North America's northernmost, sizable colony of Caspian Terns (Hydroprogne caspia) is located on the Copper River Delta of south-central Alaska, USA. The colony was monitored in June during 2008-2016 and in July during 2009-2013. This 9-year period coincided with reduction of Caspian Tern nesting habitat at East Sand Island in the Columbia River estuary, Oregon, USA, one of the world's largest Caspian Tern breeding colonies. The number of active nests on the Copper River Delta more than doubled during the early study period from 209 in 2008 to 423 in 2013. However, there was a steady decline in the number of nests during 2014 (281) to 2015 (115) and the colony failed in 2016. These declines were likely due to warm sea surface temperature anomalies across the northeastern Pacific Ocean in those years. Based on resightings of banded individuals, colony connectivity was documented between the Copper River Delta and other colonies, ranging from southeast Alaska (215 km) to central California, USA (> 3,000 km). The East Sand Island colony was the most important source of immigrants to the Copper River Delta. While the Copper River Delta now serves as important natural breeding habitat for Caspian Terns, increased flooding and severe storms associated with climate change will likely limit colony size and productivity in the long-term.

Staging, an essential part of shorebird migration, is when birds concentrate in large numbers to rest and refuel. Abundance estimates at key staging sites offer promise to monitor many transient migrant populations; however, stopover chronology is needed. Point counts were conducted of all shorebirds staging at Chaplin and Reed Lakes, Saskatchewan, Canada (May-June 2014-2017). Stopover durations of individual Sanderlings (Calidris alba) were obtained using automated radio telemetry of individual Sanderlings tagged both locally and in the Gulf of Mexico (April-May 2015-2017). Seventeen Arctic-breeding shorebird species were recorded during point counts. Sanderlings were the most abundant and reached peak numbers during the last week of May. Estimates of Sanderling stopover duration varied by year and estimation method: “true stopover duration” (radio-tagged in Gulf of Mexico with known arrival and departure) was 11.1 days (95% CI = 8.6-13.6); “minimum stopover duration” (radio-tagged at Chaplin Lake with unknown arrival but known departure) was 11.9 days (95% CI = 11.1-12.7); and “estimated stopover duration” (Pradel Survival and Seniority models) was 19.9 days (95% CI = 17.5-22.7). Assuming an average 11-day stopover, we estimated ∼75,000 Sanderlings (Range = 56,000-91,000) or 12% of the global population use this site during spring migration. These findings highlight the importance of accurate migration chronology to monitor Arctic-breeding shorebird populations.

The effectiveness of islet creation and restoration on Pied Avocet (Recurvirostra avosetta) nesting was assessed in 14 ponds (six managed islets of 140 m² on average per managed pond) from a salt pan complex located on the coast of the Loire-Atlantique department in northwest France. A Before-After-Control-Impact design using the two years before and the two years following management was used. No nesting occurred in the control ponds that lacked suitable islets. In the managed ponds, the mean number of nests built per year in the two years following management was seven, whereas no nesting occurred in the two years before management (P = 0.002). On the basis of the number of nests built in the study site, the mean proportion of nests built each year in the managed ponds was 27%. The mean age of banded birds nesting for the first time in the managed ponds in the two years following management was 4 years, and 58% of these birds were born in the study site. These results support the hypothesis that such management actions can increase nesting opportunities in artificial habitats. These actions may provide important alternatives to birds when conditions change in previously suitable breeding grounds.

With increases in the severity and frequency of weather extremes, there is growing concern about the ecological effects of these events. However, compared to gradual climate changes, the impacts of weather extremes have been much less studied. An extreme flood struck Poyang Lake, China, a globally important wintering ground for waterbirds, in the winter of 2015-2016. The effects of the flood on waterbird richness and abundance at Poyang Lake was assessed by comparing waterbird survey data at nine sub-lakes before (2014-2015), during (2015-2016) and after (2016-2017 and 2017-2018) the winter flood. Flooding greatly influenced waterbird abundance, with the abundance of all birds and each bird group declining by 19.7-75.5% during the flood winter relative to their values during the previous winter. Total waterbird abundance increased rapidly to pre-flood levels 1 year after the flood, suggesting that flooding mainly influenced waterbird distributions by causing waterbirds to escape to adjacent refugia. The negative impacts of extreme flooding shown here indicate that caution should be exercised in planning for a dam at the outlet of Poyang Lake. The proposed dam might have the potential to create the extreme high water levels that are unsuitable for many waterbirds.

Effectiveness of rehabilitating wildlife following oil spills has been controversial. Impacts include mortality or changes in behavior affecting health or reproduction. Immediately following a bunker fuel oil spill on San Francisco Bay, California, USA, a unique experiment was conducted to examine the movement and foraging behavior of Surf Scoters (Melanitta perspicillata) that had been oiled, captured, cleaned, rehabilitated, and radio-marked. Unoiled Surf Scoters were similarly cleaned, rehabilitated, and radio-marked while other unoiled Surf Scoters were radio-marked as controls. Surf Scoters in the control group had larger home-ranges (46.29 ± 3.23 km²) than either the oiled/rehabilitated (32.58 ± 5.48 km²) or rehabilitated only groups (31.06 ± 3.05 km²); the control group also was more likely to use unsheltered, shallow areas of the bay (66.9 ± 4.3% of locations) than either the oiled/rehabilitated (50.3 ± 5.2%) or rehabilitated only groups (58.2 ± 6.5%). The oiled/rehabilitated group was closer to shore (986 ± 149 m) than rehabilitated (1,894 ± 295 m) or control groups (2,113 ± 227 m). Differences in habitat use, movement patterns, and home range sizes indicated that Surf Scoters held in captivity were more restricted in their movements; therefore, captivity and rehabilitation practices may also influence success of the rehabilitation.

The roosting ecology of most waterbird species is poorly known and even less is known from southern Asia, where many species inhabit human-modified areas. Roosting ecology of the Black-headed Ibis (Threskiornis melanocephalus) was studied in urban and rural settings in southern Rajasthan, India. Analyses focused on assessing whether site characteristics varied between nest sites, urban and rural roost sites, and paired sites (i.e., a waterbird roost site near Black-headed Ibis roosts but without Black-headed Ibis). Additionally, the hypothesis that factors affecting Black-headed Ibis numbers at roosts would be similar at urban and rural sites was tested. Tree characteristics (canopy cover, girth at breast height) were different (P < 0.05) between nest and roost sites. Urban roost sites experienced 2.3 times greater disturbance than rural roost sites. Paired site characteristics were similar to urban roost sites (multi response permutation procedure, significance of δ = 0.3), but were dissimilar to rural roost sites. Co-occurring roosting bird assemblages were significantly different between roosts and paired sites (significance of δ < 0.01) in urban and rural settings. Black-headed Ibis numbers at urban roosts were influenced by multiple variables, but models showed considerable ambiguity at rural sites. Results strongly suggest that including roost sites in a species status assessment is important.

Limited information about nutrition exists on American White Pelicans (Pelecanus erythrorhynchos) from hatching to fledging. To detail immunity, metabolism and nutrition of juvenile American White Pelicans, during 22-23 July 2011, 103 samples of regurgitate matter were collected at five Chase Lake, North Dakota, USA, and three Bitter Lake, South Dakota, USA, sub-colonies. Regurgitate sample nutrient content was significantly different for organic matter (P = 0.012), crude protein (P = 0.001), neutral detergent fiber (P = 0.014), acid detergent fiber (P = 0.005) and energy (P = 0.034) between North (n = 5) and South (n = 3) Dakota American White Pelican colonies. Average concentrations of immunoglobulins Y (2.74 ± 1.85 ng/mL) and A (9.04 ± 9.41 ng/mL) demonstrated passive transfer of immunity in regurgitate. To enhance information on growth and morphology in hand-reared American White Pelicans (n = 8), a 9-week captive trial was also conducted raising chicks from hatching to fledging. Predictive models were created to describe chick growth for intake, body weight, culmen length and tarsus length. Data collected during this study enhances both American White Pelican general ecology and conservation with implications for both captive and wild bird management.

The endangered Hawaiian Coot (Fulica alai) is one of few native waterbird species remaining in Hawaii, USA. On the island of Oahu, 56 adults were captured and sexed using a molecular method, and sexual dimorphism, seasonal variation in shield size (possibly sexually selected), and use of morphometrics to predict sex as an alternative to molecular sexing were investigated. The sex ratio was significantly male biased: 39 males, 17 females (P = 0.003). No morphometric character assessed independently differed significantly between sexes (0.056 < P < 0.975). However, a multiple regression approach indicated that tarsus length, bill height, tail length, and wing length in combination differed between sexes, but prediction of sex was nonetheless possible with only 65% accuracy. Male shield size was larger during the pre-breeding and breeding seasons than the post-breeding season, but did not vary significantly in females, the interaction between sex and season in the model being significant (P < 0.02). Within the breeding and pre-breeding seasons (a subsample of total birds), multiple regression indicated sexual dimorphism in shield width, shield length, and wing length, but prediction of sex was again only possible with 68% accuracy. Thus, neither model predicted sex sufficiently accurately for this morphometric approach to be a viable substitute for molecular sexing.

Year-round behavioral observations and surveys were used to investigate the temporal dynamics of life history events and associated variation in behavioral activities of the endangered, island-endemic Hawaiian Duck (Anas wyvilliana) on Kaua‘i, Hawai‘i, USA. Although breeding activity occurred throughout the year, backdated brood observations (n = 67) revealed that birds initiated 94% of nests during the 9-month period from September through May, their peak nesting season. A greater proportion of females (n = 149) were paired during the peak nesting season (75%) than the off-peak season (48%). Behavioral patterns (n = 984; 329 hr) differed between seasons for males but not for females. Males allocated more time to vigilance and less time to foraging during the peak nesting season than the off-peak season. Activity budgets also differed between sexes, but only during the peak nesting season. During this period, females spent more time foraging than males, whereas males allocated more time to vigilance, locomotion, and social activities. Current management objectives for the Hawaiian Duck aim to provide resources for multiple life history stages concurrently throughout the year, and although this approach is largely appropriate, our results suggest refinements in the timing of certain activities (e.g., managing nesting habitat to be available during September-May).

North American populations of Gull-billed Terns (Gelochelidon nilotica) are thought to winter in low numbers throughout Central America, with highest single-site concentrations of up to 200 individuals known from the Panama Canal zone. This paper presents information on a previously unknown stopover and wintering site in southern Honduras, where up to 1,640 individuals, approximately 20% of the entire North American metapopulation, are present during the non-breeding season. This site may be of key importance to full cycle conservation of declining North American populations. Information on habitat use in the eastern Gulf of Fonseca is also included.

Several populations of Black Skimmers (Rynchops niger), colonial waterbirds with a tactile foraging strategy, are declining. Improving our limited knowledge of Black Skimmer foraging ecology has become critical to inform conservation decisions. Black Skimmers were GPS-tracked from the Isles Dernieres Barrier Island Refuge in coastal Louisiana, USA, from 27 June-1 July 2013 and 30 May-2 June 2016, to shed light on their foraging movements during the breeding season. Black Skimmers foraged almost exclusively at night, as far as 16 km from the colony in the coastal marshes of Louisiana, in a home range of 86-256 km². Additional movement data are needed to identify areas of conservation need and provide a basis for future studies of skimmer response to environmental changes.

The breeding phenology and nest site distribution of Red-billed Tropicbirds (Phaethon aethereus) was monitored from 6 June 2014 to 18 May 2016 on Parc National des Iles de la Madeleine, Senegal. During this period, this study site was visited every 15 days to record active nests and their contents (eggs or chicks). We found up to 76 nest sites but only 49 were active in 2014-2015 and 45 in 2015-2016. Red-billed Tropicbirds bred throughout the year but numbers of active nests peaked from October to January, which may be related to the seasonality of ocean upwelling. Nests were aggregated in four areas and their distribution and occupancy may be related to the direction of the wind during the seasonal peak of reproduction from October to May. The breeding success was generally high (62.9% in 2014-2015 and 47.3% in 2015-2016) compared to other colonies breeding in less productive waters. Given the singularity and small size of this population, monitoring, management and strict protection is clearly needed to guarantee its viability.

Common Tern (Sterna hirundo) chicks are highly mobile, as they are semi-precocial. However, they generally stay in the territories near their nests until soon after fledging. In the salt marsh-breeding population in Barnegat Bay, New Jersey, USA, Common Tern chicks were recorded far from their nests before fledging. Movements from the nest were quantified at two islands in Barnegat Bay. For the first 1-3 days, chicks stayed very close to the nest. By 4 to 6 days of age, no chicks were within the nest cup, but they typically remained nearby, at a median distance of 0.45 m from the nest. From 1 to 3 weeks of age, median distance from the nest steadily increased from about 1 to 4 m. Among those chicks older than 3 weeks, the median distance away from the nest was 6.45 m, and none were found closer than 1.75 m. Common Tern chicks older than one week were usually not present in their territories, despite continuing to rely on their parents for care. The contrast between this and previous studies of the Common Tern may relate to habitat differences.

Intra-seasonal changes in depredation influence nest survival, but this may be mediated by the foraging behavior of predators or seasonal variability in habitat features. Intra-seasonal differences in factors influencing daily nest survival rates of Black Terns (Chlidonias niger) were studied in southern Ontario, Canada, during May-August 2015 and 2016. Survival of early and late-nesting individuals in relation to nest-specific temporal and spatial characteristics was investigated, including nest habitat change over the nesting cycle. The daily nest survival rate for early nesters (n = 112) declined with increasing nest age (β = -14.97; P = < 0.001), and rose with increased proportion of vegetation (β = 0.01; P = 0.02) and increased conspecific nest spacing (β = 0.01; P = 0.04). Daily nest survival rate for late nesters (n = 80) was influenced by increasing nest age (β = -12.99; P = < 0.001), with a decline during the nestling stage, and no habitat or spatial correlates. A propensity toward smaller clutch sizes with diminished survival in the late season (β = 0.67; P = 0.01) further highlights intra-seasonal differences in factors that affect survival. Predator foraging behavior may influence intra-seasonal survival patterns more than seasonal variability in habitat features.