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At least 163 records · Page 9Linked to original sources
USGS2011

Use of non-alpine anthropogenic habitats by American pikas ( Ochotona princeps ) in western Oregon, USA

The American pika ( Ochotona princeps Richardson) has long been characterized in field guides and popular literature as an obligate inhabitant of alpine talus and as having relatively low dispersal capability. However, recent work reveals pikas to have broader habitat associations than previously reported. Over a large portion of the western slope of the Cascade Range in Oregon, pikas inhabit relatively low-elevation sites far from alpine areas and frequently occur in rocky man-made habitats such as roadcuts or rock quarries. We present observations of pikas in these previously overlooked habitats and discuss implications for (1) the proposed listing of the American pika as an endangered or threatened species; (2) furthering our understanding of pika population dynamics, habitat associations, and dispersal capabilites; and (3) management of federal, state, and private forest lands.

Oregon↗
USGS2019

Left out in the rain: Comparing productivity of two associated species exposes a leak in the umbrella species concept

Multi-species approaches to wildlife management have become commonplace and purport to benefit entire biological communities. These strategies aim to manage different, often taxonomically distant species under a single regime based on shared habitat associations and/or co-occurrence in the landscape. We tested the efficacy of multi-species management in the context of creating and maintaining early-successional forest cover types using two species of migratory birds that breed in eastern North America and are each the focus of intensive, concurrent, and overlapping management. American woodcock ( Scolopax minor ) and golden-winged warblers ( Vermivora chrysoptera ) breed in similar diverse-forest landscapes. Each species purportedly benefits from management for the other species and both are often used as flagship species for the creation of young forest and the conservation of associated avian communities. However, the landscape-species relationships that drive reproductive success and population stability in these species have not been explicitly compared. Here, we use previously published spatially-explicit models of productivity (the number of juveniles raised to a biologically significant milestone) to identify the relationship(s) between productivity of American woodcock and golden-winged warblers across a shared landscape. We found productivity to be negatively associated between these species on the same landscape at all spatial scales we modelled (1 m 2 –100 ha). Our results suggest that, with regards to productivity, American woodcock and golden-winged warblers have opposing relationships with the composition of the landscapes in which they coexist and therefore should not be assumed to benefit similarly from any individual management action at any relevant spatial scale.

Biological Conservation↗
USGS2004

Oak-black bear relationships in southeastern uplands

Bears ( Ursus americanus ) primarily occur in upland habitats in the Southeast because uplands were the last to be developed for agriculture and were more likely to become publicly owned. National parks and forests created in the early to mid-1900s served as sources to supply surrounding uplands with bears. Bears could not survive in southeastern uplands without oak mast. Bear reproductive and mortality rates in the region have been shown to be directly linked with acorn production. Masting is thought to be an adaptation by oaks to satiate predators during good acorn years, thus ensuring that the remainder will germinate. Acorn predator populations, however, cannot respond numerically to increased acorn production because the masting is episodic and synchronous. Consequently, bears have developed physiological, behavioral, and ecological adaptations to cope with such food shortages. Despite such adaptations, upland hardwood forests in the Southeast are of lower quality than they once were. The loss of the American chestnut ( Castanea dentata ), higrading, and soil degradation have markedly decreased the carrying capacity for bears and other wildlife. Other changes such as recent forest management practices, forest fragmentation, invasion by the gypsy moth ( Lymantria dispar ), and oak decline threaten to further degrade the capability of southeastern uplands to support bears.

Report↗
USGS2009

Presettlement and modern disturbance regimes in coast redwood forests: Implications for the conservation of old-growth stands

Coast redwood ( Sequoia sempervirens ), a western North American conifer of ancient lineage, has a paradoxical combination of late-successional characteristics and strong adaptations to disturbance. Despite its shade tolerance and heavy dominance of the canopy on many sites, redwood saplings are uncommon in upland old-growth stands. Information needed to ensure the conservation of old-growth redwood forests has been limited. In this review paper, we integrate evidence on redwood biology with data on the historic and modern disturbance regimes to help clarify the degree to which key attributes of redwood forests may have been dependent upon periodic disturbance. Available evidence suggests that episodes of fire, flooding, and slope failure prior to European settlement were frequent but predominantly of low to moderate severity and extent, resulting in broadly uneven-aged forests. The majority of fires prior to European settlement were apparently of human origin. Frequency and severity of the major disturbance agents have been radically changed in modern times. Fires have been largely excluded, and flooding has been altered in ways that have often been detrimental to old-growth redwoods on alluvial terraces. However, because of the apparent anthropogenic origin of most presettlement fires, the long-term evolutionary role of fire for coast redwood is ecologically ambiguous. With fire exclusion, redwood possibly could be displaced to some extent on upland sites by increasing abundance of fire-sensitive competitors. Alternatively, redwood may be able to maintain dominance by vegetative sprouting and new seedling establishment on root-wad mounds, fallen logs, and on soil exposed by slope failure. Future research priorities are suggested that will help resolve some of the current ambiguities.

Forest Ecology and Management↗
USGS2024

An experimental study of benthic habitat selection in yellow-phase American eels (Anguilla rostrata)

In a laboratory experiment, we quantified microhabitat use of small yellow-phase American eels ( Anguilla rostrata , n = 130, 224–338 mm TL) conditional on five benthic substrate types common to rivers within their geographic range. During nine, 4-day trials replicated with three aquaria, American eels were given a choice to burrow into five equally available benthic substrates: cobble (90–256 mm), gravel (4–16 mm), sand (0.125–1 mm), silt/clay (< 0.0625 mm), and leaf pack. Five American eels were used per aquarium for each trial, and individuals were used one time only. All eels were injected with PIT tags prior to the study, which allowed for determination of lengths and otolith-based ages of each individual following each trial. Leaf pack was selected with a significantly higher probability than other substrates (63 of 130 individuals). However, other substrates were also used (cobble, 21 of 130; silt/clay, 18 of 130; gravel, 16 of 130; and sand, 12 of 130). Length and age covariates were not associated with substrate selection. Selection of leaf pack habitat supports the importance of forested riparian zones and terrestrial organic material to yellow-phase American eels in riverine systems.

West Virginia↗
USGS2007

Occurrence and nest survival of four thrush species on a managed central Appalachian forest

The wood thrush (Hylocichla mustelina Gmelin) is a species of concern in the central Appalachians, and is sympatric there with three related species, the American robin (Turdus migratorius Linnaeus), hermit thrush (Catharus guttatus Pallas), and veery (Catharus fuscescens Stephens). Our objectives were to quantify use of mature forests and areas subjected to even-aged harvesting and partial harvesting by these four species by measuring their frequency of occurrence, nest survival, and nest site characteristics. We also compared microhabitat characteristics among the landcover types. During 2001-2003 we conducted point count surveys, monitored nests, and collected nest habitat data on a managed forest in West Virginia. Land cover was digitized into five categories: deciduous and mixed mature forest, deciduous and mixed partial harvest, and even-aged regeneration harvest. Chi-square goodness-of-fit analysis with Bonferroni 95% confidence intervals indicated that deciduous partial harvests were more likely to be inhabited by wood thrushes. The other three species were less likely to occur in deciduous partial harvests, and veery had lower nest survival in partial harvests than in mature forest. Contrary to many published descriptions that suggest thrushes will not nest in even-aged harvests, a small number of all species but hermit thrushes did nest in this cover type, often near a residual canopy tree. Hermit thrushes were less likely to inhabit mature deciduous forest, even-aged harvests, and harvested edges but chose nesting areas in mature mixed forest that was disturbed by road building and the seeding of landings and skid trails >10 years ago. Microhabitat characteristics of landcovers did not differ overall. Our results suggest a relationship with partial harvesting that is positive for wood thrush but negative for the other three species. ?? 2007 Elsevier B.V. All rights reserved.

Forest Ecology and Management↗
USGS2016

Seeing the forest through the trees: Considering roost-site selection at multiple spatial scales

Conservation of bat species is one of the most daunting wildlife conservation challenges in North America, requiring detailed knowledge about their ecology to guide conservation efforts. Outside of the hibernating season, bats in temperate forest environments spend their diurnal time in day-roosts. In addition to simple shelter, summer roost availability is as critical as maternity sites and maintaining social group contact. To date, a major focus of bat conservation has concentrated on conserving individual roost sites, with comparatively less focus on the role that broader habitat conditions contribute towards roost-site selection. We evaluated roost-site selection by a northern population of federally-endangered Indiana bats ( Myotis sodalis ) at Fort Drum Military Installation in New York, USA at three different spatial scales: landscape, forest stand, and individual tree level. During 2007&ndash;2011, we radiotracked 33 Indiana bats (10 males, 23 females) and located 348 roosting events in 116 unique roost trees. At the landscape scale, bat roost-site selection was positively associated with northern mixed forest, increased slope, and greater distance from human development. At the stand scale, we observed subtle differences in roost site selection based on sex and season, but roost selection was generally positively associated with larger stands with a higher basal area, larger tree diameter, and a greater sugar maple ( Acer saccharum ) component. We observed no distinct trends of roosts being near high-quality foraging areas of water and forest edges. At the tree scale, roosts were typically in American elm ( Ulmus americana ) or sugar maple of large diameter (>30 cm) of moderate decay with loose bark. Collectively, our results highlight the importance of considering day roost needs simultaneously across multiple spatial scales. Size and decay class of individual roosts are key ecological attributes for the Indiana bat, however, larger-scale stand structural components that are products of past and current land use interacting with environmental aspects such as landform also are important factors influencing roost-tree selection patterns.

PLoS ONE↗
USGS2018

Ecosystems science: Genes to landscapes

Bountiful fisheries, healthy and resilient wildlife, flourishing forests and vibrant grasslands are coveted resources that benefit all Americans. U.S. Geological Survey (USGS) science supports the conservation and management of the Nation’s fish and wildlife, and the landscapes they inhabit. Our biological resources—ecosystems and the wild things that live in them—are the foundation of our conservation heritage and an economic asset to current and future generations of Americans. The USGS Ecosystems Mission Area, the biological research arm of the Department of the Interior (DOI), provides science to help America achieve sustainable management and conservation of its biological resources. This work is done within the broader mission of the USGS—to serve the Nation with science that advances understanding of our natural resources, informs land and water stewardship, and helps safeguard communities from natural and environmental hazards. The Ecosystems Mission Area provides research, technical assistance, and education conducted by Cooperative Research Units and Science Centers located in nearly every State. The quality of life and economic strength in America hinges on healthy ecosystems that support living things and natural processes. Ecosystem science better enables society to understand how and why ecosystems change and to guide actions that can prevent damage to, and restore and sustain ecosystems. It is through this knowledge that informed decisions are made about natural resources that can enhance our Nation’s economic and environmental well-being.

Fact Sheet↗
USGS1992

Comparison of neotropical migrant landbird populations wintering in tropical forest, isolated forest fragments, and agricultural habitats

Neotropical migrant bird populations were sampled at 76 sites in seven countries by using mist nets and point counts during a six-winter study. Populations in major agricultural habitats were compared with those in extensive forest and isolated forest fragments. Certain Neotropical migrants, such as the Northern Parula, American Redstart, and the Black-throated Blue, Magnolia, Black-and-white, and Hooded warblers, were present in arboreal agricultural habitats such as pine, cacao, citrus, and shade coffee plantations in relatively large numbers. Many north temperate zone shrub-nesting species, such as the Gray Catbird, White-eyed Vireo, Tennessee Warbler, Common Yellowthroat, and Indigo Bunting, also used agricultural habitats in winter, as did resident hummingbirds and migrant orioles. Ground-foraging migrants, such as thrushes and Kentucky Warblers, were rarely found in the agricultural habitats sampled. Although many Neotropical migrants use some croplands, this use might be severely limited by overgrazing by cattle, by intensive management (such as removal of ground cover in an orchard), or by heavy use of insecticides, herbicides, or fungicides.

Book chapter↗
USGS2005

Effects of landscape change on fish assemblage structure in a rapidly growing metropolitan area in North Carolina, USA

We evaluated a comprehensive set of natural and land-use attributes that represent the major facets of urban development at fish monitoring sites in the rapidly growing Raleigh-Durham, North Carolina metropolitan area. We used principal component and correlation analysis to obtain a nonredundant subset of variables that extracted most variation in the complete set. With this subset of variables, we assessed the effect of urban growth on fish assemblage structure. We evaluated variation in fish assemblage structure with nonmetric multidimensional scaling (NMDS). We used correlation analysis to identify the most important environmental and landscape variables associated with significant NMDS axes. The second NMDS axis is related to many indices of land-use/land-cover change and habitat. Significant correlations with proportion of largest forest patch to total patch size (r = -0.460, P < 0.01), diversity of patch types (r = 0.554, P < 0.001), and population density (r = 0.385, P < 0.05) helped identify NMDS axis 2 as a disturbance gradient. Positive and negative correlations between the abundance of redbreast sunfish Lepomis auritus and bluehead chub Nocomis leptocephalus, respectively, and NMDS axis 2 also were evident. The North Carolina index of biotic integrity and many of its component metrics were highly correlated with urbanization. These results indicate that aquatic ecosystem integrity would be optimized by a comprehensive integrated management strategy that includes the preservation of landscape function by maximizing the conservation of contiguous tracts of forested lands and vegetative cover in watersheds. ?? 2005 by the American Fisheries Society.

American Fisheries Society Symposium↗
USGS2017

Combined analysis of roadside and off-road breeding bird survey data to assess population change in Alaska

Management interest in North American birds has increasingly focused on species that breed in Alaska, USA, and Canada, where habitats are changing rapidly in response to climatic and anthropogenic factors. We used a series of hierarchical models to estimate rates of population change in 2 forested Bird Conservation Regions (BCRs) in Alaska based on data from the roadside North American Breeding Bird Survey (BBS) and the Alaska Landbird Monitoring Survey, which samples off-road areas on public resource lands. We estimated long-term (1993–2015) population trends for 84 bird species from the BBS and short-term (2003–2015) trends for 31 species from both surveys. Among the 84 species with long-term estimates, 11 had positive trends and 17 had negative trends in 1 or both BCRs; negative trends were primarily found among aerial insectivores and wetland-associated species, confirming range-wide negative continental trends for many of these birds. Three species with negative trends in the contiguous United States and southern Canada had positive trends in Alaska, suggesting different population dynamics at the northern edges of their ranges. Regional population trends within Alaska differed for several species, particularly those represented by different subspecies in the 2 BCRs, which are separated by rugged, glaciated mountain ranges. Analysis of the roadside and off-road data in a joint hierarchical model with shared parameters resulted in improved precision of trend estimates and suggested a roadside-related difference in underlying population trends for several species, particularly within the Northwestern Interior Forest BCR. The combined analysis highlights the importance of considering population structure, physiographic barriers, and spatial heterogeneity in habitat change when assessing patterns of population change across a landscape as broad as Alaska. Combined analysis of roadside and off-road survey data in a hierarchical framework may be particularly useful for evaluating patterns of population change in relatively undeveloped regions with sparse roadside BBS coverage.

Condor↗
USGS2011

Seeing the forest and the trees: USGS scientist links local changes to global scale

The recent recipient of two major awards, Craig D. Allen, a research ecologist with the U.S. Geological Survey Fort Collins Science Center, has loved trees since childhood. He is now considered an expert of world renown on the twin phenomena of forest changes and tree mortality resulting from climate warming and drought, and in 2010 was twice recognized for his scientific contributions. In December 2010, Dr. Allen was named a 2010 Fellow of the American Association for the Advancement of Science “for outstanding leadership in the synthesis of global forest responses to climate change, built from worldwide collaboration and a deep understanding of the environmental history of the southwestern United States.” In March 2010, he was honored with the Meritorious Service Award from the U.S. Department of the Interior (DOI) in recognition of his outstanding vision, initiative, and scientific contributions to the USGS, DOI, and U.S. Department of Agriculture in establishing a model science program to support adaptive land management at the new Valles Caldera National Preserve in north-central New Mexico. Dr. Allen has authored more than 85 publications on landscape ecology and landscape change, from fire history and ecology to ecosystem responses to climate change. He has appeared on NOVA discussing fire ecology and on The Discovery Channel and Discovery Canada explaining the links between drought-induced tree mortality and climate warming, in addition to being interviewed and quoted in innumerable newspaper articles on both topics. But how did this unassuming scientist grow from nurturing maple saplings on 40 acres in Wisconsin to understanding forest system stress worldwide?

Report↗
USGS2013

Response of brown-headed cowbirds and three host species to thinning treatments in low-elevation ponderosa pine forests along the northern Colorado Front Range

Thinning ponderosa pine ( Pinus ponderosa ) forests to achieve desired ecological conditions remains a priority in the North American west. In addition to reducing the risk of high-severity wildfires in unwanted areas, stand thinning may increase wildlife and plant diversity and provide increased opportunity for seedling recruitment. We initiated conservative (i.e. minimal removal of trees) ponderosa stand thinning treatments with the goals of reducing fire risk and improving habitat conditions for native wildlife and flora. We then compared site occupancy of brown-headed cowbirds ( Molothrus ater ), chipping sparrows ( Spizella passerina ), plumbeous vireos ( Vireo plumbeus ), and western wood-pewees ( Contopus sordidulus ) in thinned and unthinned (i.e., control) forest stands from 2007 to 2009. Survey stations located in thinned stands had 64% fewer trees/ha, 25% less canopy cover, and 23% less basal area than stations in control stands. Occupancy by all three host species was negatively associated with tree density, suggesting that these species respond favorably to forest thinning treatments in ponderosa pine forests. We also encountered plumbeous vireos more frequently in plots closer to an ecotonal (forest/grassland) edge, an association that may increase their susceptibility to edge-specialist, brood parasites like brown-headed cowbirds. Occupancy of brown-headed cowbirds was not related to forest metrics but was related to occupancy by plumbeous vireos and the other host species in aggregate, supporting previous reports on the affiliation between these species. Forest management practices that promote heterogeneity in forest stand structure may benefit songbird populations in our area, but these treatments may also confer costs associated with increased cowbird occupancy. Further research is required to understand more on the complex relationships between occupancy of cowbirds and host species, and between cowbird occupancy and realized rates of nest parasitism.

Colorado↗
USGS2013

Do singing-ground surveys reflect american woodcock abundance in the western Great Lakes region?

The Singing-ground Survey (SGS) is the primary monitoring tool used to assess population status and trends of American woodcock ( Scolopax minor ). Like most broad-scale surveys, the SGS cannot be directly validated because there are no independent estimates of abundance of displaying male American woodcock at an appropriate spatial scale. Furthermore, because locations of individual SGS routes have generally remained stationary since the SGS was standardized in 1968, it is not known whether routes adequately represent the landscapes they were intended to represent. To indirectly validate the SGS, we evaluated whether 1) counts of displaying male American woodcock on SGS routes related to land-cover types known to be related to American woodcock abundance, 2) changes in counts of displaying male American woodcock through time were related to changes in land cover along SGS routes, and 3) land-cover type composition along SGS routes was similar to land-cover type composition of the surrounding landscape. In Wisconsin and Minnesota, USA, counts along SGS routes reflected known American woodcock-habitat relations. Increases in the number of woodcock heard along SGS routes over a 13-year period in Wisconsin were related to increasing amounts of early successional forest, decreasing amounts of mature forest, and increasing dispersion and interspersion of cover types. Finally, the cover types most strongly associated with American woodcock abundance were represented along SGS routes in proportion to their composition of the broader landscape. Taken together, these results suggest that in the western Great Lakes region, the SGS likely provides a reliable tool for monitoring relative abundance and population trends of breeding, male American woodcock.

Minnesota, Wisconsin↗
USGS2009

Channel, floodplain, and wetland responses to floods and overbank sedimentation, 1846-2006, Halfway Creek Marsh, Upper Mississippi Valley, Wisconsin

Conversion of upland forest and prairie vegetation to agricultural land uses, following Euro-American settlement in the Upper Mississippi River System, led to accelerated runoff and soil erosion that subsequently transformed channels, floodplains, and wetlands on bottomlands. Halfway Creek Marsh, at the junction of Halfway Creek and the Mississippi River on Wisconsin's western border, is representative of such historical transformation. This marsh became the focus of a 2005-2006 investigation by scientists from the U.S. Geological Survey, the University of Wisconsin- Madison, and the U.S. Environmental Protection Agency, who used an understanding of the historical transformation to help managers identify possible restoration alternatives for Halfway Creek Marsh. Field-scale topographic surveys and sediment cores provided data for reconstructing patterns and rates of historical overbank sedimentation in the marsh. Information culled from historical maps, aerial photographs, General Land Offi ce Survey notes, and other historical documents helped establish the timing of anthropogenic disturbances and document changes in channel patterns. Major human disturbances, in addition to agricultural land uses, included railroad and road building, construction of artifi cial levees, drainage alterations, and repeated dam failures associated with large floods. A volume of approximately 1,400,000 m 3 , involving up to 2 m of sandy historical overbank deposition, is stored through the upper and lower marshes and along the adjacent margins of Halfway Creek and its principal tributary, Sand Lake Coulee. The estimated overbank sedimentation rate for the entire marsh is ??3,000 m 3 yr- 1 for the recent period 1994-2006. In spite of reduced surface runoff and soil erosion in recent years, this recent sedimentation rate still exceeds by ??4 times the early settlement (1846-1885) rate of 700 m 3 yr- 1 , when anthropogenic acceleration of upland surface runoff and soil erosion was beginning. The highest rate of historical bottomland sedimentation occurred from 1919 to 1936, when the estimated overbank sedimentation rate was 20,400 m 3 yr- 1 . This rate exceeded by nearly 30 times the 1846-1886 rate. Artifi cial levees were constructed along the upper reach of Halfway Creek in the marsh during the early twentieth century to restrict fl ooding on the adjacent bottomlands. Anomalously high overbank sedimentation rates subsequently occurred on the fl oodplain between the levees, which also facilitated more effi cient transport of sediment into the lower marsh bottomland. Although overbank sedimentation rates dropped after 1936, corresponding to the widespread adoption of soil-conservation and agricultural best-management practices, the continuation of anomalously high overbank sedimentation between the levees led to increased bank heights and development of a relatively deep channel. The deep cross-section morphology is commonly mistaken as evidence of channel incision; however, this morphology actually resulted from excessive overbank sedimentation. The historical metamorphosis of the Halfway Creek channel and riparian wetlands underscores the importance of understanding the long-term history of channel and fl oodplain evolution when restoration of channels and riparian wetlands are under consideration. Sedimentation patterns and channel morphology for Halfway Creek Marsh probably are representative of other anthropogenically altered riparian wetlands in the Upper Mississippi River System and similar landscapes elsewhere.

Special Paper of the Geological Society of America↗