Stopover habitats in long-distance migrants such as Siberian Cranes (Leucogeranus leucogeranus) are subject to dynamic changes, both seasonally and spatially. Due to the difficulty in conserving stopover habitats across vast geographies, it is necessary to clarify the timing and route patterns of stopover sites in order to take practical measures to protect habitats. From 2014 to 2018, we successfully tracked n = 10 Siberian Cranes by satellite tracking and obtained data for n = 26 complete migrations. We obtained the annual cycle of cranes and analyzed the repeatability between seasons and individuals. According to tracking data, Siberian Cranes started and ended autumn migration on 23 September and 19 November, respectively. Spring migration started on 8 April and ended on 4 June. The migration routes between seasons showed spatial similarity but less repeatability. There is significant repeatability in migration routes from 48°N to 58°N (Russian areas) between individuals in spring. Our results provide support for some seasonal plasticity in the timing of migration and flexibility in routes taken by migrating Siberian Cranes. Other than rigid patrol and guardianship for the entire spring, we also propose strengthening monitoring and protection in the identified stopover areas from the end of March to the beginning of May each year.

Understanding important factors for breeding Eared Grebes (Podiceps nigricollis) is essential for its conservation. We aimed to study the impact of some factors on nests and breeding success in this species in fishponds (S Poland). Number of Eared Grebe nests were counted on particular carp ponds. Pond size, vegetation cover, number of nests in colonies of associated gull or tern species, and age of stocked common carp (Cyprinus carpio) were determined for all ponds with nests. We also investigated the relationship between nest size, material used to construct them and clutch size. Number of Eared Grebe nests positively correlated with number of breeding pairs of associated colonial species (terns or gulls). Selection of the breeding site by the Eared Grebe can be explained by appropriate nest protection by large colonies of associated species (Whiskered Tern Chlidonias hybrida and Black-headed Gull Chroicocephalus ridibundus). Nest size was not related to clutch size. A negative relationship between breeding success and number of nests of Eared Grebe was found. Food is a not limiting factor for the Eared Grebe on fishponds with extensive production, and presumably other factors such as weather conditions may explain the low breeding success of this species.

Migratory wader populations are declining across all major flyways, mostly due to habitat loss and human disturbance. Portuguese wetlands act as key wintering and stop-over sites for many waders due to their strategic location in the East Atlantic Flyway. Despite their importance, there are major knowledge gaps in some areas, such as the Sado Estuary. The main goal of this study was to identify the phenological patterns and wintering trends of the most abundant wader species in this wetland, and to compare the results with the population trends found at regional and flyway scales. A comprehensive dataset of count data collected monthly in high-tide roosts under a set monitoring programme (2010–2019) was used. The results revealed strong declines in the overall number of waders and of three of the most abundant species—Avocet (Recurvisostra avosetta), Dunlin (Calidris alpina), and Common Ringed Plover (Charadrius hiaticula)—associated with a 21% reduction of the suitable high-tide roosts across the study area. These trends are similar to those compiled from winter counts for the entire Sado Estuary, and at regional (Tagus Estuary) and flyway levels. Our results highlight the need to maintain suitable high-tide roosts to contribute towards reverting current declines in wader populations.

Migratory behavior of California Great Egrets (Ardea alba) is poorly understood. GPS tags were deployed on eleven Great Egrets on Tomales Bay, Marin County, California, USA. Six individuals displayed migratory behavior, four remained resident, and one individual employed both strategies across three winters. Both diurnal and nocturnal migratory movements were observed. Five of the Great Egrets flew through or wintered in the Sacramento-San Joaquin Delta and California's Central Valley, and one Great Egret moved through Nevada, Arizona, and Mexico, indicating use of wintering grounds outside of California. This study provides the first documentation of partial migration by Great Egrets, and the first information on round trip migration of this species on the U.S. west coast. Our results further illustrate the importance of connectivity between coastal and inland habitats for migratory birds.

Environmental DNA is a burgeoning tool used to address wide-ranging scientific questions, including determining diets of difficult-to-sample predators. Loons are large piscivorous diving birds that capture and consume prey underwater, making it nearly impossible to visually determine their diet via observation alone. Identifying species' diets is important for understanding basic life history traits, and revealing key prey species can clarify species' roles in complex trophic webs, aid in understanding population and community dynamics, and help identify critical habitat for protection. Current information about loon diet is largely anecdotal, and traditional non-observational methods for quantifying loon diet have limitations. Analysis of eDNA from loon feces may provide biologists with a non-invasive technique for determining diet without negative sampling effects, and with increased resolution as compared to other techniques. We surveyed lakes in two areas of northern Alaska for Yellow-billed Loons (Gavia adamsii). Loon fecal samples were collected opportunistically from latrine sites without disturbing any animals and analyzed using novel marker sets to determine loon species and diet. Fish species were detected in all fecal samples, the most common being Alaska blackfish (Dallia pectoralis), and ninespine stickleback (Pungitius pungitius). This research demonstrates that eDNA metabarcoding analyses of loon fecal samples can determine the specific loon species that deposited the feces and characterize the piscine portion of their diet with limited disturbance to the animals.

Millions of wetland-dependent birds annually depend on saline lakes and associated wetlands in the western United States. Understanding the population status and trends of birds with different life histories and habitats can guide efforts to secure water resources needed to sustain bird habitats. We used a 21-year dataset to examine population trends for 24 survey units for migratory shorebirds, waterfowl, and other waterbirds at Great Salt Lake and associated wetlands. We found stable or positive trends for 36 of 37 species or groups in fall, spring, or both seasons when considering survey units in aggregate. Stable, positive, and negative trends were observed in individual survey units. Foraging technique, migration distance, and taxonomic groupings were unrelated to trend direction. Research is needed to test whether survey units represent high-quality habitat. With declining regional water resources, stable and positive aggregate trends reinforce the importance of surveyed units at Great Salt Lake and associated wetlands to wetland-dependent birds. Ensuring continuation of stable and positive trends will require identifying environmental factors—including water quantity and quality—driving trends, and require coordinated regional management and monitoring of wetland-dependent birds.

Determining embryo age is important for predicting hatch dates, planning nest visitation schedules, and as a model covariate examining factors affecting nest survival and behavior. Two common methods of estimating embryo age are egg candling and egg flotation (floating). Despite the reliance on these methods, there is little information regarding the repeatability of these techniques between multiple observers, or whether these techniques produce equivalent estimates. To determine how these methods compare and if precision of each method is biased by individual observers, paired observers candled and floated the same Common Eider (Somateria mollissima) eggs. We compared differences in embryo-age estimates across incubation between (1) candling and floating, (2) paired observers candling eggs, and (3) paired observers floating eggs. Floating and candling produced different embryo-age estimates during some periods of incubation. Although most estimates deviated by a few days, inconsistencies could impact results and statistical power when methods are interchanged between projects or across years. Observers derived different embryo-age estimates for candling, but not for floating, suggesting flotation may be more reliable. Our results suggest caution when combining candling and floating-derived data when collected across incubation stages. Investigators should consider how data collected by multiple observers may affect their research question.

Population estimates derived from monitoring efforts can be sensitive to the survey method selected, potentially leading to biased estimates and low precision relative to true population size. While small unmanned aerial systems (UAS) present a unique opportunity to survey avian populations while limiting disturbance, relatively little is known about how this method compares with more traditional approaches. In this study we compared population estimates of Snowy (Egretta thula) and Cattle Egrets (Bubulcus ibis) in a mixed-species colony in the Chesapeake Bay (Maryland, USA) derived from UAS photo counts, flush counts, flight-line surveys, and in-colony nest counts along with the time required to derive an estimate via each approach. We found that UAS counts and flush counts produced lower pair estimates than nest counts and flight-line surveys (P < 0.05), and required dramatically less time (x̄ = 6, 8, 84 and 90 min, respectively). These results suggest that while UAS have the potential to collect valuable survey data from breeding colonies that are hard to reach or are especially sensitive to the disturbance inherent in other methods, inherent biases should be considered and caution should be used when comparing results between survey types.

Senegal hosts hundreds of wintering Eurasian Spoonbills Platalea leucorodia every year. To contribute to the paucity of knowledge on their distribution and ecology, this study aimed to compare the occurrence and behaviour of spoonbills at the three most important sites in Senegal: Djoudj National Park, Technopôle of Dakar and Palmarin Reserve. Based on monthly counts in 2017 and 2018, Djoudj reached peak numbers of more than 2500 birds in April. The number in Palmarin peaked at 500 birds in October. In both cases this well exceeds the 1% threshold for the East Atlantic Flyway population, but Djoudj can hold up to a sixth of the population. Technopôle is an intermediate site that rarely hosts more than 50 individuals. Based on the scanning of behaviours throughout the day, we show that foraging activity was high early in the morning and decreased towards noon. At Palmarin, Spoonbills spent more time resting (68%) than at Djoudj (50%), allocating less time to foraging (16%) compared with Djoudj (29%). If this indicates favourable wintering habitat at Palmarin, the growing population of Eurasian Spoonbills from Europe may increasingly rely on the Palmarin site during the coming decade.

A presumptive natural West Nile virus outbreak occurred in 23 of 27 captive American White Pelicans (Pelecanus erythrorhynchos) located in Starkville, Mississippi. Twenty-one birds were confirmed positive through either reverse transcriptase PCR, immunohistochemistry (IHC) or complement fixation serological testing. Two additional birds were presumed positive by histological changes typically ascribed to West Nile virus. Two of the 23 infected pelicans had been previously implanted with a temperature monitor and served as case studies. These birds began showing clinical signs in July on day 27 and 30 post-placement, preceded by a reduction in food intake one day prior in both cases. Initial clinical signs observed in both birds included wing droop and lethargy and within 72 hours both birds displayed increased agitation and aggression during feeding. Here we detail the progression of disease caused by West Nile virus in two cases.

Heron vocalization and its behavioral functions are one of the least researched aspects of heron biology. The main aim of this study was to investigate the patterns of seasonal and daily vocal output of male Little Bittern (Ixobrychus m. minutus; n = 8) during the breeding season (May–August). The advertising call started on 10^th May, and finished on 28^th July. The first peak of calling activity occurred between 21^st May and 1^st June, and the second one was between 14^th June and 7^th July. The daily vocal activity fluctuated and depended on the time of day. The males were most active between 0300–0900 hours and 1600–2200 hours, with the highest peaks in vocal output occurring before sunrise and before sunset. Higher vocal activity was observed in the evening compared to the morning hours. Moreover, the vocal activity of males was not related to air temperature.

We review the distribution of White-cheeked Pintail (Anas bahamensis rubrirostris) in mainland Ecuador and show that the species has expanded its range significantly. Contrary to published records, A. b. rubrirostris has been present in mainland Ecuador at least since the early 20^th century, although probably in low numbers. During the 20th century, the species increased its range along the entire coastlands of Ecuador and has reached the coasts of Colombia. The species has also extended its presence along the Andes, and we report the first breeding records of A. b. rubrirostris in the Andes at altitudes between 2360–2440 m, the highest across the entire range of the species. Additionally, we describe the transitioning plumage between ducklings and juveniles, which has not been portrayed in detail before.