We used satellite transmitters (platform transmitting terminals or PTTs) during 2002 and 2003 to document spring migration timing, routes, stopover sites, and nesting sites of adult female Northern Pintails (Anas acuta) from major wintering areas of the Gulf Coast (N = 20) and Playa Lakes Regions (PLR, N = 20) in Texas, and the Middle Rio Grande Valley, New Mexico (MRGV, N = 15). Some Pintails tagged in the MRGV continued movements into Mexico. Poor winter survival or PTT failure reduced sample size to 15 for PLR Pintails, 5 for Gulf Coast Pintails, and 11 for MRGV Pintails. Apparent winter survival was 66% lower for Texas Gulf Coast PTT-tagged Pintails than for those from the PLR and MRGV. Pintails from each area used different routes to their respective breeding grounds. PTT-tagged Pintails from the MRGV followed the Rio Grande Valley north to southern Colorado, before traveling on to the Dakotas and Canada or traveled northeast and joined the migration of PLR Pintails in Texas or Kansas. The latter made initial stops in Kansas, Nebraska, Colorado, or the Dakotas. Gulf Coast Pintails traveled through north-central Oklahoma or central Kansas. Pintails that had stopped first in Kansas or Nebraska tended to settle to nest in the United States. Wetland availability in the Prairie Pothole Region of the Northern Great Plains influenced nesting destinations of PTT-tagged Pintails, but individuals settled across a wide swath of northern North America. We did not detect any consistently-used spring staging areas. Therefore, negative impacts to any of the marked populations, or their wetland habitats, may have continental implications.

Assignment and quantification of breeding production areas of migratory birds is a crucial step in understanding their population dynamics and informing conservation and management decisions, especially for game birds. Sandhill Cranes (Grus canadensis) breed throughout the North American boreal, taiga, and non-forested regions of the Arctic and Siberia. Birds harvested in North America originate from these remote northern regions but conventional mark-recapture techniques cannot readily be used to answer key questions of proportionate take due to the logistical impossibility of marking young birds in an unbiased way. We used stable-hydrogen isotope analyses (δD) of feathers from 242 hatch-year (HY) and 628 after-hatch year (AHY) cranes harvested during the 2002 and 2003 hunting seasons in Saskatchewan, North Dakota, Kansas, Oklahoma, and Texas in order to provide new quantitative information regarding their geographical origins. While adult cranes originated from throughout the breeding range, south of the tree line, most birds were produced in the southeast boreal of western Ontario and/or central Manitoba and/or western Alaska. Adult birds taken in Saskatchewan, at the northern portion of the collection area, showed more northwesterly origins than birds taken at the southernmost extreme in Texas. Isotopic analysis of claws and feathers from individuals showed good correlation suggesting that claws could also be used to delineate latitude of origin, especially for AHY birds that may retain some flight feathers for more than one year. Future studies need to consider more carefully the potential contributions of southern boreal populations and if possible to develop means to distinguish isotopically those birds originating in western Alaska.

Fidelity of King Eiders (Somateria spectabilis) to breeding and wing molt sites was examined using satellite telemetry data obtained opportunistically when battery life of transmitters provided locations in a second year. Consecutive breeding locations were obtained for eleven female and 23 male King Eiders. All females exhibited breeding site fidelity by returning to sites within 15 km of first year breeding areas on the North Slope of Alaska. Breeding locations of males in a subsequent year were located on average >1000 km from their prior breeding sites and were primarily outside Alaska, on the coasts of Russia and Canada. Second-year wing molt locations were obtained for two female and six male King Eiders. Wing molt sites of males were located 6.2 ± 3.1 km apart on average in successive years, while female wing molt locations averaged almost 50 km apart. Our results demonstrate site fidelity of female King Eiders to a breeding area on the North Slope of Alaska, document the dispersal of male King Eiders between breeding seasons, and present the first evidence for wing molt site fidelity in males.

In the Camargue of southern France, declining nest success of the Little Egret (Egretta garzetta) in mixed colonies over the past three decades has been suggested to be, at least partially, explained by exclusion from high-quality nest sites by the Cattle Egret (Bubulcus ibis). The Cattle Egret has been rapidly increasing over the same time period and are well known to be aggressive at the nest. Previous studies have also shown that the success of the Little Egret is highest in the centers of colonies. The behavioral interactions and spatial patterns of nest establishment were studied within colonies of the two species. Our data suggest that the Cattle Egret was more successful at displacing the Little Egret at nest sites than the reverse. Three indicators of nest-site quality (i.e., laying date, nest density and position within the colony) were also used to test whether the proportion of Little Egret nests within different sections of a given colony was less than that of Cattle Egret nests at higher quality sites. Our results indicated that the proportion of Little Egret nests at a given site decreased with increasing site quality. Thus, the data are consistent with the hypothesis that the Cattle Egret may exclude the Little Egret from using high-quality nest sites at least in some colonies during some years.

Apparent survival of adult Herring Gulls (Larus argentatus) occupying two distinct breeding habitats within the East Bay Migratory Bird Sanctuary, on Southampton Island, Nunavut was estimated. The first group occurred on a small island where 30 pairs bred at relatively high densities sympatrically with Common Eider (Somateria mollissima), on whose eggs they feed. The larger group occurred at lower densities on a wet coastal plain on the surrounding Southampton Island mainland, where nesting birds were sparsely distributed. Program Mark was used to analyze capture-mark-resight (CMR) data obtained over six years from 62 adults captured between 1998 and 2002; 47 and 15 nesting on the island and mainland respectively. Factors in models included group and time effects on survival and reduced time effects on encounter probabilities; additional factors and interactions were not tested due to sparse data. High model selection uncertainty and wide 95% confidence intervals around model effect sizes precluded ability to draw inferences concerning the importance of group and time factors in survival. Given these results, focus was placed mainly on an estimate of annual survival (0.87 ± 0.03 SE) from the time- and group-independent model. This is the only known survival estimate produced for Herring Gull adults at the northern limit of their North American breeding range and falls within the wide range of values reported elsewhere.

Studies of the Common Loon (Gavia immer) during its breeding season on northern freshwater lakes in North America have suggested that water quality has an influence on breeding and foraging success. Less is known, however, about the effects of water quality on loon behavior during the winter, which is spent in estuarine and marine environments. In this study, we investigated the effects of water clarity and tidal stage on loon diving behavior at seven sites along a Maryland estuary. At each site, the total number of loons observed and mean dive durations of individuals were measured and compared to various measurements of water clarity, including Secchi depth and turbidity, and to tidal stage. Dive durations were positively associated with Secchi depth, which indicates that birds dove for longer periods in areas with higher water clarity. Dives were also longer during low tide in comparison to other tidal stages. No relationship was found between aspects of water clarity and the distribution of wintering loons.

DNA sequence variation from two nuclear introns and part of the mitochondrial cytochrome-b gene were used to evaluate population structure among three subspecies of Least Tern that nest in the United States (California [Sterna antillarum browni], Interior [S. a. athalassos], Eastern [S. a. antillarum]). Sequence variation was highest for nuclear intron XI (Gadp) within the glyceraldehyde-3-phosphate dehydrogenase gene. The second nuclear intron was fixed for the same allele in all subspecies. Fixation indices, F_ST and M_ST, for Gadp indicated genetic divergence between California and Interior subspecies. Estimates of nuclear gene flow were <4 individuals/generation, except between the Interior and Eastern subspecies (4 individuals/generation). Genetic indices for mitochondrial DNA did not differ among subspecies, and gene flows (reflecting female dispersal) ranged from 10 to 83 individuals/generation. Reservations are expressed about the validity of the current subspecific divisions and further research is required, including their taxonomic relationship to the Little Tern (Sterna albifrons).

The Black-faced Spoonbill (Platalea minor) is a critically endangered species. Over 50% of individuals winter regularly in Chiku Wetland on the southwestern coast of Taiwan. This study investigated the stomach contents of the Black-faced Spoonbills killed by avian botulism between December 2002 and January 2003 to identify diet of this species at the wintering site. Fourteen fish species belonging to eight families and one species of prawn were retrieved from 43 stomachs. The Shannon-Weiner index for the diet was 1.90. Estimated mean total dry weight of contents per stomach containing animal items was 23.3 g (0.1-111.7 g). Dogtooth-toxic Goby (Yongeichthys caninus) was the most abundant diet species comprising 39% of the total diet items but contributed only 2% of the estimated total dry weight. Large-scale Mullet (Liza macrolepis), comprising only 17% of the total diet items but contributed 54% of the estimated total dry weight, was the most important diet species. Our results suggest that conservation of the Large-scale Mullet in the habitats is important to this endangered wader.

Seasonal composition and sexual differences in the diet of the White-faced Ibis (Plegadis chihi) were investigated in Buenos Aires Province, Argentina. A total of 88 stomach contents were analyzed, from White-faced Ibis feeding on riparian pastures and grasslands in the Magdalena district, Buenos Aires Province, Argentina. Samples were obtained between 1992 and 1996, covering each season of the year. The trophic spectrum was determined based on the identification of 59 items, mainly belonging to animal taxa. Diet was composed of Insecta (43 items), Arachnida (3 items), Crustacea (5 items), Gastropoda (3 items), Hirudinea (3 items), Amphibia (1 item) and vegetable (1 item). Dietary composition was analyzed in terms of number, frequency of occurrence and volume, for each season and between sexes. Significant differences between sexes were found in the volume of the ingestion consumed.

We conducted an observer-based diet study of Caspian Terns (Sterna caspia) incorporating digiscoping to collect digital photographic vouchers of fish. Observer-based diet studies pose several problems, ranging from differential experience and abilities of observers to the lack of vouchers for confirming identification. One solution to these problems is to recover fish either directly from birds (i.e., trapping, shooting) or ones dropped on the colony. This may not, however, be desirable or achieve adequate sample sizes. Some species are difficult to capture or methods may cause significant disturbance and/or nest abandonment. To overcome these problems, we used a relatively inexpensive new photographic technique known as digiscoping. By holding a high-resolution point-and-shoot digital camera up to the eyepiece of a spotting scope or pair of binoculars, we could take digital photographic vouchers of fish as terns brought them into the colony. During the study, we made 16,423 observations, identifying 92% of the fish to the family (3%), genus (15%), or species (74%) level. We supported these observations with over 2,500 digital photograph vouchers. Vouchers confirmed identification of all fish taxa and allowed for later identification, by us or qualified fisheries biologists, of several species unidentifiable in the field. The ability to have independent experts confirm observations and identify previously unidentifiable observations greatly expanded our understanding of the range of fish taken by Caspian Terns.

Estimating the size of breeding populations of colonial nesting wading birds is a priority for waterbird management but locating colonies can be difficult. Existing methodologies to locate wading bird colonies require use of airplanes and/or a systematic search of likely colony locations on the landscape. This study describes the use of vanishing bearings of Great Blue Herons (Ardea herodias) as they depart coastal foraging sites to determine the number and location of associated breeding colonies. In 2002, frequency analysis of the vanishing bearings identified 23 modes at ten sites while in 2003, 29 modes at 15 sites were identified. Of these modes, about one-half (twelve in 2002 and 15 in 2003) were associated with a known colony. Groupings of vanishing bearings unassociated with known colonies prompted searches for unknown colonies. Searches in 2002 and 2003 found three colonies missed during routine colony inventories using information from the public. Intensive searches in 2004 and 2005 at foraging sites where large colonies had previously abandoned located four previously unknown colonies. These results give confidence that all colonies associated with known foraging sites can be located using this method.

An experimental procedure was set up to test if Carrion Crow (Corvus corone) predation on Little Tern (Sterna albifrons) eggs could be decreased by conditioned taste aversion. The experiment started with a control period, during which 30 artificial Little Tern nests were maintained with quail eggs for 6 days at two study sites. The rate of egg predation was assessed through daily visits and observations of crow behavior. During the treatment period (following 6 days), 15 nests were supplied with eggs pre-treated with methiocarb, an ill-inducing compound, while the other 15 nests were maintained with non-treated eggs. The treatment period was extended by a further period of eight days, during which only treated eggs were deployed at 15 nests. Carrion Crows did not develop any aversive response to the eggs. All treated and untreated eggs were taken by crows from the nests and broken in less than 24 h after delivery. However, treated eggs were apparently not consumed by crows, which suggests that they were able to identify the egg content prior to consumption. The lack of success of our study calls into question the general applicability and effectiveness of this method.

Although the Abdim's Stork (Ciconia abdimii) is a common breeder in the Sahel zone across Africa, its diet during the breeding season has never been studied. Chick meals were sampled in stork nests in West and Central Niger during early July and late August, representing early and mid rainy seasons in the area. The diet consisted of amphibians (Bufo sp.) and a range of insects with grasshoppers (Orthoptera) as the dominant (23 species) group making up 30% and 59% of prey biomass in July and August, respectively. In terms of frequency of occurrence, the important Sahelian pest species Oedaleus senegalensis was the most common grasshopper in the stork chick diet. There was a marked seasonal difference in the relative importance of insects and vertebrates: in July amphibians made up 61% of diet by wet weight, and insects 38%, while in August insects made up 92% of prey wet weight, and amphibians only 6%. The high dependency on amphibians in July was a surprise, but suggests that toads may be the key prey for the adult storks during the incubation period when toads become active while major new insect generations have not yet emerged. The increased importance of insects later in the rainy season reflects the emergence of new generations of grasshoppers, where, in particular, the locally (too) abundant Oedaleus senegalensis becomes the main prey.

The role of spatial, temporal and weather factors on the foraging behavior of migrating Semipalmated Sandpipers (Calidris pusilla L.) was explored during fall staging in the upper Bay of Fundy (Canada) over two years. Factors that influence foraging benefits during migration stopover may influence fitness in a migratory species. The number of captures and success rate peaked during the middle of day regardless of temperature. Pecking rate decreased with increasing temperature while the number of captures and success rate increased suggesting that foraging benefits are lower at low temperatures. The number of captures and success rate did not change as a function of tide stage or time of year despite presumed changes in prey availability and/or density. Running and flying activities were also influenced by time of day and weather factors. Difficulties in locating prey or detecting predators may explain the effect of time of day and increased thermoregulation costs and changes in prey activity are probably involved in explaining how weather factors influence foraging behavior in this species

Grey Herons foraged in a high number only in one of three preferred foraging areas in the Dobczyce Reservoir, S. Poland: (1) the backwater area at the main tributary inlet (MTI), (2) the shore of the near-dam pool (NDP), and (3) shallow lateral bay (SLB). Median value of the fraction of herons foraging in MTI was 64% of all counted in the reservoir in 2001-2002 despite the smallest fish density there (2 times smaller than in NDP, and by one order of magnitude than in SLB). Roach (Rutilus rutilus) was the most abundant both in the heron diet (13 species) and in littoral fish communities (8 species). Total length of prey ranged within 4.2-26.5 cm. The individual size range of littoral fish was similar (4.6-31.5 cm). However, the size distributions in three foraging areas and in heron diet were different. Fish longer than the median total length of heron prey, i.e. ≥8 cm in total length constituted 51.9% of heron diet, 34.7% of the fish community in MTI, 8.5% in the psammolittoral of NDP, and only 5.2% in the phytolittoral of SLB. The strategy of selective choice of longer fish from those occurring at foraging sites allowed greater reward with roughly unchanged foraging cost. This may explain why Grey Heron foraged mainly in the habitat with the lowest fish abundance and highest water turbidity but with the largest prey size.

An adult Herring Gull (Larus argentatus) was observed baiting Goldfish (Carassius auratus) with pieces of bread. Active bait-fishing is mostly known from herons, and a similar behavior was reported in captivity for a Lesser Black-backed Gull (L. fuscus). To our knowledge, we report the first record of bait-fishing, and second record of complex tool-use, for the superorder Charadrii under natural conditions.

Many Palearctic shorebirds spend the northern winter in the islands of the western Indian Ocean. However, only in Madagascar is sufficient wetland habitat available for large numbers but to date these birds have been largely unstudied. Surveys of all wetlands and selected points in the coastal mangrove of southern Melaky and Menabe in western Madagascar in September-November 2004 found 5,485 shorebirds of 14 species. Repeat counts were made at several sites in December 2004 and March-May 2005.