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At least 487 records · Page 27Linked to original sources
USGS1992

Density of loons in central Alaska

Loons breed across North America from the high arctic south to about 43 north latitude. (AOU 1983). Populations, particularly of Common Loons ( Gavia immer ) have recently declined in the continental U.S. and southern Canada (Sutcliff 1979, Titus and VanDruff 1981, McIntyre 1988). As a result, state and private natural resource organizations began more intensive monitoring of loon populations (in McIntyre 1986, Strong 1988). These surveys, however, are restricted to areas accessible by road, although recently aircraft were used for more remote areas (Lee and Arbuckle 1988, Strong 1990).

Alaska↗
USGS1988

Length of stay and fat content of migrant semipalmated sandpipers in eastern Maine

Semipalmated Sandpipers (Calidris pusilla) stop at coastal staging areas in the Canadian maritime provinces and northeastern United States to replenish fat reserves before initiating a nonstop transoceanic flight of at least 3,200 km to wintering areas in South America. The relationship between estimated fat content at capture and length of stay (days between marking and last observation) of Semipalmated Sandpipers at one of these staging areas in eastern Maine was studied during 1980-1982. Total body mass and wing chord length were used to estimate fat content. When data were analyzed by week of initial capture, mean length of stay of both adults and juveniles decreased with increasing fat content. This supports the assumption that resumption of migration is affected by fat content at staging areas for long-distance nonstop flights. However, fat content at capture was a poor predictor of length of stay, which suggests that other factors are more important in determining length of stay.

Condor↗
USGS1991

Mortality of seabirds in the Japanese land-based gillnet fishery for salmon

Mortality rates of seabirds in the Japanese land-based drift gillnet fishery for salmon were assessed from 413 gillnet sets made by Japanese research vessels in offshore areas used by the commercial fleet. Sixteen species of seabirds were recorded in nets. Shearwaters, primarily Short-tailed Shearwaters ( Puffinus tenuirostris ), and to a lesser extent Sooty Shearwaters ( P. griseus ), predominated in the catches, followed by lesser numbers of Tufted Puffins ( Fratercula cirrhata ) and Thick-billed Murres ( Uria lomvia ). Catch-rates of seabirds varied by oceanographic zone, with most being caught in oceanic waters north of the Subarctic Front. Approximately 151,000 seabirds were killed in the offshore component of the land-based fishery in 1977. Mortality was reduced to about 57,000 seabirds in 1987 because of a reduction in fishing effort. No estimates are available of seabird mortality in the nearshore component of the fishery. Mortality of seabirds in the land-based fishery is discussed with respect to other major drift gillnet fisheries in the North Pacific.

The Condor↗
USGS1991

Evidence for color phase effects on the breeding and life history of Northern Fulmars

About 15% of Northern Fulmars ( Fulmarus glacialis ) breeding on the Semidi Islands in 1979 had light-phase plumage; the remainder were dark. Fulmars of different plumage types mated indiscriminantly, but the lighter member of a mixed pair was more likely to be male than female. Pairs that included at least one light-phase member had lower breeding success than dark/dark pairs in one of six years. Constancy of breeding site use differed between light/dark and dark/dark pairs, suggesting dark birds skipped more breeding attempts or had lower over-winter survival than light birds. The apparent effect of breeding experience (assessed by site fidelity) on success also differed between pair types. The polymorphism on the Semidi Islands may result from light-phase fulmars immigrating from the Bering Sea, but there is also evidence to suggest it is maintained by balancing selection in a closed population.

Alaska↗
USGS1995

Variation in brood behavior of Black Brant

We studied behavior of broods of Black Brant ( Branta bernicla nigricans ) during five summers between 1987 and 1993, a period in which the local breeding population increased >3-fold. Goslings spent more time foraging than adults of either sex, while adult males spent more time alert and less time foraging than adult females. Percentage of time spent alert was positively correlated with brood size for adult males but not adult females. Foraging time for all age and sex classes increased with date following hatch within years. Foraging time increased and time spent alert decreased between 1987 and 1993 for both adult males and adult females. The trend in foraging behavior for adults is consistent with an hypothesis of declining food availability at higher brood densities and declining alert behavior by adults has implications for prefledging survival of young.

Alaska↗
USGS1995

Metabolizability and partitioning of energy and protein in green plants by yearling lesser snow geese

We measured apparent metabolizability of organic matter, gross energy, nitrogen and cell wall constituents of pelleted alfalfa by Lesser Snow Geese ( Chen caerulescens caerulescens . We also used simultaneous measurements of energy expenditure and apparent metabolizable energy intake to estimate heat increment of feeding and net energy for production and maintenance. Apparent metabolizability of energy was 46% as a result of substantial retention of dietary cellulose (45%). Mean slope of the relationship between energy expenditure and apparent metabolizable energy intake, which estimates heat increment at feeding, was 0.33. One minus the slope, 0.67, was our estimate of the proportion of apparent metabolizable energy available for maintenance and production. Resting metabolic rate at zero apparent metabolizable energy intake ranged from 361 kJ· kg -1 · day -1 to 432 kJ· kg -1 · da y-1 , while apparent metabolizable energy intake required for energy balance ranged from 455 kJ· kg -1 · day -1 to 871 kJ· kg -1 · day -1 . Lesser Snow Geese (>2 kg mass) were more efficient at retaining dietary energy but possibly lost more of this energy as heat than smaller Black Brant ( Branta bernicla nigricans )(∼1 kg mass), suggesting a possible relationship between body size and processing of energy in herbivorous birds.

Alaska, Northwest Territories↗
USGS1995

Morphological differences in Pacific Coast populations of greater white-fronted geese

We examined morphological relationships of three Pacific coast populations of Greater White-fronted Geese (Anser albifrons). Adult geese were captured and measured at three breeding areas in Alaska and two wintering areas in California, 1980-1991. A two-step discriminant function analysis examined morphological differences among the three populations. Stepwise discriminant function procedures created the simplest measurement models. Each sex was analyzed separately since multivariate analysis of variance indicated that males were significantly larger than females for all three populations. Tule Greater White-fronted Geese (A. a. gambelli) were significantly larger than Pacific Greater White-fronted Geese (A. a. frontalis), hereafter Pacific Geese. The first step of discriminant function analysis created models to differentiate Tule Geese from the Pacific Geese. Bivariate stepwise discriminant function models consisting of only two measurements correctly classified 92% of males (bill height, bill width) and 96% of females (bill height, culmen) of these subspecies. The second step of discriminant function analysis compared a small population of Pacific Geese from the Bristol Bay Lowlands (BBL) of southwestern Alaska with the large population of Pacific Geese that breed on the Yukon-Kuskokwim River Delta (YKD) of westcentral Alaska. We developed models with three (culmen, diagonal tarsus, midtoe) and five (culmen, diagonal tarsus, midtoe, total tarsus, bill height) measurements from stepwise discriminant function analyses to correctly classify 72% of males and 74% of females of these populations. Thus, morphology of Tule Geese differed highly significantly from Pacific Geese, as expected but differences between populations from the BBL and YKD areas were also significant. Morphometric analyses as these provided supporting evidence for clinal variation in populations of Greater White-fronted Geese. They also underscore a need for further studies of differences among North American populations of Greater White-fronted Geese to resolve classification and to allow formulation of subpopulation/subspecies management strategies.

Condor↗
USGS1995

Waterbird predation on fish in western Lake Erie: a bioenergetics model application

To better understand the role of piscivorous waterbirds in the food web of western Lake Erie, we applied a bioenergetics model to determine their total fish consumption, The important nesting species included the Herring Gull (Larus argentatus), Ring-billed Gull (L. delawarensis), Double-crested Cormorant (Phalacrocorax auritus), Great Blue Heron (Ardea herodias), Black-crowned Night-Heron (Nycticorax nycticorax), and Great Egret (Casmerodius albus). The impact of migrant waterbirds, including the Red-breasted Merganser (Mergus serrator), on western Lake Erie fish biomass was also considered in the analysis. According to the modeling results, during the early 1990s, piscivorous waterbirds consumed 13,368 tonnes of fish from western Lake Erie each year. This tonnage was equivalent to 15.2% of the prey fish biomass needed to support the walleye (Stizostedion vitreum) population in western Lake Erie during a single growing season. The model application was useful in quantifying energy flow between birds and fish in a large lake ecosystem.

Condor↗
USGS1995

Colony differences in response to trapping in roseate terns

Both members of seabird pairs are normally required to fledge young. Seabirds that nest in sites accessible to predators usually have one parent in attendance during the egg/chick phase. Time devoted to foraging can vary with individual skill and age, prey availability and abundance (Seamy 1978), and distance to foraging grounds (Safina 1990). Although average skill of similar-aged individuals should not vary from colony to colony (Ryder 1980), prey availability and abundance, and spatial distribution of foraging grounds may vary. Thus, the percent of time both members of a pair are present at the nest site may vary in different colonies. In this paper, we examine parental behavior in response to trapping in Roseate Terns (Sterna dougallii) nesting in three of the six major colonies in the northeastern United States: Cedar Beach, New York, Falkner Island, Connecticut; and Bird Island, Massachusetts. Roseate Terns were listed on the United States? Endangered Species List in 1987. We were interested in differences among colonies in how often both parents were present, how soon a mate returned to the nest if one parent was temporarily removed, how soon a trapped bird returned to the nest after release, and the time during which the nest was left unguarded. We feel it is important to recognize and make management decisions based on colony differences where they exist. Our study follows directly from earlier work at Cedar Beach on trapping vulnerability of Common Terns (Sterna hirundo) and Roseate Terns. Nisbet reported that Roseate Terns at Bird Island required about three hours to return to the nest after trapping.

Condor↗
USGS1995

Use of implanted satellite transmitters to locate Spectacled Eiders at-sea

Population estimates of Spectacled Eiders ( Somateria fischeri ) on the Yukon-Kuskokwim Delta (YKD), Alaska, suggest that by 1992 the number of birds on this major nesting area had declined to 1,721 pairs, 4% of that estimated in the 1970s (Stehn st al 1993). Consequently, Spectacled Eiders were listed as threatened under the Endangered Species Act. As nesting habitats for this species are believed to have changed little over the past 100 years, hypotheses concerning the cause of this decline include factors away from nesting areas. The non-nesting distribution of this eider is unknown, but birds are believed to molt and winter in the Bering and Chukchi seas (Dau and Kistchinski 1977). Systematic aerial surveys to locate areas where birds concentrate are expensive because of the vast area to be surveyed and dangerous because of restricted daylight and extreme weather conditions. Surveys from ships along the ice margin in the Bering Sea failed to locate concentrations of birds (Irving et al 1968, Everett et al 1989). We initiated a study to determine if at-sea areas used by Spectacled Eiders could be identified using satellite telemetry.

Alaska↗
USGS1995

Comparison of condition indices in migratory passerines at a stopover site in coastal Louisiana

We evaluated the utility of four nondestructive condition indices—body mass, body mass scaled by wing chord length, fat scoring, and total body electrical conductivity method (TOBEC)—as predictors of lipid levels in migrating Wood Thrushes ( Hylocichla mustelina ), Swainson's Thrushes ( Catharus ustulatus ), and Summer Tanagers ( Piranga rubra ). The Red-winged Blackbird ( Agelaius phoeniceus ), a winter resident, was examined for comparative purposes. In addition, we examined differences among species in relationships of total body lipids and condition indices. Body mass was the best index of lipid levels, explaining 36%-82% of the variation in total body lipids in all four species. The relative contributions of the other indices to the prediction of lipid mass varied among species although TOBEC was selected for inclusion in each regression equation. For two species, equations including TOBEC measurements had lower errors in lipid prediction than equations only using the other nondestructive indices. Errors in lipid prediction were large for all the regression equations based on condition indices. In many cases it will be necessary to develop species-specific equations to predict lipid levels with condition indices.

Louisiana↗
USGS1994

Age, habitat and tide effects on feeding activity of Emperor Geese during Autumn migration

I studied feeding activity of Emperor Geese ( Chen canagica ) on the Alaska Peninsula during autumn migration, 1991. Scan samples were used to estimate the proportion of birds feeding in flocks as a measure of feeding intensity. Most geese fed during low tides and roosted during high tides. However, flocks with disproportionately more juveniles continued to feed during high tides in either blue mussel ( Mytilus edulis ) beds (during relatively low high tides) or in vegetated habitats. Feeding intensity was higher in mussel habitats than in mud/sand or vegetated habitats, and juveniles fed more than adults. Juvenile geese probably have greater nutritional needs than adults, and feeding during high tide may represent their attempt to satisfy these disproportionate demands. Vegetated habitats may be used when high value bivalve prey are unavailable due to tidal inundation.

Alaska↗
USGS1994

Timing of breeding and molting in six species of Hawaiian honeycreepers

The timing of breeding and molting was studied in six species of Hawaiian honeycreepers with differing food habits on the Island of Hawaii. The availability of nectar was highly seasonal, whereas insect abundance was relatively constant throughout the year. All six species of honeycreeper had extended breeding and molting periods with peak breeding between April and July and peak molting in August. Breeding and molting periods for Apapane (Himatione sanguinea) and Iiwi (Vestiaria coccinea), two nectarivorous species, were shorter than those for the more insectivorous Common Amakihi (Hemignathus virens), Hawaii Creeper (Oreomystis mana), Akepa (Loxops coccineus), and Akiapolaau (Hemignathus munroi). Missing or growing flight feathers and either a brood patch or enlarged cloacal protuberance occurred simultaneously in only 3.2% of 2.786 adult birds examined. Although overlap of breeding and molting was rare, some individuals may have been able to allocate energy resources to both activities because of low clutch size, extended brooding of young, and a low rate of molting.

Condor↗
USGS1994

Variation in body mass of wild canvasback and redhead ducklings

We assessed variation in body mass of ducklings in single- and mixed-species broods of wild Canvasbacks (Aythya valisineria) and Redheads (Aythya americana) 20-50 days old. Body mass of canvasback ducklings was not affected by year and season (early vs. late hatch date) despite changes in water conditions. Mean body mass of male and female Canvasbacks did not differ in Class IIA but did differ in older age classes. Within-brood differences in body mass tended to be higher in Class IIA ducklings (6-7% of mean body mass for Canvasbacks, 9-11% in Redheads) and generally declined to 4-6% in Class IIC and older ducklings. Some within-brood differences were as high as 20-30% of mean body mass. Tests to assess sources of within-brood variation (age, sex, and season) in body mass for Canvasbacks were inconclusive. Variation within broods was generally less than that among broods for both Canvasbacks and Redheads. The lack of differences in duckling body mass between single- and mixed-species broods for any age class, sex, or species suggests that mass was not affected by interspecific brood parasitism.

Condor↗
USGS1994

Residency patterns of migrating sandpipers at a midcontinental stopover

Arctic-nesting shorebirds require several refueling stops during their long migrations between breeding grounds and Central and South American wintering areas. The protection of stopover habitats for transcontinental migrants depends on whether birds fly long distances between a few select sites or fly short distances and stop at several wetlands. Although the Great Plains historically provided a vast array of wetlands for use by migrants, wetland loss and conversion have reduced the availability of stopover sites in recent decades. In this study, we examined (1) residency periods, (2) fat dynamics, and (3) migration chronology of two shorebird species, the Semipalmated Sandpiper ( Calidris pusilla ) and White-rumped Sandpiper ( C. fuscicollis ) at Quivira National Wildlife Refuge (NWR), Kansas. Semipalmated Sandpipers had prolonged periods of species residency with overlapping arrivals and departures. Individual residency periods were highly variable and were unrelated to lipid reserves upon arrival. In contrast, White-rumped Sandpipers arrived and departed more synchronously. Birds that arrived in poor condition stayed longer than those with more body fat in 1991, but not in 1992. Wind direction did not influence patterns of departures of either species. We hypothesize that Semipalmated Sandpipers are ecologically eurytopic when migrating across the Great Plains in the spring. Highly variable patterns in arrival, residency, and lipid levels indicate that spring migration of this species is relaxed and opportunistic. White-rumped Sandpipers showed a pattern of reduced flexibility. Flight range estimates suggest that most birds require intermediate stopovers before reaching the breeding grounds. Interior wetlands appear to function as migration stopovers rather than staging areas for shorebirds.

The Condor↗
USGS1994

Geographic variation in Yellow-headed Blackbirds from the northern Great Plains

We assessed geographic variability in morphology among Yellow-headed Blackbirds ( Xanthocephalus xanthocephalus ) collected from breeding populations in Minnesota, North Dakota, and South Dakota in the United States and Alberta, Manitoba, and Saskatchewan in Canada during spring. Both male and female Yellow-headed Blackbirds tended to be larger in the more northern breeding populations. Males collected in Manitoba and southeast Saskatchewan tended to be more like populations from the United States, whereas other populations in Saskatchewan and Alberta populations were morphologically similar to each other. For females, however, only the Manitoba population was similar to the U. S. populations, and the females from the southeastern Saskatchewan were similar to other Saskatchewan birds. Southeastern Saskatchewan appears to represent a transitional region between northwestern and southeastern breeding populations of Yellow-headed Blackbirds.

The Condor↗