Eleven family groups (n = 22 adults, 28 chicks) of North American Black Terns (Chlidonias niger surinamensis) were genotyped at four polymorphic loci in a pilot study to determine the genetic mating system of this socially monogamous species. Samples were collected between 2003 and 2008 at two colony sites in Wisconsin (USA) that differed in structural complexity of the breeding habitat and nest density, and from families in which the adult males (putative fathers) varied with respect to body condition. Thus, both ecological and individual variations were explored as possible factors influencing the extent of extra-pair paternity. No mismatched alleles were detected, however, between chicks and their putative parents, suggesting that extra-pair paternity is negligible in this subspecies. Despite the small sample size, the combined probability of detecting an allelic exclusion at one or more loci was 0.998, indicating sufficient power to detect a case of extra-pair paternity if it occurred. Data obtained from recaptures of adults banded over a 10-year period (2000–2009) indicated that inter-year mate retention was low (∼20%) and was observed only in pairs that remained together in consecutive years. No “divorced” mates of recaptured adults were encountered in subsequent years, suggesting that frequent mate switching is due more to the death or disappearance of the mate than to intentional dissolution of the pair bond. The results of this pilot study provide the first evidence of genetic monogamy in Black Terns and suggest that low mate fidelity is related to low breeding site fidelity, a characteristic common in birds that breed in unstable habitats.

Although the prey of Reddish Egrets (Egretta rufescens) generally consists of shallow-water, euryhaline fish species, rangewide differences in breeding season diet have not been examined. Furthermore, the relative proportions of the two Reddish Egret color morphs vary from east to west across the species' range. Color morph may influence foraging efficiency, but variations in prey across the species' range and between morphs is undocumented. By examining boluses from Reddish Egret (n = 109) nestlings, prey species proportions were compared between morphs, among regions and among colonies within Texas. Between regions, prey species and proportion of species differed widely; however, fish species with similar life histories were selected across the Reddish Egret's range (Bahamas: 100% sheepshead minnow (Cyprinodon variegatus); Texas: 85% sheepshead minnow; Baja California Sur: 49% American shadow goby (Quietula y-cauda); Yucatán: 64% Yucatán pupfish (C. artifrons)). Within the Laguna Madre in Texas, significant differences in prey species were not detected between morphs (F_(1,61) = 1.36, P = 0.224); however, prey mass by species differed between colonies (F_(1,60) = 2.68, P = 0.010). While our results only pertain to Reddish Egret diet during the breeding season, this study increases our understanding of Reddish Egret ecology and provides initial diet information across the species' range.

Because Belted Kingfishers (Megaceryle alcyon) eat a diet comprised primarily of fish they are a useful indicator species for aquatic contaminants such as mercury. Monitoring efforts generally compare nesting success or tissue contaminant concentrations from contaminated sites with reference sites. In contrast, this study examined subtler potential effects of mercury accumulation by quantifying plumage coloration (structural and melanin based) of nesting adult Belted Kingfishers and relating it to individual mercury concentrations. Mercury exposure was associated with increased brightness of plumage color consistent with the hypothesis that mercury slows the production of melanin. Clear sex differences in the chroma and hue of blue body feathers identified during this study suggest that Belted Kingfishers possesses cryptic dimorphism beyond the rufous “belt,” and thus mercury-induced alterations in blue plumage could reduce fitness.

The Torrent Duck (Merganetta armata) is one of four species of waterfowl that live in fast flowing rivers. Torrent Ducks feed on benthic invertebrates in mountain rivers from Venezuela to Argentina. Prey selection by Torrent Ducks was investigated by comparing the proportion of prey taxa in their feces with the proportion available in river benthos. Feces and benthos were sampled during spring and autumn at sites with different precipitation levels in northwestern Argentine Patagonia. Energy values of the most important prey items were evaluated and the results adjusted for the amount of chitin body proportions. The average energy value of each individual prey item was 3.60 J in Gripopterygidae, 5.88 J in Simuliidae, 11.48 J in Atalophlebiinae and 12.25 J in Smicridea spp. These four invertebrate taxa represented approximately 80% of Torrent Duck diet. Prey availability and energy value alone could not explain the total Torrent Duck diet, and it was necessary to consider other factors such as aspects of prey natural history and their distribution in the benthos. Most consumed items were filter-feeding species (Simuliidae and Smicridea spp.) that inhabited rock surfaces that were more accessible to Torrent Ducks. Gripopterygidae and Atalophlebiinae were less accessible as they inhabit in the lower part of rocks. Diet information can be used to assess the availability of the most important prey items of Torrent Ducks in different rivers, and thus to estimate an important feature of habitat quality.

By 2013, six of 27 Black Terns (Chlidonias niger) from four Dutch colonies that had received light level geolocators in 2010–2011 had been recaptured. All six recovered individuals migrated to West Africa, but whereas one individual flew there nonstop, the others made stops of varying length en route. These included flights of 2,000–6,000 km between major stopovers, achieving travel speeds over 1,000 km/day. In addition to the single previously known postbreeding stopover, Lake Ijsselmeer, this work revealed postbreeding stopovers at the Alborán Sea, the seas near the Canary Islands and at the Banc d'Arguin, Mauritania. Staging durations varied between 2 and 35 days, and the longer the staging took, the longer the subsequent flights were. In the West African nonbreeding region, the Black Terns with geolocators staged at the Banc d'Arguin, the marine continental edge seas between Senegal and Liberia, and the Gulf of Guinea, or went as far south as the Benguela Current off Namibia. Most birds spent most of their time far offshore. Northward migration for the three birds with active geolocators took 38–39 days with staging episodes near the Canary Islands and in the Mediterranean west of Italy. One individual crossed the Sahara from Senegal to northern Algeria in 3 days. After arrival in Europe, travel speeds were lower than when in transit from West Africa. Even with a sample size of six, we showed that Black Terns are long-distance migrants with substantial individual variation in migration patterns, including the use of staging sites, stopover times and travel distances. The variation in itineraries may imply that the distribution of the marine resources they rely on are relatively unpredictable. It remains to be seen whether the variability seen here reflects differences in otherwise fixed individual strategies or whether Black Terns are truly highly flexible.

Rynchops niger intercedens, one of the South American subspecies of the Black Skimmer, is a widely distributed neotropical bird for which many ecological aspects, such as migratory routes and site fidelity, are unknown. Two distinct breeding phenologies have been reported for this subspecies, which may create the genetic isolation of populations. Six microsatellite loci were used to study the genetic structure of the Black Skimmer in southern South America, comparing breeding populations from Brazil and Argentina and individuals from the main nonbreeding site at Argentina. A weak genetic differentiation between colonies, although statistically significant, was observed. This low genetic structure (despite different breeding phenologies) could be explained by demographic history of these populations and/or the effect of a very important non-breeding site in southern South America shared by these populations. Further studies applying a broader range of molecular markers plus improvement of extant banding efforts are required to better understand the dispersal mechanisms of this species.

The first information on the morphometry and sexual size dimorphism of the sympatric South American (Sterna hirundinacea), Cayenne (Thalasseus sandvicensis eurygnathus) and Royal (T. maximus maximus) terns from the Patagonia region in Argentina is provided, and a discriminant analysis to sex the three species is used. Morphological characters were obtained from South American Terns (n = 83), Cayenne Terns (n = 63) and Royal Terns (n = 20). All species were sexed using polymerase chain reaction-based molecular techniques. Sexes in the three tern species were only slightly dimorphic in size. Male Cayenne and South American terns were significantly larger than females in bill length, bill depth and head length. Royal Terns, in contrast, showed a high overlap in most morphological measurements, with head length being the only measurement that differed significantly between sexes. Head length correctly sexed 89% of South American Terns and 75% of Royal Terns, while a function including bill depth and head length correctly sexed 78% of Cayenne Terns. Our results provide a valuable tool for rapid sexing in the field of these three Patagonian terns, although reliable sexing in Cayenne and Royal terns should be preferentially achieved using a combination of morphometric and molecular sexing.

The Reddish Egret (Egretta rufescens) is the rarest and least studied species of heron in North America and is a species of conservation concern throughout its range. Foraging behavior and foraging success of the Reddish Egret were studied by focusing on whether their foraging behavior or success varied with age, color morph, group size, and habitat measures. Foraging individuals (n = 372) were video-recorded in the Laguna Madre of Texas, USA, from March 2008-April 2010. Adult Reddish Egrets were 30–250% more successful foragers than juveniles, and groups were 32–44% more successful foragers than solitary foragers. Foraging success was similar between color morphs. The more specialized foraging behaviors of canopy feeding, wing flicking, and foot-stirring had the highest success, but were employed infrequently. Four environmental variables (wind speed, light intensity, water depth, and percent seagrass coverage) were found to influence foraging success, but accounted for only 3% of the variation in foraging behavior. Our results suggest that environmental variables have little influence on foraging behavior of Reddish Egrets in the Laguna Madre, and we suggest that characteristics of the prey have a stronger influence. An understanding of how environmental variables influence foraging behavior and success may allow us to better assess habitat quality or possibly aid in identification of highly productive foraging sites and allow for more targeted conservation actions to those habitats that promote high foraging success.

Little is known about migration of Magellanic Penguins (Spheniscus magellanicus) in the Pacific Ocean. We used satellite telemetry to determine the post-breeding movement patterns of recently molted male Magellanic Penguins (n = 6) at Puñihuil, southern Chile, in 2006. Five individuals went north, stopping at two separate wintering areas along the coast, while one went 300 km south to waters inland of the island of Chiloé, Chile. The most commonly used wintering area (n = 3) was 600–800 km north of the breeding colony, near the Gulf of Arauco, Chile, where high levels of primary productivity are common. Magellanic Penguin wintering areas coincided with important areas for other seabirds and overlapped with human fisheries.

A combination of infrared cameras and plasticine eggs were used to identify potential nest predators of Flightless Steamer-Ducks (Tachyeres pteneres) and Flying Steamer-Ducks (T. patachonicus) and to evaluate the relative efficacy of these methods for identifying predators. Cameras were set up at 31 artificial nests with plasticine eggs and at four Flightless and two Flying steamer-duck nests. Two avian predators, Chimango Caracara (Milvago chimango) and Southern Crested Caracara (Caracara plancus), and two mammalian predators, Fuegian Culpeo fox (Pseudalopex culpaeus lycoides) and American mink (Neovison vison), were identified as depredating artificial nests from photos. Active Flightless and Flying steamer-duck nests were found only on islets, and from the photos the Chimango and Southern Crested caracaras were identified as nest predators. Mammalian predators were not photographed on islets (neither on artificial nor natural nests). Though the potential predator community at Lapataia Bay was small, there were considerable similarities in physical evidence and marks left at nests, especially within avian predators. Also, depredated nests were sometimes revisited by other predators and these multi-predator visits sometimes caused changes to the appearance of the depredated nest following departure of the initial predator. The cameras provided an objective method for definitive identification of nest predators.

As young seabirds approach independence, a range of tactics are sometimes employed in an attempt to secure additional food items prior to departing the nest. Detailed here are previously unreported kleptoparasitic and predatory behaviors of juvenile Brown Boobies (Sula leucogastei) on Ashmore Reef in the Timor Sea. From 14–20 November 2013, the number of Greater Crested Terns (Thalasseus bergii) breeding adjacent to a Brown Booby colony was reduced from 128 adults attending the colony to 59 adults. During this time, two juvenile Brown Boobies were observed depredating the eggs of the Greater Crested Terns and ingesting prey regurgitated by Greater Crested Terns. The factors that lead to this unusual foraging behavior in juvenile Brown Boobies are not known; however, low body mass and hunger may play a role. Repeated years of predation of Greater Crested Tern eggs by Brown Boobies could lead to the abandonment of this colony.

To better understand how time of day and light level affect foraging patterns and feeding success in a primarily nocturnal wading bird, observations were made on Black-crowned Night-Herons (Nyticorox nycticorax) at an artificial weir located in the Little Arkansas River in Wichita, Kansas. Numbers of foraging birds at the weir were recorded using intervals of 1-hr periods during both day and nighttime. Strike rates, capture rates, relocation rates, prey sizes, and rates of aggression were compared. A similar number of Black-crowned Night-Herons used this site during the day and at night. Also mean strike rates, capture rates, and relocation rates did not differ between day and night. However, focal birds captured significantly larger fish during the day, when they also experienced higher rates of intra- and interspecific aggression. Since basic foraging patterns did not differ by time of day, it is likely that differences in the behavior, detection, and availability of prey account for the capture of larger fish during the day than at night. Diurnal foraging activity by Black-crowned Night-Herons appears to be important in meeting increased energy demands during the breeding season.

Hepatic mercury concentrations of Pectoral Sandpiper (Calidns melanotos) and Killdeer (Charadrius vociferus) collected from the central Illinois River Valley, Illinois, during early fall migration in 2007 were examined. Mean and median mercury concentrations were significantly greater in the livers of Pectoral Sandpipers (0.30 and 0.28 µg/g wet weight, respectively) than in Killdeer (0.07 and 0.06 µg/g wet weight, respectively). Differences in foraging ecology between these species likely account for the observed differences in tissue mercury concentrations. In general, mercury concentrations were low in these species relative to other shorebirds and can serve as baseline for future monitoring.