Using constant-effort catch data, causes of annual variation in the timing of migration of Curlew Sandpipers (Calidris ferruginea) migrating through Ottenby, Sweden, as well as the trend in timing of migration from 1946–2005, was investigated. Variation in the timing of autumn migration of adult and juvenile Curlew Sandpipers was influenced by breeding success connected to predation pressure on the Arctic breeding grounds. Median migration date of adult birds was significantly later in good breeding years compared with poor breeding years while the migration of juveniles was earlier in good breeding years compared with poor breeding years. Also, adults migrated earlier when the average temperature in June was warmer. Median migration dates of adults have advanced by 23 days from 1946–2005, but the migration dates of juveniles have remained unchanged. Unchanged migration dates of juveniles indicate that earlier departure of the adult Curlew Sandpipers from the breeding grounds was not due to earlier breeding. Evidence suggests that declining breeding productivity as a result of increasing predation on broods of shorebirds might, over the years, be the reason for the observed pattern of early departure of adults from the breeding grounds. One possible consequence of earlier migration is a mismatch between timing of migration and periods of food abundance on migration routes and at the wintering grounds, leading to a decline in adult and juvenile survival and population size.

Spring-migration ecology of staging Northern Pintails, Anas acuta, was investigated in south-central Nebraska, USA. Habitat associations, local movements, settling patterns, arrival dates, residency times and survival were estimated from 71 radiomarked pintails during spring 2001, 2003 and 2004, and diet determined from 130 females collected during spring 1998 and 1999. Seventy-two percent of pintail diurnal locations were in palustrine wetlands, 7% in riverine wetlands, 3% in lacustrine wetlands, 6% in municipal sewage lagoons and irrigation reuse pits and 10.5% in croplands. Emergent wetlands with hemi-marsh conditions were used diurnally more often than wetlands with either open or closed vegetation structures. Evening foraging flights averaged 4.3 km (SE = 0.6) and 72% were to cornfields. In accord with these findings, 87% of 93 pintails collected during spring 1998 and 1999 returning to evening roosts consumed corn, which represented 84% dry mass of all foods. Pintails collected on non-cropped wetlands ingested invertebrates and seeds from wetland plants more frequently than birds returning to roost. Radiomarked pintails arrived in Nebraska on 7 March 2003 and 18 February 2004; average arrival date was six days earlier during 2004 compared to 2003. Residency time for individuals varied greatly (1–40 days) yet yearly means were similar and averaged 9.5 days within the region. No mortality was detected for 71 birds monitored over 829 exposure days. Conservation planners linking population dynamics and habitat conditions at spring-staging areas need to focus on pintail body condition during spring and its connection with reproductive success and survival during the breeding season.

Population structure of Harlequin Ducks (Histrionicus histrionicus) wintering in the Strait of Georgia, British Columbia, was evaluated by generating age, sex, paired status and distance-specific movement rates with multi-stratum mark-recapture analyses, and age and sex-specific movement distances through surveys of marked individuals. Annual movement distances and rates did not differ by sex, but only 2–4% of adults (third year and afterthird year) compared to 7–11% of subadults (hatch year and second year) moved among locations per year and distance moved decreased with age. Adults were highly site faithful regardless of sex and paired status. The stepping stone gene flow model estimated the among population component of genetic variance (F_ST) at 0.005, suggesting that winter movement by subadults was sufficient to explain results of previous genetic analyses that detected no fine scale genetic structuring. Seasonal movement rates indicated that at least 95% of individuals molt and winter in the same location, and that annual aggregation at Pacific Herring (Clupea pallasi) spawning sites facilitates demographic mixing and gene flow. Low annual movement rates (0.001) between the northern and southern Strait of Georgia and dispersal by both sexes suggest that a metapopulation distribution may function within the Pacific Coast range, which is relevant to the geographic scale of management. Movement rates and distances suggest that subadult survival rates are particularly vulnerable to underestimation.

Ten geolocators (light-level data loggers) were attached to Common Terns (Sterna hirundo) at a breeding site in the northeastern USA in 2007 and 2008; six were retrieved (five with useful data) in 2008 and 2009. The birds wintered in four discrete areas on the north and east coasts of South America, from Guyana (6–7°N) to northeastern Argentina (36–42°S); three remained within restricted areas for most or all of the winter, whereas two ranged more widely. They left the breeding area at various dates between 1 August and 14 September; three migrated directly from the breeding area while two first moved southwest to stage near Cape Hatteras. All five birds flew directly to the vicinity of Puerto Rico, then moved along the north and east coasts of South America, staging at scattered locations for periods of 3–11 d, before reaching their winter quarters at various dates from 6 September to 26 October. Two birds left their winter quarters on 2 March and 4 April, staged in northern Brazil for 47 and 6 d, then traveled via the Bahamas to reach the breeding site on 1 May. During breeding and post-breeding periods, the birds spent a mean of 7 min each day and virtually no time at night resting on the water, but during the rest of the year they often rested on the water for up to 6 h by day and up to 11 h at night. Leg-mounted geolocators caused several adverse effects but did not reduce survival.

Two invertebrates, brine shrimp (Artemia franciscana) and brine flies (Ephydridac), occur in great densities in the Great Salt Lake (GSL) but it is unknown whether ducks forage extensively on them during winter or rely on freshwater food. Common Goldeneye (Bucephala clangula), Northern Shoveler (Anas clypeala) and Green-winged Teal (Anas crecca) were collected from the GSL during winters 2004–05 and 2005–06 to evaluate their food habits. Brine shrimp and brine flies comprised more than 70% of the winter diet of these ducks. Common Goldeneyes consumed mainly brine fly larvae (68% based on dry weight biomass), which live primarily along the substrate. Northern Shovelers fed on brine shrimp cysts (52%) and adult brine shrimp (20%) while Green-winged Teal consumed mainly brine shrimp cysts (80%). In some years, up to half of the brine shrimp cysts in the GSL are commercially harvested. Care should be taken so that this commercial harvest does not adversely impact ducks that depend on these brine shrimp cysts for winter food.

The incidence of lead shot ingestion in waterfowl has declined in the lower Great Lakes (LGL) following the 1999 Canada-wide ban on use of toxic shot for waterfowl hunting, but few data exist on ingestion frequencies of spent shot or fishing weights for sea ducks wintering at the LGL. Artifact ingestion was evaluated in 269 Buffleheads (Bucephala albeola), 224 Common Goldeneyes (B. clangula) and 256 Long-tailed Ducks (Clangula hyemalis) collected at Lake Ontario during winter 2002–03 and 2003–04. Long-tailed Ducks ingested total shot (lead and steel shot combined) more frequently (6.6%) than did Common Goldeneye (1.8%) and Bufflehead (0.4%). Lead shot was ingested by Long-tailed Ducks (5.1%) and Buffleheads (0.4%), but not by Common Goldeneyes. One Long-tailed Duck, 0.1 % of all specimens, ingested one lead fishing weight. Substrate type influenced artifact ingestion frequency and diving ducks that specialize on prey associated with hard substrates may continue to ingest artifacts more than ducks using soft substrate marshes. The results suggest lead toxicosis from spent shotgun pellets is presently non-existent to low in sea ducks wintering at northeastern Lake Ontario and that further restrictions on use of lead fishing tackle may have little implication for sea ducks in this region.

A free-ranging Mallard (Anas platyrhynchos) population was investigated during winter (December–January 1996–1999) below the Garrison Dam, North Dakota, USA, to relate diet to gut morphology variation in males. Four explanatory variables (fish consumption, male age, winter, and body size) were evaluated as to whether they influenced five response variables associated with gut characteristics of Mallards. Response variables were lower gastro-intestinal tract mass (LGIT), dry liver mass, dry gizzard mass, small intestine length, and ceca length. Diets of Mallards were comprised primarily of Rainbow Smelt (Osmerus mordax) and concomitantly variation in gizzard mass was small. LGIT mass of juveniles was larger than that of adults, greater for those that consumed fish, and greater during the coldest and snowiest winter. Liver mass and small intestine length of Mallards that consumed fish were greater than those that did not. Mallards may maintain lengthy intestines to increase digestive efficiency. Gut size variation was not entirely attributable to dietary composition but also influenced by body size and environmental conditions such that over-winter survival is maximized.

Access to human-derived food is thought the major cause of population increases in many gull species, and the degree to which urbanized gulls depend upon anthropogenic food may be resolved by isotopic benchmarks. Stable isotope ratios (δ¹³C and δ¹⁵N) were compared between Silver Gulls breeding at a remote, nonurbanized site (Furneaux Island Group, Bass Strait) and those at an urban (Hobart) colony in Tasmania to distinguish potential differences in feeding regime. Analyses of whole blood stable isotopes revealed that non-urbanized gulls tended to have a mixed diet from several sources, while urban gulls fed on a separate food web from and a more freshwater origin. No differences in the stable isotope ratios were detected between sexes or among breeding periods. Birds from Hobart tended to feed at a higher trophic position after egg-laying than before, and reflected a change in food preference. These results provided critical baseline data to measure the degree of urbanization of Silver Gulls in Tasmania in order to study potential health impacts of anthropogenic food on birds.

The Crab Plover (Dromas ardeola) is a little-known shorebird that breeds colonially in self-dug burrows on islands in the north-western Indian Ocean. To test whether the “nest site limitation” hypothesis could satisfactorily explain the high nest density in this species, 21 colonies were studied in Eritrea from 2002 to 2009. The hypothesis was falsified by the following observations: across the study period, nesting colonies were relocated on the same sandbanks every year and most occupied no more than 4% of the area suitable for excavating burrows; colony size and area suitable for burrowing were not correlated; nest density and colony size were not significantly correlated; the area occupied by nests increased steadily throughout the nest-building period; nests were closely-spaced throughout the building phase rather than being scattered throughout the area eventually used for digging. These results indicate that the Crab Plover is not site-limited but a truly colonial species.

The breeding success of Common Murres (Uria aalge) and Pelagic Cormorants (Phalocrocorax pelagicus) at Triangle Island, off British Columbia, Canada, was high from 2003 to 2006; four years in which a pair of Peregrine Falcons (Falco peregrinus) nested in the vicinity. However, in three years when the falcon eyrie was inactive (2007 to 2009), adult murres were depredated on the colony by Bald Eagles (Haliaeetus leucocephalus) and murre eggs were taken by Glaucous-winged Gulls (Larus glaucescens) after eagles flushed incubating murres. Consequently, breeding success in both species was low in 2007, then in 2008 and 2009 no murres bred successfully and no cormorants built nests. That a single pair of falcons protected thousands of seabirds is noteworthy for its local conservation implications. Bottom-up control of seabird breeding success has been well documented, but there appears need for a better understanding of the role of top-down mechanisms as a result of both the direct (consumptive) and indirect (non-consumptive) effects of top predators.

Double-crested Cormorants (Phalacrocorax auritus) were not observed breeding in the inner coast of Washington and British Columbia until the 1920s and 1930s, whether the breeding was either a re-colonizing event or a new expansion was unknown. Archaeological evidence from Watmough Bay, a shell midden site on Lopez Island, San Juan Islands (Washington State), was analyzed to place the recent changes in breeding distribution in deeper historical context. The Watmough Bay faunal assemblage contains large numbers (n = 2,397) of cormorant bones. Of those specimens that could be identified to species (n = 358), 99.7% were identified as Double-crested Cormorants. The majority (97%, n = 2,336) of the cormorant remains are from juveniles or chicks, which were collected while still at the colony. Radiocarbon dating indicates the majority of the site accumulated between AD 300– 600. Evidence for a ca. 1,500-year-old Double-crested Cormorant colony near Lopez Island confirms that the species did breed in the region prior to the early 20th century. The study further documents the value of archaeological data for current wildlife management.

The Nebraska Sandhills are an important area for breeding ducks in the Great Plains, but reliable estimates of breeding populations are unavailable. Double-observer methodology was used to estimate abundance of breeding duck populations in the Nebraska Sandhills. Aerial transect surveys were conducted using methodology similar to the cooperative Waterfowl Breeding Population and Habitat Survey conducted by the U.S. Fish and Wildlife Service and Canadian Wildlife Service. Observations by two front-seat observers and one rear-seat observer were used to account for incomplete detectability. Transect-specific population size and detection probabilities were estimated using program SURVIV; estimates were species-specific by type of social grouping. Regional population sizes were obtained by extrapolating transects' estimates to the Sandhills. Detection probabilities were high (>0.75) for all species, but highest for Northern Shoveler (Anas clypeata) and Gadwall (A. strepera). Detection probabilities generally followed increases or decreases with duck densities. Uncorrected population estimates, on average, were <7% the population estimates obtained by correcting for detectability. Double-observer methodology should be considered for adjusting duck counts that cannot be corrected using additional aerial or ground surveys, particularly where water and ducks are well dispersed.

Birds at-sea increase body mass as a consequence of food consumption and plumage wettability. However, little is known about the effect of maximum extra load on takeoff of aquatic birds. Experimental evaluation of maximum load-lift during takeoff was performed on a wing-propelled diver with high wing loading, Cassin's Auklet Ptychoramphus aleuticus, and on a surface feeder with low wing loading, Leach's Storm-Petrel Oceanodroma leucorhoa. Leach's Storm-Petrel supported a maximum extra load of 45% of its body mass, and that of Cassin's Auklet was 25%. The relation of maximal load to food transport and plumage wettability indicates that the storm-petrel and the alcid maintain safety load margins of 31% and 8% of the maximum supported extra load during takeoff, respectively. Load margin showed by storm-petrels suggests an enhanced flight performance, increasing specific lift during foraging; meanwhile that of auklets allows for reduction of specific buoyancy during diving.

Arctic Terns show large variations in colony attendance between breeding seasons, making comparable counts of colony size complex and population status estimates difficult. Here, three areas in two regions of Greenland were surveyed in consecutive breeding seasons between 2002 and 2009. Between-year variation in population size in the small and mid-sized Arctic Tern colonies in West Greenland was considerable (mean CV of individual colonies 117.5%, CV of total 49.6%). In the largest colony in Greenland, Kitsissunnguit, overall colony size showed minor variations (CV 14.6%), but variation in numbers was pronounced at the sub-colony level (mean CV 47.4%). When combining the surveyed colonies in West Greenland, the total population size varied little (CV 6.7%) and less than expected if colonies fluctuated independently (P = 0.023), indicating that local movements between the colonies took place and annual variation was linked to local rather than to large-scale phenomena. In Northeast Greenland, complete breeding failure, likely caused by Arctic Fox, was recorded in two out of four seasons. Future Greenland Arctic Tern colony monitoring should either 1) survey multiple colonies within the same season covering adjoining colonies over a larger area, or 2) survey one large, representative colony in multiple years in order to track potential changes in population size.

Effective conservation and management of Bar-headed Geese (Anser indicus) require data to determine migration routes and identify key sites for protection. Ten Bar-headed Geese were banded with satellite transmitters at Qinghai Lake in western China in July 2006 and 2007 to determine their migration routes. Of the tagged geese, eight left Qinghai Lake and began autumn migration. Of these eight, four completed their autumn migration, lasting 50 to 90 days, using one of two migration routes to their wintering grounds near Caohai Lake in Guizhou Province, Yarlung Zangbo valley in Tibet, and Kohima in India. The tagged geese each stopped at three to four sites and traveled 1,270 to 1,470 km from their breeding to wintering grounds. Wetlands at Muli Marsh, Zhaling, Eling and Galalacuo Lakes in Qinghai Province, Nagqu and Damxung in Tibet, and Ruoergai Marsh in Gansu and Sichuan Provinces were used as major stopover sites.

A Great Blue Heron (Ardea herodias) foraging on an Atlantic Stingray (Dasyatis sabina) was observed off coastal Mississippi. Although elasmobranchs have been previously reported in the diets of birds, this observation was the first documenting the attack and consumption behavior by a bird on an elasmobranch. The behaviors in the event mirror previous observations of A. herodias attacking large and unwieldy prey items. Consumption of a high trophic-level fish by A. herodias further emphasizes its role as a top predator in shallow marine food webs.

Various mitigation measures have been implemented to reduce incidental seabird mortality in longline and trawl fisheries but little attention has been given to artisanal fishing. In the 2008/09 breeding season, during a study of foraging of Humboldt, Spheniscus humboldti, and Magellanic Penguins, S. magellanicus, breeding on Puñihuil islets, southern Chile, a Magellanic Penguin equipped with a time-depth recorder became entangled and subsequently drowned in a gill net set for Corvina Drum (Cilus gilberti). The device was returned by fishermen and the data appear to be the first documented case of such a drowning in a marine, air-breathing vertebrate. According to the data, while diving to a depth of more than 50 m, the bird became entangled and drowned, remaining below 60 m for nearly 21 hours until the net was hauled. Although only a single incident is reported, there are indications that incidental mortality of penguins, other seabirds and marine mammals is more common in artisanal fisheries than previously anticipated.