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At least 1,099 records · Page 61Linked to original sources
USGS1979

Bird communities associated with succession and management of lowland conifer forests

Data from published bird censuses were used to determine changes in avian communities in relation to plant succession, fire, type conversion, and timber management practices in lowland conifer forests in the northeastern United States. With modifications in current logging practices, habitat for the bird species that nest in undisturbed stands can be provided. Management guidelines are recommended.

Book chapter↗
USGS1981

Estimates of avian population trends from the North American Breeding Bird Survey

One of the major purposes of bird population studies is to document changes in population size over a period of years. The traditional method used in Europe and North America to detect population change is to calculate annual ratios. However, this method can produce spurious results when ratios are accumulated over many years. Consequently, new methods of computing trends are needed. Several new methods of estimating population trends are developed and illustrated with data from the North American Breeding Bird Survey (BBS). Each method is compared in terms of its assumptions, biases, and limitations. On the basis of these comparisons we recommend one method that we feel most accurately detects true population trends. Both the biological and statistical justifications for the model selection are presented. Trends estimated with this model are then presented for two species.

Book chapter↗
USGS1986

Aquatic birds and selenium in the San Joaquin Valley

Kesterton Reservoir is a series of ponds comprising 1,200 acres sitting in the grasslands of the Kesterton National Wildlife Refuge. It is bounded on the east by the San Luis Drain, a concrete-lined canal that discharges agricultural drainage into the ponds at their southern end, from which point it then flows northward through the twelve ponds (see the map on the page following). Mike Saki and I studied several of these ponds to determine the concentrations of selenium and other contaminants in food-chain organisms. You'll hear more about this from Mike shortly. My portion of the study was to determine the reproductive success of birds nesting in the ponds and to collect birds so that we could find out what they were eating and what levels of selenium were in their tissues.

California↗
USGS1988

Forest fragmentation and its effects on birds

Fragmentation of forest land, whether by suburban development, highways, transmission lines, or poorly planned cutting regimes, seriously affects reproduction by the large numbers of obligate forest interior birds. Many of our warblers, vireos, thrushes, tanagers, and flycatchers are highly migratory insectivorous birds that spend more than half the year in the neotropics, but migrate north to the United States and Canada to rear their young. These tropical visitors are especially vulnerable to predation and cowbird parasitism and are unable to maintain their populations within 100-200 m of forest edge. Habitats for these declining species can be provided by managing forest lands in large blocks so as to maintain at all times extensive contiguous areas of successional stages as well as of mature forest. Avoiding scattered small cuts will also help by reducing edge, road construction, and other disturbance.

Book chapter↗
USGS1993

Forest to agriculture conversion in southern Belize: Implications for migrant land birds

Central America offers a suite of neotropical habitats vital to overwintering migrant land birds. The recent decline of many forest dwelling avian migrants is believed to be related in part to neotropical deforestation and land use change. However, spatio-temporal trends in neotropical habitat availability and avian migrant habitat use are largely unknown. Such information is needed to assess the impact of agriculture conversion on migrant land birds. In response, the USDI Fish and Wildlife Service and the University of Maine began a cooperative study in 1988 which applies remote sensing and field surveys to determine current habitat availability and avian migrant habitat use. Study sites include areas in Belize, Costa Rica, Guatemala and southern Mexico. Visual assessment of Landsat TM imagery indicates southern Belize forests are fragmented by various agricultural systems. Shifting agriculture is predominant in some areas, while permanent agriculture (citrus and mixed animal crops) is the primary system in others. This poster focuses on efforts to monitor forest to agriculture conversion in southern Belize using remote sensing, field surveys and GIS techniques. Procedures and avian migrant use of habitat are summarized.

Book chapter↗
USGS1990

Wood duck population trends from the North American Breeding Bird Survey

The North American Breeding Bird Survey (BBS) has been conducted yearly since 1966, and can be used to describe relative population density and trends of birds in North America north of Mexico. Wood ducks (Air sponsa) are difficult to survey using conventional waterfowl monitoring techniques, but a large portion of their range is surveyed by the BBS. Wood ducks are detected at low densities on many BBS routes, and population trends can be estimated for most regions. Populations have been increasing throughout North America since 1966, but statistically significant increases generally occurred only in the early (1966-78) part of the period. Roadside survey methodology used in the BBS has limitations that make it inefficient as a survey technique for wood ducks, and we recommend using modified methodologies that specifically survey wood duck habitat.

Book chapter↗
USGS1992

Population models for passerine birds: structure, parameterization, and analysis

Population models have great potential as management tools, as they use infonnation about the life history of a species to summarize estimates of fecundity and survival into a description of population change. Models provide a framework for projecting future populations, determining the effects of management decisions on future population dynamics, evaluating extinction probabilities, and addressing a variety of questions of ecological and evolutionary interest. Even when insufficient information exists to allow complete identification of the model, the modelling procedure is useful because it forces the investigator to consider the life history of the species when determining what parameters should be estimated from field studies and provides a context for evaluating the relative importance of demographic parameters. Models have been little used in the study of the population dynamics of passerine birds because of: (1) widespread misunderstandings of the model structures and parameterizations, (2) a lack of knowledge of life histories of many species, (3) difficulties in obtaining statistically reliable estimates of demographic parameters for most passerine species, and (4) confusion about functional relationships among demographic parameters. As a result, studies of passerine demography are often designed inappropriately and fail to provide essential data. We review appropriate models for passerine bird populations and illustrate their possible uses in evaluating the effects of management or other environmental influences on population dynamics. We identify environmental influences on population dynamics. We identify parameters that must be estimated from field data, briefly review existing statistical methods for obtaining valid estimates, and evaluate the present status of knowledge of these parameters.

Book chapter↗
USGS1995

Delineating bird populations using ring recoveries

We delineate bird populations using cluster analysis to group ringing sites based on pairwise comparisons of recoveries. Clustering provides a quantitative (but non-unique) grouping that can be used to examine the relationships of bird distributions at both local and regional geographic scales. Clustering is based on similarity matrices composed of pairwise comparisons of recovery distributions from ringing sites. We demonstrate the method using mallard (Anas platyrhynchos) ring recoveries to group ringing sites in south-central Canada, and discuss the possibilities for these analyses for non-hunted species with few recoveries.

Book chapter↗
USGS1995

Artificial insemination and cryopreservation of semen from nondomestic birds

Studies of Al and cryopreservation of semen from nondomestic birds began because of the increased emphasis on conservation of avian species threatened with extinction. Over the years, aviculturists have developed techniques for Al and cryopreservation of semen obtained from a variety of birds ranging from passerines to Andean condors. Generally, for each new species, we develop a practical semen collection technique and then evaluate the semen. A commercial semen extender (Beltsville Poultry Semen Extender) is modified and used to dilute the semen and provide support for the sperm during the freezing process (the pH and osmolality of the extender is adjusted to reflect the pH and osmolality of the semen being frozen). We find that the freezing schedule developed by Sexton (1977), which utilizes dimethylsulfoxide (DMS0) as cryoprotectant, works well for many species. We cool the sample sequentially in an ethanol bath, in liquid nitrogen vapor, and lastly in liquid nitrogen. Although we have experimented with a variety of freezing protocols, we prefer a 15-min equilibration period in DMSO at 5 C. We begin the freezing process by cooling at -1 C/min from 5 to -20 C in the ethanol bath. The samples are transferred into a vapor tank at a location just above liquid nitrogen and frozen at -50 C/min to -80 C. To complete the freezing process, the samples are plunged into the liquid nitrogen in the bottom of the vapor tank. The samples remain in liquid nitrogen until they are thawed just before insemination. If necessary, the freezing equipment can be transported in a van to remote locations.

Book chapter↗
USGS1999

Regional analysis of population trajectories from the North American Breeding Bird Survey

The North American Breeding Bird Survey (BBS) was started in 1966, and provides information on population change and distribution for most of the birds in North America. The geographic extent of the survey, and the logistical compromises needed to survey such a large area, present many challenges for estimation from BBS data. In this paper, we describe the survey and discuss some of the limitations of the survey design and implementation. Analysis of the survey has evolved over time as new statistical methods and insights into the analysis of count data are developed. Survey results and analysis tools for the BBS are now available over intemet; we present new methods that use generalized linear models for estimation of population change and empirical Bayes procedures for regional summaries.

Book chapter↗
USGS1993

Species richness and relative abundance of breeding birds in forests of the Mississippi Alluvial Valley

In 1992, the Vicksburg Field Research Station of the National Wetlands Research Center initiated research on the ecology of migratory birds within forests of the Mississippi Alluvial Valley (MAV). The MAV was historically a nearly contiguous bottomland hardwood forest, however, only remnants remain. These remnants are fragmented and often influenced by drainage projects, silviculture, agriculture, and urban development. Our objectives are to assess species richness and relative abundance, and to relate these to the size, quality, and composition of forest stands. Species richness and relative abundance were estimated for 53 randomly selected forest sites using 1 to 8 point counts per site, depending on the size of the forest fragment. However, statistical comparisons among sites will be restricted to an equal number ofpoint counts within the sites being compared. Point counts, lasting five minutes, were conducted from 11 May to 29 June 1992, foltowing Ralph, Sauer, and Droege (Point Count Standards; memo dated 9 March 1992). Vegetation was measured at the first three points on each site using a modification of the methods employed by Martin and Roper (Condor 90: 5 1-57; 1988). During 252 counts, 7 1 species were encountered, but only 62 species were encountered within a 50-m radius of point center. The mean number of species encountered within 50 m of a point, was 7.3 (s.d. = 2.7) and the mean number of individuals was 11.2 (s.d. = 4.2). The mean number of species detected at any distance was 9.6 (s.d, = 2.8) and the mean number of individuals was 15.6 (s.d. = 7.9). The most frequently encountered warblers in the MAV were Prothonotary Warbler and Northern Parula. Rarely encountered warblers were American Redstart and Worm-eating Warbler. The genera, Quercus, Ulmus, Carya, and Celtis were each encountered at 80 or more of the 152 points at which vegetation was sampled. Species most frequentlyencountered were: sugarberry (Celtis laevagata), water hickory (Caqa aquatica), American elm (Ulmus arnericana), sweetgum (Liquidambar styraciflua) and willow oak (Quercus phellos) The mean basal area of all trees 10 cm diameter-at-breast height (dbh) was 28 m2 /ha (range 7-70). The mean canopy cover was 87 percent, mean canopy height was 20 m, ground cover was 60 percent, and vegetation density (2-7 m) was 47 percent. The most frequently encountered understory species were sugarberry, ash (Fraxinus spp.), maple (Acer spp.), and elm (Ulnrus spp.). A cooperative GIs effort among the U.S. Fish and Wildlife Service, the Nature Conservancy, and the University of Arkansas is currently classifying forested habitats within the MAV. This effort will provide information on stand size and topology which will be used in concert with our current data, and data from visits to additional forest stands in 1993, to assess the relationship between the size, quatity, and composition of forests within the MAV and their breeding bird community.

Book chapter↗
USGS2000

Development of management objectives for breeding birds in the Mississippi Alluvial Valley

We used a six-step process to set habitat objectives and population goals for breeding birds in the Mississippi Alluvial Valley. Specifically, we used existing empirical studies and mathematically derived viable population estimates to define habitat objectives and population goals for bottomland hardwood forest, the most important habitat type in this physiographic area. Although habitat objectives must address both quality and quantity, we concentrate here on the size and number of forest patches in this highly fragmented landscape. To support source populations of all forest breeding birds we recommend the protection/restoration of 52 forest patches that are 4,000-8,000 ha in size, 36 patches of 8,000-40,000 ha, and 13 patches greater than 40,000 ha. Although every physiographic area is unique, the methodology applied here should be applicable in other situations.

Book chapter↗
USGS2000

Modeling the distribution of neotropical birds throughout the Americas

I assessed tbe geographic information system (GIS) model and data layers used to create individual Neotropical bird species distribution maps from habitat data contained in the Ecological and Distributional Databases in 'Neotropical Birds: Ecology and Conservation' by D.F. Stotz, J.W. Fitzpatrick, T.A. Parker Ill, and D.K. Moskovits.

Book chapter↗
USGS2005

Population trends of North American sea ducks as revealed by the Christmas Bird Count

Relative to other waterfowl, sea ducks are not well understood, yet evidence from a variety of analyses suggests that as many as 10 of the 15 species of North American sea ducks may be declining in population. However, because of the difficulty of conducting surveys of breeding populations and the lack of range-wide winter surveys, few data are available to assess the population trends of sea ducks with confidence. We analyze Audubon Christmas Bird Count data using hierarchical modeling methods that control for varying effort among circles and over time. These procedures allow us to assess early-winter relative density patterns among states and Bird Conservation Regions (BCRs) while also assessing trends in these regions and across the species North American range. Over the interval 1966 - 2003, continent-wide declines were observed in 1 of 11 species (the White-winged Scoter; -3.7%/yr). We compare CBC results to estimates of population change derived from the midwinter waterfowl survey conducted by the US Fish and Wildlife Service. The CBC does not effectively sample offshore populations of sea ducks; however, the CBC data can be used to assist in development of species-specific surveys, and CBC data can be used in combination with additional offshore sampling programs to better sample sea duck species.

Book chapter↗
USGS2008

Bird response to silviculture induced change in forest structure within bottomland hardwood forests

Silvicultural treatments prescribed to encourage development of desired stand structure (i.e., wildlife-forestry) should result in increased abundance of many bird species of management concern, especially species using dense understory habitat. Desired forest conditions within bottomland vary among sites, but average 60-70% overstory canopy that is heterogeneously distributed with >5 dominant trees/ha retained, and a basal area of 14-16 m2/ha. Desired mid-story and understory cover are between 25-40%. Cavity trees (small and large) as well as dead and/or stressed trees should be retained, ultimately providing >14 m3/ha coarse woody debris, and shade-intolerant tree regeneration should be present on 30-40% of the area. We assessed avian response to prescribed wildlife-forestry silviculture treatments via distance-adjusted point counts and constant effort mist-netting within forest stands on Tensas River National Wildlife Refuge in northeastern Louisiana. More species and individuals were detected within stands 1-13 years post-treatment than within untreated stands. Most species, especially species benefiting from disturbance, increased in density after treatment. A few species decreased in density, yet remained fairly relatively abundant post-treatment. Captures from netting suggested three generalized responses to wildlife-forestry silviculture: (1) species with rapid, short-duration positive response, (2) species with slower but more prolonged positive response, and (3) species which initially declined but had long-term positive population response. We recommend increased use of prescribed wildlife-forestry silvicultural prescriptions to enhance bottomland forest habitat for priority bird species.

Book chapter↗
USGS2009

Inference about species richness and community structure using species-specific occupancy models in the National Swiss Breeding Bird Survey MUB

Species richness is the most widely used biodiversity measure. Virtually always, it cannot be observed but needs to be estimated because some species may be present but remain undetected. This fact is commonly ignored in ecology and management, although it will bias estimates of species richness and related parameters such as occupancy, turnover or extinction rates. We describe a species community modeling strategy based on species-specific models of occurrence, from which estimates of important summaries of community structure, e.g., species richness, occupancy, or measures of similarity among species or sites, are derived by aggregating indicators of occurrence for all species observed in the sample, and for the estimated complement of unobserved species. We use data augmentation for an efficient Bayesian approach to estimation and prediction under this model based on MCMC in WinBUGS. For illustration, we use the Swiss breeding bird survey (MHB) that conducts 2?3 territory-mapping surveys in a systematic sample of 267 1 km2 units on quadrat-specific routes averaging 5.1 km to obtain species-specific estimates of occupancy, and estimates of species richness of all diurnal species free of distorting effects of imperfect detectability. We introduce into our model species-specific covariates relevant to occupancy (elevation, forest cover, route length) and sampling (season, effort). From 1995 to 2004, 185 diurnal breeding bird species were known in Switzerland, and an additional 13 bred 1?3 times since 1900. 134 species were observed during MHB surveys in 254 quadrats surveyed in 2001, and our estimate of 169.9 (95% CI 151?195) therefore appeared sensible. The observed number of species ranged from 4 to 58 (mean 32.8), but with an estimated 0.7?11.2 (mean 2.6) further, unobserved species, the estimated proportion of detected species was 0.48?0.98 (mean 0.91). As is well known, species richness declined at higher elevation and fell above the timberline, and most species showed some preferred elevation. Route length had clear effects on occupancy, suggesting it is a proxy for the size of the effectively sampled area. Detection probability of most species showed clear seasonal patterns and increased with greater survey effort; these are important results for the planning of focused surveys. The main benefit of our model, and its implementation in WinBUGS for which we provide code, is its conceptual simplicity. Species richness is naturally expressed as the sum of occurrences of individual species. Information about species is combined across sites, which yields greater efficiency or may even enable estimation for sites with very few observed species in the first place. At the same time, species detections are clearly segregated into a true state process (occupancy) and an observation process (detection, given occupancy), and covariates can be readily introduced, which provides for efficient introduction of such additional information as well as sharp testing of such relationships.

Book chapter↗
USGS1974

The breeding bird atlas of Montgomery County, Maryland, USA

A two-year Breeding Bird Atlas program for Montgomery County was undertaken by the Maryland Ornithological Society in 1971-1972. The county was divided into 65 5 km blocks and each block was assigned to an observer. Preliminary results show 46 to 93 species (mean 66) recorded per 5 km block and from 10 to 52 species (mean 28) confirmed per block. When the data are combined into 10 km block, the number of species recorded ranges from 74 to 97 (mean 88) and the number of confirmed species ranges from 36 to 62 (mean 49). The organizers underestimated the amount of time that would be required for sufficient coverage, and they plan to extend coverage for a third year in order to provide a much firmer basis for future comparisons. Specific suggestions for improving coverage are listed. The advantages of using as small a grid as possible are stressed, and it is recommended that in future Atlas projects each assigned block be subdivided into quarters for more detailed mapping, and especially to enable future changes in bird distribution to be detected more readily.

Acta Ornithologica↗
USGS2000

Seventeenth breeding-bird census. 34. Diked wet meadow

Several characteristics of plumage, including color and molt schedule, are influenced by hormonal signals, and hence may be modified by endocrine active contaminants. If so, the functions of plumage (e.g. communication for mating or territorial defense), may be compromised by exposure to such compounds. Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental toxins that can disrupt endocrine function in laboratory animals. Captive American kestrels (Falco sparverius) were fed PCBs (Aroclor 1242) at 6 and 60 ppm, thyroxine at 10 ppm, estradiol at 1.4 ppm, and a thyroid hormone blocker (propylthiouracil: PTU) at 2000 ppm, mixed in their normal diet. Plumage characteristics measured included: the width of the black subterminal band on the tail, brightness (a composite index of hue and saturation), reflectance from 230 - 800 nm (measured on a reflectance spectrophotometer), the pattern of feather loss and regrowth on the tail and wing, and the timing of onset and the duration of molt. PCB-treated birds did not differ from controls, but birds treated with thyroxine were significantly different from those dosed with estradiol or PTU in the width of subterminal tail bands, reflectance, and duration of molt. Thus, although hormone treatments did modify some of the plumage characteristics we measured, PCB treatments at these exposure levels did not.

Society of Environmental Toxicology and Chemistry,↗