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Journal Articles: River Deltas and Birds

Articles  :   Geology  |   Ecosystems  |   Climate Change  |   Sea Level Rise  |   Fauna  |   Birds  |   Fish

Andres, B. A. (1994). "Coastal Zone Use by Postbreeding Shorebirds in Northern Alaska." Journal of Wildlife Management 58(2): 206-213.

Knowledge of shorebird habitat requirements along the Arctic coast of Alaska is crucial to assess potential impacts of oil development. Therefore, I studied abundance and use of habitat by postbreeding shorebirds migrating through the coastal zone of the Colville River delta. Unvegetated silt barrens and vegetated and partially vegetated saltmarshes were surveyed for shorebirds during 1987 and 1988. I recorded 18 species of which 5 species constituted 90% of 32,639 individuals observed. Dunlins (Calidris alpina) dominated observations (59% of all individuals). Across years and habitats, 150 birds/km2 were present in the delta coastal zone. Density of dunlins and sanderlings (C. alba) were higher (P less-than-or-equal-to 0.025) on shoreline silt barrens whereas densities of all other species were equitably distributed among silt barrens and saltmarshes (P > 0.05). Shorebirds, other than dunlins and sanderlings, were positively associated (P less-than-or-equal-to 0.01) with wet, sparsely vegetated saltmarshes. No other site surveyed in northern Alaska hosted as many dunlins as the Colville River delta. Migrating shorebirds using coastal habitats, dunlins in particular, could be adversely affected by coastal oil development.

Barras, S. C. and J. A. Kadlec (2000). "Abiotic predictors of avian botulism outbreaks in Utah." Wildlife Society Bulletin 28(3): 724-729.

Avian botulism is a toxicosis responsible for large outbreaks in wild waterfowl and wading birds. The toxin is produced by the bacterium Clostridium botulinum type C. We gathered existing climatological and streamflow data for the Bear River Delta of northeastern Utah to determine effects of environmental factors on probability of occurrence of an avian botulism outbreak. We built a logistic regression model using weather variables and streamflow amounts for 28 years, with a response variable if an outbreak occurred during each year. Winter-summer precipitation amounts and summer streamflow were predictors of outbreak probability (P<0.001). Outbreaks were more likely to occur during years of high winter-summer precipitation and high Bear River flows during summer. We concluded that these outbreak predictors may contribute to water-level fluctuations in managed wetland units, associated previously with outbreaks in this and other systems.

Bishop, M. A. and N. Warnock (1998). "Migration of Western Sandpipers: Links between their Alaskan stopover areas and breeding grounds." Wilson Bulletin 110(4): 457-462.

Thirty-two radiomarked Western Sandpipers (Calidris mauri), tagged in California and Washington, were relocated at stopover and breeding sites north and west of the Copper River Delta, Alaska. At Cook Inlet, Alaska, seven of the nine relocated birds were at Redoubt and Kachemak bays. Only 1 of the 17 birds relocated on the Yukon-Kuskokwim Delta had been previously detected at Cook Inlet. Detections of birds in western Alaska provide evidence that the Yukon-Kuskokwim Delta is the final breeding destination for many of the birds migrating through San Francisco and other Pacific Coast areas. The Mulchatna River area, 325 km southeast of the Yukon-Kuskokwim Delta, may support a breeding population of Western Sandpipers.

Bishop, M. A., P. M. Meyers, et al. (2000). "A method to estimate migrant shorebird numbers on the Copper River Delta, Alaska." Journal of Field Ornithology 71(4): 627-637.

We estimated the: annual population of Western Sandpipers (Calidras mauri) and Dunlin ( Calidris alpina pacifica) stopping over on the Copper River Delta during peak spring migration 1992-1995. Our calculations required four components: total daily shorebird numbers, the daily proportion of each species, average length of stay, and the detection probability. For the 21-d period 26 April-16 May, annual population estimates for Western Sandpiper ranged from 1.2-4.1 million birds per year. Dunlin estimates for this same period ranged from 0.3-0.9 million. For both species, numbers were highest in 1993 and lowest in 1994. Power analysis determined that 15 yr of aerial surveys are needed to detect a 10% decline in Western Sandpiper numbers. Based on the proportion of birds in the Pacific Flyway stopping over on the Copper River Delta, we estimated the Western Sandpiper Pacific Flyway population was >2.8 million in 1992 and >4.3 million in 1995. These data indicate that the Copper River Delta continues to support the largest spring concentration of shorebirds in the Western Hemisphere.

Butler, R. W. (1999). "Winter abundance and distribution of shorebirds and songbirds on farmlands on the Fraser River delta, British Columbia, 1989-1991." Canadian Field-Naturalist 113(3): 390-395.

The winter distribution of common shorebirds and songbirds in farmlands on the Fraser River delta, British Columbia, is described for 1989-1991. Most Dunlin (Calidris alpina) and Black-bellied Plovers (Pluvialis squatarola) roosted in large flocks (median=6450 birds) on beaches during high tides. Smaller flocks (median=507 birds) that flew to farmlands sealed in ploughed fields, turf grass and pasture within 2 km of Boundary Bay. Dunlin and Black-bellied Plovers that flew to farmlands mostly foraged there between November and March. The seasonal use of farmlands by Dunlins is probably a trade off between food energy requirements and predation risk from falcons. Forty-five species of songbirds were recorded in farmland hedgerows. Song Sparrow (Melospiza melodica), American Robin (Turdus migratorius), White-crowned Sparrow (Zonotrichia leucophrys), and European Starling (Sturnus vulgaris) accounted for over two-thirds of all birds recorded. Shrub hedgerows supported 30 species with a mean of 7.9 individuals detected per census stop versus 40 species with a mean of 18.0 individuals per census stop in tree-hedgerows.

Campbell, B. H. (1990). "Factors Affecting the Nesting Success of Dusky Canada Geese, Branta-Canadensis-Occidentalis, on the Copper River Delta, Alaska." Canadian Field-Naturalist 104(4): 567-576.

Habitat availability, use by nesting geese, and nest fate were sampled between 1982-1986 to determine how changes in habitat have affected the nesting ecology of the Dusky Canada Goose. Shrub communities have displaced much of the mixed grass/forb habitat preferred by geese for nesting. Geese have adjusted to this change and are using shrub habitats in a greater proportion than expected. The distribution of nests in shrub and open levee habitats is related to spring phenology with more nests occurring in shrub habitats in early springs. Nest success has declined since the late 1970s with predation by Brown Bears, canids, and predaceous sea birds being the primary cause of nest losses. Nest predation rates are also related to spring phenology with greater losses occurring during late springs. However, the magnitude of nest predation by the three major predators varied annually independent of spring phenology. Brown Bears were consistently responsible for about half the nest destruction while canids and predaceous seabirds were responsible for approximately 20% and 16%, respectively. No association between habitat type and overall level of nest destruction or nest destruction by specific predator was observed. While canids and avian predators may have preferences for certain habitats for foraging, the dominance of the opportunistic brown bear, which appears to have no preference as a nest predator, probably masks these preferences. Poor nest success is likely to continue unless predators are managed to benefit the Dusky Canada Goose.

Custer, T. W. and W. L. Hohman (1994). "Trace-Elements in Canvasbacks (Aythya-Valisineria) Wintering in Louisiana, USA, 1987-1988." Environmental Pollution 84(3): 253-259.

We determined trace element concentrations in livers of canvasbacks (Aythya valisineria) collected at Catahoula Lake and the Mississippi River Delta, Louisiana during, the winter of 1987-88. Forty percent of canvasbacks wintering at Lake Catahoula had elevated concentrations of lead (>6.7 mug g-1 dry weight) in the liver; 33% had concentrations consistent with lead intoxication (>26.7 mug g-1). Based on the number of canvasbacks that winter at Lake Catahoula and the frequency of lead exposure there, more than 5% of the continental population of canvasbacks may be exposed to lead at Lake Catahoula alone. Lead concentrations in livers differed among months and were higher in males than females, but were not different in adults and immatures. Concentrations of selenium and mercury in livers of females differed among months but not by age or location. Cadmium concentrations in livers differed by age, location and month of collection, but not by sex. Frequencies and concentrations of trace elements not commonly associated with adverse effects on avian species (aluminum, arsenic, copper, iron, magnesium, manganese, nickel, silver, vanadium and zinc) are presented. Except for the elevated concentrations of lead at Catahoula Lake, all trace elements were at background concentrations.

Day, J. W., G. P. Shaffer, et al. (2000). "Pattern and process of land loss in the Mississippi Delta: A spatial and temporal analysis of wetland habitat change." Estuaries 23(4): 425-438.

An earlier investigation (Turner 1997) concluded that most of the coastal wetland loss in Louisiana was caused by the effects of canal dredging, that loss was near zero in the absence of canals, and that land loss had decreased to near zero by the late 1990s. This analysis was based on a 15-min quadrangle (approximately 68,000 ha) scale that is too large to isolate processes responsible for small-scale wetland loss and too small to capture those responsible for large-scale loss. We conducted a further evaluation of the relationship between direct loss due to canal dredging and all other loss from 1933-1990 using a spatial scale of 4,100 ha that accurately captures local land-loss processes. Regressions of other wetland loss on canal area (i.e., direct loss) for the Birdfoot, Terrebonne, and Calcasieu basins were not significant. Positive relationships were found for the Breton (r(2) = 0.675), Barataria (r(2) = 0.47), and Mermentau (r(2) = 0.35) basins, indicating that the extent of canals is significantly related to wetland loss in these basins. A significant negative relationship (r(2) = 0.36) was found for the Atchafalaya coastal basin which had statistically lower loss rates than the other basins as a whole. The Atchafalaya area receives direct inflow of about one third of the Mississippi discharge. When the data were combined for all basins, 9.2% of the variation in other wetland loss was attributable to canals. All significant regressions intercepted the y-axis at positive loss values indicating that some loss occurred in the absence of canals. Wetland loss did not differ significantly from the coast inland or between marsh type. We agree with Turner that canals are an important agent in causing wetland loss in coastal Louisiana, but strongly disagree that they are responsible for the vast majority of this loss. We conclude that wetland loss in the Mississippi delta is an ongoing complex process involving several interacting factors and that efforts to create and restore Louisiana's coastal wetlands must emphasize riverine inputs of freshwater and sediments.

Elliott, J. E., L. K. Wilson, et al. (1997). "Secondary poisoning of birds of prey by the organophosphorus insecticide, phorate." Ecotoxicology 6(4): 219-231.

As a part of a monitoring study, five dead or debilitated bald eagles (Haliaeetus leucocephalus) and a red-tailed hawk (Buteo jamaicensis) from the Fraser River Delta of British Columbia (BC), Canada tested positive for residues of the organophosphorus insecticide, phorate. The first group of three birds was found during January and February 1992, from which two eagles were confirmed to have been poisoned by phorate. The second poisonings took place from December 1993 to March 1994, when three eagles and a hawk were confirmed as phorate poisoned. The brain and plasma cholinesterase results are presented along with data on chemical residue analyses of ingesta, Granular phorate, used in the area to control pests on potatoes and other root crops, appears to have a prolonged half-life similar to carbofuran and fensulfothion, two other granular insecticides associated with secondary mortality of raptors in the Fraser Delta. The soil persistence of phorate combined with a high acute toxicity poses a risk to waterfowl which are attracted to flooded fields in the autumn and winter and, thus, to raptors scavenging on dead waterfowl. The manufacturer has voluntarily withdrawn phorate, marketed as Thimet 15G, from the BC market as a result of the evidence presented here.

Elliott, J. E., I. E. Moul, et al. (1998). "Variable reproductive success of bald eagles on the British Columbia coast." Journal of Wildlife Management 62(2): 518-529.

To determine factors affecting productivity of bald eagles (Haliacctus leucocephalus) nesting near industrial sites in the Strait of Georgia, British Columbia, we compared their reproductive success to sites on the outer Pacific Coast. Mean production (fledged young per occupied territory) over the period 1992-95 was higher at sites in the Strait of Georgia, including the lower Fraser River Valley (1.2) and southeast Vancouver er Island (0.95), compared to subpopulations at putative reference areas at Clayoquot Sound (0.27) on the west coast of Vancouver Island and in northern Johnstone Strait (0.30: P < 0.001). Low breeding success was mainly the result of nest failure when no eggs were laid, or eggs were abandoned during incubation. Food supply apparently was the key factor limiting breeding success. Total lipids measured in nestling plasma samples varied among sites (P < 0.010), and there was a relation between mean plasma lipids and mean annual productivity (r(2) = 0.52, P = 0.043), suggesting that food was Limiting in areas of low productivity: even at successful nests. There were no differences in prey delivery rates to nests in the less productive Barkley Sound (0.56) compared to the more productive Fraser River Delta (1.1). There was, however, a difference in prey composition between the 2 sites (P < 0.001), with more small fish and few er birds and mammals brought to Barkley Sound nests. Mean hatching date was later at nests outside the Strait of Georgia but was not a determinant of productivity because we recorded the latest mean hatching date at Langara Island, a site of seasonal food abundance and fair productivity (0.61).

Fefelov, I. V. (1999). "Transformation of landscapes in the Selenga River delta and changes in the fauna of birds of prey." Russian Journal of Ecology 30(5): 351-353.

Fleskes, J. P., R. L. Jarvis, et al. (2002). "Distribution and movements of female northern pintails radiotagged in San Joaquin Valley, California." Journal of Wildlife Management 66(1): 138-152.

To improve understanding of northern pintail (Anas acuta) distribution in central California (CCA), we radiotagged 191 Hatch-Year (HY) and 228 After-Hatch-Year female northern pintails during late August-ear-IN, October, 1991-1993, in the San Joaquin Valley (SJV) and studied their movements through March each year. Nearly all (94.3%) wintered in CCA, but 5.7% went to southern California, Mexico, Or unknown areas; all that that went south left before hunting season. Of the 395 radiotagged pintails that wintered in CCA, 83% flew from the SJV north to other CCA areas (i.e., Sacramento Valley [SACV], Sacramento-San Joaquin River Delta [Delta], Suisun Marsh, San Francisco Bay) during September-January; most went during December. Movements coincided with Start of hunting seasons and were related to pintail age, mass, capture location, studs year, and weather. Among pintails with less than average mass, AHY individuals tended to leave the SJV earlier than HY individuals. Weekly distribution was similar among capture locations and years but a greater percentage of pintails radiotagged in Tulare Basin (south part of SJV) were known to have (10.3% vs. 0.9%) or probably (13.8% vs. 4.6%) wintered south of CCA than pintails radiotagged in northern SJV areas (i.e,, Grassland Ecological Area [EA] and Mendota Wildlife Area [WA]). Also, a greater percentage of SJV pintails went to other CCA areas before hunting season in the drought year of 1991-1992 than later years (10% vs. 3-5%). The percent of radiotagged pintails from Grassland EA known to have gone south of CCA also was greater during 1991-1992 than later years (2% m 0%), but both the known (19% vs. 4%) and probable (23% v. 12%) percent From Tulare Basin that went south was greatest during 1993-1994, when availability of flooded fields there was lowest. The probability of pintails leaving the SJV as 57% (95% Cl = 8-127%) greater on dabs with than without rain, and more movements per bird out of SJV occurred in years with more rain and fug but fewer days with southerly winds. Movements by pintails and changes in pintail distributions, direct recovery distributions, and harvest rates suggest the disproportionate decline of pintails in Tulare Basin was due to a lower percentage of pintails moving there in fall and a greater percentage or earlier movements north and south out of Tulare Basin. With fewer in Tulare Basin to replace Grasslands FA pintails going north in December, pintail abundance in the northern SJV declined during late winter. Changes in movement patterns correspond to habitat loss in Tulare Basin and increased habitats in SACV and western mainland Mexico. Habitat improvements, especially in Tulare Basin, that increase food, sanctuary, and winter survival would probably help restore pintails throughout the SJV.

Garcia-Hernandez, J., E. P. Glenn, et al. (2000). "Bioaccumulation of selenium (Se) in the Cienega de Santa Clara wetland, Sonora, Mexico." Ecotoxicology and Environmental Safety 46(3): 298-304.

The Cienega de Santa Clara, on the east side of the Colorado River delta, is a brackish wetland supported by agricultural drainage water front the United States that provides habitat for endangered fish and bird species, Bioaccumulation of selenium has created toxicity problems for wildlife in similar wetlands in the United States. This is the first selenium survey in the Cienega de Santa Clara. Ten sites mere selected to collect water (dissolved), sediments (total), plants, invertebrates, and fish. Samples mere collected from October 1996 to March 1997, Selenium was detected in all samples. Concentrations in Rater ranged from 5 to 19 mu g/L and increased along a salinity gradient. Although water levels of selenium exceeded EPA criterion for protection of wildlife, Levels in sediments (0.8-1.8 mg/kg), aquatic plants (0.03-0.17 mg/kg), and fish (2.5-5.1 mg/kg whole body, dry wt) did not exceed USFWS recommended levels, It is concluded from this studs that the levels of selenium in water did not affect the overall health of the fish sampled. Therefore, it is important to maintain or improve the mater quality entering this wetland to continue to have normal levels of Se in the food chain components. (C) 2000 Academic Press.

Garcia-Hernandez, J., K. A. King, et al. (2001). "Selenium, selected inorganic elements, and organochlorine pesticides in bottom material and biota from the Colorado River delta." Journal of Arid Environments 49(1): 65-89.

Concentrations of selenium (Se) in bottom material ranged from 0.6 to 5.0 mug g(-1), and from 0.5 to 18.3 mug g(-1) in biota; 23% of samples exceeded the toxic threshold. Concentrations of DDE in biota exceeded the toxic threshold in 30% of the samples. Greater concentrations of selenium in biota were found at sites with strongly reducing conditions, no output, alternating periods of drying and flooding or dredging activities, and at sites that received,,vater directly from the Colorado River. The smallest Se concentrations in biota were found at sites where an outflow and exposure or physical disturbance of the bottom material were uncommon. (C) 2001 Academic Press.

Garcia-Hernandez, J., O. Hinojosa-Huerta, et al. (2001). "Willow flycatcher (Empidonax traillii) surveys in the Colorado River delta: implications for management." Journal of Arid Environments 49(1): 161-169.

A subspecies of willow flycatcher, the south-western willow flycatcher, has become endangered in the U.S. The objective of this study was to determine the presence/absence of this subspecies in the Colorado River delta. Surveys were conducted in June-July 1999 and in May-June 2000. We detected a total of 50 birds, most likely south-western willow flycatchers, from May to June and none in July. It appears that the birds found in the delta were migrants. It is important to restore the intensively used stopover sites for the recovery of the subspecies. Additionally, we postulate a migratory route throughout the estuaries of Sonora. (C) 2001 Academic Press.

Genovart, M., L. Jover, et al. (2003). "Offspring sex ratios in subcolonies of Audouin's gull, Larus audouinii, with differential breeding performance." Canadian Journal of Zoology-Revue Canadienne De Zoologie 81(5): 905-910.

At the Ebro River delta colony in the western Mediterranean Sea, Audouin's gull, Larus audouinii, breeds in discrete aggregations called subcolonies, which showed strong differences in breeding parameters such as egg volume or breeding success. Egg parameters (such as size of both eggs and clutches) are strongly influenced by food availability. As all subcolonies are in the same area, differences in egg parameters might reflect different individuals' foraging efficiency. We measured mean clutch volumes in different subcolonies and chose those subcolonies that showed the greatest differences in this measure, which should indicate differences in parental body condition. Between these subcolonies we would expect, in turn, differences in offspring sex ratios. We took blood samples at hatching and fledging from chicks at these subcolonies and compared offspring sex ratios by means of molecular sexing. The proportions of young breeders differed between these subcolonies, and the subcolony with the greater proportion of young breeders produced smaller eggs and had lower breeding success. However, we did not detect any bias in progeny sex ratio, which probably indicates that if parental condition is not extremely reduced, selective pressures are insufficient to overcome the constraints imposed by Mendelian segregation of chromosomes.

Glenn, E. P., F. Zamora-Arroyo, et al. (2001). "Ecology and conservation biology of the Colorado River delta, Mexico." Journal of Arid Environments 49(1): 5-15.

The Colorado River delta in Mexico has been partially revegetated following 20 years of water flows from the United States. Lake Powell, the last major impoundment built on the river, filled in 1981. Since then, flood flows in the main channel of the river have occurred in El Nino cycles, and have returned native trees and other vegetation to the riparian corridor. This vegetation provides a migration route for endangered southwestern willow flycatchers (Empidonax traillii) and other migratory birds moving from Mexico to the United States for summer nesting. Agricultural drain water from the Wellton-Mohawk Irrigation District conveyed to the delta since 1977 has created Cienega de Santa Clara, a 4200-ha Typha domengensis marsh containing the largest remaining population of the endangered Yuma clapper rail (Rallus longirostris yumanensis), plus numerous species of migratory and resident waterfowl. Populations in the marine part of the delta have been severely affected by the lack of river flow, but some species have responded positively to renewed flows. Currently, there are 170,000 ha of natural areas in the lower delta in Mexico, containing riparian, wetland and intertidal habitats. Much of this land as well as the adjacent marine zone is protected in the Biosphere Reserve of the Upper Gulf of California and Colorado River Delta. Natural resource managers, scientists and non-governmental environmental groups in Mexico and the United States are exploring conservation measures that can provide water and protection for these areas for the future. (C) 2001 Academic Press.

Henson, P. and J. A. Cooper (1993). "Trumpeter Swan Incubation in Areas of Differing Food Quality." Journal of Wildlife Management 57(4): 709-716.

intraspecific comparisons along geographic gradients are useful in evaluating the adaptive significance of avian incubation behavior. Incubation constancy in northern-breeding Anserinae is correlated with breeding success, and trumpeter swan (Cygnus buccinator) populations vary in growth and other population characteristics. Thus, we compared incubation constancy and other behaviors of female trumpeter swans nesting in 2 areas suspected to differ in food quality and availability: the Copper River Delta, Alaska (1988-89), and the Tristate Region of Idaho, Montana, and Wyoming (1991). Alaskan females fed on abundant emergent macrophytes, whereas Tristate females fed on submerged macrophytes that may require more search and handling time. Alaskan swans took shorter (P = 0.001) incubation recesses and maintained higher (P = 0.017) incubation constancy than Tristate birds. Our data are consistent with the hypothesis that the Tristate Region is lower quality swan habitat than that in Alaska because it appears to lack food resources necessary for female swans to maintain a high incubation constancy in an area with a short and harsh breeding season.

Higuchi, H., J. P. Pierre, et al. (2004). "Using a remote technology in conservation: Satellite tracking White-naped Cranes in Russia and Asia." Conservation Biology 18(1): 136-147.

We investigated the application of satellite tracking to the conservation of cranes and other waterbirds and the necessity of international cooperation in the conservation of migratory species. Using satellite tracking, we followed 11 White-naped Cranes (Grus vipio) on migration from their breeding grounds in eastern Russia to their wintering grounds in China and Japan. From 1991 to 1993, we captured cranes with the aid of helicopters and attached satellite transmitters (platform transmitter terminals) to captured birds via a harness system. We tracked cranes for 156 days on average, across 2558 km, and obtained an average of 339 locations per crane. Cranes migrated over 8-90 days. During migration, birds spent 1-30 days at 4-12 rest sites. Cranes wintered at two main sites: Poyang Lake, China, and Izumi, Japan. All seven cranes migrating to the Poyang Lake area rested at the Yellow River delta-Bohai Bay, China, and all three traveling to Izumi rested in the Demilitarized Zone on the Korean Peninsula. Other important rest sites were marshes around the Wulagai River, Huainan, Hu-Lun Lake, Linyi, Tangshan, the Three Rivers (Sanjiang) Plain, Tianjin, and the Xar Moron River, all in China, and Lake Khanka-Xinghai at the border of China and Russia. The habitats resting cranes used most frequently were plains, including upland areas, marshes, and rivers. Although nature reserves exist at the two main wintering sites of Poyang Lake and Izumi, rest sites used by cranes were poorly protected. Even when areas used by cranes for resting or wintering were included in nature reserves, reserves were threatened by human encroachment and development. To ensure that cranes can continue to migrate successfully, it is crucial that the establishment of reserves continues at important rest areas and that the areas covered by reserves at wintering sites be extended to include more of the areas utilized by cranes. Also, development and human disturbance should be minimized in reserve areas. Because long-distance migrant birds, including cranes, range over such large areas, conservation of these organisms and their habitats necessitates multinational communication and cooperation.

Hinojosa-Huerta, O., S. DeStefano, et al. (2002). "Evaluation of call-response surveys for monitoring breeding Yuma Clapper Rails (Rallus longirostris yumanensis)." Journal of Field Ornithology 73(2): 151-155.

During March-June 2000 we evaluated the use of call-response surveys to monitor breeding Yuma Clapper Rails (Rallus longirostris yumanensis) at the Cienega de Santa Clara, Colorado River Delta, Sonora, Mexico. We assessed the effect that time of day, stage of breeding season, and number of survey periods had on the average number of rails detected at a station. Conducting call-response surveys resulted in a significant increase in the number of detected rails and reduced the coefficient of variation of the average number or rails per station, which increases the statistical power to detect population trends. Using this technique also appears to reduce the variation of rates of responses by rails through the breeding season when compared to passive listening. There was no difference between the number of rails detected during morning and afternoon surveys. The established protocol developed by the U.S. Fish and Wildlife Service for Yuma Clapper Rail surveys is adequate for monitoring, and it should continue to be implemented on a yearly basis at the Cienega de Santa Clara and other wetlands of the Colorado River Delta in Mexico.

Hohman, W. L. (1993). "Body-Composition of Wintering Canvasbacks in Louisiana - Dominance and Survival Implications." Condor 95(2): 377-387.

I studied effects of sex, age, and month on body mass and composition of Canvasbacks (Aythya valisineria) at Catahoula Lake (CL) and the Mississippi River Delta (MRD), Louisiana, in winter 1987-1988. Size-adjusted body mass and fat varied by age, month, and site. Fat levels in immatures were greater at MRD than at CL, but changed similarly at both sites. Adults at MRD were also fatter than those at CL in early winter, especially in December, but fat levels of all birds increased from early to late winter and were equivalent by late winter. Body protein adjusted for structural size varied by age, month, and site, and sex, month, and site. Protein levels by site were higher in adults and males than in immatures and females, but sex- and age-related differences averaged < 11 g (5%). Changes in size-adjusted leg muscle protein (index of feeding activity) and body fat were positively associated. This relation (my measure of feeding efficiency) was not affected by sex or age of Canvasbacks, implying that all birds at CL or MRD fed at similar efficiencies by month. At both sites, females were fatter than males; thus, although males were larger and potentially dominant to females, it appears that females were not disadvantaged in their acquisition of nutrients during the year of study. Body mass of CL and MRD birds in winter 1987-1988 was greater than that of Canvasbacks wintering elsewhere. If overwinter and annual survival of Canvasbacks are related to their relative body mass during winter, then survival probabilities of CL and MRD birds may be high compared to other wintering populations.

Iverson, G. C., S. E. Warnock, et al. (1996). "Spring migration of Western Sandpipers along the Pacific Coast of North America: A telemetry study." Condor 98(1): 10-21.

We studied the migratory movements of radio-equipped Western Sandpipers (Calidris mauri) along a 4,000 km stretch of the west coast of North America from California to Alaska during the 1992 spring migration. A total of 77 shorebirds were radio-tagged at San Francisco Bay, CA; Bolinas Lagoon, CA; Fraser River Delta, British Columbia; and the Stikine River Delta, AK. Daily aerial and ground monitoring from mid-April to late May at banding sites as well as the Copper River Delta provided data on length of stay of individual shorebirds and migration times between study areas. Fifty-eight shorebirds were detected beyond banding sites for a 74% net relocation rate. The proportion of birds detected along the migration route increased with latitude: Grays Harbor, WA (3.4%); Fraser River, British Columbia (8.6%); Stikine River, AK (28.6%); and Copper River, AK (62.3%). Length of stay averaged three days per site. We failed to detect differences in length of stay among sites or between sexes. A condition index calculated as body mass standardized for body size was a poor indicator of length of stay at a site or migration time among sites. An estimated 26% of radio-equipped birds were never relocated suggesting that migrant birds use smaller dispersed wetlands as well as the major intertidal wetland complexes we studied. We conclude that most spring migrant Western Sandpipers use a short-flight hopping migration strategy rather than a few sustained long flights. The short-flight strategy emphasizes the importance of maintaining a continuous complex of intertidal wetland habitats along the migration route to ensure shorebird conservation.

Johnson, S. R. (1995). "Immigration in a small population of snow geese." Auk 112(3): 731-736.

The Lesser Snow Goose (Chen caerulescens caerulescens) colony on Howe Island, near Prudhoe Bay, Alaska, is the only established nesting colony of this species in the United States. A study was initiated to follow the dynamics of this small population in 1980 when it became clear that oil development would proceed near the nesting colony and in nearby brood-rearing areas. Virtually all brood-rearing Snow Geese in the study area were banded in late July of 1980 through 1993 to determine return rates of banded birds and to determine whether immigration contributed significantly to the maintenance and growth of the population. This was a critical question if, in the future, a local catastrophe (e.g. foul cholera, oil spill) were to affect most or all of the birds in this small population. During this 15-year study, the Snow Goose population expanded from 39 to 412 nesting pairs. Based on mark-recapture data from the banding programs, the immigration rates for females and males are estimated to be 12.8 +/- SD of 4.39% and 60.7 +/- 12.85%, respectively. Exceptionally high immigration rates for males were recorded in 1990 and 1993, when large numbers of two- and three-year-old females (banded as goslings) returned with unbanded mates from other populations. Many females apparently immigrated when they were juveniles. The origins of immigrants is still unclear because of limited banding at neighboring colonies. Resightings of neck-banded Howe Island geese indicate emigration of primarily males to Wrangel Island, Russia, and Banks Island and the Anderson River Delta, Northwest Territories, Canada.

Johnson, S. R., J. O. Schieck, et al. (1995). "Neck Band Loss Rates for Lesser Snow Geese." Journal of Wildlife Management 59(4): 747-752.

Band loss is often assumed to be negligible when resightings of neck-banded birds are used to estimate population parameters. Neck band loss rates (M, 0.47; F, 0.17) for lesser snow geese (Chen caerulescens caerulescens) were estimated for 1981-90 in the Sagavanirktok River Delta, Alaska. Neck band loss was substantial and comparable with or higher than rates reported for several Canada goose (Branta canadensis) populations. Nearly 60% of neck bands lost were found broken near nest sites, indicating that the majority of bands was lost when birds returned to the Arctic to breed, rather than during migration or winter. Annual neck band loss rates increased (P < 0.001) with neck band age, and rates were higher (P < 0.001) for males than for females. Loss rates of replacement neck bands were higher than for first neck bands (P < 0.01). Maximum neck band retention by males and females was 3 and 7 years, respectively, even though some snow geese survived for the entire 10-year study. Neck band resighting data should not be used to estimate demographic traits, such as survival, without considering neck band loss.

Johnson, S. R. (1998). "Distribution and movements of brood-rearing lesser snow geese in relation to petroleum development in Arctic Alaska." Arctic 51(4): 336-344.

Environmental scientists were concerned that construction of the Endicott Project in the outer Sagavanirktok River delta, east of Prudhoe Bay, Alaska, would obstruct brood-rearing movements of Alaska' s largest established nesting population of lesser snow geese (Chen caerulescens caerulescens). During 1980-84, prior to the Endicott Project, the distribution of snow goose flocks during the brood-rearing period was generally less than 5 km from the coast and 15 km from the nesting colony. Prior to development, the average distance between brood-oaring areas used during consecutive years by individual banded birds was 4.7 +/- 2.9 km (mean +/- s.d.). After development commenced during winter 1984-85, the distribution of brood-rearing flocks expanded inland as far as 9 km and eastward as far as 32 km from the nesting colony. The average distance between brood-rearing areas used during consecutive years by individual banded birds was 8.0 +/- 7.5 km. The proportion of brood-rearing snow geese captured on the east side of the Endicott Road and Causeway (east of the nesting colony) during the post-construction years (1985-93) was not significantly different from the proportion using the same area before construction (1980-84). The hypothesis that the Endicott Road and Causeway obstructed eastward movements of brood-rearing snow geese can be rejected.

Johnson, O. W., C. D. Adler, et al. (2004). "Radio-tagged Pacific Golden-Plovers: Further insight concerning the Hawaii-Alaska migratory link." Wilson Bulletin 116(2): 158-162.

We radio-tagged 55 Pacific Golden-Plovers (Pluvialis fulva) in spring 2001-2003 on wintering grounds in Hawaii. Following their northward migration (most birds deserted winter territories in late April), we relocated 15 golden-plovers in three regions of Alaska: Copper River Delta, King Salmon, and Kotzebue. One individual made the transpacific flight from Oahu to the Alaska Peninsula in a minimum time of 70 hr at a minimum flight speed of 56 km/hr. Our findings, together with earlier records, indicate a major Hawaii-Alaska migratory connection for this species, and suggest that plovers wintering on Oahu nest throughout the known Alaska breeding range. Post-breeding, 84% of the sample birds returned to Oahu and reoccupied their previous winter territories.

Kanai, Y., M. Ueta, et al. (2002). "Migration routes and important resting areas of Siberian cranes (Grus leucogeranus) between northeastern Siberia and China as revealed by satellite tracking." Biological Conservation 106(3): 339-346.

In 1995 and 1996 thirteen Siberian cranes (Grits leucogeranus) were fitted with satellite transmitters on the breeding grounds in northeastern Siberia. Eleven of these 13 birds were successfully satellite tracked, and five of these I I provided complete migratory information from their breeding grounds in Yakutia, Siberia, to their wintering area at Poyang Lake, in China. Several stopover sites were identified, the most important being in Qiqihar-Baicheng (China), Shuangtaizi River delta (China), and Yellow River delta (China). Birds rested more frequently in Russia than in China, suggesting availability of suitable wetland habitat in Russia and absence of adequate, suitable wetland habitat in China. Wintering habitat in China also faces numerous threats. Habitats utilized by Siberian cranes are also important to other threatened wetland birds that have been satellite-tracked recently. If Siberian crane habitat needs fail to be addressed, this critically endangered species will be further endangered. (C) 2002 Elsevier Science Ltd. All rights reserved.

Nebel, S. and B. J. McCaffery (2003). "Vocalization activity of breeding shorebirds: documentation of its seasonal decline and applications for breeding bird surveys." Canadian Journal of Zoology-Revue Canadienne De Zoologie 81(10): 1702-1708.

We documented vocalization activity of breeding shorebirds at two sites in northern and western Alaska, on the Colville River Delta and on the Yukon - Kuskokwim Delta. At both sites, number of calling individuals decreased throughout the season. Variation in vocalization activity was significantly higher at the Colville River Delta towards the end of the season, while weather variables affected vocalization activity only on the Yukon - Kuskokwim Delta. Our results highlight the importance of timing, weather, and site-specific attributes on number of birds detected. We discuss our findings in the context of different methods to monitor breeding shorebirds.

Ogden, L. J. E., K. A. Hobson, et al. (2004). "Blood isotopic (delta C-13 and delta N-15) turnover and diet-tissue fractionation factors in captive Dunlin (Calidris alpina pacifica)." Auk 121(1): 170-177.

Avian studies are often interpreted using dual (e.g. C-13, N-15) isotope models, assuming turnover of both isotopes occur at similar rates, but only a few studies have quantified turnover rates for more than one of those isotopes simultaneously. To test the generality of previous turnover and fractionation estimates and assumption of synchronous C and N patterns of turnover rates, we captured Dunlin (Calidris alpina pacifica) wintering in the Fraser River Delta, British Columbia, and derived isotopic turnover rates and diet-tissue fractionation factors by experimentally manipulating diet. Birds (n = 15) were initially fed a terrestrially derived diet (mean delta(13)C: -24.7parts per thousand, mean VN: 3.5parts per thousand) for 54 days. A treatment group (n = 11) was then switched to a marine-derived diet (mean delta(13)C: -18.3parts per thousand, mean delta(15)N: 13.7parts per thousand); a control group (n 4) was maintained on the terrestrial diet for a further 59 days. An exponential model described patterns of isotopic turnover for C-13 and N-15, and turnover rates and half-lives of the two isotopes were correlated, confirming the assumption of synchronous patterns of turnover for those isotopes. The half-lives for C-13 and N-15 in Dunlin whole blood were 11.2 +/- 0.8 days and 10.0 +/- 0.6 days, respectively, and are among the lowest values obtained to date for wild birds. Variation in turnover rate among individuals was not related to indices of body condition.

Pearce, J. M., D. Esler, et al. (1998). "Birds of the Indigirka River Delta, Russia: Historical and biogeographic comparisons." Arctic 51(4): 361-370.

We documented the breeding status and relative abundance of all avian species on the coastal portion of the Indigirka River Delta during spring and summer 1993-95. Data on avifaunal composition were then compared to data from adjacent areas from Eastern Siberia to the Chukotka Peninsula to evaluate how species composition changes longitudinally within the arctic and typical tundra zones of northern Russia. We recorded 63 species on the Indigirka River Delta, 37 (58.7%) of which were confirmed breeders during at least one of the three years. Five new species were recorded breeding (Arenaria interpres, Calidris acuminata, Limnodromus scolopaceus, Stercorarius parasiticus, and Asio flammeus), and 13 previously unrecorded species were observed during this study. We also identified several species of rare or threatened status in Russia and North America, including Branta bernicla, Somateria fischeri, Polysticta stelleri, and Rhodostethia rosea. We used parsimony and distance matrix methods to compare the breeding species richness on the Indigirka River Delta to that of six other Russian Arctic areas. Biogeographic comparisons revealed the presence of two clades in the Russian Arctic: the Lena River Delta east to Chaun Delta and the Chukotka Peninsula.

Pearce, J. M., B. J. Pierson, et al. (2000). "A genetic evaluation of morphology used to identify harvested Canada geese." Journal of Wildlife Management 64(3): 863-874.

Using maximum likelihood estimators (in genetic stock identification), we used genetic markers to evaluate the utility of 2 morphological measures (culmen length and plumage color) to correctly identify groups of hunter-harvested dusky (Branta canadensis occidentalis) and dusky-like Canada geese on the wintering grounds within the Pacific Flyway. Significant levels of genetic differentiation were observed across all sampled breeding sites for both nuclear microsatellite loci and mtDNA when analyzed at the sequence level. The ability to discriminate among geese from these sites using genetic markers was further demonstrated using computer simulations. We estimated contributions from the Copper River Delta, the primary breeding area of dusky Canada geese, to groups of hunter-harvested geese classified as dusky Canada geese on the basis of morphology as 50.6 +/- 10.1(SE)% for females and 50.3 +/- 13.0% for males. We also estimated that 16 +/- 8.1% of females classified as dusky Canada geese on the basis of morphology originated from Middleton Island, Alaska; a locale currently managed as a subpopulation of dusky Canada geese, even though the majority of geese from this area possess a unique mtDNA haplotype not found on the Copper River Delta. The use of culmen length and plumage color to identify the origin of breeding populations in the harvest provides conservative criteria for management of dusky Canada geese as individuals of other breeding populations are misassigned as dusky Canada geese and birds of the lighter-plumaged dusky-like group did not appear to originate from breeding sites of the dusky Canada goose. Our analyses demonstrate that genetic markers can accurately estimate the proportion of genetically differentiated areas that comprise an admired group, but they also raise questions about the management scale of Pacific Flyway Canada geese (e.g., at the subspecies or breeding population level) and the use of morphological and genetic characteristics to monitor the harvest of different populations within admired wintering Rocks.

Peterson, C. A., S. L. Lee, et al. (2001). "Scavenging of waterfowl carcasses by birds in agricultural fields of British Columbia." Journal of Field Ornithology 72(1): 150-159.

In the Fraser River Delta, scavenging of poisoned waterfowl by raptors during winter has led to secondary anticholinesterase poisoning. During the winters of 1996 and 1998, we used still and video photography to examine scavenging activity on waterfowl carcasses in agricultural fields. Carcass discovery was rapid for both study years; all but two of 54 carcasses were found within 72 h, and 77.8% were found within 24 h (primarily in the first 12 h after sunrise). Single duck carcasses attracted a mean of 16.6 individual scavengers (range 0-79). Seven different species fed on a carcass at least once during 1998, with Bald Eagles (Haliaeetus leucocephalus) and Northwestern Crows (Corvus caurinus) being the most common scavengers. In 1996, Bald Eagles arrived first in 26.7% of the trials. In 1998, Northwestern Crows arrived first in 50.0% of the trials with Bald Eagles and Northern Harriers (Circus cyaneus) each arriving first in 16.7% of the trials. Results: demonstrate that individual poisoned duck carcasses can place numerous scavengers of a variety of species at risk for secondary poisoning due to high incidence of discovery and rapid exchange of information among birds.

Petrie, S. A. and K. L. Wilcox (2003). "Migration chronology of Eastern-Population Tundra Swans." Canadian Journal of Zoology-Revue Canadienne De Zoologie 81(5): 861-870.

We used satellite platform transmitting transmitters (PTTs) in 1998-2000 to track spring and fall migratory movements of Tundra Swans (Cygnus columbianus columbianus) captured at Long Point, Ontario. Migration corridors reported here corroborated those identified in previous studies using alphanumerically coded neck collars. However, PTTs provided additional information on duration of spring and fall migrations, duration of stay in different staging regions, time spent on breeding and wintering areas, and migration speed. Birds migrated between the Atlantic coast and northern prairies along a narrow geographic corridor through portions of the southern Great Lakes. From the northern prairies, swans followed 3 corridors to breeding areas on the west coast of Hudson Bay, central High Arctic, and Mackenzie River delta. While swans spent considerable time on Great Lakes (27% of spring migration) and northern prairie (40%) staging areas in spring, the northern boreal forest was an important fall staging area (48% of fall migration). Tundra Swans spent 20% of the annual cycle on wintering areas, 28% on spring staging areas, 29% on breeding areas, and 23% on fall staging areas. The long duration of migration and the fact that birds spend half their lives on staging areas underscore the importance of conserving Tundra Swan migratory habitats. Thirty-gram neck-collar-attached PTTs were more suitable than 95-g Teflon-harness-attached backpack PTTs for tracking Tundra Swans.

Shepherd, P. C. F., D. B. Lank, et al. (2001). "Sex ratios of Dunlin wintering at two latitudes on the Pacific coast." Condor 103(2): 352-360.

Latitudinal dines in sex ratio during the nonbreeding season occur in some shorebirds of the Scolopacidae. We compared populations of nonbreeding Dunlin (Calidris alpina pacifica) from two latitudes along the Pacific flyway: the Fraser River Delta, British Columbia, and Bolinas Lagoon, California, to determine whether, and to what degree, they exhibited sex ratios consistent with a latitudinal cline. Dunlin are plumage monomorphic, so we used a maximum likelihood model to estimate overall and monthly sex ratios for each population based on culmen length distributions. Sex ratios in the Fraser River Delta were corrected for sex differences in habitat use. Monthly sex ratios were similar at the two sites but varied throughout the winter, likely reflecting differences in seasonal movement patterns between the sexes. Both populations showed an overall bias toward males (Fraser = 61% males, Bolinas = 65% males). Since there is no evidence to support the possibility of a skew toward males in C. a. pacifica as a whole, our data are consistent with some form of latitudinal dine in the sex ratio of C. a. pacifica. However, additional data from the Oregon coast, southern California, and Mexico are required to resolve this question. We also tested the hypothesis that mean body size within each sex is larger at the higher-latitude site (Fraser River Delta), but this did nor appear to be the case.

Shepherd, P. C. F. and D. B. Lank (2004). "Marine and agricultural habitat preferences of dunlin wintering in British Columbia." Journal of Wildlife Management 68(1): 61-73.

We examined winter habitat preferences of individual dunlin (Calidris alpina) in the Fraser River del La, British Columbia, Canada, adjacent to agricultural land near an area of dense and increasing human settlement. We used radiotelemetry and compositional analysis to quantity and describe dunlin habitat selection at 2 scales (regional and local) throughout the 24-hr day and daily tidal cycles. We tested for differences between sex and age classes, and among birds captured at different sites. Patterns of habitat preference differed between sexes and among dunlin from different sites in the delta, but we detected no difference between age classes. We ranked habitat types in order of dunlin preference and tested for significant differences among habitat ranks. Dunlin showed a significant preference for tidally influenced marine habitats at both scales and throughout the study area. However, most individuals (>80%) also used terrestrial habitats, usually during high tide and primarily at night. The role of terrestrial habitats in the ecology of Fraser River delta dunlin previously had been underestimated because these habitats are used far more at night than during the day. Regionally, soil-based agricultural crops ranked above other terrestrial habitats, and pasture was the only terrestrial habitat that was ranked highly and preferred at both scales. Pasture vegetation tends to be short, and pasture fields in the Fraser River delta are fertilized heavily and naturally with cattle manure. We recommend that managers promote the maintenance of a mosaic of soil-based agricultural crops-with a particular emphasis on naturally fertilized pastures-for dunlin and other shorebirds wintering in the Fraser delta. Terrestrial habitat fragmentation also should be kept to a minimum, as dunlin preferred large fields, likely in response to predation risk.

So, M. K., S. Taniyasu, et al. (2004). "Perfluorinated compounds in coastal waters of Hong Kong, South China, and Korea." Environmental Science & Technology 38(15): 4056-4063.

Perfluorinated compounds (PFCs), such as perfluorooctanesulfonate (PFOS) and related compounds, have recently been identified in the environment. PFOS, the terminal degradation product of many of the PFCs, has been found globally in many wildlife species, as well as open ocean waters, even in remote regions far from sources. In this study, a solid-phase extraction procedure coupled with high-performance liquid chromatography interfaced to high-resolution mass spectrometry was used to isolate, identify, and quantify small concentrations of PFCs in seawater. These techniques were applied to investigate the local sources of PFCs in several industrialized areas of Asia and provide information on how the PFCs are circulated by coastal currents. Ranges of concentrations of PFOS in coastal seawaters of Hong Kong, the Pearl River Delta, including the South China Sea, and Korea were 0.09-3.1, 0.02-12, and 0.04-730 pg/mL, respectively, while those of perfluorooctanoic acid (PFOA) were 0.73-5.5, 0.24-16, and 0.24-320 pg/mL, respectively. Potential sources of PFCs include major industrialized areas along the Pearl River Delta of southern China and major cities of Korea, which are several of the fastest growing industrial and economic regions in the world. Detectable concentrations of PFOS and PFOA in waters of southern China were similar to those in the coastal marine environment of Japan and certain regions in Korea. Concentrations of PFCs in several locations in Korean waters were 10-100-fold greater than those in the other locations on which we report here. The spatial and seasonal variations in PFC concentrations in surface seawaters in the Pearl River Delta and South China Sea indicate the strong influence of the Pearl River discharge on the magnitude and extent of PFC contamination in southern China. All of the concentrations of PFOS were less than those that would be expected to cause adverse effects to aquatic organisms or their predators except for one location in Korea adjacent to an industrialized area. Hazard quotients were from <0.001 to 0.002 for aquatic animals and ranged from <0.001 to 17 for predatory birds.

Talbot, S. L., J. M. Pearce, et al. (2003). "Molecular status of the dusky Canada goose (Branta canadensis occidentalis): A genetic assessment of a translocation effort." Conservation Genetics 4(3): 367-381.

Until recently, the dusky Canada goose (Branta canadensis occidentalis) was managed as one breeding population from the Copper River Delta (CRD), Alaska. Population numbers on the CRD have declined precipitously over the last three decades, due in part to changes in habitat. In 1981, a pair of Canada geese, presumably B. c. occidentalis, was reported nesting on Middleton Island (MID), in the Gulf of Alaska. Numbers of Canada geese on the island increased in the decade subsequent to a translocation of geese from CRD to MID, but it is unclear whether the increase is attributable to the translocation effort. We used genetic data derived from three classes of genetic markers to clarify relationships of Canada geese breeding in south-coastal Alaska. Geese were sampled from 5 populations: CRD, MID, Anchorage (ANC), Admiralty Island (ADM) in southeastern Alaska, and Green Island (GRN) in Prince William Sound (PWS). Mitochondrial DNA analyses demonstrate Canada geese from MID are nearly monomorphic for a unique haplotype fixed on GRN but not found in CRD or any other breeding population. Furthermore, nuclear markers consistently cluster MID with GRN to the exclusion of CRD. We suggest the current population on MID is not derived from birds translocated from CRD, but rather that MID was most likely colonised by birds inhabiting other island habitats within the PWS. Furthermore, since geese from the CRD share mtDNA haplotypes with geese from other breeding locales, they apparently share recent common ancestry and/or gene flow with populations representing other subspecies. Our genetic data raise questions about the validity of current management units of Canada geese.

Volponi, S. (1996). "Bill deformity in a Pygmy Cormorant (Phalacrocorax pygmeus) chick." Colonial Waterbirds 19(1): 147-148.

The occurrence of a congenital malformation in the Pygmy Cormorant (Phalacrocorax pygmeus) is reported. In 1995, a cross-billed chick was observed in the natural reserve of Punte Alberete (southern Po Delta, northern Italy) where a small colony of Pygmy Cormorant became established in 1994.

Warnock, N. and M. A. Bishop (1998). "Spring stopover ecology of migrant Western Sandpipers." Condor 100(3): 456-467.

We describe stopover ecology for 132 migrant radiomarked Western Sandpipers (Calidris mauri) relocated repeatedly along the Pacific Flyway of North America. Eighty-eight percent of radiomarked birds were detected at 1-5 sites north of their banding sites, at distances ranging from 240-4,000 km away. We compare length of stay and physical indices of Western Sandpipers banded at coastal sites (San Francisco Bay, California and Grays Harbor, Washington), and an interior, western Great Basin site (Honey Lake, California). Western Sandpipers radiomarked at the interior site had significantly shorter length of stays than birds radiomarked at coastal sites, and they had significantly lower fat scores. The ephemeral nature of Great Basin stopover sites and an increased risk of predation may explain some of this variation. Fat and body condition indexes explained little of the observed variation in length of stay of Western Sandpipers at banding and other stopover sites. Length of stay of birds radiomarked at Grays Harbor were significantly longer compared to birds radiomarked to the south that also stopped at Grays Harbor, suggesting a potential capture effect on length of stay of birds at banding sites. Mean length of stays at seven sites other than banding sites ranged from 1.1-3.3 days and were not significantly affected by sex of bird, year of study, or banding location. Length of stay of male Western Sandpipers at the Copper River Delta, Alaska became significantly shorter later in the migration period, but not for females. Coastal sites along the Pacific Flyway from San Francisco to the breeding grounds generally function as stopovers for Western Sandpipers instead of staging areas.