Anthropogenic islands have become important alternative nesting sites for wading birds by providing habitat where natural sites are degraded or absent. However, anthropogenic islands have higher elevations and experience more disturbance than natural sites, which may alter nest predation risk. Yet, little is known about the degree to which wading bird productivity varies between colony types. We used a generalized linear model approach to determine the effect of colony type and resource availability on the species-specific productivity of wading birds at Lake Okeechobee from 2010 to 2019. Great Egret (Ardea alba) productivity did not vary by colony type, whereas Snowy Egret (Egretta thula) and Tricolored Heron (Egretta tricolor) on average produced 0.2 and 0.7 more chicks per hatched nest at natural marsh island colony-sites (n = 6) than at anthropogenic island colony-sites (n = 4), respectively. This suggests that anthropogenic island colony-sites provide lower quality nesting habitat for these species than do marsh colony-sites. However, anthropogenic islands provide nesting habitat in years when marsh colony-sites are limited, and thus increase long-term productivity. Constraints on the ability of anthropogenic islands to support wading bird nesting can be relaxed by optimizing island location and structure during their creation.

Many shorebirds rely on a set of key sites to complete their annual cycles at the flyway, regional, and landscape scales. Coastal wetlands on Chiloé Island, Chile, (Chiloé) support a high proportion of the Hudsonian Godwits (Limosa haemastica) spending the boreal winter along the Pacific coast of the Americas. We conducted annual counts of godwits on Chiloé between 2010 and 2020 to estimate trend in the population. To understand use of individual sites and local networks of sites (clusters), we conducted monthly counts September 2013–March 2014 and September 2017–March 2018. Because of wide variation in annual counts, we did not detect a significant trend in abundance of godwits on Chiloé. Mean monthly abundance summed across all sites during December–February varied markedly among site clusters, with godwits being most abundant in the central Chiloé cluster. Across Chiloé, variation in monthly counts of godwits at individual sites was twice as great as variation in counts summed within a cluster. Casual re-sightings of color-flagged godwits supported the idea that godwits used clusters consistently across years. Our results illustrate the importance of conserving a network of sites across multiple scales as an important step in maintaining Hudsonian Godwit populations.

A holistic approach to monitoring reproductive success of birds includes determining numbers of pairs, nests, chicks, and fledglings. Long-term monitoring will elucidate potential changes in the breeding population size and distribution, and possibly the causes of those changes. Further, monitoring in all stages of the reproductive cycle will help identify which stage might be limiting population growth. To assess the historical breeding populations of coastal birds in Alabama, we conducted a literature review and summarized data on reproductive metrics for American Oystercatcher (Haematopus palliatus), Black Skimmer (Rynchops niger), Least Tern (Sternula antillarum), Reddish Egret (Egretta rufescens), Snowy Plover (Charadrius nivosus), and Wilson's Plover (Charadrius wilsonia). We found 287 records from 20 sources with various metrics reported, including number of adults, pairs, nests, chicks, and fledglings, and 92 eBird records. We compared historical records to data collected during 2018–2021 to determine if and how breeding populations changed. We also compared historical and recent nesting distribution along the Alabama coast. We discuss apparent changes in breeding population sizes and potential reasons for changes in distribution, and use recent data on breeding population size and reproductive success to assess how it relates to the current conservation status of each species in Alabama.

Impoundment of hydroelectric reservoirs deeply modifies habitats available for waterfowl because it involves transforming a fast-flowing river, its tributaries and nearby ponds and wetlands into a large body of water. Using a Before-After-Control-Impact design, we evaluated whether the creation of the Péribonka reservoir, a steep-sloped hydroelectric reservoir with low water level fluctuations, affected the abundance and species composition of waterfowl breeding pairs and broods in the area. We used helicopter-based waterfowl survey data covering a period of 2 years before and a period of 10 years after the creation of the reservoir. We also used 9 5x5 km plots and 72 km of river as control sites. Our results show that breeding pair density slightly increased after impoundment, while brood density increased significantly (sixfold), especially for Common Goldeneye (Bucephala clangula). This suggests that there were favorable habitat gains for waterfowl after impoundment, probably due to low water level fluctuations and localized areas of shallow water, and that mitigation measures likely helped to reduce the impact of the project. Because this BACI study ended 10 years after impoundment, it remains difficult to ascertain whether conditions in the Péribonka reservoir have stabilized or are still evolving.

Understanding habitat use on a fine scale is essential for the development of management plans for threatened and endangered species. Several heavily managed State Wildlife Sanctuaries and National Wildlife Refuges provide critical foraging habitat for the endangered Hawaiian Stilt, or Ae'o (Himantopus mexicanus knudseni). The foraging behavior and habitat use of Hawaiian Stilts at Hāmākua Marsh State Wildlife Sanctuary, O'ahu, Hawai'i was investigated. Foraging tactics, success, and microhabitat were recorded for 227 birds over 24 2-hr periods from September to December 2021. Hawaiian Stilts made the most foraging attempts in shallow (< 8 cm deep) water, and had the most success in intermediate (8–15 cm deep) water. The most commonly recorded foraging tactic was pecking, while the most successful was plunging. Visual tactics were both more common and more successful than tactile. The overall foraging success rate for Hawaiian Stilts in this study was 0.16, markedly less than success rates observed by other researchers in related species. It is possible that prey in Hāmākua Marsh is either less abundant or less vulnerable to capture than in other similar habitats. Our results suggest that future habitat management for Hawaiian Stilts should prioritize areas of shallow water and further investigate food availability.

Wetlands in arid and semiarid regions are recognized as priority ecosystems for conservation of wetland-dependent species in these systems. Evaluation of habitat selection is necessary for effective habitat management and, consequently, population management. The Lower Colorado River Valley population of Greater Sandhill Cranes (Antigone canadensis tabida), winters exclusively in portions of southwestern Arizona and southeastern California. Therefore, there is a need for information pertaining to winter habitat selection to guide management decisions. We attached solar-powered satellite platform transmitter terminals to greater Sandhill Cranes and used daily global positioning system locations. Each used location paired with 10 randomly generated locations had equal probability of drawing any of the randomly generated locations. We evaluated habitat selection and found the model that included land use type (β = –5.85, SE = 0.23, P < 0.001) and distance to roost (β = –4.61, SE = 0.16, P < 0.001) as interactive effects was the most supported model in the candidate set. Our results emphasize the importance of maintaining wetlands in close proximity (∼ 5 km) to selected land use types, which can be challenging to manage for in arid systems but are particularly necessary for this high conservation priority population of greater Sandhill Cranes.

Gravel rooftops are important for nesting Least Terns (Sternula antillarum) in Florida. A network of partners from the Florida Shorebird Alliance (FSA partners) monitor roof-nesting Least Terns by conducting street surveys - a count of flying adults seen from the ground. We used double sampling to adjust street survey data and produce a population estimate for the 2018 nesting season (1 May–20 June). In 2018, FSA partners conducted street surveys at 96% (n = 138) of the active rooftop colonies in the state. In a random subsample (n = 62), we conducted direct counts of breeding adults and produced a detection ratio of 0.61, a ratio estimate of 59.28 ± 5.01 breeding adults/rooftop, and an adjusted population estimate of 8,180 ± 692 breeding adults (95% CI: 6,825–9,536). Cross-validation tests using data collected before and after the 2018 study produced accurate and unbiased population estimates derived from the detection ratio and street surveys. We used available street survey data from 2015 to 2020 and found a 7% population increase. We suggest validating the detection ratio every three years to develop accurate abundance and trend estimates of Florida's roof-nesting Least Terns.

Large scale oceanic processes can have profound consequences for marine and coastal food webs. Mortality and reproductive related impacts to seabirds have been documented for decades, and current research suggests that dietary flexibility may be a key component by which birds can mitigate environmental variation. Our motivation for this research was to better understand how a dietary generalist in the coastal environment responds to changes in prey food availability. The Gull-billed Tern Gelochelidon nilotica is a coastal nesting species that has an opportunistic generalist diet. We monitored both tern diet and density of a main prey resource to examine how responsive these terns are to annual variation in prey resources. Our results documented that the loss of a ubiquitous prey resource did not appear to influence tern annual reproductive success even though, in some years, Emerita analoga comprised greater than 70% of Gull-billed Tern diet. During breeding seasons with warmer than average sea surface temperatures, the Gull-billed Tern switched to a more terrestrial diet and focused aquatic foraging activities upon crustacean species that are more tolerant of warmer water temperatures. Dietary plasticity can be beneficial to mitigate variation in prey resource availability and impacts on reproductive success, and the ability to respond rapidly to changes in resources may play an important role in how coastal species can acclimate or adapt to annual changes in the prey base.

Colonial nesting in seabirds is advantageous for protection from predators—spotting a predator, mobbing, and predator swamping. Familiarity with nesting areas gives knowledge of protected sites and may promote site fidelity. Familiarity with nearest neighbors helps nesting success by lessening intraspecific aggression and increasing social facilitation, and may promote group adherence. Group adherence has been proposed as more important than site tenacity for some species where nesting areas are frequently disturbed. Ground-nesting terns often nest at disturbed sites, and their colonies are accessible to predators. Serendipitously, I was able to test the concept of group adherence in individually color-marked California Least Terns Sternula antillarum browni during early egg-laying when some nests in a colony in southern California were depredated, and the adults deserted. A week later, I found the majority of those birds nesting at the edge of a small Least Tern colony 28 km distant, where they laid a second clutch and remained at the site the rest of the breeding season. The following breeding season, no color-marked terns nested again at the small colony where they had moved after disturbance.

Millions of migratory waterfowl winter in the coastal wetlands in Shanghai City, among which Eastern Spot-billed Ducks and Mallards are among the most common species and are sensitive to infection with avian influenza virus. However, information on the migration behaviors of these two species in Northeast Asia is lacking. Therefore, GPS transmitters were used to track the migration of 13 Eastern Spot-billed Ducks and eight Mallards wintering in Shanghai during 2017–2020. Mallards covered a (mean ± standard deviation) migration distance of 1,663.69 ± 1,063.33 km, with wider variation than Eastern Spot-billed Ducks (1,639.24 ± 642.72 km), though the difference was not significant. Both species ended their northward migrations in Northeast Asia encircling the Yellow Sea, mainly in northeastern China. The dynamic Brownian bridge movement model confirmed that multiple stopover sites mainly located in the Korean Peninsula along the Yellow Sea coastline were crucial nodes for maintaining the stability and function of the migration network. This study confirmed the close relationships between habitats in the Korean Peninsula and China, indicating the importance of habitat conservation in related countries to the stability of the migration network. The results of this study additionally highlight the relationships between migration behaviors and outbreaks of avian influenza virus in Northeast Asia.

A Great Blue Heron (Ardea herodias) was observed killing a California butterfly ray (Gymnura marmorata) with a morphological abnormality off coastal California. Even though this heron species has previously been reported actively hunting batoids, this observation is the first documenting of an attack by a bird (or any other predator) on a butterfly ray. The behavior observed in this event adds butterfly rays as potential prey items of A. herodias and provides further insights on both this bird's ecology as a nearshore predator and that of ray species like G. marmorata as important prey.

Increases in population size and reductions in suitable migration stopover habitat associated with drought, water development, and agricultural practices, along with conspecific attraction, are hypothesized mechanisms for increasing flock sizes of migrating Whooping Cranes. During autumn 2021, we observed such a phenomenon during a period of drought in the central Great Plains when 46 Whooping Cranes gathered as a single flock in the central Platte River valley. We provide a detailed account of how this larger aggregation formed from 5 smaller groups, behavioral observations, and environmental conditions experienced during this event including river flow, ambient temperature, and wind and drought conditions. Here, we report considerations for environmental and hydrologic conditions preceding and during this event as well as use patterns and behaviors we observed while the largest single flock of Whooping Cranes ever documented in the United States portion of the migration corridor was in the central Platte River valley.

The White-eared Night Heron (Gorsachius magnificus) is a poorly known species. Little ecological research has been conducted on this species, and its migration route in particular is poorly understood. Clarification of the migratory routes of this species can enhance our understanding of its distribution and aid its conservation. Here, we identified the wintering and summering sites and characterized the migration route of one White-eared Night Heron by GPS/GSM tracking. Our results indicated that the Nanting River on the China–Myanmar border is the wintering site for this individual, and the Shizhuang River in Nanzhang, Hubei Province, China is the summering site. The heron migrated along the mountains and rested near rivers and reservoirs. This study is the first to reveal the migration route of the White-eared Night Heron. Our findings suggest that this species in Yunnan, Hubei, and Guizhou Provinces is not a resident bird. Generally, these data will aid the conservation of this species, including the development of action plans and the establishment of local nature reserves along its migration route and at wintering, summering, and stopover sites.

In July 2020, an individual considered to be a hybrid between a Cattle Egret (Bubulcus ibis) and a Little Egret (Egretta garzetta) was found in Hashima City, Gifu Prefecture, Japan. The first impression was that the bird was a Little Egret, but detailed observations revealed Cattle Egret characteristics in size and plumage color. The hybrid individual also had partial melanic characteristics. The present study compared the external morphological characteristics of the apparent Cattle Egret and Little Egret hybrid, using observations and measurements obtained from images. The results showed that the tarsus length, the bill length, and the observed ratio of the bill length to the bill depth at the front end of the nostril of the hybrid were intermediate between those of Cattle Egret and Little Egret. There are few accounts of inter-generic hybridization among herons and egrets in nature, with only one report from Japan. This is the first record of hybridization between a Cattle Egret and a Little Egret in nature to our knowledge.