The geographic distribution and populations of cliff-nesting seabirds are essential elements in the assessment of their ecological roles and status. Here, a geographic mapping approach was used to visualize the biogeography of European seabirds. This approach was conducted at two temporally separated time intervals: 2004–2010 was compared to 1982–1988. Three biogeographic regions were identified: Arctic, Boreal and Ibero-Atlantic. The data show that species richness has remained stable over the approximately 20-year interval, as have, in general, population numbers and geographic distribution. Such stability, compared to recent declining trends worldwide, may be due to earlier human-driven declines in the European Atlantic, followed by effective conservation measures for the remaining populations. The species richness of cliff-nesting seabirds may not be principally determined by island area and distance from a large land mass, but rather by the extent of vertical cliff façade and distance from fishing areas. The stable species richness of each European Atlantic geographical sub-unit suggests that not only individual islands and mainland but rather the entire European Atlantic functions as a single large “cliff seabird island” in determining biogeographic seabird equilibrium.

Eleven of 15 species of cranes (family: Gruidae) are considered vulnerable or endangered, and the increase of agriculture and aquaculture at the expense of natural wetlands and grasslands is a threat to Gruidae worldwide. A reintroduced population of Whooping Crane (Grus americana) was studied in coastal and agricultural wetlands of Louisiana and Texas, USA. The objectives were to compare Whooping Crane movements across seasons, quantify multiscale habitat selection, and identify seasonal shifts in selection. Whooping Cranes (n = 53) were tracked with satellite transmitters to estimate seasonal core-use areas (50% home range contours) via Brownian bridge movement models and assess habitat selection. Whooping Crane core-use areas (n = 283) ranged from 4.7 to 438.0 km², and habitat selection changed seasonally as shallow water availability varied. Whooping Crane core-use areas were composed of more fresh marsh in spring/summer, but shifted towards rice and crawfish (Procambarus spp.) aquaculture in the fall/winter. Within core-use areas, aquaculture was most strongly selected, particularly in fall when fresh marsh became unsuitable. Overall, the shifting of Whooping Crane habitat selection over seasons is likely to require large, heterogeneous areas. Whooping Crane use of agricultural and natural wetlands may depend on spatio-temporal dynamics of water depth.

The Reddish Egret (Egretta rufescens) is North America's rarest heron, and roughly 10% of its population resides in Florida. Its dark plumage, subcanopy nesting, and rarity make it difficult to count with aerial surveys, and assessments of ground- and boat-based methods for estimating the abundance of nesting pairs at breeding sites in Florida are lacking. The efficacy of flight-line surveys (boat-based counts of adults flying to and from colonies) and direct counts (ground- or boat-based counts of nests) were compared using data collected by multiple observers during repeated visits to 16 Reddish Egret colonies in three core breeding areas in the State of Florida, USA. Detection rates on direct counts were 77% for a single observer and 89% for two observers combined. Variance between repeated flight-line surveys was high (61%) for 1-hr surveys but substantially lower for 2-hr (18%) and 3-hr (14%) surveys. Estimated nest counts from flight-line surveys were substantially greater than those produced during direct counts, with mean differences of 85% for 1-hr counts, 134% for 2-hr counts, and 133% for 3-hr counts. Overestimates from flight-line surveys may be related to factors that can be mitigated by avoidance of sites for which use of the method is likely inappropriate (e.g., where breeding is substantially asynchronous or when a site includes an interior foraging lagoon). Survey recommendations are presented for monitoring the Reddish Egret on a large spatial scale.

In northwestern Italy, traditional rice cultivation using permanent flooding has been replaced by cultivation that uses a reduced water depth and a shortened submersion period. Prey availability for the numerous herons and egrets using this intensive rice cultivation region changed as well, with a diminution of amphibians and an increase of crayfish (Procambarus clarkii) and oriental weatherfish (Misgurnus anguillicaudatus). The prey intake in 2014 was compared with data available for 1987 for the three most common species of waterbirds that forage in the paddies. Total biomass intake by Grey Herons (Ardea cinerea) feeding in the paddies decreased from 28 g dry mass/min in 1987 to 7 g in 2014, and by Black-crowned Night-Herons (Nycticorax nycticorax) from 8 g to 5 g, while the intake by Little Egrets (Egretta garzetta) remained similar (12 and 13 g in 1987 and 2014, respectively). The observed levels of prey intake allowed breeding Grey Herons to meet their energy needs by feeding exclusively in the rice paddies in 1987, but not in 2014. The other two study species could not meet their daily requirements for successful breeding by feeding in the paddies only, either in 1987 or 2014. Yet the three species bred successfully in the study area, and their reproductive output remained stable both in 1987 and 2014. Successful breeding was probable by the three species foraging in other habitats, such as rivers, small natural wetlands and irrigation canals, in the region.

Body mass accumulation is a widely used measure of waterfowl condition and predictor of fitness. So far, however, post-breeding changes in body mass affecting autumn and winter condition have been largely unexplored. Here, changes in body mass of Pink-footed Geese (Anser brachyrhynchus) were investigated during an autumn stopover in Nord-Trøndelag, Norway. Average juvenile body mass varied from year to year, ranging from 1,976–2,286 g and 2,154–2,404 g for females and males, respectively, and was affected by May temperature on the breeding grounds—a proxy for onset of the breeding season. Average adult body mass did not vary between years. During the stopover, juveniles of both sexes increased their body mass substantially (11.4 ± 2.8 g/day), while adult birds showed sex-specific differences. Adult males took on an average of 6.1 ± 2.4 g/day, whereas adult females showed no increase during the period. One explanation of this might relate to sex-specific behaviors in the preceding brood-rearing period. In addition, arrival from the breeding grounds was earlier for non-breeders compared to family groups. Our findings indicate that annual variation in body mass, as well as body mass changes during an autumn stopover, may differ considerably between age and sex classes of Pink-footed Geese.

Information about shorebirds is essential for predicting the impact of natural and human-mediated changes on their populations. Aerial and terrestrial surveys were performed to characterize shorebird abundance, spatial distribution and assemblage composition at Samborombón Bay, Argentina, during different tide levels and seasons. Approximately 60,000 shorebirds were observed using the intertidal flats. Highest abundances occurred during austral summer, autumn and spring when Nearctic migrants dominate the assemblage. Significant percentages (> 1%) of the populations of three Nearctic migrants [American Golden-Plover (Pluvialis dominica), Hudsonian Godwit (Limosa haemastica), and White-rumped Sandpiper (Calidris fuscicollis)], one Neotropical migrant [Two-banded Plover (Charadrius falklandicus)], and two resident species [American Oystercatcher (Haematopus palliatus) and Black-necked Stilt (Himantopus mexicanus)] were estimated. Large numbers of Semipalmated Plovers (C. semipalmatus), Rufous-chested Dotterel (C. modestus), and Ruddy Turnstones (Arenaria interpres) were also recorded. Management measures aimed at maintaining healthy, viable populations should address species needs during all four seasons focusing on the southern and central sectors of Samborombón Bay, which are the most important feeding areas for shorebirds.

The nestling diets of four heron species breeding on a small forestry islet in Anzali, Iran, were investigated to determine the dietary segregation among sympatric breeders. Regurgitated samples from Black-crowned Night-Herons (Nycticorax nycticorax), Little Egrets (Egretta garzetta), Cattle Egrets (Bubulcus ibis) and Squacco Herons (Ardeola ralloides) were collected during the breeding season from 23 May to 16 August 2016. A total of 1,606 prey items were identified representing 39 prey categories from nine different classes. Differences were detected among these four ardeid species for the percentage of each prey category. Fish dominated the regurgitates of the Blackcrowned Night-Heron (67%; n = 43 samples), Little Egret (45%; n = 33 samples) and Squacco Heron (53%; n = 10 samples), whereas arachnids and insects combined (53% and 40%, respectively, based on total number of individuals) and insects (61.9% based on weight) were the most common prey items for the Cattle Egret. Although fish items were dominant in Black-crowned Night-Herons, Little Egrets and Squacco Herons, their weight (χ²₃ = 318, P < 0.001) and length (χ²₃ = 225.2, P < 0.001) differed significantly. There was some overlap in the diet of all four heron species, especially between Black-crowned Night-Herons and Squacco Herons, with a Pianka Overlap Index equaling 0.92. There was sufficient dietary segregation in terms of number, weight and length of prey items that could contribute to a reduction in competition for limited food resources.

Gull-billed Terns (Gelochelidon nilotica) have historically demonstrated variability in nest-site selection and reproductive success throughout their breeding range. However, few studies have investigated the breeding parameters of Gull-billed Tern populations on barrier islands in the northern Gulf of Mexico, USA. The main objective of this study was to investigate annual variability of breeding population size, hatching success, and causes of nest failure during eight breeding seasons (2009–2016). Annual variation was observed in colony sizes (Range = 1–68 nests), colony locations (among five islands), and hatching success (0–93%). Mean hatching success was 56% and flooding was the main cause of failure, accounting for 64% of all failed nests. Additionally, nest site habitat characteristics were compared between successful and unsuccessful Gull-billed Tern nests. Nest substrate composition differed between successful and failed nests, and successful nests were also associated with higher elevation, greater distance from the high tide line, and less vegetative cover. There was considerable variation in Gull-billed Tern breeding population size and hatching success, which may be attributable to the dynamic nature of barrier island habitats. Long-term monitoring is required to better understand the breeding dynamics of Gull-billed Terns, but conservation efforts should consider maintaining island habitats that are protected from flooding and have adequate nesting substrate, minimal vegetation, and limited disturbance from humans and predators.

Research comparing dive durations and inter-dive intervals of stiff-tailed diving ducks, which is important for understanding differences in species ecology, is lacking for the non-migratory Masked Duck (Nomonyx dominicus) and West Indian Ruddy Duck (Oxyura jamaicensis jamaicensis), and the migratory Northern Ruddy Duck (Oxyura jamaicensis jamaicensis). Although the Northern Ruddy Duck and West Indian Ruddy Duck are considered the same species, we treated them separately to evaluate possible ecological differences. All three were observed at the same time in the same place in Laguna Cartagena National Wildlife Refuge, Puerto Rico. Dive durations and inter-dive intervals were recorded for Masked Duck (n = 60), Northern Ruddy Duck (n = 70), and West Indian Ruddy Duck (n = 445) from 1 January through 30 April 2015 and 2016. The Northern Ruddy Duck had a longer mean (± SE) dive duration (22.9 ± 0.75 sec) than the West Indian Ruddy Duck (18.8 ± 0.02 sec). Northern Ruddy Ducks likely had longer dive times because of their larger body size and migratory behavior.

Behavioral and genetic data were used to determine whether more than one female lays eggs in nests of the Cattle Egret (Bubulcus ibis). Eighty-five nests were monitored, and 18 nests with eggs suspected to be from different females were selected. Both types of eggs were swabbed to sample for DNA since eggshells contain cells from the reproductive tract of the mother or the skin of incubating individuals. Using these swabs, molecular sexing was first conducted, and three clutches were discarded due to samples with a pattern of male DNA. In the remaining 15 nests, DNA was extracted from swabs (n = 45 eggs) and genotyped at seven microsatellite loci. The genetic diagnosis was developed with a blinded protocol including both suspected and non-suspected eggs by comparison of maternal DNA found on the eggs. With one exception, genotypes not compatible with the predominant female genotype in each clutch were found almost exclusively on suspected eggs, proving that the genetic diagnosis was not an artifact. Using a behavioral criterion, multiple laying females were detected in 21.1% nests, but genetic data showed that the behavior methodology should be modified. In the 15 nests analyzed, the behavioral criterion failed to detect one suspected egg in one nest ( #11) (false negative) and indicated two suspected eggs in two nests (#12 and #13) that were not confirmed using the genetic criterion (false positives). The results showed that estimates based solely on the behavior approach can be biased, and the genetic method should be applied to check and improve ecological data.

The Masked Finfoot (Heliopais personatus) has a global population estimated at 1,000 individuals, but very little is known about its ecology. Therefore, the nesting ecology of the Masked Finfoot was studied in the Sundarbans of Bangladesh between 2011 and 2014, and compared to nesting observations from the same area made in 2004. A total of 25 nests were detected in 2011–2014: 56% (n = 14) on blinding mangrove (Excoecaria agallocha), 36 % (n = 9) on sundri (Heritiera fomes) and 8% (n = 2) on cannonball mangrove (Xylocarpus granatum). Factor analysis revealed that 2004 nest characteristics differed from subsequent years. The 2011–2014 nests were built on the periphery of vegetation along narrow creeks of 12.66 ± 3.54 m and located 1.78 ± 0.53 m above water level at high tide. Diameter of nesting tree (2004 = 16.68 ± 5.82, 2011–2014 = 34.19 ± 3.96), nest depth (2004 =16.88 ± 3.09, 2011–2014 = 13.28 ± 3.32) and creek width (2004 = 21.26 ± 9.09, 2011–2014 =12.66 ± 3.54) was significantly different between 2004 and 2011–2014. Reasons for changes in nesting locations are important to determine given the conservation status of the species and altering conditions in the Sundarbans.

Precise sampling and observational techniques are fundamental to the management and conservation of many bird species. An array of camera traps (n = 15) was deployed to collect information on a poorly known wetland bird, Lewin's Rail (Tasmanian) (Lewinia pectoralis brachipus) on Tasman Island, Australia, from 25 August 2012 to 10 June 2013. Using camera traps located to maximize detection probability, images from 1,213 camera events quantified Lewin's Rail occurrence and temporal variation in activity. Observations of social organization and behavior, agonistic behavior, foraging, relations within family groups, breeding activity, and diel activity were recorded. Lewin's Rail behavior was documented for a total of 294 days (n = 3,975 camera trap days). This study demonstrates the effectiveness of camera traps as a tool for studying secretive ground-dwelling birds. Although camera traps cannot replace other avian survey methods, they provide a complementary method for collecting behavioral data on Lewin's Rail and other ecologically similar species.