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USGS2024

Effects of noise from oil and gas development on raptors and songbirds—A science synthesis to inform National Environmental Policy Act analyses

The U.S. Geological Survey is working with Federal land management agencies to develop a series of science syntheses to support environmental effects analyses that agencies conduct to comply with the National Environmental Policy Act (NEPA). This report synthesizes science information about the potential effects of noise from oil and gas development on North American raptors, songbirds, and other small avian species. We conducted a structured search of published scientific literature to find information about noise levels produced during oil and gas development, methods for analyzing sound propagation, the effects of noise on avian species, and measures to reduce noise emissions. We follow the organization first established in U.S. Geological Survey Scientific Investigations Report 2023-5114, in which the report sections align with standard elements of NEPA analyses. We found that oil and gas development is a common source of human-caused noise on public lands and includes noise sources such as heavy construction and drilling machinery, long-term production machinery, truck traffic, and aircraft. Common techniques for predicting potential noise include field data collection using a sound level meter, inference from previously published data, and sound propagation modeling. The effects of human-caused noise on songbirds are well researched, whereas, among raptors, only owl species have been well-studied in relation to noise. Several studies have established that noise can reduce owl hunting success because many owl species are heavily reliant on hearing prey when hunting. The effects of noise on songbirds depend on several factors. Typically, birds that rely on vocal communication for mating, predator detection, and spatial orientation, and that are less able to adjust the frequencies of their vocalizations, are more vulnerable to behavioral changes and decreased fitness in noisy areas. Techniques suggested in the literature for reducing noise emissions include artificial sound barriers, seasonal and daily timing restrictions, traffic control measures, and siting infrastructure to take advantage of natural sound barriers. Public land managers can use this report by incorporating it by reference in NEPA documentation, as supplemental information, or as a general reference to find literature or identify gaps in the literature about the effects of noise from oil and gas development on raptors and songbirds.

Scientific Investigations Report↗

USGS2015

Surveillance potential of non-native Hawaiian birds for detection of West Nile Virus

West Nile virus (WNV) was first detected in North America in 1999. Alaska and Hawaii (HI) remain the only U.S. states in which transmission of WNV has not been detected. Dead bird surveillance has played an important role in the detection of the virus geographically, as well as temporally. In North America, corvids have played a major role in WNV surveillance; however, the only corvid in HI is the endangered Hawaiian crow that exists only in captivity, thus precluding the use of this species for WNV surveillance in HI. To evaluate the suitability of alternate avian species for WNV surveillance, we experimentally challenged seven abundant non-native bird species present in HI with WNV and compared mortality, viremia, oral shedding of virus, and seroconversion. For detection of WNV in oral swabs, we compared viral culture, reverse-transcriptase polymerase chain reaction, and the RAMP ® test. For detection of antibodies to WNV, we compared an indirect and a competitive enzyme-linked immunoassay. We found four species (house sparrow, house finch, Japanese white-eye, and Java sparrow) that may be useful in dead bird surveillance for WNV; while common myna, zebra dove, and spotted dove survived infection and may be useful in serosurveillance.

American Journal of Tropical Medicine and Hygiene↗

USGS1986

Potential impacts of agricultural chemicals on waterfowl and other wildlife inhabiting prairie wetlands: An evaluation of research needs and approaches

The potential for agricultural chemicals to enter prairie-pothole wetlands and impact wildlife dependent on these wetlands for survival and reproduction appears to be great. However, the actual risk to wetland wildlife from the inputs of these chemicals cannot be adequately assessed at this time, because of insufficient data. Available data on the use of pesticides in the prairie-pothole region and the toxicity of these pesticides suggest that insecticides pose the greatest hazard to wetland wildlife, particularly birds. The majority of the most widely used insecticides within the region are very toxic to aquatic invertebrates and birds. Of particular concern are the impacts of agricultural chemicals on the quality of the remaining wetlands in the region and whether or not these impacts have contributed to observed declines in waterfowl populations. Although existing data suggest that adult and juvenile waterfowl may not be more sensitive to these chemicals than are other wetland wildlife, their food habits and feeding behaviors may make them more vulnerable to direct toxic effects or chemical-induced changes in the abundance of aquatic invertebrates. Laboratory and field studies in the United States and Canada are critically needed to assess these potential impacts.

Transactions of the North American Wildlife and Na↗

USGS1983

Organochlorine pesticides and PCB's: A continuing problem for the 1980s

In general. decreases in OC contamination in North America are unmistakable. This is documented by the NPMP. but. more importantly. it is borne out by improvements in the reproduction and population status of the brown pelican. bald eagle, peregrine falcon, and osprey. However, some OC contamination still persists, and several species, particularly predatory birds and insectivorous bats, continue to be vulnerable. Current OC problems in North America result from present and past usage and from industrial contamination. In addition, some studies suggest that some migrant bird species that winter south of the U.S. border are exposed to higher levels of OC pesticide than non-migrants. However, heavy OC pesticide contamination is known to exist in Arizona, New Mexico, and in southern California where migratory birds might stop during migration. At this time, we do not have the information to assess specifically the sources of contamination for most migrant species. From the number of recent OC problems identified in North America, it is apparent that OC's are not confined to the past and that we must continue to monitor and study OC's during this decade. However, current administrative, management, and research priorities are being directed toward the search for potential impacts of newer pesticides, air pollution. industrial waste, and other contaminants. Although it is necessary to build a body of scientific data on these types of contaminants, we feel that we cannot neglect continued work on OC's for which harmful effects impacting our wildlife resources are already known.

Transactions of the North American Wildlife and Na↗

USGS2010

North American osprey populations and contaminants: Historic and contemporary perspectives

Osprey ( Pandion haliaetus ) populations were adversely affected by DDT and perhaps other contaminants in the United States and elsewhere. Reduced productivity, eggshell thinning, and high DDE concentrations in eggs were the signs associated with declining osprey populations in the 1950s, 1960s, and 1970s. The species was one of the first studied on a large scale to bring contaminant issues into focus. Although few quantitative population data were available prior to the 1960s, many osprey populations in North America were studied during the 1960s and 1970s with much learned about basic life history and biology. This article reviews the historical and current effects of contaminants on regional osprey populations. Breeding populations in many regions of North America showed post-DDT-era (1972) population increases of varying magnitudes, with many populations now appearing to stabilize at much higher numbers than initially reported in the 1970s and 1980s. However, the magnitude of regional population increases in the United States between 1981 (first Nationwide Survey, ∼8,000 pairs), when some recovery had already occurred, 1994 (second survey, ∼14,200), and 2001 (third survey, ∼16,000–19,000), or any other years, is likely not a simple response to the release from earlier contaminant effects, but a response to multi-factorial effects. This indirect “contaminant effects” measurement comparing changes (i.e., recovery) in post-DDT-era population numbers over time is probably confounded by changing human attitudes toward birds of prey (shooting, destroying nests, etc.), changing habitats, changing fish populations, and perhaps competition from other species. The species' adaptation to newly created reservoirs and its increasing use of artificial nesting structures (power poles, nesting platforms, cell towers, channel markers, offshore duck blinds, etc.) are two important factors. The timing of the initial use of artificial nesting structures, which replaced declining numbers of suitable trees at many locations, varied regionally (much later in the western United States and Mexico). Because of the increasing use of artificial nesting structures, there may be more ospreys nesting in North America now than ever before. Now, with the impact of most legacy organic contaminants (DDT, other organochlorine [OC] pesticides, polychlorinated biphenyls [PCB], polychlorinated dibenzo- p -dioxins [PCDD], polychlorinated dibenzofurans (PCDF]) greatly reduced or eliminated, and some osprey populations showing evidence of stabilizing, the species was proposed as a Worldwide Sentinel Species for evaluating emerging contaminants. Several emerging contaminants are already being studied, such as polybrominated diphenyl ethers (PBDE) and perfluorinated acids and sulfonate compounds (PFC). The many advantages for continued contaminant investigations using the osprey include a good understanding of its biology and ecology, its known distribution and abundance, and its ability to habituate to humans and their activities, which permits nesting in some of the potentially most contaminated environments. It is a top predator in most ecosystems, and its nests are relatively easy to locate and study with little researcher impact on reproductive success.

Journal of Toxicology and Environmental Health, Pa↗

USGS2008

Survival of the faucet snail after chemical disinfection, pH extremes, and heated water bath treatments

The faucet snail Bithynia tentaculata, a nonindigenous aquatic snail from Eurasia, was introduced into Lake Michigan in 1871 and has spread to the mid-Atlantic states, the Great Lakes region, Montana, and most recently, the Mississippi River. The faucet snail serves as intermediate host for several trematodes that have caused large-scale mortality among water birds, primarily in the Great Lakes region and Montana. It is important to limit the spread of the faucet snail; small fisheries equipment can serve as a method of snail distribution. Treatments with chemical disinfection, pH extremes, and heated water baths were tested to determine their effectiveness as a disinfectant for small fisheries equipment. Two treatments eliminated all test snails: (1) a 24-h exposure to Hydrothol 191 at a concentration of at least 20 mg/L and (2) a treatment with 50°C heated water for 1 min or longer. Faucet snails were highly resistant to ethanol, NaCl, formalin, Lysol, potassium permanganate, copper sulfate, Baquacil, Virkon, household bleach, and pH extremes (as low as 1 and as high as 13).

Wisconsin↗

USGS2004

Abundance estimation and conservation biology

Abundance is the state variable of interest in most population–level ecological research and in most programs involving management and conservation of animal populations. Abundance is the single parameter of interest in capture–recapture models for closed populations (e.g., Darroch, 1958; Otis et al., 1978; Chao, 2001). The initial capture–recapture models developed for partially (Darroch, 1959) and completely (Jolly, 1965; Seber, 1965) open populations represented efforts to relax the restrictive assumption of population closure for the purpose of estimating abundance. Subsequent emphases in capture–recapture work were on survival rate estimation in the 1970’s and 1980’s (e.g., Burnham et al., 1987; Lebreton et al.,1992), and on movement estimation in the 1990’s (Brownie et al., 1993; Schwarz et al., 1993). However, from the mid–1990’s until the present time, capture–recapture investigators have expressed a renewed interest in abundance and related parameters (Pradel, 1996; Schwarz & Arnason, 1996; Schwarz, 2001). The focus of this session was abundance, and presentations covered topics ranging from estimation of abundance and rate of change in abundance, to inferences about the demographic processes underlying changes in abundance, to occupancy as a surrogate of abundance. The plenary paper by Link & Barker (2004) is provocative and very interesting, and it contains a number of important messages and suggestions. Link & Barker (2004) emphasize that the increasing complexity of capture–recapture models has resulted in large numbers of parameters and that a challenge to ecologists is to extract ecological signals from this complexity. They offer hierarchical models as a natural approach to inference in which traditional parameters are viewed as realizations of stochastic processes. These processes are governed by hyperparameters, and the inferential approach focuses on these hyperparameters. Link & Barker (2004) also suggest that our attention should be focused on relationships between demographic processes such as survival and recruitment, the two quantities responsible for changes in abundance, rather than simply on the magnitudes of these quantities. They describe a type of Jolly–Seber capture–recapture model that permits inference about the underlying relationship between per capita recruitment rates and survival rates (Link & Barker, this volume). Implementation used Bayesian Markov Chain Monte Carlo methods and appeared to work well, yielding inferences about the relationship between recruitment and survival that were robust to selection of prior distribution. We believe that readers will find their arguments compelling, and we expect to see increased use of hierarchical modeling approaches in capture–recapture and related fields. Otto (presentation without paper) also recommended use of hierarchical models in analysis of multiple data sources dealing with population dynamics of North American mallards. He integrated survival inferences from ringing data, abundance information from aerial survey data, and recruitment information based on age ratios from a harvest survey. He used a Leslie matrix population projection model as an integrating framework and obtained estimates of breeding population size using all data.Otto’s approach also permitted inference about biases in estimated quantities. As with the work of Link & Barker (2004), we find Otto’s recommendation to use hierarchical models to integrate data from multiple sources to be very compelling. Alisauskas et al. (2004) report results of an analysis of capture–recapture data for a askatchewan population of white–winged scoters. They used the approach of Pradel (1996) to estimate population growth rate (See the PDF) directly. Estimates for 1975–1985 were quite low, but estimates for the recent period, 2000–2003,increased to values > 1. Parameter estimates for seniority, survival and per capita recruitment (Pradel, 1996) led to the inference that increased recruitment was largely responsible for the improvements in population status and growth. However, various data sources also indicated that this increase in recruitment was likely a result of increased immigration rather than improved reproduction on the area. This latter inference is important from a conservation perspective in indicating the importance of birds in other locations to growth and health of the study population. Lukacs and Burnham presented material to be published elsewhere that dealt with the use of genetic markers in capture–recapture studies. The data sources for such studies are samples of hair or feces, which are then analyzed using molecular genetic techniques in order to determine individual genotypes with respect to a usually small number of loci. Two types of classification error can arise in such analyses. First, if only a small number of loci is examined, then there may be nonnegligible probabilities that multiple individual animals will have the same genotypes. The second type of error arises during the polymerase chain reaction (PCR) process and can result from failure of alleles to amplify (allelic dropout) or from PCR inhibitors in hair and feces that produce the appearance of false alleles or misprinting (Creel et al., 2003). Lukacs and Burnham developed models that formally incorporate possible misclassification of samples resulting from these errors. These models permit estimation of parameters such as abundance and survival in a manner that properly incorporates this uncertainty of individual identity. We anticipate that noninvasive sampling based on molecular genetic analyses of hair or feces will become extremely important for some species, and that the models of Lukacs and Burnham will become very popular for such analyses. MacKenzie & Nichols (2004) discuss the use of occupancy (proportion of patches or habitat area that is occupied) as a surrogate for abundance. In cases of territorial species and where birds occur at low densities, the number of occupied patches may provide a reasonable estimate of abundance. In other cases, occupancy can be viewed as providing information about one tail of the abundance distribution, P (N = 0). The motivation for considering occupancy as a surrogate for abundance is that occupancy is based on so–called presence–absence surveys that are frequently less expensive of time and effort than methods that estimate abundance directly. We describe one set of models that can be used to estimate occupancy for a single season and another that can be used to estimate parameters such as local probabilities of extinction and colonization that are associated with occupancy dynamics. We outline a possible hybrid approach that combines occupancy data with data on marked individuals in order to betterexplore the mechanisms underlying occupancy dynamics. These five presentations made for an interesting session containing useful information and recommendations for future work. A number of themes connecting these presentations could be emphasized. For example, two of the presentations considered alternatives to standard capture–recapture sampling that can be used to draw inferences about abundance, or a portion of the abundance distribution, with field methods that should be less expensive than usual capture–recapture approaches of handling animals. We believe that the most important theme of the session was the emphasis on the processes responsible for changes in abundance. In particular, we are excited by the potential for using hierarchical models as a means of investigating relationships among vital rates and as a means of combining multiple sources of data relevant to system dynamics. Indeed, we expect the importance of this session theme to be reflected in the content and presentations of the next EURING meeting.

Animal Biodiversity and Conservation↗

USGS2015

Genetic diversity and host specificity varies across three genera of blood parasites in ducks of the Pacific Americas Flyway

Birds of the order Anseriformes, commonly referred to as waterfowl, are frequently infected by Haemosporidia of the genera Haemoproteus , Plasmodium , and Leucocytozoon via dipteran vectors. We analyzed nucleotide sequences of the Cytochrome b (Cyt b ) gene from parasites of these genera detected in six species of ducks from Alaska and California, USA to characterize the genetic diversity of Haemosporidia infecting waterfowl at two ends of the Pacific Americas Flyway. In addition, parasite Cyt b sequences were compared to those available on a public database to investigate specificity of genetic lineages to hosts of the order Anseriformes. Haplotype and nucleotide diversity of Haemoproteus Cyt b sequences was lower than was detected for Plasmodium and Leucocytozoon parasites. Although waterfowl are presumed to be infected by only a single species of Leucocytozoon , L . simondi , diversity indices were highest for haplotypes from this genus and sequences formed five distinct clades separated by genetic distances of 4.9%–7.6%, suggesting potential cryptic speciation. All Haemoproteus and Leucocytozoon haplotypes derived from waterfowl samples formed monophyletic clades in phylogenetic analyses and were unique to the order Anseriformes with few exceptions. In contrast, waterfowl-origin Plasmodium haplotypes were identical or closely related to lineages found in other avian orders. Our results suggest a more generalist strategy for Plasmodium parasites infecting North American waterfowl as compared to those of the genera Haemoproteus and Leucocytozoon .

PLoS ONE↗

USGS1975

Death feigning by ducks in response to predation by red foxes (Vulpes fulva)

Predation by captive red foxes ( Vulpes fulva ) on approximately 50 ducks comprised of five species was observed in tests conducted at the Northern Prairie Wildlife Research Center, Jamestown, North Dakota. Most ducks were attacked from a rear or lateral position and seized in the cervical or thoracic region. All birds became immobile (death-feigned) immediately when seized and with few exceptions remained motionless during prey-handling and for varying lengths of time thereafter. Initial death feints lasted from 20 sec to 14 min. Recovery was delayed by tactile, visual and, possibly, auditory cues from the foxes. Death-feigning birds appeared alert and often took advantage of escape opportunities. Twenty-nine birds survived initial capture and handling by the foxes. Naive foxes were wary of ducks during initial confrontations, but experienced foxes showed little hesitation in attacking them. After capture, most ducks were taken alive to lay-down sites where they were mouthed and often killed. Then the ducks were usually cached or taken to dens or pups. Several birds were cached alive. Red foxes appear to have adapted to the escape of death-feigning ducks by learning to kill some birds soon after capture and by the evolution of an appendage-severing behavior. Death feigning appears to be a highly developed antipredator behavior of ducks that facilitates the escape of some birds after capture by red foxes.

American Midland Naturalist↗

USGS1980

Consistency in habitat preference of forest bird species

The important management conclusion that follows from our results is that the habitat requirements of most forest bird species, although quite specific for each species, apply generally throughout their breeding ranges. Thus a habitat management program that proves beneficial in one part of the breeding range of a species has a high likelihood of success in an area hundreds of kilometers away. Site-specific programs may be necessary for successful management of species whose habitat preferences change across their range. Alternatively, geographical variation in habitat use may indicate that a species' habitat requirements are easily met and that effective management for the species is more readily attained. Close monitoring of a species' response to specific management programs will be required to resolve whether species showing geographic variation in habitat preference are habitat specialists or simply habitat generalists with varying responses to habitat structure

Transactions of the North American Wildlife and Na↗

USGS2026

A new inventory and conservation assessment of United States islands

To support conservation-focused research and management we developed a new 30-m resolution polygon data layer of the nonlacustrine and nonriverine islands of the United States, with associated attributes describing key physical and conservation geography characteristics. Islands were grouped into a three-tiered hierarchy of island regions (twelve), island provinces (twenty-eight), and individual islands (19,023). Islands were classified as either continental or oceanic based on their physiographic position relative to the North America continental shelf, and estuarine versus nonestuarine depending on their location within or external to estuaries. For each island we assessed the diversity of terrestrial and coastal ecosystems, the number of threatened and endangered (T&E) species listed under the Endangered Species Act, the number of T&E species critical habitats, the number of migratory bird species listed under the Migratory Bird Treaty Act, the number of Key Biodiversity Areas, and the number of and management responsibility for protected areas. We conclude that the conservation importance of islands is disproportionate to their total area as, for example, islands contain 52 percent of the T&E species yet their total area is only 2 percent of the area of the continental mainland. Similarly, of the global total of 431 World Terrestrial Ecosystems, 201 (47 percent) occur on U.S. islands compared with 286 (66 percent) that occur on the U.S. continental mainland.

Annals of the American Association of Geographers↗

USGS2023

Turkey Vulture survival is reduced in areas of greater road density

The demography of, and factors that influence these metrics, are largely unknown for most vultures in the Americas. Survivorship of Turkey Vultures ( Cathartes aura ) may be influenced by landscape heterogeneity and human disturbance. We quantified the effects of landscape composition (Shannon’s diversity index) and configuration (contagion, edge density, and largest patch index), and human disturbance (road density) on the annual and seasonal survival probabilities of the three North American breeding populations (western, central, and eastern) of Turkey Vultures that spend the nonbreeding season in the southeastern portion of the Nearctic and the northern Neotropics during a 17-year period. We used Cox’s proportional hazards models with time-varying covariates to estimate spatial and temporal changes in survival rates of adult Turkey Vultures. Road density, but not landscape composition or configuration, influenced survival rates in space and time. Overall annual survival averaged 0.87 (95% confidence interval [CI]: 0.74–0.98). Mortality risk was low in western and central populations (hazard ratio < 1) but was 3.7 times greater for vultures in the eastern population. Survival during the breeding (0.97, 95% CI: 0.96–0.98) and outbound migration (1.0, 95% CI: 1–1) seasons was significantly higher than the other seasons. Average survival tended to be higher for nonbreeding (0.81, 95% CI: 0.71–0.88) compared to return migration (0.69, 95% CI: 0.56–0.81) seasons. The risk of mortality for all vulture populations increased with road density, and this was greater during the nonbreeding and return migration seasons. The spatial variation in road density across the Americas may generate a network of ecological traps for Turkey Vultures induced to stop in areas of greater road-kill abundance. Road-killed animals acting as an attractant for vultures can increase the occurrence of vulture–vehicle collisions and potentially aggravate human–wildlife conflicts. Further analyses are needed to address survivorship and mortality factors for young birds. Our results may help the implementation of specific mitigation efforts to reduce human–vulture conflicts and vulture mortality. For instance, concentrating efforts to remove road-killed animals in areas where road density is highest can likely reduce vulture–vehicle collisions and associated mortalities of these birds.

Article↗

USGS2015

Changes in thyroid parameters of hatchling American kestrels ( Falco sparverius ) following embryonic exposure to technical short chain chlorinated paraffins (SCCPs; C 10-13 , 55.5% CL)

Chlorinated paraffins (CPs) are complex mixtures of polychlorinated n-alkanes categorized according to their carbon chain length: short chain (SCCPs, C10 – C13), medium (C14 - C17), and long chain (C>17), chlorinated paraffins. SCCPs are primarily used in metalworking applications, as flame retardants, and in paints, adhesives, sealants, textiles, plastics and rubber (UNEP 2012). In 2012, the United Nations Environment Program (UNEP 2012) reported in the Revised Draft Risk Profile for SCCPs, that CPs were produced in the United States, the European Union (EU), Slovakia, Brazil, India, Japan and China. While annual global consumption of SCCPs is large (>25 tonnes/year), it has sharply declined over the past 20 years. SCCPs are released through wastewater, landfills, and air emissions (UNEP 2012). Concentrations of SCCPs have been reported in fish and marine mammals in North and South America, Europe, Japan, Greenland and the Arctic (UNEP 2012 and references therein). Characterization of SCCP concentrations and exposure in terrestrial wildlife is limited. In 2010, SCCP concentrations were reported in the eggs of yellow-legged gulls (Larus michahellis) (4536 ± 40 pg/g wet weight (ww)) and Audouin’s gulls (Larus audouinii) (6364 ± 20 pg/g ww) in Spain (Morales et al. 2012), and little auks (Alle alle) (5 - 88 ng/g ww) and kittiwakes (Rissa tridactyla) (5 - 44 ng/g ww) in the European Arctic (Reth et al. 2006). In Sweden, muscle of ospreys contained CPs of unspecified chain length (Jansson et al. 1993). Although the toxicity of SCCPs has been demonstrated in aquatic invertebrates, fish, frogs, and laboratory rats, there are limited avian studies and these reported no effects of SCCPs on egg parameters of domestic hens (Gallus gallus domesticus) and ducks (Anas platyrhynchos) (UNEP 2012). Despite reported accumulation of SCCPs in wild birds, to our knowledge, exposure-related toxicities and effects with respect to avian wildlife remain unknown.

Organohalogen Compounds↗

USGS2008

Organochlorine pesticide, polychlorinated biphenyl, trace element and metal residues in bird eggs from Salton Sea, California, 2004

The Salton Sea is a highly eutrophic, hypersaline terminal lake that receives inflows primarily from agricultural drainages in the Imperial and Coachella valleys. Impending reductions in water inflow at Salton Sea may concentrate existing contaminants which have been a concern for many years, and result in higher exposure to birds. Thus, waterbird eggs were collected and analyzed in 2004 and compared with residue concentrations from earlier years; these data provide a base for future comparisons. Eggs from four waterbird species (black-crowned night-heron [Nycticorax nycticorax], great egret [Ardea alba], black-necked stilt [Himantopus mexicanus], and American avocet [Recurvirostra Americana]) were collected. Eggs were analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), metals, and trace elements, with current results compared to those reported for eggs collected from the same species and others during 1985a??1993. The two contaminants of primary concern were p,pa??-DDE (DDE) and selenium. DDE concentrations in night-heron and great egret eggs collected from the northwest corner of Salton Sea (Whitewater River delta) decreased 91 and 95%, respectively, by 2004, with a concomitant increase in eggshell thickness for both species. Decreases in bird egg DDE levels paralleled those in tissues of tilapia (Oreochromis mossambicus ?? O. urolepis), an important prey species for herons and egrets. Despite most nests of night-herons and great egrets failing in 2004 due to predation, predicted reproductive effects based on DDE concentrations in eggs were low or negligible for these species. The 2004 DDE findings were in dramatic contrast to those in the past decade, and included an 81% decrease in black-necked stilt eggs, although concentrations were lower historically than those reported in night-herons and egrets. Selenium concentrations in black-necked stilt eggs from the southeast corner of Salton Sea (Davis Road) were similar in 1993 and 2004, with 4.5a??7.6% of the clutches estimated to be selenium impaired during both time periods. Because of present selenium concentrations and future reduced water inflow, the stilt population is of special concern. Between 1992 and 1993 and 2004 selenium in night-heron and great egret eggs from the Whitewater River delta at the north end of the Sea decreased by 81 and 55%, respectively. None of the night-heron or egret eggs collected in 2004 contained selenium concentrations above the lowest reported effect concentration (6.0 I?g/g dw). Reasons for selenium decreases in night-heron and egret eggs are unknown. Other contaminants evaluated in 2004 were all below known effect concentrations. However, in spite of generally low contaminant levels in 2004, the nesting populations of night-herons and great egrets at Salton Sea were greatly reduced from earlier years and snowy egrets (Egretta thula) were not found nesting. Other factors that include predation, reduced water level, diminished roost and nest sites, increased salinity, eutrophication, and reduced fish populations can certainly influence avian populations. Future monitoring, to validate predicted responses by birds, other organisms, and contaminant loadings associated with reduced water inflows, together with adaptive management should be the operational framework at the Salton Sea.

Hydrobiologia↗

USGS2011

Ducks and passerines nesting in northern mixed-grass prairie treated with fire

Prescribed fire is an important, ecology-driven tool for restoration of grassland systems. However, prescribed fire remains controversial for some grassland managers because of reported reductions in bird use of recently burned grasslands. Few studies have evaluated effects of fire on grassland bird populations in the northern mixed-grass prairie region. Fewer studies yet have examined the influence of fire on nest density or survival. In our review, we found no studies that simultaneously examined effects of fire on duck and passerine nesting. During 1998—2003, we examined effects of prescribed fire on the density of upland-nesting ducks and passerines nesting in north-central North Dakota, USA. Apparent nest densities of gadwall ( Anas strepera ), mallard ( A. platyrhynchos ), and all duck species combined, were influenced by fire history of study units, although the degree of influence was not compelling. Fire history was not related to nest densities of blue-winged teal ( A. discors ), northern shoveler ( A. clypeata ), or northern pintail ( A. acuta ); however, apparent nest densities in relation to the number of postfire growing seasons exhibited a strikingly similar pattern among all duck species. When compared to ducks, fire history strongly influenced apparent nest densities of clay-colored sparrow ( Spizella pallida ), Savannah sparrow ( Passerculus sandwichensis ), and bobolink ( Dolichonyx oryzivorus ). For most species examined, apparent nest densities were lowest in recently burned units, increased during the second postfire growing season, and stabilized or, in some cases, decreased thereafter. Prescribed fire is critical for restoring the ecology of northern mixed-grass prairies and our findings indicate that reductions in nest densities are limited mostly to the first growing season after fire. Our results support the premise that upland-nesting ducks and several grassland passerine species are adapted to periodic fires occurring at a frequency similar to that of pre-Euro-American settlement of the region.

North Dakota↗

USGS2004

Nesting ecology of waterbirds at Grays Lake, Idaho

Montane wetlands provide valuable habitat for nesting waterfowl and other waterbirds in the western United States, but relatively little information is available about the nesting ecology of their waterbird communities. We describe the general nesting ecology of breeding waterbirds at a large, shallow montane wetland in southeast Idaho during 1997-2000. Habitats included upland grasslands and intermittently to semipermanently flooded wetland habitats. We located a total of 1207 nests of 23 bird species: eared grebe (Podiceps nigricollis), Canada goose (Branta canadensis), mallard (Anas platyrhynchos), gadwall (A. strepera), American wigeon (A. americana), green-winged teal (A. crecca), blue-winged teal (A. discors), cinnamon teal (A. cyanoptera), northern shoveler (A. clypeata), northern pintail (A. acuta), redhead (Aythya americana), canvasback (A. valisineria), lesser scaup (A. affinis), ruddy duck (Oxyuris jamaicensis), northern harrier (Circus cyaneus), American coot (Fulica americana), Virginia rail (Rallus limicola), greater sandhill crane (Grus canadensis tabida), American avocet (Recurvirostra americana), long-billed curlew (Numenius americanus), Wilsons snipe (Gallinago delicta), Wilsons phalarope (Phalaropus tricolor), and short-eared owl (Asio flammeus). Most nests were initiated in May-early June and were terminated (hatched or destroyed) by the third week of June. Mean daily survival rate (DSR) for Canada goose nests was 0.954 0.005 (SE) (n = 127 nests), equivalent to Mayfield nest success of 21%. Mean DSR for dabbling duck nests over all four years was 0.938 0.006 (n = 141), equivalent to Mayfield nest success of 11%. For all other species where we found >10 nests each year (eared grebe, redhead, canvasback, coot, sandhill crane, American avocet, and Wilsons snipe), >50% of nests found hatched at least one young. Success rates for geese, cranes, and ducks were lower than reported for Grays Lake during 1949-1951 and lower than most other wetlands in the region.

Western North American Naturalist↗

USGS1973

Selective predation by mink, Mustela vison, on waterfowl

Predation by mink ( Mustela vison ) on three types of ducks (captive, pen-reared-released and wild) was documented in two studies at the Northern Prairie Wildlife Research Center, Jamestown, North Dakota. In the first study, 36 of 60 flightless adult and juvenile ducks held on eight 0.1-acre experimental ponds disappeared between 10 July and 4 August 1969. Available evidence indicated that all were killed by a large adult mink. The mink selected recently released incubator-hatched ducklings, females in the process of incubating, and adults and juveniles on a marginal food supply.In the second study, 152 wood duck ducklings ( Aix sponsa ) were released on a 76-acre marsh during 1971. Half of the ducklings, when 24 to 27 days old, were placed at weekly intervals in four floating pens and allowed to escape after 4 days. Each time birds were placed in the floating pens, a comparable group was placed in a predator-proof shoreline pen. Birds in the shoreline pen escaped as they learned to fly when approximately 60 days old. The shoreline of the marsh was periodically searched, and the remains of 21 (28%) of the floating-pen birds were identified in food remains found at 16 mink dens. No remains of birds from the shoreline pen were found at the dens. Coots ( Fulica americana ) were also taken commonly. Wild ducklings appeared to have been almost totally consumed, but the legs and feet of the wood ducks were often left uneaten because of bands and tags.

American Midland Naturalist↗

USGS2020

Evaluation of survey methods for colonial waterbirds at Chase Lake National Wildlife Refuge, North Dakota

Estimating the number of breeding pairs in a mixed-species waterbird colony is difficult because colonial waterbirds are vulnerable to human intrusion and their colonies are often in remote areas with limited access. We investigated methods to estimate the number of nests of waterbirds at a large, mixed-species colony at Chase Lake National Wildlife Refuge in south-central North Dakota. The primary goals of this study were to evaluate survey methods for shrub- and ground-nesting colonial waterbirds at Chase Lake National Wildlife Refuge and to develop protocols for estimating abundance of the different species. The specific objectives were (1) to assess visible-nest counts for ciconiiform species from the perimeter of nesting areas (hereafter, perimeter counts) and observational surveys from fixed points outside the colony to count flights of adult ciconiiforms in and out of the colony (hereafter, flightline surveys) as alternatives to within-colony counts of ciconiiform nests, and (2) to assess semiautomated, pixel-based image-analysis techniques to estimate abundance of American White Pelicans ( Pelecanus erythrorhynchos ) as an alternative to traditional manual counts from aerial photographs. For shrub-nesting ciconiiform species, observers counted 2,259 and 1,759 active ciconiiform nests in 2012 and 2013, respectively, during within-colony counts of ciconiiform nests. Results from within-colony counts of ciconiiform nests indicated a positive relation between the number of nests and the area of the shrub subcolony for the three most common ciconiiform species and all ciconiiform species combined. The perimeter nest counts of ciconiiform nests at Chase Lake represented only 18.8 percent of the total active ciconiiform nests counted in 11 subcolonies in 2012, which was well below the recommended target of 50 percent. Although we found a positive relationship between the number of nests counted during perimeter counts and the number of nests counted during within-colony counts for the three most common ciconiiform species and all ciconiiform species combined, perimeter counts at Chase Lake were hampered by disturbance to nesting birds. Thus, we discontinued the perimeter counts before they were completed. We did not develop predictive models from these perimeter counts in 2012 because these models could be misleading due to inconsistent application of the survey methods, which likely would have provided inaccurate perimeter counts. The extent of this issue is unknown. Flightline surveys at Chase Lake documented patterns of ciconiiform activity that were unknown for this region. For the common ciconiiform species, the number of flights to and from the South Island at Chase Lake were greatest in the morning (7:00−12:00 central daylight time [CDT]) and least in the afternoon (12:00−17:00), and least early in the breeding season (May 29–June 20, 2013) and greatest later in the breeding season (June 24–August 1, 2013). Flightline surveys are an index but lacked comparability with within-colony nest counts because the two methods provide measures of different things (that is, adult activity away from the colony as compared to the number of nests within the colony). The overall proportions of flights generally reflected the proportions of the within-colony nest counts for the four most common species: Black-crowned Night-Heron ( Nycticorax nycticorax ), Cattle Egret ( Bubulcus ibis ), Great Egret ( Ardea alba ), and Snowy Egret ( Egretta thula ). Flightline surveys at Chase Lake indicated apparent variation related to the time of day and season, as well as a variation in detection of inbound and outbound adult ciconiiforms. For ciconiiforms at Chase Lake, the most appropriate combination of survey approaches will depend on the need for annual estimates of nest abundance of ciconiiform species, balanced with the financial, personnel, and logistical constraints associated with the survey methods. For ground-nesting American White Pelicans, the results from this study indicated that digital-image processing using remote-sensing software provides an accurate estimate of the number of American White Pelican nests. Estimates of the number of pelican nests from digital-image processing, using two commercially available remote-sensing software packages, produced nest estimates that were comparable to those of traditional manual counts from aerial photographs.

North Dakota↗