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At least 91 records · Page 5Linked to original sources
USGS2016

Estimating black bear density in New Mexico using noninvasive genetic sampling coupled with spatially explicit capture-recapture methods

During the 2004–2005 to 2015–2016 hunting seasons, the New Mexico Department of Game and Fish (NMDGF) estimated black bear abundance (Ursus americanus) across the state by coupling density estimates with the distribution of primary habitat generated by Costello et al. (2001). These estimates have been used to set harvest limits. For example, a density of 17 bears/100 km2 for the Sangre de Cristo and Sacramento Mountains and 13.2 bears/100 km2 for the Sandia Mountains were used to set harvest levels. The advancement and widespread acceptance of non-invasive sampling and mark-recapture methods, prompted the NMDGF to collaborate with the New Mexico Cooperative Fish and Wildlife Research Unit and New Mexico State University to update their density estimates for black bear populations in select mountain ranges across the state. We established 5 study areas in 3 mountain ranges: the northern (NSC; sampled in 2012) and southern Sangre de Cristo Mountains (SSC; sampled in 2013), the Sandia Mountains (Sandias; sampled in 2014), and the northern (NSacs) and southern Sacramento Mountains (SSacs; both sampled in 2014). We collected hair samples from black bears using two concurrent non-invasive sampling methods, hair traps and bear rubs. We used a gender marker and a suite of microsatellite loci to determine the individual identification of hair samples that were suitable for genetic analysis. We used these data to generate mark-recapture encounter histories for each bear and estimated density in a spatially explicit capture-recapture framework (SECR). We constructed a suite of SECR candidate models using sex, elevation, land cover type, and time to model heterogeneity in detection probability and the spatial scale over which detection probability declines. We used Akaike’s Information Criterion corrected for small sample size (AICc) to rank and select the most supported model from which we estimated density. We set 554 hair traps, 117 bear rubs and collected 4,083 hair samples. We identified 725 (367 M, 358 F) individuals; the sex ratio for each study area was approximately equal. Our density estimates varied within and among mountain ranges with an estimated density of 21.86 bears/100 km2 (95% CI: 17.83 – 26.80) for the NSC, 19.74 bears/100 km2 (95% CI: 13.77 – 28.30) in the SSC, 25.75 bears/100 km2 (95% CI: 13.22 – 50.14) in the Sandias, 21.86 bears/100 km2 (95% CI: 17.83 – 26.80) in the NSacs, and 16.55 bears/100 km2 (95% CI: 11.64 – 23.53) in the SSacs. Overall detection probability for hair traps and bear rubs, combined, was low across all study areas and ranged from 0.00001 to 0.02. We speculate that detection probabilities were affected by failure of some hair samples to produce a complete genotype due to UV degradation of DNA, and our inability to set and check some sampling devices due to wildfires in the SSC. Ultraviolet radiation levels are particularly high in New Mexico compared to other states where NGS methods have been used because New Mexico receives substantial amounts of sunshine, is relatively high in elevation (1,200 m – 4,000 m), and is at a lower latitude. Despite these sampling difficulties, we were able to produce density estimates for New Mexico black bear populations with levels of precision comparable to estimated black bear densities made elsewhere in the U.S. Our ability to generate reliable black bear density estimates for 3 New Mexico mountain ranges is attributable to our use of a statistically robust study design and analytical method. There are multiple factors that need to be considered when developing future SECR-based density estimation projects. First, the spatial extent of the population of interest and the smallest average home range size must be determined; these will dictate size of the trapping array and spacing necessary between hair traps. The number of technicians needed and access to the study areas will also influence configuration of the trapping array. We believe shorter sampling occasions could be implemented to reduce degradation of DNA due to UV radiation; this might help increase amplification rates and thereby increase both the number of unique individuals identified and the number of recaptures, improving the precision of the density estimates. A pilot study may be useful to determine the length of time hair samples can remain in the field prior to collection. In addition, researchers may consider setting hair traps and bear rubs in more shaded areas (e.g., north facing slopes) to help reduce exposure to UV radiation. To reduce the sampling interval it will be necessary to either hire more field personnel or decrease the number of hair traps per sampling session. Both of these will enhance detection of long-range movement events by individual bears, increase initial capture and recapture rates, and improve precision of the parameter estimates. We recognize that all studies are constrained by limited resources, however, increasing field personnel would also allow a larger study area to be sampled or enable higher trap density. In conclusion, we estimated the density of black bears in 5 study areas within 3 mountains ranges of New Mexico. Our estimates will aid the NMDGF in setting sustainable harvest limits. Along with estimates of density, information on additional demographic rates (e.g., survival rates and reproduction) and the potential effects that climate change and future land use may have on the demography of black bears may also help inform management of black bears in New Mexico, and may be considered as future areas for research.

New Mexico↗
USGS2005

Submersed Aquatic Vegetation Modeling Output Online

Introduction The ability to predict the distribution of submersed aquatic vegetation in the Upper Mississippi River on the basis of physical or chemical variables is useful to resource managers. Wildlife managers have a keen interest in advanced estimates of food quantity such as American wildcelery (Vallisneria americana) population status to give out more informed advisories to hunters before the fall hunting season. Predictions for distribution of submerged aquatic vegetation beds can potentially increase hunter observance of voluntary avoidance zones where foraging birds are left alone to feed undisturbed. In years when submersed aquatic vegetation is predicted to be scarce in important wildlife habitats, managers can get the message out to hunters well before the hunting season (Jim Nissen, Upper Mississippi River National Wildlife and Fish Refuge, La Crosse District Manager, La Crosse, Wisconsin, personal communication). We developed a statistical model to predict the probability of occurrence of submersed aquatic vegetation in Pool 8 of the Upper Mississippi River on the basis of a few hydrological, physical, and geomorphic variables. Our model takes into consideration flow velocity, wind fetch, bathymetry, growing-season daily water level, and light extinction coefficient in the river (fig. 1) and calculates the probability of submersed aquatic vegetation existence in Pool 8 in individual 5- x 5-m grid cells. The model was calibrated using the data collected in 1998 (516 sites), 1999 (595 sites), and 2000 (649 sites) using a stratified random sampling protocol (Yin and others, 2000b). To validate the model, we chose the data from the Long Term Resource Monitoring Program (LTRMP) transect sampling in backwater areas (Rogers and Owens 1995; Yin and others, 2000a) and ran the model for each 5- x 5-m grid cell in every growing season from 1991 to 2001. We tallied all the cells and came up with an annual average percent frequency of submersed aquatic vegetation occurrence and compared the results with actual LTRMP survey data (fig. 2). Both a paired Student's test (P = 0.4620) and a Wilcoxon's two-sample test (P = 0.4738) did not contradict our null hypothesis that the model prediction and the sampling data are statistically the same. We have not found an effective statistical test to compare model-predicted spatial pattern with aerial photography geographic information, but we are satisfied with the model's outcome on the basis of visual inspection (fig. 3). A unique feature about this model is that a prediction can be made by the end of June each year; therefore, providing wildlife managers an assessment of current year vegetation growth condition 3 to 4 months ahead of the arrival of migrating waterfowl that feed on submersed aquatic vegetation. We are working with the LTRMP partnership to create a mechanism so that model predictions (fig. 4) can be updated annually and the results posted on the LTRMP Web site. Our model underestimated the prevalence of vegetation from 2001 to 2004. We speculate that the summer water level reduction conducted in 2001 and 2002 triggered vegetation responses that are outside the model's domain. Future enhancement of the model will incorporate the summer water level drawdown effects as well as the effects of growth conditions in previous years.

Open-File Report↗
USGS2017

Harvest dynamics and annual survival of mallards and grey ducks

We examined how hunter behavior, environmental covariates, and mallard ( Anas platyrhynchos ) and grey duck ( A. superciliosa ) population indices affected per capita harvest, hunter effort (i.e., hours hunted), and hunter participation (i.e., license sales) between 1997 and 2012 in the Eastern Fish and Game Region of New Zealand. Additionally, we examined how total annual hunter effort and harvest affected annual survival and harvest rates (i.e., the proportion of the population that is harvested). Per capita harvest increased with hunter effort and bag limits; hunter effort decreased over time, but effort and participation increased with mallard population size. Juvenile harvest rates were greater than for adults and negatively associated with population size. The relationship between harvest regulations and harvest rates was inconsistent. The 44‐day seasons had greater juvenile harvest rates than the 57‐ and 72‐day seasons. Similarly, years with a 7‐bag limit had higher juvenile harvest rates than years with a 10‐bag limit. Hunter effort affected annual survival rates, especially for females. Alternatively or concordantly, hunter effort may be a surrogate for population size and thus, survival rate may have been density dependent. The relationship between harvest and density‐dependent mortality may in part be augmented by hunter behavior; fewer hunters hunted for fewer hours in years with relatively few birds. Our results suggest bag limits are more effective than season length at managing harvest; reducing bag limits to <2 birds/day from ≥7 could decrease harvest by as much as 50%. Furthermore, regulation consistency, better education, and enforcement of season regulations may improve harvest management; 58% of active hunters reported they shot mallards or grey ducks after the close of the 31‐day season, which accounted for 13% of total harvest.

Journal of Wildlife Management↗
USGS1969

Water resources of the Buffalo River Watershed, West-central Minnesota

The Buffalo River watershed includes two general physiographic areas &ndash; a glacial lake plain and an glacial moraine. The lake plain, which was formed by Glacial lake Agassiz more than 9,000 years ago, is extremely flat &ndash; sloping only a few feet per mile westward near the Red River of the North. The moraine is largely an area of gently rolling hills, but in the eastern &ldquo;tail&rdquo; of the watershed the relief locally is over two hundred feet. The watershed has an area of about 1,690 square miles and includes most of Clay County and parts of Wilkin, Otter Tail, Becker, and Norman Counties. The population of the area is about 45,500 &ndash; 31,000 urban and 14,500 rural. The economy is largely agricultural. Sugar beet and wheat farming are dominant in the areas of clay and silt; potato farming is confined mainly to the sandy areas. Dairying and stock raising is important in the morainal area. The larger industries are located in Moorhead and consist of sugar beet, potato, and dairy product processing. Water-based recreation consists mostly of fishing in the larger lakes in the morainal area, and water-fowl hunting in the area of prairie potholes &ndash; the western part of the morainal area.

Minnesota↗
USGS2002

Conditions and limitations on learning in the adaptive management of mallard harvests

In 1995, the United States Fish and Wildlife Service adopted a protocol for the adaptive management of waterfowl hunting regulations (AHM) to help reduce uncertainty about the magnitude of sustainable harvests. To date, the AHM process has focused principally on the midcontinent population of mallards (Anas platyrhynchos), whose dynamics are described by 4 alternative models. Collectively, these models express uncertainty (or disagreement) about whether harvest is an additive or a compensatory form of mortality and whether the reproductive process is weakly or strongly density-dependent. Each model is associated with a probability or 'weight,' which describes its relative ability to predict changes in population size. These Bayesian probabilities are updated annually using a comparison of population size predicted under each model with that observed by a monitoring program. The current AHM process is passively adaptive, in the sense that there is no a priori consideration of how harvest decisions might affect discrimination among models. We contrast this approach with an actively adaptive approach, in which harvest decisions are used in part to produce the learning needed to increase long-term management performance. Our investigation suggests that the passive approach is expected to perform nearly as well as an optimal actively adaptive approach, particularly considering the nature of the model set, management objectives and constraints, and current regulatory alternatives. We offer some comments about the nature of the biological hypotheses being tested and describe some of the inherent limitations on learning in the AHM process.

Wildlife Society Bulletin↗
USGS2020

Assessing native fish restoration potential in Catoctin Mountain Park

Biological conservation is a fundamental purpose of the National Park system, and Catoctin Mountain Park (CATO) supports high-quality habitat for native fishes in the headwaters of the Chesapeake Bay watershed in eastern North America. However, native Blue Ridge sculpin ( Cottus caeruleomentum ) have been extirpated in Big Hunting Creek above Cunningham Falls in CATO. Prior research indicates that infection by the fungal-like protist Dermocystidium is a likely cause for the extirpation, but elevated stream temperatures also have been observed in the study area, and it remains unknown whether thermal stress may exacerbate infections or otherwise limit habitat suitability for fishes in CATO. The purpose of this study was to quantify spatial variation in summer stream temperatures and to evaluate the effects of temperature on sculpin growth rates and susceptibility to Dermocystidium infection. We used observational and experimental methods to address these objectives. First, we deployed stream temperature gages at 10 sites throughout the study area to assess hourly and daily temperatures during the summer of 2019. Second, we conducted an in situ fish enclosure experiment at five of the temperature sites to assess fish growth and susceptibility to Dermocystidium infection over a 45-day exposure period. For this experiment we collected sculpin from a stream in CATO that supports a robust population of Blue Ridge sculpin (Owens Creek) and held them in quarantine for 50 days in the Experimental Stream Laboratory at the U.S. Geological Survey (USGS) Leetown Science Center. Pre-exposure histopathology confirmed the absence of Dermocystidium infection prior to the introduction of fish into experimental enclosures. We found that stream temperatures were warmer where sculpin have been extirpated than elsewhere in CATO where sculpin persist. However, the fish enclosure experiment revealed a positive effect of temperature on fish growth, suggesting that increased food availability and foraging rates compensated for increased metabolic demands in the warmest sites. Moreover, fish held in enclosures did not develop Dermocystidium infection. Our results therefore suggest that current environmental conditions in upper Big Hunting Creek may be suitable for Blue Ridge sculpin reintroduction, and this could ultimately lead to sportfishing opportunities by increasing the forage base for native brook trout ( Salvelinus fontinalis ).

Maryland↗
USGS2017

U.S. Geological Survey—Energy and wildlife research annual report for 2017

Introduction Terrestrial and aquatic ecosystems provide valuable services to humans and are a source of clean water, energy, raw materials, and productive soils. The Nation’s food supply is more secure because of wildlife. For example, native pollinators enhance agricultural crops, and insect-eating bats provide pest control services worth billions of dollars to farmers annually. Fish and wildlife are also vital to a vibrant outdoor recreation and tourism industry. Recreational activities, such as hunting, shooting, boating, and angling, generated \$1.1 billion in excise taxes paid to State wildlife agencies in 2017. National parks, wildlife refuges, and monuments accounted for $35 billion in economic output and 318,000 jobs nationwide in 2016. Additional economic benefits are generated from the use and enjoyment of wildlife in State-owned lands and waters. Although the United States is rich in natural resources, human activity continues to place new pressures on fish and wildlife and the habitats they rely on. The United States became the world’s top producer of petroleum and natural gas products in 2012, surpassing Russia’s natural gas production levels in 2009 and Saudi Arabia’s petroleum production in 2013. The U.S. Energy Information Administration projects that the demand for liquid fuel, natural gas, and renewable energy will show strong growth in the next 20 years. Wind energy has demonstrated consistent growth since 2007 with now more than 53,000 wind turbines contributing to power grids in 41 States, Guam, and Puerto Rico. Solar energy has seen rapid growth since 2013 and made up nearly one-third of the total electricity generation additions in 2016. Yet as our Nation works to advance energy security and sustain wildlife, some conflicts have surfaced. Impacts of an expanding energy infrastructure include fragmentation and loss of habitat as well as mortality of birds, bats, fish, and other animals from interactions with energy generation facilities. Because energy development can often occur in wildlife habitats, ecological science can help guide project siting and operational decisions to areas that present the lowest risk to wildlife and energy developers. To address these challenges and make the most of new opportunities, the U.S. Geological Survey is producing innovative science to develop workable solutions that can help sustain wildlife and the habitat they rely upon, while allowing informed development.

Circular↗
USGS2025

Estimating the social and economic consequences of proposed management alternatives at the National Elk Refuge

The National Elk Refuge (Refuge) is managed by the U.S. Fish and Wildlife Service and includes habitats for bison and elk. Bison and elk provide opportunities for wildlife-related recreation and contribute to the tourism industry in and around Jackson, Wyoming. Over the last century, the Refuge has provisioned supplemental feed to elk and, more recently, bison during winter months to ensure adequate forage and prevent starvation and conflict with private landowners. However, supplemental feeding artificially aggregates animals and can increase rates of disease transmission and localized damage to sensitive habitats near the feeding areas. This report presents analyses and results to support two of the nine management objectives in the next “Bison and Elk Management Plan,” with a particular focus on the social and economic consequences of five management alternatives considered in this study. The alternatives are to continue feeding bison and elk during winter months on the Refuge, stop feeding after CWD is measured at 3 percent prevalence or above in the Jackson elk herd, stop feeding immediately, reduce feeding for five years and then stop feeding, and increase elk harvest for five years and then stop feeding. These alternatives are anticipated to alter bison and elk population and space-use dynamics, with corresponding effects on wildlife-related recreation and tourism, including the number of visitors and sleigh-ride participants on the Refuge, and hunters and outfitters within the Jackson Elk Herd Unit. The performance of each of this study’s alternatives was variable, resulting in overlap in the performance of alternatives on the select objectives over the next 20 years. Generally, visitation-related objectives performed better under the continue feeding alternative, whereas hunting-related objectives performed better under the increase harvest alternative. The results presented here may assist U.S. Fish and Wildlife Service decision makers in balancing social and economic benefits identified in the decision-making process for the “Bison and Elk Management Plan” with other objectives evaluated in this report.

Wyoming↗
USGS2025

Estimating the social and economic consequences of proposed management alternatives at the National Elk Refuge in Jackson, Wyoming

The National Elk Refuge (Refuge) is managed by the U.S. Fish and Wildlife Service and includes habitats for bison and elk. Bison and elk provide opportunities for wildlife-related recreation and contribute to the tourism industry in and around Jackson, Wyoming. Over the last century, the Refuge has provisioned supplemental feed to elk and, more recently, bison during winter months to ensure adequate forage and prevent starvation and conflict with private landowners. However, supplemental feeding artificially aggregates animals and can increase rates of disease transmission and localized damage to sensitive habitats near the feeding areas. This report presents analyses and results to support two of the nine management objectives in the next “Bison and Elk Management Plan,” with a particular focus on the social and economic consequences of five management alternatives considered in this study. The alternatives are to continue feeding bison and elk during winter months on the Refuge, stop feeding after CWD is measured at 3 percent prevalence or above in the Jackson elk herd, stop feeding immediately, reduce feeding for five years and then stop feeding, and increase elk harvest for five years and then stop feeding. These alternatives are anticipated to alter bison and elk population and space-use dynamics, with corresponding effects on wildlife-related recreation and tourism, including the number of visitors and sleigh-ride participants on the Refuge, and hunters and outfitters within the Jackson Elk Herd Unit. The performance of each of this study’s alternatives was variable, resulting in overlap in the performance of alternatives on the select objectives over the next 20 years. Generally, visitation-related objectives performed better under the continue feeding alternative, whereas hunting-related objectives performed better under the increase harvest alternative. The results presented here may assist U.S. Fish and Wildlife Service decision makers in balancing social and economic benefits identified in the decision-making process for the “Bison and Elk Management Plan” with other objectives evaluated in this report.

Wyoming↗
USGS2021

A bright spot analysis of inland recreational fisheries in the face of climate change: Learning about adaptation from small successes

Inland recreational fisheries have social, economic, and ecological importance worldwide but these fisheries are increasingly challenged by the diverse effects of climate change. Coupled with other anthropogenic stressors, climate change has contributed to declines in freshwater biodiversity of greater severity than those observed across marine or terrestrial taxa. At a macro level, inland fisheries are experiencing declines. There are, however, a number of success stories, or ‘bright spots,’ in inland recreational fisheries management, where innovative approaches are leading to increases in social and ecological well-being in the face of climate change. Cases such as these are important sources of inspiration and learning about adaptation to climate and environmental change. In this article, we analyze 11 examples of such ‘bright spots’ drawn from multiple jurisdictions around the world from which we extracted lessons that might apply to fisheries management challenges beyond the region and context of each case. Collectively, these bright spots highlight adaptive initiatives that allow for recreational fisheries management to mitigate to stressors associated with current and future climate change. Examples identified include community-based restoration projects, collaborative and adaptive approaches to short-term fisheries closures, transdisciplinary large-scale conservation projects, and conservation-minded efforts by individuals and communities. By highlighting examples of ‘small wins’ within inland recreational fisheries management, this review contributes to the idea that a ‘positive future’ for inland recreational fisheries in the face of climate change is possible and highlights potential strategies to adapt to current and future climate scenarios.

Reviews in Fish Biology and Fisheries↗
USGS2007

Simulation of Hydrologic-System Responses to Ground-Water Withdrawals in the Hunt-Annaquatucket-Pettaquamscutt Stream-Aquifer System, Rhode Island

A numerical-modeling study was done to better understand hydrologic-system responses to ground-water withdrawals in the Hunt-Annaquatucket-Pettaquamscutt (HAP) stream-aquifer system of Rhode Island. System responses were determined by use of steady-state and transient numerical ground-water-flow models. These models were initially developed in the late 1990s as part of a larger study of the stream-aquifer system. The models were modified to incorporate new data made available since the original study and to meet the objectives of this study. Changes made to the models did not result in substantial changes to simulated ground-water levels, hydrologic budgets, or streamflows compared to those calculated by the original steady-state and transient models. Responses of the hydrologic system are described primarily by changes in simulated streamflows and ground-water levels throughout the basin and by changes to flow conditions in the aquifer in three wetland areas immediately east of the Lafayette State Fish Hatchery, which lies within the Annaquatucket River Basin in the town of North Kingstown. Ground water is withdrawn from the HAP aquifer at 14 large-capacity production wells, at an industrial well, and at 3 wells operated by the Rhode Island Department of Environmental Management at the fish hatchery. A fourth well has been proposed for the hatchery and an additional production well is under development by the town of North Kingstown. The primary streams of interest in the study area are the Hunt, Annaquatucket, and Pettaquamscutt Rivers and Queens Fort Brook. Total model-calculated streamflow depletions in these rivers and brook resulting from withdrawals at the production, industrial, and fish-hatchery wells pumping at average annual 2003 rates are about 4.8 cubic feet per second (ft3/s) for the Hunt River, 3.3 ft3/s for the Annaquatucket River, 0.5 ft3/s for the Pettaquamscutt River, and 0.5 ft3/s for Queens Fort Brook. The actual amount of streamflow reduction in the Annaquatucket River caused by pumping actually is less, 1.1 ft3/s, because ground water that is pumped at the fish-hatchery wells (2.2 ft3/s) is returned to the Annaquatucket River after use at the hatchery. One of the primary goals of the study was to evaluate the response of the hydrologic system to simulated withdrawals at the proposed well at the fish hatchery. Withdrawal rates at the proposed well would range from zero during April through September of each year to a maximum of 260 gallons per minute [about 0.4 million gallons per day (Mgal/d)] in March of each year. The average annual withdrawal rate at the fish hatchery resulting from the addition of the proposed well would increase by only 0.13 ft3/s, or about 5 percent of the 2003 withdrawal rate. The increased pumping rate at the hatchery would further reduce the average annual flow in Queens Fort Brook by less than 0.05 ft3/s and in the Annaquatucket River by about 0.1 ft3/s (which includes some model error). A new production well in the Annaquatucket River Basin is under development by the town of North Kingstown. A simulated pumping rate of 1.0 Mgal/d (1.6 ft3/s) at this new well resulted in additional streamflow depletions, compared to those calculated for the 2003 withdrawal conditions, of 0.8 and 0.2 ft3/s in the Annaquatucket and Pettaquamscutt Rivers, respectively. The source of water for about 30 percent of the well's pumping rate, or about 0.5 ft3/s, is derived from ground-water inflow from the Chipuxet River Basin across a natural ground-water drainage divide that separates the Annaquatucket and Chipuxet River Basins; the remaining 0.1 ft3/s of simulated pumping consists of reduced evapotranspiration from the water table. Model-calculated changes in water levels in the aquifer for the various withdrawal conditions simulated in this study indicate that ground-water-level declines caused by pumping are generally less than 5 feet (ft). However, ground-water-level declines of as

Open-File Report↗
USGS2020

Review of methods to repair and maintain lithophilic fish spawning habitat

Rocky reefs provide important spawning and refuge habitats for lithophilic spawning fishes. However, many reefs have been lost or severely degraded through anthropogenic effects like dredging, channelization, or sedimentation. Constructed reefs have been used to mitigate these effects in some systems, but these reefs are also subject to degradation which may warrant custodial maintenance. Monitoring and maintenance of natural or constructed spawning reefs are not common practices; therefore, few methodologies have been created to test the effectiveness of such tools. We conducted a literature review to assess available information on maintenance of rocky spawning habitats used by lithophilic fishes. We identified 54 rocky spawning habitat maintenance projects, most of which aimed to improve fish spawning habitats through the addition of spawning substrate ( n = 33) or cleaning of substrate ( n = 23). In comparison to shallow riverine studies focused on salmonids, we found little information on deep-water reefs, marine reefs, or other fish species. We discuss the possible application of potential spawning habitat cleaning methods from other disciplines (e.g., treasure hunting; archeology) that may provide effective means of reef maintenance that can be used by restoration practitioners.

Water↗
USGS1992

Management of habitat for breeding and migrating shorebirds in the Midwest

Shorebirds have always relied on the extensive network of natural wetlands from Texas to North Dakota. This network has now been fractured by wetland drainage and agriculture to the point where suitable wetlands are absent in much of the Midwest. Habitat loss and the resulting risk of population decline highlight the importance of management of shorebirds on refuges, hunting clubs, and preserves for both breeding and migrating species.

Fish and Wildlife Leaflet↗
USGS1994

A review of lead poisoning in swans

Nearly 10,000 swans of six species or subspecies from 14 countries have died from poisoning caused by lead that originated from ingestion of fishing weights, shotgun pellets (shot), or contaminated vegetation or sediments associated with mining and smelting wastes. Lead contamination in mute swans in England caused local population declines during the late 1970s and 1980s. More tundra swans died from lead poisoning than any other species. The extreme record involved an estimated 7200 tundra swans that died over five winters at one locality in North Carolina. The recent legislation to ban lead fishing weights in most of England and Wales and recent replacement of lead shot with steel shot for waterfowl hunting in the United States and a few areas of Europe, including Denmark, are expected to reduce the incidence of lead poisoning in swans.

Comparative Biochemistry and Physiology, Part C: P↗
USGS1977

Impact of estuarine pollution on birds

Pollution of estuaries affects bird populations indirectly through changes in habitat and food supply. The multi-factor pollution of Chesapeake Bay has resulted in diminution of submerged aquatic plants and consequent change in food habits of the canvasback duck. Although dredge-spoil operations can improve wildlife habitat, they often result in its demise. Pollution of estuaries also affects birds directly, through chemical toxication, which may result in outright mortality or in reproductive impairment. Lead from industrial sources and roadways enters the estuaries and is accumulated in tissues of birds. Lead pellets deposited in estuaries as a result of hunting are consumed by ducks with sufficient frequency .to result m large annual die-offs from lead poisoning. Fish in certain areas, usually near industrial sources, may contain levels of mercury high enough to be hazardous to birds that consume them. Other heavy metals are present in estuarine birds, but their significance is poorly known. Oil exerts lethal or sublethal effects on birds by oiling their feathers, oiling eggs and young by contaminated parents, and by ingestion of oil-contaminated food. Organochlorine chemicals, of both agricultural and industrial origin, travel through the food chains and reach harmful levels in susceptible species of birds in certain estuarine ecosystems. Both outright mortality and reproductive impairment have occurred.

Book chapter↗
USGS2014

The persistent problem of lead poisoning in birds from ammunition and fishing tackle

Lead (Pb) is a metabolic poison that can negatively influence biological processes, leading to illness and mortality across a large spectrum of North American avifauna (>120 species) and other organisms. Pb poisoning can result from numerous sources, including ingestion of bullet fragments and shot pellets left in animal carcasses, spent ammunition left in the field, lost fishing tackle, Pb-based paints, large-scale mining, and Pb smelting activities. Although Pb shot has been banned for waterfowl hunting in the United States (since 1991) and Canada (since 1999), Pb exposure remains a problem for many avian species. Despite a large body of scientific literature on exposure to Pb and its toxicological effects on birds, controversy still exists regarding its impacts at a population level. We explore these issues and highlight areas in need of investigation: (1) variation in sensitivity to Pb exposure among bird species; (2) spatial extent and sources of Pb contamination in habitats in relation to bird exposure in those same locations; and (3) interactions between avian Pb exposure and other landscape-level stressors that synergistically affect bird demography. We explore multiple paths taken to reduce Pb exposure in birds that (1) recognize common ground among a range of affected interests; (2) have been applied at local to national scales; and (3) engage governmental agencies, interest groups, and professional societies to communicate the impacts of Pb ammunition and fishing tackle, and to describe approaches for reducing their availability to birds. As they have in previous times, users of fish and wildlife will play a key role in resolving the Pb poisoning issue.

The Condor↗