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Results for “Valley Habitats”

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At least 109 records · Page 6Linked to original sources
USGS2017

Yolo Bypass Juvenile Salmon Utilization Study 2016—Summary of acoustically tagged juvenile salmon and study fish release, Sacramento River, California

The Yolo Bypass is a flood control bypass in Sacramento Valley, California. Flood plain habitats may be used for juvenile salmon rearing, however, the potential value of such habitats can be difficult to evaluate because of the intermittent nature of inundation events. The Yolo Bypass Juvenile Salmon Utilization Study (YBUS) used acoustic telemetry to evaluate the movements and survival of juvenile salmon adjacent to and within the Yolo Bypass during the winter of 2016. This report presents numbers, size data, and release data (times, dates, and locations) for the 1,197 acoustically tagged juvenile salmon released for the YBUS from February 21 to March 18, 2016. Detailed descriptions of the surgical implantation of transmitters are also presented. These data are presented to support the collaborative, interagency analysis and reporting of the study findings.

California↗
USGS2022

A review of Arctomecon californica (Papaveraceae) with a focus on the species’ potential for propagation and reintroduction and conservation needs

Las Vegas bearpoppy ( Arctomecon californica ) occurrences have fluctuated during the past several decades, in part due to interannual variability in rainfall that influences recruitment and mortality events; yet, development in the Las Vegas Valley continues to threaten habitat supporting this species. Arctomecon californica was petitioned for listing under the Endangered Species Act in 2019 and is currently under review to determine whether listing is warranted ( USFWS 2020 ). This review updates species information for A. californica and includes recent insights into the species' seed ecology, habitat requirements and suitability models, propagation and reintroduction, and pollinator biology. We include information from the past 20 years in these areas that supplement conservation and restoration actions for the species. We also identify topics with scarce information and highlight areas for future study, including the following: preservation of genetic diversity through germplasm collections, identification of mechanisms driving the species' soil endemism, maintenance of A. californica –pollinator relationships through understanding pollinator habitat, determination of the viable seed fraction and its longevity in the soil seed reserves, and prediction of population response to regional climate change based on demographic modeling.

Arizona, Nevada↗
USGS2023

An agent-based model to quantify energetics, movement and habitat selection of mid-continent mallards in the Mississippi Alluvial Valley

The dynamics of wintering waterfowl populations at the landscape scale are the result of complex interactions of environmental, behavioral and energetic drivers. Agent-based models provide a method to directly link these factors in a spatially explicit framework and allow the emergence of patterns from the aggregation of individual agent actions. We adapted the Spatially-explicit Waterbird Agent-based Model Program (SWAMP), originally developed for waterfowl in central California, to simulate a basin-scale population of mallards ( A. platyrhynchos ) wintering in the Mississippi Alluvial Valley over a four-month period (November–February). Simulated agents move within the landscape, foraging on areas made available based on a probabilistic inundation status, and converting food resources to endogenous energy. The model uses a high-resolution map of eastern Arkansas waterfowl habitats and incorporates a hierarchical habitat selection system that enables mallards to relocate at increasing scales in response to changing food availability. We validated the performance of modeled mallard body condition and behavioral metrics under a range of environmental conditions against expected outcomes derived from empirical data and found that the simulation produced realistic representations of changes in flight distances, energy expenditure, lipid storage, and foraging habitat use in response to depleting food resources over time. We discuss the model's applicability as a tool to quantify waterfowl response to a range of environmental conditions and to evaluate scenarios of landscape composition and configuration in the context of waterfowl population management.

Ecological Modelling↗
USGS2001

Habitat evaluation using GIS a case study applied to the San Joaquin Kit Fox

Concern over the fate of plant and animal species throughout the world has accelerated over recent decades. Habitat loss is considered the main culprit in reducing many species' abundance and range, leading to numerous efforts to plan and manage habitat preservation. Our work uses Geographic Information Systems (GIS) data and modeling to define a spatially explicit analysis of habitat value, using the San Joaquin Kit Fox (Vulpes macrotis mutica) of California (USA) as an example. Over the last 30 years, many field studies and surveys have enhanced our knowledge of the life history, behavior, and needs of the kit fox, which has been proposed as an umbrella or indicator species for grassland habitat in the San Joaquin Valley of California. There has yet been no attempt to convert much of this field knowledge into a model of spatial habitat value useful for planning purposes. This is a significant omission given the importance and visibility of the imperiled kit fox and increasing trends toward spatially explicit modeling and planning. In this paper we apply data from northern California to derive a small-cell GIS raster of habitat value for the kit fox that incorporates both intrinsic habitat quality and neighborhood context, as well the effects of barriers such as roads. Such a product is a useful basis for assessing the presence and amounts of good (and poor) quality habitat and for eventually constructing GIS representations of viable animal territories that could be included in future reserves. ?? 2001 Elsevier Science B.V.

Landscape and Urban Planning↗
USGS2010

Movement distances and habitat switching by female Mallards wintering in the Lower Mississippi Alluvial Valley

Mallard (Anus platyrhynchos) populations in the Lower Mississippi Alluvial Valley (hereafter, LMAV) comprise the largest concentration of wintering Mallards in North America. Radiotelemetry techniques were employed to assess movements by female Mallards during winters of 2004-2005 and 2005-2006; 467 paired (diurnal and nocturnal) observations on 80 radiomarked females were attained to assess effects of date, female age, hunting regime and habitat type on distances moved and potential habitat switching. Distance moved increased with date for females diurnally located in RICE but decreased for females in FOREST. Median movement distance was 1.5 km, suggesting suitable habitats for all activities were in close proximity. Habitat switching varied among diurnal habitat types used by females. Females diurnally located in FOREST and REFOR switched habitats in <= 22% of paired observations, whereas females diurnally located in RICE switched habitats in 55% of paired observations. The decreased movement distances and less frequent habitat switching by females using forested habitats should reduce their energy expenditure and exposure to predation risk. The results document the importance of forested wet-lands to Mallards wintering in the LMAV and provide support for programs that protect and restore such habitats. Received 18 November 2009, accepted 16 January 2010.

Lousiana↗
USGS2000

Development of management objectives for breeding birds in the Mississippi Alluvial Valley

We used a six-step process to set habitat objectives and population goals for breeding birds in the Mississippi Alluvial Valley. Specifically, we used existing empirical studies and mathematically derived viable population estimates to define habitat objectives and population goals for bottomland hardwood forest, the most important habitat type in this physiographic area. Although habitat objectives must address both quality and quantity, we concentrate here on the size and number of forest patches in this highly fragmented landscape. To support source populations of all forest breeding birds we recommend the protection/restoration of 52 forest patches that are 4,000-8,000 ha in size, 36 patches of 8,000-40,000 ha, and 13 patches greater than 40,000 ha. Although every physiographic area is unique, the methodology applied here should be applicable in other situations.

Book chapter↗
USGS2019

The importance of turtle populations to wetland restoration in the upper Mississippi embayment of the Mississippi Alluvial Valley

The Upper Mississippi Embayment (UME) ecoregion covers approximately 141,895 km2 and historically supported 9,712,455 ha of bottomland deciduous forests, swamps, bayous, and rivers. Only about 500 ha (< 0.01%) of pre-settlement bottomland hardwood forest habitat in the Mississippi Alluvial Valley (MAV) in the UME remained by the 1940s because the timber was clearcut and the wetlands drained for agriculture. By 1983 only a few scattered cypress-tupelo swamps remained. We studied the freshwater turtle community in Allred Lake, Missouri, a rare remnant of this ecosystem and compared these results to those from two other study sites in the MAV, Big Oak Tree State Park (BOTSP), Missouri, and Coldwater River National Wildlife Refuge (CRNWR), Mississippi. Species richness included six species commonly found throughout the MAV. One species (Red-eared Slider, Trachemys scripta elegans) dominated density and biomass in all three assemblages. The occurrence of the six species we studied in man-made restored wetlands such as those in BOTSP and CRNWR indicate these turtles would adapt to restored wetlands in the MAV in southeastern Missouri and elsewhere in the ecosystem. We provide information on habitat features that could be included in restoration design and construction that would benefit turtles. Given the ongoing worldwide decline of turtles, consideration of turtle ecology and behavior in wetland restoration projects in the MAV may be warranted.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗
USGS2021

Northern bobwhite occupancy patterns on multiple spatial scales across Arkansas

Northern bobwhite Colinus virginianus populations have been rapidly declining in the eastern, central, and southern United States for decades. Land use change and an incompatibility between northern bobwhite resource needs and human land use practices have driven declines. Here, we applied occupancy analyses on two spatial scales (state level and ecoregion level) to more than 5,000 northern bobwhite surveys conducted over 6 y across the entire state of Arkansas to explore patterns in occupancy and land use variables, and to identify priority areas for management and conservation. At the state level, northern bobwhite occupied 29% of sites and northern bobwhite were most likely to occur in areas with a high percentage of early successional habitat (grassland, pasture, and shrubland). The statewide model predicted that northern bobwhite were likely to occur (≥ 75% predicted occupancy) in < 20% of the state. Arkansas is comprised of five distinct ecoregions, and analyses at the ecoregion spatial scale showed that habitat associations of northern bobwhite could vary between ecoregions. For example, early successional habitat best predicted northern bobwhite occupancy in both the Arkansas River Valley and Ozark Mountains ecoregions, and other habitat associations such as the proportion of herbaceous habitat and hay-pasture habitat, respectively, further refined predictions. Contrastingly, richness of land cover classes alone best predicted northern bobwhite occupancy in the Ouachita Mountains ecoregion. Ecoregion-level models were thus more discerning than the state-level model and should be more helpful to managers in identifying priority conservation areas. However, in two of five ecoregions, surveys too rarely encountered northern bobwhite to accurately predict their occurrence. We found that likely occupied northern bobwhite habitat lay primarily on private properties (95%), but that numerous public entities own and manage land identified as suitable or likely occupied. We conclude that management of northern bobwhite in Arkansas could benefit from cooperation among state, federal, and military partners, as well as surrounding private landowners and that ecoregion-specific models may be more useful in identifying priority areas for management. Our approach incorporates multiple landscape scales when using remote sensing technology in conjunction with monitoring data and could have important application for the management of northern bobwhite and other grassland bird species.

Arkansas↗
USGS2016

Increased body mass of ducks wintering in California's Central Valley

Waterfowl managers lack the information needed to fully evaluate the biological effects of their habitat conservation programs. We studied body condition of dabbling ducks shot by hunters at public hunting areas throughout the Central Valley of California during 2006&ndash;2008 compared with condition of ducks from 1979 to 1993. These time periods coincide with habitat increases due to Central Valley Joint Venture conservation programs and changing agricultural practices; we modeled to ascertain whether body condition differed among waterfowl during these periods. Three dataset comparisons indicate that dabbling duck body mass was greater in 2006&ndash;2008 than earlier years and the increase was greater in the Sacramento Valley and Suisun Marsh than in the San Joaquin Valley, differed among species (mallard [ Anas platyrhynchos ], northern pintail [ Anas acuta ], America wigeon [ Anas americana ], green-winged teal [ Anas crecca ], and northern shoveler [ Anas clypeata ]), and was greater in ducks harvested late in the season. Change in body mass also varied by age&ndash;sex cohort and month for all 5 species and by September&ndash;January rainfall for all except green-winged teal. The random effect of year nested in period, and sometimes interacting with other factors, improved models in many cases. Results indicate that improved habitat conditions in the Central Valley have resulted in increased winter body mass of dabbling ducks, especially those that feed primarily on seeds, and this increase was greater in regions where area of post-harvest flooding of rice and other crops, and wetland area, has increased. Conservation programs that continue to promote post-harvest flooding and other agricultural practices that benefit wintering waterfowl and continue to restore and conserve wetlands would likely help maintain body condition of wintering dabbling ducks in the Central Valley of California.

California↗
USGS2008

Relating streamflow characteristics to specialized insectivores in the Tennessee River Valley: a regional approach

Analysis of hydrologic time series and fish community data across the Tennessee River Valley identified three hydrologic metrics essential to habitat suitability and food availability for insectivorous fish communities in streams of the Tennessee River Valley: constancy (flow stability or temporal invariance), frequency of moderate flooding (frequency of habitat disturbance), and rate of streamflow recession. Initial datasets included 1100 fish community sites and 300 streamgages. Reduction of these datasets to sites with coexisting data yielded 33 sites with streamflow and fish community data for analysis. Identification of critical hydrologic metrics was completed using a multivariate correlation procedure that maximizes the rank correlation between the hydrologic metrics and fish community resemblance matrices. Quantile regression was used to define thresholds of potential ranges of insectivore scores for given values of the hydrologic metrics. Increased values of constancy and insectivore scores were positively correlated. Constancy of streamflow maintains wetted perimeter, which is important for providing habitat for fish spawning and increased surface area for invertebrate colonization and reproduction. Site scores for insectivorous fish increased as the frequency of moderate flooding (3 times the median annual streamflow) decreased, suggesting that insectivorous fish communities respond positively to less frequent disturbance and a more stable habitat. Increased streamflow recession rates were associated with decreased insectivore scores. Increased streamflow recession can strand fish in pools and other areas that are disconnected from flowing water and remove invertebrates as food sources that were suspended during high-streamflow events.

Tennessee↗
USGS2000

Development of management objectives for waterfowl and shorebirds within the Mississippi Alluvial Valley

The goal of the Lower Mississippi Valley Joint Venture of the North American Waterfowl Management Plan is to provide sufficient habitat to support 4.3 million wintering ducks and 1.0 million wintering geese annually. Under the assumption that the amount of foraging habitat is the primary limitation to supporting waterfowl population goals in the Mississippi Alluvial Valley (MAV), a habitat objective to make available 285,000 ha of waterfowl foraging habitat is divided among seven states. This habitat objective is further divided between public and private ownership and among three habitat types: Bottomland hardwood forest, moist-soil sites, and agricultural fields. Management objectives for shorebirds within the MAV which provide foraging habitat for 0.5 million shorebirds during their southward migration have been tentatively established. Several as yet unverified assumptions were used in establishing these objectives; consequently, we caution that the objectives are subject to revision as the assumptions are tested. We assumed that 0.5 million shorebirds move through the MAV during late summer and fall, each foraging for an average of 10 days. During this migration period, foraging shorebirds are assumed to require sufficient forage to gain 1 g of biomass per day, in addition to their basal metabolic needs. Given an invertebrate food supply that provides 17.6 kj ? g-1, we calculated that an average 45 g shorebird requires about 8 g of invertebrate forage per day. Further assuming that each ha of managed shorebird habitat can provide 20 kg of invertebrate food resources available to shorebirds, we extrapolated a need for 2000 ha of shorebird foraging habitat. We suggest that the bulk of this foraging habitat be provided on public lands and that it be distributed throughout the MAV.

Book chapter↗
USGS2010

Pintail and mallard survival in California relative to habitat, abundance, and hunting

The influence of habitat, waterfowl abundance, and hunting on winter survival of waterfowl is not well understood. We studied late August-March survival of 163 after-hatch-year (AHY) and 128 hatch-year (HY) female mallards (Anas platyrhynchos) radiotagged in Sacramento Valley (SACV) and 885 AHY female northern pintails (A. acuta) radiotagged throughout the Central Valley of California, USA, relative to flooded habitat (HAB), January abundance of each species (JMAL or JPIN), hunter-days (HDY), and a hunting pressure index (HPI) that combined these variables. From EARLY (1987-1994) to LATE (1998-2000), HAB increased 39%, JPIN increased 45%, JMAL increased 53%, HDY increased 21%, duck-hunting season increased from 59 days to 100 days, and the female daily bag limit doubled to 2 for mallards but remained 1 for pintails. Survival (?? SE) was greater during LATE versus EARLY for pintails radiotagged in each region (SACV: 93.2 ?? 2.1% vs. 87.6 ?? 3.0%; Suisun Marsh: 86.6 ?? 3.2% vs. 77.0 ?? 3.7%; San Joaquin Valley: 86.6 ?? 3.1% vs. 76.9 ?? 4.1%) but not for SACV mallards (AHY: 70.6 ?? 7.2% to 74.4 ?? 7.7% vs. 80.1 ?? 7.2% to 82.8 ?? 5.6%; HY: 48.7 ?? 9.1% [1999-2000 only] vs. 63.5 ?? 8.8% to 67.6 ?? 8.0%). Most pintail (72%) and mallard (91%) deaths were from hunting, and lower HPI and higher JPIN or JMAL were associated with reduced mortality. Increased HAB was associated with reduced winter mortality for pintails but not for SACV mallards. Pintail survival rates that we measured were within the range reported for other North American wintering areas, and during LATE were higher than most, even though our study duration was 68-110 days longer. Winter survival rates of SACV mallards were also within the reported range. However, with higher bag limits and longer seasons, mallard survival during LATE was lower than in most other wintering areas, especially during 1999-2000, when high winds on opening weekend resulted in high hunting mortality. Habitat conservation and favorable agriculture practices helped create a Central Valley wintering environment where natural mortality of mallards and pintails was low and survival varied with hunting mortality. We recommend regulations and habitat management that continue to minimize natural mortality while allowing sustainable harvest at a level that helps maintain strong incentive for management of Central Valley waterfowl habitats, including the large portion that is privately owned.

Journal of Wildlife Management↗
USGS1996

Geographic variation in migratory behavior of greater white-fronted geese ( Anser albifrons )

We studied the migration and winter distribution of adult Greater White-fronted Geese ( Anser albifrons frontalis ) radio-marked on the Yukon-Kuskokwim Delta (YKD) and Bristol Bay Lowlands (BBL) of Alaska from 1987 to 1992. The major autumn staging site for geese from both breeding areas was the Klamath Basin on the California/Oregon border. However, temporal use of this area differed markedly between populations. Geese from the BBL arrived at the Klamath Basin nearly 30 days before geese from the YKD and departed before most YKD geese had arrived. Ninety percent of BBL geese used the Klamath Basin in autumn, whereas 30% of YKD geese bypassed the Klamath Basin during autumn and instead flew directly to the Central Valley of California. Nearly all BBL geese migrated directly from the Klamath Basin to wintering areas in Mexico, bypassing the Central Valley. Ninety percent of the BBL geese wintered in Mexico, as opposed to <20% of the YKD geese. Wetlands of the Interior Highlands in the state of Chihuahua, particularly Laguna Babicora, were used by >90% of the radio-marked geese in Mexico. Marshes along the West Coast comprised the other important wintering habitat in Mexico. The Sacramento Valley of California was the predominant wintering area for YKD geese. BBL geese migrated north from Mexico into the San Joaquin Valley or Sacramento-San Joaquin Delta of California by the last week of January. Fifty-five percent of the BBL population used the Klamath Basin in spring, but many birds staged in eastern Oregon and western Idaho. In contrast, geese from the YKD staged almost exclusively in the Klamath Basin during spring before flying to staging areas in Alaska. Breeding allopatry and temporal partitioning on staging and wintering areas likely has contributed to the evolution of previously described phenotypic differences between these populations. These two populations, along with the Tule Greater White-fronted Goose (A. a. gambeli), may constitute a portion of a Rassenkreis, a group of subspecies connected by clines, each ecotype of which has independent conservation needs.

The Auk↗
USGS2025

Habitat features influencing waterbird use of managed wetlands enrolled in a public-private partnership for land conservation: The California Waterfowl Habitat Program

Draining, water diversion, and development have greatly reduced the availability of freshwater wetland habitat around the world, and many remaining wetlands are on private lands. Public–private partnership programs can be an important means for promoting habitat conservation and management on private lands. We investigated bird use of 117 wetlands enrolled in the California Waterfowl Habitat Program in California's Central Valley, where two-thirds of wetlands are under private ownership and management. Specifically, we quantified the influence of wetland habitat features and surrounding land cover on waterbird density and diversity in late winter and early spring and during the waterfowl breeding season. Dabbling duck and shorebird densities were highest in wetlands that had water depths < 20 cm, and waterbird densities decreased with water depth. Greater amounts of emergent vegetation, especially tall and dense emergent vegetation, had a negative effect on total waterbird density but a positive effect on species richness and secretive marsh bird density. Shorebird and breeding duck densities were lower in wetlands with a large number of trees and other potential perch sites, and waterbird densities decreased with the amount of nearby wetland habitat on the landscape. Overall, we estimated that during late winter and early spring, private properties that were enrolled in the California Waterfowl Habitat Program (8000–8500 ha each year) supported 480,000 birds per day during extreme drought conditions in 2022 and 280,000 birds per day in more normal, non-drought conditions in 2023. Over the 76-day winter and early spring survey period, this amounted to more than 20 million bird use days on wetlands enrolled in the California Waterfowl Habitat Program during late winter and early spring. These results demonstrate the value of public–private wetland conservation partnerships, the influence of wetland habitat features and surrounding land cover on waterbird abundance, and the benefits of habitat features that could be incorporated into management plans and wetland selection criteria for enrollment into public–private conservation programs.

California↗
USGS2006

Bioindicators from Mosquitofish (Gambusia affinis) Sampled from the Imperial Valley in Southern California

The Sonny Bono Salton Sea National Wildlife Refuge (SSNWR) is located 64 km north of the Mexican border at the southern end of the Salton Sea in California's Imperial Valley. Freshwater ponds and managed habitats at the SSNWR, Calipatria, Calif. are supplied with Colorado River water that carries compounds from upstream sources. Components include municipal and industrial discharges, agricultural drainage, and sewage plant inputs. Aquatic animals in these ecosystems are continuously exposed to multiple constituents, several of which have been demonstrated to be associated with hormonal disturbances. We investigated possible endocrine impacts to fish in the Imperial Valley, Calif., by addressing the null hypothesis that aquatic species in impacted sites did not exhibit evidence of endocrine disruption as compared with those from nonimpacted sites. The results presented are intended to provide managers with science-based information and interpretations about the condition of the animals in their ecosystems for the minimization of potential adverse effects to trust fish and wildlife resources and for the maximization of available water resources.

Open-File Report↗
USGS2017

The waterfall paradox: How knickpoints disconnect hillslope and channel processes, isolating salmonid populations in ideal habitats

Waterfalls create barriers to fish migration, yet hundreds of isolated salmonid populations exist above barriers and have persisted for thousands of years in steep mountainous terrain. Ecological theory indicates that small isolated populations in disturbance-prone landscapes are at greatest risk of extirpation because immigration and recolonization are not possible. On the contrary, many above-barrier populations are currently thriving while their downstream counterparts are dwindling. This quandary led us to explore geomorphic knickpoints as a mechanism for disconnecting hillslope and channel processes by limiting channel incision and decreasing the pace of base-level lowering. Using LiDAR from the Oregon Coast Range, we found gentler channel gradients, wider valleys, lower gradient hillslopes, and less shallow landslide potential in an above-barrier catchment compared to a neighboring catchment devoid of persistent knickpoints. Based on this unique geomorphic template, above-barrier channel networks are less prone to debris flows and other episodic sediment fluxes. These above-barrier catchments also have greater resiliency to flooding, owing to wider valleys with greater floodplain connectivity. Habitat preference models further indicate that salmonid habitat is present in greater quantity and quality in these above-barrier networks. Therefore the paradox of the persistence of small isolated fish populations may be facilitated by a geomorphic mechanism that both limits their connectivity to larger fish populations yet dampens the effect of disturbance by decreasing connections between hillslope and channel processes above geomorphic knickpoints.

Geomorphology↗
USGS2011

Factors affecting winter survival of female mallards in the lower Mississippi alluvial valley

The lower Mississippi Alluvial Valley (hereafter LMAV) provides winter habitat for approximately 40% of the Mississippi Flyway's Mallard (Anas platyrhynhcos) population; information on winter survival rates of female Mallards in the LMAV is restricted to data collected prior to implementation of the North American Waterfowl Management Plan. To estimate recent survival and cause-specific mortality rates in the LMAV, 174 radio-marked female Mallards were tracked for a total of 11,912 exposure days. Survival varied by time periods defined by hunting seasons, and females with lower body condition (size adjusted body mass) at time of capture had reduced probability of survival. Female survival was less and the duration of our tracking period was greater than those in previous studies of similarly marked females in the LMAV; the product-limit survival estimate (??????SE) through the entire tracking period (136 days) was 0.54 ??0.10. Cause-specific mortality rates were 0.18 ??0.04 and 0.34 ??0.12 for hunting and other sources of mortality, respectively; the estimated mortality rate from other sources (including those from avian, mammalian, or unknown sources) was higher than mortality from non-hunting sources reported in previous studies of Mallards in the LMAV. Models that incorporate winter survival estimates as a factor in Mallard population growth rates should be adjusted for these reduced winter survival estimates.

Waterbirds↗