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At least 505 records · Page 28Linked to original sources
USGS2007

Potential environmental contaminant risks to avian species at important bird areas in the northeastern United States

Environmental contaminants, acting at molecular through population levels of biological organization, can have profound effects upon birds. A screening level risk assessment was conducted that examined potential contaminant threats at 52 Important Bird Areas (IBAs) in the northeastern Atlantic coast drainage. Using geographic information system methodology, data layers describing or integrating pollutant hazards (impaired waters, fish or wildlife consumption advisories, toxic release inventory data, estimated pesticide use and hazard) were overlaid on buffered IBA boundaries, and the relative contaminant threat for each site was ranked. The 10 sites identified as having the greatest contaminant threats included Jefferson National Forest, Stewart B. McKinney National Wildlife Refuge, Great Dismal Swamp National Wildlife Refuge, Blue Ridge Parkway, Shenandoah National Park, Adirondack Park, Edwin B. Forsythe National Wildlife Refuge, George Washington National Forest, Green Mountain National Forest, and Long Island Piping Plover Beaches. These sites accounted for over 50% of the entire study area, and in general had moderate to high percentages of impaired waters, fish consumption advisories related to mercury and PCBs, and were located in counties with substantial application rates of pesticides known to be toxic to birds. Avian species at these IBAs include Federally endangered Roseate terns (Sterna dougallii), threatened piping plovers (Charadrius melodus), neotropical migrants, Bicknell?s thrush (Catharus bicknelli), Swainson?s warbler (Limnothlypis swainsonii) and wintering brant geese (Branta bernicla). Extant data for free-ranging birds from the Contaminant Exposure and Effects--Terrestrial Vertebrates database were examined within the buffered boundaries of each IBA, and for a moderate number of sites there was qualitative concordance between the perceived risk and actual contaminant exposure data. However, several of the IBAs with substantial contaminant hazards (e.g., Blue Ridge Parkway, George Washington National Forest, Shenandoah National Park) had no recent avian ecotoxicological data. Contaminant biomonitoring is warranted at such sites, and data generated from such efforts should foster natural resource management activities.

Book chapter↗
USGS1979

Agnonistic behavior in short-billed dowitchers feeding on a patchy resource

In this paper we describe an instance of unusual, agonistic behavior in a flock of migrant Short-billed Dowitchers ( Limnodromus griseus ) . We compare this behavior to that of other flocks feeding at the same time at other locations in the same estuary and then present evidence suggesting that this behavior resulted from the patchy distribution of the probable foraging resource of this flock, eggs of the horseshoe crab ( Limulus polyphemus ). We propose that an extremely patchy resource has increased the agonistic behavior within the flock by increasing the variation in foraging success among individuals.

The Wilson Bulletin↗
USGS1977

Breeding densities and migration periods of common snipe in Colorado

Breeding densities and migration periods of Common Snipe in Colorado were investigated in 1974-75. Sites studied were near Fort Collins and in North Park, both in north central Colorado; in the Yampa Valley in northwestern Colorado; and in the San Luis Valley in south central Colorado....Estimated densities of breeding snipe based on censuses conducted during May 1974 and 1975 were, by region: 1.3-1.7 snipe/ha near Fort Collins; 0.6 snipe/ha in North Park; 0.5-0.7 snipe/ha in the Yampa Valley; and 0.5 snipe/ha in the San Luis Valley. Overall mean densities were 06 and 0.7 snipe/ha in 1974 and 1975 respectively. On individual study sites, densities of snipe ranged from 0.2 to 2.1 snipe/ha. Areas with shallow, stable, discontinuous water levels, sparse, short vegetation, and soft organic soils had the highest densities.....Twenty-eight nests were located having a mean clutch size of 3.9 eggs. Estimated onset of incubation ranged from 2 May through 4 July. Most nests were initiated in May.....Spring migration extended from late March through early May. Highest densities of snipe were recorded in all regions during l&23 April. Fall migration was underway by early September and was completed by mid-October with highest densities occurring about the third week in September. High numbers of snipe noted in early August may have been early migrants or locally produced juveniles concentrating on favorable feeding areas.

The Wilson Bulletin↗
USGS2008

Atlantic Flyway review: Region IV Piedmont-Coastal Plain, Fall 2007

Region IV welcomed another coastal station in 2007 with a report from Chris Snook at Charleston, South Carolina. The season was hot and dry throughout Region IV except in Florida where precipitation averaged above normal. Banders blamed their poor success on the lack of cold fronts in August, September, and the first half of October and on persistent strong east winds that blew the migrants farther inland. At Bill Baggs State Park in Miami no significant cold fronts were encountered until 25 Oct, and then on 29 Oct they banded over 100 Black-throated Blue Warblers that should have been on their West Indian wintering grounds by that date. Myrtle Warblers continued to be the most commonly banded species in Region IV, although numbers were down considerably from the previous autumn; their age ratios ranged from 25% hatching year (HY) at inland Tallahassee to 100% HY at coastal Chincoteague. Gray Catbird, which made the top ten list at all11 stations, was in second place, with percent of HYbirds ranging from 54% at Laurel to 95% at Chincoteague. Peak migration days ranged from 19 Sep in Laurel to 14 Nov at Kiptopeke, with five stations reporting their peak during 10-15 Oct. Thanks to the dedicated banders and assistants who contributed 61,825 net-hours in autumn 2007 to band 22,424 birds in Region IV. Thanks also to colleagues Deanna Dawson and John R. Sauer for their helpful comments.

North American Bird Bander↗
USGS1980

Situation report: Heavy DDT contamination at Wheeler National Wildlife Refuge

A DDT manufacturing plant that operated on the Redstone Arsenal near Huntsville, Alabama discharged DDT-Iaden effluent from 1947 to 1970 into a creek on Wheeler National Wildlife Refuge. Seven to 9 years after the plant closed, high DDT, DDE, and DDD levels were reported in soils, river sediments, and fish in the area. Eleven of 27 mallards (Anas platyrhynchos) collected on the Refuge during February 1979 had carcass DDE residues that exceeded levels associated with eggshell thinning. DDE residues in a smaller number of mallards exceeded levels associated with egg breakage, poor hatchability, and abnormal hehavior and poor survival of offspring. Several avian species have disappeared from the Refuge since 1950, probably due to both industrial discharges of DDT from the plant and insecticidal use of DDT in the area. The contamination still presents a threat to herons, waterfowl, and raptors including occasional wintering or migrant eagles (Haliaeetus leucocephalus), and probably many other avian species. A maternity colony of endangered gray bats (Myotis grisescens) is also threatened by this contamination.

Proceedings of the Annual Conference of the Southe↗
USGS1982

Migratory peregrine falcons, Falco peregrinus, accumulate pesticides in Latin America during winter

Blood samples from 433 Peregrine Falcons (Falco peregrinus) during fall and spring migrations, 1976-80, indicated that most of their pesticide burden, primarily DDE, was accumulated on wintering grounds in Latin America. DDE in spring migrants returning from Latin America for the first time declined significantly from 1979 to 1980. Only about 10% of breeding-age females contained organochlorine residues likely to adversely affect reproduction. The organochlorine pesticide threat in Latin America may be diminishing.

Canadian Field-Naturalist↗
USGS1985

Breeding chronology, molt, and measurements of accipiter hawks in northeastern Oregon

Most northern goshawks completed laying eggs in April, while most Cooper's hawks completed their clutches in May with essentially no overlap. The sharp-shinned hawks laid in late May and June. Juvenile females represented 4% of the northern goshawk breeding population; 22% of the Cooper's hawk breeding population (highest reported for the species) and 60% of the sharp-shinned hawk breeding population, northern goshawks and Cooper's hawks in juvenal plumage generally nested later in the season, but not sharp-shinned hawks. Females of each species began molting first. Primaries were molted from the innermost outward in all species, but rectrix molt sequence was variable. Usually R1 was molted first. Primary molt of the 2 wings was usually synchronous; however, the rectrix molt was not as orderly. Arrested molt was observed in some individuals of all species; it probably has an energy-saving function. Wing chords of adult northern goshawks from Oregon were not different from Wisconsin fall migrants or birds from Alaska; however, rectrices were significantly shorter in Oregon than Wisconsin. Cooper's hawks nesting in Oregon were much smaller than those trapped in Wisconsin. Wing chords and rectrices were significantly shorter for both sexes, and, although weights were not directly comparable, Oregon Cooper's hawks also weighed much less. The limited number of sharp-shinned hawks measured precluded statistical analyses.

Journal of Field Ornithology↗
USGS1995

North American migratory bird management issues

As human population and industry have grown in North America, land-use practices have greatly altered the landscape. As a result of this changed landscape, several migratory bird populations have declined in recent years. For waterbirds, there have been several milestones: the 1986 North American Waterfowl Management Plan (NAWMP) and the 1989 North American Wetlands Conservation Act. As a result, the United States and Canada have established 12 habitat and 2 species joint ventures. The primary emphasis of waterfowl management in Canada-U.S. has been land purchase and lease, wetland restoration, and coordination of harvest rates. Because of its different biological and cultural context, Mexico has established other conservation priorities. Mexico has had a long-standing concern to conserve its biodiversity and, in addition, conservation of Mexican resources goes hand in hand with human community development. Unlike Canada-U.S., wetland conservation projects in'Mexico include information gathering, environmental education, and management planning for its 32 priority wetlands. For migratory landbirds' scientists attribute declines in several migrant populations to forest fragmentation on the breeding grounds, deforestation on the wintering grounds, pesticide poisoning, or the cumulative effects of habitat changes. In 1990, the Neotropical Migratory Bird Conservation Program, commonly known as Partners in Flight-Aves de las Americas-was initiated. The next step that is being proposed is the formation of a habitat conservation plan for landbirds modeled after the NAWMP. Management of migratory birds requires a strong international approach in order to coordinate actions for the benefit of migratory birds, their habitats, and the uses they provide.

Wildlife Society Annual Conference↗
USGS1989

Kirtland's warblers on the nesting grounds during the post- breeding period

Information indicates that a substantial number of breeding birds remain in Michigan through September, and a few individuals probably remain into early October. Migration apparently consists of two waves of migrants: an early departure (mid-August to early September); and late departure (late September). Based on our findings, we recommend that major Kirtland's warbler areas be kept closed into mid-September.

The Wilson Bulletin↗
USGS1994

Falcon versus grouse: flight adaptations of a predator and its prey

Several falcons were trained to fly along a 500 m course to a lure. The air speeds of the more consistent performers averaged about 1.5 times their calculated minimum power speeds, and occasionally reached 2.1 times the minimum power speed. Wing beat frequencies of all the falcons were above those estimated from earlier field observations, and the same was true of wild Sage Grouse Centrocercus urophasianus, a regular falconer's quarry in the study area. Measurements of grouse killed by falcons showed that their wings were short, with broad slotted tips, whereas the falcons' wings were longer in relation to their body mass, and tapered. The short wings of grouse result in fast flight, high power requirements, and reduced capacity for aerobic flight. Calculations indicated that the grouse should fly faster than the falcons, and had the large amount of flight muscle needed to do so, but that the falcons would be capable of prolonged aerobic flight, whereas the grouse probably would not. We surmise that Sage Grouse cannot fly continuously without incurring an oxygen debt, and are therefore not long-distance migrants, although this limitation is partly due to their large size, and would not apply to smaller galliform birds such as ptarmigan Lagopus spp. The wing action seen in video recordings of the falcons was not consistent with the maintenance of constant circulation. We call it 'chase mode' because it appears to be associated with a high level of muscular exertion, without special regard to fuel economy. It shows features in common with the 'bounding' flight of passerines.

Journal of Avian Biology↗
USGS1994

Partial migration and wintering localities of American kestrels nesting in the Pacific northwest

Based on banding recoveries, an estimated 89.5% of American kestrels (Falco sparverius) nesting in eastern Oregon, eastern Washington, and Idaho (excluding the Snake River Plain) are migratory and primarily migrate to western Mexico for the winter. Band recoveries from Mexico may be biased; however, we do not know whether the bias is toward more or fewer recoveries. The banding data imply that the remaining kestrels from the region (10.5%) are permanent residents, and we found 2.8% of a northeastern Oregon population on nesting territories in January 1981 (permanent residents). A higher percentage of the nesting population appears to be permanent residents in the valleys along the Snake River Plain than in the remainder of Idaho, eastern Oregon, and eastern Washington (p = 0.02). Limited evidence shows that permanent resident kestrels in eastern Oregon nest earlier than migrants. Information available for the population west of the Cascade Mountains in Oregon and Washington was limited.

Northwestern Naturalist↗
USGS1997

Migration chronology and distribution of redheads on the lower Laguna Madre, Texas

An estimated 80% of redheads (Aythya americana) winter on the Laguna Madre of southern Texas and Mexico. Because there have been profound changes in the Laguna Madre over the past three decades and the area is facing increasing industrial and recreational development, we studied the winter distribution and habitat requirements of redheads during two winters (1987-1988 and 1988-1989) on the Lower Laguna Madre, Texas to provide information that could be used to understand, identify, and protect wintering redhead habitat. Redheads began arriving on the Lower Laguna Madre during early October in 1987 and 1988, and continued to arrive through November. Redhead migration was closely associated with passing weather fronts. Redheads arrived on the day a front arrived and during the following two days; no migrants were observed arriving the day before a weather front arrived. Flock size of arriving redheads was 26.4 ± 0.6 birds and did not differ among days or by time of day (morning midday, or afternoon). Number of flocks arriving per 0.5 h interval (arrival rate) was greater during afternoon (21.7 ± 0.6) than during morning (4.3 ± 1.2) or midday (1.5 ± 0.4) on the day of frontal passage and during the first day after frontal passage. Upon arrival, redhead flocks congregated in the central portion of the Lower Laguna Madre. They continued to use the central portion throughout the winter, but gradually spread to the northern and southern ends of the lagoon. Seventy-one percent of the area used by flocks was vegetated with shoalgrass (Halodule wrightii) although shoalgrass covered only 32% of the lagoon. Flock movements seemed to be related to tide level; redheads moved to remain in water 12-30 cm deep. These data can be used by the environmental community to identify and protect this unique and indispensable habitat for wintering redheads.

Texas↗
USGS1998

Atlantic Flyway review: Piedmont-Coastal Plain Region IV - Fall 1997: Robbins Nest, Laurel, MD (390-0765)

The 25th year of fall banding at this back yard station atop the Patuxent River gorge between Laurel and the 1-95 bridge netted more birds of summer and winter resident species than migrants. Myrtle Warbler was the only one of the six commonest species captured that is primarily a transient here. My 5214 net-hours, my fourth highest, were 48% above the 24-year mean of 3512, but the only species to exceed their previous high were Carolina Chickadee and Magnolia Warbler. Part of the reason for my low catch per 100 net-hours in recent years is the dieoff of dogwood from anthracnose and destruction of the shrub layer in my mature woods by an overpopulation of deer. For the first time, deer destroyed three of my nets. We also had the driest summer in decades, which killed some of the shallow-rooted vegetation this year. The greatest declines from last year were in catbird (51 to 32), Hermit Thrush ( 27 to 12 ), and Blackand-white Warbler (11 to 3), and the greatest increases were in Myrtle Warbler (2 to 34), Carolina Chickadee (6 to 36), and Tufted Titmouse (10 to 31). The biggest changes from the mean of the first five years (1973-77) to the most recent five years (1993-97), not corrected for the 147% increase in net-hours, are increases in Rubythroated Hummingbird (1.2 to 7.6 ), Black-throated Blue Warbler (1.8 to 11.6), Common Yellowthroat (5.0 to 17.6), and House Finch (0.2 to 6.0), and decreases in Swainson's Thrush (26.6 to 17.2), Gray-cheeked/Bicknell's Thrush (9.4 to 3.8), Scarlet Tanager (6.6 to 2.2), and American Goldfinch (3.0 to 0.4). The oldest of my 39 returns were a six-year-old Gray Catbird and a five-year-old Carolina Chickadee. Two birds banded here during the fall migration of 1995 were found to the northeast of here in the summer of 1997: a Ruby-throated Hummingbird (8000-85102) in Philadelphia, PA, and a Hermit Thrush (1521-58503) at Wentworth, NH. A Savannah Sparrow was the 121st species banded on our suburban wooded hectare.

Maryland↗
USGS1999

Density and habitat of breeding Swallow-tailed Kites in the lower Suwannee ecosystem, Florida

Historically the Swallow-tailed Kite (Elanoides forficatus) bred in the United States in at least 16 eastern states. Currently it is restricted to seven southeastern states, with most of its breeding range in Florida. Breeding Bird Surveys indicate a declining trend for this Neotropical migrant in most of Florida. Using a rapid survey technique at the Lower Suwannee NWR on 25-27 Mar. 1997, we scanned for kites from 16 sampling stations above the forest canopy, using 10X binoculars for 45 min per station. An effective detection distance of 2.4 km provided almost complete coverage of kite habitat (excluding salt marsh) on the refuge (14,620 ha) and in a 1.6-km buffer (13,526 ha). A mobile observation platform, extended to heights of 30-34 m provided an unobstructed view above the forest canopy where foraging bouts, feeding, courtship displays, and other activities by this species occur. This technique was found to be efficient in obtaining an estimate of potential breeding pairs. An estimated 19 breeding pairs were observed, with possibly five additional pairs, a density of at least one pair per 1173-1407 ha. There was no opportunity to search for nests so we were unable to correlate number of active nests with the number of kites observed, and linear nature of study area might concentrate birds, including nonbreeders, so our density of kites may or may not be typical for other areas. The refuge has a mosaic of 11 different habitats (7 forest types, freshwater and salt marshes, open water and urban/suburban) providing much linear edge to the matrix of different plant communities that range in height from less than 1 m to greater than 30 m. Such structure provides quality habitat for Swallow-tailed Kites.

Journal of Field Ornithology↗
USGS2001

Ground-nesting waterbirds and mammalian carnivores in the Virginia barrier island region: Running out of options

We examined changing patterns of distribution of two large mammalian predators, the raccoon (Procyon lotor) and red fox (Vulpes vulpes), and beach-nesting terns and Black Skimmers (Rynchops niger) along ca. 80 km of the Virginia barrier island landscape between the periods 1975-1977 and 1998. Based on evidence from trapping, scent stations, den observations and sightings of the two predators, there has been a marked increase in their island ranges. In 1975-77, only 6 of the 11 surveyed barrier islands definitely harbored at least one of the two mammals, but by 1998, 11 of 14 islands showed evidence of one or both during the spring and summer. Concurrently, annual beach-nesting bird surveys have been conducted since the mid 1970s during June. From 1977 to 1998, the number of colonies of terns [Common (Sterna hirundo), Gull-billed (S. nilotica), Least (S. antillarum), Royal (S. maxima), and Sandwich (S. sandvicensis)] and Black Skimmers declined from 23 colonies on 11 barrier islands to 13 colonies on 10 islands. In addition, the populations decreased dramatically for all species except the marginal Sandwich Tern and Least Tern. This pattern suggests that mammalian predation may be a major factor in colony site selection or success, although we have no data on success at most locations. The only consistently large colony over the years has been the Royal Tern colony on Fisherman Island, one of the few with no resident large mammals. Because these declining waterbirds appear to be running out of options for safe colony sites in coastal Virginia, we discuss the prospects of conducting limited predator removals on certain islands. In addition, considerations of strict management and enforcement of protection at critical manmade colony sites that now attract large numbers of certain species, are timely. Lastly, where dredged material disposal projects are planned, providing nesting sites for these colonial species and roosting sites for migrant birds may be appropriate.

Journal of Coastal Research↗
USGS2000

The 1995-1999 Summary of the North American Breeding Bird Survey

Data from the North American Breeding Bird Survey were used to estimate continental and regional changes in bird populations for the 5-yr period 1995-1999 and the 2-yr period 1998-1999. These short-term changes were placed in the context of population trends estimated over the 1966-1999 interval. During 1995-1999, 44% of all species exhibited positive trends over the entire survey area, while 44% of all species exhibited positive trends during 1998-1999; neither of these percentages differed significantly from 50%. The continental and regional percentages of species with positive trends were also analyzed for 12 species groups having shared life-history traits. Survey-wide for the entire survey period, grassland birds exhibited the lowest percentage of increasing species (19%). However, during 1995-1999 the declines were less extreme in the Central and Western BBS regions, with 49% and 36% of species increasing in these regions. Neotropical migrants continued to fare better than grassland birds in all regions, although in the Eastern BBS region only 30% of neotropical species had increasing trends during 1995-1999.

Bird Populations↗
USGS2001

Inability to predict geographic origin of Yellow-headed Blackbirds, Xanthocephalus xanthocephalus, during migration

Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) collected at different breeding locations in Alberta, Saskatchewan, Manitoba, and North Dakota exhibit clearly discernable morphometric differences with larger bodied birds found at more northern and western locations. We reduced eight skeletal measurements and body length from adult female and male Yellow-headed Blackbirds to their first two principal components. Principal component scores progressively increased at more northwestern locations. Principal component scores were also derived from measurements of birds collected in central North Dakota throughout summer and fall. We hypothesized an increase in principal component scores of Yellow-headed Blackbirds from summer through fall within central North Dakota as larger bodied migrants arrived and displaced local breeding birds. However, we were unable to detect an increase in principal component scores from mid-June though mid-September over two years of study. Discriminant models that were developed to distinguish birds breeding in Canada from those breeding in the USA were poor predictors of the migratory status of Yellow-headed Blackbirds. Thus, we were unable to exploit the morphometric differences inherent among Yellow-headed Blackbirds breeding at different geographic locations to quantify the timing or the magnitude of their migration through central North Dakota.

Canadian Field-Naturalist↗
USGS2004

Atlantic Flyway review: Region IV - Fall 2003: Robbins Nest, Laurel, MD (390-0765)

The most notable finding at this station in 2003 was the sharp decline in recaptures of previously banded birds and most especially a Crash in the chickadee and titmouse populations. In the autumn of 2001, I recaptured 36 birds banded in previous autumns, but I caught only 24 returns in 2002 and 17 in 2003, a 33% drop each year. In 2002, Tufted Titmouse was my fourth most common species (19 caught) and Carolina Chickadee (15)was in seventh place. This year, I had only four titmice and six chickadees, declines of 79% and 60%. Until now, only the migratory species have been of concern. We suspect West Nile virus is responsible. However, the oldest bird we recaptured this year was Blue Jay 723-42798, banded as HY in 1993, a species known to be especially vulnerable to West Nile. Half of this year's returns were cardinals, the oldest of which was only four years of age. My birds/100nh continues to drop each year without any noticeable change in surrounding habitat. The only banded migrant known to have remained here for more than a week was a Swainson's Thrush that weighed 31.9 g on 4 Oct and 41.6 g nine days later, an increase of 30%.

Maryland↗