Environmental changes in estuaries resulting from resource use and management actions can detrimentally affect waterbirds. This study examined the distribution and abundance of 54 waterbird species from 1992 to 2010 in six intensively used and managed estuarine waterbodies, relative to four environmental variables (salinity, turbidity, depth variability and submerged macrophyte biomass) undergoing periodic and directional changes. Multivariate analyses enabled distinctions to be made between waterbirds associated with environmental conditions characteristic of either estuaries or estuarine lakes, and revealed spatial and temporal differences in waterbird abundances between and within waterbodies. Ducks and grebes were more abundant in low salinity deeper waterbodies, while waders, cormorants and gulls were more abundant in high salinity shallow waterbodies. Higher quantity and quality of food sources attract herbivorous waterbirds to saline lakes rather than estuaries. Water depth variability influences accessibility of feeding areas, with decreased variability in water levels increasing habitat suitability for herbivores, and reduced open periods in the estuaries decreasing habitat suitability for waders. Turbidity did not significantly influence the distribution of waterbirds, whereas disturbance from human activities and vegetation of sandbanks were considered to be important factors. The estuarine lakes systems provide a mosaic of different habitat conditions, essential for maintaining a diverse waterbird community.

Wading bird prey populations, prey availability and wading bird nesting success are all thought to be associated with hydrologic conditions in wetlands, but the relationship between successful nesting and essential prey types fed to chicks is poorly understood in many cases. Prey fed to White Ibis (Eudocimus albus) chicks were quantified and compared for three colonies in the northern Everglades within and between the 2008 and 2009 nesting seasons. Crayfish were the dominant prey type in both years, being present in 58–88% of chick boluses across all collections. Prey composition was not temporally variable within 2008, but chick diet shifted slightly toward more fish at the end of 2009 when the wetland w^ras at its driest. Crayfish were the dominant (55–65%) energetic component of White Ibis chick diets in the northern Everglades during both a good nesting year (6,000 nests) with higher water levels (2008) and during an excellent nesting year (9,300 nests) when water levels were lower (2009). The results from this study and an earlier study suggest fish, along with terrestrial insects and urban refuse are only secondary prey for nesting White Ibis and that wetlands with abundant crayfish populations should promote high nesting effort.

Since the 1970s, artificially stabilized water levels, increased presence of common carp (Cyprinus carpio) and invasion by a cattail hybrid (Typha × glauca) have changed the nesting environment for Western Grebes (Aechmophorus occidentalis) at Delta Marsh, Manitoba. To evaluate the impact of these changes, nest survival rates, causes of nest mortality, wind conditions, locations of nests and vegetation structure at nests in 2009–2010, and chick-adult ratios were compared to similar data for Western Grebes at Delta Marsh from 1973–1974. Apparent nest survival rates were lower in 2009–2010 than 1973–1974, and between low-water years (1973, 2010) and high-water years (1974, 2009). Lower apparent nest survival rates in 2009–2010 (49% in 2009 and 43% in 2010, compared to 46% in 1973 and 84% in 1974), and chick-adult ratios (0.55 in 1973 and 0.88 in 1974, compared to 0.55 in 2009 and 0.39 in 2010) were attributed to increases in destruction of nests primarily by wave action and secondarily by common carp, which were not observed destroying Western Grebe nests in 1973–1974. The replacement of native bulrushes by cattails in Western Grebe nesting habitat may have caused the observed increase in proximity to openwater edge, and this proximity may have increased destruction of nests by waves. Restoring stands of emergent bulrush by varying marsh water levels and reducing carp in the marsh might improve nest survival of Western Grebes.

The endangered Hawaiian Petrel (Pterodroma sandwichensis) is endemic to the main Hawaiian Islands where it nests in underground burrows surrounded by vegetation that varies greatly from island to island. Information regarding island-specific nest site selection and habitat characteristics is important when considering the management needs of the species, including control of invasive plants and protection from introduced predators. Extensive search efforts, using nocturnal vocalization and visual surveys, resulted in locating 71 nesting burrows on the Island of Lāna'i. Logistic regression was used to examine the influence of elevation, planar curvature, percent slope, canopy cover, and vegetation type on nest site locations. The top model in predicting Hawaiian Petrel nest site selection was influenced by increasing slopes, an understory dominated by native vegetation, and open canopy. The top model was supported by a model weight (w_i) of 0.53, with the second model holding most of the remaining weight (w_i = 0.19) and including elevation as a predictor. Native understory vegetation, dominated by Uluhe ferns (Dicranopteris linearis and Diplopterygium pinnatum), may provide some protection from introduced mammalian predators. Using high resolution imagery and remote sensing techniques, we quantified the remaining native vegetation on Lāna'i. With less than 300 ha of upper elevation (> 600 m) native forest remaining, management priority should focus on reducing the spread of invasive vegetation that is quickly dominating nearby Hawaiian Petrel nest sites.

With global loss of natural wetlands, managed wetlands increasingly support energy requirements for wintering shorebirds and waterfowl. Despite numerous studies of avian bioenergetics in freshwater systems, less is known of the energetic capacity of estuarine systems. In San Francisco Bay, managed saline ponds converted from former commercial salt evaporation ponds form part of the largest wetland restoration project on the Pacific coast of North America. A daily-ration model was applied to assess carrying capacity for diving ducks and shorebirds during four winter seasons (2007–2010) in seasonal and circulation ponds, each in two salinity classes. Diving ducks comprised an estimated 35,450 ± 1,559 ( ± SE) in average years and 45,458 ± 1,653 in peak years with > 95% in circulation ponds. Shorebirds comprised 64,253 ± 14,838 ( ± SE) in average years and 108,171 ± 4,854 in peak years with > 64% in seasonal ponds. Macroinvertebrate energy density was highest in mesohaline (5–30 ppt) circulation ponds and lowest in seasonal ponds for both guilds. Energy requirements for diving ducks in mesohaline followed by low-hyperhaline (30–80 ppt) circulation ponds were mostly met by available prey energy. Available energy for shorebirds was substantially less than they required in seasonal ponds but exceeded their needs in mesohaline circulation ponds. Mesohaline circulation ponds supported 9,443 ± 1,649 ( ± SE) shorebird use-days·ha^-1 of accessible habitat and 2,297 ± 402 diving duck use-days·ha^-1 of accessible habitat, twice the capacity of low-hyperhaline circulation ponds and greater than five times that of seasonal ponds for both guilds. Our results indicated that reducing salinity to mesohaline levels and altering water depth to increase accessibility substantially increased energy available for these species in estuarine managed ponds.

Due to its secretive nature and nocturnal vocalization, multi-species bird monitoring programs are not effective in surveying populations of Yellow Rails (Coturnicops noveboracensis) and, thus, species-specific survey methods should be used. To determine how to optimize nocturnal call-playback surveys of Yellow Rails, we evaluated the effects of survey methods (naïve-estimated vs. detectability-adjusted estimated occupancy, observer, number of surveys, and the use of playbacks) and temporal and environmental conditions (e.g., time, date, temperature, moon phase, seasonality, and cloud cover) on detection probability. In 2010 and 2011, 334 call-broadcast night surveys for Yellow Rail were conducted at 167 survey points within 80 wetlands in south-central Manitoba, Canada. Yellow Rail detection probability was estimated at 0.63 in both years. In 2010, the detectability-adjusted wetland occupancy rate was estimated at 0.63, and in 2011 it was estimated at 0.36. Call-broadcast surveys contributed relatively little to improving Yellow Rail detectability, but repeat surveys at each site increased the number of individuals detected. Detection probability was not correlated with the temporal or environmental variables we studied, or by observer. Surveys where call-broadcasts are not feasible, such as volunteer surveys, are still likely to result in good estimates of Yellow Rail abundances, if surveys are repeated within breeding seasons.

The Olrog's Gull (Larus atlanticus) is a species that feeds almost exclusively on intertidal crabs. The influence of feeding technique, food source, and habitat characteristics on the feeding rate of breeding individuals was examined at Bahía San Blas, Argentina, from September to December 2007. Olrog's Gulls used four feeding techniques, with more prey captured by pecking than by peck-digging, head submergence, or up-ending. Olrog's Gulls fed throughout the tidal cycle using different intertidal zones when they were exposed and covered by water. However, feeding techniques used in exposed intertidal areas (pecking and peck-digging) resulted in significantly higher feeding rates. Feeding rate increased with average prey density and was higher when feeding in structured environments, characterized by the presence of rocks or oysters and high densities of the intertidal crab Cyrtograpsus altimanus. The burrowing crab Neohelice granulata is the main component of the Olrog's Gull diet during most of the breeding cycle. Although average density of N. granulata in feeding patches was lower than that of C. altimanus, body size of the former was significantly larger and energy density of individuals higher, resulting in a higher energy profitability of unstructured habitats. Prey switching toward C. altimanus during the young chick stage observed in previous studies may result from the need to feed chicks with smaller prey.

White-headed Steamer-Ducks (Tachyeres leucocephalus) are flightless waterfowl endemic to a small section of coastline in Patagonia, Argentina. This study provides the first detailed information on White-headed Steamer-Duck diet composition, foraging behavior and prey availability. This study was conducted in the northern San Jorge Gulf, Patagonia, during 2007. Fifteen feeding territories were identified, and food availability was quantified within them and also within unused areas. A total of 45 feces were analyzed to determine diet composition, and foraging behaviors of females were monitored. Benthic community diversity differed between territories and non-territories. Overall, diversity and invertebrate abundance tended to be higher in territories. Ten invertebrate prey taxa were identified in adult diets, and the most frequent prey in feces were crabs, mussels, and ragworms. Head-neck dipping was the most common method of feeding. Our results improve the understanding of the relationship between diet, selection of areas with special invertebrate availability and foraging techniques used to access and exploit the resources.

Black-necked Cranes (Grus nigricollis) wintering at Dashanbao Nature Reserve in southwestern China were studied to document for the effects of flock size and position on the level of vigilance. The time spent on vigilance, scanning frequency and scanning duration decreased significantly with flock size for individuals positioned both in the center of the flock and at its periphery. However, the decrease in time spent on vigilance and scanning frequency following the increase in the flock size happened more rapidly for individuals in the center of the flock than those at the periphery. The decrease of the three parameters related to flock size significantly correlated with position. The time spent on vigilance and scanning frequency significantly correlated with the flock size and position, but not with scanning duration. Consequently, the number of individuals preferring central positions in the flock (a phenomenon known as “edge effect”) was increased by the increase in flock size for Black-necked Cranes in winter.

Double-crested Cormorant (Phalacrocorax auritus) foraging locations in northern Lake Michigan were recorded in 2003 and 2010. In the interim, the invasive round goby (Neogobius melanostomus) appeared in 2006, and control of Double-crested Cormorants was initiated in 2007. Spatial data from 2003 and 2010 were analyzed to determine whether foraging distributions differed between sample periods. A multi-response permutation procedure found that a significant shift in foraging locations occurred between sample periods. Groups of Double-crested Cormorants foraged in the same key locations in both years, but foraging range expanded overall in 2010. Range expansion could be a response to the presence of the round goby, which is an abundant food source throughout Lake Michigan. The 2010 foraging location data corresponded with the early departure of Double-crested Cormorants from the Beaver Archipelago. The combined effects of control and the appearance of round goby in diets resulted in changes in numbers and distributions of foraging Double-crested Cormorants.

The first evidence of breeding of Marbled Duck (Marmaronetta angustirostris) in Libya, North Africa, is reported. In June 2012, at Mallaha wetland, in Tripoli, Libya, two dead ducklings were found that were later genetically identified as Marbled Duck. This breeding evidence suggests that this and other duck species may breed elsewhere in Libya. Better knowledge on Libyan, and more generally on north African, waterbirds is needed to document the population size and the status of these species. Such information will be important to secure the future of threatened species, such as the Marbled Duck.

Restoration and the creation of artificial wetlands can mitigate the loss and degradation of natural wetlands. The chief wetland areas in northern Iberia are the estuaries situated along the coast of the Bay of Biscay. These areas are tidal in nature and often small in size. These characteristics, together with high levels of human, disturbance can cause significant limits on the conservation of waterbirds. At the end of 2009, an old polder within the Urdaibai marshes in Spain was modified to create an artificial lagoon (Orueta Lagoon). The goal of this study was to evaluate the use of this lagoon by waterbirds, and its contribution to waterbird assemblage and richness at Urdaibai. Orueta Lagoon contributed 26.8% of total abundance, including 11 species not present in other zones of Urdaibai. Thus, it provided a new and attractive habitat for several waterbird species, especially ducks, coots and allies, shorebirds and grebes. Therefore, Orueta Lagoon plays a fundamental role in the enrichment of the waterbird assemblage at Urdaibai and hence is of great value from a conservation standpoint.