The largest breeding colony of the endangered California Least Tern (Sterna antillarum browni) north of San Luis Obispo County occurs at Alameda Point, San Francisco Bay, California. Data on population size, reproductive success, and food habits were collected since the colony’s inception in 1976, while more specific data on breeding chronology (dates of active nesting and nest initiation dates), clutch size, hatching success, and size of prey dropped at the breeding site were collected from 2000-2004. The number of breeding pairs increased by 10.4% per year, making this colony the largest colony in San Francisco Bay and representing 6% of the state population. Breeding success varied but is generally superior to the state’s combined productivity numbers. Of the 32 Least Tern sites monitored in 2004, only five other colonies had higher breeding success than Alameda Point in that year. Despite the colony’s success, both hatching and breeding success have declined since the mid-1990s. Terns at this urban location forage in central and south San Francisco Bay, characterized by both marine and estuarine water. Dropped prey collected since 1981 indicate that silversides (family Atherinopsidae) were the most abundant prey in all years. Breeding success was positively correlated with the proportion of Northern Anchovy (Engraulis mordax, family Engraulididae), the second most common prey collected, suggesting that this high-energy fish may be beneficial to these terns. Potential factors limiting growth of this crucial northern Least Tern colony include predation and human disturbance, an inadequate protected nesting area, and environmental variability and its effects on prey abundance.

We recorded and compared diurnal and nocturnal time-activity budgets of American Avocet (Recurvirostra americana), Lesser Yellowlegs (Tringa flavipes), Least Sandpiper (Calidris minutilla), and Wilson’s Phalarope (Phalaropus tricolor) on 21 saline lakes in the Southern Great Plains, USA, during spring and summer/fall 2002 and 2003 to examine importance of saline lakes as migratory stopover sites. All four species spent most of their time feeding (47-70%) and resting (7-37%) by day and at night during spring and fall migrations. Little time was spent in other behaviors. Time budgets differed among species and between seasons, likely due to different energy needs. Time spent foraging varied seasonally between saline lakes and freshwater playas for American Avocets and Least Sandpipers, likely due to differences in vegetation cover and availability of prey between these wetland types. For most species, time spent foraging and resting differed between day and night. Therefore, extrapolating diurnal activity budgets to the entire 24-hour period and from one type of habitat to another within the same region is not recommended. Saline lakes are used by migrant shorebirds as stopover sites where they replenish lipid stores. Conservation efforts should focus on preserving these unique wetlands and the freshwater springs that discharge in them.

The Gulf of Panama is a highly productive marine ecosystem at the southern edge of North America. Although the Gulf’s aquatic bird populations have been remarked upon by ornithologists for over 50 years, nesting populations have been neither systematically studied nor completely characterized. In 2005 and 2006, the entire Gulf of Panama was inventoried to document the nesting status of seabirds and other colonial waterbirds. Over 50,000 birds of 20 species nesting at 57 sites were documented. Seabirds nested during the dry season, the period of oceanographic upwelling. Coastal colonial waterbirds nested at the end of the dry season and in the early wet season, when inland feeding habitats were optimal. Brown Pelicans (Pelecanus occidentalis) were the most numerous seabird with over 4,800 nests and 10,000 individuals counted. Over 3,600 Neotropic Cormorant (Phalacrocorax brasilianus) nests and over 2,200 Magnificent Frigatebird (Fregata magnificens) nests were documented. Cattle Egrets (Bubulcus ibis) were the most abundant colonial wading birds, followed by Great Egrets (Ardea alba). Great Egrets were the first wading birds to nest, Cattle Egrets the last. Seven sites contained over 1,000 nests. Colony locations and numbers differed markedly from the historic literature. Some historic information is erroneous, but other differences reflect changes in distribution. More nesting Brown Pelicans and Sooty Terns (Sterna fuscata) and fewer Neotropic Cormorants were found than expected from the literature. New sites documented included some of global or regional conservation importance. This paper presents the first breeding records for Panama of Little Blue Heron (Egretta caerulea), Glossy Ibis (Plegadis falcinellus), and Bridled Tern (Sterna anaethetus), and third record for Cocoi Heron (Ardea cocoi). There is no evidence for long-term declines of seabirds or colonial wading birds in the Gulf of Panama. Populations reaching conservation thresholds globally or biogeographically include Brown Pelican, Bare-throated Tiger-Heron (Tigrisoma mexicanum), White Ibis (Eudocimus albus), Glossy Ibis, and Bridled Tern. The Black-crowned Night-Heron (Nycticorax nycticorax) exceeded conservation thresholds for Central America. Six new sites of global importance for bird conservation were identified and the continued importance of another site confirmed. The continued health of the waterbird populations of Panama will depend on environmental education and protection of important colony sites from disturbance and development.

During the 2003 breeding season 367 historic, potential, and current nesting sites of larids (Fam. Laridae) along the coast of western Mexico were surveyed. In 2004 and 2005, three areas: Guerrero Negro, in Baja California Sur; Marismas Nacionales, in Nayarit-Sinaloa; and Laguna Cuyutlán, in Colima were surveyed more intensively. In 2003-2005, there were nine nesting sites and probably between 200 and 300 breeding pairs of Caspian Tern (Sterna caspia); eleven confirmed nesting sites and at least 13,000 breeding pairs of Royal Tern (S. maxima); two nesting sites, one of which included almost the entire population, and 90,000 breeding pairs of Elegant Tern (S. elegans); four nesting sites and about 20 breeding pairs of Forster’s Tern (S. forsteri); and 13 nesting sites and about 1,000 breeding pairs of Black Skimmer (Rynchops niger). Breeding of Caspian and Elegant Terns on the Pacific coast of Mexico is confined to the northern areas, whereas that of Royal Terns and Black Skimmers occurs at selected sites along most of the coast. Forster’s Terns nest in two widely separated areas, one in the northern section of the coast, and one in the southern section.

Environmental acidification has been associated with factors that may negatively affect reproduction in many waterbirds. Declines in lake pH can lead to reductions in food availability and quality, or result in the altered availability of toxic metals, such as mercury. A recent laboratory study conducted by the U.S. Geological Survey and the Wisconsin Department of Natural Resources indicated that Common Loon (Gavia immer) chicks hatched from eggs collected on acidic lakes in northern Wisconsin may be less responsive to stimuli and exhibit reduced growth compared to chicks from neutral-pH lakes. Here we report on the relation between Common Loon egg characteristics (eggshell thickness and egg volume) and lake pH, as well as eggshell methylmercury content. Eggs (N = 84) and lake pH measurements were obtained from a four county region of northern Wisconsin. Eggshells were 3-4% thinner on lakes with pH ≤ 6.3 than on neutral-pH lakes and this relation was linear across the pH range investigated (P < 0.05). Egg volume also tended to be larger in eggs from neutral-pH lakes. Eggshell methylmercury content however was not significantly related to shell thickness (P > 0.05, n.s.) or lake pH. Results suggest that low lake pH may be associated with thinner eggshells and reduced egg volume in Common Loons. We speculate on the mechanisms that may lead to this phenomenon.

For most ground-nesting seabirds, offshore islands usually serve as refuges from mammalian predators, however, introduced predators pose a substantial threat to many species. In New England, thousands of Herring Gulls (Larus argentatus) and Great Black-backed Gulls (L. marinus) breed on hundreds of coastal islands. The Isles of Shoals (New Hampshire/Maine) archipelago has some of the largest colonies of both gull species in New England. In 2004, we noted unusually large numbers of failed nests on Appledore Island, Maine and hypothesized that Raccoons (Procyon lotor) were the cause. Therefore, we quantified egg and chick mortality and documented the presence of Raccoons. We trapped Raccoons on Appledore and Smuttynose islands and conducted nest surveys on these and two other islands in the Isles of Shoals. Surveys of marked nests on Appledore Island revealed high levels of egg and chick mortality in early June 2004; by late June 58% of nests were empty. We also found that on Appledore and Smuttynose, where Raccoons were observed, the odds that a nest would be empty were 17 times greater than on Lunging or Duck Islands where no Raccoons were observed. During 2004, eleven Raccoons were trapped off of Appledore and Smuttynose Islands. A survey of nests in 2005 showed that gull breeding success increased significantly on Appledore and Smuttynose islands, whereas there was no significant change in the relatively high ratio of chicks to nests from 2004 to 2005 on Lunging Island where Raccoons were not observed. Thus, we concluded that the presence of a few Raccoons on Appledore and Smuttynose islands was sufficient to cause substantial breeding failure in large colonies of larids.

Foraging habitat selection of nesting Great Egrets (Ardea alba) and Snowy Egrets (Egretta thula) was investigated within an estuary with extensive impounded salt marsh habitat. Using a geographic information system, available habitat was partitioned into concentric bands at five, ten, and 15 km radius from nesting colonies to assess the relative effects of habitat composition and distance on habitat selection. Snowy Egrets were more likely than Great Egrets to depart colonies and travel to foraging sites in groups, but both species usually arrived at sites that were occupied by other wading birds. Mean flight distances were 6.2 km (SE = 0.4, N = 28, range 1.8-10.7 km) for Great Egrets and 4.7 km (SE = 0.48, N = 31, range 0.7-12.5 km) for Snowy Egrets. At the broadest spatial scale both species used impounded (mostly salt marsh) and estuarine edge habitat more than expected based on availability while avoiding unimpounded (mostly fresh water wetland) habitat. At more local scales habitat use matched availability. Interpretation of habitat preference differed with the types of habitat that were included and the maximum distance that habitat was considered available. These results illustrate that caution is needed when interpreting the results of habitat preference studies when individuals are constrained in their choice of habitats, such as for central place foragers.

The Illinois and central Mississippi river valleys provide important habitats for migrating waterfowl. Unfortunately, both river systems have experienced large-scale hydrologic alterations, resulting in considerable loss of waterfowl habitat. To provide information to guide wetland conservation and rehabilitation efforts, we used data from aerial inventories of waterfowl conducted by the Illinois Natural History Survey to model Mallard (Anas platyrhynchos) use in relation to wetland characteristics. Mallard use was positively associated with the proportion of wetland area classified as “emergent” (e.g., containing robust or moist-soil wetland vegetation) during spring and fall in both river valleys. Use by Mallards was also related to proportion of inventoried locations where hunting and other disturbances were prohibited during fall and spring, perhaps indicating better management of fall refuges to provide foraging habitat during spring. We suggest wetland habitat acquisition and rehabilitation efforts intended to benefit waterfowl emphasize emergent-wetland components. Further, we recommend investigations of wetland use by waterfowl in each river system to elucidate the role of areas where hunting and disturbance is prohibited.

In the first comprehensive survey of tern colonies in the Honduras Bay Islands, 46 cays were surveyed in 2005 and 2006 and three species of terns were observed nesting in colonies on ten individual cays. Apparent colony turnover was high between years for Least (Sternula antillarum) and Roseate (Sterna dougallii) Terns, from 71% to 100%, respectively. The first nest records of Bridled Tern (Onychoprion anaethetus) for Honduras are documented.

In this study we present data about local distribution, abundance, and habitat preferences of Black-headed Duck (Heteronetta atricapilla) in central Chile. Black-headed Duck is an endemic species of southern South America and the only obligate brood parasite whose ducklings needs no further parental care after incubation of the eggs. From July 1993 to January 1998 we monitored populations in 19 wetlands of the Mediterranean distribution is restricted and its presence is strongly associated to habitat with emergent vegetation. These results suggest that, populations located on the occidental side of the Andean highland, would present ecological traits strongly associated with rarity and high vulnerability.

Little is known about the factors influencing the breeding decisions of Arctic breeding seabirds and their behavior in a failed breeding year. Here we present the behavioral patterns observed in a year with late sea ice break-up and regular predator visits to the colony. We found that breeding initiation of Arctic Terns and Sabine’s gulls was delayed until the breeding attempt was given up and the colony abandoned. However, the birds did not leave the region but returned to the colony soon after sea ice break-up continuing bonding behavior although egg-laying was not initiated. In 2006, the period 11-15 July seemed important for the breeding decision, as birds gradually gave up breeding and left the colony during that period.

Dovekie (Alle alle) parents feed their chicks almost exclusively with high energy Arctic zooplankton associated with cold polar waters. In years with a stronger influx of warm Atlantic waters (positive NAO index) in their traditional feeding grounds, they may be forced to forage in suboptimal feeding areas. We compared the Dovekie chick diet in Hornsund (Spitsbergen) in the early, mid and late phases of the chick-rearing period in two seasons with different distributions of cold (Arctic) and warm (Atlantic) water masses. Parents delivered to their chicks food loads of lower wet weight (in the mid and late phase) and lower energetic value (in the late phase) under warm water conditions compared to colder water conditions. This suggests worse foraging conditions for Dovekies and foraging in suboptimal feeding areas during warm water events. However, data from the mid phase showed that Dovekies are able to compensate by increasing the number of daily feedings. In this phase, chicks received the same amount of food (by mass and energy) as in cold years. It is unknown how large the inflow of Atlantic water can be before it has negative implications for adult Dovekie daily time budget, body condition, survival rate, their breeding success and fitness.

Helicopter spraying of rotenone fish poison over Paardevlei, a lake near Cape Town, provided an opportunity to assess both the effect of helicopter disturbance on waterbirds and the immediate response of birds to fish poisoning. Birds were less disturbed by protracted helicopter activity than by a single fish eagle over-flight. Rotenone provided a food bonanza for pelicans and cormorants with no evidence of adverse effects on any birds.

American Black Ducks (Anas rubripes) molt some tertials and tertial coverts during their first fall and winter, but descriptions are incongruous and the timing, extent and sex-specific differences in molt patterns are largely unknown. We studied molt of these feathers from fall to spring using captive, harvested, and trapped wild birds, as well as specimen wings. During their first fall and winter, males molted earlier and replaced more tertials and tertial coverts than females, but all birds retained some juvenile tertial coverts until the end of April. We attribute these differences to their primary mating system of annual monogamy, with females being the limiting sex. The early acquisition of adult tertials and tertial coverts are likely selectively advantageous for males because these feathers are prominently displayed during courtship and pair bond formation. Young birds that have acquired adult-like feathers may exhibit a higher degree of fitness, facilitating breeding in the first year. This knowledge of wing feather replacement is useful for determining the age of Black Ducks as either second year or after second year and can also be used in dual feather isotope analysis to link natal and wintering areas.

Waterbird surveys following the annual African Waterbird Census were conducted in the Antsalova region of western Madagascar from 2002 to 2004. Seven wetland sites were monitored: five freshwater lakes, one alkaline lake and one marsh. Three of the five fresh water lakes were in the Manambolomaty Lakes Complex, a RAMSAR site. A total of 37,836 individual birds were recorded belonging to 55 species representing 15 families. The marsh had the highest waterbird abundance of all sites with an average of 3,616.3 ± 461 individuals (N = 3 years). Species diversity index was highest in the freshwater lakes with an average of 2.53 ± 0.07, and the lowest was recorded at Antsohale Lake with an average of 2.22 ± 0.08. The waterbird abundance varied significantly between freshwater lakes and the marsh from 2002 to 2004, between freshwater lakes and the alkaline lake in 2003 and 2004, and between the alkaline lake and marsh. The net difference in species abundance between the Manambolomaty Lakes Complex and the other lakes varied significantly. In contrast, species richness between the Manambolomaty Lakes Complex and the other lakes did not vary. Several threatened species were at population levels observed ten years earlier.

Winter observations of Black Terns (Chlidonias niger) in Mexico are rare. On 19 January 2007, we observed over 3,000 Black Terns foraging among hundreds of breaching manta rays one kilometer offshore on the coast of Guerrero, Mexico.

Adult Greater Flamingos (Phoenicopterus roseus) are sexually dimorphic, with males being on average larger and heavier than females. However, there is no practical way to sex the chicks by their morphology. Here we describe a method relying on quick and easy DNA extraction from feathers. A PCR test employing primers to amplify introns whose lengths usually differ between the CHD-W and the CHD-Z genes allow sex discrimination. This method is thus a fast, accurate and inexpensive protocol to sex flamingo chicks from feathers bulbs sampled in the field.