Highly pathogenic avian influenza (HPAI) type A of the subtype H5N1 has recently spread widely and rapidly across Eurasia, and even to Africa, with deaths of both wild and domestic birds recorded. There are fears that it may soon spread to the Americas. Media accounts, communications from international bodies and national governments, and even some of the professional research literature attributes the spread, in part, to movements of HP strains by migratory birds. The origin of highly pathogenic strains is attributed to mutations, or to reassortment of virus genes from different host species. In this paper we review these hypotheses in light of knowledge about the ecology and evolution of avian influenza, looked at from the viewpoint of its natural reservoir - waterbirds. Our purpose here is to alert waterbird biologists that they have much to contribute to the science of this globally-important issue. New technologies have revealed that the genome of avian influenza contains much variation beyond that recognizable by classical antibody techniques, and have established avian influenza as a rapidly evolving and diversifying lineage. The extensive genetic variability in the viral genome and extensive reassortment within host species suggests that high pathogenicity could repeatedly and independently evolve from low pathogenic ancestors under appropriate selection pressures, such as those in poultry production systems. This makes infection of wild birds by HPAI lineages evolved in poultry a more likely occurrence than the reverse. The available evidence largely fits this model. We make recommendations that will help reduce the incursion of domestically-evolved avian influenza strains into wild populations of birds.

We evaluated the influence of stream geomorphology and habitat quality on brood weight, offspring growth rate, and territory length of Belted Kingfishers (Ceryle alcyon) in northwestern Vermont, USA. We gathered measurements of habitat use, fish abundance and biomass, and reproductive success at breeding territories in stream reaches of differing geomorphic and habitat conditions during spring and early summer 2002. We used model selection based on AIC_c to examine the effects of stream geomorphology, habitat quality, and fish abundance and biomass on the selected reproductive measures. Geomorphic condition emerged as the most important predictor variable for models of both brood weight and territory length. We tested two viable models during the 2003 breeding season at new, independent breeding territories and found them to be well-supported. Our results provide evidence that stream geomorphic condition plays both direct and indirect roles in the habitat use and reproduction of Belted Kingfishers, suggesting that stream and riparian management strategies focused on protecting and restoring functional morphology will have ecological benefits for riverine birds.

The Gull-billed Tern (Gelochelidon nilotica) has until recently received little conservation and management attention within North America despite a relatively low overall population size and significant declines in parts of the breeding range. This lack of attention may stem in part from the wide distribution of the species, encompassing parts of six continents, and from its tendency to nest in relatively small, scattered and often ephemeral colonies. Populations of North American subspecies are alarmingly small. The current population of the eastern subspecies aranea in the U.S. is unlikely to exceed 3,600 pairs, with over 60% of these birds occurring in Texas. The Texas population has remained generally stable, but declines of populations in Maryland (where probably extirpated), Virginia, North Carolina, Florida, and possibly Georgia give cause for concern for this subspecies. For the western subspecies vanrossemi, as few as 250 pairs nest at only two locations in the U.S., both in California. When populations in western Mexico are considered, the entire vanrossemi population numbers only 600-800 pairs. Currently the Gull-billed Tern is listed as “endangered” or “threatened” in four states, and is considered to be of management concern in five others. The breeding range of the species has contracted and shifted slightly from its known historic range in the middle Atlantic states, but otherwise occupies its historic range in the United States and has expanded slightly to coastal southern California. Some range contraction in Mexico (e.g., in Sonora) may have occurred. In eastern Mexico, historical information is almost non-existent and knowledge of current distribution and abundance is incomplete. Main threats to populations in North America include loss of natural nesting islands through beach erosion or perturbations to estuarine functions, development or modification of upland habitats near breeding areas that may be important for foraging, and disturbances to colonies by humans and feral or human-subsidized predators. This species often nests on man-made substrates suggesting it could be responsive to management of breeding sites. Key research needs include more frequent and refined population monitoring, a better understanding of demographics, metapopulation dynamics and factors limiting populations as well as refinement of subspecies’ breeding distributions and wintering ranges.

Roseate Terns (Sterna dougallii) were observed and/or netted on the coast of Bahia, Brazil in January and/or February from 1996 through 2003 as well as in November 2005. The breasts of almost all netted Roseate Terns examined were washed with pink. Analysis of breast feathers taken from birds during the breeding season indicates the pink color is carotenoid-based, with astaxanthin as a major component. Pigment concentration was low, measured in micrograms of carotenoids per gram of feather (maximum recorded 6.2 μg of carotenoids g^-1 of feathers), compared to milligram quantities in overtly red feathers in other species, and varied markedly among individuals. A pink blush apparently characterizes the plumage of the Roseate Tern for most of the year, often being more prominent in January/February during the non-breeding season than in breeding birds in May.

The Atlantic coast population of the American Oystercatcher (Haematopus palliates) has seen mixed success in its recovery from historic lows at the turn of the 20th century. During the mid-1980s, breeding numbers in Maryland were estimated at 50-75 pairs based on incidental observations and the results of the state’s first breeding bird atlas project. With growing national and regional concern for the species and a need for current information on its status in Maryland, the state’s first comprehensive survey of nesting oystercatchers was conducted during the 2003 breeding season. Both hatching success and fledging success were relatively high, with some breeding birds nesting in areas where they were not previously found in the state. Most oystercatchers nested on salt marsh islands, as opposed to the extensive barrier island found along Maryland’s coast. Although a similar number of birds nested in the Chesapeake Bay and Coastal Bays, nest success was significantly greater in the Chesapeake Bay. Landscape type proved to be the only variable that was significantly associated with statewide nest success, though it did not explain the differences in success between Chesapeake Bay and Coastal Bay birds. Several existing and potential threats require consideration in future studies and management of this species.

The American Oystercatcher (Haematopus palliatus) is listed as a species of high priority by the U.S. Shorebird Conservation Plan and is state-listed as rare in Georgia; however, biologists have not focused on identifying the causes of egg and hatchling losses. In 2003 and 2004, continuous video monitoring was used to document reproductive success of American Oystercatchers and identify causes of nest failure at Cumberland Island National Seashore, Georgia. The modified Mayfield method and program CONTRAST were used to determine and compare survival of eggs and nestlings. Eleven pairs made 32 nest attempts during two seasons. Nine attempts were successful, fledging 15 chicks. Daily survival of clutches was 0.973 (95% CI = 0.960-0.987) for 2003, 0.985 (95% CI = 0.974-0.995) for 2004, and 0.979 (95% CI = 0.970-0.987) for combined years. Daily survival was greater on the North End, than on the South End of the island (χ²₁ = 7.211, P = 0.007). Eighteen of 20 nest failures during the egg stage and one of eight chick losses were documented. Egg predators included raccoon (Procyon lotor, N = 9), bobcat (Lynx rufus, N = 3), and American Crow (Corvus brachyrhynchos, N = 1). A ghost crab (Ocypode quadata) preyed on one chick. Other causes of nest failure were tidal overwash (N = 1), horse trampling (N = 1), abandonment (N = 2), and human destruction (N = 1). The North End of the island has one of the highest reproductive rates reported along the Atlantic coast. Predator control may be an effective means of increasing reproductive success on the South End of the island.

A previous study of begging in Cory’s Shearwaters (Calonectris diomedea) found that chicks convey information about their body condition through the number and rate of begging calls uttered during a feeding session. Parents delivered larger meals when chicks begged more intensely. Here we test whether acoustic properties of begging calls of Cory’s Shearwaters are related to body condition of chicks, and whether parents are responsive to changes in acoustic parameters. Acoustic parameters, which were analyzed using semi-automatic call contour analysis, included the duration of calls and silent intervals, the minimum, mean and maximum frequency in a call and the number of frequency peaks within a call. We found that, in contrast to the number and rate of begging calls, acoustic parameters did not reflect chick body condition, and were not correlated with the meal size delivered by the attending adults.

The literature indicates that predation of seabirds by ciconiiform birds is limited to terns and is generally of little impact. We monitored predation of the eggs and chicks of Cape Cormorants (Phalacrocorax capensis) by Sacred Ibises (Threskiornis aethiopicus), and Gray Herons (Ardea cinerea) for 46 days over three breeding seasons at Penguin Island, Lambert’s Bay, South Africa. The ibises were observed to take at least 152 cormorant eggs and chicks and 37 heron chicks. Extrapolation of the results to the full season of availability indicates that these ciconiiform predators may take as many as 960 cormorant eggs or chicks in a season. If so, they would be the third most serious cause of mortality among the 4,800 pairs of Cape Cormorants at Penguin Island. The observed combined effect of ciconiiform predation was greater than that of the local, predatory, Khoisan Gulls (Larus (dominicanus) vetula). We document the seasonality and diel timing of predation, behavior of the predators, and the cormorants’ responses. To place our observations in context we review the global literature concerning the incidence of ciconiiform predation upon seabirds, which we consider to be under-reported, and factors affecting it. Finally we consider the effects of ciconiiform predation on seabirds at Penguin Island relative to a broader, five-year, study of the causes of seabird mortality there, and make recommendations for conservation management.

Habitat use by Chilean Flamingo (Phoenicopterus chilensis), Andean Flamingo (Phoenicoparrus andinus) and James Flamingo (Phoenicoparrus jamesi) in single-species and mixed-species flocks were studied at Laguna de Pozuelos, Argentina, by comparing the foraging pattern of each species in the presence and absence of the others. Spatial segregation among species within a flock was found. James Flamingo used the edge and the shallow foraging depth both in single-species and mixed-species flocks. Chilean Flamingo did not use the edge or the shallow depth either in single-species or mixed-species flocks, and used moderate and deep foraging depths. Andean Flamingo exhibited the most flexible foraging pattern, grouping either with Chilean Flamingo or with James Flamingo depending on which of these species predominated in the flock. Spatial difference in the feeding behavior among the three flamingo species may be principally attributed to the habitat of prey organisms. Chilean Flamingo feeds on planktonic organisms present mainly in the upper portion of the water column, and therefore this species can access a wider range of food items if foraging at deeper depths both in single-species or mixed-species flocks. The foraging pattern of James Flamingo was indicated by its main prey, benthic and aerophilic diatoms, largely found in shallow waters near the edge of the lake. Andean Flamingo feed on benthic diatoms common in the water-sediment interface of shallow and deep waters, thus favoring its grouping behavior with James or Chilean Flamingos in mixed-species flocks.

We studied the diet of Black Skimmers (Rhynchops niger) through analysis of pellets and faeces collected at Patos Lagoon estuary, southern Brazil, where non-breeding birds gather from December to August. We identified 23 prey types from twelve families of fishes, two of crustaceans, and one of squid (N = 1797 prey items). Silversides (Odonthestes argentinensis and Atherinella brasiliensis), anchovies (mainly Lycengraulis grossidens and Engraulis anchoita), and mullets (Mugil spp.) were the main components of the diet, representing 83% of number and 81% of mass of prey. Prey size ranged 9.7-212.1 mm total length and 0.01-78.1 g, with mean at 51.6 mm and 2.81 g. Considering frequency of occurrence and the relative contribution in number and mass, the Argentinean Silverside (O. argentinensis) was the most important prey in three seasons of the year. Anchovies represented 41% of ingested mass in summer. Small-sized mullets represented 30% of prey number; but showed low mass contribution (maximum of 13% in winter). Sciaenids were only important in autumn (18% of ingested mass). Otoliths were found in 53% of pellets and 55% of faeces samples, suggesting that the relative contribution of smaller-sized prey to the diet was underestimated. Composition of diet and size distribution of prey suggest that Black Skimmers fed mainly in the lower estuary, but also on the adjacent ocean beach.

The reproductive performance of a large Great Blue Heron (Ardea herodias) colony was documented and the potential effects of weather on reproductive performance was investigated. Annual surveys were conducted during the last week of May or the first week of June between 1992 and 2004 and were designed to count all fledglings and nests in and around the heronry. Mean number of fledglings per nesting attempt during the 13-year interval was 1.57 ± 0.22 fledglings (range: 1.14 to 1.87). Mean number of fledglings per successful nest during the study was 1.80 ± 0.18 fledglings (range: 1.44 to 2.06). The number of fledglings per nesting attempt was similar to other long-term studies for the species, but the productivity based on fledglings per successful nest was typically lower. Stepwise regression analysis indicated that both fledglings per nesting attempt (active nest) and fledglings per successful nest were significantly influenced by weather patterns (number of days with greater than 0.30 inches of rain and average monthly wind speed) during the month of May prior to fledgling.

The spatial distribution of avifauna was documented in Magdalena Bay, the largest coastal wetland on the Pacific coast of the Baja California peninsula. An inventory of waterbirds in the three wetland zones of Magdalena Bay-Almejas, Baja California Sur was conducted by boat. Composition, abundance, and distribution of species were determined in 12 coastal censuses conducted from February 2002 to February 2003. A total of 207,383 individuals of 80 species and 20 families were recorded. Seven listed species breed in the wetland. Only ten out of 80 species were very common, while the others were occasional along the coastline. Guilds with highest populations were pelicans and allies (54%), followed by shorebirds (23%), and gulls, terns and skimmers (14%). The highest richness of 63 species was recorded in the Santo Domingo Channel in autumn. In contrast, the highest abundance (50,082) was recorded in fall in Magdalena Bay. Migratory birds explained spatial and temporal changes in richness, while resident pelicans and allies explain abundance variations. The highest species richness was observed in mangrove zones, particularly in the Santo Domingo Channel. Therefore, this habitat together with breeding and gathering places used for other activities, should be primary targets for future management and conservation initiatives.

Agricultural landscapes provide a wide variety of avian habitats that vary seasonally. The effects of seasonal habitat changes on the habits of four large waterbird species in an agriculture-wetland mosaic are investigated in this paper. The habits of Painted Storks (Mycteria leucocephala), Asian Openbills (Anastomus oscitans), Woolly-necked Storks (Ciconia episcopus) and Black-headed Ibis (Threskiornis melanocephalus) were documented over a 15-month period in Etawah and Mainpuri districts, Uttar Pradesh, India. Monthly road transects were undertaken to determine flock sizes, density, and habitat preference of these species. Flock sizes varied significantly with season for Woolly-necked Storks and Black-headed Ibis and with habitat for Painted Storks. Flock size and density were strongly correlated in all four species. Increasing wetland size and extent of wetlands in the landscape affected flock size of Asian Openbills implying that food availability may be the most important factor affecting flocking in this species. Density differed seasonally for Woolly-necked Storks and Black-headed Ibis. Density of all four species did not vary with extent of wetlands in the landscape. Monthly densities of Black-headed Ibis were correlated to that of all the other three species. Habitat use varied widely across species and seasons. Natural wetlands but not rice fields were preferred by all four species in nearly all seasons. Irrigation canals were avoided consistently by the Black-headed Ibis and used to different extents by the other three species. Flooded agriculture fields did not compensate adequately for natural wetlands. Wetlands need to be retained in agricultural landscapes to ensure continued survival of these species.

The Relict Gull (Larus relictus) is considered vulnerable due to its declining world population. Non-breeding season ecology of this species is poorly understood. Recent observations on wintering Relict Gulls indicated that Bohai Bay, Tianjin municipality, China, is important for this species. From 2003-2005, surveys were carried out there in order to provide data on distributions, numbers and population structure of the gulls during the non-breeding season. The results show that Bohai Bay is of international importance for Relict Gulls based on the 1% Ramsar criterion. The maximum wintering flock was composed of 3,362 individuals, which is nearly one third of the world population. Proportions of the three age groups (first-year, second-year and adult) changed through the migration season. Loss of intertidal flats and human disturbance are regarded as the main threats to the gulls. Further surveys on population size, distribution and age structure should be conducted along the coasts of southern Bohai Bay and the Yellow Sea during the winter in the near future.

The coast of the Buenos Aires province, Argentina, includes a remarkable diversity of habitats and is used by more than fifteen Nearctic shorebird species during the austral summer months. We evaluated non-breeding shorebird distribution and abundance patterns along the Buenos Aires coastal zone and determined shorebird use of different coastal landscapes. Surveys were conducted in December 2000, and January and February 2001, using line-transect methods. The data were classified based on five previously defined coastal landscapes. Fifty four localities were surveyed covering 93 kilometers of coastline. A total of 44 waterbird species corresponding to 13 families were recorded. Shorebirds (Scolopacidae, Charadriidae, Haematopodidae and Recurvirostridae) accounted for approximately 45% of recorded waterbirds, including 14 nearctic species. Shorebird species recorded per locality varied from one to eleven, with 61% of the localities having one to four species. The most common were the American Oystercatcher (Haematopus palliatus), White-rumped Sandpiper (Calidris fuscicollis), Two-banded Plover (Charadrius falklandicus), American Golden-Plover (Pluvialis dominica) and the Sanderling (Calidris alba). Shorebird species richness and abundance varied significantly among coastal landscapes, with the highest values recorded in estuarine saltmarshes of Bahía Samborombón and Bahía Blanca. Among marine landscapes, the highest abundance and number of species were recorded in sandy beaches with “restinga” patches. This study confirms that shorebirds are an important component of the birdlife in the Buenos Aires coastal zone during the austral summer months, and that their distribution is not homogeneous along the coast, with species richness and abundances varying among localities depending on coastal landscapes.

Intraspecific exploitation competition as a cause for density dependent breeding success in White Stork (Ciconia ciconia) was investigated. Breeding success of 101-126 pairs of White Storks was documented between 1999 and 2004 over an area of 1026 km² and which included suboptimal foraging conditions. Pairs were classified in density groups according to the number of neighboring breeding pairs within their home range (i.e., within a radius of 1.5 km from the nest). The surface of potential feeding habitats was used as a food resource indicator and analyzed for all nests within the home range and compared among density groups. Breeding success was density dependent. Pairs breeding alone and pairs with one neighbor within the home range most frequently reared three chicks, pairs with two neighbors reared two, but pairs with three or four neighbors most frequently failed to raise a single chick. Regarding the use of organism-weighted densities expressed as the number of conspecific neighbors breeding within a pairs’ home range and foraging biology of the species, intraspecific exploitation competition was a possible cause for density dependent breeding success.

Royal Tern (Sterna maxima) chick diet at Fisherman Island National Wildlife Refuge, Virginia, was investigated in 2003 and 2004. Primary objectives were to document common prey species, annual and seasonal variation in prey selection, and seasonal variation in prey size based on average bill length in this species. Over 2200 Royal Terns bred on this island each year of the study. Single items of prey species carried in the bill by adult terns feeding their chicks were identified using 8 × 42 binoculars. A total of 11,566 and 33,646 prey items were identified during 44 and 87.5 h of systematic observations in 2003 and 2004, respectively. Terns foraged largely on anchovy (Anchoa spp.) early in the season, then switched to herrings (Clupeidae); average prey size also increased seasonally each year. Prey switching was similar to that of Royal Terns in North Carolina (but with drum as well as herring), indicating regional adaptations to forage fish availability by this species along the mid-Atlantic seaboard.

Snowy Egret (Egretta thula) kleptoparasitism of Elegant Terns (Thalasseus elegans) at a southern California breeding colony entailed piracy of fish from recently fed chicks, adults feeding chicks and adults engaged in courtship feeding.