Understanding the composition and abundance pattern of species across sites is a central question in community ecology. However, the structure of waterbird assemblages in fragmented wetlands has been poorly documented. We carried out twelve monthly censuses to describe the composition and abundance patterns in 42 wetland fragments and two lagoons in the coastal zone of Rio Grande do Sul, South Brazil. A total of 142,000 birds from 66 species, 18 families and 18 orders were recorded. Most species were either resident (29) or partial migrants (19). All migrant species (8 nearctic, 4 austral and 5 summer breeders) were recorded in small numbers and most of them were restricted to lagoons. The lagoons had more species (60) than the wetland fragments (55), even though the total fragment area (1,426 ha) was about twice the censed area in the lagoons (743 ha). Principal Coordinate Analysis revealed strong temporal and spatial gradients of abundance and composition that were similar in fragments and lagoons. The number of species varied among sites and showed no seasonal pattern. Abundances were higher in the wintering period (min. of 2,500 birds in March and max. of 23,000 in July) due to the increased abundance of Gruiformes and Anseriformes. The White-faced Whistling-duck (Dendrocygna viduata) and the Common Moorhen (Gallinula chloropus) were the most abundant and frequent species over the year, comprising together 69% of the total. The census captured 76% and 60% of the waterbird species listed for the region and the Rio Grande do Sul State, respectively. The study area shared more than 90% of the species with the nearby States and 76% with the Pantanal region. The beta-diversity among sites was 94% when only fragments are considered, and 38% when the lagoons are included in the calculation, showing that a great proportion of the waterbird richness at the landscape scale is accommodated as a beta component. The local abundance and composition of waterbird assemblages seemed to be affected by the interplay of several factors, including the rich regional pool of species, their wide range, the fragment area, the surrounding matrix and the presence of core refuges. A landscape perspective is essential on building sound conservation programs for waterbird assemblages.

Roseate Tern (Sterna dougallii) nests were monitored at Falkner Island, Connecticut, USA between 1998 and 2002. A total of 586 chicks were sexed and their growth measured during the first three days. These data were used to derive growth parameters and predict survival to fledging with high confidence. In contrast to a previous study in Massachusetts, we found no sex-ratio bias at hatching in any single year or in all years combined, nor was there a bias at fledging in all years combined, or in any single year. This difference is interesting because both colonies exhibit a female-biased sex ratio at breeding. After controlling for other factors, there was no difference in early growth or survival between male and female chicks, consistent with our previous studies and with the hypothesis that differences in growth and survival between males and females observed in other species are due to sexual size dimorphism.

Comparisons were made of the foraging ecology of Caspian Terns (Sterna caspia) nesting on two islands in the Columbia River estuary using radio telemetry and observations of prey fed to chicks and mates at each colony. Early in the chick-rearing period, radio-tagged terns nesting at Rice Island (river km 34) foraged mostly in the freshwater zone of the estuary close to the colony, while terns nesting on East Sand Island (river km 8) foraged in the marine or estuarine mixing zones close to that colony. Late in the chick-rearing period, Rice Island terns moved more of their foraging to the two zones lower in the estuary, while East Sand Island terns continued to forage in these areas. Tern diets at each colony corresponded to the primary foraging zone (freshwater vs. marine/mixing) of radio-tagged individuals: Early in chick-rearing, Rice Island terns relied heavily on juvenile salmonids (Oncorhynchus spp., 71% of identified prey), but this declined late in chick-rearing (46%). East Sand Island terns relied less on salmonids (42% and 16%, early and late in chick-rearing), and instead utilized marine fishes such as Anchovy (Engraulis mordax) and Herring (Clupea pallasi). Throughout chick-rearing, Rice Island terns foraged farther from their colony (median distance: 12.3 km during early chick-rearing and 16.9 km during late chick-rearing) than did East Sand Island terns (9.6 and 7.7 km, respectively). The study leads to the conclusion that Caspian Terns are generalist foragers and make use of the most proximate available forage fish resources when raising young.

The largest and most productive colony of Snow Geese (Chen caerulescens caerulescens) in Alaska for two decades (1980-1999) was on Howe Island in the outer Sagavanirktok River Delta. Petroleum development began in this area during the mid-1980s, and studies of Snow Geese on Howe Island were conducted annually since 1980. Annual gosling production remained high and the colony expanded during 1980-1993; thereafter both gosling production and colony size declined. During 1980-1993, gosling production was highly and positively correlated with mean daily air temperature during the 1-25 June incubation period, and predation at the colony was insignificant. After 1993, there was an increase in predation on Snow Goose eggs at Howe Island by Grizzly Bears (Ursus arctos) and other mammalian and avian predators, which resulted in the decline of the Howe Island colony. New Snow Goose colonies east of the oil fields expanded during the decline on Howe Island. Evidence suggests that this eastward expansion likely resulted from dispersal or displacement of geese from Howe Island. After 1993, the effects of predation confounded the known effects of spring temperatures, and predation became the significant factor influencing gosling production. Increased predators in the Prudhoe Bay area and at Howe Island were suspected to be linked to the availability of human food waste and refuse and to the cessation of hunting and trapping in the area. Recently imposed mitigation measures have included better refuse and waste management and removal of problem bears. These measures should result in reduced predation and increased productivity at the Howe Island Snow Goose colony.

Searches for color-banded Great Cormorants (Phalacrocorax carbo) were carried out during 2002-2004 at an inland roost in Spain in order to determine the origin of the birds, to measure the length of stay and within- and between-seasons site fidelity in relation to age. Contrary to expectations, neither the stay duration at the roost nor the site fidelity depended on age. The low stay duration (the majority of the birds were sighted only once) and return rates suggest nomadic behavior of the wintering cormorants. The cormorants that stayed longer at the roost also returned there more times during one season, suggesting that site fidelity may have an adaptive value for wintering cormorants.

Surveys of the American Oystercatcher (Haematopus palliatus) were conducted in all suitable nesting habitat in coastal Virginia, USA during the 2003 breeding season. The total of 588 pairs more than doubles previous estimates for the state, and provides a benchmark for the comparison of future surveys. These results suggest that Virginia supports the largest number of oystercatchers in the breeding season relative to other east coast states. Previous surveys in Virginia focused only on one coastal area, the barrier islands. Over two hundred pairs recorded in the seaside lagoon system of the Delmarva Peninsula in 2003 accounted for the large discrepancy between previous estimates for the state and the results of this survey. Over 89% of the total number of pairs was observed on the islands and in the lagoon system of the Delmarva Peninsula. Approximately 87% of the pairs were on land that is managed or regulated to some degree for the conservation of nesting birds by federal, state, municipal and non-governmental organizations, including 20% that occurred on land closed to public use during the bird-breeding season. Only 13% of the pairs were on land that affords no protection to breeding birds.

Diurnal activities and foraging methods of juvenile, parent (adults with young), and non-parent (adults without young) Tundra Swans (Cygnus columbianus) were measured during autumn and spring migration at Long Point, Ontario, to evaluate: 1) age-related differences in activities and feeding methods of family members, 2) potential short-term behavioral costs and benefits of prolonged parent-offspring association, and 3) several predictions based on predation risk and swan social structure. Vigilance of inactive parents and juveniles declined as flock size increased at observation sites. However, other evaluations of vigilance in active (and inactive parent/non-parent) swans and use of risk-prone foraging methods did not support the hypothesis that swans respond to reduced risk of predation resulting from membership in larger flocks. These results may be due to their use of inaccessible aquatic habitats and their large relative size, both of which relate to their lack of natural predators, at staging areas. Both parents and young used sub-surface feeding methods to the same amount, but parents “treadled” more than did juveniles and juveniles “dabbled” more on the surface than did parents. These findings suggest that some degree of resource partitioning exists between parents and young or possibly parents indirectly facilitate feeding activities of their young. Parents were more vigilant and interacted with other social groups more than did juveniles, but their feeding activity was unaffected as both parents and juveniles spent similar time foraging. Time spent vigilant, in intraspecific interactions, and feeding was similar between parents and non-parents. Based on this evidence, parents did not appear to incur short-term behavioral or energetic costs of prolonged association with young. However, both parents and juveniles likely benefited from higher social standing associated with family status or larger family size.

The commensal association of waterfowl with foraging swans (Cygnus spp.) was studied in southernmost Sweden. Among more than 1,500 Mute Swans (C. olor) only 2.6% had attending waterfowl whereas 41% of Whooper Swans (C. cygnus) and 51% of Tundra Swans (C. columbianus bewicki) had associated commensals, no doubt because of the species’ different feeding techniques. Four species of commensals occurred at the main study site, Eurasian Wigeon (Anas penelope), Mallard (A. platyrhynchos), Pochard (Aythya ferina) and Common Coot (Fulica atra), wigeon making up about a third of the individuals. A mean of 3.4 waterfowl attended each Whooper Swan. Aggression was common among the commensals, with intraspecific aggression being more common than interspecific aggression in both wigeon and Pochard, and apparently influenced the size and composition of the groups and also the individuals’ positions relative to the swan. The preferred position just behind the swan was defended by threats and attacks. Although wigeon in this position did not have higher pecking rates they obtained significantly more large items than wigeon farther behind the swan.

We retrospectively conducted a survey of blood lead levels in Mute Swans (Cygnus olor) admitted to a Royal Society for the Prevention of Cruelty to Animals wildlife centre with injuries caused by collision with power lines or other overhead cables. Of 72 birds admitted over a three-year period, four birds were dead on arrival and 14 were euthanased on arrival due to severe injuries or burns. Of the surviving 54 birds, 43 were sampled to determine blood lead levels and 63% of these had elevated lead levels (>1.21μmol/l). We also blood sampled 260 swans admitted with symptoms consistent with exposure to lead that had not been involved in collisions and 620 birds admitted for all other reasons that had also not been in collisions. There was no significant difference in the proportion of collision birds with low (<1.21μmol/l) or intermediate (>2<5μmol/l) lead levels compared to non-collision birds. However, a significantly larger proportion of birds admitted following collision with power lines had moderately elevated blood lead levels (1.21-2μmol/l) compared to non-collision birds and a significantly smaller proportion had high blood lead levels (>5μmol/l). Adults accounted for 72% of admissions following collision and there was no significant difference between the proportion of collision and non-collision birds that were adults. Our data suggest that birds with elevated but moderate blood lead levels suffer an increase risk of collision, while those with intermediate to high levels have a much reduced risk of collision, possibly because they are too weak to fly. Inexperience does not appear to be a significant factor in determining the risk of collision.

The highly herbivorous Gadwall (Anas strepera) is the most salt-tolerant of the North America dabbling ducks and typically breeds in wetlands where salinity does not exceed 15. Small numbers also breed at hypersaline (80-90) Mono Lake, California, which lacks vascular plants. There, Gadwall raise young on the open lake, feed nearly exclusively on alkali flies (Ephydra hians), and minimize osmotic challenges by concentrating activities in areas with access to fresh water. Fledging success is high as a result of abundant food and low predation, but is evidently offset by poor survivorship among postbreeding adults. Failure to complete wing molt and, perhaps, foot disease are implicated. Food in the lake remains abundant well into the autumn. Nevertheless, local birds leave as soon as the young fledge. Many move to nearby freshwater lakes before eventually before continuing to wintering locations in the Central Valley of California. Migrants avoid Mono Lake at this season in favor of nearby freshwater lakes. Overall, Mono Lake’s value for breeding and migrating ducks is low, because of harsh water chemistry, limited fresh water for drinking and marshes for feeding, and apparent low survival among adults.

Distributional and dietary responses of wintering Steller’s Eiders (Polysticta stelleri) to spring spawning of Baltic Herring (Clupea harengus) were studied along the Lithuanian coast of the Baltic Sea. Herring spawn is patchy, but is abundant and energy-rich when present. The objective of this study was to determine whether Steller’s Eiders modified their foraging sites and food habits to take advantage of spawn, or whether they were inflexible foragers as suggested by earlier studies. Steller’s Eiders altered their habitat use during herring spawn, moving to habitats where fish spawning occurred. Also, diet analysis demonstrated that herring eggs became an important food when available. Although the importance of herring spawn for Steller’s Eiders remains speculative, this study indicates that spawning sites could be important as a source of nutrients and energy for subsequent migration or reproduction, and should receive conservation consideration.

Some species in the family of grebes (Podicipedidae) are gregarious and nest in extensive colonies, others are solitary breeders aggressively defending their territories. Others, including the Great Crested Grebe (Podiceps cristatus), can breed in colonies or as solitary pairs, suggesting that individuals are able to change from a solitary strategy to a more social pattern. This paper concentrates on observations during colony establishment and nesting in a colony of Great Crested Grebes near Lake Ijssel in the Netherlands. The arrival of the grebes at the colony and their egg laying was spread over a long period. From the start, the breeding birds tended to use the entire area of the vegetation available for building nest platforms and this led to a progressive reduction in the distances between neighboring pairs. The final nesting density was extremely high, with 14.3 nest platforms per 100 m². On average, each nest held 3.75 eggs. The crowded nesting of the Great Crested Grebe was imposed upon the birds because of the absence of sufficient suitable nesting habitat. It is suggested that the extent of aggregation is dictated by the quality of the site and the ability of the grebes to reduce their aggressiveness towards one another. Social behavior did not primarily contribute to the breeding aggregation.

The feeding ecology of the Kelp Gull (Larus dominicanus) was studied during the 2002-03 breeding season at Coquimbo, northern Chile. Food composition was studied by analyzing pellets regurgitated by Kelp Gulls living in different habitats. Birds breeding or resting near fishing ports used these as their main feeding grounds. Birds breeding on offshore islands fed mainly on intertidal organisms and olives. A comparison between the food of breeders and non-breeding birds during the breeding season showed a difference in diet composition of breeders, who fed more on fish of high energy density while non-breeding birds continued feeding on a wide range of organisms and waste. Observations in a fishing harbor and at sea demonstrated that fisheries waste was an important food source for the birds. The inshore distribution at sea was related to the location of fishing ports and breeding colonies.

During 1999-2002, we studied the abundance of fish-eating birds, primarily Ring-billed Gulls (Larus delawarensis) and California Gulls (L. californicus), and estimated their consumption of fish at Horn Rapids Dam and the Chandler Irrigation Canal return pipe on the Yakima River in eastern Washington. Earlier observations of gulls at these structures suggested a high level of predation of juvenile salmonids. The relationship between river flow, gull use at the sites and fish taken was also examined. Numbers of gulls (instantaneous counts of foraging and non-foraging individuals) at the structures varied daily between their arrival in late March-early April and departure in late June. Daily averages across the four years were 9.8 (SE ± 1.5) and 19.1 (SE ± 2.5) gulls at Horn Rapids and Chandler, respectively. Gull numbers at Horn Rapids peaked dramatically during the last two weeks in May, reaching maxima of 37 (SE ± 2.2) to 133 (SE ± 4.2) gulls/day. This increase appeared to be associated with the hatchery release of one to two million juvenile autumn Chinook (Oncorhynchus tshawytscha) above the dam. A comparable peak in gull abundance was not observed at Chandler. Diurnal patterns of gull abundance differed between sites and among years. Relationships between fish take and water flow also varied within and among years at the two sites. Low seasonal flows were associated with increased predation at Chandler, whereas high seasonal flows were associated with increased predation at Horn Rapids. Assuming all fish taken were salmonids, consumption at both sites combined was estimated to be ≤10.3% of the juvenile salmonids passing the two sites.

We studied numbers and productivity of the European White Stork (Ciconia ciconia) during 1968-2002 at Kłopot village colony (in the Odra River valley, Poland) and their response to water level and livestock farming. The number of nesting pairs (range 19-33) fluctuated independently of the April and June water level, but correlated with the presence of a local livestock farm. The average number of chicks fledged per pair was negatively correlated with the water level in April, when White Storks choose the breeding area. The White Stork appears to use farming activity rather than water level in making a decision as to where to a settle. This result suggests that changes in management practices, which are relatively easily made, may improve demographic parameters of local breeding White Storks.

The importance of the lower Rahway River, New Jersey, to wading birds was investigated, and foraging patterns and interspecific differences in wading bird microhabitat use are described. Foraging decisions by wading birds are complex and occur at several levels. In order to examine foraging decisions at the habitat and microhabitat levels, 79 censuses were conducted by boat along a 5-km tidal section of this river in 1988, 1998, 1999, and 2002. The locations of 1,148 birds were recorded on maps, and patterns of microhabitat use were determined. Overall, year, date, and tide level were important predictors for the numbers of wading birds that were recorded. However, each species responded to a different combination of variables: for Great Egret it was year and date; for Snowy Egret date and tide level; and for Glossy Ibis year, date, and tide level. Tide flow direction was not important for any species. For all three species, spatial distributions long the river were clumped rather than uniform, which were associated with physical characteristics along this section of the river. All three species used the mouths of narrow tidal creeks more frequently than expected, but species differed in the use of mudflats and areas of slow-moving water. There was little overlap among species in spatial distribution along the river, but the overall use of microhabitats was broadly similar. This study suggests that the lower Rahway River estuary in New Jersey is valuable to local wildlife and should be considered in future development plans.

Available information on the breeding biology of the Great Bittern (Botaurus stellaris) is poor. New data are presented on nest description and distribution, breeding phenology, clutch and brood sizes, egg biometrics and breeding success, based on 27 nests at one French and three Italian sites. Nest shape and breeding phenology appeared at least partially linked to environmental factors. Breeding success was studied for the first time to the fledging stage using radio-tagging young. About 30% of eggs produced fledging young, and it is suggested that starvation was the main cause of chick death. Young moved away from the nest when about 15-days old and extensive dispersal occurred within 2-3 weeks from independence. A survey of the literature indicates variability in several breeding parameters and suggests that the Great Bittern is an adaptable bird.

On islands in the Gulf of California in 2003 and 2004, we recorded three Blue-footed Booby (Sula nebouxii) and one Brown Booby (S. leucogaster) nests that were actively used by two females and one male. Although our data are limited, and cooperation cannot be completely ruled out, we suggest that these nests were the result of bigamous behavior.

Common Murre (Uria aalge) breeding success has been monitored in 1996-2004 at Devil’s Slide Rock, California as part of a restoration project related to the Apex Houston oil spill. During the 2001 breeding season, two separate cases of egg recovery by parent murres were observed. During the first event an egg was secured and incubated 60 cm from the original nesting site, while in the second case an egg was retrieved after rolling 85 cm. The first egg was lost within 24 hours, and the second disappeared within a day of its expected hatching date. We describe the circumstances surrounding these events, including the behavior of the parent murres during the egg recovery attempts, the subsequent fate of the recovered eggs, the microhabitat features associated with egg loss and other factors affecting the egg recovery ability of adult murres.