The federally Threatened Eastern Black Rail (Laterallus jamaicensis jamaicensis) is difficult to detect and may not be well monitored by existing survey methods. The goals of this project were to explore occupancy and detectability of Black Rails along the Texas Gulf Coast and to determine the best months and time of day to conduct surveys. We conducted surveys at 90 points in San Bernard NWR and Brazoria NWR from 5 March through 31 May 2014. We visited each point six times—twice each at dawn, dusk, and night and used playback surveys to elicit Black Rail vocalizations. We measured habitat characteristics for each point, including the vegetation height, litter depth, water depth, stem density, canopy height, species composition, and time since last prescribed burn. Occupancy rates averaged 0.75 ± 0.25 and was greatest where the average number of stems between 0 and 10 cm in height was six or greater. The average canopy ceiling height (i.e., height of canopy ceiling above layer of dead vegetation), canopy floor height (i.e., height of canopy ceiling above soil), and number of stems between 20 and 30 cm also affected occupancy. Detection probability averaged 0.11 ± 0.03 and was highest at night, increasing over the course of the spring. Due to the low probability of detection, repeated call-broadcast surveys will be required to detect this species. The results of this study are important for determining the timing of surveys in Texas, and we suggest that future surveys for this rare species will have the greatest success if they search for birds approximately 2.5 hours after sunset.

The main reasons for the global biodiversity decline are the destruction and degradation of natural habitats caused by human activity by transforming them into agricultural lands. Although this transformation has been linked with decreased biodiversity, some bird species might have learned how to benefit from newly created habitats. We studied home ranges and habitat preferences for daytime activity and roosting of two sedentary Marsh Harriers (Circus aeruginosus) from the Evros Delta and the Mediterranean coast of the Iberian Peninsula using the results of satellite telemetry tracking. The size of the home range for the bird tagged in the Evros Delta was 158 km² (dynamic Brownian Bridge Movement Model, 95 %), while for the Iberian bird, this was more than nine times greater (1488 km²). Monthly home ranges noticeably increased during winter in Evros Delta in both years.. The birds chose habitats such as non-irrigated arable land, watercourses, inland marshes, and dump sites for daytime activity. In contrast, they avoided habitats like rice fields and complex cultivation patterns. Water-related natural habitats like inland and salt marshes were intensively used as nocturnal roosts. Despite the general negative effect of human pressure, our results showed that the species seemed to tolerate and benefit from some types of humanized environments of estuarine landscapes.

Herring Gull (Larus argentatus) populations in Pukaskwa National Park have declined by 70% over the last 40 years. Populations of avian predators that prey on Herring Gulls have increased which could be a significant factor impacting gull populations. Here, we investigate Herring Gull daytime and nighttime nest attentiveness at locations with and without evidence of nocturnal predators. In 2017, Herring Gull nest attentiveness was examined at two sites using remote cameras. At one of those sites Great Horned Owl (Bubo virginianus) predation was observed, and gull nighttime nest attentiveness was lower there than at the site where owls were not observed. There were no inter-site differences in daytime nest attentiveness. In 2018, Herring Gull nest attentiveness was further investigated at the site where owls were present. At that site, Herring Gull nighttime nest attentiveness was significantly lower than during the day. Extended periods of absence of gulls from their nests during the night corresponded with the presence of owls. Predation of nest contents, in addition to the effects of other environmental stressors, are likely contributing to declines in Pukaskwa National Park's Herring Gull population.

Thick-billed Murres (Uria lomvia) are among the most numerous and well-studied seabirds in Canada; yet, there is a considerable lack of information concerning the population status of remote Canadian Arctic colonies. The only known colony of Thick-billed Murres in the western Canadian Arctic is located at the coastal cliffs of Cape Parry Migratory Bird Sanctuary, Northwest Territories. Historical estimates at this site range from 125–800 murres between 1953–1980, however, recent population data is lacking. We conducted boat-based photo census surveys between 2002–2021 to provide updated counts of murres at Cape Parry. The number of Thick-billed Murres observed at Cape Parry during our study period ranged from 570 birds in 2002 to 1,358 birds in 2019. Counts suggest the colony at Cape Parry increased considerably since establishment of the Migratory Bird Sanctuary in 1961, with less pronounced growth over the period of our study (2002–2021). As climate change and human activities rapidly transform the Arctic, monitoring and conservation of potentially vulnerable populations, such as the Cape Parry murre colony, will be increasingly important to maintain ecological integrity of marine ecosystems.

Black Skimmers (Rynchops niger) are sexually monochromatic seabirds that are dimorphic in size. Although most dimorphic seabird adults can be accurately sexed using non-invasive techniques, determining the sex of pre-fledglings is more challenging. Schew and Collins (1990) developed an equation to estimate chick age from wing chord and used body mass of chicks ≥ 24 days old to evaluate the sex of skimmers in California; however, this was not verified on known-sexed individuals. Our objective was to assess the accuracy of their methodology on banded skimmer chicks from southwest Florida whose sexes were confirmed during adulthood. Out of 32 skimmers, Schew and Collins' (1990) method only classified 44% of males and 81% of females correctly. While males on average were larger than females, there was considerable overlap between the sexes when measurements of body mass, culmen and tarsus length were plotted against wing chord. It appears our Florida chicks grow slower than those in the California study and do not asymptote until after they are flight capable. As Black Skimmer populations decline, further research is needed to determine the most effective chick sexing method as knowledge of survival rates of pre-fledglings by sex will be critical for evaluating management efforts.

Chickaloon Flats, Kenai National Wildlife Refuge, is an 11,000-ha tidal mudflat complex in upper Cook Inlet, Alaska. One-third (23 of 70) of Alaskan shorebird species use this protected coastal estuary stopover during migration. We conducted an isotopic approach to estimate probable breeding, staging and/or non-breeding origins of six shorebird species, some of high conservation concern, using Chickaloon during spring and fall migration of 2009 and 2010. We analyzed stable-hydrogen (δ²H), carbon (δ¹³C), and nitrogen (δ¹⁵N) isotope ratios from feathers and performed a likelihood-based assignment to infer North and South American origins. Estimated molting distributions for Greater Yellowlegs (Tringa melanoleuca) occurred in southwest Alaska, and south-central Alaska for Short-billed Dowitcher (Limnodromus griseus caurinus). Lesser Yellowlegs (Tringa flavipes) likely molted in western Alaska and a latitudinal band across Canada and wintered throughout the contiguous United States. Least Sandpipers (Calidris minutilla) wintered from Oregon and south in North America but showed an isotopically similar possibility in Ecuador, Colombia, and Venezuela. Long-billed Dowitchers (Limnodromus scolopaceus) molted primaries across western United States and Canada. Pectoral Sandpipers (Calidris melanotos) likely molted near Rio de La Plata in southeastern South America. These results highlight the overall value of Chickaloon Flats as a stopover for long-distance shorebird migrants.

In 2012, 11 small islands were created by the deposition of sediment from dredging operations in connection with the creation of navigation channels, along the main canal of Bahía Tóbari, Sonora, Mexico. During the breeding seasons of 2017–2019 and 2021–2022, we conducted repeated boat surveys each season, and documented 12 species of birds breeding on these islands, including eight species of colonial waterbirds, three shorebirds, and one owl. The number of breeding species varied between 7 (2017) and 11 (2019), and the number of breeding pairs varied between 1,686 (2017) and 17,970 (2018). From 2017 to 2018, there was a ten-fold increase in the total number of pairs (from 1,686 to 17,970), then it decreased to 8,482 pairs by 2022. Royal Tern (94 fold) and Elegant Tern (31 fold) were the species whose numbers increased the most from one year to the next. Six of these species are federally listed in Mexico, and five of them were not previously recorded as breeders in the bay. The number of pairs of Elegant Tern, Black Skimmer, and American Oystercatcher are 10%, 15%, and 7% of their biogeographic population, respectively, and therefore this site qualifies as an Important Bird and Biodiversity Area.

We evaluated diet and diet assessment methods for the California Least Tern (Sternula antillarum browni) at two nesting sites in California over 12 years (2001–2012). California Least Tern diets at Alameda Point (37° 47′ 14″ N, 122° 19′ 12″ W), an estuarine site, and Purisima Point (34° 46′ 39″ N, 120° 37′ 35″ W), an open coast site, were compared using dropped fish and hard parts (otoliths and scales) from regurgitated pellets and fecal samples. SIMPER analyses, Kendall's tau, Kruskal-Wallis, Dunn's test, rank-sum tests, and Welch's t-test determined any differences in assessment methods, chick and adult diets, and sizes of prey items. Diet composition differed between sites for both dropped fish (25% similar) and fecal samples (26%). Assessment methods showed similar results at Alameda Point (79%) for dropped fish and fecal samples but not at Purisima Point when comparing dropped fish to fecal samples (12%) and fecal samples to regurgitated pellets (19%). There was no difference in diet composition at either site or between any method using adult-only samples. All differences in diet composition appeared during the rearing/fledging stage. Fish species dropped at both sites were deeper-bodied (17 mm) than those consumed (11.9 mm), with terns at Purisima Point dropping deep-bodied species typically not consumed and those at Alameda Point dropping larger individuals of usually-consumed species. When comparing adult and chick diets at Alameda Point using fecal samples, composition was similar, and chicks ate larger prey. Our results suggest that more than one assessment method is necessary to provide a complete dietary picture.

Biometrics have been widely employed to predict sex when clear dimorphism is lacking. In this study, we aimed to assess sexual dimorphism in the Mediterranean Shag (Phalacrocorax aristotelis desmarestii) and provide predictive functions for sex determination based on biometrics. A total of 102 individuals were employed, with 62 individuals used for model construction and 40 for effectiveness testing. Sex determination was accomplished through feather samples via CHD gene amplification for live birds and gonadal inspection for deceased birds. Eleven measurements were taken and analysed: bill depth, bill width, culmen length, bill length to feathers of side, wing length, 3rd primary length, tarsus length, tarsus depth, tarsus width, tail length, and body mass. We employed Generalized Linear Models (GLM) to construct the predictive equations. Sexual dimorphism was evident, with males displaying significantly larger bill depth, tarsus length, and wing length than females. The developed models, based on these variables, achieved accuracies ranging from 89.29% to 97.62% in sexing the birds. Determining the sex of birds enhances insights into behavioural and population dynamics of this vulnerable subspecies.

I describe seasonal changes in the distribution of Least Terns (Sternula antillarum) along the Atlantic and Caribbean coasts based on banding recoveries and data submitted to eBird and WikiAves. Human disturbance of nesting sites and habitat loss has caused declines in most populations, necessitating focused conservation activities. Yet little is known about where these birds occur away from their breeding colonies, or what survival threats they may face. Limited observations during the non-breeding season in the Caribbean and along the Atlantic coasts of Central and South America are typically assumed to be individuals from breeding colonies along the east and Gulf coasts of the U.S. and along the Missouri and Mississippi rivers and their tributaries. However, existence of nesting sites throughout the Caribbean, along the Atlantic coast of Central America, and along the north coast of South America indicate a more complicated distributional picture. Most of the limited band recoveries obtained south of the U.S. are of birds killed during hunting activities. Future research attention, especially including banding at South American, Central American, and Caribbean nesting sites, and efforts during October–April to locate and identify marked birds, is necessary to develop a full life cycle conservation strategy for this species.

Migration is an important part of the life history of avians. Understanding the migration routes of birds is of great significance to unravel the migration strategies and mechanisms of birds and helps to conduct important conservation work at key sites. Currently, there are still some deficiencies in the migration research of long-lived endangered birds such as cranes. In August 2018, two pairs (n = 4) of sibling juvenile White-naped Cranes (Antigone vipio) were tracked in Mongolia. Based on the tracking data, unusual migration routes of White-naped Crane were recorded during the juvenile and subadult stages. Three individuals died when exploring a new route during autumn migrations. These individuals used completely different spring migration routes each year in the juvenile and subadult stages, with the longest migration distance being approximately 4,495 km. There were significant differences in migration durations and stopover durations (P = 0.01) between spring and autumn migrations. Evidence of nocturnal migration by White-naped Cranes was recorded, and the longest continuous flight time recorded exceeded 19 hours. The results of this study will contribute to further understanding and research on the migration of this vulnerable species.

The ongoing panzootic of bird flu caused by high pathogenicity avian influenza (HPAI) virus is unprecedented in scale, with mass mortality events causing population level effects for several waterbird species. While the panzootic commenced in 2021, a number of key events have occurred over the past decades leading to the emergence of this viral lineage. Since 2021, tens of thousands of outbreaks have occurred affecting at least 320 species belonging to 21 orders, of which the vast majority are waterbirds. In this report we provide examples from across the globe associated with population level declines. Only Australia and Antarctica are unaffected, although this could change rapidly. Despite the carnage caused by mass mortality events, there are strategies to better protect waterbirds in both the short and long term. These include prevention of further spillover events from poultry, designing improved surveillance systems to both inform virus epidemiology and to benefit of all wild birds rather than only poultry (and humans), and respond appropriately to outbreaks in wildlife with necessary detail and resources. The loss of waterbirds at the current scale will not only be a conservation disaster, but also an ecological disaster, and therefore response to outbreaks in waterbirds must be prioritized.