Pollution caused by anthropogenic debris is a concern for marine biodiversity conservation due to its impact on biota. Debris in seabird nests has been largely unreported in regions like southern South America. Here, novel information is presented regarding the incorporation of marine debris into the nests of Imperial Cormorant (Leucocarbo atriceps) inhabiting the Beagle Channel, Argentina, along an anthropogenic gradient using a photographic method. In doing so, the incorporation of debris was compared under two different scenarios of anthropogenic activities due to the COVID-19 lockdown. The furthest colony away from the city of Ushuaia had no debris at all, while the colony located close to it had a high impact of anthropogenic debris, most of which was plastic. During the lockdown, the colony close to Ushuaia showed a significantly lower proportion of nests (41%) with debris when compared to the following season, with no lockdown (90%). Even more, the amount of anthropogenic debris items per nest increased significantly during the season with no lockdown. Also, the main type of debris varied between seasons, being plastic ropes more dominant during the first season (26%) and plastic bags during the second season (57%). Our study shows that changes in consumer' habits can have a positive impact on seabirds exposed to plastic pollution. Since such changes are possible, we suggest implementing awareness campaigns and seek to establish legal frameworks along with equitable interventions in order to reduce plastic pollution on seabirds' colonies.

Limited information exists on Little Gulls (Hydrocoloeus minutus) in the Hudson Bay Lowlands, their presumed primary North American breeding site. A 48-year checklist dataset from 1973–2021 in the Ontario portion of the Lowlands combined with a 10-year intensive observation dataset from July to September 2009–2019 in southwestern James Bay, Ontario, reveal key insights. Checklist records consisted primarily of migrants and included 473 Little Gulls (annual mean = 14.8, range = 0–91), with peak numbers (122 individuals) in the third week of May. Intensive observations documented 267 Little Gulls (range = 3–54/year). In the intensive study, adults were first recorded in the third week of July, while second-year birds and juveniles appeared in the first week of August, when all age groups peaked in abundance. The last sightings were juveniles and occurred in the first week of September. This paper advances understanding of Little Gull ecology and migration in North America, emphasizing the necessity for future research. Future studies that employ advanced tracking technology will reveal breeding locations, migration routes, roosting sites, and non-breeding locations, which are vital for the conservation of this enigmatic North American gull species.

Sea ducks are considered vital indicators of ecosystem health yet are experiencing long-term abundance declines in the transboundary waters of the Salish Sea in Canada and the United States. Identifying the mechanisms driving changes in abundance or causing redistributions within this region necessitates a transboundary effort. Our analysis compiled data from both the British Columbia Coastal Waterbird Survey (BCCWS) and the Puget Sound Seabird Survey (PSSS) between 2009–2022 to assess broad-scale predator-prey interactions between Bald Eagles and priority sea ducks, using a multispecies occupancy model. Our results suggest that Bald Eagles more often than chance overlap with priority sea ducks in the Salish Sea. However, there was no evidence of second-order effects of latitude, longitude, or year on sea duck occurrence in the presence or absence of Bald Eagles, suggesting that these factors are acting independently. Our results not only help resource managers better understand the broad-scale interplay between predators and prey and the co-occurrence probability of priority sea ducks, but this analytical framework and data resource compilation also provide researchers with a foundation from which multi-species interactions and the mechanisms responsible can be disentangled across these transboundary waters.

The Eastern Black Rail (Laterallus jamaicensis jamaicensis) is a federally threatened marsh bird known for its cryptic nature, making the species difficult to study. In Louisiana, U.S.A., Eastern Black Rails have rarely been documented in the state, especially during the summer, and there have been no confirmed breeding records. This study provides the first evidence of Eastern Black Rail breeding in Louisiana. Using motion activated game cameras, we successfully recorded adults with a chick, aged 5–15 days old, on two separate occasions. In addition, unique vocalizations between adults and the chick were recorded by motion activated game cameras. Few records exist for Eastern Black Rail in Louisiana and only recently was a small year-round population documented in the southwest portion of the state. The findings of this study are critical as they further expand our knowledge on the breeding distribution of Eastern Black Rail along the Gulf of Mexico coast.

Migratory shorebirds, characterized as opportunistic species, are traversed by diverse distances in pursuit of food. A systematic review was conducted using different databases to scrutinize the diets of 41 migratory shorebirds in the Americas. The analysis encompassed 94 documents from 1919 to July 2023. Over 90% of the research relied on fecal and intestinal tract analysis, with only two studies employing molecular and DNA analysis. Prevalent prey orders included Diptera, Coleoptera, Littorinimorpha, Decapoda, and Hymenoptera, varying across five regions. While coastal areas shared similarities in prey like Mollusca, Annelida, and Decapoda, differences existed among shorebird diets, demonstrating their remarkable ability to explore various prey items during migration. Among these species, the Short-billed Dowitcher (Limnodromus griseus) and Lesser Yellowlegs (Tringa flavipes) had the highest prey count. Long-distance migratory species, particularly in the Atlantic flyway, were extensively studied in Argentina, Brazil, and the USA. Despite progress, information gaps persist, particularly in tropical regions along the midcontinental and Pacific flyways. Migratory shorebird populations are declining, facing challenges in stopover and non-breeding areas. Understanding the variability of their diets is paramount for making informed decisions in conservation efforts.

Most seabirds delay reproduction for multiple years. The standing hypothesis is that seabirds delay reproduction while they develop foraging skills. Here, I clarify an old but understudied alternative hypothesis: young seabirds also undergo a phase of social development before beginning reproduction. I then provide a prefatory, but necessary, test of this hypothesis with American Herring Gulls (Larus argentatus smithsonianus), asking whether young gulls have an opportunity for social development at colonies before breeding. A corresponding set of predictions is that young gulls are (A) present at breeding colonies, (B) socially engaged, and (C) not breeding. I conducted census counts and behavioral observations at a northwest Atlantic breeding colony on Kent Island, New Brunswick, Canada during summers 2022–3, along with supplementary observations at Great Duck Island, Maine, USA. Immature gulls in an advanced predefinitive plumage stage were common (2.5–6.2% of a total census of ∼4,000 birds). Younger birds, identified via less-advanced predefinitive plumage stages, were nearly absent (generally <1% of census). Immature birds were socially engaged around foreign territories. Yet only 1–4 immature birds held territories or nests of their own. This phenomenon suggests the social conditions at breeding colonies may set the stage for forms of social development that, in turn, set the stage for life history and plumage evolution.

We provide information on new records of the Cattle Egret (Bubulcus ibis) in the Drake Passage area and within the Argentine Islands (Wilhelm Archipelago, Antarctica). Included are notes on the peculiar behavior of and difficulties experienced by this bird in the extreme conditions of the Antarctic.

The White Ibis, Eudocimus albus, primarily consumes aquatic crustaceans and insects but exhibits an opportunistic diet that includes a diverse array of prey. During a water quality survey in Costa Rica, a small flock of White Ibis was observed foraging along a river, where they were notably seen consuming tadpoles of the Cane Toad, Rhinella horribilis. These small black tadpoles exhibit highly social behavior, often forming large schools in breeding site shallows. This observation marks the first documented instance of White Ibis consuming tadpoles of a toxic species, with no adverse reactions noted during several minutes of feeding in areas abundant with tadpoles. The absence of tadpoles from White Ibis diets suggests potential factors such as the availability of more attractive food sources or biases in collection methods, including the rapid digestion of soft-bodied animals like tadpoles. Additionally, White Ibis tend to consume free-swimming organisms where they occur in high densities, contributing significantly to their diet in such areas. Further investigation into the importance of tadpoles in the White Ibis diet at our study site could provide valuable insights into their foraging behavior and dietary preferences.

The Great Blue Heron (Ardea herodias) is an indicator of aquatic ecosystems. Understanding its population trends is vital for gauging ecosystem health. However, trends vary in North America, posing challenges to effective conservation strategies. This study examines the 25-year population trends of Great Blue Herons in Quebec through aerial surveys. Generalized linear models were employed to track nest and heronry abundance, considering bird conservation region (BCR), survey effort, and years. A model selection approach identified the best predictors. The best model for nest abundance, incorporating additive effects of BCR and year, explained 87% of the model selection's weight, revealing a decline across all BCRs from 1992 to 2017. For heronry abundance, two models highlighted the influence of BCR over the years, indicating relative stability in the province. Divergent trends between nest and heronry abundance raise questions about influencing factors. Proposed strategic conservation actions aim to ensure that the most ecologically valuable heronries are properly preserved. This may involve reassessing protection measures and, in some cases, considering restoration actions. This study underscores the challenge of adequately covering large administrative regions, with proposed resolutions including a dual-frame design for future surveys.

Recreational disturbance is one of the major threats faced by shorebirds in the Western Hemisphere, especially during the non-breeding season. Between July 2016 and April 2017, shorebird surveys and behavioral observations were conducted at Bahía de Todos Santos, Baja California, Mexico. These data and generalized linear mixed models were used to assess whether (1) increased potential human disturbance resulted in lower shorebird abundance and (2) behavioral responses of shorebirds varied depending on the agent of disturbance (stimuli from human activities, e.g., people) and group size (e.g., number of people in the group). Shorebird abundance was modeled for all shorebirds combined and for three categories of body size (large, medium, small). Abundance of all, medium, and small shorebirds was negatively associated with potential human disturbance during migration periods. The probability that a shorebird would flush versus walk or become alert was modeled in response to different disturbance agents during actual disturbance events. Dogs and people had a higher probability of causing shorebirds to flush than vehicles, watercraft, and aircraft. Interestingly, the probability of shorebirds flushing decreased as the agent's group size became larger. Understanding the types of disturbance that most impact shorebirds is critical information when considering multiple potential conservation actions.