Population connectivity is an important consideration in studies of disease transmission and biological conservation, especially with regard to migratory species. Determining how and when different subpopulations intermingle during different phases of the annual cycle can help identify important geographical regions or features as targets for conservation efforts and can help inform our understanding of continental-scale disease transmission. In this study, stable isotopes of hydrogen and carbon in contour feathers were used to assess the degree of molt-site fidelity among Bar-headed Geese (Anser indicus) captured in north-central Mongolia. Samples were collected from actively molting Bar-headed Geese (n = 61), and some individual samples included both a newly grown feather (still in sheath) and an old, worn feather from the bird's previous molt (n = 21). Although there was no difference in mean hydrogen isotope ratios for the old and new feathers, the isotopic variance in old feathers was approximately three times higher than that of the new feathers, which suggests that these birds use different and geographically distant molting locations from year to year. To further test this conclusion, online data and modeling tools from the isoMAP website were used to generate probability landscapes for the origin of each feather. Likely molting locations were much more widespread for old feathers than for new feathers, which supports the prospect of low molt-site fidelity. This finding indicates that population connectivity would be greater than expected based on data from a single annual cycle, and that disease spread can be rapid even in areas like Mongolia where Bar-headed Geese generally breed in small isolated groups.

Nest depredation is the leading cause of waterfowl nest failures in much of the Prairie Pothole Region, USA. In 2006 and 2007, spatial and temporal patterns of nest depredation were evaluated on 248 waterfowl nests and 88 simulated waterfowl nests in North Dakota, USA. The hypothesis that predators are able to locate adjacent nests using an area-restricted search once they find the first nest and that ducks will space their nests apart to reduce this from happening was tested. However, no evidence was found to support either part of this hypothesis or that density-dependent depredation was occurring. This lack of support, along with no relationship between nest density and nest success, indicate that density-dependent depredation may not have been a problem in our study area. Artificial nests were used to test the hypothesis that meteorological conditions impact nest depredation rates. Artificial nests were more likely to be depredated when either temperature or dew point was high. It was hypothesized that these meteorological conditions increase the evaporation rate of odorants, and thereby improve the ability of predators to locate food sources by using olfaction. These meteorological conditions could also increase odor release from the surfaces of nests or incubating hens, although additional studies are necessary to determine if the relationship between evaporation rates and foraging efficiency of olfactory predators holds for natural waterfowl nests.

Sympatric nesting seabird species are often found to differ in one or more aspects of their foraging ecology. This is usually interpreted as resource partitioning, potentially due to current or past competition, but other explanations have been proposed. Three closely related species of alcids breeding together in subarctic southwest Greenland differed in several aspects of their foraging ecology during chick rearing. Thick-billed Murres (Uria lomvia) and Common Murres (U. aalge) did not differ in their diving behavior but both species differed markedly with Razorbills (Alca torda). Thick-billed Murres foraged mainly close to the colony, whereas Common Murres and Razorbills also made foraging trips to the mainland coast. Common Murres made significantly more bouts (series of dives) per trip than Thick-billed Murres, but significantly fewer dives per bout than Razorbills. Median dive depth of Thick-billed and Common murres was twice that of Razorbills. Thick-billed Murres nested on open ledges and spent most of their non-foraging time on the ledge attending the chick. Common Murres and Razorbills nested under boulders and in crevices and often left their chicks alone (particularly at night) and rested on the water. One interpretation of this pattern is that the risk of predation from Glaucous Gulls (Larus hyperboreus) was much higher on open ledges, and that Thick-billed Murres therefore had to guard their chicks at all times.

Determination of hematological and biochemical parameters provides important data to assess the physiological condition in wild birds. Therefore, to carry out ecophysiology or conservation studies it is essential to establish baseline physiological parameters and how these change with age and life history events. Hematological (hematocrit, hemoglobin and erythrocyte sedimentation) and biochemical (glucose, total lipids and proteins, aspartate and alanine aminotransferase activities and electrolyte concentration) reference values were determined in two Antarctic migratory bird species, the Brown Skua (Stercorarius antarcticus) and South Polar Skua (S. maccormicki), from South Shetland Island during breeding season. Also, hematological data (hematocrit) were determined for non-Antarctic skuas, with Chilean (S. chilensis) and Falkland (S. antarcticus antarcticus) skuas sampled in the Beagle Channel islands (Tierra del Fuego Province) and Viana Island (Chubut Province), Argentina, respectively. Differences between adult Antarctic skua species were observed in hemoglobin, erythrocyte sedimentation, total lipids and aspartate aminotransferase activity. In addition, age-related differences in Antarctic skuas in hematocrit, hemoglobin, glucose and total protein values were observed. Serum reference protein fractions (Albumin, α₁, α₂, β and γ globulins) were assessed by electrophoresis for Antarctic and non-Antarctic skuas. Similar protein patterns were observed between South Polar and Chilean skuas as well between Falkland Skua and Brown Skua. The differences between adult sympatric Antarctic skuas may be related to their nutritional status and species-specific migrations, feeding habits and the differential use of the breeding niches, while the age variation may be related to physiological development processes in chicks or to the energy expenditure in adults during breeding.

The breeding season is a demanding period in an individual's annual cycle because it must balance energy gains with the competing demands of reproduction and self-maintenance and properly allocate time and energy to both. To better understand how this balance is reached, nest-attendance patterns, food-provisioning rates, and foraging patterns were studied in radio-tagged Great Egrets (Ardea alba) breeding in a mixed-species colony in Wichita, Kansas, from May–August 2010–2013. A total 900 bird-days for 16 Great Egrets (60 ± 32 days/bird) provided 777 records of feeding sites, yielding travel times, flight velocities, and flight distances. Prey-capture rates, capture efficiencies, prey sizes and aggressive interactions were recorded at rivers, ponds, and weirs. A data logger placed in the colony from 2011–2013 recorded 3,390 arrivals and departures by 14 Great Egrets, documenting nest-attendance patterns. Provisioning intervals (196 ± 18 min [SD]; Range = 30–2,044 min) differed among radio-tagged individuals and among the three years. Round-trip distances to feeding sites in 2011 (16.3 ± 17.8 km) and 2012 (16.0 ± 7.0 km) were both were longer than in 2013 (11.1 ± 3.3 km). Flight distances to feeding sites also differed among individuals and increased with breeding stage. Strike rates (strikes/min) and capture rates (prey/min) differed by year but not by microhabitat. However, capture efficiency (successful strikes/total strikes) differed among microhabitats. Fish captured at weirs averaged six times heavier than those caught at rivers or ponds, but Great Egrets also encountered rates of aggression at weirs five to 10 times higher than at the other sites. A summary of energy gains and expenditures by radio-tagged Great Egrets is described, and differences among individual birds, among years, and across microhabitats is discussed.

Over the course of a year, rice fields display spatial and temporal differences according to farming management practices, providing a succession of habitats throughout the crop-growing cycle for various waterbird species. However, few studies have assessed the influence of the spatial and temporal differences produced by rice field farming management practices on waterbird species during a year. The present study investigated spatial and temporal patterns of species distribution and examined the factors that affect waterbird selection of foraging habitats in the rice fields located in the midwestern part of South Korea from April 2009 to March 2010 and from April 2011 to March 2012. Waterbird species represented strong seasonality and selectively used different field types at a fine spatial scale. The selection of field type depended more on field structures that were related to the vulnerability of prey items than on prey abundance in rice fields. Water level was an important factor that affected shorebird selection of foraging habitat, and they chose habitats with different water levels according to their body size. The density of rice plants was a critical factor affecting the selection of habitats by herons, because densely planted fields inhibited their access to food. The presence of rolled straw in rice fields affected the distribution of waterfowl. These results demonstrate that farming management practices, which determine prey accessibility, strongly affect the use of rice field habitats by waterbirds. Our knowledge of these relationships should be incorporated into conservation practices protecting the various waterbird species that use rice fields.

—The Spectacled Guillemot (Cepphus carbo) is a seabird endemic to northeastern Asia. It is listed as a “Vulnerable” species in Japan, though little is known of its population status. Population surveys were carried out during 2011–2014 throughout their range in northern Japan. Twenty-eight known and six suspected breeding colonies were reported in this region during 1875–2010. Fourteen known and four suspected breeding colonies were found in the 2011–2014 surveys, with 1,169 individuals and 294 nests. Based on our analysis of the two survey periods, 19 colonies have apparently disappeared, and populations have decreased in 12 of the current colonies. Our models indicated that colonies with small numbers of individuals were most likely to disappear, whereas other environmental factors (i.e., colony type, latitude, and SST trends) had relatively minimal effects on local colony extirpation. Our study shows that the population status of the Spectacled Guillemot has deteriorated in Japan.

The aim of this study was to describe the size dimorphism in adult Eurasian Coots (Fulica atra). Appropriate discriminant functions to allow efficient sex determination on the basis of morphological measurements were developed. Breeding Eurasian Coots (n = 55) were captured from the urban population in central Poland. Eight measurements were collected from each individual, and all individuals were molecularly sexed. Head length and wing length yielded the highest discriminatory power among the collected measurements, with males larger than females. Using a jackknife procedure, a combination of these two measurements correctly sexed approximately 95% of Eurasian Coot individuals. The discriminant functions developed here could be a reliable alternative to molecular sexing techniques in the Eurasian Coot.

Molt and migration can coincide in Arctic nesting waterfowl because they have little time between fledging and the severe weather that precipitates migration. Objectives were to observe how patterns in autumn and winter molt by Long-tailed Ducks (Clangula hyemalis) were influenced by nutrient reserves or seasonal life-cycle events. Molt scores and nutrient reserves were determined for birds salvaged during autumn 2011 (n = 79) and collected during winter 2002–2004 (n = 255). Differences in molt among sex-age classes and correlation between molt and nutrient reserves were determined. It was predicted that adult females and juveniles of both sexes suspended molt during autumn migration to limit energetic overlap; however, greater molt in juveniles during autumn than winter was detected. Correlation between molt and nutrient reserves were not detected. Molt was less in adult males than females and juveniles during winter, which may suggest that the effects of reproduction (females) and growth (juveniles) extended their molt into winter. Observed molt patterns are consistent with fixed cues associated with the timing of seasonal life-cycle events of this species. This could have important implications in understanding the life-cycle events of Long-tailed Ducks and provide novel explanations of seasonal molt.

Recent dramatic growth of the North American Interior population of Double-crested Cormorants (Phalacrocorax auritus) has led to concern about potential impacts of this species on co-nesting colonial waterbirds. Previous investigations of these concerns have focused on Double-crested Cormorant interactions with other species within homogeneous breeding environments, making broad patterns difficult to identify. The present study examined how nest location, nest density, and species identity mediate agonistic interactions among Double-crested Cormorants and Great Blue Herons (Ardea herodias) nesting at a colony site in central Minnesota, USA. Twenty-six Double-crested Cormorant nests and 27 Great Blue Heron nests were observed for 30 min weekly for 8 weeks during the breeding season to estimate frequency of agonistic behavior and identify species-level patterns of interaction. Most agonistic interactions observed (81%) were intraspecific interactions among Double-crested Cormorants; Great Blue Herons engaged in a higher combined total count of interspecific and intraspecific interactions when they nested near Double-crested Cormorants. Interspecific interactions were more common among ground-nesting birds than among tree-nesting birds. This study suggests that further investigation into impacts of Double-crested Cormorants on co-nesting birds is most warranted for ground-nesting colonies.

Nest success and nest-site characteristics of the Tufted Duck (Aythya fuligula) were studied during the 1996 breeding season at Loch Leven, Scotland. Approximately 463 ± 47 Tufted Duck pairs nested in association with 6,674 ± 805 Black-headed Gull pairs (Larus ridibundus) on St. Serf's Island. Tufted Ducks had an apparent nest success rate of 79.5% (Range: 65.8%–83.6%; n = 73). Multiple logistic regression was used to test the hypothesis that nest-site characteristics, such as distance to colony edge, overhead and vertical nest cover and distance to nearest Tufted Duck or Black-headed Gull nest, affect nest success. By using only the Tufted Duck nests with a known fate (n = 60), distance to the colony edge was identified as the primary predictor of nest success (P = 0.004), with successful nests (31.60 ± 1.71 m) located farther from the colony edge than those that failed (18.75 ± 2.61 m). Results support the central-periphery nest distribution model which suggests that nests located in the center of a colony, particularly in homogeneous habitats, are less accessible to predators and have greater reproductive success.

Opportunistic behavior in birds can enhance the ability of a species to expand their distribution. Currently, there is no documentation of any bird diving and feeding in hot springs with temperatures greater than 30 °C. A pair of Torrent Ducks (Merganetta armata) feeding in a hot spring with temperatures between 36–50 °C is described. The diet and food availability in this hot spring was studied in a Torrent Duck territory. While the sector of stream with hot waters represents only 13% of the territory of the Torrent Duck pair, prey collected there represented 30% of their diet. This is an extreme example of how this highly specialized species can also use a wide variety of environments.