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At least 1,117 records · Page 62Linked to original sources
USGS1989

Population declines in North American birds that migrate to the neotropics

Using data from the North American Breeding Bird Survey, we determined that most neotropical migrant bird species that breed in forests of the eastern United States and Canada have recently (1978-1987) declined in abundance after a period of stable or increasing populations. Most permanent residents and temperate-zone migrants did not show a general pattern of decrease during this period. Field data from Mexico were used to classify a subset of the neotropical migrants as using forest or scrub habitats during winter. Population declines during 1978-1987 were significantly greater among the forest-wintering species, while populations of scrub-wintering species increased. The same subset of neotropical migrants also showed overall declines in forest-breeding species, but no significant differences existed between species breeding in forest and scrub habitats. Neotropical migrant species that primarily use forested habitats in either wintering or breeding areas are declining, but a statistically significant association between habitat and population declines was detected only in the tropics.

Proceedings of the National Academy of Sciences↗
USGS1974

Progress report on the North American Breeding Bird Survey

The Breeding Bird Survey has been monitoring bird population changes in the U.S.A. and Canada since 1966. Each cooperator makes 50 3-minute stops at 0.8-km intervals along randomly selected roadside routes in 4 to 4 1/2 hours on one morning in June of each year. Data from the 1500 to 1600 routes are entered on magnetic tape, edited for accuracy, and then used for statistical analysis of population change at four geographic levels: physiographic region; state or province; region (eastern, central and western); and the continent. Examples of use of the data are: (1) detection of year-to-year changes in continental or rcgional populations; (2) use of population indices to show long-term population changes; (3) range expansion and contraction at the state level, including some of the reasons for those changes and documenting the associated population shifts within the original range; (4) mapping distribution and relative abundance on either a state, regional or continental scale; (5) mapping changes in abundance; and(6) comparing breeding with winter distribution. Future potential uses will include estimates of total continental populations and indices of environmental quality.

Acta Ornithologica↗
USGS1990

Capture-recapture estimation of prebreeding survival rate for birds exhibiting delayed maturation

Many species of seabirds exhibit delayed maturity and do not return to the natal colony to breed for several years after fledging. Capture-recapture studies are frequently conducted at such breeding colonies and often include marking of young birds. However, because of the absence of these birds from the natal colony during the first few years after banding, the data do not fit neatly into existing capture-recapture models. Here we present a method for estimating prebreeding survival rate from capture-recapture studies on species exhibiting such patterns of delayed maturation. We illustrate the method using data from a capture-recapture study of Roseate Terns (Sterna dougallii ) on Falkner Island, Connecticut. The method appears to work well and emphasizes the potential to tailor capture-recapture models to specific field situations.

Journal of Field Ornithology↗
USGS1992

Fifty-fifth Christmas Bird Count. 159. Ocean City, Md

The distribution of dynamic pressure behind a Harris' hawk's wing was sampled using a wake rake consisting of 15 pitot tubes and one static tube. The hawk was holding on to a perch, but at an air speed and gliding angle at which it was capable of gliding. The perch was instrumented, so that the lift developed by the wing was known and the lift coefficient could be calculated. The mean of 92 estimates of profile drag coefficient was 0.0207, with standard deviation 0.0079. Lift coefficients ranged from 0.51 to 1.08. Reynolds numbers were nearly all in the range 143000-194000. The estimates of profile drag coefficient were reconcilable with previous estimates of the wing profile drag of the same bird, obtained by the subtractive method, and also with values predicted by the `Airfoil-ii? program for designing aerofoils, based on a digitized wing profile from the ulnar region of the wing. The thickness of the wake suggested that the boundary layer was mostly or fully turbulent in most observations and separated in some, possibly as an active means of creating drag for control purposes. It appears that the bird could momentarily either increase or decrease the profile drag of specific parts of the wing, by active changes of shape, and it appeared to use the carpo-metacarpal region especially for such control movements. Further investigation in a low turbulence wind tunnel would help to resolve doubts about the possible influence of airstream turbulence on the behaviour of the boundary layer.

Journal of Experimental Biology↗
USGS1987

Longevity records of North American birds: Coerebinae through Estrildidae

This is the fourth paper of a 4-part series detailing the longevity records of marked North American birds. The previous three papers can be found in the Journal of Field Ornithology, Volumes 53 and 54. Prio to this series only one definitive paper ( Kennard 1975) had been written on North American taxa. Records for 84 taxa are included in this paper. Thirty are birds older than those listed by Kennard. Thirty-nine are new records and 9 are those listed in Kennard.

Journal of Field Ornithology↗
USGS1996

Neotropical migratory breeding bird communities in riparian forests of different widths along the Altamaha River, Georgia

-We surveyed riparian forest corridors of different widths along the lower Altamaha River in Georgia in 1993 and 1994 to investigate the relationship between forest corridor width and Neotropical breeding bird community diversity and abundance. Species richness and abundance of three of six focal species increased with increasing forest corridor width. We suggest if Neotropical breeding bird communities are a target group, that land managers should consider leaving a 100 m buffer strip along riparian zones.

The Wilson Bulletin↗
USGS1997

Bottomland hardwood reforestation for neotropical migratory birds: Are we missing the forest for the trees?

Reforestation of bottomland hardwoods on lands managed for wildlife or timber production has historically emphasized planting heavy-seeded oaks (Quercus spp.). Although techniques have been developed for successful oak establishment, these plantings often require 5 or more years before establishing a 3-dimensional forest structure. We suggest that lands planted to fast-growing early-successional species, in combination with oaks, provide: (1) more expedient benefits to Neotropical migratory birds; (2) greater forest diversity; (3) more rapid economic return to landowners; and (4) enhanced public relations. Under good growing conditions, and with effective weed control, some fast-growing species can develop a substantial 3-dimensional forest structure in as few as 2 or 3 years. Forest-breeding Neotropical migratory birds use stands planted with early successional species several years before sites planted solely with oaks. Where desirable, succession to forests with a high proportion of oak species can be achieved on sites initially planted with fast-growing species through silvicultural management.

Wildlife Society Bulletin↗
USGS1985

[Book review] The birds of San Diego County

San Diego County, California is larger in area than 2 of the 50 states (combined), its geographic (and thus biological) diversity ranges from the seacoast across mountains of nearly 2,000 m elevation to extreme desert, it is the southwesternmost county of the contiguous U.S., and it is inhabited by dedicated birders whose observations have boosted the county list to more than 450 species. "The Birds of San Diego County" provides detailed information on the geographic, ecological, and temporal distribution and abundance of each of the 449 species of native birds reported in the county-for some, by subspecies. Maps of breeding distribution are presented for 129 of the 181 breeding species (of which 26 are considered to be extirpated or only occasional breeders). Ecological zones and terms of abundance are defined precisely, and the definitions are adhered to. Welcomely absent are long para- graphs of descriptive and generalized information.

The Auk↗
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,↗
USGS2004

Reproduction in nondomestic birds: Physiology, semen collection, artificial insemination and cryopreservation

Pioneering work by Quinn and Burrows in the late 1930s led to successful artificial insemination (AI) programs in the domestic poultry industry. A variety of species specific modifications to the Quinn and Burrows massage technique made AI possible in nondomestic birds. Massage semen collection and insemination techniques span the entire range of species from sparrows to ostriches. Also, cooperative semen collection and electroejaculation have found limited use in some nondomestic species. Artificial insemination produces good fertility, often exceeding fertility levels in naturally copulating populations. However, aviculturists should explore other ways to improve fertility before resorting to AI. Artificial insemination is labor intensive and may pose risks to nondomestic birds as well as handlers associated with capture and insemination. Semen collection and AI makes semen cryopreservation and germ plasma preservation possible. Yet, semen cryopreservation techniques need improvement before fertility with frozen-thawed semen will equal fertility from AI with fresh semen.

Avian and Poultry Biology Reviews↗
USGS1955

Fifty-fifth Christmas Bird Count. 159. Ocean City, Md

The distribution of dynamic pressure behind a Harris' hawk's wing was sampled using a wake rake consisting of 15 pitot tubes and one static tube. The hawk was holding on to a perch, but at an air speed and gliding angle at which it was capable of gliding. The perch was instrumented, so that the lift developed by the wing was known and the lift coefficient could be calculated. The mean of 92 estimates of profile drag coefficient was 0.0207, with standard deviation 0.0079. Lift coefficients ranged from 0.51 to 1.08. Reynolds numbers were nearly all in the range 143000-194000. The estimates of profile drag coefficient were reconcilable with previous estimates of the wing profile drag of the same bird, obtained by the subtractive method, and also with values predicted by the ?Airfoil-ii? program for designing aerofoils, based on a digitized wing profile from the ulnar region of the wing. The thickness of the wake suggested that the boundary layer was mostly or fully turbulent in most observations and separated in some, possibly as an active means of creating drag for control purposes. It appears that the bird could momentarily either increase or decrease the profile drag of specific parts of the wing, by active changes of shape, and it appeared to use the carpo-metacarpal region especially for such control movements. Further investigation in a low turbulence wind tunnel would help to resolve doubts about the possible influence of airstream turbulence on the behaviour of the boundary layer.

Audubon Field Notes↗
USGS1973

Sea birds wintering off Maryland shores, 1972-73

During the winter of 1972-73, studies were conducted to determine the status and distribution of pelagic species of birds occurring at sea as far as 38 miles east of Ocean City, Md. The wintering off-shore avifauna was found to be impressively rich in variety of species and numbers of individuals. Sightings included Fulmar and Skua, both first sight records for Maryland. Large alcids, especially Razorbills, were observed in unprecedented numbers and on five of the seven trips undertaken. Thick-billed Murre was sighted once and Dovekie, once. A Pomarine Jaeger was a mid-winter first for Maryland. Black-legged Kittiwakes were sighted on all seven trips, with age ratios consistently averaging about three adults to one immature. Likewise, Gannets were observed on all seven trips, 7.5 adults to one immature. Iceland Gulls were seen twice and Black-headed Gulls on three trips. Evidence of a definite migration was noted on Nov. 19, as Gannets were observed flying south in a narrow band, four miles wide, five to nine miles east of Ocean City, and Black-legged Kittiwakes, likewise, were heading south in a steady stream no closer than 14 miles east of Ocean City. Data accumulated from December through March suggest most pelagics occurring in Maryland waters during this period were truly wintering and not transients. This report is concerned primarily with the true pelagics normally found well away from the sight of land and does not dwell on those 'sea birds' commonly seen in immediate coastal waters.

Maryland Birdlife↗
USGS2011

Book review: Birds of Wyoming

"Wyoming may very well be one of the least birded states in the U.S." So begins this book, underscoring the challenges in summarizing existing knowledge for a state that falls next to last in human population density. Despite the relative dearth of "binoculars on the ground," especially in more remote areas of the state, the book offers a thorough compilation of relevant details. Much of this information is not readily accessible from other sources, and this book dispenses essential information in a very usable format. Review info: Birds of Wyoming . By Douglas W. Faulkner, 2010. ISBN: 978-1936221028, vii, 432 pp.

Prairie Naturalist↗
USGS2003

Human-induced contaminant impacts on migratory birds: Lessons from the North American eared grebe ( Podiceps nigricollis )

The effects of aquatic contaminants generated by soda ash mining processes on the North American eared grebe ( Podiceps nigricollis ) population illustrates important issues associated with human-induced habitat degradation on the health of migratory species. Eared grebes have been extensively studied in their staging and breeding habitats, but little is known about their 2- to 3-day migratory periods. During migration, few bodies of water are available to the birds for refuge between freshwater breeding areas in Canada and hypersaline lakes (e.g., Great Salt Lake in Utah or Mono Lake in California) to which they migrate. One geographic refuge area includes a series of "tailings" ponds associated with soda ash mining operations in southwestern Wyoming. The ponds range from 100-1200 acres, with water containing high concentrations of sodium decahydrate (Na 2 CO 3 &bull;10H 2 O). At cool temperatures (generally < 40&deg;F) sodium decahydrate precipitates out of the water and crystallizes on solid objects in the ponds or on the water surface. Bird mortality on these ponds has been recognized since the early 1970's, and the mining companies have developed hazing strategies and rehabilitation programs in order to minimize mortality. In order to determine causes of grebe mortality and devise strategies to reduce mortality, a field epidemiologic investigation was developed with the following objectives: 1) to determine whether eared grebes have quantifiable physiologic abnormalities associated with exposure to soda ash mine pond water; 2) to evaluate physical effects of sodium decahydrate crystallization on grebe survival; 3) to establish cause of death based on necropsy of deceased grebes; 4) to determine long-term survivability of eared grebes after exposure to the pond water; and 5) to evaluate water quality and determine whether aquatic invertebrates are present in the ponds as a possible food source.

California, Utah↗
USGS1997

A new approach for analyzing bird densities from variable circular-plot counts

An approach for calculating bird densities from variable circular-plot counts is described. The approach differs from previous methods in that data from several surveys are pooled and detection distances are adjusted as if all distances were recorded by a single observer under a given set of field conditions. Adjustments for covariates that affect detection distances such as observer, weather, time of day, and vegetation type are made using coefficients calculated by multiple linear regression. The effective area surveyed under standard conditions is calculated from the pooled data set and then used to determine the effective area surveyed at each sampling station under the actual conditions when the station was sampled. The method was validated in two field studies where the density of birds could be determined by independent methods. Computer software for entering and analyzing data by this method is described.

Pacific Science↗
USGS1999

The response of a Kansas winter bird community to weather, photoperiod, and year

We conducted a bird census along the same route nearly each week for 14 winters (194 censuses), and compared the mean number of species per station and the total number of species recorded on the census with the length of photoperiod and weather variables. We found significant differences among winters for both indicators of species richness. This result is consistent with previous studies in which abundance of food was measured in the same general area. Both indicators of species richness were negatively associated with the number of days after 1 November. This result is consistent with the hypothesis that wintering species dependent on nonrenewed food resources lose individuals to mortality or emigration. Further, there was a positive relationship between photoperiod and both indicators of species richness. This result is consistent with the hypothesis that the detection of individuals in the early morning hours increases with the amount of daylight they have available for foraging and social behaviors. Wind speed and temperature had negative and positive relationships, respectively, to species richness. The number of species per station was greatest on days when the ground was covered with dew and least on days when snow depth was more than 15 cm. When the 'winters' were divided into four 30-day 'quarters', most of the 61 species were recorded with equal frequency in each quarter. Eight species were detected less frequently at the end of winter than in the beginning. Four species exhibited the reverse pattern. Two species were recorded more frequently at the beginning and at the end of the winter than during the middle. Temperature, wind, photoperiod, successive winter day, year, and species-specific evolutionary history all affect winter bird species richness.

The Wilson Bulletin↗
USGS2002

Success of artificial bird nests in burned Gulf Coast Chenier Plain marshes

Wildlife managers in the Gulf Coast Chenier Plain of Louisiana and Texas frequently burn marshes during winter to improve habitat for wintering waterfowl and furbearers. Such fires dramatically alter vegetation structure and cover, although such changes are generally temporary. However, if vegetation cover does not recover sufficiently by the start of the subsequent breeding season, nests of marsh birds could be exposed to increased predation rates. We examined effects of burning on 2 measures of vegetation structure and on 2 types of artificial bird nests during breeding seasons (May and June) before and after experimental winter burns (December and January). We found that vegetation structure did not differ between burned and non-burned marshes at 5 months post-burn. Similarly, depredation rates of artificial sparrow and duck nests did not differ between burned and non-burned marshes during the post-burn breeding season. We recommend that managers complete burning programs by the end of January so that sufficient nesting cover develops before the start of the breeding season.

Southwestern Naturalist↗