Migrating shorebird populations using approximately 2% of Louisiana and Texas Gulf Coastal rice fields were surveyed during spring migration (March–May of 1997 and 1998) using biweekly stratified random surveys conducted at 50 roadside survey points and approximately 30,000 shorebirds were observed. Shorebird counts were extrapolated and almost 1.4 million birds in 1997 and over 1.6 million birds of 31 species in 1998 were estimated to use rice field habitat for stopover sites in Louisiana and Texas. Greater than 50% of the estimated North American populations were estimated to use rice field habitats for five species, including a species of concern, Buff-breasted Sandpiper (Tryngites subruficollis) at 187%. Because of predictability of suitable rice field habitat acreage, timing of field preparation and water availability, coastal rice prairies are identified as critical spring migration stopover sites.

Use of rice fields as complementary habitats to waterbird species was investigated. Three questions were posed (1) does waterbird richness (defined as number of species), abundance and composition differ between rice fields and natural wetlands; (2) do richness, abundance and composition of waterbird species differ between flooded and drained rice fields in the post-harvest season, and (3) do richness, abundance and composition of waterbird species change in rice fields over the rice cultivation cycle? Eight collections were made in eight rice fields with different hydrological conditions after cultivation (four dry and four flooded) and four natural wetlands. Waterbirds were censused using binoculars and one telescope. A total of 76 waterbird species were observed during the study period (2005–2006): 59 species in rice fields and 70 species in natural wetlands. The richness of waterbirds was higher in natural wetlands than flooded and drained rice fields; however, there was no difference between flooded and drained rice fields. The richness of waterbirds did not change over the rice cultivation cycle. Waterbird abundance was higher in natural wetlands than in flooded and drained rice fields. Natural wetlands showed a seasonal pattern of species composition and abundance different from rice fields. Rice fields are used for an important fraction of the waterbird richness in southern Brazil, acting as habitat complementary for biodiversity, but in lower richness and abundance when compared to natural wetlands. The non-intentional flooding of rice fields did not contribute towards waterbird conservation in southern Brazil.

Wading birds have been observed foraging in agricultural wetlands worldwide where natural wetlands have become lost, degraded, or seasonally dry, yet the ability of wading birds to satisfy daily energy requirements in agricultural wetlands has been little studied. The ability to meet daily energy requirements for Little Blue Herons (Egretta caerulea) and Great Egrets (Ardea alba) foraging in flooded rice and fallow fields of the Everglades Agricultural Area (EAA) was evaluated during April-June 2008 and 2009. Focal samples were used to measure capture rates (captures/min), identify prey and estimate captured prey size, and calculate energy budgets for both species. Within flooded fields prey density was measured and foraging sites and random locations were compared. Habitat variables did not differ between foraging sites and random locations. Vegetation cover and prey abundance increased in rice fields over time and were greater in rice than fallow fields. Small prey, dominated by fish, were captured by both species and corresponded to prey sampled. Most wading birds in June were observed in newly flooded fallow fields despite lower prey densities. Little Blue Herons met daily energy requirements for both years; but Great Egrets did not, likely due to predominantly small prey, increasing vegetative cover in rice fields, and lower prey densities in newly flooded fallow fields. Although Great Egrets did not meet daily caloric requirements, the EAA may still function as an important transitional habitat at a time when foraging resources in the region are limited.

To better understand how birds balance the demands of reproduction and food-provisioning, Snowy Egrets (Egretta thula) were studied from May-July 2009 and 2010 in a mixed-species colony in Wichita, Kansas. Observations included 68 h of scan samples at 34 nests which yielded >11,000 instantaneous records; the durations of 57 food-provisioning trips made by eight radio-tagged birds; 73 records of foraging locations, and 27 h of foraging activity and aggressive intraspecific interactions. Adult activities at the nest included sitting (41% of the time), standing (18%), preening (10%), nest maintenance (7%) and feeding chicks (<1%). Incubating adults spent significantly more time sitting but less time standing than did adults with chicks. The amount of time that both parents were away from the nest increased significantly with chick age. Multiple regression analysis with AIC modeling showed that Julian date, chick stage, and year were important predictor variables in nest activity patterns. Mean food-provisioning intervals (242 ±22 min; range = 52-539 min) differed among radio-tagged birds, but did not differ by time of day or date. Round-trip flight distances averaged 16.1 ±3.2 km (range = 6-49 km), and also differed among birds. Distances to foraging sites were combined with published energetic values to estimate flight costs. Compared with birds that used distant foraging sites (>18 km from the colony), birds that used sites near the colony (<3 km) had higher capture efficiencies but caught smaller prey, had much higher rates of aggression, and lower rates of energy intake.

The diets of four seabird species (N = 20–21 individuals per species) were compared to determine whether sexual size dimorphism is involved in intersexual differences in diet composition and niche size. Diet compositions of Black-legged Kittiwake (Rissa tridactyla), Herring Gull (Larus argentatus), Great Black-backed Gull (Larus marinus) and Razorbill (Alca tarda) were assessed during their breeding season in the Gulf of St. Lawrence, Canada by using: Bayesian mixing models using stable carbon and nitrogen isotope analysis on the red blood cells of adults and direct field assessments of food items carried by adults to chicks. A total of 50 regurgitations for kittiwakes, 40 regurgitations and 76 pellets for gulls (two species combined) and 78 prey loads for Razorbills were characterized. Diet composition varied widely among seabird species and between methods of assessment. Isotopic niche size of adults was greater for males than for females for species with clear dimorphism (Herring Gull and Great Black-backed Gull), whereas differences in niche size between sexes became insignificant when sexual size dimorphism decreased (Black-legged Kittiwake). Conversely, for the monomorphic Razorbill, females displayed a larger isotopic variance than males, suggesting that factors other than body size are involved in shaping niche size.

The diet of breeding European Shag (Phalacrocamx aristotelis) was studied at Sklinna, one of the world's largest colonies, during 2007–2010. Regurgitated pellets were collected regularly throughout the chick rearing period and hard parts used to identify prey items to the lowest possible taxonomic level. The length and width of otoliths were used to estimate fish body length and mass. Shags' diet was varied and contained at least 17 different species of fish. Gadoid species, including saithe (Pollachius virens), cod (Gadus morhua) and Poor Cod (Trisopterus minutus), were the main prey and contributed approximately 90% of the diet during the study period. Saithe dominated the diet by numerical frequency, biomass and frequency of occurrence in all study years. Sandeels (Ammodytidae) contributed little to shag diet. The numerical frequency and percentage saithe biomass was lower in 2010 than in the other years. However, this was compensated by a higher frequency of cod and poor cod, making the total biomass of gadoids equal to previous years. The total biomass of gadoids caught by the shags at this colony was estimated at 340 metric tons, of which 266 tons were of 0–2 group saithe. The amount represents 0.1% of the total quota (by weight) for the fisheries and might, thus, be of minor importance for the fisheries. However, the estimated 30 million individuals represent 17% of the total number of individuals that was estimated to be recruited to the population as 3-year-old saithe in 2007–2010.

The hypothesis that the egg production capacity of northeast Pacific seabirds is reduced in years with higher spring sea-surface temperatures was tested with data collected on Glaucous-winged Gulls breeding on Triangle Island, British Columbia, Canada, from 2002 to 2011. The mean clutch size varied from 2.3 to 2.9 eggs nest-¹, but contrary to prediction, there was little relationship between clutch size and ocean temperature. In contrast, the mean egg size increased with temperature (opposite to the predicted decrease), but that effect was modest in size and limited to clutches of one and three eggs. The within-clutch variation in egg size differed little from year to year, and was unrelated to temperature. The results suggest that higher sea-surface temperatures do not compromise egg production in Glaucous-winged Gulls, a situation unlike that for some other species of marine birds on Triangle Island Received 6 December 2011, accepted 18 February 2012.

Plumage dimorphism is common in the family Ardeidae with one morph possessing all-white plumage and the alternate morph being darkly colored. The effects of plumage morph and colony site on nest initiation date, clutch size and total nest success of the plumage dimorphic Reddish Egret in the Laguna Madre region of Texas were examined. Color morph did not significantly affect nest initiation date (Julian date - Dark morph: 109.88 (S.D. 26.56), White morph: 100.82 (25.85), Mixed-morph: 113.29 (27.55); ANOVA: F_(2,158)= 0.199, P = 0.820) although nest initiation date was different between nesting colonies (Julian date - Rabbit Island: 125.14 (S.D. 18.05); Zigzag Island: 87.15 (19.07); ANOVA: F_(1,158) = 5.732, P = 0.018). Overall mean (±S.E.) clutch size was 3.29 ± 0.05 and differed between colony sites but not between color morphs. Model selection analysis using logistic exposure revealed that neither plumage morph nor colony site had a significant effect on nest success. Mayfield total nest success was estimated at 85.10% ± 5.4% (n = 171), results which are similar to nesting success estimates in other heron species. The lack of effect of color morph on timing of nest initiation, clutch size and nest success suggests other factors may influence the maintenance of color dimorphism in Reddish Egrets.

To assist long-term protection of roost sites, roosting patterns of California Brown Pelicans (Pelecanus occidentalis californicus) at San Nicolas Island (SNI), California, were assessed for the 1972–2006 period. SNI was used for roosting year-round, with most birds likely from nearest primary breeding colonies (Santa Barbara and Anacapa islands) within the Southern California Bight subpopulation. Among non-El Niño years, monthly diurnal counts varied, but ranged from less than 100 birds during the breeding season to approximately 1,000 during fall. Influxes from the large Gulf of California subpopulation also occurred on occasion, best demonstrated by prolonged increased numbers during strong El Niño conditions in 1972–1973, possibly reflecting delayed or skipped breeding and increased prey availability near the outer California Channel Islands. The peak estimate of 13,500 night-roosting pelicans was on 16 November 1972 during these El Niño conditions. Most pelicans roosted diurnally on the north shore, reflecting close proximity to main foraging areas. Diurnal roost patterns did not appear affected by introduced feral cats (Felis catus) and Island Foxes (Urocyon littoralis dickeyi). The single, major night roost shifted 4 km from Cormorant Rock Area (used 1972–1992) to Vizcaino Point by 2006, following reduction of human disturbance in 1992–1996. Vizcaino Point and Cormorant Rock Area should be designated as “key, long-term roosts” that merit additional protection. Received 25 July 2011, accepted 14 March 2012.

Quantitative, comparative studies are needed to better orient conservation efforts for the endemic, threatened avifauna of the Bogotá wetlands. The influence of landscape and local factors on abundance was studied for seven species: Bogotá Rail (Rallus semiplumbeus) and Apolinar's Wren (Cistothorus apolinari), endemic species; Ruddy Duck (Oxyura jamaicensis), Spot-flanked Gallinule (Gallinula melanops), American Coot (Fulica americana) and Yellow-hooded Blackbird (Chrysomus icterocephalus) with endemic subspecies; and the widespread Common Gallinule (Gallinula galeata). Areas, habitats and landscapes of nine urban and ten rural wetlands were quantified using GIS and remote sensor images; water quality and abundances of feral dogs and Shiny Cowbirds (Molothrus bonariensis) were evaluated in adjunct studies. Populations of focal species were estimated by point counts. Wetland variables were analyzed with principal component, canonical correlation and redundancy analyses and related to bird abundances and densities by multiple regressions. Most urban wetlands were covered by aquatic vegetation; rural wetlands were mostly open water with less vegetation. Abundances of all focal species increased with wetland area. Abundances of the endemic rail, wren and blackbird were correlated with emergent vegetation area and/ or negatively with open water, whereas duck, coot and gallinule abundances were correlated with open water area and/or negatively with urbanized landscapes, therefore both urban and rural wetlands are necessary for conservation of this endemic avifauna. Public investment has favored only some urban wetlands hence a regional, rather than local, approach to wetland management is needed. The situation of the wren is especially critical, probably due to brood parasitism by the cowbird.

The range and natural history of Neotropical rails are little understood. Observations are presented on the range, diet and breeding of seven poorly known rails amassed during 15 years of intensive fieldwork in Brazil and visits to dozens of ornithological collections: Amaurolimnas concolor, Neocrex erythrops, Micropygia schomburgkii, Gallinula melanops, Parphyrio flavirostris, Lateiallus exilis and Pardirallus macidatus. The proposed disjunctions in some species ranges between the humid forests of Central America/northern South America and those in eastern Brazil are an artifact due to the natural scarcity of some species in the drier formations of central South America as well as to incomplete sampling.

A difficulty in the study of monomorphic species is the inability of observers to visually distinguish females from males. Based on a sample of 745 known-sex birds nesting at Bird Island, MA, USA, a discriminant function analysis (DFA) was used to sex Roseate Terns (Sterna dougallii) of the Northwest Atlantic population using morphological measurements. DFA using only the total length of the head (including the bill) correctly identified the sex of approximately 86% of the terns, which increased to 88% if both members of a pair were measured. Including additional measurements increased these percentages slightly, to 87% and 90%, respectively. These levels of accuracy are generally higher than those reported for other species of terns. Because female-female pairs are frequent in this population, one cannot assume that the member of a pair with the larger head is a male, and additional discriminant functions were developed to help separate female-female from male-female pairs.

Maintaining appropriate developmental temperatures during avian incubation is costly to the parents, so embryos may experience pronounced variations in temperature that can lead to embryo mortality and extended incubation periods, or that could affect the offspring phenotype in several bird species. The egg temperatures (N = 28 eggs) of free-living Magellanic Penguins (Spheniscus magellanicus) were recorded in a breeding colony in Puerto Deseado, Santa Cruz, Argentina. Three nests had atypical incubation patterns. Two nests experienced high temperature drops (average = 11.7^°C, minimum = 6.5°C, duration = 9 h) and another nest had a broad daily temperature range (max-min), i.e. 13.9 ±0.9^°C for the first egg and 14.1 ±0.8^°C for the second egg (range = 8-22°C during egg laying and 18–37°C during advanced incubation). Thermal anomalies during incubation did not affect the embryonic viability, hatchling mass or fledging success. The survival of embryos despite these atypical incubation patterns may be an adaptive mechanism during the harsh weather conditions normally experienced by eggs throughout incubation.

Little is known about the intestinal microflora of Common Terns (Sterna hirundo) and their capacity to disseminate human gastrointestinal pathogens along migratory flyways. Common Tern chicks on Pettit Island in Barnegat Bay, New Jersey, USA, were evaluated for carriage of bacterial and protozoan pathogens. Oropharyngeal and cloacal swabs were taken for culture-based detection of bacterial gastrointestinal pathogens during the 2009 and 2010 breeding seasons. Bulk fecal samples were also taken during the 2010 nesting season to determine Cryptosporidium oocyst loads. Of 125 birds sampled in 2009, none carried Salmonella and only one carried Campylobacter. Moreover, the majority of birds sampled in the 2009 breeding season carried Escherichia coli and Klebsiella ozaenae, members of bacterial family Enterobacteriaceae. In 2010, one of the 54 birds sampled carried Salmonella and none had Campylobacter in their intestines. Similar to the birds sampled in 2009, the 2010 cohort showed relatively high carriage of E. coli and K. ozaenae. Microscopic examination of fecal smears obtained in 2010 revealed that 39 of 54 Common Tern chicks had microscopic structures consistent with Cryptosporidium oocysts in their intestines. These data indicate that Common Tern chicks in Barnegat Bay present low to no threat to public health through the spread of human gastrointestinal pathogens.