Molt is one of the three major life events in the annual cycle of migratory birds, but has historically received less attention than breeding and migration. Research on molting and habitat use while molting is still lacking for most large bird species, especially cranes. From May to August 2018, we tracked n = 40 White-naped Crane (Antigone vipio; n = 21 adult birds during the flightless period, n = 19 juveniles born in 2018) in the wetlands along the Kherlen and Ulz Rivers in eastern Mongolia. Our field surveys found that White-naped Cranes lost their primary and secondary feathers simultaneously during molting. Using the time-series clustering method, we found the flightless period of White-naped Cranes lasted from July to August, with an average duration of 17 days. Only some individuals molted flight feathers in consecutive years. Adult females molted earlier than males, and breeding individuals molted after the eggs hatched. The molting duration of sub-adults was slightly shorter than of adults.

Improving our understanding of the effects of research activities on breeding birds is critical for proper study implementation. Effects likely vary as a function of field methods, study species, habitat, and predator community, with few larger or predictable patterns. We investigated the effects of game camera use and adult capture on the daily nest survival of 41 Snowy Plover (Charadrius nivosus) and 61 Wilson's Plover (C. wilsonia) nests in coastal Mississippi from 2018–2022. We also compared the effects of camera presence on nest survival between nests at a site with neophilic Fish Crows (Corvus ossifragus) and other sites where neophilic crows were absent. We used logistic-exposure survival analysis to estimate daily nest survival probability as a function of research activity (banding adults or placing camera at the nest), camera presence, species, and site predator community. Camera presence resulted in decreased daily survival probability (0.82 ± 0.10 SE) at the site with neophilic Fish Crows compared to daily survival probability (0.98 ± 0.001 SE) at all other nests. All other variables had non-significant effects. Our results indicate that banding and camera use at nests can be generally safe, but that researchers should test for potential negative effects of research activities in each situation, and in particular consider the local predator community.

The kleptoparasitism behaviour of frigatebirds is a fascinating example of exploitation in the animal kingdom. To date, such behaviour has never been described before in the Magnificent Frigatebird Fregata magnificens breeding population in French Guiana, one of the most important colonies in the Caribbean, which has increased exponentially in recent years, and is subject to mass mortality of chicks, most likely caused by a viral disease. I collected observations of chases and used linear models to identify the factors that contribute to the success of this foraging strategy, estimate the success rate, and the predilection of the host species. Unlike other studies, I found that the presence of adults in the chase highly increases the success rate, while other factors including the duration of the chase and the number of individuals participating to it, are not equally important. I also found a low success of the kleptoparasitism behavior as a feeding strategy independently of the chased species, corroborating previous findings.

Post-fledging parental care occurs in a wide range of colonial waterbird species but data on the behavior are limited. The behavior is hypothesized to contribute towards offspring survivorship, but opportunities for post-fledging parental care are constrained for migratory species. Two datasets were used to examine the behavior in a Great Lakes tree-nesting Double-crested Cormorant (Nannopterum auritum) colony: annual monitoring of nest success, and focal observations of successful nests. For eight nesting seasons (2012–2019) a total of 631 sample nests were tracked for nest success, fledge date, number of chicks fledged, and post-fledging adult attendance at the nest site. During the post-fledging period, 52.2% of successful nests (n = 425) had adult attendance. Fledge date was a predictor of post-fledging adult attendance (earlier nests more likely to have the behavior) but not number of chicks fledged or year of observation. Post-fledging adult attendance was estimated to average 15.9 days in length. Focal observations confirmed that fledglings visited a nest and were fed if a parent was present (10/11 times). These findings confirmed post-fledging parental care in tree-nesting Double-crested Cormorants, but late nesting birds have reduced opportunity to provision after fledging.

Geographic variation in body size has been studied in the context of Bergmann's and Allen's ecogeographic rules, which relate changes in body and appendage sizes to temperature fluctuations associated with latitude and altitude. Moreover, organisms adapted to high-altitude exhibit blunted hematological responses, promoting survival in hypoxic environments. We collected 117 adult Slate-colored Coots (Fulica ardesiaca), representing both color morphs (68 chestnut-fronted and 49 pale-fronted) and sexes (49 males and 68 females), and sampled at three latitudinal (north, central, and south) and two altitudinal (low and high altitude) levels in the Peruvian Andes. Given the absence of geographic variation in morphometric and hematological traits across color morphs and sexes, we grouped these data together. We then used linear mixed models to assess latitudinal and altitudinal variations in body size (body mass and skull length) and appendage size (relative wing chord, tarsal and culmen lengths adjusted for both body mass and skull length). The same models were applied to analyze altitudinal variation in hematological traits (hemoglobin concentration, hematocrit, and mean corpuscular hemoglobin concentration). Our findings corroborated Bergmann's and Allen's rules, showing variation in body and culmen size across elevational and latitudinal gradients. No significant differences (P < 0.05) were observed in the three hematological traits, suggesting that polycythemia is not a necessary response to hypoxia in this species. Depending on when these coots first inhabited high altitudes, our results might support the hypothesis of duration of high-altitude ancestry, suggesting that species residing at high altitudes for longer evolutionary periods might be better adapted.

Natural wetlands, which are home to many waterbirds, face an unprecedented rate of loss and degradation in Ethiopia. Nevertheless, the number of artificial wetlands associated with reservoirs that are constructed for irrigation and household water consumption purposes has increased in the past four decades. It can be argued that these reservoirs can play an important role for waterbird conservation. However, there is little information on the avian fauna of these limnetic ecosystems. The objective of this study was to assess the richness and distribution of aquatic bird species in reservoirs in Tigray National Regional State, Northern Ethiopia. Eighty-five bird species from 54 genera, 25 families, and 15 bird orders were recorded, with a mean species richness 14.23 ± 6.72 (mean ± standard deviation) per reservoir. Five of these species are near threatened, while two other species fall under critically endangered and vulnerable conservation status designations, respectively. Bird species richness was positively correlated with the surface area of reservoirs. The result provides an important insight into the ecological relationship between waterbird species richness and the limnological characteristics of reservoirs, and plays a role towards strengthening our knowledge of aquatic bird ecology and the natural history of African-Eurasian Migratory waterbirds.

Snowy Plovers (Charadrius nivosus) are a species of conservation concern in Alabama, U.S.A., where the breeding population is small and restricted to just a few sites. Despite their listing, little research has been conducted on this species in the state. Snowy Plover nests (n = 119) were monitored at Bon Secour National Wildlife Refuge during 2015–2020. Just over half (53%) of all nests successfully hatched one or more chicks. Daily survival rates of Snowy Plover nests were estimated at the refuge using several temporal and environmental covariates. Constant daily survival rate was estimated at 0.97 (SE = 0.004, 95% CI = 0.97–0.98) and the probability of a nest surviving the 32-day incubation period was 0.42 (95% CI = 0.33–0.52). The top model in the nest survival analysis included year and site. This study is important in furthering our understanding of Snowy Plover populations in Alabama and can be used as a baseline for future analyses of nest survival.

Marker Wadden is a 1000 ha artificial archipelago developed, since 2017, as a novel ecosystem to restore dynamics in a large Dutch freshwater lake with limited natural dynamics. The newly created habitats should, at flyway level, strengthen populations of threatened bird species that depend on dynamic wetlands. The archipelago includes basins with sandbars and mudflats subject to wind tides. Situated at 3 km distance from the mainland, ground predators are lacking. During the first five years of colonization (2017–2021) six pioneer breeding birds represented significant portions (>5%) of national populations. Common Terns (Sterna hirundo) and shorebirds of pioneer habitats were instantly numerous. Ducks and Black-headed Gulls (Chroicocephalus ridibundus) colonized from year two onwards and in year five gulls became the most numerous breeding birds. Staging birds such as ducks (including 13,000 Eurasian Teal [Anas crecca]), shorebirds, and spoonbills (Platalea leucorodia) appeared in internationally important numbers. We conclude that the archipelago indeed has become an important site for breeding and staging birds and at flyway level, especially in the growing season. Therefore, artificial semi-dynamic habitats with mudflats and developed at a sufficiently isolated and large scale, may mitigate losses of natural pioneer habitat in freshwaters.

North American bird populations have declined significantly since 1970 due to a variety of causes. We estimated long term changes in abundance of wintering waterbirds at Tomales Bay, Marin Co., CA, from 1992-2022. Average total waterbird numbers decreased 11.8%. The most concerning declines for taxa whose numbers in 1992 accounted for at least 5% of the combined numbers of waterbirds were for Surf Scoter (Melanitta perspicillata), Brant (Branta bernicla), Ruddy Duck (Oxyura jamaicensis), American Coot (Fulica americana), and Western (Aechmophorus occidentalis) and Clark's (Aechmophorus clarkii) Grebe. Of 29 taxa that we estimated trends for, 13 declined across our study period. Fourteen taxa had negative trends of ≥2% year^–1 for at least 10 consecutive years, meeting the IUCN's Red List criteria for Near Threatened or higher. We accounted for two influencers of primary productivity in the bay: the Northern California Multivariate Oceanic and Climatic (MOCI) index and winter freshwater inflow. MOCI was included in the best model for six taxa while freshwater inflow was informative for eight taxa. A local wetland restoration project led to increases in three of the seven species we modeled. The dynamics of waterbird numbers on Tomales Bay are linked partly to herring but other local to global factors are important.

The Southern Bald Ibis is endemic to South Africa, Lesotho, and Eswatini, occurring across high and mid- altitude mesic grasslands, and has been of conservation concern since the 1970s, resulting in a range of monitoring, research and conservation actions. We compared trends in reporting rates from the Southern African Bird Atlas Projects (SABAP), examined trends in numbers of nests reported through colony monitoring, and explored contributions made to the ‘Threatened Species Cause’ from the BirdLasser mobile app. We found the species was widely reported across the range outside of sites with known colonies and roosts, suggesting a large proportion of the population was not available for counting during the breeding season. Using insights from the SABAP data and occupancy modelling, combined with group counts from BirdLasser data, we suggest the population is likely >10,000 individuals. None of the trend analysis statistics we used revealed a decrease in population size for the period 1987 to 2021. We note that certain colonies are still being abandoned, but this is now at a lower rate (<10% of colonies). These findings suggest a stabilization in population numbers and a potential recolonization of lost range, marking a positive shift in the species’ conservation status. Our study highlights the importance and utility of integrating diverse, independent citizen science data sources in wildlife research, offering a more comprehensive understanding of species distribution and population trends, essential for effective conservation strategies.

The Sabine's Gull (Xema sabini) is a pelagic, Arctic-breeding species with a circumpolar breeding distribution. Little is known about migration routes for northern Alaska-breeding Sabine's Gulls. We tagged Sabine's Gulls on their northern Alaska breeding grounds to identify migration routes and wintering areas and compare geolocators and GPS pinpoint tags for use on small-bodied gulls. Twelve geolocators were deployed in northern Alaska in 2011 (Colville River delta) of which four were recovered, and five GPS pinpoint tags in 2021 (Qupaluk). Although the GPS pinpoint tags provided more accurate locations allowing for finer-scale habitat evaluation, and did not require recapture of birds, the overall coverage provided by geolocators was superior given constraints on the number of locations GPS pinpoint tags record. Broadly, Sabine's Gulls migrated away from the breeding grounds as expected, passing along the west coast of Alaska and south along the west coast of the Americas to winter in the Humboldt Current off the coast of Peru. Our tracked gulls used the same migratory staging and wintering areas as did Sabine's Gulls breeding in the Canadian Arctic (Davis et al. 2016). Such reliance on specific marine areas presents risks from climate-related changes or ecological damage to those areas.

The Atlantic coast of South America supports many Nearctic shorebirds during their non-breeding season where they use a network of stop-over and wintering sites. To quantify the importance of French Guiana among those sites, we surveyed and resighted banded birds in the Kourou River estuary during two periods: 1989–1997 and 2005–2008. Twenty species were recorded, among which 15 were observed every year, during migration and/or boreal wintering. The most abundant species was Semipalmated Sandpiper (Calidris pusilla), accounting for 57% of all observations. In most Nearctic shorebird species, we observed dramatic changes in numbers and phenology between both survey periods. In the 1990s, the Kourou River estuary was mainly a post-breeding stop-over site; in the common shorebird species the largest numbers were observed in September and October. In the 2000s, only few species still occurred in significant post-breeding numbers, and migration peaks occured later for some of them. Observations of 304 banded individuals of five shorebird species indicated that some staging birds stopped in southern Canada and over-wintered in Brazil or Argentina. Many of our resighted birds stopped over in Delaware Bay in spring. Our results indicate the importance of French Guiana as a fall stop-over for Nearctic shorebirds using Western Atlantic Flyway.

The American Oystercatcher (Haematopus palliatus) is a shorebird with a wide distribution along the coastal regions of the Americas. Similar to other oystercatchers, it primarily feeds on bivalve mollusks, crustaceans, polychaetes, and other invertebrates. In this study, our first aim was to describe the feeding behavior repertoire of the American Oystercatcher at the Lagoa do Peixe National Park, an important wetland for this species in southern Brazil. Initially, we compiled a repertoire of feeding behaviors from existing literature and preliminary fieldworks. Subsequently, ad libitum observations were carried out, varying in duration from 1 to 10 minutes, to quantitatively assess the species' foraging behaviors in both the oceanic beach and lagoon habitats. The behaviors were categorized into three main categories: Search, Capture, and “Mandibulation”. As a result, a total of 132 minutes of observation time and 1763 behavioral events were recorded. We observed that the Search and Capture categories had longer durations on the ocean beach, while the “Mandibulation” category was more prominent in the lagoon environment. The specific prey available in each environment influenced the choice of foraging methods, highlighting the American Oystercatcher's flexibility in adapting its feeding strategies. These findings indicate that different environments require different foraging strategies in response to varying food availability.

The North American Marsh Bird Monitoring Protocol (NAMBMP) was implemented to monitor population trends for secretive marsh birds. Single season abundance and occupancy estimates from NAMBMP data assume closed populations of resident marsh birds; however, the assumption that migrant individuals are either not present or not detected has not been tested. Furthermore, limited information is available about the effects of other environmental or biological variables on vocalization rates of secretive marsh birds. The residency status of 70 Virginia Rails (Rallus limicola) and 25 Soras (Porzana carolina) was determined based on length of stay and time of year present and differences in call-response rates and call-types between resident and migrant rails were tested. No differences between call-response rates (49.3% = residents, 44.4% = migrants, x²₁ = 0.37, P-value = 0.55) or call-types (x²₂ = 3.48, P-value = 0.18) were found between resident and migrant Virginia Rails. Sample size of resident Soras (n = 2) was insufficient to test for differences between residents and migrants and neither resident Sora responded; however, migrant Soras were found to respond during call-response surveys (34.3%). Few environmental or biological variables influenced vocalization rates in this study; however, Virginia rails were more likely to vocalize when other conspecifics vocalized (β _i = 0.76, P-value = 0.030). This research suggests NAMBMP surveys in Ohio detect both resident and migrant Virginia Rails and Soras, and thus the population closure assumption is not met. Research testing the assumption of population closure for all marsh bird species at larger geographic scales is recommended and caution should be used when estimating single season occupancy or abundance using NAMBMP data.

Double brooding is a common breeding strategy in many small species of birds but is less common in large species and has never been documented in American Oystercatchers. In the 2022 breeding season, we documented a banded pair of American Oystercatchers double brooding in West Galveston Bay, Galveston County, Texas. They fledged a chick from a nest on April 14 and a second chick from a second nest on August 10. Both chicks survived at least through mid-September, the end of our monitoring season. Double brooding in a territorial species such as American Oystercatcher could be an important breeding strategy for maintaining or increasing population numbers since nesting habitat is limited. Future studies should ensure they are considering this possibility when planning the extent of their survey season for nesting American Oystercatchers.

Mar Chiquita is an extensive saline lake associated with the Dulce River marshes, which together form a wetland of about 1,000,000 ha in central Argentina. The lake has undergone marked fluctuations in surface area and salinity in recent decades, which has produced a marked effect on waterbirds. In the last decade, surface area and salinity of Mar Chiquita have changed little. However, there have been important changes in some species of waterbirds, particularly the Chilean Flamingo (Phoenicopterus chilensis) and the Wilson's Phalarope (Phalaropus tricolor). Also remarkable has been the appearance of eight species that inhabit marine coasts in South America, in addition to other seven coastal species previously recorded. In the present decade, Mar Chiquita has dropped 1.7 m, but for the moment this change has not had a major influence on waterbirds.