Charadrius Semipalmatus Research Articles

Factors Affecting Parental Behavior in Semipalmated Plovers

We studied Semipalmated Plovers (Charadrius semipalmatus) during two field seasons in Churchill, Manitoba, to examine the contribution of males and females to parental care during incubation and chick rearing, and to test the hypothesis that birds nesting in habitats with higher visibility and more food (i.e. coastal habitats) tend chicks less closely than birds nesting in habitats with lower visibility and less food (i.e. inland habitats). Males at the coast flew and vocalized more than females during the chick-rearing period, and, in both areas, incubated during the darkest hours (2400 to 0220), whereas females incubated from 0220 to 0530. Incubation shifts were longer at night than during the day but did not differ between sexes or habitats. Incubation by males during the darkest hours may allow females to feed when invertebrates are most active, and may be a mechanism by which fe­ males obtain a better energy balance. Coastal habitats contained more food than inland habitats and more potential predators of both chicks and adults. During incubation, parents in coastal habitats exhibited fewer vigilant behaviors than parents in inland habitats, although the overall time budgets for the most common behaviors did not differ between habitats. Parent-chick distances did not differ between coastal and inland habitats, although as chicks became older, they foraged farther from their parents and were brooded less frequently. The apparent response of adults to predators did not differ between the two habitats. The time that parents spent brooding chicks was negatively correlated with ambient temperatures but was not affected by habitat.

Mixed Sexual Dimorphism in Semipalmated Plovers

Sexually dimorphic species generally are characterized by having one sex consistently larger, and often brighter, than the other. Semipalmated Plovers (Charadrius semipalmatus) exhibit a pattern of mixed dimorphism with females that are heavier and having longer wings than males, whereas males have longer toes and bills, and are more colorful than females. Although we found weak evidence that male and female plovers mate assortatively with respect to body size, this likely resulted from birds of certain phenotypes breeding at different times. The mixed pattern of dimorphism in Semipalmated Plovers has probably resulted from different selection pressures, ecological and sexual, operating on different characters.

Effects of Oiling on Feeding Behavior of Sanderlings and Semipalmated Plovers in New Jersey

I examined the foraging behavior of Sanderlings (Calidris alba) and Semipalmated Plovers (Charadrius semipalmatus) during their spring stopover period along the Atlantic coast of southern New Jersey following an oil spill. I used focal animal sampling to test the null hypothesis that there are no differences in foraging behavior as a function of the degree of oiling of birds. Nearly 50% of the foraging time of shorebirds was interrupted during the main period of beach oiling, primarily by clean-up personnel and vehicles that moved up and down the oiled beach, compared to less than 5% of the foraging time disruption at a control beach where birds were interrupted only by walkers and joggers. For both species, the time devoted to feeding decreased significantly, whereas the time devoted to standing about and preening increased significantly as percent of oiled plumage increased. For shorebirds that are already time-stressed in their refueling efforts before their long journey to arctic breeding grounds, these interruptions may prove fatal or might lower reproductive success once they reach the breeding grounds.

Sources of Variation in Clutch Size, Egg Size and Clutch Completion Dates of Semipalmated Plovers in Churchill, Manitoba

Variation in clutch size, egg size and clutch completion dates was studied in a population of Semipalmated Plovers (Charadrius semipalmatus) over 5 summers in Churchill, Manitoba. Clutch size variation was greatest in 1992, a year of unusually low summer temperatures, with almost 25% of clutches containing less than four eggs. More eggs were left unhatched in the nest in 1992 than in any other year. Clutch completion dates were negatively correlated with the average temperature during the pre-laying period. Synchrony of nesting was greatest in 1994, the warmest year. Egg volume and mass were not reduced as a result of the cold summer, and the variation in egg volume and mass attributable to differences among females was similar and significant in all years. Repeatabilities of all egg measurements were high. Egg volume was moderately correlated with female body mass but not with female wing length nor female condition (mass/wing length), a result consistent with that found in other shorebirds. Egg size did not vary consistently with laying order, suggesting strong selection for uniformity in egg size within a clutch.

Population identification of western hemisphere shorebirds throughout the annual cycle

Identification of relationships among geographically distinct populations of migratory species can provide an understanding of breeding and natal philopatry, migration pathways, and population mixing during winter. We used random amplified polymorphic DNA (RAPD) analyses to search for markers specific to difficult‐to‐differentiate shorebird species (e.g. long‐billed dowitcher Limnodromus scolopaceus and short‐billed dowitcher L. griseus) as well as geographically distinct breeding populations of Hudsonian godwits Limosa haemastica, red‐necked phalaropes Phalaropus lobatus, semipalmated plovers Charadrius semipalmatus, dunlin Calidris alpina, pectoral sandpipers C. melanotos, semipalmated sandpipers C. pusilla and western sandpipers C. mauri. Markers clearly differentiated all shorebird species. Estimates of population differentiation varied greatly among species (FST= 0.095–0.685) and correlated with interspecific variation in philopatry and geographical separation of breeding populations. We assigned individuals to putative breeding locales with greater certainty in well‐differentiated species than in poorly differentiated species. Our findings indicate specific phylogeographical structure varies among species, which has strong implications for conservation of habitats within migratory corridors. We suggest that RAPDs are useful in identifying geographical populations of migratory species and that molecular markers should be considered for tracking migratory birds throughout the annual cycle.

Seasonal Variation in Diurnal and Nocturnal Distributions of Nonbreeding Shorebirds at North Humboldt Bay, California

Recent studies of nocturnal foraging by shorebirds (Charadriiformes: Charadrii) suggest that many species feed at night. Much of this research has been qualitative and/or restricted to a small portion of the annual cycle (e.g., a few nights or one season) making it difficult to evaluate the extent to which nocturnal foraging varies seasonally. Consequently, we examined seasonal variation in abundance and distribution of diurnal and nocturnal foraging shorebirds from 10 Jan 1992-10 Jan 1993 at North Humboldt Bay, California. Shorebirds foraged primarily during the day. Overall, day/night frequency of occurrence (percent of censuses with birds) was 87%/48%. In fall, frequency of occurrence of shorebirds differed less between day and night (day/night: 82%/64%) than during spring (day/night: 79%/14%) or winter (day/night: 100%/42%). Moreover, nocturnal abundance of Marbled Godwit (Limosa fedoa), Willet (Catoptrophorus semipalmatus), dowitchers (Limnodromus scolopaceus and L. griseus), and Black-bellied Plover (Pluvialis squatarola) peaked in fall, whereas diurnal abundance of these species peaked in winter (Marbled Godwit, Black-bellied Plover, and dowitchers) or spring (Willet). Taxa varied in day/night patterns. For Scolopacids, diurnal abundance significantly exceeded nocturnal abundance. However, abundance of American Avocet (Recurvirostra americana), Black-bellied Plover, and Semipalmated Plover (Charadrius semipalmatus) did not differ significantly between day and night. Our results suggest that a researcher's choice of season or taxa may influence observed patterns of diurnal and nocturnal distributions of shorebirds considerably.

Use of Landsat TM Imagery in Determining Important Shorebird Habitat in the Outer Mackenzie Delta, Northwest Territories

Landsat Thematic Mapper (TM) imagery was examined to determine important habitats for shorebirds in the outer Mackenzie Delta, Northwest Territories. In June and July 1991 and 1992, 89 ground plots (200 X 200 m) in different habitats were censused for breeding shorebirds. Habitat type in ground plots was determined by observation and compared to the type identified at the site by an unsupervised Landsat classification technique. The most common species of shorebirds breeding in the area were red-necked phalaropes (Phalaropus lobatus) and common snipe (Gallinago gallinago), followed by semipalmated sandpipers (Calidris pusilla), stilt sandpipers (C. himantopus), pectoral sandpipers (C. melanotos), whimbrel (Numenius phaeopus), Hudsonian godwits (Limosa haemastica), lesser golden plovers (Pluvialis dominica), and semipalmated plovers (Charadrius semipalmatus). Long-billed dowitchers (Limnodromus scolopaceus) were rarely seen. Most species were concentrated in areas of low-centre polygons, sedge, and "low terrain" upland tundra (damp and tussocky). However, snipe were most common in dense willow habitat, and semipalmated plovers were found breeding only on sparsely vegetated gravel. Average density of breeding shorebirds in low-centre polygon or "pure" sedge habitat was 82 pairs per sq km in 1991 (SD=73.8), and 49 in 1992 (SD=49.5). Although the Landsat TM imagery analysis used here correctly identified habitat types near the original, intensively surveyed ("ground-truthed") area, it often misidentified habitats at some sites 10 to 30 km away, probably because of irregular flooding and subtle year-to-year differences in water levels in the active outer delta, and edge habitats too narrow to be distinguished by the satellite imagery. However, the technique can identify potential shorebird habitat roughly, and at least eliminate obviously unsuitable areas in large regions of the Arctic.

Biguglia (Corse), quartier d'hiver d'importance internationale pour l'hivernage des canards plongeurs et des foulques macroules - fonctionnement et perspectives (Biguglia Corsica - an internationally important area for wintering coot and diving duck, functioning and outlook): G. Rocamora, Alauda, 60(4), 1992, pp 239–250

Frequent morning surveys of birds were conducted on 1 km of beach in southern California to investigate shorebird use of an exposed sandy beach. The overall mean abundance (98.6 individuals km−1), estimated biomass (9.6 kg km−1), and species richness (5.5 species km−1) of shorebirds observed were very high for a sandy beach in the temperate zone. Eight species, sanderling (Calidris alba), semipalmated plover (Charadrius semipalmatus), marbled godwit (Limosa fedoa), black-bellied plover (Pluvialis squatarola), western sandpiper (Calidris mauri), willet (Catoptrophorus semipalmatus), surfbird (Aphriza virgata), and whimbrel (Numenius phaeopus), occurred in overall mean abundances >1 bird km−1 and accounted for 97% of the abundance and biomass of shorebirds. Sanderlings were the most abundant shorebird every year (64% of individuals and 35% of the biomass). Different species of abundant shorebirds exhibited distinct patterns of use of beach habitat, including fall, spring, and winter peaks in abundance. Temporal variation in shorebird use on seasonal and interannual scales was associated with migration patterns, and also with habitat availability and condition. Seasonal variation in monthly mean abundance and estimated biomass of shorebirds varied over more than an order of magnitude and followed a similar pattern in each year, reaching maxima in the fall or winter (161–280 individuals km−1 and 15.4–23.9 kg km−1) and minima in May or June (3–11 individuals km−1 and 0.8–2.2 kg km−1). A minor peak in shorebird abundance and biomass coinciding with spring migration was observed in April of most years. The number of species of shorebirds observed in individual surveys ranged from 0 to 11 species km−1 and was positively and significantly correlated with abundance. Monthly mean species richness and the total species observed monthly followed similar seasonal patterns, ranging from annual maxima of 7.4–9.1 and 12–17 species km−1 between August and October to minima of 0.8–2.1 and 2–8 species km−1, respectively, during June. In contrast, species turnover was lowest (1.1–1.7) in October and November, and generally highest (2–4) during early summer (June). The amount of sandy intertidal habitat available to shorebirds on the transect was estimated using sand elevations and predicted tide heights. In the fall and winter, the abundance of shorebirds was significantly and positively correlated with tide height, possibly reflecting feeding opportunities and high tide refuge effects during the highest tides. In the spring when sand levels were low, the abundance of shorebirds was negatively correlated with tide height. Prey availability, beach condition and the local availability, and condition of alternative foraging habitats may influence those relationships. Interannual variations in shorebird use and beach condition were observed in the course of the study. During an El Nino Southern Oscillation (ENSO) event (1997–1998), the extent of sandy habitat was greatly reduced and intertidal habitat was mostly converted to rocky substrate. The overall abundance of shorebirds and the mean abundance of some common species (e.g. sanderling) were depressed, and an uncommon species (surfbird, A. virgata) was unusually abundant during the ENSO event. In summary, the results suggest that sandy beaches are important habitat for many species of shorebirds, particularly in areas where alternative coastal foraging habitats, such as coastal wetlands, have become scarce. Understanding the dynamics of and threats to exposed sandy beaches may be increasingly important for shorebird conservation in many coastal regions.

Lipids and lipophilic pollutants in three species of migratory shorebirds and their food in shepody bay (Bay of Fundy, New Brunswick)

AbstractTo study food web transfers of lipids in the intertidal zone, three specimens of each of the semipalmated sandpiper (Calidris pusilla [L.]), the semipalmated plover (Charadrius semipalmatus Bonaparte) and the short‐billed dowitcher (Limnodromus griseus [Gmelin]) were examined after capture during the summer of 1989. They were feeding intensively, prior to migration, on the amphipod,Corophium volutator, on the mudflats of Dorchester Cape, New Brunswick, Canada. The ragworm,Nereis diversicolor, and samples of sea foam were also collected from the mudflats at the same location in 1989 and 1990. Total body lipids of semipalmated sandpipers and short‐billed dowitchers were about 20% of the wet weights, while those of the semipalmated plovers ranged from 35 to 40%. Adipose tissue fatty acids showed a trend from marine fatty acids (20∶5n−3, 22∶6n−3) at 10% ofC. pusilla acids through 5% inC. semipalmatus to 1% inL. griseus. These proportions confirm differences in feeding habits proposed from analyses of gut contents. Short‐billed dowitcher adipose fat included the lowest values of polychlorinated biphenyls (0.078 to 0.266 ppm). The other two species of shore‐birds showed levels as high as 1.64 ppm. Concentrations of 1,1‐bis(4‐chlorophenyl)‐2,2,2‐trichloroethane and 2,2‐bis(4‐chlorophenyl)‐1,1‐dichloroethylene were also variable, but with three exceptions were ≤0.1 ppm of adipose fat. Sea foam collected in the tidal channels and at the edge of the water during the rising tides was found to include diverse lipophilic materials, capable of transfer to higher trophic levels. Triacylglycerols, phospholipids, sterols, hydrocarbons and pigments were typically present at a concentration of 65×103 μg/L. The long‐chain isoprenoid squalene, of endogenous origin and apparently derived from featherwax, was the only hydrocarbon present in the depot fats of the three species of birds analyzed. This indicates that the birds basically inhabited a pristine environment free of hydrocarbon pollutants. The hydrocarbon present in the sea foam consisted of a series of normal alkanes, from C20 to C39, with no odd/even chain‐length preference (carbon preference index=1.008). These hydrocarbons probably originated in detritus from decaying vascular plants but could possibly reflect a very low level of petroleum contamination. The lack of local pollution appears to favor continued success of the migratory pattern of these birds.

The impact of human disturbance on shorebirds at a migration staging area

Human disturbance was investigated as a factor that might limit the capacity of a staging area to support migrating shorebirds. Long-term census data were used to test the hypothesis that human disturbance at an important coastal migration staging area has a negative impact on shorebird movement patterns because of (1) displacement of shorebirds from preferred resting areas within the study area; and (2) abandonment of the study area. Results revealed that four of seven species showed one or more types of movement in response to disturbance. The impact of disturbance was greater on species using the heavily distributed front side of the beach. The abundance of impacted species may be reduced by 50% at high disturbance levels. Abundance of front-beach species, such as red knot Calidris canutus and short-billed dowitcher Limnodromus griseus, declined between 1972 and 1989 more than back-beach species, such as black-bellied plover Pluvialis squatarola and semipalmated plover Charadrius semipalmatus; red knot and short-billed dowitcher declined more at Plymouth Beach than at two comparable, but less disturbed, coastal staging areas and more than the overall eastern North American population. Disturbance is implicated as a potential factor in long-term declines in shorebird abundance at Plymouth Beach. The impacts of disturbance could be reduced or perhaps eliminated by closing one or more small portions of the front beach as refuge resting areas during migration.

Host and geographic distribution of Skrjabinoclava spp. (Nematoda: Acuarioidea) in Nearctic shorebirds (Aves: Charadriiformes), and evidence for transmission in marine habitats in staging and wintering areas

Twelve species of shorebirds belonging to the families Charadriidae (N = 3) and Scolopacidae (N = 9) were infected with 11 species of Skrjabinoclava and there was little overlap of parasites between these two families of birds. Most Skrjabinoclava spp. are transmitted apparently in marine staging and (or) wintering areas of their hosts, as indicated by the presence of larval stages of six species. There was no evidence that transmission occurs on the breeding grounds in freshwater habitats. Skrjabinoclava tupacincai, found predominantly in sanderlings (Calidris alba (Pallas)), is transmitted on the Pacific (Washington, California, Chile) and Atlantic coasts (New Jersey) in winter and the Gulf of Mexico (Florida and Texas) in winter and spring. Skrjabinoclava myersi was found, with a single exception, only in sanderlings, and transmission is apparently restricted to coastal Washington and California in winter. Skrjabinoclava bakeri, found predominantly in western sandpipers (Calidris mauri Cabanis), is transmitted on the Pacific coast (California) and in the Gulf of Mexico in winter. Skrjabinoclava morrisoni and Skrjabinoclava pusillae were found mainly in semipalmated sandpipers (Calidrispusilla (L.)). Both parasites are transmitted in the Gulf of Mexico in spring, but S. morrisoni is also transmitted in the Bay of Fundy in fall. Skrjabinoclava inornatae, found mainly in willets (Catoptrophorus semipalmatus (Gmelin)), is transmitted in Louisiana, Texas, and Peru in winter. Skrjabinoclava kritscheri was found only in marbled godwits (Limosafedoa (L.)), and it is suggested that infected birds collected in southern Alberta in spring acquired their infections while wintering along the Pacific coast of the United States. Skrjabinoclava hartwichi, found in black turnstones (Arenaria melanocephala (Vigors)) wintering in California and ruddy turnstones (Arenaria interpres (L.)) wintering in Peru, is transmitted along the Pacific coast of North America. Skrjabinoclava semipalmatae was found in semipalmated plovers (Charadrius semipalmatus Bonaparte) wintering in California. Skrjabinoclava wilsoniae was found in Wilson's plover (Charadrius wilsonia Ord) wintering in Texas and in a black-bellied plover (Pluvialis squatarola (L.)) migrating through southern Alberta in spring. Skrjabinoclava bartlettae was found in black-bellied plovers collected in southern Alberta in spring and Louisiana in winter.

Sélection des proies par quatre espèces d'oiseaux limicoles (Charadrii) de passage dans l'estuaire du Saint-Laurent lors de la migration vers le sud

The diet of four shorebird species, the Black-bellied Plover (Pluvialis squatarola), Semipalmated Plover (Charadrius semipalmatus), Lesser Yellowlegs (Tringa flavipes), and Semipalmated Sandpiper (Calidris pusilla), was studied on an intertidal mudflat during their southward migration. Mollusks dominate the invertebrate fauna in the feeding area, representing 95% of the organisms in terms of number and biomass. The predatory shorebirds appeared to forage selectively on polychaetes and crustaceans, which represent only 5% of the benthic invertebrates in the feeding area. Lesser Yellowlegs eat nearly exclusively crustaceans. The other three predators feed mainly on Nereis virens and all three select groups of worms that differ significantly by their size, the larger predators consuming the biggest prey. Despite the simultaneous presence of the four predators on the feeding area, they seem to share the resources without overt interspecific competition.

Comparative day and night feeding strategies of shorebird species in a tropical environment

A study was carried out in northeastern Venezuela to determine whether or not shorebirds feed at night in tropical environments. Results show that some Neotropical residents and Nearctic winter migrants feed during darkness. During daylight, Black‐winged Stilts Himantopus himantopus, mexicanus group, were predominantly visual foragers (75% attempts were pecking), performing a tactile type of feeding technique (immersion of the whole head and portion of the neck while searching for food through soft mud) on other occasions. During night‐time, they were almost equally visual (pecking) and tactile (multiple scythelike sweeps) foragers. Greater and Lesser Yellowlegs Tringa melanoleuca and T. flavipes foraged visually during daylight and tactilely (sidesweeping) at night. Short‐billed Dowitchers Limnodromus griseus were tactile feeders (probers) both by day and by night while Semipalmated Plovers Charadrius semipalmatus during daylight and at night and Wilson's Plovers C. tvilsonia by night were sight feeders (peckers). Prey abundance was higher at night than during daylight. Black‐winged Stilts and yellowlegs seemed to feed at night on food items at least partly different from those they fed upon during daylight.

New and described species of Skrjabinoclava Sobolev, 1943 (Nematoda: Acuarioidea) of the proventriculus of nearctic waders (Aves: Charadriiformes) with a review of the genus and a key to species

Nine new species of Skrjabinoclava Sobolev, 1943 are described from the proventriculus of waders (Charadriiformes) in North and South America, and one species (S. tupacincai Freitas and Ibanez, 1970) is redescribed. The nine new species are as follows: (1) Skrjabinoclava hartwichi n.sp. from Arenaria melanocephala; (2) Skrjabinoclava kritscheri n.sp. from Limosa fedoa; (3) Skrjabinoclava bakeri n.sp. from Calidris mauri (type host), C. alba, C. alpina, C. minutilla, C. pusilla, Catoptrophorus semipalmatus, and Limnodromus sp.; (4) Skrjabinoclava morrisoni n.sp. from Calidris pusilla; (5) Skrjabinoclava inornatae n.sp. from Catoptrophorus semipalmatus inornatus; (6) Skrjabinoclava wilsoniae n.sp. from Charadrius wilsonia wilsonia; (7) Skrjabinoclava scmipalmatae n.sp. from Charadrius semipalmatus; (8) Skrjabinoclava pusillae n.sp. from Calidris pusilla; and (9) Skrjabinoclava mycrsi n.sp. from Calidris alba (type host) and C. alpina. Reliable specific characters were noted in the morphology of spicules which make possible the identification of many species. The species of Skrjabinoclava in European waders need to be investigated and in particular the morphology of S. horrida, the type of the genus, needs to be clarified. Taxonomic notes are provided on 13 other previously described species, i.e., S. horrida (Rudolphi, 1809), S. aculeata (Creplin, 1825), S. decorata (Solonitzin, 1928), S. cincli (Yamaguti, 1935), S. solonitzini Sobolev, 1943, S. longifuniculata Sobolev, 1952, S. halcyoni Ryzhikov and Kokhlova, 1964, S. alii Ali, 1968, S. brevispicula Bondarenko and Daiya, 1971, S. amaurornae Schmidt and Kuntz, 1972, S. rallae Schmidt and Kuntz, 1972, S. venusta (Schmidt and Kuntz, 1972), and S. thapari Freitas, 1953. All species so far recorded in the genus occur in the proventriculus of birds, mainly waders, except S. thapari which has been reported in the stomach of Procyon cancrivorus.

Incubation Period and Foraging Technique in Shorebirds

Previous articleNext article No AccessNotes and CommentsIncubation Period and Foraging Technique in ShorebirdsErica NolErica Nol Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 128, Number 1Jul., 1986 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/284543 Views: 12Total views on this site Citations: 10Citations are reported from Crossref Copyright 1986 The University of ChicagoPDF download Crossref reports the following articles citing this article:Ivonne I. Vega‐Ruiz, José Alfredo Castillo‐Guerrero, Eduardo Palacios, Guillermo Fernández Breeding population size and trends of American Oystercatchers on small islands of Bahía Santa María‐La Reforma, Sinaloa, Mexico, Journal of Field Ornithology 90, no.44 (Dec 2019): 325–334.https://doi.org/10.1111/jofo.12315Colleen R. Murchison, Yuri Zharikov, Erica Nol Human Activity and Habitat Characteristics Influence Shorebird Habitat Use and Behavior at a Vancouver Island Migratory Stopover Site, Environmental Management 58, no.33 (Jun 2016): 386–398.https://doi.org/10.1007/s00267-016-0727-xMelissa Rose, Erica Nol Foraging Behavior of Non-Breeding Semipalmated Plovers, Waterbirds 33, no.11 (Mar 2010): 59–69.https://doi.org/10.1675/063.033.0107Hans Schekkerman, Arjan Boele Foraging in precocial chicks of the black-tailed godwit Limosa limosa : vulnerability to weather and prey size, Journal of Avian Biology 40, no.44 (Jul 2009): 369–379.https://doi.org/10.1111/j.1600-048X.2008.04330.xJoseph R Liebezeit, Paul A Smith, Richard B Lanctot, Hans Schekkerman, Ingrid Tulp, Steve J Kendall, Diane M Tracy, Robert J Rodrigues, Hans Meltofte, Julie A Robinson, Cheri Gratto-Trevor, Brian J Mccaffery, Julie Morse, Steve W Zack Assessing the Development of Shorebird Eggs Using the Flotation Method: Species-Specific and Generalized Regression Models, The Condor 109, no.11 (Feb 2007): 32–47.https://doi.org/10.1093/condor/109.1.32Paul M. Nealen An interspecific comparison using immunofluorescence reveals that synapse density in the avian song system is related to sex but not to male song repertoire size, Brain Research 1032, no.1-21-2 (Jan 2005): 50–62.https://doi.org/10.1016/j.brainres.2004.10.059Andrew N Iwaniuk, John E Nelson Developmental differences are correlated with relative brain size in birds: a comparative analysis, Canadian Journal of Zoology 81, no.1212 (Dec 2003): 1913–1928.https://doi.org/10.1139/z03-190Paul M. Nealen, Robert E. Ricklefs Early diversification of the avian brain:body relationship, Journal of Zoology 253, no.33 (Feb 2006): 391–404.https://doi.org/10.1017/S095283690100036XS. Kleindorfer, H. Hoi Nest Predation Avoidance: an Alternative Explanation for Male Incubation in Acrocephalus melanopogon, Ethology 103, no.88 (Apr 2010): 619–631.https://doi.org/10.1111/j.1439-0310.1997.tb00173.xIngvar Byrkjedal Time constraints and vigilance: Breeding season diet of the Dotterel (Charadrius morinellus), Journal für Ornithologie 130, no.33 (Jul 1989): 293–302.https://doi.org/10.1007/BF01644742

Spring Migration of Shorebirds in Panama

The southward migration of shorebirds (Charadrii) through North America often involves stopover areas, places where local populations of actively foraging birds increase to peak abundance over several weeks, then decline (Urner and Storer 1949, Jehl 1963, Schneider and Harrington 1981). The purpose of our study was to determine whether a similar pattern occurs at a Central American location during northward migration in the spring. We chose the Bay of Panama for study because of its geographic and ecological suitability as a staging area. The bay is geographically suitable because it lies between the major wintering areas in South America and breeding grounds in the Arctic for several shorebird species. The bay is ecologically suitable because of the extensive flats uncovered twice a day by the tides, which have a range of 3 to 5 m along the north side of the bay. Primary productivity is high in the bay during the dry season (January to mid-April), due to a local upwelling of nutrient-rich waters (Schott 1935, Glynn 1972). We counted shorebirds at three locations near the south entrance to the Panama Canal (8*56'N, 79032'W) during the last half of the wintering season (January to late May 1978). The sites were chosen because of their accessibility, and because each had intertidal flats extending out several hundred meters from the high tide line. Punta Mala was a protected mudflat lying between Fort Amador and Panama City, east of the canal entrance. Farfan was a protected beach of cobble, sand, and silt located on the western bank of the canal, south of Thatcher Ferry bridge. Mangrove was a protected mudflat with mangrove trees on the same bank of the canal as Farfan, but north of the bridge. Counts from January to March were made while flats were exposed by the tide, or just as the tide was covering the flats. Counts after mid-March were made just as local flats were submerging, to reduce variation in counts due to stage of the tide. To control for the effects of occasional disturbance, we examined the highest count in successive ten-day periods during the study. To control for movement between sites we graphed the highest site count for any one day. Of the eight common species or species groupings, only Ruddy Turnstones (Arenaria interpres) were more numerous during spring (April and May) than during winter (January-March). Black-bellied Plover (Pluvialis squatarola) and Semipalmated Plover (Charadrius semipalmatus) decreased in numbers from January to May (Fig. 1). Wilson's Plover (Charadrius wilsonia) was most abundant in March; the highest count for Short-billed Dowitchers (Limnodromus griseus) and peep (Calidris spp.) occurred in February (Fig. 1). Numbers of Willet (Catoptrophorus semipalmatus) and Whimbrel (Numenius phaeopus) dropped sharply in early April. These declines coincided with the first days of prolonged rain, suggesting that the advent of the rainy season acts as a cue for migratory departure. Lack (in Moreau 1972) noted the sudden departure of Caspian Plover (Charadrius asiaticus) from tropical Africa with the first rains at the end of the dry season. We found no evidence of a spring build-up in numbers at the three sites in the Bay of Panama. The counts in the 200 BLACK-BELLIED 500 WILLET PLOVER

Effects of Tide Cycles on Habitat Selection and Habitat Partitioning by Migrating Shorebirds

-We studied assemblages of feeding shorebirds in three intertidal habitats on the coast of New Jersey during August to document how species segregate spatially both among and within habitats and to determine the effects of tidal cycles on these patterns. The habitats were a sandy beach facing the ocean proper (outer beach), a sandy beach on the mainland side of a barrier island (inner beach), and a small mudflat adjacent to a Spartina alterniflora salt marsh. We were able to identify several microhabitats on the outer beach and mudflat. Most species fed in more than one habitat, but only two, Charadrius semipalmatus and Calidris canutus, used all three habitats regularly. Within habitats, most species exhibited strong preferences for the wettest areas, but we found differences among species in degrees of preference. The least amount of partitioning occurred on the inner beach, where birds crowded into a small zone near the water's edge and had frequent agonistic encounters suggesting intense competition. Shorebird feeding activity was partly a function of tide time: each habitat had a characteristic temporal pattern of use by shorebirds related to tide time rather than diel time; within habitats, we found species-characteristic feeding activity rhythms that were also a function of tide time. Feeding by most species peaked during the first 2 hours after low tide on the outer beach and mudflat. The results are discussed in terms of feeding strategies and interspecific competition.-Department of Biology, Livingston College, Rutgers University, New Brunswick, New Jersey 08903 (Burger, Chase); National Fish and Wildlife Laboratory, National Museum of Natural History, Washington, D.C. 20560 (Howe); and Institute of Animal Behavior, Rutgers University, Newark, New Jersey 07102 (Hahn). Present address of Chase: Department of Biology, Barnard College, New York, N.Y. 10027. Accepted 11 March 1977. (This paper was subsidized by the Migratory Bird Program, U.S. Fish and Wildlife Service.) ALTHOUGH usually solitary on their breeding grounds, migrating shorebirds (Charadrii) often form large, mixed-species aggregations that feed along coastal beaches, mudflats, and marshes. These concentrations of shorebirds result in high population densities in prime feeding areas (Recher and Recher 1969). As these habitats are effectively two-dimensional, spatial segregation of flock members can only occur in a horizontal plane. Increased density may lead to more intense competition for space, resulting in more frequent aggressive interactions and/or niche partitioning. Moreover the cyclic tidal inundation of mudflats and beaches causes changes both in the available feeding space and in the diversity and availability of prey items. Shorebirds respond to these changes by moving continually from one foraging area to another. Studies of ecology of migrating and wintering shorebirds have dealt primarily with feeding methods and rates (Goss-Custard 1969, Ashmole 1970, Burton 1972, Baker and Baker 1973, Baker 1974), feeding dispersions (Goss-Custard 1970a), prey densities (Bengtson and Svensson 1968, Brooks 1967, Goss-Custard 1970b), feeding ecology (Recher 1966, Thomas and Dartnall 1971, Holmes 1966, Holmes and Pitelka 1968), and aggressive behavior (Hamilton 1959, Recher and Recher 1969). Most of these studies stress behavior and diet as related to prey availability or broader ecological considerations. Collectively, most data suggest that shorebird species overlap broadly in their diets and feeding habitats. Competitive exclusion may be avoided because species move from point to point without fully exploiting the available food reserves (Recher 1966). Some studies have also identified patterns of niche partitioning with respect to foods, feeding methods, 743 The Auk 94: 743-758. October 1977 This content downloaded from 157.55.39.211 on Tue, 09 Aug 2016 05:06:27 UTC All use subject to http://about.jstor.org/terms 744 BURGER ET AL. [Auk, Vol. 94

The Occurrence of Certain Nonpasserine Birds in Southern Nevada

Since 1961 the author has spent considerable time in the field in Clark County, Nevada. The following records derived from this field work extend our knowledge of certain species which are considered uncommon to rare in southern Nevada. I am grateful to Charles G. Hansen, biologist, Desert Game Range, for access to his personal records and to the Desert Game Range Narrative Reports (DGRNR). All specimens are on deposit in the Biology Museum, Nevada Southern University. Porphyrula martinica. Purple Gallinule. Two individuals of this species were observed at Tule Springs Park, 13 miles northwest of downtown Las Vegas, in 1966. Single birds were observed there on 7, 8, and 20 September and a male (B-668, weight 183.2 g, left testis 8 x 2 mm, no fat) was collected on 8 September 1966. This constitutes the first record for Nevada. Charadrius semipalmatus. Semipalmated Plover. Spring records of this species for Henderson Slough, one mile north of Henderson, on 26 April 1967 (5 birds) and Tule Springs on 12 and 15 May 1967 (1 bird) supplement those of Grater (Condor 41:221, 1939) and Hayward et al. (Brigham Young Univ. Sci. Bull., Biol. Series 3:8, 1963). Fall records for Henderson Slough on 16 August (2 birds), 23 August (1 bird), and 2 September 1966 (2 birds), and for 1.5 miles west of Logandale on 13 September 1966 (10 birds) appear to be the first for this season in southern Nevada. Specimens were taken on 16 August (B-626, female, ovary 5 x 3 mm, weight 47.8 g, heavy fat), 23 August (B-655, female, ovary minute, 42.4 g, heavy fat), and 2 September (B-743, female, ovary 7 x 1.5 mm, 39.2 g, moderate fat). Charadrius alexandrinus. Snowy Plover. This species is an uncommon transient in Nevada. I have records of single birds of Henderson Slough on 16 and 23 August 1966. A female (B-627, ovary 5 x 3 mm, 31.2 g, light fat) was collected on 16 August. These appear to be the first fall records for southern Nevada. Arenaria interpres. Ruddy Turnstone. Alcorn (Condor 44:81, 1942) lists the single previous Nevada record of this species. A male (B-665, left testis 3 x 0.5 mm, 74.4 g, light fat) was collected 1.5 miles west of Logandale on 13 September 1966. Erolia bairdi. Baird's Sandpiper. Hayward et al. (op. cit., p. 9) give the only previous report of this species for southern Nevada. There is an unpublished record for Corn Creek on 22 April 1946 (DGRNR, January-April 1946). I have additional records for three birds 1.5 miles west of Logandale on 13 September 1966 (female collected, B-666, ovary 3 x 3 mm, 32.3 g, light fat) and for one at Tule Springs Park on 2 May 1967. Crocethia alba. Sanderling. The Sanderling has not been reported previously for southern Nevada. I saw a single bird at Tule Springs Park, 1-3 May 1966.

Continuous Recording of Bird Nesting Visits using Radioactive Tagging

IN view of the successful application of radioactive tagging in entomology in Central Africa, I have investigated the potentiality of the method as a tagging technique in ornithology. Because the detection range of small amounts of radioactive material is only of the order of feet, the method requires the close proximity of the labelled bird and the radiation detector. It was decided to use the method to obtain data on the bird's nesting visits, and the tests not only demonstrated the potentiality of the method but also provided useful data on behaviour. A search of the literature revealed that Barbour1 made similar studies on the prairie vole (Microtus ochrogaster). Barbour used cobalt-60 as the radioactive tagging material, and the signal from the radiation detector was recorded on a tape recorder. Griffin2 has given a thorough discussion on the maximum permissible dose rate to be used for tagging animals under natural conditions, and mentions, without going into detail, an experiment on the semi-palmated plover Charadrius semipalmatus.

Radioactive Tagging of Animals Under Natural Conditions

EcologyVolume 33, Issue 3 p. 329-335 Article Radioactive Tagging of Animals Under Natural Conditions Donald R. Griffin, Donald R. Griffin Department of Zoology, Cornell University, Ithaca, New YorkSearch for more papers by this author Donald R. Griffin, Donald R. Griffin Department of Zoology, Cornell University, Ithaca, New YorkSearch for more papers by this author First published: 01 July 1952 https://doi.org/10.2307/1932828Citations: 17AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume33, Issue3July 1952Pages 329-335 RelatedInformation