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At least 217 records · Page 12Linked to original sources
USGS2015

Comparing spatial capture–recapture modeling and nest count methods to estimate orangutan densities in the Wehea Forest, East Kalimantan, Indonesia

Accurate information on the density and abundance of animal populations is essential for understanding species' ecology and for conservation planning, but is difficult to obtain. The endangered orangutan ( Pongo spp.) is an example; due to its elusive behavior and low densities, researchers have relied on methods that convert nest counts to orangutan densities and require substantial effort for reliable results. Camera trapping and spatial capture–recapture (SCR) models could provide an alternative but have not been used for primates. We compared density estimates calculated using the two methods for orangutans in the Wehea Forest, East Kalimantan, Indonesia. Camera trapping/SCR modeling produced a density estimate of 0.16 ± 0.09–0.29 indiv/km 2 , and nest counts produced a density estimate of 1.05 ± 0.18–6.01 indiv/km 2 . The large confidence interval of the nest count estimate is probably due to high variance in nest encounter rates, indicating the need for larger sample size and the substantial effort required to produce reliable results using this method. The SCR estimate produced a very low density estimate and had a narrower but still fairly wide confidence interval. This was likely due to unmodeled heterogeneity and small sample size, specifically a low number of individual captures and recaptures. We propose methodological fixes that could address these issues and improve precision. A comparison of the overall costs and benefits of the two methods suggests that camera trapping/SCR modeling can potentially be a useful tool for assessing the densities of orangutans and other elusive primates, and warrant further investigation to determine broad applicability and methodological adjustments needed.

East Kalimantan↗
USGS2009

Rebuttal of "Polar bear population forecasts: a public-policy forecasting audit"

Observed declines in the Arctic sea ice have resulted in a variety of negative effects on polar bears ( Ursus maritimus ). Projections for additional future declines in sea ice resulted in a proposal to list polar bears as a threatened species under the United States Endangered Species Act. To provide information for the Department of the Interior's listing-decision process, the US Geological Survey (USGS) produced a series of nine research reports evaluating the present and future status of polar bears throughout their range. In response, Armstrong et al. [Armstrong, J. S., K. C. Green, W. Soon. 2008. Polar bear population forecasts: A public-policy forecasting audit. Interfaces 38 (5) 382–405], which we will refer to as AGS, performed an audit of two of these nine reports. AGS claimed that the general circulation models upon which the USGS reports relied were not valid forecasting tools, that USGS researchers were not objective or lacked independence from policy decisions, that they did not utilize all available information in constructing their forecasts, and that they violated numerous principles of forecasting espoused by AGS. AGS (p. 382) concluded that the two USGS reports were "unscientific and inconsequential to decision makers." We evaluate the AGS audit and show how AGS are mistaken or misleading on every claim. We provide evidence that general circulation models are useful in forecasting future climate conditions and that corporate and government leaders are relying on these models to do so. We clarify the strict independence of the USGS from the listing decision. We show that the allegations of failure to follow the principles of forecasting espoused by AGS are either incorrect or are based on misconceptions about the Arctic environment, polar bear biology, or statistical and mathematical methods. We conclude by showing that the AGS principles of forecasting are too ambiguous and subjective to be used as a reliable basis for auditing scientific investigations. In summary, we show that the AGS audit offers no valid criticism of the USGS conclusion that global warming poses a serious threat to the future welfare of polar bears and that it only serves to distract from reasoned public-policy debate.

Interfaces↗
USGS2021

Genetic variation in sea otters (Enhydra lutris) from the North Pacific with relevance to the threatened Southwest Alaska Distinct Population Segment

For the sea otter ( Enhydra lutris ), genetic population structure is an area of research that has not received significant attention, especially in Southwest Alaska where that distinct population segment has been listed as threatened since 2005 pursuant to the U.S. Endangered Species Act. In this study, 501 samples from 14 locations from Prince William Sound, Alaska to the Commander Islands in Russia were analyzed for variation at 13 microsatellite loci. Our results indicate a high degree of genetic divergence among the 14 locations ( F ST = 0.120) with gene flow conforming to the isolation by distance (IBD) model ( r 2 = 0.491, p < .05). The 14 sampling locations formed six geographic associations in clustering and ordination analyses that likely correspond to remnant population lineages: (1) Southcentral Alaska, (2) Kodiak and North Alaska Peninsula, (3) South Alaska Peninsula and Bristol Bay, (4) Eastern Aleutian, (5) Western Aleutian, and (6) the Commander Islands. Except for South Alaska Peninsula and Bristol Bay, these clusters closely agree with previously defined stock and management unit boundaries. Our results reveal significant genetic population structure and are generally congruent with current management strategies for the threatened Southwest Alaska distinct population segment.

Alaska↗
USGS2006

Ecology and habitat of breeding Northern Goshawks in the inland Pacific Northwest: A summary of research in the 1990s

During the 1990s, we conducted research on the distribution, productivity, and habitat relationships of Northern Goshawks (Accipiter gentilis) in eastern Oregon and Washington. Our research was initiated primarily in response to concerns raised about the status of Northern Goshawks in the western US, and coincided with early attempts to list the species as threatened or endangered under the Endangered Species Act and the publication of management guidelines for goshawks in the southwestern US. To develop baseline information on the status, distribution, and habitat relationships of goshawks in eastside forests (i.e., east of the Cascade Mountain Range) in the Pacific Northwest, we established study areas on three national forests in eastern Oregon in 1992, adding a fourth study area in central Washington in 1994. We focused on the breeding season and nesting habitat because of its primary importance to goshawk ecology and the logistical feasibility of finding nests. Density of breeding pairs ranged from 0.03-0.09/100 ha, and annual productivity ranged from 0.3-2.2 young fledged/nest. Goshawks selected forest stands with trees of larger diameter and greater canopy closure for nesting than available in the landscape. Occasionally nests could be found in large trees in open-canopied stands. As distance increased from the nest site, forest type and structure became more heterogeneous and the prevalence of older-seral-stage forest declined. Dry or wet openings were present in most territories, often within close proximity to nest stands. Goshawks ate a variety of mammalian and avian prey. Mammal species made up a larger portion of prey biomass on two of the national forests, but avian species appeared to be more prevalent in the diet of goshawks in the most northern study area. We recommend that the existing management guidelines for goshawks in the Southwest form a basis for management in the inland Pacific Northwest, particularly with regard to nested spatial concepts, emphasis on management of prey, and the use of silviculture to promote the development and replacement of old growth or late-seral-stage forest. Our research and management recommendations can be used in concert with the Southwestern management guidelines to establish a mix of vegetation structural stages to support goshawk populations, their prey, and other forest wildlife species specifically for the inland Pacific Northwest.

Studies in Avian Biology↗
USGS2020

Mapping habitat suitability at range-wide scales: Spatially explicit distribution models to inform conservation and research for marsh birds

Habitat Loss is a primary cause of species decline, and predicting the distribution of quality habitats across broad scales is needed for conservation of rare species. Secretive marsh birds are a group of emergent-wetland specialists that include multiple threatened and endangered species whose populations have been impacted by wetland loss and modification. Habitat suitability for marsh birds is poorly mapped, and predictions of habitat quality over broad scales are primarily generated via expert judgment. We developed data-driven models to predict fine-resolution habitat quality for 13 marsh bird species across their ranges within the U.S. We demonstrate how these models are useful for conservation by quantifying range contraction, assessing the usefulness of existing protected areas, and assessing the vulnerability of habitats to global change for rare species. These tools provide a quantitative foundation for broad-scale conservation, research, and monitoring efforts, and a starting point for adaptive conservation of marsh bird breeding habitat over broad spatial extents.

Conservation Science and Practice↗
USGS2003

Fire and amphibians in North America

Information on amphibian responses to fire and fuel reduction practices is critically needed due to potential declines of species and the prevalence of new, more intensive fire management practices in North American forests. The goals of this review are to summarize the known and potential effects of fire and fuels management on amphibians and their aquatic habitats, and to identify information gaps to help direct future scientific research. Amphibians as a group are taxonomically and ecologically diverse; in turn, responses to fire and associated habitat alteration are expected to vary widely among species and among geographic regions. Available data suggest that amphibian responses to fire are spatially and temporally variable and incompletely understood. Much of the limited research has addressed short-term (1–3 years) effects of prescribed fire on terrestrial life stages of amphibians in the southeastern United States. Information on the long-term negative effects of fire on amphibians and the importance of fire for maintaining amphibian communities is sparse for the majority of taxa in North America. Given the size and severity of recent wildland fires and the national effort to reduce fuels on federal lands, future studies are needed to examine the effects of these landscape disturbances on amphibians. We encourage studies to address population-level responses of amphibians to fire by examining how different life stages are affected by changes in aquatic, riparian, and upland habitats. Research designs need to be credible and provide information that is relevant for fire managers and those responsible for assessing the potential effects of various fuel reduction alternatives on rare, sensitive, and endangered amphibian species.

Forest Ecology and Management↗
USGS2024

Range-wide genetic analysis of an endangered bumble bee (Bombus affinis, Hymenoptera: Apidae) reveals population structure, isolation by distance, and low colony abundance

Declines in bumble bee species range and abundances are documented across multiple continents and have prompted the need for research to aid species recovery and conservation. The rusty patched bumble bee ( Bombus affinis ) is the first federally listed bumble bee species in North America. We conducted a range-wide population genetics study of B. affinis from across all extant conservation units to inform conservation efforts. To understand the species’ vulnerability and help establish recovery targets, we examined population structure, patterns of genetic diversity, and population differentiation. Additionally, we conducted a site-level analysis of colony abundance to inform prioritizing areas for conservation, translocation, and other recovery actions. We find substantial evidence of population structuring along an east-to-west gradient. Putative populations show evidence of isolation by distance, high inbreeding coefficients, and a range-wide male diploidy rate of ~15%. Our results suggest the Appalachians represent a genetically distinct cluster with high levels of private alleles and substantial differentiation from the rest of the extant range. Site-level analyses suggest low colony abundance estimates for B. affinis compared to similar datasets of stable, co-occurring species. These results lend genetic support to trends from observational studies, suggesting that B. affinis has undergone a recent decline and exhibit substantial spatial structure. The low colony abundances observed here suggest caution in overinterpreting the stability of populations even where B. affinis is reliably detected interannually. These results help delineate informed management units, provide context for the potential risks of translocation programs, and help set clear recovery targets for this and other threatened bumble bee species.

Iowa, Illinois, Indiana, Kentucky, Michigan, Minne↗
USGS2006

Monitoring changes in the Platte River riparian corridor with serial LiDAR surveys

The Platte River in central Nebraska is a wide, sand-bedded river that provides habitat for migratory water birds along the North American flyway. The central Platte River functions as critical habitat for the endangered whooping crane (Grus americana) and also is an important habitat for the endangered least tern (Sterna antillarum) and the threatened piping plover (Charadrius melodus). Upstream water-resource development over the last century has decreased the water and sediment supplied to the central Platte River. This has resulted in vegetation encroachment and narrowing of Platte River channels. The National Academy of Sciences' National Research Council, in a recent review of these critical habitat designations, concluded that the current morphology of Platte River channels is limiting the recovery of the endangered and threatened avian species. Habitat-enhancement efforts along the Platte River currently (2006) are focused on the clearing of vegetation from in-channel and riparian areas, whereas future plans propose the release of water from upstream dams as a means to prevent vegetation from encroaching on the active river channel. For this reason, monitoring the physical response of the river channel to these management treatments is an important component of a proposed habitat recovery program. Understanding the effects of management strategies on Platte River riparian habitat also is a key objective of the U.S. Geological Survey's Platte River Priority Ecosystem Program (http://mcmcweb.er.usgs.gov/platte/). This fact sheet describes applications of LiDAR to monitor changes in the Platte River riparian corridor.

Fact Sheet↗
USGS2017

Early action to address an emerging wildlife disease

A deadly fungal pathogen, Batrachochytrium salamandrivorans ( Bsal ) that affects amphibian skin was discovered during a die-off of European fire salamanders ( Salamandra salamandra ) in 2014. This pathogen has the potential to worsen already severe worldwide amphibian declines. Bsal is a close relative to another fungal disease known as Batrachochytrium dendrobatidis ( Bd ). Many scientists consider Bd to be the greatest threat to amphibian biodiversity of any disease because it affects a large number of species and has the unusual ability to drive species and populations to extinction. Although not yet detected in the United States, the emergence of Bsal could threaten the salamander population, which is the most diverse in the world. The spread of Bsal likely will lead to more State and federally listed threatened or endangered amphibian species, and associated economic effects. Because of the concern expressed by resource management agencies, the U.S. Geological Survey (USGS) has made Bsal and similar pathogens a priority for research.

Fact Sheet↗
USGS1996

Comparative demography of sea otter populations

Population trends are poorly documented and demographic information is typically lacking for many carnivorous mammals. The sea otter ( Enhydru lutris ) has a well known history of decline and recovery, and while many other species have declined as precipitously, few have recovered so spectacularly. Generally speaking, northern populations (remnants within the range of E. l. lutris and E. l. kenyoni ) have recovered at high rates while recovery of the southern sea olter ( E. I. nereis ), which is listed as legally threatened under the Endangered Species Act (ESA), has progressed more slowly. Our purpose is to contrast trends in abundance and demographic patterns between Southern California and northern (Washington, British Columbia, Alaska, and Asia) sea otter populations. Specifically, we provide (1) a brief review of the main findings to date: (2) a summary of ongoing and planned studies; and (3) recommendations for future research. A more detailed account of these and other issues concerning the conservation and management of sea otters is provided in the U.S. Fish and Wildlife Service's Recovery Plan for the Califomia Sea Otter (U.S. Fish and Wildlife Service 1996).

Endangered Species UPDATE↗
USGS2017

Microsatellite marker development from next-generation sequencing in the New England cottontail (Sylvilagus transitionalis) and cross-amplification in the eastern cottontail (S. floridanus)

Objective The New England cottontail ( Sylvilagus transitionalis ) is a species of high conservation priority in the Northeastern United States, and was a candidate for federal listing under the Endangered Species Act until a recent decision determined that conservation actions were sufficient to preclude listing. The aim of this study was to develop a suite of microsatellite loci to guide future research efforts such as the analysis of population genetic structure, genetic variation, dispersal, and genetic mark-recapture population estimation. Results Thirty-five microsatellite markers containing tri- and tetranucleotide sequences were developed from shotgun genomic sequencing of tissue from S. transitionalis , S. obscurus , and S. floridanus . These loci were screened in n = 33 wild S. transitionalis sampled from a population in eastern Massachusetts, USA. Thirty-two of the 35 loci were polymorphic with 2–6 alleles, and observed heterozygosities of 0.06–0.82. All loci conformed to Hardy–Weinberg Equilibrium proportions and there was no evidence of linkage disequilibrium or null alleles. Primers for 33 of the 35 loci amplified DNA extracted from n = 6 eastern cottontail ( S. floridanus ) samples, of which nine revealed putative species-diagnostic alleles. These loci will provide a useful tool for conservation genetics investigations of S. transitionalis and a potential diagnostic species assay for differentiating sympatric eastern and New England cottontails.

Massachusetts↗
USGS2014

BatTool: an R package with GUI for assessing the effect of White-nose syndrome and other take events on Myotis spp. of bats

Background: Myotis species of bats such as the Indiana Bat and Little Brown Bat are facing population declines because of White-nose syndrome (WNS). These species also face threats from anthropogenic activities such as wind energy development. Population models may be used to provide insights into threats facing these species. We developed a population model, BatTool, as an R package to help decision makers and natural resource managers examine factors influencing the dynamics of these species. The R package includes two components: 1) a deterministic and stochastic model that are accessible from the command line and 2) a graphical user interface (GUI). Results: BatTool is an R package allowing natural resource managers and decision makers to understand Myotis spp. population dynamics. Through the use of a GUI, the model allows users to understand how WNS and other take events may affect the population. The results are saved both graphically and as data files. Additionally, R-savvy users may access the population functions through the command line and reuse the code as part of future research. This R package could also be used as part of a population dynamics or wildlife management course. Conclusions: BatTool provides access to a Myotis spp. population model. This tool can help natural resource managers and decision makers with the Endangered Species Act deliberations for these species and with issuing take permits as part of regulatory decision making. The tool is available online as part of this publication.

Source Code for Biology and Medicine↗
USGS2010

Deterring off-trail hiking in protected natural areas: Evaluating options with surveys and unobtrusive observation: Final report

This report presents the results of research conducted on the 96-acre Bear Island along the Billy Goat Trail, Section A (BGT) that evaluated visitor motivations for off-trail hiking and the efficacy of four treatments designed to reduce this activity. This research was prompted by concerns about the impact of an extensive informal (visitor-created) trail network on Bear Island, because it provides habitat for more than 50 species of rare, threatened or endangered plant and animal species.

Final Management Report↗
USGS2013

A landscape-based assessment of climate change vulnerability for all native Hawaiian plants

In Hawaiʽi and elsewhere, research efforts have focused on two main approaches to determine the potential impacts of climate change on individual species: estimating species vulnerabilities and projecting responses of species to expected changes. We integrated these approaches by defining vulnerability as the inability of species to exhibit any of the responses necessary for persistence under climate change (i.e., tolerate projected changes, endure in microrefugia, or migrate to new climate-compatible areas, but excluding evolutionary adaptation). To operationalize this response-based definition of species vulnerability within a landscape-based analysis, we used current and future climate envelopes for each species to define zones across the landscape: the toleration zone; the microrefugia zone; and the migration zone. Using these response zones we calculated a diverse set of factors related to habitat area, quality, and distribution for each species, including the amount of habitat protection and fragmentation and areas projected to be lost to sea-level rise. We then calculated the probabilities of each species exhibiting these responses using a Bayesian network model and determined the overall climate change vulnerability of each species by using a vulnerability index. As a first iteration of a response-based species vulnerability assessment (VA), our landscape-based analysis effectively integrates species-distribution models into a Bayesian network-based VA that can be updated with improved models and data for more refined analyses in the future. Our results show that the species most vulnerable to climate change also tend to be species of conservation concern due to non-climatic threats (e.g., competition and predation from invasive species, land-use change). Also, many of Hawaiʽi’s taxa that are most vulnerable to climate change share characteristics with species that in the past were found to be at risk of extinction due to non-climatic threats (e.g., archipelago endemism, single-island endemism). Of particular concern are the numerous species that have no compatible-climate areas remaining by the year 2100. Species primarily associated with dry forests have higher vulnerability scores than species from any other habitat type. When examined at taxonomic levels above species, low vulnerabilities are concentrated in families and genera of generalists (e.g., ferns or sedges) and typically associated with mid-elevation wet habitats. Our results replicate findings from other regions that link higher species vulnerability with decreasing range size. This species VA is possibly the largest in scope ever conducted in the United States with over 1000 species considered, 319 of which are listed as endangered or threatened under the U.S. Endangered Species Act, filling a critical knowledge gap for resource managers in the region. The information in this assessment can help prioritize species for special conservation actions, guide the management of conservation areas, inform the selection of research and monitoring priorities, and support adaptive management planning and implementation.

Hawai'i↗
USGS1996

The relevance of the Mediterranean Region to colonial waterbird conservation

The Mediterranean Sea is the largest partially enclosed sea in the world and provides habitat to more than 100 species of waterbirds from the Palearctic-North African-Middle Eastern regions. Even though the Mediterranean suffers from pollution, has little tidal influence, and is oligotrophic, more than half of the western Palearctic populations of numerous waterfowl species winter in the region. Thirty-three species of colonial waterbirds breed along the 46,000 km Mediterranean coastline with nine species considered threatened or endangered, mostly because of wetland loss and degradation. The long history of human activity and scientific investigations in the region has taught some valuable lessons. In the area of colonial waterbird biology and conservation, we have learned important lessons about the value of long-term monitoring and research on selected populations. From marking studies of Greater Flamingos (Phoenicopterus ruber roseus) and Little Egrets (Egretta garzetta) results have been used to derive useful information about metapopulation dynamics. Involvement of both African and European biologists allowed year-round Studies of these species that yielded valuable spin-offs for training in avian and wetland conservation. We have also learned the value of man-made wetlands as feeding and nesting sites for some colonial waterbirds. Careful evaluations of the habitat quality of different types of wetlands are required, as in contaminant levels such as lead shot and pesticides. Wetland conservationists have also learned from some instructive mistakes. Dam construction and agricultural incentive programs sponsored by the European Community, the World Bank, and others from the past have largely ignored impacts on wetlands and wildlife. In some areas, economic ventures such as aquaculture operations and salt mining have not involved waterbird habitat needs in their planning. Research and conservation needs include: (1) establishing regional monitoring programs and data banks for seabirds, wading birds, ducks, and geese; (2) implementing a wetland inventory for many Countries with little quantitative data on wetlands; (3) improving habitat quality assessments; (4) improving relationships with industry, the private citizenry, and government officials to further an appreciation for the value of wetlands and waterbirds; (5) enhancing training efforts, especially in underdeveloped Countries; (6) evaluating the effects of hunting and other disturbances to nesting and feeding waterbirds in different regions; (7) setting up 'sister-reserve' (twinned) sites in Europe and Africa to foster international linkages and training; and (8) fostering local-regional conservation programs to preserve reed beds, wet woodlots, and other key habitats.

Book chapter↗
USGS2016

North American sturgeon otolith morphology

Accurate expedient species identification of deceased sturgeon (Acipenseridae) when external physical characteristic analysis is inconclusive has become a high priority due to the endangered or threatened status of sturgeon species around the world. Examination of otoliths has provided useful information to aid in population management, age and size-class analysis, understanding predator&ndash;prey interactions, and archeological research in other fish species. The relationship between otolith characteristics and sturgeon species has remained unknown. Therefore, we analyzed the shape of otoliths from the eight species of sturgeon found in North America to test the utility of otolith characteristic morphology in species identification. There were distinct differences in the size and shape of the otoliths between species of sturgeon with little shape variation among individuals of the same species. The relationship between otolith length axes was linear, and most of the variability was explained by a Log (axis + 1) transformation of the x and y axes (r 2 = 0.8983) using the equation y = 0.73x + 0.0612. Images of otoliths from all eight North American species are presented to assist in the identification process.

Copeia↗
USGS2011

Big Spring spinedace and associated fish populations and habitat conditions in Condor Canyon, Meadow Valley Wash, Nevada

Executive Summary: This project was designed to document habitat conditions and populations of native and non-native fish within the 8-kilometer Condor Canyon section of Meadow Valley Wash, Nevada, with an emphasis on Big Spring spinedace (Lepidomeda mollispinis pratensis). Other native fish present were speckled dace (Rhinichthys osculus) and desert sucker (Catostomus clarki). Big Spring spinedace were known to exist only within this drainage and were known to have been extirpated from a portion of their former habitat located downstream of Condor Canyon. Because of this extirpation and the limited distribution of Big Spring spinedace, the U.S. Fish and Wildlife Service listed this species as threatened under the Endangered Species Act in 1985. Prior to our effort, little was known about Big Spring spinedace populations or life histories and habitat associations. In 2008, personnel from the U.S. Geological Survey's Columbia River Research Laboratory began surveys of Meadow Valley Wash in Condor Canyon. Habitat surveys characterized numerous variables within 13 reaches, thermologgers were deployed at 9 locations to record water temperatures, and fish populations were surveyed at 22 individual sites. Additionally, fish were tagged with Passive Integrated Transponder (PIT) tags, which allowed movement and growth information to be collected on individual fish. The movements of tagged fish were monitored with a combination of recapture events and stationary in-stream antennas, which detected tagged fish. Meadow Valley Wash within Condor Canyon was divided by a 12-meter (m) waterfall known as Delmue Falls. About 6,100 m of stream were surveyed downstream of the falls and about 2,200 m of stream were surveyed upstream of the falls. Although about three-quarters of the surveyed stream length was downstream of Delmue Falls, the highest densities and abundance of native fish were upstream of the falls. Big Spring spinedace and desert sucker populations were highest near the upper end of Condor Canyon, where a tributary known as Kill Wash, and several springs, contribute flow and moderate high and low water temperature. Kill Wash and the area around its confluence with Meadow Valley Wash appeared important for spawning of all three native species. Detections of PIT-tagged fish indicated that there were substantial movements to this area during the spring. Our surveys included about 700 m of Meadow Valley Wash upstream of Kill Wash. A small falls about 2 m high was about 560 m upstream of Kill Wash. This falls is likely a barrier to upstream fish movement at most flows. Populations of all three native species were found upstream of this small falls. Age-0 fish of all three species were present, indicating successful spawning. The maximum upstream extent of native fish within Meadow Valley Wash was not determined. Our surveys included about 700 m of Meadow Valley Wash upstream of Kill Wash. A small falls about 2 m high was about 560 m upstream of Kill Wash. This falls is likely a barrier to upstream fish movement at most flows. Populations of all three native species were found upstream of this small falls. Age-0 fish of all three species were present, indicating successful spawning. The maximum upstream extent of native fish within Meadow Valley Wash was not determined. A population of non-native rainbow trout (Oncorhynchus mykiss) was found within the 2,000 m of stream immediately downstream of Delmue Falls. Non-native crayfish were very common both upstream and downstream of Delmue Falls. We were not able to quantify crayfish populations, but they compose a significant portion of the biomass of aquatic species in Condor Canyon. There were some distinctive habitat features that may have favored native fish upstream of Delmue Falls. Upstream of the falls, water temperatures were moderated by inputs from springs, turbidity was lower, pool habitat was more prevalent, substrate heterogeneity was higher, and there was less fine sediment than

Open-File Report↗