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At least 1,351 records · Page 75Linked to original sources
USGS2007

Viability criteria for steelhead of the south-central and southern California coast

Recovery planning for threatened and endangered steelhead requires measurable, objective criteria for determining an acceptably low risk of extinction. Here we propose viability criteria for two levels of biological organization: individual populations, and groups of populations within the SouthCentral/Southern California Coast Steelhead Recovery Planning Domain. For populations, we adapt criteria commonly used by the IUCN (The World Conservation Union) for identifying at-risk species. For groups of populations we implement a diversity-based “representation and redundancy rule,” in which diversity includes both life-history diversity and biogeographic groupings of populations. The resulting criteria have the potential for straightforward assessment of the risks posed by evolutionary, demographic, environmental, and catastrophic factors; and are designed to use data that are readily collected. However, our prescriptive approach led to one criterion whose threshold could not yet be specified due to inadequate data, and others in which the simplicity of the criteria may render them inefficient for populations with stable run sizes or stable life-history polymorphisms. Both of these problems could likely be solved by directed programs of research and monitoring aimed at developing more efficient (but equally risk-averse) “performance-based criteria.” Of particular utility would be data on the natural fluctuations of populations, research into the stabilizing influence of life-history polymorphisms, and research on the implications of drought, wildfires, and fluvial sediment regimes. Research on estuarine habitat could also yield useful information on the generality and reliability of its role as nursery habitat. Currently, risk assessment at the population level is not possible due to data deficiency, highlighting the need to implement a comprehensive effort to monitor run sizes, anadromous fractions, spawner densities and perhaps marine survival. Assessment at the group level indicates a priority for securing inland populations in the southern Coast Ranges and Transverse Ranges, and a need to maintain not just the fluvial-anadromous life-history form, but also lagoon-anadromous and freshwater-resident forms in each population.

Report↗
USGS1995

Pinyon-juniper woodlands

Pinyon-juniper woodlands are one of the largest ecosystems in the Southwest and in the Middle Rio Grande Basin (Fig. 1). The woodlands have been important to the region's inhabitants since prehistoric times for a variety of natural resources and amenities. The ecosystems have not been static; their distributions, stand characteristics, and site conditions have been altered by changes in climatic patterns and human use and, often, abuse. Management of these lands since European settlement has varied from light exploitation and benign neglect, to attempts to remove the trees in favor of forage for livestock, and then to a realization that these lands contain useful resources and should be managed accordingly. Land management agencies are committed to ecosystem management. While there are several definitions of ecosystem management, the goal is to use ecological approaches to create and maintain diverse, productive, and healthy ecosystems (Kaufmann et al. 1994). Ecosystem management recognizes that people are an integral part of the system and that their needs must be considered. Ecological approaches are central to the concept, but our understanding of basic woodland ecology is incomplete, and there are different opinions and interpretations of existing information (Gottfried and Severson 1993). There are many questions concerning proper ecosystem management of the pinyon-juniper woodlands and how managers can achieve these goals (Gottfried and Severson 1993). While the broad concept of ecosystem management generally is accepted, the USDA Forest Service, other public land management agencies, American Indian tribes, and private landowners may have differing definitions of what constitutes desired conditions. Key questions about the pinyon-juniper ecosystems remain unanswered. Some concern the basic dynamics of biological and physical components of the pinyon-juniper ecosystems. Others concern the distribution of woodlands prior to European settlement and changes since the introduction of livestock and fire control. This relates to whether tree densities have been increasing or whether trees are invading grasslands and, to a lesser extent, drier ponderosa pine (Pinus ponderosa) forests. In areas where woodlands were heavily used by American Indians for fuelwood prior to European contact, the advance of pinyon and juniper could represent the slow recovery from intensive use (Samuels and Betancourt 1982). There are numerous questions regarding declines in watershed condition related to changes in pinyon-juniper tree stand densities and to the density and composition of understory vegetation. There are different opinions about proper management of woodland ecosystems. Should these lands be managed for a single resource, such as forage for livestock production, or managed for sustained production of multiple resource products and amenities? Depending on site and stand conditions, the woodlands can produce variable quantities of fuelwood, pinyon nuts, wildlife habitat, forage for livestock, and cover for watershed protection. Management must also consider increasing recreational demands, threatened and endangered species, and protection of archeological sites. Many pinyon-juniper woodland watersheds in New Mexico have unsatisfactory soil and watershed conditions (USDA Forest Service 1993); managers must develop restoration procedures that recognize the value of woodland ecosystems. The concerns, questions, and conflicts surrounding management of pinyon-juniper lands, as well as the ecological foundations of ecosystem management, require that all interested parties reevaluate attitudes toward the woodlands. Ecosystem management goals and concepts recognize diversity. Pinyonjuniper woodlands are diverse, and stand characteristics and site productivities vary. Management objectives and prescriptions must evaluate the potential of each site, and decisions must be based on sound scientific information. This information is often unavailable. Therefore, this paper describes what we do know about the characteristics, distribution, and ecology of pinyon-juniper woodlands, including the effects of natural and human factors, within the southwestern United States and particularly the Middle Rio Grande Basin. It also reviews some past and present management options in this widespread and important vegetation type. The review draws on research and management information from the Rio Grande Basin and from similar areas in the Southwest and adjacent regions. It does not attempt to review all of the relevant literature; additional sources can be found within the articles cited in the References.

General Technical Report↗
USGS1985

Population biology of bluegills, Lepomis macrochirus, in lotic habitats on the irrigated San Joaquin Valley floor

Rapid expansion of irrigated agriculture in the western United States has prompted concerns for aquatic resources. Although the impacts of irrigation activities on quality and quantity of river water are well documented (e.g., high turbidity from soil erosion, eutrophication from nutrient runoff, pesticide contamination, reduced dis- charge), their effects on fish populations are still poorly understood. We studied the food, growth, and relative weight (a measure of body condition) of bluegills, Lepo- mis macrochirus, in relation to environmental factors in reaches of the San Joaquin and Merced rivers that have been affected to varying degrees by irrigation return flows. Fry of bluegills ate mostly cladocerans and copepods; fingerlings and larger fish ate immature aquatic insects, terrestrial insects, amphipods, and mollusks. Bluegill stomachs were fuller and contained a higher diversity of forage taxa in habitats with low turbidity and conductivity, weak buffering capacity, and low nutrient levels; bluegills also ate a more diverse diet where the potential forage supply (benthic macroinvertebrates) was most diverse. Bluegills attained mean total lengths of about 42 mm at age I, 86 mm at age 11, 116 mm at age III, 153 mm at age IV, and 166 mm at age V. Mean relative weight ranged from 96-111. Growth rate and relative weight were not significantly correlated with environmental or dietary variables. On the basis of our study, we concluded that environmental degradation from irrigation activities affected the diet of bluegills primarily by modifying the food supply, but growth rate and body condition were not affected.

California↗
USGS2018

Effects of climate change on ecological disturbance in the Northern Rockies Region [Chapter 8]

This chapter describes the ecology of important disturbance regimes in the Forest Service, U.S. Department of Agriculture (USFS) Northern Region and the Greater Yellowstone Area, hereafter called the Northern Rockies region, and potential shifts in these regimes as a consequence of observed and projected climate change. The term disturbance regime describes the general temporal and spatial characteristics of a disturbance agent - insect, disease, fire, weather, even human activity - and the effects of that agent on the landscape (table 8.1). More specifically, a disturbance regime is the cumulative effect of multiple disturbance events over space and time (Keane 2013). Disturbances disrupt an ecosystem, community, or population structure and change elements of the biological environment, physical environment, or both (White and Pickett 1985). The resulting shifting mosaic of diverse ecological patterns and structures in turn affects future patterns of disturbance, in a reciprocal, linked relationship that shapes the fundamental character of landscapes and ecosystems. Disturbance creates and maintains biological diversity in the form of shifting, heterogeneous mosaics of diverse communities and habitats across a landscape (McKinney and Drake 1998), and biodiversity is generally highest when disturbance is neither too rare nor too frequent on the landscape (Grime 1973).

General Technical Report↗
USGS2019

Bottom trawl assessment of Lake Ontario prey fishes

Collaborative Lake Ontario bottom trawl surveys, led by the United States Geological Survey (USGS), provide science and management information for evaluating Fish Community Objectives including predator-prey balance and prey fish community diversity. In 2018, the New York State Department of Environmental Conservation (NYSDEC), Ontario Ministry of Natural Resources and Forestry (OMNR), and the (USGS) completed an April bottom trawl survey (n = 208 tows) and an October survey (n = 118 tows), at depths 6-228 m, and captured 384,651 fish from 31 species. Alewife were 80% of the total catch by number and round goby, deepwater sculpin, and rainbow smelt comprised 12, 4, and 3% of the catch, respectively. The adult alewife abundance index for U.S. waters decreased in 2018 relative to 2017, while the index in Canadian waters increased. While lake wide density increased, biomass indices for Age-2 alewife decreased. Alewife condition indices were below the 10-year average for both the April and October indices. The 2018 Age-1 alewife abundance index, which measures reproductive success the previous year, was the third lowest observed in U.S. waters over the past 22 years. The Canadian Age-1 index 2018 value was four-times larger than the U.S. value. Within-year differences between Canadian and U.S. alewife abundance indices, highlight the importance of assessing Lake Ontario fishes at a whole-lake scale. Abundance indices for rainbow smelt, threespine stickleback and emerald shiner were similar to 2017. New experimental trawl sites in embayment habitats generally captured more species, a higher proportion of native species, and higher densities relative to similar depth sites in the main lake and regions adjacent to embayments. Pelagic prey fish diversity continues to be low because a single species, alewife, dominates the catch. Deepwater sculpin and round goby were the most abundant demersal (bottom-oriented) prey fishes in 2018. Slimy sculpin and native nearshore demersal prey fishes, which were historically more abundant in trawl catches, are rare and restricted to specific habitats, since round goby proliferation. Despite declines in some species, demersal prey fish community diversity continues to increase as deepwater sculpin and round goby comprise more even portions of the community in contrast to when a single species, slimy sculpin, dominated the community. Five bloater were captured in the 2018 surveys which is the largest number captured in Lake Ontario since restoration stocking began in 2012.

Lake Ontario↗
USGS2007

Time scales and volumes of large ignimbrite-caldera eruptions in continental arc: Relation to assembly of subvolcanic batholiths

Volcanoes and upper-crustal plutons in diverse geologic settings tend to share common features of mineral and chemical compositions, emplacement age, and magmatic volume. Voluminous silicic ignimbrites associated with caldera sources, widespread components of Cordilleran arcs, have commonly been interpreted as broadly concurrent with assembly of upper-crustal batholiths. Tertiary ignimbrites in the westerns USA and elsewhere, with volumes to 1-5x10 3 km 3 , record multi-stage histories of magma accumulation, fractionation, and solidification in upper parts of large subvolcanic plutons that were sufficiently liquid to erupt. Indiviudal calderas, to 75 km across with 2-5 km subsidence, are direct evidence for shallow magma bodies comparable to the largest granitic plutons. Nested polycyclic calderas that erupted compositionally diverse tuffs, some with reposed intervals of 100 ka or less, document deep composite subsidence and rapid evolution in subvolcanic magmas. Most ignimbrite compositions are more evolved than associated plutons, requiring that subcaldera chambers retained voluminous residua from fractionation. Geophysical data that shows that low-density upper-crustal rocks, inferred to be plutons, are 10km or more thick beneath many calderas. Alternatively, some recent field and geochronologic studies have been interpreted as indicating that individual Mesozoic Cordilleran plutons grew and solidified incrementally in small batches during > 10 6- year intervals, without presence of voluminous eruptible magma ("large tank") at any stage during pluton growth and batholith assembly. Such growth in plutons in small increments would minimize close associations with large ignimbrite calderas and suggest that batholith growth is largely unrelated to surface volcanism. Linked to these interpretations are inferences that ignimbrite eruptions record ephemeral magma chambers that (1) grow rapidly due to exceptionally high magmatic power input to the upper crust, (2) evacuate nearly completely during ignimbrite eruption, and (3) leave little geologic record in the form of crystallized crustal plutons. How to reconcile these alternatives? Many large continental arcs record a broadly unified time-space-composition evolution of upper-crustal magmatic systems. Such volcanic fields especially those containing ignimbrite-caldera episodes, commonly contain compositionally diverse eruptive products erupted over multimillion-year intervals. A common pattern is initial eruptions of intermediate-composition lavas from central volcanoes, followed by eruption of one or more large-volume ignimbrites of more silicic composition; concurrent caldera subsidence is located centrally within the are of prior lava vents. Such progressions of surface volcanism can be interpreted as providing instantaneous sequential snapshots of changing magma-chamber process through time. In contrast, subvolcanic plutons exposed in eroded volcanic terranes represent time-integrated and partly homogenized end products, as successive magmatic pulses accumulated, fractionated, and consolidated in the upper crust. Such perspectives combine evidence for prolonged growth and incremental pluton assembly with presence of large-volume eruptible chambers during peak magmatic input.

Colorado↗
USGS2020

Bottom trawl assessment of Lake Ontario prey fishes, 2019

Multi-agency, collaborative Lake Ontario bottom trawl surveys provide information for decision making related to Fish Community Objectives including predator-prey balance and understanding prey fish community diversity. In 2019, bottom trawl surveys in April (n = 252 tows) and October (n = 160 tows) sampled main lake and embayments at depths from 5–226 m. Combined, the surveys captured 283,383 fish from 39 species. Alewife were 67% of the total catch by number while round goby, deepwater sculpin, and rainbow smelt comprised 13, 10, and 4% of the catch, respectively. In 2019, the lake-wide adult alewife biomass index declined from 2018 and age-1 biomass, a measure of reproductive success the previous year, was low. Year-class catch curve models identified years where estimates from surveys conducted only in U.S. waters were biased, potentially due to a greater portion of the alewife population inhabiting unsampled Canadian waters. Accounting for spatial survey bias, these model estimates indicated the 2019 adult alewife biomass was the lowest value in the 42-year time series. Models also identified the extent to which age-1 alewife biomass was historically underestimated, however lake-wide results from 2016-2019 appear less biased. If below-average year-class estimates from 2017 and 2018 are accurate, adult alewife biomass will continue to decline in 2020. Abundance indices for other pelagic prey fishes such as rainbow smelt, threespine stickleback, emerald shiner, and cisco were low and similar to 2018 values. Pelagic prey fish diversity is low because a single species, alewife, dominates the community. Deepwater sculpin and round goby were the most abundant demersal (bottom-oriented) prey fishes in 2019. Despite declines in slimy sculpin and other nearshore prey fishes, demersal prey fish community diversity has increased as deepwater sculpin and round goby comprise more even portions of the community. New experimental trawl sites in embayment habitats generally captured more species, a higher proportion of native species, and higher densities relative to main lake habitats. In 2019, a western tubenose goby (Proterorhinus semilunaris) was captured for the first time in the trawl surveys.

Lake Ontario↗
USGS2021

Alaska Landbird Conservation Plan

Alaska is a land of extremes. The diversity of its avifauna reflects the heterogeneity of its landscape, with more than 500 species of birds recorded in the state. Species inhabiting primarily terrestrial habitats, known collectively as landbirds, constitute the largest and most ecologically diverse component of the Alaska avifauna. Habitats used by landbirds range from temperate rainforests in southeastern Alaska to Arctic tundra across much of northern Alaska. Most of these landbird species are migratory, and four major global migration flyways converge on rich breeding areas in Alaska. Alaska has one endemic landbird species, the McKay’s Bunting, and is home to an impressive number of landbird populations for which it hosts a large proportion of the regional, continental, or global population. Thus, Alaska has a significant stewardship responsibility for these particular landbird species and subspecies. Habitats in Alaska remain largely pristine due to the region’s remote nature, vast size, and small human population. Alaska’s growing population and attendant economic development, however, present many challenges that could affect all wildlife, including landbirds. Threats in Alaska are often considered to be less significant than those occurring elsewhere, where habitats are being altered by more rapidly increasing anthropogenic pressures, but they carry far-reaching consequences nonetheless. Habitats and ecosystem dynamics are changing rapidly due to the magnitude of climate warming at high latitudes. As such, effective landbird conservation in Alaska requires a broad, landscape-scale approach. Conservation of landbirds over such an extensive and diverse landscape also demands that we integrate efforts in habitat management, population monitoring, research, education, and outreach at local, regional, continental, and international scales. Information on distribution and habitat requirements of landbirds should be incorporated into land-use planning decisions. Synthesizing information on distribution and population trends of landbirds is a critical, time-sensitive task. Such information should be provided in a form that is readily available to land managers and policy decision-makers. The primary objectives of this plan are to (1) describe the region and Alaska’s landbird avifauna; (2) identify species of concern, important habitats, and key information needs; (3) highlight major conservation issues and threats to landbirds; and (4) identify potential conservation actions. We first examine landbird conservation at the statewide level within broad perspectives (regional, continental, and global), then take a detailed look at the specific issues, information needs, and potential conservation actions within each Bird Conservation Region in Alaska.

Alaska↗
USGS1976

Epifauna at Jackson Point in Port Valdez, Alaska, December 1970 through September 1972

A biological sampling program at Jackson Point in Port Valdez, Alaska, was begun in December 1970. Sixteen artificial substrate samplers (8 multiplate and 8 rock-fllled baskets with net liners) were retrieved after 2 to 4 months' exposure. The most common groups in order of their abundance were Copepoda, Foraminifera, Nematoda, and Ostracoda during winter; Copepoda, Nematoda, Cirripedra, and Foraminifera, during spring; Pelecypoda, Amphipoda, Insecta, and Cirripedia during summer; and Pelecypoda, Copepoda, Insecta, and Nematoda during fall. The most abundant species collected during the study were the blue mussels ( Mytilus edulis ), copepods ( Harpacticus sp.), midges ( Clunio sp., Ghironomidae), and fairy shrimp (unidentified amphipods). During the summer and fall of 1972 the total number of epifaunal organisms was 22 times greater than during the same period in 1971, with Mytilus edulis comprising 88 percent of the community in 1972 (more than triple the percentage for 1971). The two sampler types collected approximately the same major groups of organisms; however, the multiplate samplers collected an average of 1.6 times more organisms than the basket samplers. The basket sampler, on the other hand, collected three more species per sample than did the multiplate samplers, resulting in species diversities 0.3 to 0.6 greater than those of the multiplate samplers. Diversity values were lower during 1972, except for the spring sample. Seasonal diversity varied from a low of 0.36 in the summer of 1972 to a high of 3.99 in the fall of 1971.

Alaska↗
USGS2022

Benefits of genetic data for the design of Brook Trout translocation efforts

With wild trout populations in decline, many conservation practitioners are evaluating the feasibility of incorporating reintroduction and genetic rescue into management frameworks. As interest in these conservation tools continues to grow, so too has the need for rigorous science to evaluate translocation success and improve the efficacy of future efforts. From this, it has become increasingly apparent that approaches which consider both demographics and genetics are most likely to result in successful translocations. In particular, while demographic data are often a central component of project designs, they are insufficient for diagnosing genetic threats such as low diversity, maladaptation, and introgression that characterize many wild trout populations. Consideration for these genetic characteristics is important for long-term project success and to reduce the unintended spread of domestic lineages across the landscape. Using a case study of reintroduction of Brook Trout Salvelinus fontinalis into a North Carolina stream, we show how a combined demographic and genetic approach can be used throughout all stages of project design. In particular, we highlight how genetic data were informative for identifying source populations that had the greatest potential to establish a population with the genetic diversity needed for future adaptation. We also discuss how genetic monitoring of the reintroduced population provided insights into reproductive success and genetic diversity that could be indicative of long-term population persistence. While monitoring is ongoing, this combined genetic and demographic approach provides a promising framework for helping meet reintroduction goals and provides more opportunities for adaptive management following translocation.

Conference Paper↗
USGS2022

Utilization of genetic data to inform native Brook Trout conservation in North Carolina

As North Carolina’s only native salmonid, Brook Trout Salvelinus fontinalis is a fish of considerable ecological and cultural significance in the state, but anthropogenic alterations to the landscape and introductions of nonnative salmonids have fragmented and reduced its native range. As a result, the North Carolina Wildlife Resources Commission (NCWRC) has enacted numerous efforts to help conserve the species. Annual demographic surveys of self-sustaining Brook Trout populations have been on-going since 1978, which have also included successful efforts to document previously unidentified populations. Beginning in earnest during the 1990s, allozyme testing was used to assess patterns of hatchery introgression, with over 480 collections genotyped at the creatine kinase locus. In 2010, the NCWRC began using microsatellite markers to conduct an extensive survey of Brook Trout genetic diversity and variation. To date, 541 Brook Trout collections representing 11,090 individuals have been genotyped at 12 microsatellite loci. These data have provided insights into evolutionary relationships among populations, spatial patterns of genetic diversity, and the extent of hatchery introgression within populations. Ultimately, increased understanding of genetic diversity and relatedness have been informative for determining that Brook Trout management in North Carolina is likely best enacted at the level of individual populations. Moreover, we have used these data to actively guide stream restoration and population reintroduction activities. Over the last 15 years, NCWRC and its partners have used genetic data to prioritize habitat enhancement activities and guide 17 Brook Trout population reintroduction projects. In the future, we plan to continue expanding the microsatellite genetic baseline while also exploring the utility of phylogenomic analyses to inform Brook Trout conservation activities. Genetic and genomic approaches have great potential to improve the efficacy of conservation actions for Brook Trout in North Carolina and throughout its native range.

North Carolina↗
USGS2023

Simulation of genetic change under four removal strategies for a wild horse population

Small and/or artificially reduced populations can suffer genetic erosion with long-term consequences to population fitness and persistence. However, managers must periodically remove free-roaming horses from the landscape to reduce the risk of habitat degradation. We developed an individual-based population simulation model to evaluate the expected change in genetic diversity after 100 years under each of four removal strategies for the wild horse population in the Pryor Mountain management area with removals occurring every 5 years, and assuming that no additional horses are introduced to the herd. We found that long generations and high survival rates of this wild horse population guard against rapid loss of genetic diversity for all scenarios in general. However, scenarios that included a removal strategy prioritizing individuals for removal based on relatedness initially increased mean genetic diversity that was subsequently maintained at a higher level than strategies that randomly selected individuals for removal.

Report↗
USGS2025

Evidence for offset of Cretaceous plutons by the Tintina fault in eastern Alaska: Implications for regional metallogeny

Cretaceous magmatism in eastern interior Alaska is voluminous, but temporally and spatially diverse – suggestive of varying sources and drivers. More than 150 new U-Pb zircon and more than 500 geochemical analyses of Cretaceous plutonic units allow for the grouping of distinct plutonic suites. Magmatism was continuous from 120-66 Ma but can be grouped into temporally distinct pulses from ca. 115-100 Ma, 100-90 Ma, and 75-66 Ma. Geochemical diversity occurs during each pulse, further distinguishing multiple suites. Diverse metallogenic epochs are strongly correlated to pluton chemistry. Mineralization is largely absent prior to 108 Ma. From 108-100 Ma, plutonism is coeval with sparse, but notable Au-quartz veins with variable Bi, As, W, and Mo. From 100-90 Ma, intrusion-related mineralization zones from Au-Cu(-Bi) and U-Th in the northwest to central Au- Bi-As-Te(-W), and Mo-W to the southeast. Porphyry style Cu-Mo(-Au) occurrences occur with the latest Cretaceous plutons emplaced from 75-66 Ma . Restoration of ~450 km of dextral movement on the Tintina fault and comparison of metallogenic and geochemical characteristics of Alaska plutons suggest 100-90 Ma plutons may be the continuation of the metallogenically significant Tombstone, Mayo, and Tungsten suites from the Yukon.

Alaska↗
USGS2023

Attributes of Upper Mississippi River System contiguous forest areas

Floodplain forests are important features of river systems as they create habitat for a variety of wildlife species as well as influence water quality by sequestering nutrients. The ecological conditions found within forested areas can vary greatly from place to place, contributing to spatial variability in species diversity, animal use of the floodplain, and other ecological functions. For this reason, it is important for managers and researchers to identify and map existing forest conditions for use in restoration practices or research studies. A number of forest attributes have been identified as useful in predicting the local ecological conditions found within forested areas. For example, attributes related to the size, shape and configuration of forest patches have been linked to susceptibility to invasion by exotic species, animal and plant dispersal patterns, population distributions, and species diversity (Zuidema and others, 1996; Laurance and others, 2001; Weathers and others, 2001; Lindenmayer and Franklin 2002; Harper and others, 2005; Ramaharitra 2006). In floodplain forests, patterns of inundation have been shown to influence local soil conditions as well as plant species composition and diversity (De Jager and others, 2012). Knowing the land-use history of forest areas has also been shown to be important in understanding present day ecological conditions of forested areas (Turner and others, 2004). To support floodplain forest research and management actions on the Upper Mississippi River System (UMRS), we identified contiguous forested areas (i.e., areas of forest cover that were separated from each other by other land or water cover types) in the floodplain and calculated a wide range of attributes that define basic ecosystem conditions within such forested areas. The data allows users to query on a set of attributes (e.g., size, shape, inundation characteristics, etc.) to visualize the distribution of various ecological conditions. In addition, the data allows for future data analyses of relationships among different ecological conditions and other data, such as animal and plant population distributions.

Upper Mississippi River system↗
USGS2026

Genetic analysis of Harbison’s Dun Skipper to inform population management and restoration on conserved lands in San Diego County

This report details the development and analysis of single nucleotide polymorphic loci to understand population genetic structure and diversity among local populations of the Harbison’s dun skipper, Euphyes vestris harbisoni , primarily in San Diego County, California, USA. We developed a set of 2984 SNPs. Local populations were clustered into two to three regional genetic clusters throughout the San Diego County study area: a southeast cluster, an admixed northeast cluster, and a cluster comprised of the two local populations sampled west of Interstate 15 in Lake Hodges and Elfin Forest. Increasing genetic isolation with geographic distance was significant among local populations. While effective population size estimates calculated for the 2016 cohorts in the Southeast and Lake Hodges clusters were both high (point estimates above 500), individual heterozygosity appeared to decline in both clusters over time, and notably so in the Lake Hodges cluster after 2016, suggesting that this cluster may have lost genetic diversity over time. The Southeast cluster appears to have the highest observed heterozygosity across all surveyed areas, but sample sizes in the Northeast cluster were low which may affect these estimates. Future collection efforts may benefit from additional sampling in the Northeast cluster to improve representation. The management plan for Harbison’s dun skipper encourages restoration and re-establishment efforts in unoccupied or recently extirpated sites, particularly in the central portion of the range. Re-establishment efforts could target individuals from large and annually stable local populations in the Southeast portion of the range for transplant, as these populations were also the most genetically diverse.

California↗
USGS2004

Waterfowl migration on Klamath Basin National Wildlife Refuges 1953-2001

The Klamath Basin National Wildlife Refuge (NWR) complex, located in northeastern California and southern Oregon, is situated on a major Pacific Flyway migration corridor connecting waterfowl breeding grounds in the north with major wintering grounds in California and Mexico. The complex comprises five waterfowl refuges including Lower Klamath NWR, Tule Lake NWR, Upper Klamath NWR, Klamath Marsh NWR, and Clear Lake NWR, and one bald eagle refuge, Bear Valley NWR. Lower Klamath and Tule Lake NWRs are the largest refuges in the complex; historically, they supported some of the greatest autumn and spring concentrations of migrating waterfowl in North America. Starting in 1953, standardized waterfowl surveys from small aircraft have been conducted in autumn through spring. This report summarizes waterfowl migration activity (i.e., abundance, species composition, distribution on refuges, and chronology) over four time periods—the long-term (1953-2001), early (1953-76), recent (1977-2001), and the most recent (1998-2001)—to describe changing patterns of migration on Klamath Basin refuges from autumn 1953 to spring 2001. Over the long term, waterfowl abundance (birds per day) on the refuge complex averaged about 1.0 million in autumn and about 360,000 in spring. A record peak count of 5.8 million waterfowl was recorded September 24-25, 1958. Average abundance of autumn staging waterfowl for the refuge complex, after reaching record levels in the 1950s and early 1960s, began a decline that lasted until the 1980s. A gradual recovery occurred during the 1990s, but autumn abundance has not recovered to pre-1970 levels. In contrast to autumn, average spring abundance was generally lower in the early decades but has gradually increased through the 1990s, particularly on Lower Klamath NWR. Dabbling ducks represented an average of 68% of all waterfowl in autumn and 55% in spring for the long term. Northern pintail ( Anas acuta ) was dominant, representing 62% of all dabblers in autumn and 51% in spring. A significant decline in pintail abundance starting in the late 1950s altered waterfowl composition on Klamath Basin refuges. As pintail declined, other species such as mallard ( Anas platyrhynchos ) and green-winged teal ( Anas crecca ) increased in abundance. Although Arctic nesting geese, including white-fronted ( Anser albifrons ), cackling Canada ( Branta canadensis minima ), white geese (lesser snow [ Chen caerulescens caerulescens ], and Ross’s [ Chen rossii ]) have become less prominent in recent decades, they reached an historically high abundance during autumn in the 1960s and 1970s, particularly on Tule Lake NWR. Tule Lake NWR supported the highest average autumn waterfowl populations until surpassed by Lower Klamath NWR around 1980. During the recent period (1977-2001), Lower Klamath NWR accounted for 60% of all waterfowl using the refuge complex in autumn and 61% in spring. Habitat diversity and wetland productivity contributed to its greater waterfowl abundance. Tule Lake NWR supported the most geese over the long term, 79% in autumn and 66% in spring; however, total waterfowl abundance on this refuge in autumn has been in decline, likely because of reduced diversity and productivity of sumps in the refuge. Upper Klamath, Klamath Marsh, and Clear Lake NWRs accounted for less than 8% of total waterfowl use in autumn and spring but provided diverse habitats for migrants. Waterfowl use-days on Klamath Basin refuges typically peaked in mid-autumn, decreased as migrants passed through the basin, and then reached a lesser peak during spring passage. Waterfowl abundance reached a pronounced peak in autumn during the early period (1953-76), but spring peak buildup was much less pronounced. For the recent period the autumn peak was more subdued. Waterfowl abundance, species composition, and distribution on Klamath Basin refuges have fluctuated over the decades and have been influenced by events such as productivity on breeding grounds and habitat conditions on wintering grounds that cause shifts in migration patterns. A major challenge for the future appears to be the availability of adequate water for wetland management on Klamath Basin refuges.

California, Oregon↗
USGS2021

Extrinsically reinforced hybrid speciation within Holarctic ermine (Mustela spp.) produces an insular endemic

Aim Refugial isolation during glaciation is an established driver of speciation; however, the opposing role of interglacial population expansion, secondary contact, and gene flow on the diversification process remains less understood. The consequences of glacial cycling on diversity are complex and especially so for archipelago species, which experience dramatic fluctuations in connectivity in response to both lower sea levels during glacial events and increased fragmentation during glacial recession. We test whether extended refugial isolation has led to the divergence of genetically and morphologically distinct species within Holarctic ermine ( Mustela erminea ), a small cosmopolitan carnivore species that harbours 34 extant subspecies, 14 of which are insular endemics. Location Holarctic. Methods We use genetic sequences (complete mitochondrial genomes, four nuclear genes) from >100 ermine (stoats) and geometric morphometric data for >200 individuals (27 of the 34 extant subspecies) from across their Holarctic range to provide an integrative perspective on diversification and endemism across this complex landscape. Multiple species delimitation methods ( iBPP , bPTP ) assessed congruence between morphometric and genetic data. Results Our results support the recognition of at least three species within the M. erminea complex, coincident with three of four genetic clades, tied to diversification in separate glacial refugia. We found substantial geographic variation within each species, with geometric morphometric results largely consistent with historical infraspecific taxonomy. Main conclusions Phylogeographic structure mirrors patterns of diversification in other Holarctic species, with a major Nearctic‐Palearctic split, but with greater intraspecific morphological diversity. Recognition of insular endemic species M. haidarum is consistent with a deep history of refugial persistence and highlights the urgency of mindful management of island populations along North America's North Pacific Coast. Significant environmental modification (e.g. industrial‐scale logging, mining) has been proposed for a number of these islands, which may elevate the risk of extinction of insular palaeoendemics.

Diversity and Distributions↗
USGS2022

Increased landscape disturbance and streamflow variability threaten fish biodiversity in the Red River catchment, USA

Aim Stream fish distributions are hypothesized to be strongly associated with landscape characteristics at multiple scales. Variation in flow regimes and intensity of landscape disturbance are associated with stream fish distributions; however, relationships are poorly understood in many high-diversity regions. Our objective was to identify occurrence relationships between fish distributions and streamflow and landscape characteristics in the south-central United States. Location Our study area was the central Red River catchment in Oklahoma, Texas and Arkansas, USA. Methods We used existing fish surveys to model the occurrence of a diverse, warmwater assemblage among hydraulic response units (HRUs). We used multispecies occupancy modelling to identify variation in occurrence probability among 111 stream fishes in relation to landscape disturbance and flow regime characteristics. Results We found occurrence relationships with landscape disturbance and 11 metrics comprising all flow-regime components. The relationships varied within both major species groups and some genera. Frequency and duration were the most common metrics underlying flow regime relationships. More common stream fishes tended to be positively associated with higher levels of landscape disturbance and flow regime metrics representing variability; conversely, narrow-ranged fishes tended to be negatively associated. Occurrence relationships with flow metrics representing high-flow events were predominately negative. As expected, many species were strongly associated with ecoregion with landscape disturbance and flow relationships held constant. Main conclusions Our study informs land use and water management decisions and stream fish conservation at multiple spatial scales. Collectively, the findings suggest potential homogenization of the Red River fish assemblage with increased landscape disturbance and streamflow variability. A reduction in landscape disturbance and maintenance of natural flow patterns at coarser scales may benefit endemic and narrow-ranged fishes. Our findings also help guide finer-scale land use and water management decisions by identifying stream network areas with a high occurrence probability of less tolerant fishes.

Arkansas, Oklahoma, Texas↗