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USGS2017

Vegetation map for the Hakalau Forest Unit of the Big Island National Wildlife Refuge Complex on the island of Hawai‘i

This vegetation map was produced to serve as an updated habitat base for management of natural resources of the Hakalau Forest Unit (HFU) of the Big Island National Wildlife Refuge Complex (Refuge) on the island of Hawai‘i. The map is based on a vegetation map originally produced as part of the U.S. Fish and Wildlife Service’s Hawai‘i Forest Bird Survey to depict the distribution, structure, and composition of plant communities on the island of Hawai‘i as they existed in 1977. The current map has been updated to represent current conditions of plant communities in the HFU, based on WorldView 2 imagery taken in 2012 and very-high-resolution imagery collected by Pictometry International from 2010 to 2014. Thirty-one detailed plant communities are identified on this map, and fourteen of these units are found within the boundaries of HFU. Additionally, the mapped units can be displayed as five tree canopy cover units, three moisture zones units, eight dominant tree species units, and four habitat status units by choosing the various fields to group the units from the map attribute table. This updated map will provide a foundation for the refinement and tracking of management actions on the Refuge for the near future, particularly as the habitats in this area are subject to projected climate change.

Hawai'i↗

USGS2000

Potential oil and gas resources of the Arctic National Wildlife Refuge in Alaska: 1002 area

A geologist with extensive experience in the study of northern Alaska's petroleum resources provides an overview of the first comprehensive reassessment of the petroleum potential of section 1002 of the Arctic National Wildlife Refuge since the original study of 1987. The paper surveys the region's geology, and provides a description of the methods employed and assessment results. The current resource is compared with that estimated in the original study, and is considerably larger, given the availability of new geologic and geophysical data, improved seismic processing and interpretation capabilities, and changes in the economics of North Slope oil development.

Alaska↗

USGS1977

Experimental woodcock management at the Moosehorn National Wildlife Refuge

The purpose of this study is to develop woodcock(Philohela minor) management techniques that can be easily used by the small landowner or incorporated with other land management operations such as commercial timber harvesting. The Moosehorn National Wildlife Refuge contains areas which are characteristic of the abandoned farms now being purchased for recreation or retirement as well as areas suitable for commercial forest management. Woodcock management, beginning in 1973, has centered on rejuvenation of diurnal habitat and creation of summer fields and singing grounds. Strips (10 mwide, 25 to 125 mlong and separated by 40 m) were clear~cut in two alder (Alnus sp.) stands resulting in increased diurnal use in at least one cover, increased singing male use and good alder regeneration. Small clear-cuts (30 X30 m) in a large contiguous woodland (1200 ha) with a history of few singing males resulted in an increased number of singing males despite an overall decrease in the number of singing males throughout the refuge. Management strategies and recommendations also are given.

Book chapter↗

USGS2018

Evaluation of vegetation-fire dynamics in the Okefenokee National Wildlife Refuge, Georgia, USA, with a Bayesian belief network

Vegetation response to wildfire has been studied extensively in upland ecosystems, but fire effects on temperate wetlands are less understood. We evaluated vegetation response to extensive wildfire in wetlands of Okefenokee National Wildlife Refuge (ONWR), USA, with a spatially explicit Bayesian belief network model informed with data recorded during 1990–2012. We assessed model accuracy and effects of fire frequency on vegetation composition with predictive scenarios of fire absence or a fire return interval (FRI) every 5 or 10 years during 2012–2032. In fire absence, shrubs increased 100%, primarily in the northern half of the Refuge, while the herbaceous class that was widespread in 2012 was eliminated. Areas dominated by forest during the past ~65 years were maintained with the 5- and 10-year FRI. Herbaceous-dominated areas maintained with the 5-year FRI decreased (90%) with the 10-year FRI. Shrub coverage increased with fire (17%, 5-year FRI; 20%, 10-year FRI), while scrub/shrub decreased (12%; 5-year FRI) or increased (6%; 10-year FRI). A 5-year FRI during conditions promoting severe fire may maintain the distribution of herbaceous and forested areas that followed an extensive drought and fires in 2011, and may limit scrub/shrub expansion that previously occurred with longer FRIs in the ONWR.

Georgia↗

USGS2000

Patterns of change in tree islands in Arthur R. Marshall Loxahatchee National Wildlife Refuge from 1950 to 1991

Size, shape, orientation, and distribution of tree islands in a remnant of northern Everglades wetland were examined from 1950 and 1991 aerial photography. The objectives were to quantify the patterns of tree islands in Loxahatchee National Wildlife Refuge, to determine if the patterns of tree islands had changed between the two dates, and to relate the tree island patterns to modeled pre- and post-drainage hydrologic patterns. There was considerable variation in the patterns of tree islands spatially and temporally. Changes in the size and shape of tree islands from 1950 to 1991 are consistent with changes in the modeled pre- and post-drainage hydrologic patterns. Photo plots along the edges of the refuge, where hydroperiods are longer and depths deeper than they were historically, show a decrease in tree island size and in overall area of tree islands in the plots. Photo plots in the interior, where hydroperiods are shorter than they were pre-drainage, show an increase in tree island area. Overall, there is a tendency for more tree islands to be irregularly shaped in the 1991 photo plots than in the 1950 plots, a reflection of the loss of water flow, reduction of pulse magnitude, and the ponding of water along the perimeter dikes. This study illustrates the importance of considering long-term changes in hydroperiod, depths, and water flows in the restoration of this area.

Florida↗

USGS2012

Summary of oceanographic and water-quality measurements near the Blackwater National Wildlife Refuge, Maryland, 2011

Suspended-sediment transport is a critical element governing the geomorphology of tidal marshes. Marshes rely on both organic material and inorganic sediment deposition to maintain their elevation relative to sea level. In wetlands near the Blackwater National Wildlife Refuge, Maryland, portions of the salt marsh have been subsiding relative to sea level since the early 20th century. Other portions of the marsh have been successful at maintaining elevation. The U.S. Geological Survey performed observational deployments to measure suspended-sediment concentration in the tidal channels in order to understand the magnitude of suspended-sediment concentrations, the sediment-transport mechanisms, and differences between two marsh areas, one that subsided and one that maintained elevation. We deployed optical turbidity sensors and acoustic velocity meters at multiple sites over two periods in 2011. This report presents the time-series of oceanographic data collected during those field studies, including velocity, depth, turbidity, salinity, water temperature, and pH.

Maryl↗

USGS2014

Change in agricultural land use constrains adaptation of national wildlife refuges to climate change

Land-use change around protected areas limits their ability to conserve biodiversity by altering ecological processes such as natural hydrologic and disturbance regimes, facilitating species invasions, and interfering with dispersal of organisms. This paper informs USA National Wildlife Refuge System conservation planning by predicting future land-use change on lands within 25 km distance of 461 refuges in the USA using an econometric model. The model contained two differing policy scenarios, namely a ‘business-as-usual’ scenario and a ‘pro-agriculture’ scenario. Regardless of scenario, by 2051, forest cover and urban land use were predicted to increase around refuges, while the extent of range and pasture was predicted to decrease; cropland use decreased under the business-as-usual scenario, but increased under the pro-agriculture scenario. Increasing agricultural land value under the pro-agriculture scenario slowed an expected increase in forest around refuges, and doubled the rate of range and pasture loss. Intensity of land-use change on lands surrounding refuges differed by regions. Regional differences among scenarios revealed that an understanding of regional and local land-use dynamics and management options was an essential requirement to effectively manage these conserved lands. Such knowledge is particularly important given the predicted need to adapt to a changing global climate.

Environmental Conservation↗

USGS2022

Eelgrass (Zostera marina) and seaweed abundance along the coast of Nunivak Island, Yukon Delta National Wildlife Refuge, Alaska, 2010

Eelgrass (<em>Zostera marina</em>) is a highly productive seagrass that plays an essential role in the health of the estuarine and coastal ecosystems; however, information about its abundance and distribution is insufficient in the Bering Sea along the Yukon Delta National Wildlife Refuge. We inventoried the spatial extent and abundance of eelgrass and seaweed in Duchikthluk and Shoal bays on Nunivak Island in July 2010. Using Landsat Thematic Mapper imagery, we estimated the spatial extent of eelgrass to be 1,232 hectares in Duchikthluk Bay and 40 hectares in Shoal Bay. The overall accuracy of the assessments was high (86–87 percent) based on ground truthing using field reference points. We used point-sampling methodology to assess eelgrass abundance relative to the presence of associated seaweeds and selected macro-invertebrates within each of bays. Eelgrass was found at water depths ranging from 0.1 to 2.9 meters across both bays, but the greatest density (>75 percent cover) occurred primarily in moderate to deep water (0.7–1.4 meters) in Duchikthluk Bay and deeper water (>2 meters) in Shoal Bay. The mean aboveground biomass was 39.4±4.0 grams per meter squared in Duchikthluk Bay. The eelgrass biomass was greater (67.6±11.0 grams per meter squared) in Shoal Bay, but this estimate was based on a small sample size (n=3). Seaweeds, representing six species, occurred in low abundance across both bays and were primarily associated with eelgrass. Gastropods were the most common macro-invertebrate, occurring at 45 percent of field points in Duchikthluk Bay.

Alaska↗

USGS2002

Evapotranspiration from selected fallowed agricultural fields on the Tule Lake National Wildlife Refuge, California, during May to October 2000

An investigation of evapotranspiration, vegetation quantity and composition, and depth to the water table below the land surface was made at three sites in two fallowed agricultural lots on the 15,800-hectare Tule Lake National Wildlife Refuge in northern California during the 2000 growing season. All three sites had been farmed during 1999, but were not irrigated since the 1999 growing season. Vegetation at the lot C1B and lot 6 stubble sites included weedy species and small grain plants. The lot 6 cover crop site supported a crop of cereal rye that had been planted during the previous winter. Percentage of coverage by live vegetation ranged from 0 to 43.2 percent at the lot C1B site, from approximately 0 to 63.2 percent at the lot 6 stubble site, and it was estimated to range from 0 to greater than 90 percent at the lot 6 cover crop site. Evapotranspiration was measured using the Bowen ratio energy balance technique and it was estimated using a model that was based on the Priestley-Taylor equation and a model that was based on reference evapotranspiration with grass as the reference crop. Total evapotranspiration during May to October varied little among the three evapotranspiration measurement sites, although the timing of evapotranspiration losses did vary among the sites. Total evapotranspiration from the lot C1B site was 426 millimeters, total evapotranspiration from the lot 6 stubble site was 444 millimeters, and total evapotranspiration from the lot 6 cover crop site was 435 millimeters. The months of May to July accounted for approximately 78 percent of the total evapotranspiration from the lot C1B site, approximately 63 percent of the evapotranspiration from the lot 6 stubble site, and approximately 86 percent of the total evapotranspiration from the lot 6 cover crop site. Estimated growing season precipitation accounted for 16 percent of the growing-season evapotranspiration at the lot C1B site and for 17 percent of the growing-season evapotranspiration at the lot 6 stubble and cover crop sites. The ratio of evapotranspiration rate to the reference evapotranspiration rate was strongly correlated with percentage of site coverage by vegetation at the lot C1B and lot 6 stubble sites (correlation coefficient = 0.95, sample size = 6), where percentage of site coverage was determined from quantitative vegetation surveys. It is concluded that evapotranspiration was mediated by the vegetation at all three sites, and that the differences in seasonal timing of evapotranspiration losses were caused by differences in timing of vegetation growth and development and senescence among the sites. Depth to the water table below the land surface at lot C1B ranged from 0.67 meters in early July to greater than 1.39 meters in late August. Depth to the water table at lot 6 ranged from 0.77 meter in late May to greater than 1.40 meters in late August.

Water-Resources Investigations Report↗

USGS1995

Evaluating evapotranspiration for grasslands on the Arid Lands Ecology Reserve, Benton County, and Turnbull National Wildlife Refuge, Spokane County, Washington, May 1990 to September 1991

The report evaluates evapotranspiration at four grassland sites in eastern Washington: the Snively Basin and grass lysimeter sites on the Arid Lands Ecology Reserve, and the meadow and marsh sites on the Turnbull National Wildlife Refuge. A combination of the Bowen-ratio and Penman-Monteith methods were used to estimate evapotranspiration at the sites from May 30, 1990 to September 30, 1991. The Bowen-ratio method could be used to estimate latent-heat flux during only parts of the study period. Latent heat-flux values during these periods were used in the Penman-Monteith method to estimate canopy resistance. The daily average resistance values were used to recalculate latent-heat-flux with the Penman-Monteith method for all periods. Evapotranspiration estimates made with the two methods agreed within 3 percent over the period of study. However, for the grass lysimeter site, evapotranspiration estimates made with the Bowen-ratio method were only 41 percent of those made with weighing lysimeters. A water budget from August 20, 1990 to September 30, 1991 at the Snively Basin site estimated that 101 percent of the precipitation was returned to the atmosphere as evapotranspiration. Sixteen percent of the evapotranspiration occurred from October to February, while 76 percent occurred from March to July. April accounted for over 25 percent of the evapotranspiration for the water budget period.

Washington↗

USGS2011

Adaptive management in the U.S. National Wildlife Refuge System: Science-management partnerships for conservation delivery

Adaptive management is an approach to recurrent decision making in which uncertainty about the decision is reduced over time through comparison of outcomes predicted by competing models against observed values of those outcomes. The National Wildlife Refuge System (NWRS) of the U.S. Fish and Wildlife Service is a large land management program charged with making natural resource management decisions, which often are made under considerable uncertainty, severe operational constraints, and conditions that limit ability to precisely carry out actions as intended. The NWRS presents outstanding opportunities for the application of adaptive management, but also difficult challenges. We describe two cooperative programs between the Fish and Wildlife Service and the U.S. Geological Survey to implement adaptive management at scales ranging from small, single refuge applications to large, multi-refuge, multi-region projects. Our experience to date suggests three important attributes common to successful implementation: a vigorous multi-partner collaboration , practical and informative decision framework components , and a sustained commitment to the process. Administrators in both agencies should consider these attributes when developing programs to promote the use and acceptance of adaptive management in the NWRS.

Journal of Environmental Management↗

USGS2007

Finding the Exotic Faucet Snail (Bithynia tentaculata): Investigation of Waterbird Die-Offs on the Upper Mississippi River National Wildlife and Fish Refuge

Beginning in 2002, there have been major waterbird die-offs every spring and fall in Lake Onalaska (Navigation Pool 7 of the Upper Mississippi River) located near La Crosse, Wisconsin. This area is part of the Upper Mississippi River National Wildlife and Fish Refuge (UMR Refuge) and lies within the Mississippi Flyway, through which an estimated 40 percent of the continent's waterfowl migrate. Through the 2006 spring migration, total mortality on the UMR Refuge was estimated at 22,000 to 26,000 birds, primarily American coots (Fulica americana) and lesser scaup (Aythya affinis). Two trematodes (Sphaeridiotrema globulus and Cyathocotyle bushiensis) that use the exotic faucet snail (Bithynia tentaculata) as an intermediate host were found to infect and kill the waterbirds. The faucet snail was introduced into the United States from Europe in the late 1800s. Because Lake Onalaska is a major spring and fall stop-over area for waterfowl in the Mississippi Flyway, concerns were raised that the snail and trematodes may be spreading to other waterfowl stop-over areas on the river. Exploratory sampling for faucet snails was conducted in 2005 and 2006 in navigation Pools 4-9 (excluding Pool 5a which is located between Pools 5 and 6), 11, and 13. Infected snails were found in all the sampled pools except Pool 6. To our knowledge, these are the first records of faucet snails and associated trematodes beyond those found in Pool 7, Lake Onalaska. Waterbird die-offs are becoming a UMR Refuge-wide problem. Information obtained through research and monitoring, including the identification of the origin of infections in snails and birds and the role various environmental factors have on this process, should help guide managers to develop effective mitigation and control measures.

Open-File Report↗

USGS2016

Future frequencies of extreme weather events in the National Wildlife Refuges of the conterminous U.S.

Climate change is a major challenge for managers of protected areas world-wide, and managers need information about future climate conditions within protected areas. Prior studies of climate change effects in protected areas have largely focused on average climatic conditions. However, extreme weather may have stronger effects on wildlife populations and habitats than changes in averages. Our goal was to quantify future changes in the frequency of extreme heat, drought, and false springs, during the avian breeding season, in 415 National Wildlife Refuges in the conterminous United States. We analyzed spatially detailed data on extreme weather frequencies during the historical period (1950–2005) and under different scenarios of future climate change by mid- and late-21st century. We found that all wildlife refuges will likely experience substantial changes in the frequencies of extreme weather, but the types of projected changes differed among refuges. Extreme heat is projected to increase dramatically in all wildlife refuges, whereas changes in droughts and false springs are projected to increase or decrease on a regional basis. Half of all wildlife refuges are projected to see increases in frequency (> 20% higher than the current rate) in at least two types of weather extremes by mid-century. Wildlife refuges in the Southwest and Pacific Southwest are projected to exhibit the fastest rates of change, and may deserve extra attention. Climate change adaptation strategies in protected areas, such as the U.S. wildlife refuges, may need to seriously consider future changes in extreme weather, including the considerable spatial variation of these changes.

Biological Conservation↗

USGS2004

Cabeza Prieta National Wildlife Refuge: A survey of visitor experiences: Report to respondents

In the fall of 2000, researchers from the Policy Analysis and Science Assistance Program (PASA) of the Fort Collins Science Center (FORT) in the U.S. Geological Survey (USGS) met with the staff of the Cabeza Prieta National Wildlife Refuge (CPNWR) to discuss the issues related to social, economic, and human dimensions of natural resource management as it related to the Comprehensive Conservation Plan (CCP) planning process. As a result of the meeting a research study was designed to better understand how visitors are affected by environmental management decisions and provide information to assist the refuge managers in making decisions regarding public use and recreational management related to the goals of the proposed CCP. More specifically, information was collected to document the type and frequency of visitor use; assess the importance of recreational activities; and to determine visitor attitudes about recreation management decisions within the refuge. To this end, we designed a study to assess the effects of the no-action and alternative management plans for the Refuge visitors’ perceptions and likely visitation patterns. In fall of 2002 a questionnaire was developed in collaboration with the U.S. Fish and Wildlife Service (FWS) and the CCP planning team and mailed to 1090 people who visited the refuge between June 2001 and June 2002. We used standard research methods in designing and administering the questionnaire. Six hundred and eightyfive (685) completed questionnaires (74%) were considered usable. We developed the questionnaire (OMB Control Number 1040-00) to answer the following questions: What are the important differences in visitors’ attitudes and perception regarding recreation and visitor use at CPNWR? What are the factors that explain the differences in visitor attitudes and perception regarding recreation and visitor use at CPNWR? What are the regional economic impacts of visitor spending? In general the respondents indicated support for current management practices of CPNWR. We found that people came to the Refuge to experience a connection with the resource and the environment. More than half of the respondents said that viewing the desert scenery, seeking wilderness solitude and viewing wildlife were the most important reasons for making the visit to the refuge.

Cabeza Prieta National Wildlife Refuge↗

USGS2024

Lidar estimation of storage capacity for managed water resources used by Desert Bighorn Sheep (Ovis canadensis mexicana) at Cabeza Prieta National Wildlife Refuge, Arizona

In cooperation with the U.S. Fish and Wildlife Service, the U.S. Geological Survey Southwest Biological Science Center employed ground-based light detection and ranging (lidar) during February 2022 to help meet two resource management objectives at the Cabeza Prieta National Wildlife Refuge (CPNWR), Arizona. The two objectives are (1) characterize the water storage capacity for one developed and two modified tanks, which are bedrock catchments also referred to as tinajas, that are important water sources for desert bighorn sheep ( Ovis canadensis mexicana ) in designated wilderness at the CPNWR; and (2) develop a stage-storage model to estimate water volumes from monitoring observations of water surface levels in each tank. We measured storage capacity for the three tanks identified by refuge managers, Buckhorn, Senita, and Eagle, using ground-based lidar collected during February 2022. These data produced high-resolution (centimeter scale) topographic models that improved estimates of maximum water storage capacity over previous geometry-based estimates, permitting estimations of storage capacity at multiple water surface levels (stage heights). We found that the maximum water storage capacity for the Buckhorn, Senita, and Eagle tanks was 9,108.730, 8,623.308, and 6,039.603 US gallons (gal), respectively. For each tank we report a stage-storage model based on a polynomial function that best explained variability in water storage capacity as a function of water stage height. The results presented herein will permit the CPNWR managers to (1) easily estimate water available for wildlife at any point of time, (2) interpret tank recharge following rainstorms, and (3) decide whether and when to transport water via vehicles to mechanically refill the tanks in designated wilderness.

Arizona↗

USGS2004

Comparison of detection rates of breeding marsh birds in passive and playback surveys at Lacreek National Wildlife Refuge, South Dakota

We compared detection rates of passive and playback breeding bird survey techniques on elusive marsh birds - Pied-billed Grebe (Podilymbus podiceps), American Bittern (Botaurus lentiginosus), Least Bittern (Ixobrychus exilis), Virginia Rail (Rallus limicola), and Sora (Porzana carolina) - during a two-year study at Lacreek National Wildlife Refuge, in southwestern South Dakota. We conducted 151 passive point counts followed by playback-response surveys at the same points in marsh-bird habitat on the refuge. Playback surveys detected secretive water birds more frequently than our passive surveys, increasing rates for each species by factors of 2.4 to 7.0. The distance a bird was detected from a point varied with the species and the survey technique.

South Dakota↗

USGS2024

Bees of the Buenos Aires National Wildlife Refuge—A preliminary report on a bee survey in a vulnerable semi-desert grassland of the Sonoran Desert

Pollinators are vital to the continued existence and seed production of about 87.5 percent of all flowering plants (Ollerton and others, 2011). In the semi-desert grasslands of Buenos Aires National Wildlife Refuge, in the Sonoran Desert of the United States, flowering forbs provide seed vital to the food base of wildlife, including the 136 species of resident and migratory birds using the Refuge’s grasslands and, notably, the endangered Colinus virginianus ridgwayi (masked bobwhite quail) for which the Refuge was established. The Sonoran Desert is known for its high diversity of native bees, but these pollinators have not been extensively described at the Refuge. We conducted a survey of native bees at the Refuge from late May 2019 through early February 2020. Of all bees collected, we subsampled, curated, and identified over 3,300 bees representing 39 genera within four families (Andrenidae, Apidae, Halictidae, Megachilidae). For about 8 percent of the sampled bees, we further identified 36 species and several potentially new, undescribed species using either visual or deoxyribonucleic acid (DNA) barcoding methods. Sampling was done using bee bowls and blue-vane traps. Our initial results suggest the Refuge is species rich in native bees and supports diverse bee faunas across subtle differences in plant composition and location within the Refuge. Continued survey, inventory, and focused monitoring of the bee populations of the Refuge will be valuable in understanding the relationship of bee populations with the health and productivity of seed-bearing plants, effect of prescribed fire on bee fauna, the ongoing dynamics of bee-plant interactions, and how the bee pollinator community of the Refuge is responding to stressors, such as invasive species proliferation and changing climate conditions.

Arizona↗

USGS2005

Visitor and community survey results for Kilauea Point National Wildlife Refuge and Lighthouse: Completion report

The U.S. Fish and Wildlife Service (USFWS) and the Central Federal Lands Highway Division of the Federal Highway Administration, U.S. Department of Transportation are currently pursuing the planning and potential design of an alternative transportation system (ATS) for Kilauea Point National Wildlife Refuge (Refuge or Kilauea Point NWR). The USFWS and CFLHD seek an alternative transportation solution that provides the highest quality visitor experience and is sensitive to biological and cultural resources and the needs of the local community. In planning the alternative transportation system, managers need to consider how an ATS would change factors such as visitor access, visitor experience, visitor willingness to pay, and visitor net economic benefits. The Policy Analysis and Science Assistance branch (PASA) at the U.S. Geological Survey Fort Collins Science Center is dedicated to studying relations between humans and the environment. The objective of PASA is to conduct studies to understand how humans are affected by environmental management decisions and how human activities impact use and conservation of natural resources.

Hawaii↗