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At least 649 records · Page 36Linked to original sources
USGS2017

Birds choose long-term partners years before breeding

Pair bonds can provide social benefits to long-term monogamous species alongside their benefits for reproduction. However, little is known about when these bonds form, in particular how long they are present before breeding. Previous studies of pair formation in long-term monogamous birds have been rather data-limited, but for many migratory birds they report pair formation on the wintering grounds. We provide the first systematic investigation of prebreeding association patterns of long-term monogamous pairs by examining entire life histories based on tracking data of migratory whooping cranes, Grus americana. We found that a substantial portion (62%) of breeding pairs started associating at least 12 months before first breeding, with 16 of 58 breeding pairs beginning to associate over 2 years before first breeding. For most pairs, these associations with future breeding partners also became unique and distinguishable from association patterns with nonpartner individuals 12 months before first breeding. In addition, 60% of pair associations began before at least one partner had reached nominal sexual maturity. Most pairs began associating in the late spring upon arrival at the summer grounds, while associations beginning at other times of the year were rare. Patterns in the associations of pairs prior to breeding can point to the potential benefits of prebreeding relationships, for instance providing support in competitive interactions or increasing partner familiarity.

Animal Behaviour↗
USGS2018

Evidence for a duplicated mitochondrial region in Audubon’s shearwater based on MinION sequencing

Mitochondrial genetic markers have been extensively used to study the phylogenetics and phylogeography of many birds, including seabirds of the order Procellariiformes. Evidence suggests that part of the mitochondrial genome of Procellariiformes, especially albatrosses, is duplicated, but no DNA fragment covering the entire duplication has been sequenced. We sequenced the complete mitochondrial genome of a non-albatross species of Procellariiformes, Puffinus lherminieri (Audubon’s shearwater) using the long-read MinION (ONT) technology. Two mitogenomes were assembled from the same individual, differing by 52 SNPs and in length. The shorter was 19 kb long while the longer was 21 kb, due to the presence of two identical copies of nad6 , three tRNA, and two dissimilar copies of the control region (CR). Contrary to albatrosses, cob was not duplicated. We further detected a complex repeated region of undetermined length between the CR and 12S. Long-read sequencing suggests heteroplasmy and a novel arrangement within the duplicated region, indicating a complex evolution of the mitogenome in Procellariiformes.

Mitochondrial DNA Part A↗
USGS2019

Perspectives and challenges for the use of radar in biological conservation

Radar is at the forefront for the study of broad‐scale aerial movements of birds, bats and insects and related issues in biological conservation. Radar techniques are especially useful for investigating species which fly at high altitudes, in darkness, or which are too small for applying electronic tags. Here, we present an overview of radar applications in biological conservation and highlight its future possibilities. Depending on the type of radar, information can be gathered on local‐ to continental‐scale movements of airborne organisms and their behaviour. Such data can quantify flyway usage, biomass and nutrient transport (bioflow), population sizes, dynamics and distributions, times and dimensions of movements, areas and times of mass emergence and swarming, habitat use and activity ranges. Radar also captures behavioural responses to anthropogenic disturbances, artificial light and man‐made structures. Weather surveillance and other long‐range radar networks allow spatially broad overviews of important stopover areas, songbird mass roosts and emergences from bat caves. Mobile radars, including repurposed marine radars and commercially dedicated ‘bird radars’, offer the ability to track and monitor the local movements of individuals or groups of flying animals. Harmonic radar techniques have been used for tracking short‐range movements of insects and other small animals of conservation interest. However, a major challenge in aeroecology is determining the taxonomic identity of the targets, which often requires ancillary data obtained from other methods. Radar data have become a global source of information on ecosystem structure, composition, services and function and will play an increasing role in the monitoring and conservation of flying animals and threatened habitats worldwide.

Ecography↗
USGS2021

Highly pathogenic avian influenza virus H5N2 (Clade 2.3.4.4) challenge of mallards age appropriate to the 2015 midwestern poultry outbreak

Background The 2015 highly pathogenic avian influenza virus (HPAIV) H5N2 clade 2.3.4.4 outbreak in upper midwestern U.S. poultry operations was not detected in wild birds to any great degree during the outbreak, despite wild waterfowl being implicated in the introduction, reassortment, and movement of the virus into North America from Asia. This outbreak led to the demise of over 50 million domestic birds and occurred mainly during the northward spring migration of adult avian populations. Objectives There have been no experimental examinations of the pathogenesis, transmission, and population impacts of this virus in adult wild waterfowl with varying exposure histories—the most relevant age class. Methods We captured, housed, and challenged adult wild mallards ( Anas platyrhynchos ) with HPAIV H5N2 clade 2.3.4.4 and measured viral infection, viral excretion, and transmission to other mallards. Results All inoculated birds became infected and excreted moderate amounts of virus, primarily orally, for up to 14 days. Cohoused, uninoculated birds also all became infected. Serological status had no effect on susceptibility. There were no obvious clinical signs of disease, and all birds survived to the end of the study (14 days). Conclusions Based on these results, adult mallards are viable hosts of HPAIV H5N2 regardless of prior exposure history and are capable of transporting the virus over short and long distances. These findings have implications for surveillance efforts. The capture and sampling of wild waterfowl in the spring, when most surveillance programs are not operating, are important to consider in the design of future HPAIV surveillance programs.

Wisconsin↗
USGS2009

Avian response to wildfire in interior Columbia basin shrubsteppe

Wildfire and conversion of sagebrush (Artemisia spp.) shrublands to cheatgrass (Bromus tectorum) grasslands is a serious threat to the shrubsteppe ecosystem, but few studies have documented wildfire's effects on birds with multiple years of pre- and post-fire data. Using data from avian point counts recorded 4 years before and 7 years after a large-scale, severe wildfire in the Columbia Basin of south-central Washington, we found significant effects of fire on population trends or mean abundance of nearly all species investigated. The Sage Sparrow (Amphispiza belli), a sagebrush obligate, was decreasing at a high rate both pre- and post-fire. Among species inhabiting more open shrubsteppe or grasslands, the mean abundance of three (Grasshopper Sparrow, Ammodramus savannarum; Western Meadowlark, Sturnella neglecta; Vesper Sparrow, Pooecetes gramineus) was lower post-fire and one (Lark Sparrow, Chondestes grammacus) showed an initial, but short-lived, increase post-fire before dropping below pre-fire levels. Only one (Horned Lark, Eremophila alpestris) increased steadily post-fire and had higher post-fire mean abundance. ?? 2009 by The Cooper Ornithological Society. All rights reserved.

Condor↗
USGS2010

Space use and habitat selection of migrant and resident American Avocets in San Francisco Bay

San Francisco Bay is a wintering area for shorebirds, including American Avocets (Recurvirostra americana). Recently, a new resident population of avocets has emerged, presumably because of the development of tidal marshes into salt-evaporation ponds. In habitat restoration now underway, as many as 90% of salt ponds will be restored to tidal marsh. However, it is unknown if wintering and resident avocets coexist and if their requirements for space and habitat differ, necessitating different management for their populations to be maintained during restoration. We captured and radio-marked wintering avocets at a salt pond and a tidal flat to determine their population status (migrant or resident) and examine their space use and habitat selection. Of the radio-marked avocets, 79% were migrants and 21% were residents. At the salt pond, residents' fidelity to their location of capture was higher, and residents moved less than did migrants from the same site. Conversely, on the tidal flat, fidelity of residents to their site of capture was lower, and residents' home ranges were larger than those of migrants from the same site. Habitat selection of migrants and residents differed little; however, capture site influenced habitat selection far more than the birds' status as migrants or residents. Our study suggests that individual avocets have high site fidelity while wintering in San Francisco Bay, although the avocet as a species is plastic in its space use and habitat selection. This plasticity may allow wintering migrant and resident avocets to adapt to habitat change in San Francisco Bay. ?? The Cooper Ornithological Society 2010.

Condor↗
USGS2021

Foraging movements and colony attendance of Least Terns (Sternula antillarum) on the central Platte River, Nebraska, USA

Least Terns ( Sternula antillarum ) are known to forage away from nesting colonies, yet little information is available about movement rates and distances. We used VHF transmitters and a network of datalogging receivers to monitor movements of 23 Least Terns on the central Platte River, Nebraska, USA. We typically detected incubating and brood-rearing birds within 8 km of colonies during daylight hours, and up to 17.5 km away at night. Movement distances were even longer during post-fledging (up to 20 km) and nonbreeding (up to 31 km) periods. Colony attendance differed notably by reproductive stage, being highest for incubating and lowest for post-fledging birds. Birds were most frequently detected on the study area during brood-rearing and nonbreeding periods, and most likely to go undetected during incubation and after fledging a brood. Frequency and success of foraging behaviors were lowest on sandpit sites, intermediate on riverine sites, and highest at the Kearney Diversion Dam on the Platte River, where flow patterns likely enhanced forage fish availability. Foraging movements of Least Terns were temporally and spatially variable, with time of day, reproductive stage, and availability of prey hotspots appearing to be key factors. Management of habitat complexes for breeding Least Terns may benefit from emphasizing the availability of profitable foraging habitat within 8 km of nesting areas, and considering foraging habitat within 8 - 30 km as available.

Nebraska↗
USGS2010

Diets of introduced predators using stable isotopes and stomach contents

In a study of predation on ground-nesting birds at South San Francisco Bay (South Bay), California, USA, we analyzed stomach contents and stable isotopes of carbon and nitrogen to identify commonly consumed prey. We obtained the stomach contents from 206 nonnative red foxes (Vulpes vulpes regalis) collected in the South Bay area and Monterey County during 1995-2001 and from 68 feral cats (Felis silvestris) from the South Bay area during 2001-2002. We determined prey identity, biomass, and frequency, described seasonal diet trends, and derived an Index of Relative Importance. Avian species were the most frequent prey we found in the stomachs of red foxes from South Bay (61%), whereas small rodents were most frequent for red foxes from Monterey County (62%). Small rodents were the most frequent prey we found in feral cats (63%). Carbon and nitrogen isotopic signatures for foxes supported stomach content findings. However, isotope results indicated that cats received a majority of their energy from a source other than rodents and outside the natural system, which differed from the stomach content analysis. We demonstrated the utility of both stable isotope and stomach content analyses to establish a more complete understanding of predators' diets. This information aids natural resource managers in planning and evaluating future predator-removal programs and increases our understanding of the impacts of nonnative foxes and cats on native species.

Journal of Wildlife Management↗
USGS2000

Effects of forest management on density, survival, and population growth of wood thrushes

Loss and alteration of breeding habitat have been proposed as causes of declines in several Neotropical migrant bird populations. We conducted a 4-year study to determine the effects of winter prescribed burning and forest thinning on breeding wood thrush ( Hylocichla mustelina ) populations at the Piedmont National Wildlife Refuge (PNWR) in Georgia. We estimated density, adult and juvenile survival rates, and apparent annual survival using transect surveys, radiotelemetry, and mist netting. Burning and thinning did not cause lower densities ( P = 0.25); wood thrush density ranged from 0.15 to 1.30 pairs/10 ha. No radiomarked male wood thrushes ( n = 68) died during the 4 years, but female ( n = 63) weekly survival was 0.981 ± 0.014 (SE) for females ( n = 63) and 0.976 ± 0.010 for juveniles ( n = 38). Apparent annual adult survival was 0.579 (SE = 0.173). Thinning and prescribed burning did not reduce adult or juvenile survival during the breeding season or apparent annual adult survival. Annual population growth (lambda) at PNWR was 1.00 (95% confidence interval = 0.32-1.63), and the considerable uncertainty in this prediction underscores the need for long term monitoring to effectively manage Neotropical migrants. Population growth increased on experimental compartments after the burn and thin (95% CI before = 0.91-0.97, after = 0.98-1.05), while control compartment declined (before = 0.98-1.05, after = 0.87-0.92). We found no evidence that the current management regime at PNWR, designed to improve red-cockaded woodpecker ( Picoides borealis ) habitat, negatively affected wood thrushes.

Georgia↗
USGS1958

Growth and development of the king rail

Growth and development of the King Rail ( Rallus elegans ) from hatching to first flight were studied by observations and measurements of captive birds and by observations of natural nests in the field. This is the fourth in a series of reports on the life history of the King Rail (Meanley 1953, 1956, and 1957). Information in this paper is intended to supplement the data of Bent (1925) on growth and development and the description of juvenal plumage given by Friedmann (1941).

The Auk↗
USGS1999

Harlequin Duck recovery from the Exxon Valdez oil spill: A population genetics perspective

Concerns about Harlequin Duck ( Histrionicus histrionicus ) population recovery following the Exxon Valdez oil spill led biologists to ask whether birds located in different molting and wintering areas belong to genetically distinct and, thus, demographically independent populations. Owing to the lack of direct observations of movements among marine areas, three classes of genetic markers that differed in mode of inheritance were used to evaluate the degree of genetic differentiation among wintering areas within Prince William Sound (PWS) and the Alaska Peninsula and Kodiak Archipelago (APKA). We could not reject the null hypothesis that the wintering aggregations within each region are composed of a single genetically panmictic population. Differences in genotype frequencies among wintering locations within PWS and APKA were low and nonsignificant for all three classes of markers. Furthermore, we saw no evidence for deviations in Hardy-Weinberg equilibrium or gametic disequilibrium between loci within a winter collection site as would be expected if these locales were composed of individuals from reproductively isolated (and genetically distinct) breeding locales. Finally, no evidence for significant structuring was noted between PWS and APKA. Lack of spatial genetic structuring could be due to the cumulative effects of low levels of gene flow over long time periods, low levels of gene flow by immature birds moving between marine habitats, or to episodic dispersal caused by habitat alteration (e.g. volcanic eruptions). Harlequin Ducks are likely to recolonize or enhance populations in areas recovering from environmental damage via emigration of birds from non-affected areas. Demographic studies suggest, however, that levels of movements are low, and that population recovery by emigration is a long-term process.

The Auk↗
USGS2015

Quantifying and predicting fuels and the effects of reduction treatments along successional and invasion gradients in sagebrush habitats

Sagebrush shrubland ecosystems in the Great Basin are prime examples of how altered successional trajectories can create dynamic fuel conditions and, thus, increase uncertainty about fire risk and behavior. Although fire is a natural disturbance in sagebrush, post-fire environments are highly susceptible to conversion to an invasive grass-fire regime (often referred to as a “grass-fire cycle”). After fire, native shrub-steppe plants are often slow to regenerate, whereas nonnative annuals, especially cheatgrass (Bromus tectorum) and medusahead (Taeniatherum caput-medusae), can establish quickly and outcompete native species. Once fire-prone annuals become established, fire occurrences increase, further promoting dominance of nonnative species. The invasive grass-fire regime also alters nutrient and hydrologic cycles, pushing ecosystems beyond ecological thresholds toward steady-state, fire-prone, nonnative communities. These changes affect millions of hectares in the Great Basin and increase fire risk, decrease habitat quality and biodiversity, accelerate soil erosion, and degrade rangeland resources for livestock production. In many sagebrush landscapes, constantly changing plant communities and fuel conditions hinder attempts by land managers to predict and control fire behavior, restore native communities, and provide ecosystem services (e.g., forage production for livestock). We investigated successional and nonnative plant invasion states and associated fuel loads in degraded sagebrush habitat in a focal study area, the Morley Nelson Snake River Birds of Prey National Conservation Area (hereafter the NCA), in the Snake River Plain Ecoregion of southern Idaho. We expanded our inference by comparing our findings to similar data collected throughout seven major land resource areas (MLRAs) across the Great Basin (JFSP Project “Fire Rehabilitation Effectiveness: A Chronosequence Approach for the Great Basin” [09-S-02-1]). 4 We used a combination of field-sampling, experimental treatments, and remotely sensed data to address the following questions: (1) How do fuel loads change along gradients of succession and invasion in sagebrush ecological sites? (2) How do fuel reduction treatments influence fuels in invaded areas formerly dominated by sagebrush? (3) How do fuel loads vary across landscapes and which remote sensing techniques are effective for characterizing them?

Idaho↗
USGS2017

Integrated wetland management for waterfowl and shorebirds at Mattamuskeet National Wildlife Refuge, North Carolina

Mattamuskeet National Wildlife Refuge (MNWR) offers a mix of open water, marsh, forest, and cropland habitats on 20,307 hectares in coastal North Carolina. In 1934, Federal legislation (Executive Order 6924) established MNWR to benefit wintering waterfowl and other migratory bird species. On an annual basis, the refuge staff decide how to manage 14 impoundments to benefit not only waterfowl during the nonbreeding season, but also shorebirds during fall and spring migration. In making these decisions, the challenge is to select a portfolio, or collection, of management actions for the impoundments that optimizes use by the three groups of birds while respecting budget constraints. In this study, a decision support tool was developed for these annual management decisions. Within the decision framework, there are three different management objectives: shorebird-use days during fall and spring migrations, and waterfowl-use days during the nonbreeding season. Sixteen potential management actions were identified for impoundments; each action represents a combination of hydroperiod and vegetation manipulation. Example hydroperiods include semi-permanent and seasonal drawdowns, and vegetation manipulations include mechanical-chemical treatment, burning, disking, and no action. Expert elicitation was used to build a Bayesian Belief Network (BBN) model that predicts shorebird- and waterfowl-use days for each potential management action. The BBN was parameterized for a representative impoundment, MI-9, and predictions were re-scaled for this impoundment to predict outcomes at other impoundments on the basis of size. Parameter estimates in the BBN model can be updated using observations from ongoing monitoring that is part of the Integrated Waterbird Management and Monitoring (IWMM) program. The optimal portfolio of management actions depends on the importance, that is, weights, assigned to the three objectives, as well as the budget. Five scenarios with a variety of objective weights and budgets were developed. Given the large number of possible portfolios (16 14 ), a heuristic genetic algorithm was used to identify a management action portfolio that maximized use-day objectives while respecting budget constraints. The genetic algorithm identified a portfolio of management actions for each of the five scenarios, enabling refuge staff to explore the sensitivity of their management decisions to objective weights and budget constraints. The decision framework developed here provides a transparent, defensible, and testable foundation for decision making at MNWR. The BBN model explicitly structures and parameterizes a mental model previously used by an expert to assign management actions to the impoundments. With ongoing IWMM monitoring, predictions from the model can be tested, and model parameters updated, to reflect empirical observations. This framework is intended to be a living document that can be updated to reflect changes in the decision context (for example, new objectives or constraints, or new models to compete with the current BBN model). Rather than a mandate to refuge staff, this framework is intended to be a decision support tool; tool outputs can become part of the deliberations of refuge staff when making difficult management decisions for multiple objectives.

North Carolina↗
USGS1980

Secondary poisoning of owls by anticoagulant rodenticides

Anticoagulants-compounds that prevent clotting of the blood-are extensively used for control of small mammal pests. The potential secondary hazards of 6 anticoagulant rodenticides to birds of prey were examined in this study. Whole rats or mice were killed with each anticoagulant and were fed to 1-3 species of owls. Owls died of hemorrhaging after feeding on rats killed with bromadiolone, brodifacoum, or diphacinone; sublethal hemorrhaging occurred in owls fed rats killed with difenacoum. These results demonstrate potential secondary hazards of 4 anticoagulants to avian predators. No abnormalities were observed in owls fed rats killed with fumarin and chlorophacinone

Wildlife Society Bulletin↗
USGS1998

Breeding-season food habits of burrowing owls (Athene cunicularia) in southwestern Dominican Republic

Diet data from 20 Burrowing Owl (Athene cunicularia) nests were collected in southwestern Dominican Republic in 1976, 1982, and 1996. Invertebrates (53.3%) comprised the most numerous prey items (N = 396) delivered to nests by adult owls, but vertebrates (46.7%) were much better represented than in other studies of Burrowing Owl diet. Among vertebrates, birds (28.3% of all items) and reptiles (14.9%) were most important, whereas mammals (1.0%) and amphibians (2.5%) were less commonly delivered to nests. Vertebrates, however, comprised more than twice (69.2%) of the total biomass as invertebrates (30.8%), with birds (50.4%) and reptiles (12.8%) the most important of the vertebrate prey classes. A positive relationship was observed between bird species abundance and number of individuals taken as prey by Burrowing Owls.

Journal of Raptor Research↗
USGS2003

Invertebrate response to snow goose herbivory on moist-soil vegetation

Foraging activity by snow geese (Chen caerulescens) often creates large areas devoid of vegetation ("eat-outs") in moist-soil impoundments and coastal wetlands. Open-water habitats that result from eat-outs may be valuable foraging areas for other wetland-dependent birds (i.e., waterfowl and shorebirds). However, few studies have examined the effects of goose-induced habitat changes on invertebrates, an important food source for both waterfowl and shorebirds. We quantified changes in abundance and composition of benthic invertebrates in response to snow goose herbivory in moist-soil impoundments at Prime Hook National Wildlife Refuge, Delaware, USA. We found invertebrate taxon richness and diversity and abundance of Chironomidae, Coleoptera, and Total Invertebrates to be higher in goose-excluded sites than in adjacent eat-outs. These effects were most pronounced during January, February, and early April. We also measured invertebrate abundance in shorebird exclosures in eat-outs but found few detectable effects of shorebird predation on invertebrates. Our study demonstrated that abundant snow geese may negatively influence availability of invertebrates for other nonbreeding waterbirds, suggesting that management actions to reduce local goose populations or deter feeding in impoundments may be warranted.

Wetlands↗
USGS2011

Population estimates and monitoring guidelines for endangered Laysan Teal, Anas Laysanensis, at Midway Atoll: Pilot study results 2008-2010.

Accurate estimates of population size are often crucial to determining status and planning recovery of endangered species. The ability to detect trends in survival and population size over time enables conservation managers to make effective decisions for species and refuge management. During 2004–2007, the translocated population of endangered Laysan Teal (Anas laysanensis; also Laysan Duck) was fitted with radio transmitters providing known (―gold standard‖) measures of survival and reproduction. However, as the population grew, statistically rigorous monitoring protocols were needed that were less labor intensive than radio telemetry. A population die-off and alarmingly high number of carcasses (181) were recorded during a botulism epizootic in August–October 2008, which further reinforced the need for effective monitoring protocols since this endangered species is vulnerable to catastrophic population declines. In fall 2008, we initiated a pilot study using standardized surveys with uniquely marked birds to monitor abundance and estimate the population growth rate of the reintroduced Laysan Teal. Since few birds carried marks (leg bands) after the 2008 botulism die-off (only about 15% of the population), and standardized surveys were not yet implemented, the magnitude of the die-off on the population size was unknown. To learn more about this endangered species' status and develop monitoring protocols useful to refuge managers and recovery planners in the U.S. Fish and Wildlife Service (USFWS), we marked (banded) 252 new Laysan Teal for this pilot project. With skilled refuge staff and trained volunteers, we conducted counts of marked, unmarked, and unknown birds during bimonthly surveys from Oct 2008 to Jan 2010. We recorded the identities of marked birds observed, recovered carcasses, and then used the last date a bird was detected alive and the median resight frequency to conclude if a bird was likely to be alive on a given survey date. Using mark-resight data and individual resight frequencies, we produced a series of abundance estimates from surveys that met accuracy criteria and approached ―closed population‖ assumptions. Since only one year of standardized, atoll-wide surveys were conducted, we analyzed data selected from multiple surveys using Lincoln-Petersen (LP) estimates instead of multi-year likelihood estimators. We adjusted surveys to account for unknown birds (e.g., swimming birds), temporary band loss, and described the frequency of double counting. Double counting is an important consideration in the population estimate because we found a maximum of 13% of marked birds were counted multiple times during a survey. These survey protocols allowed us to estimate the species' post-fledging population (combined adults and juveniles), and the methods are comparable to those used on Laysan Island. The Laysan Teal population increased 91% from 247 (95% CI, 233–260) in 2007 to 439–508 in early 2010. There was no change from 2009 to 2010 indicating that there was no population growth, however, our 2010 estimate should be considered preliminary since only one month of 2010 resight data was used. We compared a series of direct counts to their corresponding population estimates during 2008–2009 to evaluate if counts could serve as an unbiased ―index‖ of population abundance. There was a moderate correlation between abundance estimates and total birds counted (r 2 = 0.51) during resight surveys but a low correlation with all-wetland counts (r 2 = 0.02). This indicated that using direct all-wetland counts to predict abundance would result in confidence intervals on the order of ± 200 birds, which is equal to 50% of the estimate. With such large confidence intervals, it would be unlikely to detect annual changes in abundance or determine the magnitude of a catastrophic decline. To improve the Laysan Teal population estimates, we recommend changes to the monitoring protocol. Additional years of data are needed to quantify inter-annual seasonal detection probabilities, which may allow the use of standardized direct counts as an unbiased index of population size. Survey protocols should be enhanced through frequent resights, regular survey intervals, and determining reliable standards to detect catastrophic declines and annual changes in adult abundance. In late 2009 to early 2010, 68% of the population was marked with unique color band combinations. This allowed for potentially accurate adult population estimates and survival estimates without the need to mark new birds in 2010, 2011, and possibly 2012. However, efforts should be made to replace worn or illegible bands so birds can be identified in future surveys. It would be valuable to develop more sophisticated population size and survival models using Program MARK, a state-of-the-art software package which uses likelihood models to analyze mark-recapture data. This would allow for more reliable adult population and survival estimates to compare with the ―source‖ Laysan Teal population on Laysan Island. These models will require additional years of resight data (> 1 year) and, in some cases, an intensive annual effort of marking and recapture. Because data indicate standardized all-wetland counts are a poor index of abundance, monitoring efforts could be improved by expanding resight surveys to include all wetlands, discontinuing the all-wetland counts, and reallocating some of the wetland count effort to collect additional opportunistic resights. Approximately two years of additional bimonthly surveys are needed to validate the direct count as an appropriate index of population abundance. Additional years of individual resight data will allow estimates of adult population size, as specified in recovery criteria, and to track species population dynamics at Midway Atoll.

Technical Report↗
USGS1988

Conservation of North American rallids

The Rallidae are a diverse group in their habitat selection, yet most North American species occur in or near wetlands As a consequence, most species are subject to habitat enhancement or perturbation from waterfowl management programs. The overall effects of these management programs relative to rallid conservation have been assessed for few species, and there is a need for synthesis of such information. In the cases of some species or raves, population status is not known, and suggested directions for conservation and management are needed. Rare, endangered, or status undetermined species or races often occur in areas where related species are classified as game birds, and the effects of such hunting on rarer forms are not known. Their generally secretive nature, the endangered status of several races and populations, and continued loss of habitat and threats to present habitat, warrant an examination of the conservation status of the North American taxa in this group. In 1977, a committee of the International Association of Fish and Wildlife Agencies summarized available information on management and biology of American Coots ( Fulica americana ), rails, and gallinules in North America (Holliman 1977). That summary was intended to provide relatively complete information on conservation of these species, and also to provide guidance for research within the U.S. Fish and Wildlife Service's (FWS) Accelerated Research Program for Webless Migratory Shore and Upland Game Birds (ARP). Subsequently, a number of rallid studies were funded under this program. The program was eliminated in 1982, following substantial research activities on North American rallids. Since the demise of the ARP, additional research on rallids in North America has focused on an area the International Association of Fish and Wildlife Agencies report failed to cover in detail--that of endangered rallids in the U.S. and their possessions. Most of these studies have been of threatened and endangered taxa in western coastal marshes. This report updates and summarizes information on North American rallids since the ARP report and identifies the major conservation problems of this group with the intent of focusing future efforts on these priority issues. Consideration of island forms occurring within U.S. possessions is beyond the scope of this report, mainly because of the special conservation problems associated with their insular distribution. The major topics include habitat requirements, effects of habitat and hunting management techniques currently practiced on wetland areas, and conservation of endangered and threatened populations. Research needs are identified. Habitats of the American Coot are similar to those of several waterfowl species, and the biology of coots is considered only as it is typical of rails in general.

The Wilson Bulletin↗