest site characteristics in South Florida

Florida had nearly 20% of the coterminous United States population of nesting bald eagles ( Haliaeetus leucocephalus ) in 1990 (U.S. Fish and Wildl. Serv. 1991), yet the nesting ecology of bald eagles in subtropical environments has not been investigated. We examined nest site selection (n = 156 sites) by bald eagles in Florida Bay, Florida, from 1959 to 1990. Black ( Avicennia germinans ) and red mangroves ( Rhizophora mangle ) were used as nest trees almost exclusively (96.9%), and more than half were snags. Eagles also built nests on the ground (n = 3) and raised young on the ground after nests collapsed (n = 5). Eagles preferred (P < 0.05) higher keys (grass, hardwood-buttonwood [ Conocarpus erecta ]) over low-lying keys (mangrove, marsh) for nesting. Management strategies should include the preservation of live and dead mangroves and large, undisturbed keys as potential nesting sites for bald eagles in the subtropical portion of the eagle's range.

Florida↗

USGS2007

Climate change: Potential impacts and interactions in wetlands of the United States

Wetlands exist in a transition zone between aquatic and terrestrial environments which can be altered by subtle changes in hydrology. Twentieth century climate records show that the United States is generally experiencing a trend towards a wetter, warmer climate; some climate models suggest that his trend will continue and possibly intensify over the next 100 years. Wetlands that are most likely to be affected by these and other potential changes (e.g., sea-level rise) associated with atmospheric carbon enrichment include permafrost wetlands, coastal and estuarine wetlands, peatlands, alpine wetlands, and prairie pothote wetlands. Potential impacts range from changes in community structure to changes in ecological function, and from extirpation to enhancement. Wetlands (particularly boreal peatlands) play an important role in the global carbon cycle, generally sequestering carbon in the form of biomass, methane, dissolved organic material and organic sediment. Wetlands that are drained or partially dried can become a net source of methane and carbon dioxide to the atmosphere, serving as a positive biotic feedback to global warming. Policy options for minimizing the adverse impacts of climate change on wetland ecosystems include the reduction of current anthropogenic stresses, allowing for inland migration of coastal wetlands as sea-level rises, active management to preserve wetland hydrology, and a wide range of other management and restoration options.

Journal of the American Water Resources Associatio↗

USGS1987

Incorporating activity time in harmonic home range analysis

The amount of time an animal spends in particular areas is an important aspect of estimating its home range and activity pattern. Calculations of home range using the harmonic mean can be modified to reflect the amount of time or the type of activity observed at each location. The relative time spent at each location may be used to calculate a time-weighted harmonic home range and associated use pattern. This time-weighted harmonic mean approach provides a method for incorporating bursts of relocation data into a home range analysis or identifying activity areas within the home range.

Journal of Wildlife Management↗

USGS1997

Use of lodgepole pine cover types by Yellowstone grizzly bears

Lodgepole pine ( Pinus contorta ) forests are a large and dynamic part of grizzly bear ( Ursus arctos ) habitat in the Yellowstone ecosystem. Research in other areas suggests that grizzly bears select for young open forest stands, especially for grazing and feeding on berries. Management guidelines accordingly recommend timber harvest as a technique for improving habitat in areas potentially dominated by lodgepole pine. In this paper I examine grizzly bear use of lodgepole pine forests in the Yellowstone area, and test several hypotheses with relevance to a new generation of management guidelines. Differences in grizzly bear selection of lodgepole pine cover types (defined on the basis of stand age and structure) were not pronounced. Selection furthermore varied among years, areas, and individuals. Positive selection for any lodgepole pine type was uncommon. Estimates of selection took 5-11 years or 4-12 adult females to stabilize, depending upon the cover type. The variances of selection estimates tended to stabilize after 3-5 sample years, and were more-or-less stable to slightly increasing with progressively increased sample area. There was no conclusive evidence that Yellowstone's grizzlies favored young (<40 yr) stands in general or for their infrequent use of berries. On the other hand, these results corroborated previous observations that grizzlies favored open and/or young stands on wet and fertile sites for grazing. These results also supported the proposition that temporally and spatially robust inferences require extensive, long-duration studies, especially for wide-ranging vertebrates like grizzly bears.

Wyoming↗

USGS2010

Bighorn sheep response to road-related disturbances in Rocky Mountain National Park, Colorado

Bighorn sheep (Ovis canadensis) use of Sheep Lakes mineral site, Rocky Mountain National Park, Colorado, USA, has decreased since 1996. Officials were concerned that human disturbance may have been contributing to this decline in use. We evaluated effects of vehicular traffic and other road-related disturbance on bighorn use of Sheep Lakes in the summers of 2002 and 2003. We found that the time and number of attempts required by bighorn to reach Sheep Lakes was positively related to the number of vehicles and people present at Sheep Lakes. Further, the number of bighorn individuals and groups attempting to visit Sheep Lakes were negatively affected by disturbance associated with the site. The number of vehicles recorded the hour before bighorn tried to access Sheep Lakes best predicted an animal's failure to cross Fall River Road and reach Sheep Lakes. We conclude that human and road-related disturbance at Sheep Lakes negatively affected bighorn use of the mineral site. Because Sheep Lakes may be important for bighorn sheep, especially for lamb production and survival, the negative influence of disturbance may compromise health and productivity of the Mummy Range bighorn sheep.

Journal of Wildlife Management↗

USGS1990

Monitoring moisture storage in trees using time domain reflectometry

Laboratory and field tests were performed to examine the feasibility of using time domain reflectometry (TDR) to monitor changes in the moisture storage of the woody parts of trees. To serve as wave guides for the TDR signal, pairs of stainless steel rods (13 cm long, 0.32 cm in diameter, and 2.5 cm separation) were driven into parallel pilot holes drilled into the woody parts of trees, and a cable testing oscilloscope was used to determine the apparent dielectric constant. A laboratory calibration test was performed on two sapwood samples, so that the relation between the volumetric water content and the apparent dielectric constant of the sapwood could be determined over a range of water contents. The resulting calibration curve for these sapwood samples was significantly different than the general calibration curve used for soils, showing a smaller change in the apparent dielectric constant for a given change in the volumetric water content than is typical for soils. The calibration curve was used to estimate the average volumetric water content to a depth of 13 cm in living trees. One field experiment was conducted on an English walnut tree ( Juglans regia ) with a diameter of 40 cm, growing in a flood-irrigated orchard on a Hanford sandy loam near Modesto, California (U.S.A.). Rods were driven into the tree at about 50 cm above the soil surface and monitored hourly for the month of August, 1988. The moisture content determined by TDR showed a gradual decrease from 0.44 to 0.42 cm 3 cm −3 over a two week period prior to flood irrigation, followed by a rapid rise to 0.47 cm 3 cm −3 over a four day period after irrigation, then again a gradual decline approaching the next irrigation. A second field experiment was made on ten evergreen and deciduous trees with diameters ranging from 30 to 120 cm, growing in the foothills of the Coast Range of central California. Rods were driven into each tree at 50 to 100 cm above the soil surface and monitored on a biweekly to monthly basis for over a year. Most trees showed an early spring maximum in moisture content determined by TDR associated with leaf growth, and a late summer minimum in moisture content associated with the end of the dry season. Moisture contents ranged from 0.20 to 0.70 cm 3 cm −3 , with an annual percentage change in moisture of 15% to 70% depending on species and environmental conditions. A final field test was performed in northern New Mexico (U.S.A.) to examine the effect of trunk freezing on TDR measurements. This test confirmed that freezing conditions were recorded as a total loss of liquid water by the TDR method. These results suggest that further TDR calibration for wood, plus some understanding of the relation between tree moisture and physiological stress could be useful to several disciplines, ranging from irrigation scheduling to watershed management to forest ecology.

California↗

USGS1993

A prepositioned areal electrofishing apparatus for sampling stream habitats

We describe the design, use, and sampling characteristics ofan electrofishing apparatus used to sample fish in stream habitats. The apparatus uses two prepositioned areal electrofishing devices (PAED) of different designs, a bottom parallel electrode PAED and a suspended dropper electrode PAED. To determine the effective immobilization ranges of the PAEDs, we evaluated intensities and shapes of the PAEDs' electrical fields, and the electroshock responses of fish in cages in concrete tanks and in four streams in Alabama with different water conductivities. Electroshock responses indicated that complete immobilization occurred at voltage gradients of 1.0 V/cm or higher (voltage drop, 400 V AC), as far as 35 cm from the PAED electrodes, although some fish were immobilized up to 65 cm away at 0.3 V/cm. We estimated the immobilization (stun) power density threshold to be about 10 μW/cm3. Stream evaluations of the PAEDs revealed that higher voltages were needed to immobilize fish at lower (35 μS/cm) and higher (120 and 125 μS/cm) water conductivities, whereas lower voltages were required at an intermediate conductivity (60 μS/cm). These results conformed with the predictions of power transfer theory and underscored the need to calibrate PAEDs to stream conductivities to standardize the effective sampling range.

North American Journal of Fisheries Management↗

USGS1999

Effects of drought on desert tortoise movement and activity

We monitored movement and activity patterns of 38 desert tortoises (Gopherus agassizii) at 2 locations in the southcentral Mojave Desert during 2 consecutive years differing markedly in winter rainfall. During the first year, winter precipitation was 225% greater than the long-term average for this region, whereas a drought the following year resulted in precipitation that was 25% of the long-term average. These winter rains produced 2 distinct patterns of annual plant productivity: a bloom of annuals the first year, followed by their complete absence the second year. As measured by radiotelemetry, home range size, the number of different burrows used, average distances traveled per day, and levels of surface versus burrow activity were significantly reduced in both populations during the drought year. The pooled distribution of between-observation distances traveled showed a shift favoring shorter-distance movements during the drought year. Differences in levels of winter precipitation between years and the resulting variation of winter annual biomass in the spring appear to play a significant role in desert tortoise movement and activity patterns. Future management and conservation plans for the desert tortoise should consider weather and productivity as important factors influencing annual home range size, number of burrows used, average distances traveled, and activity levels.

Journal of Wildlife Management↗

USGS2018

Movement and diel habitat use of juvenile Neosho Smallmouth Bass in an Ozark stream

Documenting fish movement patterns and examining relationships with both fish and habitat characteristics are essential aspects of sound conservation and management. Stream fish movement and habitat use have been associated with a myriad of factors, and variability among individuals is common. Movement and habitat use patterns of juvenile Smallmouth Bass Micropterus dolomieu in streams are poorly understood, particularly for the Neosho subspecies M. dolomieu velox . Our study objective was to determine diel movement patterns and microhabitat use by juvenile Neosho Smallmouth Bass during late autumn. In 2016, we surgically implanted radio transmitters into 13 juvenile Smallmouth Bass in Honey Creek, Oklahoma. We tracked the fish by using radiotelemetry on 41 occasions over the 26‐d tag life and located fish throughout the diel cycle to characterize movement and habitat use. Movement patterns varied among individual fish, with cumulative movements ranging from 33 to 1,302 m. Incremental displacement (the distance moved between two consecutive relocations) increased slightly with warmer water temperatures and increasing fish size. Although there was also considerable individual variation in habitat use patterns, deeper habitats were associated with larger juvenile Smallmouth Bass and daytime. Fish also tended to use higher‐velocity habitats during the day, and this trend increased over the duration of the study. Our results suggest high individual variation in both movement and habitat use by juvenile Neosho Smallmouth Bass across the diel cycle. We show that juvenile Smallmouth Bass move among microhabitats and would benefit from management actions that maintain and promote instream habitat complexity. Future efforts focused on juvenile Smallmouth Bass movement over longer time periods would be beneficial for understanding movement and habitat use dynamics across a greater range of seasonal and environmental variability.

Oklahoma↗

USGS2011

Fire, grazing history, lichen abundance, and winter distribution of caribou in Alaska's taiga

In the early 1990s the Nelchina Caribou ( Rangifer tarandus ) Herd (NCH) began a dramatic shift to its current winter range, migrating at least an additional 100 km beyond its historic range. We evaluated the impacts of fire and grazing history on lichen abundance and subsequent use and distribution by the NCH. Historic (prior to 1990) and current (2002) winter ranges of the NCH had similar vascular vegetation, lichen cover ( P = 0.491), and fire histories ( P = 0.535), but the former range had significantly less forage lichen biomass as a result of grazing by caribou. Biomass of forage lichens was twice as great overall ( P = 0.031) and 4 times greater in caribou selected sites on the current range than in the historic range, greatly increasing availability to caribou. Caribou on the current range selected for stands with >20% lichen cover ( P < 0.001), greater than 1,250 kg/ha ( P < 0.001) forage lichen biomass and stands older than 80 yr postfire ( P < 0.001). After fires, forage lichen cover and biomass seldom recovered sufficiently to attract caribou grazing until after ≥60 yr, and, as a group, primary forage lichen species did not reach maximum abundance until 180 yr postfire. Recovery following overgrazing can occur much more quickly because lichen cover, albeit mostly fragments, and organic substrates remain present. Our results provide benchmarks for wildlife managers assessing condition of caribou winter range and predicting effects of fires on lichen abundance and caribou distribution. Of our measurements of cover and biomass by species, densities and heights of trees, elevation, slope and aspect, only percentage cover by Cladonia amaurocraea , Cladina rangiferina , Flavocetraria cuculata , and lowbush cranberry ( Vaccinium vitis‐idaea ) were necessary for predicting caribou use of winter range.

Journal of Wildlife Management↗

USGS2013

Broad-scale patterns of Brook Trout responses to introduced Brown Trout in New York

Brook Trout Salvelinus fontinalis and Brown Trout Salmo trutta are valuable sport fish that coexist in many parts of the world due to stocking introductions. Causes for the decline of Brook Trout within their native range are not clear but include competition with Brown Trout, habitat alteration, and repetitive stocking practices. New York State contains a large portion of the Brook Trout's native range, where both species are maintained by stocking and other management actions. We used artificial neural network models, regression, principal components analysis, and simulation to evaluate the effects of Brown Trout, environmental conditions, and stocking on the distribution of Brook Trout in the center of their native range. We found evidence for the decline of Brook Trout in the presence of Brown Trout across many watersheds; 22% of sampled reaches where both species were expected to occur contained only Brown Trout. However, a model of the direct relationship between Brook Trout and Brown Trout abundance explained less than 1% of data variation. Ordination showed extensive overlap of Brook Trout and Brown Trout habitat conditions, with only small components of the hypervolume (multidimensional space) being distinctive. Subsequent analysis indicated higher abundances of Brook Trout in highly forested areas, while Brown Trout were more abundant in areas with relatively high proportions of agriculture. Simulation results indicated that direct interactions and habitat conditions were relatively minor factors compared with the effects of repeated stocking of Brown Trout into Brook Trout habitat. Intensive annual stocking of Brown Trout could eliminate resident Brook Trout in less than a decade. Ecological differences, harvest behavior, and other habitat changes can exacerbate Brook Trout losses. Custom stocking scenarios with Brown Trout introductions at relatively low proportions of resident Brook Trout populations may be able to sustain healthy populations of both species within their present range.

New York↗

USGS2019

Coldwater periods in warmwater streams: Microhabitat shifts from autumn to winter by Smallmouth Bass

Seasonal and life stage variation in microhabitat use is an important driver of fish survival and bioenergetics, but knowledge of microhabitat selection during colder periods is generally lacking in warmwater streams. Our objective was to examine changes in microhabitat selection by age‐0 (TL ≤ 85 mm) and age‐1+ (TL > 85 mm) Smallmouth Bass Micropterus dolomieu from autumn to winter in streams of the southwest Ozark Highlands ecoregion. We examined microhabitat selection (depth, velocity, substrate, cover, and temperature) during autumn 2017 (Spavinaw Creek) and winter 2018 (Spavinaw and Spring creeks). During autumn and winter, age‐0 fish selected intermediate depths of approximately 1 m, whereas age‐1+ fish selected the deepest available habitat. Water depth selection was similar across seasons for both life stages. Both age‐0 and age‐1+ bass selected areas of zero velocity, increasing substrate size, instream cover, and warmwater patches in autumn. Velocity selection differed between autumn and winter with both life stages showing stronger selection of low velocity patches (0.1–0.3 m/s) during winter. Both life stages shifted to having no substrate selection during winter. Age‐1+ bass were more likely than age‐0 bass to use cover during autumn, but this relationship shifted in winter to the age‐0 cohort increasing their selection of cover and the age‐1+ cohort decreasing their selection. Both age‐0 and age‐1+ bass selected relatively warmer habitats during autumn, but not winter. Collectively, our results highlight both seasonal and life stage variation in Smallmouth Bass microhabitat selection. As our understanding of habitat selection across seasons develops, the management of Smallmouth Bass will undoubtedly improve. Changing environmental conditions over time may influence available habitat as well as the timing of seasonal shifts across a range of spatial and temporal scales, including microhabitat patches.

Arkansas, Oklahoma↗

USGS2011

Nutrient loadings to streams of the continental United States from municipal and industrial effluent?

Data from the United States Environmental Protection Agency Permit Compliance System national database were used to calculate annual total nitrogen (TN) and total phosphorus (TP) loads to surface waters from municipal and industrial facilities in six major regions of the United States for 1992, 1997, and 2002. Concentration and effluent flow data were examined for approximately 118,250 facilities in 45 states and the District of Columbia. Inconsistent and incomplete discharge locations, effluent flows, and effluent nutrient concentrations limited the use of these data for calculating nutrient loads. More concentrations were reported for major facilities, those discharging more than 1 million gallons per day, than for minor facilities, and more concentrations were reported for TP than for TN. Analytical methods to check and improve the quality of the Permit Compliance System data were used. Annual loads were calculated using "typical pollutant concentrations" to supplement missing concentrations based on the type and size of facilities. Annual nutrient loads for over 26,600 facilities were calculated for at least one of the three years. Sewage systems represented 74% of all TN loads and 58% of all TP loads. This work represents an initial set of data to develop a comprehensive and consistent national database of point-source nutrient loads. These loads can be used to inform a wide range of water-quality management, watershed modeling, and research efforts at multiple scales.

Journal of the American Water Resources Associatio↗

USGS1979

Weights of lesser snow geese taken on their winter range

Geese are assumed to accumulate fat on the winter range (Bent 1962, Williams 1967) to sustain them through the long northward migration and early part of the nesting season. However, there are no weights given in the literature of lesser snow geese ( Anser c. caerulescens ) on their winter ranges to compare with weights on the breeding grounds. For many years biologists relied on Kortright (1942) for weights of lesser snow geese, and more recently on Bellrose (1976). In the present study, snow geese from the Garwood Prairie, a rice growing area in Colorado County, Texas, were weighed to determine if weights increased before northward migration. The Garwood Prairie is a segment of the snow goose winter range near the Gulf Coast of Texas.

Texas↗