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At least 937 records · Page 52Linked to original sources
USGS2016

Changes in the prevalence of avian disease and mosquito vectors at Hakalau Forest National Wildlife Refuge: a 14-year perspective and assessment of future risk

Throughout the main Hawaiian Islands, introduced mosquito-borne disease has had, and continues to have, a profound impact on the distributions and abundance of native Hawaiian forest birds. Populations of remaining native forest birds are largely restricted to high elevation forests where mean temperatures are marginal for vector and parasite development and limited availability of larval mosquito habitat constrains mosquito populations and disease transmission. Hakalau Forest National Wildlife Refuge (HFNWR) was established for the preservation of endemic avifauna in 1985. Since its creation, native bird communities there have remained intact and most species populations are stable or increasing. However, avian malaria had been detected at HFNWR in the past and, in light of documented climate change, new concerns have been raised regarding the long-term fate of the refuge’s forest birds. To examine the possible changes in avian malaria transmission at HFNWR we sampled forest birds for blood parasites, trapped adult mosquitoes and surveyed larval mosquito habitat at three sites during 2012 and compared our results with similar data collected between 1998 and 1999. We tested blood samples by polymerase chain reaction (PCR), immunoblotting, and microscopy to determine prevalence of acute and chronic infection and used attractive gravid traps to sample the vector mosquito Culex quinquefasciatus. Our study documented spatial trends and temporal changes in the prevalence of avian malaria, mosquito presence, larval mosquito habitat and feral pig activity at HFNWR. We found evidence of local transmission in high elevation forests, a general pattern of increasing prevalence at lower elevations and along a South to North gradient and a two-fold decrease in the prevalence of avian malaria in the intervening 14 years. Despite considerable effort, we were unable to detect larval C. quinquefasciatus and captured only one adult indicating that the vector of avian malaria has a very limited presence at HFNWR. We did, however, document the establishment of another invasive mosquito, Aedes japonicus japonicus , and its occurrence in tree fern cavities and rock pools as larval habitat in the lower forests of HFNWR. We suggest that interspecific competition by A. j. japonicus and predation by a suite of native predators may provide biotic resistance to the establishment of permanent C. quinquefasciatus populations. While current predictions of climate change in the Hawaiian Islands include a gradual warming and enhanced transmission by mid-century, the current cooling trend recorded at high elevation HFNWR illustrates the importance of monitoring to document fine scale temporal and site specific changes in prevalence. Long term changes in precipitation may have a more profound effect on local transmission of malaria than temperature and we may have already seen some potential impacts of an extended drought at HFNWR with a decrease in feral pig activity and pig associated larval mosquito habitat and increases in stream-associated larval mosquito habitat.

Hawaii↗
USGS2016

Federal collaboration in science for invasive mammal management in U.S. National Parks and Wildlife Refuges of the Pacific Islands

Some of the most isolated islands in the Pacific Ocean are home to US National Parks and Wildlife Refuges. These islands are known for flora and fauna that occur nowhere else, but also for invasive species and other factors which have resulted in the disproportionate extinction of native species. The control of invasive mammals is the single most expensive natural resource management activity essential for restoring ecological integrity to parks in the Hawaiian Islands, American Samoa, and the islands of Guam and Saipan. Science-based applications supporting management efforts have been shaped by longstanding collaborative federal research programs over the past four decades. Consequently, feral goats (Capra hircus) have been removed from >690 km2 in National Parks, and feral pigs (Sus scrofa) have been removed from >367 km2 of federal lands of Hawai‘i, bringing about the gradual recovery of forest ecosystems. The exclusion of other non-native ungulates and invasive mammals is now being undertaken with more sophisticated control techniques and fences. New fence designs are now capable of excluding feral cats (Felis catus) from large areas to protect endangered native waterfowl and nesting seabirds. Rodenticides which have been tested and registered for hand and aerial broadcast in Hawai‘i have been used to eradicate rats from small offshore islands to protect nesting seabirds and are now being applied to montane environments of larger islands to protect forest birds. Forward-looking infrared radar (FLIR) is also being applied to locate wild ungulates which were more recently introduced to some islands. All invasive mammals have been eradicated from some remote small islands, and it may soon be possible to manage areas on larger islands to be free of invasive mammals at least during seasonally important periods for native species.

Conference Paper↗
USGS2006

Efficacy of feral pig removals at Hakalau Forest National Wildlife Refuge

We compiled and analyzed data from 1987–2004 on feral pig ( Sus scrofa ) management and monitoring activities at Hakalau Forest National Wildlife Refuge, a tropical montane rainforest on the island of Hawai`i. These data included annual surveys of feral pig and cattle ( Bos taurus ) activity, the number of feral ungulates removed from closed management units, age and reproductive status from necropsies, and vegetation surveys repeated 4 times over a 16 year period. We found an essentially even sex ratio within the feral pig population and within age classes, although males lived to 60 months while females lived to only 48 months. The pregnancy rate was 23.5%, and lactation rate was 8.3%, regardless of season and age, but lactation peaked in April-June. Reproductive rates also increased with age, peaking at 2–4 years in females. We reconstructed the standing population within a closed unit to examine demographic processes. We estimated that annual removal in excess of approximately 41–43% would be necessary to affect a population decline. We examined annual feral pig activity surveys and found a strong and sustained decline in pig sign after 1997 relative to unmanaged areas. We related the standing population to feral pig activity surveys to build a predictive model of feral pig density, and then applied this model to other management units. We evaluated control methods and found snaring to be more efficient than staff or public hunting. Vegetation monitoring revealed a strong temporal increase in cover of native ferns, and marginally non-significant decreases in cover of bryophytes and exposed soil.

Hawai'i↗
USGS2002

Monitoring and assessment of juvenile steelhead on Toppenish National Wildlife Refuge. Quick Response Project for 2001

Toppenish National Wildlife Refuge (TNWR) in south central Washington was established in 1964 to provide an important link in the chain of feeding and resting areas for waterfowl and other migratory birds using the Pacific Flyway. Wetlands on TNWR include both natural floodplain wetlands along Toppenish Creek and man-made impoundments designed to mimic natural floodplain processes. Wetland improvement projects were completed between 1995-1998 to restore wetland habitat conditions and eliminate monotypic stands of invasive reed canary grass. Habitat improvements boosted fall/winter use from 2,000 to 50,000 waterfowl, and increased overall use by many species of water birds, shorebirds, and other migratory birds. Increased use by bald eagles, peregrine falcons, and willow flycatchers has also been recorded.

Washington↗
USGS2002

Extracting temporal and spatial information from remotely sensed data for mapping wildlife habitat: Tucson

The research accomplished in this dissertation used both mathematical and statistical techniques to extract and evaluate measures of landscape temporal dynamics and spatial structure from remotely sensed data for the purpose of mapping wildlife habitat . By coupling the landscape measures gleaned from the remotely sensed data with various sets of animal sightings and population data , effective models of habitat preference were created. Measures of temporal dynamics of vegetation greenness as measured by National Oceanographic and Atmospheric Administration’s Advanced Very High Resolution Radiometer (AVHRR) satellite were used to effectively characterize and map season specific habitat of the Sonoran pronghorn antelope, as well as produce preliminary models of potential yellow-billed cuckoo habitat in Arizona. Various measures that capture different aspects of the temporal dynamics of the landscape were derived from AVHRR Normalized Difference Vegetation Index composite data using three main classes of calculations: basic statistics, standardized principal components analysis, and Fourier analysis. Pronghorn habitat models based on the AVHRR measures correspond visually and statistically to GIS-based models produced using data that represent detailed knowledge of ground-condition. Measures of temporal dynamics also revealed statistically significant correlations with annual estimates of elk population in selected Arizona Game Management Units, suggesting elk respond to regional environmental changes that can be measured using satellite data . Such relationships, once verified and established, can be used to help indirectly monitor the population. Measures of landscape spatial structure derived from IKONOS high spatial resolution (1-m) satellite data using geostatistics effectively map details of Sonoran pronghorn antelope habitat . Local estimates of the nugget, sill, and range variogram parameters calculated within 25 x 25-meter image windows describe the spatial autocorrelation of the image, permitting classification of all pixels into coherent units whose signature graphs exhibit a classic variogram shape. The variogram parameters captured in these signatures have been shown in previous studies to discriminate between different species-specific vegetation associations. The synoptic view of the landscape provided by satellite data can inform resource management efforts. The ability to characterize the spatial structure and temporal dynamics of habitat using repeatable remote sensing data allows closer monitoring of the relationship between a species and its landscape.

Arizona↗
USGS1998

Satellite telemetry: A new tool for wildlife research and management

The U.S. Fish and Wildlife Service and the Alaska Department of Fish and Game have cooperated since 1984 to develop and evaluate satellite telemetry as a means of overcoming the high costs and logistical problems of conventional VHF (very high frequency) radiotelemetry systems. Detailed locational and behavioral data on caribou ( Rangifer tarandus ), polar bears ( Ursus maritimus ), and other large mammals in Alaska have been obtained using the Argos Data Collection and Location System (DCLS). The Argos system, a cooperative project of the Centre National d'Études Spatiales of France, the National Oceanic and Atmospheric Administration, and the National Aeronautics and Space Administration, is designed to acquire environmental data on a routine basis from anywhere on earth. Transmitters weighing 1.6-2.0 kg and functioning approximately 12-18 months operated on a frequency of 401.650 MHz. Signals from the transmitters were received by Argos DCLS instruments aboard two Tiros-N weather satellites in sun-synchronous, nearpolar orbits. Data from the satellites were received at tracking stations, transferred to processing centers in Maryland and France, and made available to users via computer tape, printouts, or telephone links. During 1985 and 1986, more than 25,000 locations and an additional 28,000 sets of sensor data (transmitter temperature and short-term and long-term indices of animal activity) were acquired for caribou and polar bears. Locations were calculated from the Doppler shift in the transmitted signal as the satellite approached and then moved away from the transmitter. The mean locational error for transmitters at known locations (n - 1,265) was 829 m; 90% of the calculated locations were within 1,700 m of the true location. Caribou transmitters provided a mean of 3.1 (+5.0. SD) locations per day during 6h of daily operation, and polar bear transmitters provided 1.7 (+6.9SD) locations during 12h of operation every third day. During the first 6 months of operation, the UHF (ultra-high frequency) signal failed on three of 32 caribou transmitters and 10 of 36 polar bear transmitters. A geographic information system (GIS) incorporating other databases (e.g., land cover, elevation, slope, aspect, hydrology, ice distribution) was used to analyze and display detailed locational and behavioral data collected via satellite. Examples of GIS applications to research projects using satellite telemetry and examples of detailed movement patterns of caribou and polar bears are presented. This report includes documentation for computer software packages for processing Argos data and presents developments, as of March 1987, in transmitter design, data retrieval using a local user terminal, computer software, and sensor development and calibration.

Resource Publication↗
USGS2008

A low intensity sampling method for assessing blue crab abundance at Aransas National Wildlife Refuge and preliminary results on the relationship of blue crab abundance to whooping crane winter mortality

We sampled blue crabs ( Callinectes sapidus ) in marshes on the Aransas National Wildlife Refuge, Texas from 1997 to 2005 to determine whether whooping crane ( Grus americana ) mortality was related to the availability of this food source. For four years, 1997 - 2001, we sampled monthly from the fall through the spring. From these data, we developed a reduced sampling effort method that adequately characterized crab abundance and reduced the potential for disturbance to the cranes. Four additional years of data were collected with the reduced sampling effort methods. Yearly variation in crab numbers was high, ranging from a low of 0.1 crabs to a high of 3.4 crabs per 100-m transect section. Mortality among adult cranes was inversely related to crab abundance. We found no relationship between crab abundance and mortality among juvenile cranes, possibly as a result of a smaller population size of juveniles compared to adults.

Texas↗
USGS2018

Establishing a baseline: the amphibians of Lower Suwannee National Wildlife Refuge, Dixie and Levy counties, Florida

From 2002-2006, we used a variety of sampling techniques to survey the amphibians and water chemistry of Lower Suwannee National Wildlife Refuge in Florida’s Big Bend region. We recorded 23 amphibian species, 19 frogs and 4 salamanders. Species richness was lower than in other areas of the coastal Big Bend region to the north, perhaps due to a combination of proximity to the limits of species’ ranges, sampling techniques, times of year when sampling occurred, and variation in detection probabilities among years and regions. Amphibians occupied a wide variety of habitats and appeared tolerant of the generally acidic conditions of many of the wetlands. Small streams and the Suwannee River were less acidic and had greater conductivities and mineral concentrations than isolated ponds; concentrations of heavy metals varied and mercury was not detected. Although additional species may yet be found in LSNWR, this survey provides a historic baseline for assessing future status and trends of amphibian populations as areas adjacent to the refuge are disturbed and as restoration and multi-use management continue within its boundaries.

Florida↗
USGS2018

Biodiversity of amphibians and reptiles at the Camp Cady Wildlife Area, Mojave Desert, California and comparisons with other desert locations

We examined the biodiversity of amphibian and reptile species living in and near constructed ponds in the riparian area at the Camp Cady Wildlife Area (CCWA) in the Mojave Desert of San Bernardino County, California, based on field work from 1998-1999, 2016-2017, review of the literature, and searches for museum specimens using VertNet.org. A total of 11 species (201 captures), including two frogs and toads (one non-native frog), one turtle, three snakes, and five lizards were captured at terrestrial drift fences with pitfall traps encircling two ponds (0.5 hectares total) on the property in 1999. Four additional species (one frog, one lizard, and two snakes) were previously reported in 1978 from a ranch 1.6 km southwest from CCWA for a total of 15 species in the local area. The southwestern pond turtle (Actinemys pallida), was commonly observed at CCWA from 1998 to 1999 and documented as a breeding population. However, the species was extirpated at CCWA sometime after 2014 when the last individuals were photographed, and none have been detected since then despite significant efforts to do so. Biodiversity of amphibians and reptiles at CCWA is relatively low compared with sites elsewhere in the Mojave Desert with more elevational diversity. The 14 native species documented at CCWA accounts for approximately 21% of the native reptile and amphibian species reported by Stewart (1994) for the entire Mojave Desert, including peripheral species. Our smaller sample likely represents a group of easily detected species and is biased toward those found in or near water, especially amphibians. However, the relative proportion of amphibians vs. reptiles that inhabited CCWA in the last 40 years is not significantly different from the recently compiled proportions at five military installations in the California deserts. The herpetofauna inhabiting CCWA is notable for including riparian obligates like the western toad (Anaxyrus boreas), Northern Baja California treefrog (Pseudacris h. hypochondriaca), and A. pallida that are otherwise absent from large portions of the Mojave Desert. Other species are typical of those that are expected in the low-elevation creosote scrubdominated ecosystem in the area.

California↗
USGS1999

Atlantic white cedar plantings in St. Tammany Parish, Louisiana, and the Bogue Chitto National Wildlife Refuge, Mississippi

Populations of Atlantic white cedar (Chamaecyparis thyoides (L.) B.S.P.) growing at the extreme western range of the species are in danger of being lost, and information on the ecology of these populations is limited. Seeds and seedlings ("wildlings") were collected near Vancleave, MS. The wildlings were transplanted to bay-head sites on Bogue Chitto National Wildlife Refuge where canopy gaps had been created in early 1989. Seeds were germinated, grown in a greenhouse, and transplanted a year later to three locations within a slash pine plantation: a bedded and fertilized site, the margin of a cypress pond, and a wet gap, in St. Tammany Parish, Lousiana. These plantings were established to study survival and growth in different habitat types, to compare seedlings grown from seed versus transplanted wildlings, and to attempt to generate some interest in planting Atlantic white-cedar in the extreme western portion of its natural range. Overall seedling survival averaged 94 percent after five growing seasons, although significant differences were detected among sites. Mean height per site in 1994 was significantly greater at the bedded and fertilized site (233 centimeters), and lowest at the slash pine site (91 centimeters). Growth at the cypress pond site was intermediate (158 centimeters). Wildlings at the bay-head sites had lower survival rates (75 and 64 percent), but average heights for the two sites were similar to those of the seedlings (265 and 165 centimeters). These results show that plantings involving either local seed or wildlings are viable choices for regenerating Atlantic white-cedar in southern Mississippi and eastern Louisiana.

Louisiana; Mississippi↗
USGS2019

Value of migratory bird recreation at the Bosque del Apache National Wildlife Refuge in New Mexico

Each fall, thousands of Rocky Mountain Sandhill Cranes and other migratory birds congregate at the Bosque del Apache National Wildlife Refuge in New Mexico’s Rio Grande Valley in search of wintering habitat. As such, this refuge is known as one of the premier destinations for bird viewing and photography in the United States. Using contingent valuation data, this case study quantifies the value associated with migratory bird recreation at this refuge to be \$7.5 million in 2010. It is estimated that this annual value increased by more than \$6.4 million in 2017 due to growth in annual refuge visitation.

New Mexico↗
USGS1990

Coastal mapping programs at the U.S. Fish and Wildlife Service's National Wetlands Research Center

Over the past 10 years, the U.S. Fish and Wildlife Service's (FWS) National Wetlands Research Center (center; formerly the National Coastal Ecosystems Team) has been continuously involved in the production of maps for use by coastal decision makers. The types of maps produced by the center have been national, regional, or local in scope depending on user needs. Map scales have ranged from 1:24,000 to 1:250,000. Themes depicted have included biological resources, including wetlands and seagrasses; upland habitat or land use; water resources such as water quality, bathymetry, and salinity; cultural features such as ownership, archaeological sites, and dredge-spoil disposal areas; and soils and landforms. We present overviews on the various mapping programs of the center. We highlight efforts such as the ecological inventories of the Atlantic, Gulf, and Pacific coasts; the ecological characterization atlases of the Gulf of Mexico; and the large scale (1:24,000) habitat maps of various coastal regions of the United States. Center methods and techniques are discussed, including the collaborative efforts between the center and FWS's National Wetlands Inventory for updating wetland maps and adding upland and seagrass bed delineations to inventory maps. We also make recommendations for future coastal ecosystem mapping programs that use conventional and automated mapping methodologies, such as geographic information systems and image processing.

Biological Report↗
USGS2022

Forest bird populations at the Big Island National Wildlife Refuge Complex, Hawai‘i

Endemic Hawaiian forest birds have experienced dramatic population declines. The Big Island National Wildlife Refuge Complex (BINWRC) was created for conservation of endangered Hawaiian forest birds and their habitats. Surveys have been conducted at two units of BINWRC to monitor forest bird populations and their response to management actions. We analyzed survey data from 1987 to 2019 at the Hakalau Forest Unit (HFU) and from 1995 to 2019 at the Kona Forest Unit (KFU). We analyzed three strata at HFU: open-forest, closed-forest, and pasture, and two strata at the KFU: upper (>1524 m elevation) and lower (<1524 m). In all years, ‘i‘iwi (Drepanis coccinea), ‘apapane (Himatione sanguinea), and Hawai‘i ‘amakihi (Chlorodrepanis virens virens) were the most abundant species at HFU. The three endangered forest bird species, Hawai‘i ‘ākepa (Loxops coccineus), ‘alawī (Loxops mana, also known as Hawai‘i creeper) and ‘akiapōlā‘au (Hemignathus wilsoni), had much lower densities. The most abundant species at KFU was ‘apapane, followed by Hawai‘i ‘amakihi and warbling white-eye (Zosterops japonicus) at much lower densities. At HFU we found a continuation of several trends observed in previous analyses from 1987–2012, with most species’ trends upward in pasture stratum, stable in the open-forest stratum, and downward in the closed-forest stratum. However, when we looked at the most recent decade at HFU, more species were showing downward trends in all three strata. At KFU results were mixed, with more species’ trends downward in the upper stratum and more species’ trends upward in the lower stratum. Populations of endangered forest species were either locally extirpated at KFU or in numbers too low to reliably estimate population densities. Both units in the BINWRC are important for conservation of forest birds on Hawai‘i Island, and our results show that HFU supports the majority of the three endangered forest bird species found on Hawai‘i Island. Our analysis also shows the importance of continuous monitoring and timely analysis to track forest bird populations. With the additional data provided by continued surveys, we determined conclusive population trends for species whose trends were previously inconclusive. Knowing current population densities, abundances, and trends allows managers to evaluate and adapt management actions to support forest bird conservation at the BINWRC.

Hawaii↗
USGS2022

Aerial dispersal of Lygodium microphyllum spores within Arthur R. Marshall Loxahatchee National Wildlife Refuge

Native across the Old World tropics from Africa to Southeast Asia and Australia, Lygodium microphyllum (Cav.) R. Br. (Old World Climbing Fern) is one of the most invasive plant species threatening South Florida ecosystems (Rodgers et al. 2014). This invasive fern was first collected as a naturalized plant in South Florida in the late 1960s (Beckner 1968). Subsequent populations were observed in the late 1970s in both Martin and Palm Beach Counties (Nauman and Austin 1978). In 1989 L. microphyllum was observed by the South Florida Water Management District (SFWMD) in the Arthur R. Marshall Loxahatchee National Wildlife Refuge (LNWR). In 1995, a survey by SFWMD indicated that 12% of LNWR was colonized by L. microphyllum. By 1997 this had increased to 36% (Ferriter 2001). Ten years later, Systematic Reconnaissance Flights conducted over LNWR estimated that 44% of LNWR had sparse (> a single individual tree, shrub or stem to <50%) or dense (>50%) infestations of L. microphyllum

Florida Scientist↗
USGS2022

Three steps to minimize wildlife disease transmission via construction equipment

Aquatic wildlife can be harmed by viruses, bacteria, fungi, and parasites introduced into wetlands. These infectious pathogens can survive in mud, soil, vegetation, and other debris that collect on the bodies and crevices of drivable equipment. Construction and habitat restoration projects can accidentally transport pathogens from a contaminated aquatic habitat into a healthy one. These three steps can help minimize the spread of pathogens to amphibians, reptiles, and fishes. The information provided in this fact sheet has been extracted from the publication, "Minimizing the Spread of Herpetofaunal Pathogens in Aquatic Habitats by Decontaminating Construction Equipment " (http://northeastparc.org/wp-content/uploads/2021/01/Julian-2020-Decontamination-for-Herps-for-large-equipment.pdf)

Report↗
USGS2022

Host plant associations of Lepidoptera and implications for forest bird management at Hakalau Forest National Wildlife Refuge

Forests dominated or co-dominated by ‘ōhi‘a ( Metrosideros polymorpha ) are critical to most Hawaiian forest birds, but fungal diseases causing Rapid ‘Ōhi‘a Death (ROD) threaten ‘ōhi‘a-based food webs that support native bird communities on Hawai‘i Island. Caterpillars are the most frequently consumed arthropod prey of native birds and their young and are especially frequent in the diets of one threatened (T) and three endangered (E) species (“listed” species) at Hakalau Forest National Wildlife Refuge (Hakalau): ‘akiapōlā‘au ( Hemignathus wilsoni , E), ‘alawī (Hawai‘i creeper; Loxops mana , E), Hawai‘i ‘ākepa ( L. coccineus , E), and ‘i‘iwi ( Drepanis coccinea , T). Hakalau harbors the largest and most stable populations of listed forest birds in Hawai‘i, presumably due to the availability of food resources and the extent of suitable, managed habitat above the range of mosquito-borne avian malaria. Because a previous study indicated that only a few caterpillar species were important in the diets of listed birds at Hakalau, we investigated the distribution of caterpillars on common host plants available to foraging birds. Eleven native plant species hosted two or more taxa identified to genus or species, with at least seven from ‘ōhi‘a, six from koa ( Acacia koa ), and five from ‘ākala ( Rubus hawaiensis ). We identified 16 taxa to genus or species from 9 families, assigning 11 to species. Leaves, which were the focus of our sampling effort, were the substrate used by 20 caterpillar taxa, and dead wood or bark was used by 7 taxa. In a previous study, we classified 19 morphotypes of caterpillar mandibles in the diets of native and alien birds at Hakalau, and in the present study we dissected mandibles from caterpillars that likely matched 10 of those morphotypes. These 10 morphotypes potentially represented >95% of caterpillar prey found in the earlier diet study and were collected from 11 host plant species, with ‘ōhi‘a hosting 8 morphotypes, 4 of which were exclusive to ‘ōhi‘a. The most widely hosted morphotype was found on all 11 plant species that we sampled, including ‘ōhi‘a, but the other 9 morphotypes were found on 1–7 hosts. As shown by the previous diet study, each of the listed bird species consumed caterpillar prey consisting mostly of combinations of two morphotypes drawn from a pool of only five, indicating a high degree of specialization. In the present study, we collected three of the five key morphotypes only on ‘ōhi‘a, highlighting the importance of this tree to listed bird species. Because ‘ōhi‘a forests in Hakalau remain vulnerable to ROD, measures to mitigate the impacts of reduced ‘ōhi‘a cover are important to consider from the perspective of forest bird food webs and diet. Ongoing reforestation of former pasturelands with koa and common understory species should provide alternative caterpillar prey for forest birds. Our results and information from the literature indicate that koa supports, to varying degrees, nearly all forest birds at Hakalau, while ‘ākala, ‘ōhelo ( Vaccinium calycinum ), kōlea ( Myrsine lessertiana ), ‘ōlapa ( Cheirodendron trigynum ), pūkiawe ( Leptecophylla tameiameiae ), and māmaki ( Pipturus albidus ) could benefit bird populations by increasing prey availability and structural complexity in koa-dominated stands. Foraging studies and additional research to identify species and host plant associations of important forest bird prey, including caterpillars and other arthropods, can help managers evaluate the complex interactions between native forest birds and their food webs and habitats.

Hawaii↗
USGS2023

Creating an updated vegetation map for Big Oaks National Wildlife Refuge: Final report

Although Big Oaks NWR encompasses much diversity in wildlife species, an up-to-date, detailed, and comprehensive map showing vegetation types was lacking. The creation of an updated vegetation map for Big Oaks NWR was approved in early 2019. Digital aerial imagery was collected on November 1, 2019 at a resolution of 0.15 meter per pixel using four spectral bands: red, green, blue, and near infrared. A mapping classification was developed in collaboration with refuge managers to reflect the vegetation present at Big Oaks NWR.

Indiana↗
USGS2023

Mangrove habitat persistence and carbon vulnerability associated with increased nutrient loading and sea-level rise at Ding Darling National Wildlife Refuge (Sanibel Island, Florida, USA)

J.N. “Ding” Darling National Wildlife Refuge (DDNWR) is located on Sanibel Island along the southwestern coast of Florida, USA. Sanibel Island is heavily developed, but DDNWR provides protection for a large mangrove area that supports biodiversity and recreational opportunity. However, nitrogen (N) and phosphorus (P) eutrophication attributed to agriculture discharge along the Caloosahatchee River has affected the area’s aquatic habitat with algal blooms and may be causing untimely degradation of Sanibel’s mangrove forests. We launched a series of studies to understand how additional nutrient loading to the levels expected in the future might affect DDNWR’s mangrove resource. We experimentally fertilized selected mangrove forest areas with N fertilizer (+N; NH4) and P fertilizer (+P; P 2 O 5 ) for three years, and monitored soil surface elevation change, soil and pneumatophore CO 2 fluxes from respiration, mangrove tree sap flow from two species ( Avicennia germinans , Rhizophora mangle ), and individual tree and stand water use, from which we developed carbon (C) budgets for +N and +P vs. control simulations as applied to DDNWR’s 1112 ha mangrove area. Many of the measured response variables provided hints of subtle changes in response to +P rather than +N, which were compounded when scaled. From this, we found that additional P loading is expected to stimulate CO 2 uptake via net ecosystem exchange of C, likely pressing the system beyond metabolic capacity and leading to a projected 41% increase in lateral C export to the estuary. Additional lateral C export is concomitant to a reduction in vertical soil surface elevation with +P. Furthermore, an inability of DDNWR’s mangroves to bury additional P and a release of P-bound ions to lateral export may exacerbate estuarine eutrophication. We also modelled the effect of sea-level rise influences on DDNWR’s mangroves through 2100 using a soil cohort model (WARMER-Mangroves) and found that the mangroves may be resilient to current rates of sea-level rise into the future but may also be susceptible to moderate accelerations. Greater eutrophication could create additional vulnerabilities to mangrove submergence, especially to basin mangroves where P concentrations are high and already reducing soil surface elevations in some mangroves. Our results suggest that amelioration of current P concentrations and avoidance of additional P loading to Sanibel Island’s mangroves are management options to consider.

Florida↗