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At least 991 records · Page 55Linked to original sources

The Conservation Reserve Program: habitat for grassland birds

The Conservation Reserve Program (CRP) has effected major changes to the landscape, especially in the northern Great Plains. Breeding birds have responded dramatically to habitat changes by colonizing CRP fields, often in large numbers. The vegetation in most CRP fields consists of introduced grasses and legumes, along with a variety of weedy species. This paper describes the bird populations found during three years of surveys on more than 300 CRP fields in western Minnesota, North Dakota, South Dakota, and eastern Montana. We relate densities of selected species to geographic location, annual effects, conservation practice adopted, and vegetation features.

Great Plains Research↗

Point counts of birds: what are we estimating?

Point counts of birds are made for many reasons, including estimating local densities, determining population trends, assessing habitat preferences, and exploiting the activities of recreational birdwatchers. Problems arise unless there is a clear understanding of what point counts mean in terms of actual populations of birds. Criteria for conducting point counts depend strongly on the purposes to which they will be put. This paper provides a simple mathematical conceptualization of point counts and illustrates graphically some of the influences on them.

General Technical Report↗

Birds of Isle Royale in Lake Superior

This report constitutes an annotated list of 197 species of birds reported from Isle Royale National Park, a 210-square-mile archipelago in northwestern Lake Superior including some 200 islets and rock outcrops. The island is 45 miles long and 8 miles wide at its widest point. Bird distribution and habitats are described, along with geography and vegetation; 62 species are known to have bred at least once, 26 are thought to be breeders, and the rest are migrants.

Special Scientific Report - Wildlife↗

Grassland bird use of Conservation Reserve Program Fields in the Great Plains

The area enrolled in the Conservation Reserve Program in the Great Plains is enormous: nearly 18 million acres, or more than 7 million hectares, in Montana, North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, and Texas. This change in land use has had a huge influence on grassland bird populations. Many, but certainly not all, grassland species flourish in CRP habitats. Responses to the program vary not only by species, but by region, year, vegetation composition in a field, and whether or not a field was hayed or grazed. Further, the large scale of CRP has allowed researchers to begin to address other important conservation questions, such as the effect of the size of habitat patch and the influences of landscape features. Although the CRP provisions of farm bills have been beneficial to grassland birds, it is critical that gains in grassland habitat induced by the program not be offset by losses due to sodbusting.

Technical Report↗

A.B.A. Checklist: Birds of Continental United States and Canada

The purpose of this Checklist is to provide a complete up-to-date list of the bird species that have been recorded in the 49 continental United States and Canada. This list includes the native North American breeding species, the regular visitors, the accidentals from other countries that are believed to have strayed here without the direct aid of man, and those introduced species that have become well established and are now a true part of our avifauna. The A.B.A. Checklist will be revised at frequent intervals to keep up with changes in classification and additions to the avifauna. This edition includes a total of 794 species. For details of geographic range and for a complete list of re<;ognized subspecies the reader is referred to the latest (5th) edition of the A. O. U. Check-List of North American Birds, prepared by a committee of the American Ornithologists' Union, 1957, and to the 32nd Supplement published in April 1973 (Auk 90:411-419).

Book↗

The use of forward looking infrared to locate bird carcasses in agricultural areas

Helicopter-mounted Forward Looking Infrared has mainly been used for large animal censuses. I examined the use of this instrument in locating bird carcasses in agricultural fields to improve current carcass searching techniques. Mallard (Arias platyrhynchos) and northern bobwhite quail (Colinus virginianus) carcasses were measured with an infrared thermometer immediately following death and for 5 consecutive nights to determine the optimal time for detection. Preliminary flights were conducted to design a protocol that was used in test flights. Bird species (mallard versus quail) and cover type (bare ground versus short grass) were compared in the flights. Carcasses were recovered with the aid of Global Positioning Systems. Carcasses remained above ambient ground temperatures for all or part of night 1. Quail carcass temperatures decreased faster than mallard carcasses. In warmer weather, carcass temperatures increased 3-5 nights following death. In colder weather, carcasses were 1-2 C cooler than the ground after the first night. Mallard and quail carcasses were both detected on bare ground and short grass cover types with Forward Looking Infrared. The carcass recovery rates were 40% arid 30% on bare ground and short grass, respectively. There were no significant differences in detection for species or cover type. In warmer weather, carcasses could be detected for several hours following death and again 3-5 nights after death. Carcasses may be detected as objects cooler than the ground in colder weather. Forward Looking Infrared was successful in detecting mallard and quail carcasses. Further research should evaluate improved mapping techniques to enhance carcass recovery.

Book↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗