Limnodromus Griseus Research Articles

Migratory strategies across an ecological barrier: is the answer blowing in the wind?

BackgroundEcological barriers can shape the movement strategies of migratory animals that navigate around or across them, creating migratory divides. Wind plays a large role in facilitating aerial migrations and can temporally or spatially change the challenge posed by an ecological barrier, with beneficial winds potentially converting a barrier into a corridor. Here, we explore the role wind plays in shaping initial southbound migration strategy among individuals breeding at two sites along an ecological barrier.MethodsUsing GPS satellite transmitters, we tracked the southbound migrations of Short-billed Dowitchers (Limnodromus griseus caurinus) from two breeding sites in Alaska to nonbreeding sites in coastal Mexico. The breeding sites were positioned in distinct regions along an ecological barrier – the Gulf of Alaska. We investigated potential differences in migratory timing, wind availability, and tailwind support en route across the Gulf of Alaska between individuals breeding at the two sites.ResultsRoute choice and arrival timing to wintering sites differed markedly between the two breeding sites: individuals departing from the more westerly site left at the same time as those from further east but crossed the Gulf of Alaska farther west and arrived along the Pacific coast of Mexico an average of 19 days earlier than their counterparts. Dowitchers from both sites departed with slight tailwinds, but once aloft over the Gulf of Alaska, birds from the more westerly site had up to twelve times more tailwind assistance than birds from the more easterly one.ConclusionsThe distinct migration strategies and degree of wind assistance experienced by birds at these two breeding sites demonstrates how differences in wind availability along migratory routes can form the basis for intraspecific variation in migration strategies with potential carryover effects. Future changes in wind regimes may therefore interact with changes in habitat availability to influence migration patterns and migratory bird conservation.

Touristic activity and disturbances over Nearctic migratory birds oin the coast of Piauí State, Brazil

The migration of birds is a phenomenon that leads thousands of individuals to move between different areas for feeding and breeding, with these movements often crossing geopolitical borders. This behavior is crucial for the survival of many species. However, anthropogenic impacts are affecting the habitats of these species, contributing to the decline in bird populations. In light of this, the aim of this study was to analyze the disturbances caused by tourist activities on migratory birds visiting the estuaries of the Cardoso and Camurupim rivers on the coast of the state of Piauí and propose measures to mitigate disturbances on the birds. Samples were taken at three observation points, where changes in bird behavior in response to tourist activities were analyzed. Binoculars, a photographic camera, and a laser rangefinder were used to assist in delineating impact zones. Although various tourist activities occur in the region, the main disturbances are caused by kitesurfing and tourists walking near the feeding or resting areas of the species. Calidris minutilla, Calidris pusilla, Calidris alba, Actitis macularius, and Charadriius semipalmatus were the least sensitive species to disturbances, reacting more frequently within impact zones Z = 0-30m and Z = 30-60m, while the species Pluvialis squatarola, Numenius hudsonicus, Tringa melanoleuca, Calidris canutus, Limnodromus griseus, and Pandion haliaetus showed greater escape distances. The results of this study show that tourists walking and kitesurfing are the main activities impacting migratory birds in the region, highlighting the need for measures to mitigate such impacts. Based on the results, the creation of minimum protection zones of 160m and 200m is recommended to mitigate disturbances caused by the approach of bathers and kitesurfers.

Effects of Invasive Seaweed Depend on Underlying Physical Habitat Structure

Photo 1. A Green heron, Butorides virescens, forages on a mudflat covered with macroalgae. The dominant alga, Agarophyton vermiculophyllum, is visible as tufts of red-brown thalli and intermixed with Ulva spp., including Ulva lactuca. Photograph credit: Alice Besterman. Photo 2. Agarophyton vermiculophyllum forms mats up to 5 cm in depth above mudflat sediments, and generally between 2 and 3 cm deep. Here, a mat of Agarophyton has accumulated at the edge of a salt marsh, with some stems of Spartina alterniflora visible. The eastern mud snail, Tritia obsoleta (formerly Ilyanassa obsoleta), uses Agarophyton as refuge and substrate for egg-capsule deposition. Photograph credit: Alice Besterman. Photo 3. We used spotting scopes to observe shorebirds foraging across expansive mudflats exposed at low tide in the Virginia Coast Reserve LTER. We identified birds to the lowest taxonomic level, as well as the substrate they were used for foraging (bare mud, macroalgal mats, shallow water, oyster reefs, etc.). In this photograph, oyster (Crassostrea virginica) reef patches are visible in the foreground of the mudflat. Photograph credit: Alice Besterman. Photo 4. Hundreds of shorebirds including Limnodromus griseus (Short-billed dowitcher), Pluvialis squatarola (Black-bellied plover), and Calidris alpina (Dunlin) forage on a bare, topographically smooth mudflat in the Virginia Coast Reserve. Photograph credit: Alice Besterman. These photographs illustrate the article “Mudflat geomorphology determines invasive macroalgal effect on invertebrate prey and shorebird predators” by Alice F. Besterman and Michael L. Pace published in Ecology. https://doi.org/10.1002/ecy.3540.

The Reliability of Measurements of Foraging Behavior in Shorebirds: A Comparison of Real-Time and Slow-Motion Recordings

Data reliability is the degree to which the data can be replicated by the same or different observers and should be one of the most basic aspects of scientific data assessment. Yet, for example, information on the reliability of feeding rate data in shorebirds is strikingly lacking in the literature. In this study, the reliability of foraging behavior metrics collected on Semipalmated Sandpipers (Calidris pusilla) and Short-billed Dowitchers (Limnodromus griseus) during their spring stopovers in Delaware Bay, Maryland, USA, was examined. Using video recordings of 30 foraging individuals scored by four observers, including one experienced observer, assessed: (1) to what extent the data on these two species' foraging rates can be replicated while viewing videos at real-time speed as opposed to videos viewed in slow-motion; and (2) whether intra- and inter-observer reliabilities vary between species and with the observer experience. The results demonstrate that scoring feeding rates in Short-billed Dowitchers does not require the analysis of the footage in slow motion, implying that data may be obtained in real time in the field, following an appropriate training of observers. By contrast, detailed scoring of different foraging techniques in small sandpipers requires either slow-motion reviews of the field-sourced footage, or the clumping of foraging techniques into tactile and visual types to provide sufficient reliability of the data collected in the field if filming of birds is not feasible.

Effects of drought on the abundance and distribution of non-breeding shorebirds in central California, USA

Conservation of migratory species requires anticipating the potential impacts of extreme climatic events, such as extreme drought. During drought, reduced habitat availability for shorebirds creates the potential for changes in their abundance and distribution, in part because many species are highly mobile and rely on networks of interior and coastal habitats. Understanding how shorebirds responded to a recent drought cycle that peaked from 2013 to 2015 in central California, USA, will help optimize management of wetlands and fresh water for wildlife. In the Central Valley, a vast interior region that is characterized by a mosaic of wetlands and agricultural lands, we found 22% and 29% decreases in the annual abundance of shorebirds during periods of 3-year drought (2013-2015) and 2-year extreme drought (2014-2015), respectively, when compared to non-drought years. Lower abundance of shorebirds coincided with significant decreases in the mean proportion flooded of survey units (7% and 9%, respectively) that were reliant on fresh water. Drought was associated with lower abundance within both the interior Central Valley and coastal San Francisco Bay for greater and lesser yellowlegs (Tringa melanoleuca and T. flavipes) and long- and short-billed dowitchers (Limnodromus scolopaceus and L. griseus). Only dunlins (Calidris alpina) had patterns of abundance that suggested substantial shifts in distribution between the Central Valley and coastal regions of San Francisco Bay and Point Reyes. Our results indicate that drought has the potential to reduce, at least temporally, shorebird populations and flooded habitat in the Central Valley, and the ability to respond to drought by taking advantage of nearby coastal habitats may limit the long-term effects of drought on some species. Successful conservation strategies must balance the impacts of reduced habitat availability at interior sites with the ability of some migratory shorebirds to adapt rapidly to shifting distributions of resources.

Identification of priority shorebird conservation areas in the Caribbean.

Despite being geographically central to the Atlantic Americas Flyway for migratory birds, the Caribbean is often overlooked or underappreciated when addressing the conservation of North American shorebirds. To our knowledge, this is the first Caribbean-wide assessment of shorebird use in the region. We analyzed 211,013 shorebird species observations in the insular Caribbean from 2010–2019, representing 78,794 eBird checklists and cumulative total of 2.1 million shorebirds of 45 species. We conclude that priority areas for shorebird conservation include Humedal Sur de Pinar del Río (Humedal Sur de Los Palacios) in Cuba, and Monte Cristi in the Dominican Republic as they each likely support more than 20,000 shorebirds annually, and they host large abundances of geographic populations for particular taxa. Specifically, the former site hosts >10% of Short-billed Dowitchers (Limnodromus griseus griseus/hendersoni), and >1% of Black-bellied Plovers (Pluvialis squatarola cynosurae) and Wilson’s Plovers (Charadrius wilsonia wilsonia), while the latter site supports large numbers of Black-necked Stilts (Himantopus mexicanus). We also identified at least 15 additional sites that likely cross the 1% population threshold for one or more shorebird taxa. These sites may qualify for special international designations such as Important Bird and Biodiversity Areas or as part of the Western Hemisphere Shorebird Reserve Network; 11 of the 17 sites we identified do not hold either of these titles. Data on subspecific or geographic distributions of three species, Snowy Plover (C. nivosus), Black-necked Stilt, and Killdeer (C. vociferous), are insufficient to reveal if the sites with the highest abundances were mostly comprised of Caribbean populations or migrants, but the limited information suggests that they also likely exceed 1% thresholds on several islands. Based on our results, we recommend more extensive systematic surveys of shorebirds in the Caribbean, including research on turnover rates and movements between islands, as well as assimilation of shorebird survey data not yet included in the eBird portal.

The influence of migration patterns on exposure to contaminants in Nearctic shorebirds: a historical study.

Since the 1970s, many populations of shorebirds, including those breeding in the Arctic region, have been declining. One factor that may contribute to some of these declines is exposure to contaminants throughout the annual cycle. Here, we compared contaminant exposure (organochlorines, toxic trace elements) of four Arctic-breeding shorebirds (semipalmated plover Charadrius semipalmatus, semipalmated sandpiper Calidris pusilla, lesser yellowlegs Tringa flavipes, and short-billed dowitcher Limnodromus griseus), collected during breeding, migration, and wintering to examine how and when contaminants might pose a threat to these species. In general, plovers and dowitchers had higher levels of most organochlorine pesticides, and renal cadmium (Cd) and selenium (Se) than the other species. Although we found seasonal differences, no clear patterns in contaminant concentrations among sampling locations were detected but the concentrations found at the breeding grounds were always the highest for chlorinated pesticides and mercury (Hg). Our results suggest that birds migrating south are slowly depurating contaminant burdens, and that spring-migrating birds were exposed to primarily North American rather than Latin American contaminant sources at the time of sampling. We present these data collected in the 1990s to better interpret current-day trends, and potential contaminant exposure impacts on shorebird populations.

Weak niche partitioning by migrating shorebirds in a single-food-type environment

This study examined foraging niche partitioning among coexisting species of shorebirds on a sandy beach dominated by a single food type, Horseshoe Crab ( Limulus polyphemus) eggs, where use of foraging microhabitats of limited variety is temporarily restricted due to tidal cycle. The major goal of the study was to examine whether co-occurring species differed in selection of foraging microhabitats and use of feeding techniques. Ruddy Turnstone ( Arenaria interpres), Red Knot ( Calidris canutus), and Sanderling ( Calidris alba) foraged significantly more on sand and gravel compared to pools and swash zone, Semipalmated Sandpiper ( Calidris pusilla) foraged significantly more on sand and gravel compared to swash zone, but not significantly more compared to pools, while differences in use of microhabitats by Dunlin ( Calidris alpina), and Short-billed Dowitcher ( Limnodromus griseus) were non-significant. Turnstones used digging and turning stones, and pecking significantly more than probing, Semipalmated Sandpipers used pecking significantly more than probing, while all other species used probing significantly more than pecking. Knots and Sanderlings had the highest level of overlap both in use of microhabitats and foraging techniques, while turnstones and dowitchers had the lowest. Ruddy Turnstones were the only birds that used digging and turning stones to obtain food and these two foraging methods seemed to be the most important variables discriminating turnstones from other co-occurring shorebirds. However, despite the slight differences in use of foraging methods and microhabitats by different species, this study documented weak partitioning among shorebirds, particularly between sandpipers and dowitchers. These results indicate that the short-term absence of clear niche partitioning on a local scale may occur in shorebird communities.

Inventory of Lowland-Breeding Birds on the Alaska Peninsula

AbstractWe conducted the first systematic inventory of birds in the lowlands (areas ≤100 m above sea level) of the Alaska Peninsula during summers of 2004–2007 to determine their breeding distributions and habitat associations in this remote region. Using a stratified random survey design, we allocated sample plots by elevation and land cover with a preference for wetland cover types used by shorebirds, a group of particular interest to land managers. We surveyed birds during 10-min counts at 792 points across 52, 5 km × 5 km sample plots distributed from south of the Naknek River (58.70°N,157.00°W) to north of Port Moller (56.00°N,160.52°W). We detected 95 bird species including 19 species of shorebirds and 34 species (36% of total) considered at the time to be of conservation concern for the land managers in the region. The most numerous shorebirds on point counts were dunlin Calidris alpina, short-billed dowitcher Limnodromus griseus, and Wilson's snipe Gallinago delicata. We found the breeding-season endemic marbled godwit Limosa fedoa beringiae at 20 plots within a 3,000-km2 area from north of Ugashik Bay to just north of Port Heiden and east to the headwaters of the Dog Salmon and Ugashik rivers. The most abundant passerines on point counts were American tree sparrow Spizelloides arborea, Lapland longspur Calcarius lapponicus, and savannah sparrow Passerculus sandwichensis. Sandhill crane Antigone canadensis, glaucous-winged gull Larus glaucescens, and greater scaup Aythya marila were also relatively abundant. We categorized habitat associations for 30 common species and found that lowland herbaceous vegetation supported wetland-focused species including sandhill crane, marbled godwit, short-billed dowitcher, and dunlin; whereas, dwarf shrub-ericaceous vegetation supported tundra-associated species such as willow ptarmigan Lagopus lagopus, rock sandpiper Calidris ptilocnemis, and American pipit Anthus rubescens. Tall shrub vegetation was important to several species of warblers and sparrows, as well as one species of shorebird (greater yellowlegs Tringa melanoleuca). We found that point counts augmented with incidental observations provided an almost complete inventory of lowland-breeding species on the study area. These data form a baseline to monitor any future changes in bird distribution and abundance on the Alaska Peninsula.

Shorebird hunting in Barbados: Using stable isotopes to link the harvest at a migratory stopover site with sources of production

ABSTRACT Understanding spatial connectivity of long-distance migrants is important for effective management and conservation of both game and nongame species. Hunting of Nearctic-breeding shorebirds occurs in the Caribbean and northern South America; however, the origins of harvested individuals are generally unknown. We used stable hydrogen isotopes (δ2H) in feathers of juvenile shorebirds to infer the origins of birds harvested at 2 sites in Barbados using probabilistic assignments based on a terrestrial–freshwater δ2H isoscape. We used tissue δ13C and δ15N values to filter individuals that had derived nutrients from marine sources. Natal origins of juvenile American Golden-Plover (Pluvialis dominica), Stilt Sandpiper (Calidris himantopus), Short-billed Dowitcher (Limnodromus griseus), and Lesser Yellowlegs (Tringa flavipes) were predicted to be mainly from the eastern parts of their breeding ranges in eastern Canada, with American Golden-Plover, Stilt Sandpiper, and Short-billed Dowitcher also having h...

Short-billed Dowitcher Limnodromus griseus killed by a Western Gull Larus occidentalis in western Washington, USA

Short-billed Dowitcher Limnodromus griseus killed by a Western Gull Larus occidentalis in western Washington, USA

Niche dynamics of shorebirds in Delaware Bay: Foraging behavior, habitat choice and migration timing

Niche differentiation through resource partitioning is seen as one of the most important mechanisms of diversity maintenance contributing to stable coexistence of different species within communities. In this study, I examined whether four species of migrating shorebirds, dunlins (Calidris alpina), semipalmated sandpipers (Calidris pusilla), least sandpipers (Calidris minutilla) and short-billed dowitchers (Limnodromus griseus), segregate by time of passage, habitat use and foraging behavior at their major stopover in Delaware Bay during spring migration. I tested the prediction that most of the separation between morphologically similar species will be achieved by differential migration timing. Despite the high level of overlap along observed niche dimensions, this study demonstrates a certain level of ecological separation between migrating shorebirds. The results of analyses suggest that differential timing of spring migration might be the most important dimension along which shorebird species segregate while at stopover in Delaware Bay. Besides differences in time of passage, species exhibited differences in habitat use, particularly least sandpipers that foraged in vegetated areas of tidal marshes more frequently than other species, as well as short-billed dowitchers that foraged in deeper water more often than small sandpipers did. Partitioning along foraging techniques was less prominent than segregation along temporal or microhabitat dimensions. Such ranking of niche dimensions emphasizes significance of temporal segregation of migratory species – separation of species by time of passage may reduce the opportunity for interspecific aggressive encounters, which in turn can have positive effects on birds' time and energy budget during stopover period.

Monitoring Migrating Shorebirds at the Tofino Mudflats in British Columbia, Canada: is Disturbance a Concern?

Abstract. The Tofino Wah-nah-jus Hilth-hoo-is Mudflats on Vancouver Island, British Columbia, Canada, include both pristine areas and sites with residential and resort development. Shorebird counts were conducted at six sites around these mudflats in 2011 and compared with historical counts from 1988, 1989, and 1995. Temporal trends of counts did not vary among sites with different levels of disturbance. Over the entire mudflats, counts of Dunlin (Calidris alpina) moving northward had a negative trend over time (βyr = -0.04), as did counts of Western Sandpiper (Calidris mauri; βyr = -0.04), Least Sandpiper (Calidris minutilla; βyr = -0.03) and Short-billed Dowitcher (Limnodromus griseus; βyr = -0.04) moving southward. In contrast, counts of Black-bellied Plover (Pluvialis squatarola; βyr = 0.03) and Semipalmated Plover (Charadrius semipalmatus; βyr = 0.02) moving northward increased over time. Counts of Dunlin and Short-billed Dowitcher were lower at disturbed sites relative to non-disturbed sites, indica...

Nuevos registros de aves para la Isla María Madre, Nayarit, México

The present paper includes nine species of birds here reported from collections made in October 1979 and August 1980. These are: Calidris alpina pacifica, Limnodromus griseus hendersoni, Gallinogo gallinago delicata, Crotophaga sulcirostris sulcirostris, Chloroceryle americano hachisukai, Spiza americana, and Melozpisa lincolnii lincolnii. Fragata magnificens and the exotic Passer domesticus were observed but not collected.

MARITREMA MAGDALENAE N. SP., EIN TREMATODE VON DER ISLA DE SALAMANCA, NORDKOLUMBIEN

A description of Maritrema magdalenae n. sp. from Limnodromus griseus, collected on the Isla de Salamanca (Northern Colombia) is given. Because of morphological differences to all known species, M. magdalenae is considered to be new.

Molecular Analysis of the Value of Horseshoe Crab Eggs to Migrating Shorebirds

Detection of prey DNA from faecal samples is a non-invasive method being successfully applied to the dietary analysis of birds as well as other vertebrates and invertebrates. We have employed this technique to examine the significance of Horseshoe Crab eggs ( Limulus polyphemus) for Dunlins ( Calidris alpina), Semipalmated Sandpipers ( Calidris pusilla), Least Sandpipers ( Calidris minutilla) and Short-billed Dowitchers ( Limnodromus griseus) during northbound migration at their major stopover area in Delaware Bay. This was accomplished through polymerase chain reaction amplification of Limulus DNA from faecal samples using new Horseshoe Crab-specific primers. We detected the consumption of crab eggs in all study species, although results suggest that eggs may be a less important food source for Least Sandpipers than for the other species. Consumption of eggs increases as the migration season progresses, implying a strong preference of birds for this resource at the end of May, when eggs are readily accessible. The results confirm the value of Horseshoe Crab eggs for migrating shorebirds in this crucial stopover area. The Limulus-specific primers we designed can be effectively used for detection of semidigested Limulus DNA from faecal samples and thus they can be employed in the dietary analysis of other predators that seasonally capitalise on Horseshoe Crabs or their eggs.

Roland C. Clement, 1912–2015

Roland Clement was born on November 22, 1912, in Fall River, Massachusetts, the first son of Germain A. Clement of Iseghem, Belgium, a musician, and Angelina Desjardin of Sorel, Quebec, Canada. In 1947 he married Muriel Crowly of Brooklyn, New York, a Yale nurse, who predeceased him in 1998. Roland is survived by three children: Charles (a botanist in Manaus, Brazil); Connie, a public health professional in Toronto and in Nova Scotia, Canada; Alison (Lawrence, a computer programmer in Shelton, Connecticutt, now living in Bar Harbor, Maine), three granddaughters, and two great-grandchildren. Roland died comfortably on March 21, 2015, at his home in Hamden, Connecticut. Family and friends held a celebration of Roland’s life in late March. Roland became interested in birds at age 8 because of a close-up look at a male Black-and-white Warbler. He met no one else interested in birds until age 14, when he joined the Boy Scouts, in which he served as camp naturalist and merit badge examiner for 12 years. Roland won a New England Garden Club scholarship to the Audubon Camp of Maine (1938), where he met Allan D. Cruickshank and Roger Tory Peterson, and returned as second birdman under Cruickshank in 1950. Roland attended parochial schools, skipped high school, did 2 years of business school, and then worked as a bookkeeper/secretary for 12 years. ‘‘Released’’ by the Great Depression in 1933, he started a new career, first banding birds with Maurice Broun at the O.L. Austin Ornithological Research Station, North Eastham, Cape Cod, Massachusetts, then doing 2 years of vocational wildlife management study at the Stockbridge School, University of Massachusetts, Amherst. Roland edited the New England Bulletin of Bird Life for the Boston Museum of Natural History (1942), where he was mentored by Ludlow Griscom. Roland served as U.S. Air Corps weather observer from 1943 to 1945, training in Illinois, Louisiana, and Colorado, before spending a year at Goose Bay, Labrador, and another at Indian House Lake, New Quebec, during which he conducted intensive studies of bird distribution and initiated life history studies. Roland returned to central Labrador for the Carnegie Museum in 1957 and 1958, where he was codiscoverer of the nesting grounds of the Eastern Short-billed Dowitcher. The faunal work from that period was published in W. E. Clyde Todd’s Birds of the Labador Peninsula (1963) and the life histories (Common Redpoll and Eastern White-crowned Sparrow) in A. C. Bent’s series on Life Histories of North American Birds (1968). Roland twice gave papers at AOU Meetings during those years. Roland returned to school on the ‘‘G.I. Bill’’ and obtained degrees from Brown University (B.S. in Botany, 1949) and Cornell University (M.S. in Wildlife Conservation, 1950). Subsequently, he became the first executive secretary of the Audubon Society of Rhode Island (1950– 1958). He then served the National Audubon Society as membership secretary, headquarters biologist, and vice president (1958–1977). He was a principal advocate for the banning of DDT, was personally active in early recovery programs for the California Condor and the Eastern Peregrine Falcon, and was a catalyst in numerous initiatives, including the founding of the Environmental Defense Fund. Roland served as chairman of the U.S. Section of the International Council for Bird Preservation, and later served as Secretary for the Americas, International Committee for Bird Protection (now Birdlife International). Having attended the first international conference of the International Union for Conservation of Nature in Nairobi in 1963, he became so enthralled with African environments that he organized and led small wildlife and birding tours to see the world for a dozen years. In retirement, Roland served as president of the Connecticut Audubon Society and of the Connecticut Ornithological Association and was a visiting fellow at Yale University for several years. In retirement, he became a skilled watercolorist, most often painting birdlife and landscapes, wrote essays shared through a blog, ‘‘Reflections of a Naturalist’’ (http://rolandcclement.blogspot.ca/), and continued traveling. He hosted lecture series in the retirement complexes where he lived, guiding others to reflect upon conservation and environmental challenges, and as recently as 2013 was involved in inventorying birds of a local wetland. Roland’s papers are housed in the Linda Lear Center for Special Collections and Archives at Connecticut College.

Habitat Choice and Niche Characteristics Under Poor Food Conditions. A Study on Migratory Nearctic Shorebirds in the Intertidal Flats of Brazil

The tidal flats of the Bragantinian Peninsula in the tropical part of Brazil harbour wintering and migratory nearctic shorebirds in very high densities, whereas the benthic food supply is very low. In 2001 and 2002 a study was conducted on the habitat choice and distribution of shorebirds to investigate the formation of niches and the spatial distribution under the constraint of a limited food supply. We showed that shorebird densities were not correlated with a range of abiotic variables or with prey density within sites, but that between sites birds tended to select sites with peak prey densities. Two foraging guilds were differentiated: Whimbrel Numenius phaeopus, Willet Tringa semipalmata and Short-billed Dowitcher Limnodromus griseus preferred to forage in the water or on wet sand at the water's edge; while Red Knot Calidris canutus, Grey Plover Pluvialis squatarola, Ruddy Turnstone Arenaria interpres, Semipalmated Sandpiper Calidris pusilla and Semipalmated Plover Charadrius semipalmatus, were found predominantly on dry substrate. Although the birds showed species-specific preferences for characteristics defining microhabitats, niches were broadly overlapping. The results of our study suggest that, in case of a very low food supply, individuals might not be able to react to competition by niche segregation but might be forced to feed in a broad range of available niches.

Biodiversity of birds of 13 de julho avenue mangrove in Aracaju, Sergipe

One agreed to use the denomination 13 de Julho-Atalaia mangrove the mangrove extension of 13 de Julho up to the Districtof Atalaia, Aracaju (SE). In this study area, 6 fixed points were established, of which we did the identification and the counting of thenumber of individuals of each species and the characterization of the type of activity they engage in. From July 2003 to July 2004 atotal of 44 observation journeys were carried out with a minimum duration of 1 hour and a maximal of 4 hours and 20 minutes (meanduration ±2 2 h 36 m). We identified 19 families and 46 birds species, being that 17 of these were migrant coming from the Northhemisphere. Among the observed migrant species four belonged to the Charadriidae family: Charadrius semipalmatus, Charadriuswilsonia, Pluvialis squatarola, Pluvialis dominica; eleven to Scolopacidae: Calidris alba, Calidris pusilla, Calidris fuscicollis, Calidriscanutus, Arenaria interpres Numenius phaeopus, Tringa flavipes, Tringa melanoleuca, Actitis macularia, Catoptrophorus semipalmatus,Limnodromus griseus. Ardeidaes observed in mangroves can be considered residents, in spite of the variations presented by some speciessuch as Egretta thula, Florida caerulea, Casmerodius albus, Butorides striatus, Nyctanassa violaceus and Bubucus ibis.

Helminth Parasites of Dowitchers, Limnodromus griseus from Alaska, and Limnodromus scolopaceus from Montana, U.S.A.

In total, 14 species of helminths (4 trematodes, 8 cestodes, 1 nematode, 1 acanthocephalan) were recovered from 22 long-billed dowitchers, Limnodromus scolopaceus, in eastern Montana. All 22 birds were infected, and species richness ranged from 2 to 6 (mean 3.1). Nine species of helminths (2 trematodes, 7 cestodes) were recovered from 10 short-billed dowitchers, Limnodromus griseus, from Bristol Bay, Alaska. All 10 birds were infected, and species richness ranged from 1 to 5 (mean 3.2). The helminth faunas of both species of dowitchers were dominated by cestodes, including Shipleya inermis and 5 species of Aploparaksis, common to both species of host. Aploparaksis parabirulai is reported for the first time from North America and from L. scolopaceus.