Multiple species of shorebirds are now globally threatened, particularly across tropical Asia, yet we know relatively little of the detailed habitat usage and resource characteristics of sites in the region. The objective of this study was to determine how seasonal variation in food density affected foraging patterns and body weights of Long-toed Stint (Calidris subminuta), a relatively common winter visitor. Research was conducted during the passage and overwintering seasons in wastewater treatment ponds and salt-pans on the Inner Gulf of Thailand. Predictions were that during periods of higher food density, shorebirds should be relatively more abundant and heavier, and have increased foraging attempts, reduced step rates and reduced chase rates. Furthermore, adults were expected to have higher weights than juveniles. Overall, shorebird abundance was significantly positively correlated with invertebrate abundance during the 2-year study period. Long-toed Stints had greater body mass following their arrival in July-September, compared with later periods during the winter. Although food density and Long-toed Stint step rate were not significantly correlated, the data were consistent with previous studies suggesting a negative relationship. Step rates in salt-pans were significantly higher than in the wastewater treatment ponds, probably reflecting lower food densities in the salt-pans. There was no clear relationship between food density and Long-toed Stint peck rate, perhaps reflecting the weak correlation between number of pecks and the number of successful foraging bouts as well as limited sample sizes for prey estimates. There was no significant relationship between food density and chase rates. There was no significant difference in median body mass between adults and juveniles/first-year birds, implying young birds learn to forage as efficiently as adults relatively rapidly. This study suggests that further work on invertebrate dynamics and shorebird diets in the region is needed in order to build more predictive models of shorebird site usage and population dynamics.

Activity patterns of fledgling storks (Ciconiidae) during the parental-dependency period are poorly understood for many species, including the Wood Stork (Mycteria americana). Satellite telemetry was used to track the movements of fledgling Wood Storks ( n = 50) from the time they attained minimum flight capabilities until dispersal from the natal colony. Distances traveled, range size, and habitat use by fledgling Wood Storks were quantified for early (prior to the final week before dispersal) and late (the final week before dispersal) predispersal periods and for the entire predis-persal period as a whole. Metrics were compared among three colonies and between two years at a single colony using nonparametric tests. For the entire predispersal period, the mean daily maximum distance of juvenile Wood Storks from their nest was 1.39 ± 0.2 km (median = 0.18 and maximum = 103.13) and the mean cumulative distance moved per day was 2.38 ± 0.28 km (median = 0.45 and maximum = 110.58). Movement distances differed among colonies and between years, while core and total ranges were similar regardless of location. The majority of locations (84%) occurred within colony boundaries, 95% occurred within 1.0 km of the colony and 98% occurred within 3.5 km of the colony. Flight distances did not increase linearly with time and instead followed a Poisson distribution, increasing sharply during the final week before dispersal. Habitat management recommendations for juvenile Wood Storks are to preserve wetland features within a 1.0–3.5 km zone around a colony.

Marbled Godwits (Limosa fedoa) do not present obvious sexual dimorphism, although females are known to be slightly larger than males, on average. During the nonbreeding seasons between August 2007 and April 2009, a noninvasive technique was tested that might permit phenotypic identification of sex in a large sample of individuals from the most important wintering area, Guerrero Negro, México. Blood samples (n = 577) were used for molecular sexing. For phenotypic sexing, culmen length was selected because it had the greatest sexual dimorphism. A normal distribution curve for culmen length of each sex and the overlapping area between the two curves was calculated and used to minimize the probability of error in identifying the sex of each individual. Using the criterion that males had a culmen length ≤ 106 mm and females ≥ 108 mm, the sex of 96.4% of the individuals would be correctly identified, 2.8% would be regarded as indeterminate and 0.8% would be sexed erroneously. A discriminant analysis using bill length and other commonly used phenotypic measurements did not improve success in predicting sex. The results indicate that culmen length is a useful measure for sex determination in Marbled Godwit. Identification of the sex of Marbled Godwits in the field offers new possibilities to study life histories of both sexes. In Guerrero Negro, the sex ratio of Marbled Godwits was heavily male-biased biased (2:1), suggesting latitudinal segregation by sex.

Species that undergo simultaneous flight-feather molt are susceptible to mortality during the flightless period. Remigial molt was examined in non-breeding Western Grebes (Aechmophorus occidentalis) and Clark's Grebes (A. clarkii) using beachcast carcasses from California to Washington to determine w^rhere and when molt occurs and help identify regions of maximum risk. Molt occurred in 18% of individuals and in all age classes and months examined, including winter, not previously recognized as a significant period for Western and Clark's grebe molt. Molt was encountered in all regions, with the highest proportions in Oregon/Washington during fall (35%), and central (18%) and southern (17%) California during winter. The percentage of Western and Clark's grebes in molt collected during the first 3 days of an oil spill was greater than later in the response (27% vs. 12%), suggesting a greater vulnerability to oiling during this part of their life cycle. Oil spills and other mortality events can provide insights into avian biology not otherwise available, and knowledge of molting regions can minimize wildlife impacts of spills through prevention and response. Received 15 November 2012, accepted 6 August 2013.

Seabird movements during foraging trips and their preference for particular areas have recently been the focus of many studies aimed at gaining a better understanding of the ecological requirements of several species. During the last decade, the use of new devices, such as Global Positioning System (GPS) devices and geo-locator loggers, has allowed researchers to perform more investigations of this type. GPS devices were used on Wedge-tailed Shearwaters (Puffinus pacificus) breeding on Aride Island, Seychelles, to identify the main foraging areas used during early chick-rearing and to assess at-sea foraging habitat selection. Thirteen foraging trips were recorded, 61.5% of which lasted 1 day. One main foraging area, located approximately 100 km east of the colony just outside a granitic bank characterized by upwelling and higher values of primary production compared to surrounding areas, was identified. The foraging area size (3,313 km²) was much smaller than that identified during late chick-rearing (160,000 km²) in a previous study. This is probably due to the exigency to feed chicks more regularly and hence to find foraging areas closer to the colony during the early chick-rearing. The identification of key marine conservation areas, like those identified in this study, is a priority for designating marine Important Bird Areas and identifying habitat management measures. The results of this study should be relevant for the development of conservation plans for Wedge-tailed Shearwaters and for other seabirds in the area. Received 11 May 2013, accepted 8 July 2013.

Sexual dimorphism is the phenotypic difference between males and females of the same species, characterized by different body size and plumage. Black Skimmers (Rynchops niger, n = 44 adults, n = 14 juveniles) were captured between December 2010 and April 2012 with mist nets during the non-breeding period in the Lagoa do Peixe estuary, southern Brazil. Black Skimmers showed conspicuous sexual size dimorphism, with males being significantly larger than females. Males were 29% heavier than females and significantly larger in six measurements (% sexual size dimorphism = 7–26%). We developed two discriminant functions, both correctly identifying the sex of > 97.7% of the individuals tested and found that head bill length alone was sufficient to predict the adult sex. The preferred habitat of Black Skimmers in this area was the barra region of the Lagoa do Peixe, where they can take advantage of the abundance of fish in the shallow water. Active molt was recorded in 62.5% of captured Black Skimmers. The molt scores of the primaries and the capture date showed a positive correlation, with lower scores observed in November/December and the highest scores in March/April. We found the intensity of red coloration of the culmen was not a good method for Black Skimmer sex determination in the field compared to molecular sexing, misclassifying 31.0% of individuals overall.

The present study describes the breeding biology of Crab Plovers (Dromas ardeola), a little-known shorebird species nesting on Nakhilu and Omol-Karam Islands located in the Nakhilu Marine National Park in the northern Persian Gulf, Iran. This study occurred during the breeding seasons of 2009–2011. Colonies had between 500–1,500 nests and were located on sand banks 1–3 m higher than the surrounding ground in non-overlapping areas. Burrow digging began in mid-April, and single nests were built in 2.82 ± 0.1 days (Range = 2–4 days, n = 45) in a period of 10.5 ± 0.76 days (Range = 8–13 days, n = 6), although a spread of digging and laying of 87.50 ± 2.96 days (Range = 82–94 days, n = 4) was recorded primarily due to renesting after human damage to the burrows. Range in nest densities was 0.14–0.26 nest per m². The clutch size was 1.01 ± 0.005 (Range = 1-2, n = 421). Egg size (n = 47) was 64.05 × 44.04 mm with an average incubation period of 33 days (Range = 31–35, n = 21). Hatching success was 63–81%, with failures primarily due to egg collecting by local fishermen and tourists. An estimated of 7 weeks passed between hatching and fledging. Fledglings had almost fully developed wings (83% of adult wing length) and feathers, but very low weight (about 55% of adult weight) and smaller bill length (only 60% of adult bill length). A stronger control of visitors and local fishermen would benefit the breeding population of Crab Plovers on the islands.

Water Rails (Rallus aquaticus) are a reliable indicator of overall habitat quality and are considered an umbrella species for reed bed habitat (Phragmites australis). Two methods of acoustic monitoring of Water Rails were tested. Ten observation points situated 100 m from each other inside a large reed bed were selected for acoustic monitoring. Observations were conducted in three sessions (end of April, June and September 2010) for three times a day, during 3 consecutive days. The number of individuals calling was quantified during spontaneous vocal activity for 5 min and then the number of Water Rails calling after exposure to digital playbacks of male and female territorial and courtship calls for 30 sec were recorded. To calibrate the data, all Water Rail nests within 100 m around three observation points were located. The number of nests found during the nest searches corresponded to the number of pairs estimated during spontaneous vocal activity, but was 63% larger than the number estimated after playback. A statistically significant difference was found between the number of calls recorded at different times in session 1; however, no significant differences were found between sessions 2 and 3. The highest numbers of individuals were recorded in the morning in session 1. The difference was statistically significant between morning and noon (P= 0.002), but not between morning and evening (P= 0.289). Population evaluation and monitoring of Water Rails in large reed beds should be done in the morning, during the breeding season, using point surveys and listening for 5 min for spontaneous vocalizations. This method can be used both for quantifying and monitoring populations of Water Rails and for evaluating the quality of its habitat.

The distribution and abundance of Yellow-billed Terns (Sternula superciliaris), Large-billed Terns (Phaetusa simplex) and Black Skimmers (Rynchops niger) were estimated, and the effects of habitat features on site occupancy by colonies of these three species nesting in the Anavilhanas Archipelago, Amazonas, Brazil, were examined. Individuals were recorded on beaches during the 2008 and 2009 breeding seasons, with 26 (2008) and 30 (2009) potential nesting beaches (sites) surveyed. In both years, one site included 28% of all the Yellow-billed Terns, while two sites included 65% of all the Large-billed Terns. Site occupancy, the probability that a site is occupied (range ψ;), was moderate to low for all three species, but higher for Yellow-billed Terns (0.58–0.63) than for Large-billed Terns (0.40–0.50) and Black Skimmers (0.23–0.54). Yellow-billed and Large-billed terns and Black Skimmers generally nested on larger beaches on islands that had little vegetative cover and that were exposed to open water, remote from river margins, distant from other islands and closer to large colonies of the same species. Abundance estimates (individuals per breeding season in the archipelago ± SE) in 2009 varied considerably among species (Yellow-billed Terns: 192 individuals ± 1; Large-billed Terns: 80 ± 1; Black Skimmer: 31 ± 1). These results suggest that habitat features that influence breeding site use by Yellow-billed and Large-billed terns and Black Skimmers include physical and vegetation characteristics as well as social attraction. While the probability of site occupancy increased with measures related to beach size and geographical isolation, closeness to large colonies indicates the relevance of social interactions for these species and, as such, the importance of large areas for the occurrence of their colonies.

Detailed information on bird populations and wetland habitats is highly important for future conservation and management activities. More than 50% of natural wetland habitats have been lost or degraded due to human intervention, which has negatively affected wetland-dependent bird populations. In this study, the density, diversity and feeding guilds of various bird species in an artificial wetland habitat were examined using a distance sampling point count technique. A total of 20,010 individuals of 102 species representing 40 families were detected from March 2009 to June 2010. In all, 64 species were counted with 72.5% of 14,520 individuals residents, 22 species were counted with 26.4% of 5,290 individuals resident-migrants, 13 species were counted with 1.0% of 196 individuals migrants and three species were counted with 0.1% of four individuals counted vagrants. Resident birds were present at the highest density and vagrants at the lowest. The most dominant migrant, resident and resident-migrant species were the Oriental Reed Warbler (Acrocephalus orientalis) (0.37 ±0.10 birds ha^-1), Rock Pigeon ( Columba livia) (3.91 0.97 birds ha^-1) and Purple Heron (Ardea purpurea) (1.55 ± 0.93 birds ha^-1), respectively. The community structure of resident birds was the most diverse and rich compared to migrants, resident-migrants and vagrants. Frugivore/insectivore (1.04 ± 0.20 birds ha^-1) was the most dominant feeding guild for migrants, nectarivore/insectivore (0.64 ± 0.04 birds ha^-1) for residents and omnivore (0.28 ± 0.03 birds ha^-1) for resident-migrants. The findings of this research indicate that artificial wetlands can provide an alternative habitat for the foraging and breeding activities of different bird assemblages.

Little is known about movements and habitat use of Brown Pelicans (Pelecanus occidentalis) in the northern Gulf of Mexico. We attached satellite transmitters to 18 adult Brown Pelicans (nine males, nine females) that were captured on Grand Isle along the Louisiana coast during 31 August–2 September 2010. Their movements and habitat use were tracked between September 2010 and March 2012. Nine of the Brown Pelicans remained proximate to the Louisiana coast; four ranged along the coasts of Alabama, Mississippi, and Louisiana; three moved from Louisiana to Texas; and two migrated across the Gulf of Mexico to the Yucatan Peninsula. Annual 99% home range estimates varied widely ( x??? = 10,611 km², SE = 2,370), and males had larger ranges (x??? = 15,088 km², SE = 2,219) than females (x??? =6,133 km², SE = 1,764). Habitats used by Brown Pelicans were primarily open water, estuarine emergent wetland, grassland, unconsolidated shore, and deep water habitat types.

The Long-billed Murrelet (Brachyramphus perdix) was previously considered to breed in Hokkaido, Japan, but the single 1961 historical nest record was recently found to be invalid, and small numbers observed during at-sea surveys off northeastern Hokkaido in 1996–2001 did not suggest breeding. In the Iburi Region of southern Hokkaido, small numbers of Long-billed Murrelets were observed at sea in May 2010 (n = 8) and May 2011 (n = 4), reflecting either local breeding, a stopover site during migration, or non-breeding individuals south of the breeding range during the breeding season. Single Long-billed Murrelets also were observed in October and December 2011, representing movements after the pre-basic molt. A historical record of a juvenile found in the forest about 20 km inland near the Chitose River in either 1913 or 1915 provides evidence of historical breeding in the Iburi Region and the best evidence so far of breeding in Japan, although breeding also may occur in the nearby southern Kuril Islands. At-sea and forest surveys are needed to better establish the status of and help conserve this declining species in the Iburi Region and other parts of Hokkaido.

Recently, the Carlos Anwandter Nature Sanctuary (Sanctuary) at the Cruces River, Chile, has undergone important ecosystem changes. Brazilian waterweed (Egeria densa), the main food resource of Black-necked Swans (Cygnus melancoryphus), has greatly decreased in abundance. This disappearance may have affected the abundance of Black-necked Swans within the Sanctuary; however, the variation in the Black-necked Swan population is still poorly understood. Spatiotemporal variation in population abundance and feeding/breeding ecology of Black-necked Swans was analyzed in the Sanctuary and adjacent wetlands (non-protected areas outside the Sanctuary) from 2000 to 2010. Temporal fluctuations in Black-necked Swan abundance were recorded, with increases in population size from late December to early June and decreases from late June to late September. Five main feeding grounds that were devoid of Brazilian waterweed were identified. However, several other aquatic plants were recorded on these grounds, suggesting that these areas provide alternative food resources for Black-necked Swans. Changes in the reproductive timing of Black-necked Swans throughout the 10-year study were recorded; no reproductive events occurred between 2004 and 2006, and a shortened reproductive period occurred between 2006 and 2010. In addition, there were changes in the locations of the breeding grounds as well as in the number of nests and chicks recorded during the study period. These results revealed new patterns in Black-necked Swan population trends as well as their distribution in areas both inside and outside the Sanctuary. Thus, to ensure effective conservation of this species requires the integration of protected areas within as well as non-protected areas outside the Sanctuary.