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Sites where Barrow's Goldeneye (Bucephala islandica) undergo remigial molt and fall staging are poorly known, with only two major sites documented in Alaska and the Yukon Territory. Satellite telemetry, aerial surveys and ground surveys were used to identify previously unknown molting and fall staging areas in the Boreal Transition Zone (BTZ) of northern Alberta. Of 816 wetlands surveyed between 2004 and 2006 in the BTZ, 40–45% (105–127 lakes annually) had molting goldeneyes. Of these, 1.3–3.3% were used by large aggregations of goldeneyes (>100 birds). Two wetlands, Cardinal and Leddy Lakes, were particularly important, with an estimated 5,000–7,000 Barrow's Goldeneyes, primarily adult males, using these sites during remigial molt and fall staging. Birds used these sites up to five months or over one-third of their annual cycle. Half of adult males marked with satellite transmitters at a breeding area in interior British Columbia used Cardinal Lake for postbreeding activities. Discovery of these sites represents some of the largest concentrations of molting Barrow's Goldeneyes in North America, and the only major molting sites currently known for the intermountain breeding portion of the western population. Protection of Cardinal and Leddy Lakes, and other significant molting and staging sites within the BTZ, should be a priority conservation effort for this species.
Decline of the Dusky Canada Goose (Branta canadensis occidentalis; hereafter, Dusky Goose) population on the western Copper River Delta (CRD) prompted the establishment of an artificial nest island (island) program in 1983. A retrospective analysis of the program was conducted to examine general trends in island use and nest success from 1984–2005. A series of candidate models was generated to determine how habitat, island and biological variables were associated with island use and nest success from 1996–2005. Use of islands by Dusky Geese increased between 1987 and 2005 from 10% to 44%; apparent nest success averaged 64 ± 4% and showed no trend with year. Island use was consistently and strongly associated with the previous year's island status. The odds of nesting on an island that contained a successful nest the previous year were four times greater than for islands not used the previous year. Likelihood of island use was highest at moderate shrub cover and increased with shrub height. Likelihood of nest success increased on islands further from shore. The influence of year suggests the presence of alternate prey and predator abundance is more important to nest success than island features. The increasing use of islands while the CRD Dusky Goose population has been declining indicates that islands may be increasingly important to population productivity. However, quantifying the contribution of the island program requires a better understanding of other population metrics, such as gosling mortality.
Habitat use, diet and foraging activity of male Red-breasted Mergansers (Mergus serrator) undergoing flightless wing molt along the shores of Anticosti Island, Gulf of St. Lawrence, Canada, were studied in 2005 and 2006. Red-breasted Mergansers used clear, shallow waters (≤12 m depth) that were near shore (<850 m) and over a sand-rock substrate with stands of rockweed (Fucus spp.) and kelp (Laminaria spp.). Foraging flocks used in tertidal and shallow subtidal areas (<4 m depth), whereas nonforaging flocks often used deeper subtidal waters farther offshore. Eighty percent of esophagi from 30 collected Red-breasted Mergansers contained ≥ 1 fish. Grubby (Myoxocephalus aenaeus) and sandlance (Ammodytes spp.) were in 43–53% of esophagi, and their relative abundance in an esophagus averaged 29–36%. Birds spent an average 23% of the diurnal period foraging, but foraged nearly 70% of the time when the tide was low in the morning and evening. The proportion of time that males devoted to foraging during the first half of the flightless season (18%; 19 July–12 August) was nearly half that in the second half of the season (30%; 13 August–5 September). The shallow waters along the shores of Anticosti Island are of particular importance to Red-breasted Merganser populations in eastern North America because 1) >3000 males undergo wing molt at the island and 2) these habitats are generally free of human disturbance during the flightless period.
Total annual seabird bycatch in the U.S. Atlantic pelagic longline fishery was estimated from observer data by means of alternative methods to address the low frequency and uneven distribution of bird bycatch observations. Models used for estimation included generalized additive models (GAM), generalized linear models (GLM) and GLM with spatial or spatio-temporally auto correlated bycatch observations (s-GLM). Models were fitted separately to the probability of non-zero seabird capture (presence/absence) and to the numbers of seabirds per non-zero capture (positive bycatch); final estimates were obtained as the product of the two. Best-fitting models included latitude, longitude and quarter of year as covariates for presence/absence, and numbers of hooks per set for positive bycatch. Among the models compared, GLM gave the most consistent predictions of annual total seabird captures. For 2008, the most recent year modeled, GLM predicted 81 seabirds caught in 8,862 sets. The number is small on an Atlantic-wide or world-wide scale but is concentrated in an area of high species diversity that includes relatively small populations. GLM was recommended to be used in future Atlantic pelagic longline seabird bycatch estimation.
To find morphological characteristics that might identify the sex of Atlantic Puffins (Fratercula arctica), body morphometrics (wing chord, culmen length, bill depth, number of bill grooves, and head-bill length) and presence or absence of a brood patch were compared in a sample of 195 adult Atlantic Puffins of known genetic sex caught on Machias Seal Island, in the Bay of Fundy, Canada. Discriminant Function Analysis (DFA) was performed on 98 birds, and then tested on a separate, independent dataset of 97 birds. The measurements that best predicted sex were culmen length, bill depth, and head-bill length, which correctly classified 81% of our sample. The second-best function included only bill depth and head-bill length, which classified 77% of our sample correctly. Testing the three-predictor discriminant function on a second dataset resulted in a 73% correct classification for the first discriminant equation, and 79% for the second. Classification success was improved to 81% by removing younger birds (with <1.5 grooves), and to ∼90% by further excluding non-breeding birds (those without a broodpatch).
Individualized markers that allow organisms to be identified without recapture are invaluable for studies of survival, movement, and behavior. Nape tags consisting of brass safety pins with unique combinations of two or three colored plastic beads were used to mark 5,868 American Coot (Fulica americana) chicks and 331 Ruddy Duck (Oxyura jamaicensis), 157 King Eider (Somateria spectabilis) and 664 White-winged Scoter (Melanitta fusca deglandi) ducklings. These markers allowed for documentation of parent-offspring interactions, post-hatching survival, brood movements and brood-mixing behaviors. Nape tags were inexpensive, easy to make, easy to observe with binoculars or spotting scopes and provided over 100 two-bead or 1,000 three-bead color combinations for individual identification. For coots, there was no evidence of color biases affecting parental care or offspring survival, although some colors (white, yellow) were easier to detect than others (brown). The only observed problem was marker loss, with tag loss rates reaching 20% near fledging age. Nape tags worked effectively on coots and ducklings and may be useful for other precocial waterbirds.
Little is known about the population status of many marsh-dependent birds in North America but recent efforts have focused on collecting more reliable information and estimates of population trends. As part of that effort, a standardized survey protocol was developed in 1999 that provided guidance for conducting marsh bird surveys throughout North America such that data would be consistent among locations. The original survey protocol has been revised to provide greater clarification on many issues as the number of individuals using the protocol has grown. The Standardized North American Marsh Bird Monitoring Protocol instructs surveyors to conduct an initial 5-minute passive point-count survey followed by a series of 1-minute segments during which marsh bird calls are broadcast into the marsh following a standardized approach. Surveyors are instructed to record each individual bird from the suite of 26 focal species that are present in their local area on separate lines of a datasheet and estimate the distance to each bird. Also, surveyors are required to record whether each individual bird was detected within each 1-minute subsegment of the survey. These data allow analysts to use several different approaches for estimating detection probability. The Standardized North American Marsh Bird Monitoring Protocol provides detailed instructions that explain the field methods used to monitor marsh birds in North America.
Whimbrels (Numenius phaeopus) were monitored during spring migration across a network of ten aerial transects within the barrier island-lagoon system along the lower Delmarva Peninsula, Virginia, USA. Transects were surveyed weekly from the last week of April through the first week of June (1994–1996, 2008–2009). Whimbrel numbers increased to a peak during the first and second weeks of May then decreased sharply during the third and fourth weeks of May in all years. Between the 1990's and 2000's, peak numbers declined by 50%, corresponding to a 4.2% annual rate of decline. A similar decline was detected in accumulated, season-wide numbers. Though similar in pattern, migration phenology was significantly different between the decades. The phenology difference resulted from a greater reduction in numbers during the first half of the study period compared to the last. Habitats used by Whimbrels (N = 31,314) included mudflats (95%) and salt marshes (5%). Habitat-specific densities (birds/km2) were 443 ± 26.6 and 9 ± 1.6 (mean ± SE) for mudflat and marsh patches, respectively, during the 1990's and 222 ± 11.1 and 8 ± 4.6 during the 2000's. These results support suggestions that Whimbrels are declining on the Hudson Bay breeding grounds and perhaps at major Atlantic Coast wintering sites.
Long-jump migrant shorebirds have brief windows during spring stopover to acquire the energy needed to complete migration. Red Knots (Calidris canutus) refueling on Horseshoe Crab (Limulus polyphemus) eggs in Delaware Bay can meet their energy needs foraging only by day. In nearby Virginia, thousands of Red Knots stop over, but primarily low-quality, hard-shelled prey are available. One tactic Red Knots may use to meet their energy demands with such prey might be to extend their foraging time by feeding at night. To estimate the length of the foraging day in Virginia, daylight feeding was studied during three spring stopover periods (2008 to 2010), and night feeding was studied in 2010. Red Knots foraged 76 ± 3 SE% of the time in 2008 and 2009 combined, and 59 ± 3% of the time in 2010, during 3-minute observations. In 2010, Red Knots foraged 51 ± 7% of the time during a continuous 7-h daytime observation and 77 ± 5% of the time during a continuous 8-h night time observation on the same island. Given constraints on energy intake, night foraging by Red Knots in Virginia may be necessary for birds to attain sufficient mass to complete migration.
Studying the diet of top marine predators, such as seabirds, is important in understanding their place in the trophic network and effects of global climate change, but knowledge of the diet of several procellariiformes remains anecdotal. The diet of Bulwer's Petrel (Bulweria bulwerii) in the Azores was studied over two consecutive years using stomach flushings from 85 birds. The frequency of occurrence of prey taxa (%0) was similar in both years (χ2 = 5.396, d.f. = 5, p = 0.370), with squid being the most common. Fish and squid were of similar occurrence by number (%N) in the diet (49% and 51%, respectively) in 1998 but in 1999 fish were more numerous (62% against 38% for squid). Squid lower beaks from five families and fish otoliths from six families were identified, representing 20 taxa. The most abundant prey in both years were squid Pyroteuthis margaritifera and the mesopelagic fish Electrona risso. The maximum standard length offish and squid consumed was 7 cm and 11 cm, respectively. Given most of the identified prey are luminescent, the findings corroborate earlier studies suggesting Bulwer's Petrel feed on small mesopelagic prey that migrate to the surface at night.
The Yellow-breasted Crake (Porzana flaviventer) is a poorly-known Neotropical rail found in densely vegetated freshwater wetlands; a single nest record exists for Puerto Rico. In May 2001, the crake was detected in managed impoundments of the Humacao Nature Reserve, located in southeastern Puerto Rico. Yellow-breasted Crakes were regularly observed during monthly surveys of the impoundments with as many as nine individuals detected during an April 2002 survey. Systematic nest searches during 2001–2002 located fifteen nests in approximately 13 ha of newly created wetlands. The nests were more common in Eleocharis mutata, Cyperus ligularis, and Paspalum vaginatum. Nests had an average clutch size of 3.7 (±0.31) eggs and brood size of 2.7 (±0.5) chicks; hatching success was 65% and nesting success 40%. Six nests were depredated. The nesting activity of Yellow-breasted Crake at the Humacao Nature Reserve suggests wetland management in abandoned sugarcane areas of coastal Puerto Rico may benefit waterbird species of concern. Future research should determine abundance estimates and habitat relationships for this secretive species.
The coast of the state of Paraíba, northeastern Brazil, was surveyed for migratory shorebirds during northern summer and the southward migration period, late May through October 2010. Shorebirds were counted along beaches and rivers mouths. A total of eleven species was recorded. The most common were Semipalmated Plover (Charadrius semipalmatus), Semipalmated Sandpiper (Calidris pusilla), Whimbrel (Numenius phaeopus) and Black-belled Plover (Pluvialis squatarola). The highest richness, diversity, abundance and frequency of birds occurred on the two largest estuaries, Paraíba do Norte and Mamanguape, during southward migration period.
As the importance of the Black Sea for wintering waterbirds is poorly known, the species composition and abundance of waterbirds wintering on the Crimean Peninsula coast (Northern Black Sea) was investigated in two habitat types: urban areas and open sea coast. Of 27 waterbird species, 25 were recorded in urban areas, and the dominants were Coot (Fulica atra), Black-headed Gull (Larus ridibundus) and Common Gull (Larus canus). On the open sea coast, fifteen species were recorded, the dominants being Coot, cormorants (Phalacrocorax carbo and Phalacrocorax aristotelis) and Great Crested Grebe (Podiceps cristatus). The species structure of the wintering waterbird community differed significantly between habitats. A trait of the open sea coast community was the high diversity and domination of diving ichthyophagous species. Waterfowl were recorded only in urban areas, which increased species diversity in this habitat. The number of birds wintering on the open sea coast was significantly lower than in the urban areas. Males dominated among ducks, and adult birds dominated among Black-headed and Common Gulls wintering in urban areas. The age structure of Caspian Gulls (Larus cachinnans) differed significantly between the two habitats, with adults dominant on the open sea coast, and immature birds making up more than half of all recorded Caspian Gulls in urban areas. The importance of the Black Sea for wintering waterbirds has been underestimated. Marine and coastland ecosystems with concentrations of waterbirds should be designated and protected as Important Bird Areas (IBAs).
Bird surveys were carried out from 1973 to 2010 in Mar Chiquita, an extensive saline lake and associated Dulce River marshes in central Argentina. The wetland has had marked fluctuations in water level and salinity over the past four decades. At the beginning of the 1970s, Mar Chiquita experienced a large drop in level and there were no waterbirds on the Segundo River mouth. By 1974 the lake had recovered its level and the Segundo River estuary had formed, harboring large concentrations of local waterbirds and Nearctic shorebirds. From mid-1977, a rise in water level led to the disappearance of the Segundo River estuary and by 2003 the lake area had expanded by about 3.5 times and covered half of the Dulce River marshes. Consequently, the wetland, especially the river estuaries, became less important for local waterbirds and Nearctic shorebirds. Since 2003 Mar Chiquita has fallen 4 m, beaches have formed and salinity has increased, but currently there are no Nearctic shorebird concentrations. For the site to recover its importance for birds, Mar Chiquita should continue dropping and salinity continue increasing.
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