Fall Staging Research Articles

Mallards Feeding on Salmon Carcasses in Alaska

Mallards (Anas platyrhynchos) are known to frequent rivers and streams during post-breeding. I describe observations of Mallards feeding on fresh Pacific salmon (Onchorhynchus spp.) carcasses in Alaska on two separate occasions during July– August 2005. These observations represent the first reported use of salmon carcasses by Mallards in Alaska. This strategy may be fairly common for a segment of post-breeding and fall staging Pacific Flyway Mallards in Alaska, particularly those that inhabit streams and rivers used by the five species of Pacific salmon during the spawning season.

Why do Eared Grebes Leave Hypersaline Lakes in Autumn?

Jehl (1988) observed that the departure of Eared Grebes Podiceps nigricollis from Mono Lake, California, a major fall staging area, did not occur in relation to time of year or weather but was initiated after the density of brine shrimp (Artemia monica)-the major prey-fell below a predictable threshold. Although Caudell and Conover (2006) found no such relationship at Great Salt Lake, the other major staging area, reevaluation of their data indicates that the threshold concept applies there as well. Substantial differences in the staging ecology of Eared Grebes at the two lakes remain to be demonstrated.

Staging, Migration, and Winter Distribution of Canada and Cackling Geese Staging in Interior Alaska

The breeding stock composition and ecology of Canada (Branta canadensis) and cackling (B. hutchinsii) geese, collectively white-cheeked geese, staging in interior Alaska and wintering in the Pacific Northwest is poorly understood. We captured, measured, and applied neck collars to white-cheeked geese during spring and fall staging near Fairbanks and Delta Junction, Alaska, USA, to study their breeding stock composition, migration, and winter distribution. We measured exposed culmen, flattened wing chord, total tarsus, and body length of geese staging in interior Alaska to assist with determination of breeding stock. The first principal components, as well as a univariate measurement of exposed culmen, indicated geese trapped in Fairbanks in the fall were larger on average than geese trapped in Delta Junction in either spring or fall. We observed or recovered most of the banded geese detected in fall and winter in central British Columbia, Canada, central Washington, USA, and north-central Oregon, USA, east of the Cascade Mountains, with relatively few observations in western British Columbia, Washington, and Oregon. We found no evidence of movement between wintering areas on the east and west sides of the Cascade Mountains. Geese that we trapped during spring staging in Delta Junction were more often observed on the west side of the Cascade Mountains than geese trapped during fall staging in Fairbanks. Most (93%) geese trapped during fall staging in both Fairbanks and Delta Junction, however, wintered east of the Cascade Mountains. After-hatch-year (AHY) geese from interior Alaska staging areas observed on the west side of the Cascade Mountains were structurally smaller on average than AHY geese observed on the east side of the Cascade Mountains. Our results indicate fall staging white-cheeked geese in Fairbanks were predominantly 1 breeding stock of white-cheeked geese, while fall and spring staging white-cheeked geese in Delta Junction comprised at least 2 stocks of white-cheeked geese. Based on our findings, we recommend separate harvest and management strategies be considered for small white-cheeked geese migrating through coastal and central British Columbia and wintering east and west of the Cascade Mountains in Washington and Oregon to avoid potential overharvest of independent breeding stocks.

Spatial, Temporal and Weather factors Influencing the Foraging Behavior of Migrating Semipalmated Sandpipers

The role of spatial, temporal and weather factors on the foraging behavior of migrating Semipalmated Sandpipers (Calidris pusilla L.) was explored during fall staging in the upper Bay of Fundy (Canada) over two years. Factors that influence foraging benefits during migration stopover may influence fitness in a migratory species. The number of captures and success rate peaked during the middle of day regardless of temperature. Pecking rate decreased with increasing temperature while the number of captures and success rate increased suggesting that foraging benefits are lower at low temperatures. The number of captures and success rate did not change as a function of tide stage or time of year despite presumed changes in prey availability and/or density. Running and flying activities were also influenced by time of day and weather factors. Difficulties in locating prey or detecting predators may explain the effect of time of day and increased thermoregulation costs and changes in prey activity are probably involved in explaining how weather factors influence foraging behavior in this species

BEHAVIORAL AND PHYSIOLOGICAL RESPONSES OF EARED GREBES (PODICEPS NIGRICOLLIS) TO VARIATIONS IN BRINE SHRIMP (ARTEMIA FRANCISCANA) DENSITIES

Abstract Eared Grebes (Podiceps nigricollis) use the Great Salt Lake (GSL) primarily as a fall staging area. They feed on brine shrimp (Artemia franciscana) to build up energy reserves to complete their southward migration. Whereas it has been speculated that timing of grebe departure from the GSL is due to declining shrimp density, this hypothesis has not been tested. We monitored grebe weight, behavior, and departure dates to test this hypothesis and to determine the effects of declining shrimp densities on Eared Grebes during 1999, 2000, and 2001 when there were different shrimp densities. Despite differences in shrimp densities, grebes left the GSL about the same time each year. Juvenile and subadult mass was significantly lighter (P 0.05) in dive or surface duration between 1999 and 2000, there were differences in the perc...

SPATIOTEMPORAL HETEROGENEITY OF GREATER SNOW GOOSE HARVEST AND IMPLICATIONS FOR HUNTING REGULATIONS

Changes in harvest rate over the past 3 decades have been shown to be closely related to population growth of greater snow geese (GSG; Chen caerulescens atlantica). We used band-recovery and harvest survey data from 1970 to 2001 to study temporal variations in geographic harvest distribution and composition of GSG in Québec, Canada and the Atlantic Flyway states (AF) in the United States. We sought to determine whether (1) geographic variation in harvest was associated with temporal trends in total harvest rates observed during this period; (2) spatiotemporal distributions of harvest varied with age and sex; and (3) harvest distribution and composition differed between the spring conservation harvest initiated in 1999 and the regular fall hunt in Québec. We detected over time a gradual spreading in the geographic distribution of the fall harvest from the upper St. Lawrence estuary toward southwestern Québec. During winter, a sudden northward shift in the distribution of the United States harvest in the mid-1980s was associated with a high concentration of geese in mid-Atlantic Flyway states (Maryland, Delaware, and New Jersey), possibly due to short-stopping during migration. We argue that this led to a reduction of hunting pressure on GSG and may have contributed to the sudden decline in harvest rate that occurred at that time and ultimately to the ensuing population increase. We observed a decreasing proportion of juveniles in the kill throughout the hunting season within fall staging grounds in Québec and between Québec and the United States. We also found a much higher proportion of adults in the spring harvest than in the fall that is consistent with the conservation goal of increasing the adult harvest. We recommend that management actions focus on increasing harvest in mid-Atlantic Flyway states if further control of population growth is desired.

TEMPORAL AND GEOGRAPHIC VARIATION IN SURVIVAL OF JUVENILE BLACK BRANT

Abstract First-year survival has important implications for the structure and growth of populations. We examined variation in seasonal survival of first-year Pacific Black Brant (Branta bernicla nigricans) marked late in summer in Alaska at two brood-rearing areas on the Yukon-Kuskokwim Delta (Tutakoke and Kokechik) and one area on the Arctic Coastal Plain to provide insight into the magnitude and timing of mortality during fall migration. First-year survival was lower in early fall (15 July–1 October), when birds fledged from brood-rearing areas and migrated to their primary fall staging area at Izembek Lagoon, Alaska, than during late fall and early winter (1 October–15 February), when birds made a long-distance transoceanic flight (>5000 km) to wintering areas in Baja California, Mexico. When compared to other years, monthly survival during early fall was 20–24% lower in 1992, the year of latest hatch dates and slowest growth of goslings. There was strong evidence to indicate that survival varied geogr...

Moult intensity and chronology of Tundra Swans during spring and fall migration at Long Point, Lake Erie, Ontario

Moult intensity and chronology in staging Eastern-Population (EP) Tundra Swans (Cygnus columbianus columbianus) were studied during spring in 1999 and 2000 (n = 35) and during fall in 1999, 2000, and 2001 (n = 47) at Long Point, Lake Erie, Ontario. To test for age, sex, and seasonal differences in moult intensity, 20 feather regions were scored according to the proportion of growing feathers. Adult, subadult, and juvenile Tundra Swans moulted contour feathers at low intensities during spring and fall. Males and females of all three age classes had similar patterns and intensities of moult during spring and fall. Shared costs of incubation and brood rearing, perennial monogamy, and lack of a breeding plumage could be some of the pressures selecting for intersexual similarities in feather replacement during migration. Adult, subadult, and juvenile Tundra Swans moulted more intensively during fall than spring. Larger lipid reserves and seasonal dietary differences may allow fall-staging Tundra Swans to moult more intensively than spring-staging birds at Long Point. Overlap of nutritionally costly events (moult and migration) may be necessary as Tundra Swans spend half of their annual cycle on spring and fall staging areas. However, reduced daily nutritional costs associated with moulting at low intensities and migrating slowly apparently permits the overlap of these two life-cycle events.

Migration chronology of Eastern-Population Tundra Swans

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.

Effects of Gull Predation and Weather on Survival of Emperor Goose Goslings

Numbers of emperor geese (Chen canagica) have remained depressed since the mid-1980s. Despite increases in glaucous gulls (LOTUS hyperboreus), a primary predator of goslings little information existed to assess whether recent patterns of gosling survival have been a major factor affecting population dynamics. We used observations of known families of emperor geese to estimate rates of gosling survival during 1993-96 on the Yukon-Kuskokwim Delta, Alaska. Survival of goslings to 30 days of age varied among years from 0.332 during 1994 to 0.708 during 1995. Survival was lowest during 1993-94, which corresponded with the years of highest frequency of disturbance of goose broods by glaucous gulls. Rainfall during early brood rearing was much higher in 1994 than other years, and this corresponded to low survival among goslings ≤5 days of age. Numbers of juveniles in families during fall staging were negatively related to rainfall during early brood rearing (n = 23 yr). Although there are no data to assess whether gosling survival in emperor geese has declined from some previous level current survival rates of emperor goose goslings are as high as or higher than those observed in other goose species that are rapidly increasing. A proposed reduction of glaucous gull numbers by managers may not be the most effective means for increasing population growth in emperor geese.

Population Studies of Wilson's Phalaropes at Fall Staging Areas, 1980-1997: A Challenge for Monitoring

-The great majority of adult Wilson's Phalaropes (Phalaropus tricolor) is thought to stage at Great Salt Lake, Utah, Mono Lake, California, and/or Lake Abert, Oregon, before making a nonstop flight to South America. Their concentration at a few localities provides an exceptional opportunity for studying trends species-wide, so long as several important assumptions are fulfilled. Observations from 1980 through 1997 indicated that numbers of staging adults approximated 500,000-600,000 in thel980s, then dropped by about half in the 1990s. Data from the breeding grounds in 1967-1992, including Breeding Bird Surveys, also indicated a general decline had been in progress, but did not indicate any sudden recent changes. The validity and severity of the decline is hard to test because correspondence between population sizes predicted from BBS trends and observations from staging areas is poor. Difficulties in gathering and interpreting data from a species that is easy to study raises questions about our ability to monitor and understand population trends in less amenable species. Whether population fluctuations in Wilson's Phalaropes are related to the availability of habitat in the main breeding range requires confirmation. Received 8January 1999, accepted 13January 1999.

Himasthla limnodromi n. sp. (Digenea: Echinostomatidae) from the Short-Billed Dowitcher, Limnodromus griseus (Aves: Scolopacidae)

Himasthla limnodromi n. sp. is described from short-billed dowitchers, Limnodromus griseus, from the Araya Peninsula, Venezuela, and Delaware Bay, U.S.A. Himasthla limnodromi was not found in dowitchers on the breeding grounds or on the fall staging grounds in the Bay of Fundy but reappeared in dowitchers on the wintering grounds in the fall. This suggests that H. limnodromi is acquired by the birds on arrival on the wintering grounds and then gradually disappears during the birds' northward migration in the spring. The new species has a reniform collar armed with 31 spines, with 23 in a single uninterrupted row, and 4 corner spines in overlapping pairs at each end. The cirrus sac is up to 10 times longer than the length of the acetabulum and contains a long, smooth cirrus. The vitellaria always commence posterior to the posterior end of the cirrus sac in mature specimens. The testes are found in the posterior eighth of the long, filamentous body. Himasthla limnodromi n. sp. most closely resembles Himasthla alincia, but H. limnodromi is larger in size and has an unspined cirrus and smaller eggs.

Decline in Body Mass, Size, and Condition of Greater Snow Geese, 1975-94

In some colonies of arctic-nesting geese, declines have been observed in body mass, size, and condition (body mass relative to size) of goslings at fledging, with a resulting decrease in juvenile survival during fall migration. These declines have been attributed to overgrazing by increasing goose populations on brood-rearing areas. We examined 25,761 greater snow geese (Anser caerulescens atlanticus) shot by hunters at the main fall staging area on the St. Lawrence River, Quebec, from 1975 to 1994, to determine whether there were long-term trends in body mass, size, and condition in this increasing population. Mean annual body mass and culmen length (an indicator of body size) of adult males, adult females, juvenile males and juvenile females showed annual fluctuations and declines over time. Body mass declined by 9.6% (a loss of 312 g, SE = 61 g) over 19 years (1975-94) in adult males, 11.2% (333 g, SE = 51 g) in adult females, 9.2% (245 g, SE = 30 g) in juvenile males, and 8.7% (211 g, SE = 34 g) in juvenile females. Culmen length declined by 2.2% (1.5 mm, SE = 0.4 mm) over 18 years (1976-94) in adult males, 0.9% (0.6 mm, SE = 0.3 mm) in adult females, 1.5% (1.0 mm, SE = 0.5 mm) in juvenile males, and 1.5% (0.9 mm, SE = 0.3 mm) in juvenile females. Body mass adjusted to a standard culmen length showed a decline in body condition. Predicted body condition declined by an average of 6.5% (loss of 209 g, SE = 79 g) over 18 years (1976-94) in adult males, 8.5% (248 g, SE = 56 g) in adult females, 6.0% (158 g, SE = 50 g) in juvenile males, and 5.9% (142 g, SE = 41 g) in juvenile females. We suggest that changing conditions on arctic brood-rearing areas are responsible for these declines. Increasing numbers of goslings may be encountering a reduced per capita availability of food and therefore experiencing lower growth rates and reduced final size. The long-term decline in the size and condition of these geese has not yet led to measurable reductions in reproductive output. With continued population growth, we predict further deterioration of body condition of the geese and an eventual increase in the mortality of juveniles during fall migration.

Use of ice-scoured depressions by marsh-foraging snow geese (Chen caerulescens atlantica)

We describe the foraging behaviour of staging greater snow geese (Chen caerulescens atlantica) as they feed in depressions caused by ice scouring in tidal marshes along the St. Lawrence River. We compared feeding success during the fall and spring staging season as the birds extracted rhizomes of Scirpus americanus. In these marshes, every growth cycle (summer) is followed by two distinct episodes of intensive exploitation by geese (fall and the following spring). Two kinds of foraging bouts were considered: (1) successful (i.e, with one or more ingestions) and (2) unsuccessful (i.e, without any ingestion). Geese sampled fewer depressions in the fall than in the spring because the proportion of depressions sampled with success was greatest in this season. Geese spent less time per depression in the spring, whether they were successful or not, but sampled more depressions instead. There was a decrease in the number of depressions sampled over the spring period. It is concluded that geese adjust their use of ice-scoured depressions to both inter- and intra-seasonal food availability (depletion). Behavioural mechanisms they might use to do so are discussed.

Evidence of Emperor Geese Breeding in Russia and Staging in Alaska

Evidence of Emperor Geese Breeding in Russia and Staging in Alaska

Effects of Harness-Attached Transmitters on Premigration and Reproduction of Brant

Radio transmitters are an important tool in waterfowl ecology studies, but little is known about their effects on free-ranging geese. We attached transmitters to female brant (Branta bernicla nigricans) to investigate migration schedules at a fall staging area, return rates to nesting grounds, and nesting rates of returning females in subsequent breeding seasons. Radio-tagged females (n = 62) carried either 35-g back-mounted transmitters attached with ribbon harnesses, or 26 or 32-g back-mounted transmitters affixed with plastic-coated wire harnesses (Dwyer 1972). Arrival and departure schedules at Izembek Lagoon, Alaska, did not differ (P > 0.05) between radio-tagged females and the entire population in 1987-89. Color-banded females with transmitters returned to the breeding colony in subsequent nesting seasons (1988-92) at a lower (P ≤ 0.003) rate (≤4%) than color-banded females without transmitters (57-83%). The 1 returning color-banded female with a transmitter did not breed, while an average 90% of the returning color-banded females without transmitters nested in subsequent breeding seasons (P = 0.005). Back-mounted, harness-attached transmitters may bias data in studies of waterfowl behavior, productivity, and survival

Effects of Summer Feeding Area on Gosling Growth in Snow Geese

Relative growth of body parts (wing, culmen, tarsus) in young Snow Geese differed among years and among summer feeding areas only a few kilometers apart in the vicinity of the McConnell River, Northwest Territories, Canada. Gosling age was unknown at time of capture, so we expressed all differences in measured characteristics as a function of culmen length. This procedure may underestimate the magnitude of differences in growth with respect to age. Year and summer feeding area had large, independent effects on relative growth. Growth of primary feathers showed the greatest variation of measurable variables among feeding areas. We argue that the cause of most differences in relative growth was nutritional variation of vegetation. If goslings with retarded growth do not entirely catch up on fall staging areas, there may be lasting demographic effects.

Distribution and movements of Greater Snow Geese, Chen caerulescens atlantica, during fall staging in the St. Lawrence estuary, Quebec

Distribution and movements of Greater Snow Geese, Chen caerulescens atlantica, during fall staging in the St. Lawrence estuary, Quebec

Migration Patterns of the Mississippi Valley Population of Canada Geese

Aerial surveys to locate radio-marked Canada geese (Branta canadensis interior) of the Mississippi Valley Population (MVP) indicated all and spring migration 1984-86 was concentrated in a corridor in central Illinois and southeastern Wisconsin. A major spring staging area was identified in the Kaskaskia River Valley of central Illinois. Chronology of departure from wintering areas varied annually, but timing of departure from Wisconsin staging areas and arrival on nesting areas in Ontario was similar among years. Chronology of fall migration varied annually, and timing of movements of birds from Wisconsin to southern Illinois caused underestimates in midwinter population inventories (conducted mid-Dec) in 3 of 4 years. Homing rates of segments of the MVP associated with fall staging in Wisconsin versus southern Illinois did not differ (P>0.20) from rates that could be expected based on numbers of geese using Wisconsin versus Illinois in fall. We found no evidence to support the existence of manageable subpopulations of the MVP

Conditioning of Sandhill Cranes during Fall Migration

Body mass of adult female and male sandhill cranes (Grus canadensis) increased an average of 17 and 20%, respectively, from early September to late October on staging areas in central North Dakota and varied by year. Increases in body mass averaged 550 and 681 g among female and male G. c. canadensis, respectively, and 616 and 836 g among female and male G. c. rowani. Adult and juvenile G. c. rowani were lean at arrival, averaging 177 and 83 g of fat, respectively, and fat reserves increased to 677 and 482 g by mid-October. Fat-free dry mass increased by 12% among juveniles, reflecting substantial growth, but remained constant among adults. The importance of fall staging areas as conditioning sites for sandhill cranes, annual variation in body mass, and vulnerability of cranes to habitat loss underscore the need to monitor status of fall staging habitat in the northern plains region and to take steps to maintain suitable habitat where necessary. J. WILDL. MANAGE. 54(2):234-238 During fall migration, midcontinent populations of 3 subspecies of sandhill crane (G. c. canadensis, G. c. rowani, and G. c. tabida) stop for extended periods on traditional staging areas in the northern plains region of North America before continuing southward to wintering grounds located primarily in Texas and New Mexico (Johnson and Stewart 1973, Lewis 1977, Tacha et al. 1984). Cranes that nest in central and arctic Canada, Alaska, and eastern Siberia spend most of September and October on staging areas in eastern Alberta, Saskatchewan, Manitoba, North Dakota, South Dakota, and northwestern Minnesota (Lewis 1977, Melvin and Temple 1983). In North Dakota, subspecies composition varies by site. Cranes staging in the westcentral region (McLean County) are primarily G. c. canadensis, whereas cranes in the This content downloaded from 207.46.13.189 on Thu, 04 Aug 2016 05:14:12 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 54(2):1990 CRANE BODY COMPOSITION * Krapu and Johnson 235 central part (Pierce and Kidder counties) are primarily G. c. rowani (Johnson and Stewart 1973). The fall distribution of the midcontinent population of G. c. tabida is centered in northwestern Minnesota, and their distribution in North Dakota is limited primarily to a small population in Kidder County (Johnson and Stewart 1973). The subpopulations of sandhill cranes that stage in Kidder and McLean counties spend winter primarily along the Texas Gulf Coast (50,000-70,000 cranes, Tacha et al. 1984) and western Texas (450,000 cranes, Iverson et al. 1985), respectively. The significance of fall staging areas in the northern plains region as conditioning sites for the midcontinent sandhill crane population is poorly understood. The prolonged stay on these staging areas probably prepares birds physiologically for the continuation of fall migration (Melvin and Temple 1983) and possibly for winter, much as spring staging areas along the Platte and North Platte rivers physiologically prepare cranes for spring migration and reproduction (Krapu et al. 1985). However, fat levels among migrant sandhill cranes collected in Oklahoma in October 1979 were much lower than observed late in the spring staging period of the same year in Nebraska (Iverson 1981). This difference suggests, at least during some years, that cranes acquire less fat during autumn staging intervals in the Great Plains region than during spring, possibly because of less suitable foraging conditions on fall staging areas. We address (1) patterns of body mass change among adult G. c. canadensis and G. c. rowani on staging areas in North Dakota during the fall stopover and (2) the magnitude of change in body nutrient composition of G. c. rowani from early to late in the fall staging period. The North Dakota Game and Fish Department and cooperators provided measurements on hunter-shot cranes; B. A. Hanson and R. O. Woodward assisted in collecting and processing cranes, and C. R. Luna prepared the figures. D. P. Fellows gave constructive comments on an earlier draft of the manuscript.