scholarly journals Flyway-Scale Variation in Plasma Triglyceride Levels as an Index of Refueling Rate in Spring-Migrating Western Sandpipers (Calidris Mauri)

The Auk ◽  
2007 ◽  
Vol 124 (3) ◽  
pp. 886-897 ◽  
Author(s):  
Tony D. Williams ◽  
Nils Warnock ◽  
John Y. Takekawa ◽  
Mary Anne Bishop
Keyword(s):  
San Francisco ◽  
Migratory Birds ◽  
San Francisco Bay ◽  
Linear Trend ◽  
Plasma Triglyceride ◽  
Significant Linear Trend ◽  
Calidris Mauri ◽  
Stopover Sites ◽  
Breeding Grounds ◽  
Western Sandpipers

Abstract We combined radiotelemetry, plasma metabolite analyses, and macro-invertebrate prey sampling to investigate variation in putative fattening rates (estimated as plasma triglyceride levels) at the flyway scale in Western Sandpipers (Calidris mauri) migrating between Punta Banda, Mexico (31°N), and Hartney Bay, Alaska (60°N), a distance of 4,240 km. Birds were caught at a wintering site (San Francisco Bay) and eight stopover sites along this Pacific Flyway. Body mass was higher in females than in males at six sites, but variation was not correlated with latitude for either sex, and the relationship of change in mass by date within sites was uninformative with regard to possible latitudinal variation in fattening rates. At San Francisco Bay, triglyceride levels were higher in the spring than in the winter. Mean plasma triglyceride varied among stopover sites, and there was a significant linear trend of increasing triglyceride levels with latitude as birds migrated north. At San Francisco Bay, length of stay was negatively related to triglyceride levels. However, plasma triglyceride levels at wintering or initial stopover sites (San Francisco and Punta Banda) did not predict individual variation in subsequent rates of travel during migration. We found no significant relationship between triglyceride levels and prey biomass at different stopover sites, which suggests that the latitudinal pattern is not explained by latitudinal changes in food availability. Rather, we suggest that differences in physiology of migratory birds at southern versus northern stopover sites or behavioral differences may allow birds to sustain higher fattening rates closer to the breeding grounds. Variación a la Escala de Corredores de Vuelo en los Niveles de Triglicéridos Plasmáticos como un Índice de la Tasa de Reabastecimiento durante la Migración de Primavera en Calidris mauri

scholarly journals Seasonal, Age, and Sex Differences in Weight, Fat Reserves, and Plasma Corticosterone in Western Sandpipers

The Condor ◽  
2003 ◽  
Vol 105 (1) ◽  
pp. 13-26 ◽  
Author(s):  
Kathleen M. O'Reilly ◽  
John C. Wingfield
Keyword(s):  
Annual Cycle ◽  
San Diego ◽  
Spring Migration ◽  
Autumn Migration ◽  
Calidris Mauri ◽  
Fat Reserves ◽  
Stopover Sites ◽  
Breeding Grounds ◽  
Western Sandpipers ◽  
Bodega Bay

Abstract Western Sandpipers (Calidris mauri) were followed throughout their annual cycle along the Pacific Coast of North America. Changes in body condition and corticosterone were tracked at two overwintering sites (Ensenada, Mexico, and San Diego, California), four migration stopover sites (Bodega Bay, California, Grays Harbor and False Bay, Washington, and Hartney Bay, Alaska), and a breeding site (Nome, Alaska). Adult males and females had elevated weight and fat scores during spring migration, breeding, and autumn migration relative to lean levels during winter. Although elevated mass and fat reserves may hinder escape from predators and are not necessary at wintering sites with benign conditions, the cost-benefit trade-offs with weight and agility shift during migration and breeding. Extra fat and muscle are necessary for fueling the long flight to and from the breeding grounds and serve as a hedge against unpredictable food and weather conditions on the breeding grounds. First-year birds weighed less and had lower fat reserves at smaller stopover sites than migrants at a large stopover site. Plasma levels of corticosterone revealed seasonal differences in the adrenocortical response to stress, although initial levels were fairly consistent across seasons. The highest stress response of the annual cycle in males was during autumn migration, in contrast to the lowest levels during early spring migration, breeding, and overwintering. Late-spring migrants and autumn premigrants had intermediate stress responses. An emerging pattern from this and other shorebird studies is that migrants with imminent flights of more than 1000 km have elevated corticosterone levels. Diferencias Estacionales de Edad y Sexo en Peso, Reservas de Grasa y Corticosterona Plasmática en Calidris mauri Resumen. Se siguieron individuos de Calidris mauri a través de su ciclo anual a lo largo de la costa Pacífica de Norteamérica. Se evaluaron los cambios en la condición corporal y la corticosterona en dos sitios de invernación (Ensenada, México y San Diego, California), cuatro sitios de escala migratoria (Bodega Bay, California, Grays Harbor y False Bay, Washington, y Hartney Bay, Alaska) y un sitio reproductivo (Nome, Alaska). Los machos y hembras adultos tuvieron pesos y niveles de grasa altos durante las épocas de migración de primavera, reproducción y migración de otoño con relación a los niveles magros del invierno. Aunque presentar masa elevada y reservas de grasa puede limitar el escape de los depredadores y no es necesario en los sitios de invernada con condiciones benignas, existe un cambio en la solución de compromiso entre el costo-beneficio del peso y la agilidad de vuelo durante la migración y la reproducción. La grasa y músculos adicionales son necesarios para proveer combustible para los largos vuelos hacia y desde las áreas de reproducción y sirven como protección contra condiciones alimenticias y climáticas impredecibles en las áreas reproductivas. Las aves añales pesaron menos y tuvieron menos reservas grasas en sitios de escala pequeños que los migrantes en un sitio de escala grande. Los niveles plasmáticos de corticosterona mostraron diferencias estacionales en la respuesta adrenocórtica al estrés, aunque los niveles iniciales fueron relativamente consistentes a través de las estaciones. La respuesta al estrés más alta del ciclo anual de los machos se presentó durante la migración de otoño, contrastando con los niveles más bajos durante el inicio de la migración de primavera, la época reproductiva y la época de invernación. Las aves que migraron temprano en la primavera y las premigrantes de otoño presentaron niveles intermedios de respuesta al estrés. Un patrón que emerge de éste y otros estudios sobre aves marinas es que las migratorias que hacen vuelos de más de 1000 km presentan niveles elevados de corticosterona.

Evidence for sexual partitioning of foraging mode in Western Sandpipers (Calidris mauri) during migration

2004 ◽  
Vol 82 (7) ◽  
pp. 1035-1042 ◽  
Author(s):  
Kimberley J Mathot ◽  
Robert W Elner
Keyword(s):  
Population Level ◽  
Distribution Patterns ◽  
Differential Distribution ◽  
Foraging Mode ◽  
Stopover Site ◽  
Calidris Mauri ◽  
Stopover Sites ◽  
Prey Resources ◽  
Western Sandpipers ◽  
Induced Changes

Migrating Western Sandpipers, Calidris mauri (Cabanis, 1857), observed feeding at an intertidal stopover site on the Fraser River delta, British Columbia, shifted their foraging mode from surface-pecking to probing over a 3-week period in April and May. We tested possible mechanisms to account for the field observations. Using control and shorebird exclusion plots over a 3-month period bracketing the migration, we determined that neither seasonal nor shorebird-induced changes in the relative availability of epifaunal compared with infaunal prey accounted for the decline in the prevalence of epifaunal feeding behaviour. However, strong peaks in both epi- and in-faunal prey densities coincided with the migration period, suggesting that migratory timing may be linked with the productivity schedule of major stopover sites. Males, which precede females in the migration and have relatively shorter bills, were observed to engage in epifaunal feeding more frequently than females. Thus, while foraging behaviour of the Western Sandpiper at a population level appears "plastic", the feeding repertoire of individuals is more specialized and results in sexual partitioning of prey resources. The implications of our findings for differential distribution patterns over the nonbreeding range and sex-related differences in contaminant profiles are discussed.

Trace element profiles as unique identifiers of western sandpiper (Calidris mauri) populations

2007 ◽  
Vol 85 (4) ◽  
pp. 579-583 ◽  
Author(s):  
D.R. Norris ◽  
D.B. Lank ◽  
J. Pither ◽  
D. Chipley ◽  
R.C. Ydenberg ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
San Francisco ◽  
Migratory Birds ◽  
Calidris Mauri ◽  
Linear Discriminant ◽  
Wintering Areas ◽  
Trace Element Profiles ◽  
High Degree ◽  
Global Population

Understanding the ecology and evolution of migratory animals requires information on how populations are geographically linked between periods of the annual cycle. To examine whether trace elements could be used to track migratory birds, we analyzed concentrations of 42 trace elements in feathers of western sandpipers ( Calidris mauri (Cabanis, 1857)) that were grown at five different wintering sites ranging from San Francisco Bay (USA) to the Bay of Panama. Linear discriminant analysis of 15 elements correctly classified all 26 individuals to their wintering sites, including two sites that were separated by less than 3 km. A randomization procedure confirmed the robustness of these findings. Our analysis suggests that trace elements can be used to assign individuals to specific sites of origin. Although we did not sample feathers from all wintering areas, the regions our sites represented comprised a significant percentage of the global population. However, since trace element profiles appear to be highly specific to geographic sites, we suggest that this technique is best suited for cases where samples can be obtained from the majority of populations throughout a species range. Thus, under certain circumstances, trace element profiles may provide the potential to identify populations with a high degree of spatial accuracy.

scholarly journals Avian Use of Agricultural Areas as Migration Stopover Sites: A Review of Crop Management Practices and Ecological Correlates

2021 ◽  
Vol 9 ◽  
Author(s):  
J. David Blount ◽  
Joshua J. Horns ◽  
Kyle D. Kittelberger ◽  
Montague H. C. Neate-Clegg ◽  
Çağan Hakkı Şekercioğlu
Keyword(s):  
Migratory Birds ◽  
Bird Species ◽  
Migratory Bird ◽  
Farming Practices ◽  
Stopover Sites ◽  
Ecological Correlates ◽  
Breeding Grounds ◽  
Stopover Habitat ◽  
Crop Types ◽  
Agricultural Areas

An estimated 17% of migratory bird species are threatened or near threatened with extinction. This represents an enormous potential loss of biodiversity and cost to human societies due to the economic benefits that birds provide through ecosystem services and ecotourism. Conservation of migratory bird species presents many unique challenges, as these birds rely on multiple geographically distinct habitats, including breeding grounds, non-breeding grounds, and stopover sites during migration. In particular, stopover habitats are seldom studied relative to breeding and non-breeding habitats, despite their importance as refueling stations for migratory birds. In this study, we summarize the current research on the use of temporary primary crops by birds during migration and we assess the species characteristics and agricultural practices most often associated with the use of cropland as stopover habitat. First, we conducted a systematic review of the literature to document the effects various farming practices and crop types have on the abundance and diversity of migratory birds using agricultural areas for stopovers. Second, we analyzed the ecological correlates of bird species in the Northern Hemisphere that predict which species may use these areas while migrating. We ran a GLMM to test whether primary diet, diet breadth, primary habitat, habitat breadth, or realm predicted stopover use of agricultural areas. Our review suggests that particular crop types (principally rice, corn, and sunflower), as well as farming practices that result in higher non-cultivated plant diversity, encourage the use of agricultural areas by migrating birds. We found that cropland is used as stopover habitat by bird species that can utilize a large breadth of habitats, as well as species with preferences for habitat similar in structure to agricultural areas.

A Qualitative Study of Ecstasy Sellers in the San Francisco Bay Area

2004 ◽  
Author(s):  
Sheigla Murphy ◽  
Paloma Sales ◽  
Micheline Duterte ◽  
Camille Jacinto
Keyword(s):  
Qualitative Study ◽  
San Francisco ◽  
San Francisco Bay ◽  
San Francisco Bay Area ◽  
Bay Area

Cyborg Jotería Pedagogies: Latinx Drag Queens Leveraging Communication Ecologies in the Age of the Digital and Social Displacement

2020 ◽  
Vol 14 (2) ◽  
pp. 44-66
Author(s):  
José Ramón Lizárraga ◽  
Arturo Cortez
Keyword(s):  
San Francisco ◽  
San Francisco Bay ◽  
San Francisco Bay Area ◽  
Digital Technologies ◽  
Physical World ◽  
Political Issues ◽  
Drag Queen ◽  
Bay Area ◽  
Online Presence ◽  
Drag Queens

Researchers and practitioners have much to learn from drag queens, specifically Latinx queens, as they leverage everyday queerness and brownness in ways that contribute to pedagogy locally and globally, individually and collectively. Drawing on previous work examining the digital queer gestures of drag queen educators (Lizárraga & Cortez, 2019), this essay explores how non-dominant people that exist and fluctuate in the in-between of boundaries of gender, race, sexuality, the physical, and the virtual provide pedagogical overtures for imagining and organizing for new possible futures that are equitable and just. Further animated by Donna Haraway’s (2006) influential feminist post-humanist work, we interrogate how Latinx drag queens as cyborgs use digital technologies to enhance their craft and engage in powerful pedagogical moves. This essay draws from robust analyses of the digital presence of and interviews with two Latinx drag queens in the San Francisco Bay Area, as well as the online presence of a Xicanx doggie drag queen named RuPawl. Our participants actively drew on their liminality to provoke and mobilize communities around socio-political issues. In this regard, we see them engaging in transformative public cyborg jotería pedagogies that are made visible and historicized in the digital and physical world.

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