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USGS2013

A model for evaluating effects of climate, water availability, and water management on wetland impoundments--a case study on Bowdoin, Long Lake, and Sand Lake National Wildlife Refuges

Many wetland impoundments managed by the U.S. Fish and Wildlife Service (USFWS) National Wildlife Refuge System throughout the northern Great Plains rely on rivers as a primary water source. A large number of these impoundments currently are being stressed from changes in water supplies and quality, and these problems are forecast to worsen because of projected changes to climate and land use. For example, many managed wetlands in arid regions have become degraded owing to the long-term accumulation of salts and increased salinity associated with evapotranspiration. A primary goal of the USFWS is to provide aquatic habitats for a diversity of waterbirds; thus, wetland managers would benefit from a tool that facilitates evaluation of wetland habitat quality in response to current and anticipated impacts of altered hydrology and salt balances caused by factors such as climate change, water availability, and management actions. A spreadsheet model that simulates the overall water and salinity balance (WSB model) of managed wetland impoundments is presented. The WSB model depicts various habitat metrics, such as water depth, salinity, and surface areas (inundated, dry), which can be used to evaluate alternative management actions under various water-availability and climate scenarios. The WSB model uses widely available spreadsheet software, is relatively simple to use, relies on widely available inputs, and is readily adaptable to specific locations. The WSB model was validated using data from three National Wildlife Refuges with direct and indirect connections to water resources associated with rivers, and common data limitations are highlighted. The WSB model also was used to conduct simulations based on hypothetical climate and management scenarios to demonstrate the utility of the model for evaluating alternative management strategies and climate futures. The WSB model worked well across a range of National Wildlife Refuges and could be a valuable tool for USFWS staff when evaluating system state and management alternatives and establishing long-term goals and objectives.

Bowdoin National Wildlife Refuge;Long Lake Nationa↗

USGS1993

Monitoring and research at Walnut Creek National Wildlife Refuge

Walnut Creek National Wildlife Refuge-Prairie Learning Center (Walnut Creek or the Refuge) is one of the newest additions to the National Wildlife Refuge System, which consists of over 480 units throughout the United States operated by the U.S. Department of the Interior, Fish and Wildlife Service (the Service). Located about 20 miles east of Des Moines, Iowa, the Refuge has an approved acquisition boundary containing 8,654 acres (Figure 1). Acquisition is from willing sellers only, and to date the Service has purchased approximately 5,000 acres. The acquisition boundary encompasses about 43% of the watershed of Walnut Creek, which bisects the Refuge and drains into the Des Moines River to the southeast. Approximately 25%-30% of the Walnut Creek watershed is downstream of the Refuge. As authorized by Congress in 1990, the purposes of the Refuge are to (U.S. Fish and Wildlife Service 1992): • restore native tallgrass pairie, wetland, and woodland habitats for breeding and migratory waterfowl and resident wildlife; • serve as a major environmental education center providing opportunities for study; • provide outdoor recreation benefits to the public; and • provide assistance to local landowners to improve their lands for wildlife habitat. To implement these purposes authorized by Congress, the Refuge has established the goal of recreating as nearly as possible the natural communities that existed at the time of settlement by Euro-Americans (circa 1840). Current land use is largely agricultural, including 69% cropland, 17% grazed pasture, and 7.5% grassland (dominantly brome) enrolled in the Conservation Reserve Program). About 1,395 acres of relict native communities also exist on the Refuge, including prairie (725 acres), oak savanna and woodland (450 acres), and riparian or wetland areas (220 acres). Some of these relicts are highly restorable; others contain only a few prairie plants in a matrix of brome and will be more difficult to restore. When the process of restoration (management and enhancement of existing remnant communities) and reconstruction (reestablishment of native communities on agricultural sites) is completed, it is anticipated that the Refuge will consist of approximately 5,900 acres of prairie, 2,000 acres of oak savanna or woodland, and 750 acres of wetland and riparian communities. Ecological restoration and reconstruction at this scale in the tallgrass prairie ecosystem is unprecedented in the United States.

Report↗

USGS2011

Bats of Ouray National Wildlife Refuge

Ouray National Wildlife Refuge (NWR) is located in the northeast corner of Utah along the Green River and is part of the Upper Colorado River System and the Colorado Plateau. The Colorado Plateau is home to 19 species of bats, some of which are quite rare. Of those 19 species, a few have a more southern range and would not be expected to be found at Ouray NWR, but it is unknown what species occur at Ouray NWR or their relative abundance. The assumption is that Ouray NWR provides excellent habitat for bats, since the riparian habitat consists of a healthy population of cottonwoods with plenty of older, large trees and snags that would provide foraging and roosting habitat for bats. The more than 4,000 acres of wetland habitat, along with the associated insect population resulting from the wetland habitat, would provide ideal foraging habitat for bats. The overall objective of this project is to conduct a baseline inventory of bat species occurring on the refuge using mist nets and passive acoustic monitoring.

Open-File Report↗

USGS1984

Refuge management analyses: research needs for Muscatatuck National Wildlife Refuge

Muscatatuck National Wildlife Refuge, located in southeastern Indiana, was established by the Migratory Bird Conservation Commission in 1966. Land use planning for the Refuge formally began in 1971, and development of facilities designed in that planning effort is now nearing completion. As these facilities become operational, Refuge personnel will be manipulating water (both spatially and temporally) and other habitat components to achieve the joint Refuge goals of natural resource conservation and public use. This situation offers a unique opportunity to institute research and management studies designed to evaluate and enhance the effectiveness of the management regime in providing for the needs of migratory waterfowl and other wildlife resources.

Indiana↗

USGS2020

Environmental contamination and unusual snake mortality in an urban national wildlife refuge

The National Wildlife Refuge (NWR) System protects ~150 million acres of land and water in the United States and provides habitat for >2,000 native vertebrates species. Although legally protected, wildlife populations within these refuges can be threatened by anthropogenic activities. The lack of knowledge about such threats has the potential to undermine biodiversity conservation. We investigated patterns of wildlife mortality among three NWRs in the northern U.S. Gulf Coast. Visual surveys (958 total search-hours) were conducted for live or dead amphibians and reptiles at Big Branch, Bogue Chitto, and Bayou Sauvage NWRs. An exceptionally high incidence of snake mortality (>800% above background, P < 0.001) was observed at one site (Haul Road, Bayou Sauvage NWR). Mortality affected seven species and recurred for 29 months. Intact carcasses were subject to histopathological examination and diagnostic testing. Cause of death was undetermined (n = 9) or attributed to various pathogens (n = 5). To investigate possible underlying causes of this unusual mortality, water exposure challenges and soil toxicological analyses (n = 6 and 11 sites, respectively) were conducted on samples from Bayou Sauvage NWR, given the known potential for anthropogenic contamination in the refuge. In a controlled experiment, survival of Anaxyrus fowlerii embryos exposed to water from Recovery Road (i.e., 250m from a landfill) and Haul Road was reduced 92% and 48%, respectively, compared to four reference sites in the refuge. Sediment analyses suggested at least seven distinct sources of contaminants in Bayou Sauvage NWR. Potential sources included a landfill, illegal dumping, vehicle emissions, pesticide migration, and an active hydrocarbon pipeline leak discovered 600 m from Haul Road. Synthesis and applications: Although further research is needed to determine whether the observed mortality and contamination are related, these collective findings suggest that anthropogenic factors may threaten the ecological integrity of one of the United States largest urban wildlife refuges. More broadly, our study highlights the critical need for species inventories, baseline data, and systematic monitoring in NWRs. Such information is essential to detecting and mitigating anthropogenic threats to biodiversity conservation in protected areas.

Louisiana↗

USGS1996

Detailed study of selenium in soil, water, bottom sediment, and biota in the Sun River Irrigation Project, Freezout Lake Wildlife Management Area, and Benton Lake National Wildlife Refuge, west-central Montana, 1990-92

Selenium and other constituents are adversely affecting water quality and creating a potential hazard to wildlife in several areas of the Sun River Irrigation Project, Freezout Lake Wildlife Management Area, and Benton Lake National Wildlife Refuge in west-central Montana. Selenium derived from Cretaceous shale and Tertiary and Quaternary deposits containing shale detritus is transported in the oxic shallow ground-water systems. At Freezout Lake Wildlife Management Area, drainage from irrigated glacial deposits is the primary source of selenium; drainage from non-irrigated farmland is a significant source locally. Benton Lake generally receives more selenium from natural runoff from its non-irrigated basin than from the trans-basin diversion of irrigation return flow. Selenium has accumulated in aquatic plants and invertebrates, fish, and water birds, particularly in wetlands that receive the largest selenium loads. Although selenium residues in biological tissue from some wetland units exceeded biological risk levels, water-bird reproduction generally has not been impaired. The highest selenium residues in biota commonly occurred in samples from Priest Butte Lakes, which also had the highest selenium concentration in wetland water. Selenium concentrations in all invertebrate samples from Priest Butte Lakes and the south end of Freezeout Lake exceeded the critical dietary threshold for water birds. Selenium delivered to wetlands accumulates in bottom sediment, predominantly in near-shore areas. Potential impacts to water quality, and presumably biota, may be greatest near the mouths of inflows. Most selenium delivered to wetlands will continue to accumulate in bottom sediment and biota.

Water-Resources Investigations Report↗

USGS2013

Identification of metrics to monitor salt marsh integrity on National Wildlife Refuges in relation to conservation and management objectives

Executive Summary Most salt marshes in the US have been degraded by human activities, and threats from physical alterations, surrounding land-use, species invasions, and global climate change persist. Salt marshes are unique and highly productive ecosystems with high intrinsic value to wildlife, and many National Wildlife Refuges (NWRs) have been established in coastal areas to protect large tracts of salt marsh and wetland-dependent species. Various management practices are employed routinely on coastal NWRs to restore and enhance marsh integrity and ensure ecosystem sustainability. Prioritizing NWR salt marshes for application of management actions and choosing among multiple management options requires scientifically-based methods for assessing marsh condition. Monitoring is integral to structured decision-making (SDM), a formal process for decomposing a decision into its essential elements. Within a natural resource context, SDM involves identifying management objectives, alternative management actions, and expected management outcomes. The core of SDM is a set of criteria for measuring system performance and evaluating management responses. Therefore, use of SDM to frame natural resource decisions leads to logical selection of monitoring attributes that are linked explicitly to management needs. We used SDM to guide selection of variables for monitoring the ecological integrity of salt marshes within the National Wildlife Refuge System (NWRS). Our objectives were to identify indicators of salt marsh integrity that are effective across large geographic regions, responsive to a wide range of threats, and feasible to implement within funding and staffing constraints of the NWRS. In April, 2008, we engaged interdisciplinary experts in a week-long rapid prototyping SDM workshop to define the essential elements of salt marsh management decisions on refuges throughout the northeastern, southwestern, and northwestern US, corresponding to respective Regions 5, 2, and 1 of the US Fish and Wildlife Service (FWS). Through this process we identified measurable attributes for monitoring salt marsh ecosystems that are integrated into conservation practice and target management objectives. The following salt marsh attributes were identified through the SDM process either for describing state condition to determine management needs or for evaluating the achievement of management objectives: historical condition and geomorphic setting; ditch density; surrounding land use; ratio of open water area to vegetation area; rate of pesticide application; environmental contaminant concentration; change in marsh surface elevation relative to sea level rise; tidal range and groundwater level; surface topography; salinity; and species composition and abundance of vegetation, invasive species, invertebrates, nekton, and breeding and wintering birds. The identified attributes were too broadly defined to serve as operational monitoring variables. Therefore, we tested specific metrics for quantifying most of these attributes in summers of 2008 and 2009. The first four attributes in the above list can be characterized by office-based analysis of existing GIS data layers. The remaining attributes require field-based methods for assessment. We were forced to exclude a small number of attributes from field tests due to inconsistent data (pesticide application rate, environmental contaminant concentrations) or requirements that exceeded the scope of this project (change in marsh surface elevation; surface topography; benthic invertebrates; wintering birds). We evaluated potential metrics for evaluating all remaining field attributes. In partnership with NWRS biologists, we tested rapid versus intensive metrics for monitoring field attributes (tidal range and groundwater level; marsh surface elevation; salinity; and species composition and abundance of vegetation, invasive species, nekton, and breeding birds) at coastal refuges throughout FWS Region 5. Seven refuges participated in metric testing in 2008: Rachel Carson (ME), Parker River (MA), Wertheim (NY), E. B. Forsythe (NJ), Bombay Hook (DE), Prime Hook (DE), and Eastern Shore of Virginia Complex (VA). These seven and two additional refuges participated in metric testing in 2009: Rhode Island Complex (RI) and Stewart B. McKinney (CT). We based all field metrics on existing protocols for salt marsh assessment. Sampling locations were determined randomly within delineated marsh study units (MSUs) at each refuge. Detailed field methods are provided in appendices to this report. Measurements for individual metrics were averaged across samples within MSUs during each year of sampling. Each year, correlation or regression analysis was conducted on average measurements across MSUs within each attribute set to identify redundant metrics. Statistical redundancy between a pair of metrics within an attribute set (i.e., correlation or regression slopes with p-values < 0.05) was considered justification for eliminating one of the pair from the regional set of monitoring metrics. Decisions regarding metric elimination versus retention were based on feasibility of monitoring, considering such factors as sampling time, resources required, and potential for regional standardization in implementation. The result of these tests is a reduced suite of monitoring metrics that targets NWRS management decisions and is practicable for implementing on a regional scale. Based on these tests, we recommend the following list of metrics for monitoring integrity of NWRS salt marshes (marsh attribute category is in parentheses): (historical condition and geomorphic setting) position of marsh in the landscape, marsh shape, degree of fill and/or fragmentation, degree of tidal flushing, amount of aquatic edge; (ditch density) ranking of ditch density from none to severe; (surrounding land use) relative proportion of agricultural land in a 150-m buffer around the marsh, relative proportion of natural land in a 150-m buffer around the marsh, relative proportion of natural land in a 1-km buffer around the marsh; (ratio of open water area to vegetation area) ratio of open water to emergent herbaceous wetlands within the marsh; (marsh surface elevation) elevation referenced to NAVD88 in a representative area of the marsh; (tidal range and groundwater level) percent of time the marsh surface is flooded during deployment of a continuous water-level monitor at a representative marsh location, mean depth of surface flooding as measured by a continuous water-level monitor at a representative location; (salinity) salinity measured in surface water; (vegetation community) vegetation species richness using the point-intercept method in 100-m diameter survey plots, percent cover of various marsh community types within 100-m diameter survey plots; (invasive species abundance) percent cover of invasive plant species measured using the point-intercept method in 100-m diameter survey plots; (nekton community) nekton density, nekton species richness, length of Fundulus heteroclitus ; (breeding bird community) abundance of Willets counted per point during standard call-broadcast surveys, summed abundance of tidal marsh obligate species (Clapper Rail, Willet, Saltmarsh Sparrow, Seaside Sparrow) counted per point during standard call-broadcast surveys. Metrics describing the historical condition, geomorphic setting, and broad landscape features can be assessed using existing GIS databases. Our results support use of rapid methods to assess the majority of field metrics; only those used to describe the nekton community must be measured using intensive methods (throw traps or ditch nets, dependant on habitat configuration). Implementation of these metrics for quantitative assessment of NWRS salt marsh integrity in FWS Region 5 requires developing sampling designs for each refuge. Additionally, it is important to determine how the monitoring information will be used within a management context. SDM should be used to complete the analysis of salt marsh management decisions. The next steps would involve 1) prioritizing and weighting the management objectives; 2) predicting responses to individual management actions in terms of objectives and metrics; 3) using multiattribute utility theory to convert all measurable attributes to a common utility scale; 4) determining the total management benefit of each action by summing utilities across objectives; and 5) maximizing the total management benefits within cost constraints for each refuge. This process would allow the optimum management decisions for NWRS salt marshes to be selected and implemented based directly on monitoring data and current understanding of marsh responses to management actions. Monitoring the outcome of management actions would then allow new monitoring data to be incorporated into subsequent decisions.

Connecticut, Delaware, Maine, Massachusetts, New J↗

USGS2012

National wildlife refuge visitor survey 2010/2011: Individual refuge results

The National Wildlife Refuge System (Refuge System), established in 1903 and managed by the U.S. Fish and Wildlife Service (Service), is the leading network of protected lands and waters in the world dedicated to the conservation of fish, wildlife and their habitats. There are 556 national wildlife refuges and 38 wetland management districts nationwide, encompassing more than 150 million acres. The Refuge System attracts more than 45 million visitors annually, including 25 million people per year to observe and photograph wildlife, over 9 million to hunt and fish, and more than 10 million to participate in educational and interpretation programs. Understanding visitors and characterizing their experiences on national wildlife refuges are critical elements of managing these lands and meeting the goals of the Refuge System. The Service collaborated with the U.S. Geological Survey to conduct a national survey of visitors regarding their experiences on national wildlife refuges. The survey was conducted to better understand visitor needs and experiences and to design programs and facilities that respond to those needs. The survey results will inform Service performance planning, budget, and communications goals. Results will also inform Comprehensive Conservation Plan (CCPs), Visitor Services, and Transportation Planning processes. This data series consists of 53 separate data files. Each file describes the results of the survey for an individual refuge and contains the following information: * Introduction: An overview of the Refuge System and the goals of the national surveying effort. * Methods: The procedures for the national surveying effort, including selecting refuges, developing the survey instrument, contacting visitors, and guidance for interpreting the results. * Refuge Description: A brief description of the refuge location, acreage, purpose, recreational activities, and visitation statistics, including a map (where available) and refuge website link. * Sampling at This Refuge: The sampling periods, locations, and response rate for the refuge. * Selected Survey Results: Key findings for the refuge, including: - Visitor and Trip Characteristics - Visitor Spending in the Local Communities - Visitors Opinions about This Refuge - Visitor Opinions about National Wildlife Refuge System Topics * Conclusion * References * Survey Frequencies (Appendix A): The survey instrument with the frequency results for this refuge. * Visitor Comments (Appendix B): The verbatim responses to the open-ended survey questions for this refuge. Combined results for the 53 participating refuges are available at http://pubs.usgs.gov/ds/685/ as part of USGS Data Series 685.

Data Series↗

USGS2015

Draft comprehensive conservation plan and environmental impact statement-Rocky Mountain Arsenal National Wildlife Refuge

The Rocky Mountain Arsenal National Wildlife Refuge Complex, consisting of some of the newer properties in the National Wildlife Refuge System, is a work in progress. Offering unique assets to surrounding communities, these lands promise to become some of the premier urban wildlife refuges in the country. At the heart of the refuge complex is the Rocky Mountain Arsenal National Wildlife Refuge: 16,000 acres of shortgrass and mixed-grass prairie that is home to bison, bald eagles, migratory songbirds, prairie dogs, and much more—all within the Denver Metropolitan area. This comprehensive conservation plan will be the first in the country designed to begin implementing the Refuge System’s new Urban Refuge Initiative. To accomplish this, we analyzed a wide range of options on how best to support up to one million visitors per year without compromising our principal purposes to protect and preserve fish and wildlife and their habitats. We are fortunate to have inherited a great deal of infrastructure from the U.S. Army, but we are also constrained by the current condition and layout of these facilities. Some of this infrastructure may be acting as barriers to the public—a condition inconsistent with the purposes of the refuge. Accordingly, we have developed a goal to increase and improve suitable access to the refuge, develop sustainable transportation options, and provide more connections among the units of the refuge complex. This increased access will enable people from all walks of life to visit the refuge. The vision we have developed for the refuge complex calls for the restoration of the refuge’s historical habitats, and the reconnection of people with the natural lands of the refuge and of the region at large using a network consisting of multimodal trails, a far-reaching light-rail system, and the Denver International Airport. This refuge is well positioned to leverage and catalyze early investments to create world-class wildlife habitat and a conservation education facility in the heart of a rapidly growing urban metropolis. So positioned, the refuge represents the ideal intersection of nature and education to transmit the message of conservation, outdoor recreation, and stewardship to future generations. Toward this end, collaboration is essential to the refuge’s future success. We will continue to foster and improve our strong public and private partnerships in the surrounding communities. These partnerships will enable us to act quickly and effectively as we invest in education and outreach efforts to fulfill our potential as a conservation catalyst in neighboring communities, the larger Intermountain West, and the world.

Report↗

USGS2015

Draft comprehensive conservation plan and environmental impact statement - Rocky Mountain Arsenal National Wildlife Refuge

Colorado↗

USGS2013

User’s manual to update the National Wildlife Refuge System Water Quality Information System (WQIS)

National Wildlife Refuges may have impaired water quality resulting from historic and current land uses, upstream sources, and aerial pollutant deposition. National Wildlife Refuge staff have limited time available to identify and evaluate potential water quality issues. As a result, water quality–related issues may not be resolved until a problem has already arisen. The National Wildlife Refuge System Water Quality Information System (WQIS) is a relational database developed for use by U.S. Fish and Wildlife Service staff to identify existing water quality issues on refuges in the United States. The WQIS database relies on a geospatial overlay analysis of data layers for ownership, streams and water quality. The WQIS provides summary statistics of 303(d) impaired waters and total maximum daily loads for the National Wildlife Refuge System at the national, regional, and refuge level. The WQIS allows U.S. Fish and Wildlife Service staff to be proactive in addressing water quality issues by identifying and understanding the current extent and nature of 303(d) impaired waters and subsequent total maximum daily loads. Water quality data are updated bi-annually, making it necessary to refresh the WQIS to maintain up-to-date information. This manual outlines the steps necessary to update the data and reports in the WQIS.

Techniques and Methods↗

USGS2006

Final integrated trip report: site visits to Area 50, Andersen Air Force Base, Guam National Wildlife Refuge, War in the Pacific National Historical Park, Guam, Rota and Saipan, CNMI, 2004-2005

Limestone forests are the most diverse natural plant communities of Guam. Like other natural vegetation types, these forests have a long history of anthropogenic disturbances, being altered and shaped by humans for more than 4,000 years. Although this occupation represents a relatively long human influence in comparison to other Pacific islands, animals associated with humans, such as commensal rodents, arrived in these islands beginning only 1,000 years ago, and larger mammals, such as pigs (Sus scrofa), may not have arrived until European contact. Limestone forests, which also occur on several other Mariana Islands, developed in the presence of frequent tropical storms and are therefore well adapted to this type of natural disturbance regime. However, recent human activities including large scale clearing and conversion combined with the presence of high levels of alien herbivores and seed predators, and the loss of ecological services provided by the former native avifauna may be causing the decline of Guam's forests. Limestone forests on northern Guam, much like those of other Mariana Islands, were heavily cleared for the construction of military installations during World War II. The accidental introduction of the Brown Tree Snake (Boiga irregularis; BTS) around this same period subsequently accelerated the disappearance of Guam's native avifauna and other endemic terrestrial vertebrates, and with them, seed dispersal, pollination, and the predatory regulation of herbivorous insects. Guam and the Mariana Islands contained a high proportion (32 pecent) of endemic bird species, with 4 forms endemic to Guam alone: the now extinct Guam Flycatcher (Myiagra freycineti), and Guam Bridled White-eye (Zosterops conspicillatpicillata), one of three island endemic subspecies from the Marianas; Guam rail (Rallus owstonii); and Guam Kingfisher (Todiramphus cinnamominus cinnamominus), an island endemic subspecies of the regionally endemic Micronesian Kingfisher. Guam once supported the Mariana Gallinule (Gallinula chloropus guami), the Mariana Mallard (Anas platyrhynchos oustaleti), Mariana Fruit-Dove (Ptilinopus roseicapilla), White-throated Ground Dove (Gallicolumba xanthonura xanthonura), Mariana Crow (Corvus kubaryi), and the Nightingale Reed-warbler (Acrocephalus luscinia), all endemic to the Mariana Islands. Other regionally endemic endangered species include the Micronesian Megapode (Megapodius laperouse), and the Mariana Swiftlet (Aerodramus bartschi), now reduced to a small population on Guam. Likewise, the flora of Guam is unique, with 21percent of its native vascular plants endemic to the Mariana Islands. In limestone forests of Northern Guam, a number of tall forest tree species such as joga, Elaeocarpus joga (Elaeocarpaceae); pengua or Macaranga thompsonii (Euphorbiaceae); ifit or Intsia bijuga (Fabaceae); seeded breadfruit or Artocarpus marianensis (Moraceae); and umumu or Pisonia grandis (Nyctaginaceae) may be in decline as a result of herbivory by mammals. All show reduced regeneration and age distributions highly skewed towards older individuals. These species provided important habitat for some of Guam's endangered forest birds that remain in captivity such as the Mariana Crow, Guam Kingfisher, and Guam Rail. The recent high frequency of intense tropical storms and herbivory caused by large populations of feral pigs and Philippine sambar deer (Cervus mariannus), as well as invasive alien vines that may suppress tree regeneration, could be permanently altering the structure of regenerating forests and composition of important canopy species on secondary limestone substrates that were cleared and compacted during airfield construction from 1944 through the 1970s. Guam National Wildlife Refuge (GNWR) was established at Ritidian Point, after it was determined to be excess property by the U.S. Navy. Most of the refuge, about 9,087 hectares, is an 'overlay refuge' on lands administered by the U.S. Air Force and U.S. Navy. Although the military mission comes first on these lands, the U.S. Fish and Wildlife Service assists in protecting native species and habitats. The recovery of limestone forest on Guam for forest bird habitat may require intensive management, including reduction of feral herbivores, propagation, out-planting, weed control, and periodic suppression of herbivorous insects. Research to support these techniques may be best accomplished in small areas where potential limiting factors can easily be experimentally manipulated. Area 50, a 24 ha enclosure, contains a relictual patch of relatively undisturbed limestone forest surrounded by tarmac allowing easy access and management opportunities to control alien mammals and snakes. These species have been periodically managed in the past, but recent typhoons have damaged snake-proofing on the enclosure fence. A new concrete barrier is planned to provide more permanent control opportunities within this enclosed area or another similar area, thereby allowing experimental research for various management regimes. Eradication and control of alien vertebrate and plant pests will provide habitat where native communities can be restored in a small, intensively managed area. The stated aim of this project is to "affect ecosystem restoration through the removal and exclusion of introduced species and the reestablishment and propagation of native species, with focus on the reintroduction of native forest bird species." This will be achieved by constructing a multispecies barrier surrounding the area, coordinated eradication of selected alien species within the area, and possible reintroduction of Mariana Crow, Guam Kingfisher, and Guam Rail. This barrier also allows experimental research questions to be addressed within the small enclosure around Area 50 that may be applied to manage and restore the larger areas of limestone forest on northern Guam and also similar forests on other islands of the Marianas.

Open-File Report↗

USGS2013

National wildlife refuge visitor survey 2012--Individual refuge results

The National Wildlife Refuge System (Refuge System), established in 1903 and managed by the U.S. Fish and Wildlife Service (Service), is the leading network of protected lands and waters in the world dedicated to the conservation of fish, wildlife and their habitats. There are 560 national wildlife refuges and 38 wetland management districts nationwide, encompassing more than 150 million acres. The Refuge System attracts nearly 45 million visitors annually, including 34.8 million people who observe and photograph wildlife, 9.6 million who hunt and fish, and nearly 675,000 teachers and students who use refuges as outdoor classrooms. Understanding visitor perceptions of refuges and characterizing their experiences on refuges are critical elements of managing these lands and meeting the goals of the Refuge System. The Service collaborated with the U.S. Geological Survey to conduct a national survey of visitors regarding their experiences on national wildlife refuges. The purpose of the survey was to better understand visitor experiences and trip characteristics, to gauge visitors’ levels of satisfaction with existing recreational opportunities, and to garner feedback to inform the design of programs and facilities. The survey results will inform performance, planning, budget, and communications goals. Results will also inform Comprehensive Conservation Plans (CCPs), visitor services, and transportation planning processes. This Data Series consists of 25 separate data files. Each file describes the results of the survey for an individual refuge and contains the following information: • Introduction: An overview of the Refuge System and the goals of the national surveying effort. • Methods: The procedures for the national surveying effort, including selecting refuges, developing the survey instrument, contacting visitors, and guidance for interpreting the results.• Refuge Description: A brief description of the refuge location, acreage, purpose, recreational activities, and visitation statistics, including a map (where available) and refuge website link. • Sampling at This Refuge: The sampling periods, locations, and response rate for the refuge. • Selected Survey Results: Key findings for the refuge, including: o Visitor and trip characteristics o Visitor spending in the local communities o Visitors opinions about the refuge o Visitor opinions about National Wildlife Refuge System topics • Conclusion • References Cited • Survey Frequencies (Appendix A): The survey instrument with frequency results for the refuge. • Visitor Comments (Appendix B): The verbatim responses to the open-ended survey questions for the refuge.Individual-refuge results for the 53 participating refuges in the 2010-2011 national effort are available at http://pubs.usgs.gov/ds/643/ as part of USGS Data Series 643. Combined results for the 53 participating refuges in the 2010-2011 national effort are available at http://pubs.usgs.gov/ds/685/ as part of USGS Data Series 685.

Data Series↗

USGS2013

Information to support to monitoring and habitat restoration on Ash Meadows National Wildlife Refuge

The Ash Meadows National Wildlife Refuge staff focuses on improving habitat for the highest incidence of endemic species for an area of its size in the continental United States. Attempts are being made to restore habitat to some semblance of its pre-anthropogenic undisturbed condition, and to provide habitat conditions to which native plant and animal species have evolved. Unfortunately, restoring the Ash Meadows’ Oases to its pre-anthropogenic undisturbed condition is almost impossible. First, there are constraints on water manipulation because there are private holdings within the refuge boundary; second, there has been at least one species extinction—the Ash Meadows pool fish ( Empetrichthys merriami ). It is also quite possible that thermal endemic invertebrate species were lost before ever being described. Perhaps the primary obstacle to restoring Ash Meadows to its pre-anthropogenic undisturbed conditions is the presence of invasive species. However, invasive species, such as red swamp crayfish ( Procambarus clarki ) and western mosquitofish ( Gambusia affinis ), are a primary driving force in restoring Ash Meadows’ spring systems, because under certain habitat conditions they can all but replace native species. Returning Ash Meadows’ physical landscape to some semblance of its pre-anthropogenic undisturbed condition through natural processes may take decades. Meanwhile, the natural dissolution of concrete and earthen irrigation channels threatens to allow cattail marshes to flourish instead of spring-brooks immediately downstream of spring discharge. This successional stage favors non-native crayfish and mosquitofish over the native Amargosa pupfish ( Cyprinodon nevadensis ). Thus, restoration is needed to control non-natives and to promote native species, and without such intervention the probability of native fish reduction or loss, is anticipated. The four studies in this report are intended to provide information for restoring native fish habitat and for monitoring native fish populations in relation to restoration efforts on the Ash Meadows National Wildlife Refuge. There are no precise records on conditions of each of the spring systems prior to anthropogenic alteration; however, fostering conditions that favor native over non-natives will be key to habitat restoration. Information regarding native species carbon source is needed to create habitat that favors native species, thus habitat restoration fostering food stuff consumed by native species should be considered in restoration efforts. In compiling data for the first part of this report, we tracked carbon source for native and non-native species at four stations along the Jackrabbit Spring system. Thus, we were able to contrast carbon source in warm- and cool-water habitats. Habitat in Jackrabbit Spring was improved for native fishes in 2007. The second paper in this report focuses on native fish populations in Jackrabbit Spring system pre- and post-restoration. Much of the Ash Meadows Oases is marsh habitat where non-native red swamp crayfish and western mosquitofish are often abundant, to the detriment of non-natives. Because marsh habitat is broadly represented in the Ash Meadows landscape, establishing marsh habitat most conducive to the native fishes is important to the restoration effort, and the third paper addresses marsh habitat type with the relative abundance of fishes and crayfish. There are previous years of monitoring Ash Meadows’ native fish populations, but not all monitoring occurred at the same time of year. Desert-fish populations sometimes undergo seasonal fluctuation, so it might not be valid to compare population trends using difference seasons. For report four, we tracked a closed population of Amargosa pupfish ( Cyprinodon nevadensis ) year round to track seasonal trends. Knowledge of seasonal trends is important in tracking changes of populations pre- and post-restoration.

Nevada↗

USGS2013

Mercury in wetlands at the Glacial Ridge National Wildlife Refuge, northwestern Minnesota, 2007-9

The Glacial Ridge National Wildlife Refuge was established in 2004 on land in northwestern Minnesota that had previously undergone extensive wetland and prairie restorations. About 7,000 acres of drained wetlands were restored to their original hydrologic function and aquatic ecosystem. During 2007–9, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service and the Red Lake Watershed District, analyzed mercury concentrations in wetland water and sediment to evaluate the effect of wetland restoration on mercury methylation. The wetland waters sampled generally were of the calcium/magnesium bicarbonate type. Nitrogen in water was mostly in the form of dissolved-organic nitrogen, with very low dissolved-nitrate and dissolved-ammonia concentrations. About 71 percent of all phosphorus in water was dissolved, with one-half of that in the form of orthophosphorus. Wetland water had total-mercury and methylmercury concentrations ranging from 1.5 to 20 nanograms per liter (ng/L) and 0.2 to 16 ng/L, respectively. Median concentrations were 7.1 and 2.9 ng/L, respectively. About one-half of the mercury in wetland water samples was in the form of methylmercury, but this form ranged from 7 to 81 percent of each sample. Compared to concentrations in stream sediment samples collected throughout the United States, Glacial Ridge National Wildlife Refuge wetland sediment samples contained typical total-mercury concentrations, but methylmercury concentrations were nearly twice as high. The maximum concentration measured in Glacial Ridge National Wildlife Refuge wetland water approached the highest published water methylmercury concentration in uncontaminated waters of which we are aware. However, the upper quartile of water methylmercury concentrations is similar to concentrations reported for some impoundments and wetlands in northwestern Minnesota and North Dakota. Methylmercury concentrations in sampled wetlands were much higher than those from typical lakes or flowing streams throughout the United States. The high concentrations of methylmercury measured in sampled wetlands indicate the potential for substantial methylmercury concentrations in aquatic biota and wildlife that consume those biota. These wetlands also are a methylmercury source for downstream lakes and rivers. The high concentrations of methylmercury in water, its bioaccumulation potential, and its known toxicity in aquatic birds and food webs highlight a need to assess methylmercury in the biota within these ecosystems. Better understanding of factors that control methylmercury production concentrations within aquatic food webs in ecosystems of the Glacial Ridge National Wildlife Refuge would enable resource managers to better understand and manage risk to wildlife.

Minnesota↗

USGS2020

Detectability and abundance of snowy plovers at Salt Plains National Wildlife Refuge, Oklahoma

In the past two decades, Salt Plains National Wildlife Refuge has been increasingly recognized as important habitat for both breeding and migratory shorebirds. North American snowy plovers Charadrius nivosus in particular rely on the nearly 5,000-ha salt flat at Salt Plains National Wildlife Refuge, which thousands use as breeding and stopover habitat. Elsewhere on the Southern Great Plains, decadal declines up to 75% within snowy plover subpopulations have been documented and attributed to vegetation encroachment, increased rates of nest predation, and decreased availability of fresh surface water. Despite many attempts to estimate this species' abundance across the continent, to date, no known attempt at distance sampling of snowy plovers has occurred. To address this paucity of data, we assessed feasibility of distance sampling methods to accurately estimate snowy plover abundance and detectability. Distance sampling surveys (2017–2018) indicated high detection probability ( P = 0.80) and the population abundance estimate across the salt flat extrapolated to 3,307 individuals. The distance-sampling population abundance estimate is lower than population abundance estimates determined by two previous studies within the past decade but far greater than 2,105 estimated for a study in 2006. Overall, distance sampling snowy plovers at Salt Plains National Wildlife Refuge proved to be an effective addition to pre-established survey protocols but further investigation is needed to compare accuracy and precision of methods used in this study, annual surveys conducted by Salt Plains National Wildlife Refuge, and other potential snowy plover surveys.

Oklahoma↗

USGS2005

Potential impact of Dare County landfills on Alligator River National Wildlife Refuge

Runoff of leachate from East Lake and Dare County Construction and Demolition Debris landfills has the potential to impact wildlife resources at Alligator River National Wildlife Refuge, Dare and Hyde Counties, North Carolina. Sediment quality of samples collected in August 2000 at 14 locations down-gradient from the landfills was assessed by measuring metal and organic contaminants in the sediments, chronic toxicity of solid-phase sediment (28-d static-renewal exposures; survival and growth as test endpoints) and acute toxicity of sediment porewater (96-h static exposures) to Hyalella azteca (Crustacea: Amphipoda). In addition, contaminant bioaccumulation from 4 sediments was determined using 28-d exposures of Lumbriculus variegatus (freshwater oligochaete). Although survival was not impaired, length of H. azteca was significantly reduced in sediments from 5 locations. Pore water from 4 locations was acutely toxic to H. azteca. Metals and a few polycyclic aromatic hydrocarbons (PAHs) were bioaccumulated by L variegatus from the sediments. Several metals and PAHs exceeded sediment quality guidelines, and metals in porewater from several sites exceeded water quality criteria for the protection of aquatic wildlife. Runoff of leachate from the landfills has reduced sediment quality and has the potential to adversely affect wildlife resources at Alligator River National Wildlife Refuge.

North Carolina↗

USGS1989

Contaminant residues in fish from Tensas River National Wildlife Refuge

Tensas River National Wildlife Refuge, Madison Parish, Louisiana, consists of bottomland hardwood swamps interspersed with small lakes and bayous supporting a diverse assemblage of waterfowl, fish, and assorted species of game and nongame wildlife. Fish collected in the refuge in 1984–85 from areas receiving direct inflow from agricultural runoff contained from 5 to 10 μg/g total DDT (primarily DDE) and toxaphene (measured on a whole-body, wet-weight basis). These concentrations in fish, which were still high enough to pose a threat to fish-eating birds and wildlife, demonstrated that residues from past use of DDT and toxaphene in the area were still available for transport and uptake. In future water projects, the incorporation of structures to prevent contaminated runoff from entering the refuge should reduce waterborne contamination to the refuge.

Lake and Reservoir Management↗