The applicability of color infrared photography to indirectly predict prey abundance for shorebirds was tested by measuring the chlorophyll concentrations of primary producers on the mudflat surface at eleven migratory stopover sites of shorebirds in Georgia Strait, British Columbia during southward migration in July and August 2002. Many shorebirds are associated with regions of high coastal zone productivity, which may contribute to high prey abundance. Chlorophyll levels of primary producers contribute to the red tones of an infrared photograph. The hue of an infrared photograph was positively related to the chlorophyll concentration of the sediment surface across all sites. However, invertebrate density was not strongly related to surficial sediment chlorophyll concentration or photograph hue. The color infrared photography method is useful to quickly assess the surficial sediment concentration of the phytobenthos, but of low value to estimate invertebrate prey densities.

A monthly shorebird census in Mondego estuary, Portugal was made during ten years (1993-2002) and the information adds to the midwinter census carried out at international level. It is shown that higher variability in shorebird community occurred during the breeding and migrating periods, while the winter assemblage was very similar among years. The study provides precise information of the importance of the Mondego estuary, and the trends and phenology of its shorebird community. Six species are responsible for a large proportion of the total abundance throughout the year. Dunlin (Calidris alpina) is the most abundant species, followed by the Avocet (Recurvirostra avosetta). Over the study period, there was a significant increase in the total number of shorebirds that occur in some months. This was mainly due to the increase of the main species, the Dunlin. Only the Avocet showed a significant decrease in abundance. These trends were not explained by changes in overall flyway population or the Portuguese totals. Therefore, local explanations need to be considered (e.g., changes on habitat quality).

Feeding Black-faced Spoonbills (Platalea minor) were studied in four main areas along the coasts of South Korea, Taiwan, China and Vietnam. They fed on nekton, mainly fish and shrimps, varying in length between 2-21 cm that were caught by sweeping the bill in the water. The feeding behavior of a spoonbill is a chain of feeding and inter-feeding bouts. Each feeding bout started by putting the bill into the water and ended when the bill was taken out and any prey captured was swallowed. The times between feeding bouts were short and no or few steps were made. In a complete feeding bout, up to three functional phases were distinguished. These were successively (1) the attempt to locate a prey, (2) the attempt to catch the located prey, (3) the handling and swallowing of the prey. A feeding bout could end in any phase. A total of 1,684 feeding bouts were recorded of which 65% ended with swallowing prey. The mean outcome was 45.4 small (<5 cm long) and 1.3 large (>5 cm long) prey per 10 min. Tentative measurements indicated that a feeding spoonbill walked on average 3.87 m per 10 s, during which time the bill made 15.7 sweeps with a bill velocity of 5.8 km.h^-1, meanwhile testing about 17% of the area within reach of their bill for the presence of food. Feeding by Black-faced Spoonbills often looked chaotic because they usually walk all over the feeding site at a variable speed, while showing a large variety of actions especially when large prey is present. However, analyses of the observations show that they behave efficiently and reduce time and energy spent in feeding in several ways, including giving-up times not much longer than the duration of bouts with success, pursuing only large prey, ceasing feeding and starting to rest or going to another site when no prey is caught in 5-10 min. With their tactile way of feeding on invisible prey, they also behaved efficiently by consuming all detected prey that could be caught and swallowed.

The foraging behavior of adult and recently fledged juvenile Squacco Herons (Ardeola ralloides) was studied during the breeding season at the Axios Delta, northern Greece. Adults were more efficient foragers than young birds and they had a 37% higher success per peck rate. The majority of adults captured some large prey items, while most juveniles caught only small prey. A comparison between the two age classes, as well as seasonal trends in adult data, indicated a negative association between prey size and foraging rates. Adult and juvenile foraging behavior did not vary significantly between morning and evening. Herons that moved faster also had higher pecking and capture rates, but a lower success ratio. Moving rate did not appear to be correlated with prey size. Herons moved at a slower rate along the edge of dense reed beds, probably in response to this habitat’s physical structure. Adults caught a greater proportion large prey items in open-water areas than in areas with more vegetation.

The food composition, prey size, quantity of prey, feeding frequency and diurnal pattern in the feeding frequency of chicks of Black Stork (Ciconia nigra) were studied in six nests in the Czech Republic during the breeding seasons 1998-2003. Video cameras were used to record prey brought to the nests. Regurgitations and pellets were also analyzed. In total, 474 prey items were collected. Aquatic animals, mainly fish, prevailed in the nestlings’ diet. Six species of fish, undetermined frogs and snakes, two mammal species and eight insect species were found. Adults provisioned their young nestlings with smaller fish. The length of fish and total mass of consumed prey significantly increased with nestling age. No relationship between chick age and feeding rate was found. In total, each chick consumed 14-20 kg of food up to fledging.

The foraging behavior and feeding locations of the Red-legged Cormorant (Phalacrocorax gaimardi) were studied at Ria Deseado, Argentina during the last week of the incubation period in 1999. VHF radio-transmitters were deployed on six nesting adult cormorants. Red-legged Cormorants fed during the daylight hours and made 4.0 ± 0.8 trips per day, with a mean duration of 1.2 ± 0.8 h. Birds spent 27% of daylight hours away from the colony on feeding trips, diving for 96% of the foraging trip, and made a mean of 78 dives per trip. Mean foraging range was 1.9 ± 0.9 km, being the shortest of any of the Patagonian cormorant species. Red-legged Cormorants fed mainly in shallow waters <5 m deep and within one km from the shore. Most of the feeding trips were undertaken during falling tide, when the birds performed the shortest feeding trips with maximum diving rates and, probably minimized transit times and maximized searching time on the seafloor. Our results show that foraging behavior is mainly influenced by environmental factors such as the direction of the tide. Red-legged Cormorants seems able to forage by selecting the appropriated tidal conditions to minimize foraging effort.

A comparative study was made of Yellow-legged Gull (Larus michahellis) chick diet at six colonies on rocky islands off the southeast coast of France, and which had marked differences in their accessibility to landfills. We determined the type of foraging habitat used (landfill, other terrestrial habitats, marine habitat) and the number of foraging habitats that supplied the food in each regurgitate (one, two or three). Landfills were consistently used by gulls from the six colonies, but not always as the main foraging habitat (38% to 83% of regurgitates). For the four colonies off Marseilles (high landfill accessibility), the majority of regurgitates contained food from only one foraging habitat while, at two colonies with low landfill accessibility, the majority of regurgitates each contained food obtained from two foraging habitats. Moreover, the Principal Component Analysis performed on diet features and landfill accessibility parameters demonstrate a significant inverse correlation between landfill accessibility and foraging on terrestrial habitats. The results underlined the influence of landfill accessibility on the characteristics of the chick’s diet. Moreover, they also suggest that during chick rearing, adult gulls shift their diet from a high specialization on landfill foraging (brooding period), towards a more diversified diet, feeding their chicks by increasing the use of terrestrial habitats..

A double-observer approach was used during colony surveys of large gulls to estimate nest detection probabilities and unbiased estimates of abundance. Several models were developed that incorporate different assumptions about the sources of variation in detection probabilities (observer, colony, vegetation height). Nine colonies were surveyed in which a total of 137 transects were conducted. Although the most likely model was a one with a constant nest detection probability, a constrained model with observer dependent nest detection probability had substantial support. Overall detection probability (probability that a nest was detected by at least one of the two observers) was 0.943 (SE ± 0.008). Detection probability for a single observer was lower (0.761, SE ± 0.016). These estimates indicate a relatively high underestimation of the population sizes of large gull species when not taking into account nest detectability.

Regular counts of Greylag Geese (Anser anser) on the islands of Tiree and Coll, Argyll, Scotland have taken place since 1982. In the last 20 years, there has been a ten-fold increase with numbers leveling out since 2000 at ca. 4,000 geese. Breeding productivity, measured as percentage young in August flocks and brood sizes, was comparable to Greylag Geese on other Hebridean islands. Sightings of 1,002 individuals banded since 1998 were largely restricted to the islands, although six birds were recorded in other parts of northwest Scotland where re-sighting probability was low, indicating dispersal to new areas. The large difference between annual productivity and estimated mortality rates, coupled with the leveling-off of counts, suggested that moderate numbers might be emigrating. Greylag Geese fed primarily on silage fields and improved permanent pastures throughout the winter. Goslings remained with their parents until early April, when the adults moved to relatively remote, uncultivated land to breed. During the non-breeding season, the average flock size decreased from 70 to 22 birds. Winter home ranges of breeding adults and goslings were smaller than those of non-breeding adults and geese in their second winter, suggesting that social groups within flocks were out-competed from the preferred feeding areas and, as a result, may be more likely to disperse and colonize new areas. Geese showed individual and specific preferences for restricted parts of potential feeding areas. These basic elements of flock dynamics need to be understood when selecting management options. Current management, involving wide-scale shooting and scaring, requires provision of adequate feeding refuges to prevent dispersion of the grazing conflict to other areas, both within and beyond the two islands.

Radio telemetry and diurnal time activity budgets were used to show that wintering Lesser Scaup (Aythya affinis) used different habitats for comfort and feeding activities at Merritt Island National Wildlife Refuge (Merritt Island), Florida and adjacent estuarine areas. Management should take this spatial consideration into account. The same data were used to determine if habitat use differed between sexes. Data on movements and home range were used to evaluate habitat quality and potential effects of human disturbance. Scaup foraged more in impounded wetlands and rested more in open estuarine regions. Mean distance between diurnal and nocturnal sites was 2.7 km (SE ± 0.3), and was similar between sexes and from mid to late winter. Male and female fixed kernel home ranges and core use areas did not differ. Mean fixed kernel 95% home range and 50% core use areas were 15.1 km² (SE ± 2.0) and 2.7 km² (SE ± 0.5) respectively, representing 3% and 0.5% of surveyed habitats. Males and females used habitats similarly and short distances traveled between diurnal and nocturnal sites suggested that habitat conditions were similar across the impounded wetlands and shallow portions of both the Indian River and Banana River. Sedentary or short movements suggested that disturbance was probably negligible at the principal areas used by Lesser Scaup. Habitat management strategies for scaup should not be restricted to Merritt Island. Adjustments should be made to take into account that maintenance activities occur in adjacent estuarine areas as well.

A mark-recapture study was conducted on color-banded Roseate Terns (Sterna dougallii) breeding in southwestern Puerto Rico from 1991 to 1994. The initial estimate of apparent annual survival of adults was 62%. After accounting for the annual rates of color-band loss (11%) and permanent emigration (2-13%), the adjusted annual survival rate estimate for adults ranged from 71-80%. The estimate of pre-breeding survival from fledging to age three was 31% for a cohort of chicks banded in 1991. The adult survival estimate is low compared to other seabird species, but similar to estimates derived from Roseate Terns breeding in the western North Atlantic. Considered together, these survival estimates support the hypothesis that Roseate Terns experience high mortality during the non-breeding season, when the ranges of the North American and Caribbean populations overlap. If so, management of this species only during the breeding season may do little to aid its recovery.

Several hypotheses predict that nest defense should increase as the nesting cycle progresses, but the predicted pattern of increase differs. Previous studies of nest defense in gulls and terns have given conflicting results. Most of these have treated colonies as a unit, thus breeding asynchrony may have obscured temporal patterns. Common Tern (Sterna hirundo) nest defense against Great Black-backed Gulls (Larus marinus) was observed during two years, and responses of individuals or pairs of known nesting stage were recorded. Responses of terns to observers were also recorded. Mobbing of gulls did not increase as incubation progressed, contradicting parental investment models, but did increase as chicks aged. Chicks were defended more strongly by parents than were eggs. Responses to Great Black-backed Gulls were more frequent during the second wave of nesting, when the potential for re-nesting would be very low. There was no association between clutch size and nest defense. Aggression by terns to observers was rare during incubation, but became common immediately after hatching and remained frequent until the chicks fledged. The temporal pattern of mobbing in the semi-precocial Common Tern most closely resembles that predicted for species with altricial young. However, interpretation is complicated by the fact that gulls prey more frequently on chicks than eggs.

We investigated factors affecting chick provisioning by radio-tagged Caspian Terns (Sterna caspia) nesting in a large colony on East Sand Island in the Columbia River estuary during 2001. Caspian Tern predation on juvenile salmonids (Oncorhynchus spp.) in the estuary prompted resource managers to relocate ca. 9,000 pairs of terns nesting on Rice Island (river km 34) to East Sand Island (river km 8), where terns were expected to consume fewer salmonids in favor of marine forage fishes. This study investigated factors influencing foraging success, diet composition, and overall reproductive success at the managed Caspian Tern colony. Our results indicated that daytime colony attendance by nesting terns averaged 64% and decreased throughout the chick-rearing period, while duration of foraging trips averaged 47 min and increased during the same period; these seasonal changes were more strongly related to date than chick age. Average meal delivery rates to 2-chick broods (0.88 meals h^-1) were 2.6 times greater than to 1-chick broods (0.33 meals h^-1). Parents delivered more juvenile salmonids to chicks during ebb tides than flood tides, but meal delivery rates to the nest remained constant, suggesting diet composition tracks relative availability of prey species. Foraging trips resulting in delivery of juvenile salmonids averaged 68% longer than foraging trips for schooling marine forage fishes, indicating higher availability of marine prey near the colony. High availability of marine forage fish in the Columbia River estuary during 2001 was apparently responsible for high colony attendance, short foraging trips, high chick meal delivery rates, and high nesting success of Caspian Terns on East Sand Island.

The prey displayed to mates and delivered to chicks by nesting Gull-billed Tern (Sterna nilotica) was studied in a colony on a coastal lagoon in eastern Spain during 2003. During 31 hours of observations, 1,091 prey items were observed. The trophic resources exploited by the species and seasonal differences in prey composition within the same breeding season were examined. Red Swamp Crayfish (Procambarus clarkii) was the main prey species (64% of prey items), followed by insects (17%) and fish (6%). The proportion of terrestrial prey taken was low. Proportionately more aquatic prey was brought to the colony during courtship-period and chicks were fed proportionately more aquatic prey earlier in the season. The proportion of vertebrate and invertebrate prey did not change significantly during the season. The prey observed in the study suggests that the Gull-billed Terns foraged mostly in rice fields.

Censuses of six tern species were carried out in the inlet of Lagoa dos Patos, southern Brazil, and on the beaches just north (along 50 km) and south (60 km) from this site. The Common Tern (Sterna hirundo) was the commonest species between October and March, with maximum abundance in January (14,100 individuals). Abundance peak for the South American Tern (Sterna hirundinacea) took place in the austral winter, with maximum values of 1,500 birds. Trudeau’s Tern (Sterna trudeaui) and Amazon Tern (Sterna superciliaris) had similar seasonal patterns occurring during all months, with abundance peak in the non-breeding period, between January and July. The maximum number of Trudeau’s Tern was estimated to be 440 birds in April and 400 in June, and that of Amazon Tern was 210 birds in April and 230 in May. A maximum of 300 Royal Terns (Sterna maxima) were recorded in September, 280 in June and 280 in July, but the species was found in every month. The Cayenne Tern (Sterna eurygnatha) was also found every month, and the maximum number occurred in October (61 terns). All six species used the southern Brazilian coast, predominantly during the non-breeding season. Common, South American, Cayenne, and Royal Terns find their breed far north and south of the study area. Trudeau’s Tern and the Amazon Tern breed inland in southern Brazil. Only the Amazon and Royal Terns showed preference for particular beach sub-areas, and both were found in large flocks near the Lagoa dos Patos inlet, the former nearer to freshwater, and the latter associated with discharges from the artisanal fishery. Beaches are used by Common Terns as roosting sites during daylight hours, and the Lagoa dos Patos inlet is used mostly for night roosting.