bluuebunny/crossref_metadata_2025 huggingface dataset:
Workers’ Health in Latin America and the Caribbean
Authors: Mendes René
Published: October 2019

In different countries and regions of the world—particularly in Latin America and the Caribbean—the term “workers’ health” may have different meanings. From a more traditional perspective, defined on economic and demographic bases, this term introduces a delimitation characterized by economically active people, usually over 10 years of age, of both sexes, and who are working, have worked at some point in their life, or are in search of work. This condition usually ceases in case of retirement or disability. Such a criterion, as can be imagined, is extremely imprecise, particularly in regions such as the ones analyzed here, since it includes great variability of situations, including work considered informal; the work of children and adolescents (prohibited or restricted in accordance with international labor standards); clandestine and illegal work; domestic work (sometimes not formally recognized); and slave and forced labor. It is not clear, either, when work activity actually ceases, especially when there are no social protection systems for elderly and disabled people. But even if this definition is adopted, it is already possible to foresee the complexity of the theme, both in the conceptual perspective and in the scope of health programs, as well as in the health and illness problems of this population.

However, in some countries, the term “workers’ health” (or “worker’s health”) goes beyond the economic or demographic delimitation, and includes a paradigm shift about the role of workers in the struggle for their health. This perspective, political and ideological, originates in the concepts and experience of the “Italian Labor Model”; brings in elements of the Marxist discourses and Liberation Theology; takes advantage of and improves the perspective of “Social Epidemiology” or “Social Medicine”; and, in our continent, can be considered as an unfolding of “Latin American Social Epidemiology.” This understanding of workers’ health also depends on social movements—such as unions and other forms of organizing workers—as well as on political leaders committed to the struggle of workers against precarious work, unemployment and the destruction of already established social rights, especially in the context of neoliberalism.

Therefore, workers’ health is a polysemic and complex concept, and its discussion is a living, dynamic, and extremely rich agenda.
William Seward and the Diplomacy of the Civil War
Authors: Randolph Stephen P.
Published: October 2019

Best known as Abraham Lincoln’s secretary of state during the Civil War, William Henry Seward conducted full careers as a statesman, politician, and visionary of America’s future, both before and after that traumatic conflict. His greatest legacy, however, lay in his service as the secretary of state, leading the diplomatic effort to prevent European intervention in the conflict. His success in that effort marked the margin between the salvation and the destruction of the Union. Beyond his role as diplomat, Seward’s signature qualities of energy, optimism, ambition, and opportunism enabled him to assume a role in the Lincoln administration extending well beyond his diplomatic role as the secretary of state. Those same qualities secured a close working relationship with the president as Seward overcame a rocky first few weeks in office to become Lincoln’s confidant and sounding board.

Seward’s career in politics stretched from the 1830s until 1869. Through that time, he maintained a vision of a United States of America built on opportunity and free labor, powered by government’s active role in internal improvement and education. He foresaw a nation fated to expand across the continent and overseas, with expansion occurring peacefully as a result of American industrial and economic strength and its model of government. During his second term as secretary of state, under the Johnson administration, Seward attempted a series of territorial acquisitions in the Caribbean, the Pacific, and on the North American continent. The state of the post-war nation and its fractious politics precluded success in most of these attempts, but Seward was successful in negotiating and securing Congressional ratification of the purchase of Alaska in 1867. In addition, Seward pursued a series of policies establishing paths followed later by US diplomats, including the open door in China and the acquisition of Hawaii and US naval bases in the Caribbean.
The Third World and the United States
Authors: Ewing Cindy
Published: October 2019

The concept of the Third World emerged after 1945 as a way to refer to the developing regions of the world, most often encompassing Africa, Asia, the Middle East, and Latin America. As a descriptive shorthand, the Third World entered common usage to contrast these regions from the capitalist “First World” and the communist “Second World,” even though some nations in these regions overtly aligned with one of the superpowers while others did not ascribe to such classifications. The term thus defies easy categorization and was used by historical actors to reflect different political and economic understandings of their geopolitical status. In the latter half of the 20th century, the Third World also gained purchase among some political leaders to describe non-Western, anti-imperialist, and anti-racist nations that had gained their independence from colonial rule and worked together to resist Cold War alignment. However, Third World leaders struggled to sustain their transnational solidarity, sometimes dividing along the lines of the broader superpower rivalry, regional or sectarian conflicts, and differing aspirations for world order.

US relations with the Third World were often fraught and complex. The United States did not maintain a single policy toward the Third World as such, reflective of its enormous diversity in language, culture, and politics. Instead, the United States devised foreign policies toward Third World nations according to different perceived imperatives and interests. A major theme in the history of US relations with the Third World was the US government’s overarching effort after World War II to undermine the spread of international communism, against which it deployed a wide range of military, political, social, and economic tools. In kind, Third World political leaders often strove to evade direct control by the United States and entered into diplomatic relations cognizant of the power asymmetries at work in the international system. In the 21st century, scholars and policymakers continue to use the Third World term, though it is often used interchangeably with the Global South and the underdeveloped, developing, and non-Western world.
Slavery and the Pursuit of Freedom in 16th-Century Santo Domingo
Authors: Turits Richard Lee
Published: October 2019

In the past, scholars of Latin America often assumed that Spanish colonists abandoned the Caribbean for the bullion riches of Mexico and Peru almost immediately after their conquest, while many Caribbeanists have imagined that Barbados, colonized by the British in the mid-1600s, was the “first black slave society.” Yet, in fact, more than a century earlier in the colony of Santo Domingo (then officially known as la Isla Española or simply la Española), European colonists built the first major American plantation economy and society made up mostly of enslaved people. Those held in chains on the island reached into the tens of thousands by the mid-1500s, and Santo Domingo became a pivotal crossroads in the early modern Atlantic. At first the enslaved population included thousands of people the Spanish called “Indians,” taken from other parts of the Caribbean and the Americas, and even an occasional enslaved person of European (Orthodox Christian or Muslim) descent. But after the mid-1500s slavery in Santo Domingo became isolated to people of African descent. This contrasted with the preexisting demography of slavery in southern Europe, where the enslaved were of more diverse geographic origins. Santo Domingo thus initiated a trajectory of racial and plantation slavery whose contours would shape the course of history in the Americas overall. Santo Domingo’s slave-based economy would also, though, be the first to collapse, at the end of the 16th century, partly because of sustained resistance by the enslaved—their continual escape and rebellion—that was costly for planters. The enslaved had composed most of society in the prior century. Now the majority were escaped and, to a lesser extent, freed slaves, living with substantial autonomy as independent peasants dispersed across the countryside. These themes are illuminated through an exploration of one of the earliest freedom suits in the Americas. This suit was won on appeal in Santo Domingo in 1531 through remarkable transatlantic collaboration by family members and sailors as well as through the evident power of notarized documents in the Spanish Empire.
Maps, Power, and the Pacification of La Araucanía-Chile, 1850–1900
Authors: Fernández Pablo Azócar , Maldonado Zenobio Saldivia
Published: October 2019

In the history of cartography and in critical cartography, there is a link between the role of maps and power relations, especially during the conquest and domination of territories by national states. Such cartographic products have frequently been used—for both their scientific and persuasive content—in different places, such as in Chile in the Araucanía region during the so-called pacification process, led by the Chilean state during the second half of the 19th century. From a cartographic perspective, the “epistemological and unintentional silences on the maps” can be observed for maps produced during this process. It implied that the “scientific discourse” and the “social and political discourse” of the cartographic images generated during this process of conquest and domination were relevant for the expansionist objectives of the Republic of Chile.
Morphology and Language Attrition
Authors: Montrul Silvina , Yoon James
Published: October 2019

Language attrition is the loss of linguistic abilities or the regression of specific grammatical properties and overall fluency in linguistic skills. It impacts language use, lexical access, and grammatical integrity. Non-pathological attrition is natural in situations of language contact and bilingualism and can occur in the first, native, language as well as in a second language. As a gradual and dynamic process of accommodation that occurs when bilinguals use the second language extensively, attrition is a highly individualized phenomenon and hard to predict a priori. If attrition eventually happens, it affects individuals differently, with some exhibiting more widespread loss than others. Two factors that determine the extent of language attrition in bilinguals are the availability of input and the age of the individual at the onset of the reduction in input in their native language. An important question is whether attrition mainly occurs at the level of processing or whether it affects actual linguistic competence. Theoretical approaches to attrition have emphasized its relationship with L1 acquisition, the selectivity of attrition by linguistic modules, the effects of language use on memory, and the interplay between the L1 and the L2 along the life span. We still lack understanding of how attrition affects linguistic representations and processing and the external and individual cognitive factors that modulate, predict, or prevent attrition in bilinguals.

Morphological attrition is far more common and extensive in children than in adults and it manifests itself in a variety of ways: morphophonemic leveling, morphological simplification, including omission of required morphology in obligatory contexts, paradigmatic reduction, simplification/reduction of suffixal allomorphy, regularization of irregular forms, and the replacement of synthetic forms for analytic/periphrastic forms. Morphological attrition has often been discussed in the context of language death and language loss at the community level for both child and adult bilinguals. The scant empirical evidence to date seems to indicate that the processes of omission, regularization, and suppletion that are common in attrition occur regardless of the dominant morphological type of a language. Both inflectional and derivational morphology are affected under language attrition and seem to undergo similar processes of reduction and simplification, regardless of the morphological type of the language. Within inflectional morphology, nominal morphology (gender, number, case) is more prone to attrition in the actual number of occurrences than verbal morphology (agreement, tense, aspect, mood), and attrition occurs more rapidly and extensively.
Machinations of the British Medical Association: Excluding Refugee Doctors from Queensland’s Medical Profession, 1937–1942
Authors: Wolf Gabrielle
Published: October 2019

When medical practitioners fled from the Nazi regime in the 1930s, the British Medical Association (hereafter BMA), the representative body of the medical profession in the British Empire, agitated strenuously to prevent ‘refugee doctors’, as they were described, from practising medicine throughout the Empire. Prominent BMA representatives pursued this agenda in Australia through their appointment to statutory state-based authorities that registered and regulated doctors'. This article investigates how, between 1937 and 1942, they sought to use those bodies’ registration and disciplinary powers in Queensland to exclude refugee doctors. They were particularly persistent in this state given its government's resistance to BMA pressure to pass legislation restricting refugee doctors’ eligibility for registration. In so doing, the article contributes new perspectives to scholarship that analyses the BMA’s effectiveness as a pressure group. This article’s exploration of motives for the BMA’s animosity towards refugee doctors also builds on histories of the medical profession and of ethnicity within it.
Geographic Variation in Habitat Structure of the Black-Throated Green Warbler (Dendroica virens)
Authors: Collins Scott L.
Published: October 2019

Habitat structure of the Black-throated Green Warbler (Dendroica virens) was examined at five study sites: (1) Mount Desert Island, Maine; (2) Mount Blue State Park, Maine; (3) White Mountain National Forest, New Hampshire; (4) southern Adirondacks, New York; and (5) Itasca State Park, Minnesota. Principal component analysis of 13 habitat-structure variables measured at each site produced habitat gradients from tall to shorter canopies, large to smaller trees, and coniferous to deciduous forests. A second ordination indicated that the habitat sampled included five plant-community types: pine forests, spruce-arbor vitae, balsam fir, mixed spruce-fir-deciduous, and beech-maple-birch. Consistent structural features within the total range of habitats sampled were difficult to identify. I suggest that widely occurring species such as the Black-throated Green Warbler have a wide range of habitats with a suitable structure and that regional analyses, even within a single plant-community type, may be of limited value with regard to habitat management when considering the entire range of many species.
The Structure of Aerial Displays in Three Species of Calidridinae (Scolopacidae)
Authors: Miller Edward H.
Published: October 2019

Sandpipers in the subfamily Calidridinae (Scolopacidae) breed in the Arctic and Subarctic. In all species, unpaired males engage in distinctive aerial displays. Such displays are described for three species: Dunlin (Calidris alpina L.), Semipalmated Sandpiper (Calidris pusilla L.), and Stilt Sandpiper (Calidris himantopus Bonaparte). In each of the species, displays last several minutes, during which simple monotonous calls are emitted; more complex calls (including "song") also occur. C. himantopus has a unique flight mode, which is considered as apomorphous (derived) within the subfamily. C. alpina is apomorphous for the buzziness of the main vocalization emitted in aerial display and C. pusilla for loss of the same vocalization and elaboration of another. The ancestral/derived status and systematic value of these and other display components are discussed, with reference to information available for other calidridine species.
Generalization of and Effects of Pre-Exposure on Color-Avoidance Learning by Red-Winged Blackbirds (Agelaius phoeniceus)
Authors: Mason J. Russell , Reidinger Russell F.
Published: October 2019

We report two experiments designed to assess whether quality of color (and shades) influences food-aversion learning by Red-winged Blackbirds (Agelaius phoeniceus). In Experiment 1, Red-wings were given food paired with one of two shades of red or green followed by toxicant-induced sickness. In subsequent tests for generalization of the learned aversions, avoidance of red was generalized broadly to other shades of red, whereas avoidance of green appeared to be relatively stimulus specific. In Experiment 2, we pre-exposed Red-wings to a single shade of red or green in a feeding context for 4 days. Then the birds were conditioned as in Experiment 1 and tested for expression of learned color aversions. Although pre-exposure weakened expression of aversions to both colors, such effects were more pronounced for green. The effects were greater for birds pre-exposed to the conditioning color in close association with the food than for birds pre-exposed to the conditioning color away from food. Generalization of conditioned aversions and resistance to the effects of pre-exposure may reflect adaptations of Red-wings for prey selection. It would appear adaptive for birds to generalize avoidance learning broadly for conspicuously colored, noxious prey and to exhibit such learning regardless of prior experience with the color. Conversely, because few cryptically colored (e.g. green) prey are noxious, it would be adaptive for learning to be specific for the noxious individuals alone. Finally, we believe that the generalization of learned aversions could serve as a useful criterion in selecting appropriate color stimuli for use in bird control (i.e. repellency) and that the methods presented here could provide one empirical means of assessing such generalizations.
Parasitic Egg Laying in Redheads and Ruddy Ducks in Utah: Incidence and Success
Authors: Joyner David E.
Published: October 2019

North American Ruddy Ducks (Oxyura jamaicensis) and Redheads (Aythya americana) lay eggs parasitically in other waterfowl nests. Interspecific egg parasitism at Farmington Bay Waterfowl Management Area (WMA), Utah during 1972-1974 affected 290 (36%) of 809 duck nests. Redheads deposited 812 eggs into 264 nests of other species, whereas Ruddy Ducks deposited 146 eggs into 62 nests. Of 620 Redhead eggs deposited interspecifically and for which success rates were known, 21% hatched, compared with 24% of 146 Ruddy Duck eggs. Forty-three percent of the Redheads and 7% of the Ruddy Ducks produced on the study site hatched from eggs deposited interspecifically. An unknown number of Redhead and Ruddy ducklings hatched from eggs deposited intraspecifically. Rates of egg parasitism in Redheads and Ruddy Ducks did not increase in response to severe fluctuations in water levels affecting habitat used by nesting waterfowl, nor was a lack of suitable nesting cover associated with Redhead or Ruddy Duck parasitism. These results counter the contention that parasitic tendencies in the Redhead, and perhaps the Ruddy Duck, are environmentally induced.
Factors Affecting the Distribution of Mallards Wintering in the Mississippi Alluvial Valley
Authors: Nichols James D. , Reinecke Kenneth J. , Hines James E.
Published: October 2019

The Mississippi Alluvial Valley (MAV) is the principal wintering area for Mallards (Anas platyrhynchos) in the Mississippi Flyway. Here, we consider it a distinct habitat (sensu Fretwell 1972), i.e. fitness is relatively homogeneous among ducks within the MAV but different from that of ducks in other such habitats. We analyzed recovery distributions of Mallards banded preseason (July-September 1950-1980) to test hypotheses concerning the effects of winter temperatures, precipitation, and population levels on Mallard winter distribution. When two groups of years that comprised extremes of warm and cold winter weather were compared, recovery distributions of all four age and sex classes (adult males and females, young males and females) differed significantly; recoveries were located farther south in cold years. Recovery distributions also differed between wet and dry years in the MAV for all groups except adult males, higher proportions of recoveries of adult females and of young males and females occurring in the MAV during wet winters. Although differences in continental Mallard population size were associated with differences in recovery distributions only of adult males and young females, the proportion of young males and of all young Mallards recovered in the MAV increased during years of low populations. We conclude that temperature, water conditions, and population size affect the habitat suitability of Mallard wintering areas and that Mallards exhibit considerable flexibility in winter distribution associated with these factors.
The Role of Plumage Polymorphism in Dominance Relationships of the White-throated Sparrow
Authors: Watt Doris J. , Ralph C. John , Atkinson Carter T.
Published: October 2019

We studied dominance behaviors of captive winter flocks of White-throated Sparrows (Zonotrichia albicollis) in central Pennsylvania. Preliminary tests with a small group of birds indicated that there might be differences in behaviors between color morphs if age and sexual differences were controlled. Studies of two larger groups produced considerable variation in results between the groups. One group displayed striking correlations between dominance ability and color. In this group white adult males dominated others more than tan adult males did, whereas tan immature males, adult females, and immature females were more often dominant than were white immature and female birds. The second group did not display such striking differences. Tan adult and immature females were more dominant than white females, as in the first group, but not significantly. Immature males displayed the opposite trend from the first group-white morphs were more dominant than tans. Adult males in the second group showed no clear trend. We also found differences in dominance between tan and white females that appeared to depend on season, white birds dominating tan birds in a small group in the spring, a reversal of relationships documented in the fall. Within age-sex classes, dominant females in both large groups tended to be duller in plumage brightness (scaled as an index) than were subordinate females. In one of the two large groups, duller immature males were more dominant than brighter ones, while brighter adult males tended to be more dominant than duller ones. We suggest that the relationships between immature male plumage and dominance may be influenced by the morph of adult males of specific dominance status in the flock. Spring plumage indices were more often correlated with fall dominance differences than were fall plumage conditions, suggesting a genetic or causal relationship between dominance and plumage rather than a proximate (status signaling) function. Recorded morph frequencies from this study and the literature support the hypothesis that selection is balanced between the two morphs and is dependent on the advantages or disadvantages of aggressiveness within a sex.
Feeding Schedule and Daily Food Consumption in Red-Throated Loons (Gavia stellata) over the Prefledging Period
Authors: Reimchen T. E. , Douglas Sheila
Published: October 2019

We describe parental feeding activities of Red-throated Loons (Gavia stellata) throughout the prefledging period at two freshwater nesting territories in coastal British Columbia. The nesting lake contained resident fish populations, but adult loons fed marine fish to their young, making an average of 11 flights per day (average duration 60 min per flight) to the ocean and returning each time with a single fish. Small shallow-bodied fish (Ammodytidae, Pholidae), which were easily swallowed by chicks, predominated in the diet during the 3 days following hatching. The total weight of fish fed to the chicks per day (8-194 g) increased over the prefledging period: adults returned fewer but larger fish (Embiotocidae) as the chick aged. Of the fish offered, 4% were too large for the chick to swallow.
The Effect of Temperature and Clutch Size on the Energetic Cost of Incubation in a Free-Living Blue Tit (Parus caeruleus)
Authors: Haftorn Svein , Reinertsen Randi Eidsmo
Published: October 2019

The energetic cost of incubation of a free-living Blue Tit (Parus caeruleus) female was studied during two breeding seasons by measuring the rate of oxygen consumption in a nest box converted into a metabolic chamber. Like its congeners, only the female Blue Tit incubates and during that time is fed by the male. Just before and during the egg-laying period the female spends the night in the nest. Because of the progressive development of incubation behavior during this period, it is possible to measure the oxygen-consumption rate of a nonincubating female (resting metabolism) and to compare it with values obtained later when the bird is incubating a full clutch under otherwise similar conditions. The air temperature in the metabolic chamber was regulated experimentally. The results show that the energy cost of incubation is relatively important below the lower critical temperature (about 15°C). With a fall in the air temperature, energy expenditure increased in relation to that of the resting metabolism. The energy cost of incubation also increased with clutch size, by about 6-7% for each additional egg. At air temperatures around 0°C, which are frequent under natural conditions in Fennoscandia, the female must increase her metabolic rate by 50-90% to keep the eggs in a normal-size clutch (10-13 eggs) warm. During the last days of incubation we accounted for the metabolism of the embryos, which on the day before hatching contributed about 15% of the total oxygen consumption when the female was incubating a clutch of 13 eggs.
Comparative Reproductive Success of Yellow-Shafted, Red-Shafted, and Hybrid Flickers across a Hybrid Zone
Authors: Moore William S. , Koenig Walter D.
Published: October 2019

Alternative hypotheses of hybrid zones make specific predictions about reproductive components of fitness in the hybrids. The dynamic-equilibrium and reinforcement hypotheses are premised on reduced hybrid fitness, which should be apparent as reduced clutch or brood size or as increased embryonic mortality. The hybrid-superiority and introgression hypotheses predict normal clutch and brood size and embryonic mortality.

Reproductive success was measured at four study sites on a transect across the hybrid zone between the Yellow- (Colaptes auratus auratus) and Red-shafted (C. a. cafer) subspecies of the Northern Flicker. Two additional clutch size samples representing pure Yellow- and Red-shafted flickers were obtained from museum egg collections. Mean clutch size did not differ significantly among the six samples. Factorial ANOVAs showed that early clutches and broods are larger than late clutches and broods, but no significant difference was detected between hybrid and parental study sites. Analyses of the effect of phenotype (yellow-shafted, red-shafted, hybrid) also suggest that neither clutch size nor brood size is affected, with the exception that hybrid males sired significantly smaller broods. Finally, there were no significant effects of type of cross (red-shafted male × hybrid female, etc.) on the ratio brood-size/clutch-size.

The only evidence for reduced hybrid fitness was in the test where males with hybrid phenotypes appear to have sired small broods. This may indicate that abnormal behavior of hybrid males affects female fecundity, but it is also plausible that this marginally significant result is a type I statistical error. The overall lack of evidence for reduced hybrid fitness is inconsistent with either the dynamic-equilibrium or reinforcement models. Of the two remaining alternatives, the bounded hybrid-superiority model appears the more likely explanation of the Northern Flicker hybrid zone because earlier work (Moore and Buchanan 1985) showed that the hybrid zone is not becoming broader, as predicted by the introgression model.
Reversed Sexual Size Dimorphism: Effect on Resource Defense and Foraging Behaviors of Nonbreeding Northern Harriers
Authors: Temeles Ethan J.
Published: October 2019

Sexual differences in resource defense and foraging behaviors during the nonbreeding season are detailed for Northern Harriers (Circus cyaneus) in California. Female harriers hunted more frequently in high (>0.5 m) vegetation than males. In addition, females hunted at slower speeds and used different hunting behaviors than males. Females in high vegetation showed a significantly greater response (i.e. attack) rate to approaching harriers than males, and females won nearly all (28/29) aggressive interactions with males. These results suggest that sexual differences in harrier foraging behavior during the nonbreeding season result from females excluding males from preferred foraging areas and males adopting alternative foraging strategies. Foraging strategies of harrier sexes are compared with foraging strategies of sexes of birds in which males are larger than females to examine the role of body size in determining sexual foraging strategies.
Density Trends and Range Boundary Constraints of Forest Birds Along a Latitudinal Gradient
Authors: Emlen John T. , DeJong Michael J. , Jaeger Michael John , Moermond Timothy C. , Rusterholz Kurt A. , White Robin P.
Published: October 2019

We plotted the density distributions of 41 land-bird species along a 1,200-km transect spanning 7°28′ (865 km) of latitude through relatively uniform bottomland deciduous forest in middle North America. Standardized counts and observations at 12 survey stations, closely matched in habitat structure and widely distributed along the route, provided population data for all species and indices of total avian foraging pressure (consuming biomass) on each of six major foraging substrates.

Density curves for species fluctuated considerably from station to station but tended to be level across range centers and slope peripherally to north and south boundaries at rates of 3-30% per degree of latitude. Substrate foraging pressures declined northward on the aerial and midfoliage substrates and southward on the low-foliage substrate. Summed community densities showed no significant latitudinal trends.

We used the distinctive distribution patterns of climate (smooth latitudinal gradients), habitat structure (irregular mosaics of vegetation patches), and competition (reciprocally sloping density gradients) to identify and evaluate the role of these three constraints along the transect. Progressive latitudinal trends in species abundance thus were attributed to climatic factors, irregular station-to-station fluctuations to habitat factors, and inversely sloping density trends in paired profiles to competition. On this basis all species apparently responded to both climatic and habitat factors, and about half of the species showed suggestions of competition. In a correlation analysis across the 12 stations, latitude per se most closely matched density distribution in 12 species, one or another of the habitat parameters in 25 species. We proposed that season length (days available for breeding activity) was the principal constraining attribute of latitude at northern range boundaries, day length (hours available for feeding and provisioning young) at southern boundaries.

Boundaries have been essentially stable during the past 50-100 yr in most species, but the northern boundary expanded northward in one species following human-induced habitat enhancement, and temporarily receded southward in another following a winter of severe stress. We attribute this general stability of range boundaries over time to within-population gene flow and the associated peripherally declining mean fitness of phenotypes adapted to central range conditions along radially diverging environmental gradients.

We suggest that two boundary lines should be recognized for each species, an inner functional boundary at the line where birth rates drop below death rates, and an outer empirical boundary at the limit of recorded occurrences.
Differences in Sexual Size Dimorphism and Body Proportions between Adult and Subadult House Sparrows in North America
Authors: McGillivray W. Bruce , Johnston Richard F.
Published: October 2019

North American samples of House Sparrows (Passer domesticus) collected by R. F. Johnston and R. K. Selander (see Johnston and Selander 1971, Johnston 1973) were separated into adult (19 localities) and subadult (21 localities) groups. Significant clines were generated for all age and sex combinations through regression of locality means for body size against environmental seasonality. The strong body-size clines for subadult House Sparrows suggest a large genetic component to geographic variation in House Sparrow body size. There were no significant differences between the male and female clines for either age group. Therefore, there was no consistent relationship between sexual size dimorphism (SSD) in adult House Sparrow populations and environmental factors. Adult levels of SSD were higher than subadult levels at localities with distinct seasonalities. This resulted from selection against relatively large subadult females in areas with cold winters. Adult males were larger than subadult males, but whether this represented growth or selection is equivocal. The ratio of body core to limb variables was correlated poorly with the winter temperatures of the collecting localities.

The relationship improved if samples from coastal areas were excluded. Adult levels of this ratio were higher than subadult levels at localities with low January temperatures. Overwinter changes in both House Sparrow size and shape can be correlated with environmental variables. Although selection for efficient thermoregulatory design is implied, it is difficult to account for the mortality of large subadult females over cold winters and to completely discount the effects of growth.
Habitat Use by Wading Birds in a Subtropical Estuary: Implications of Hydrography
Authors: Powell George V. N.
Published: October 2019

The dynamics of foraging habitat use by long-legged wading birds was analyzed with respect to water-level fluctuation patterns in Florida Bay. Wading-bird presence at four sites situated to sample the heterogeneity of the bay was quantified by repeated surveys collected throughout the day and year. Models for habitat availability were generated using water-level data collected from continuous recorders, staff guages, and habitat profile maps. These models were tested against the survey data.

Roseate Spoonbills (Ajaia ajaja) foraged on the study areas primarily at night. Great Blue Herons (Ardea herodias) fed both day and night, but primarily at night where the tidal range was small. Great Egrets (Casmerodius albus), Snowy (Egretta thula) and Reddish (E. rufescens) egrets, Little Blue (E. caerulea) and Tricolored (E. tricolor) herons, and White Ibis (Eudocimus albus) fed during daylight. Where tidal range was small (<5 cm) diurnal species fed throughout the day.

Florida Bay has a pronounced annual water-level cycle that causes monthly mean water levels to vary by as much as 30 cm between October (high) and May (low). Models derived from hydrology data predicted that this seasonal variation in water level would have a major impact on habitat availability, particularly where tidal flux was small. The predictions were supported by survey data. At sites with minor tides, most wading-bird species had a cycle in seasonal abundance that correlated with seasonal changes in water level; only the tallest species, Ardea herodias, was uniformly present throughout the year. The large daily range in tide (x̄ = 80 cm) afforded year-round access to foraging habitat, and these abundance patterns did not exist. The seasonal variability in habitat availability has major management implications because the maintenance of stable wading-bird populations depends on the availability of alternative foraging sites when water levels are high. Historically, these sites have tended to be targeted for human development.
Effects of Food Supplementation, Song Playback, and Temperature on Vocal Territorial Behavior of Carolina Wrens
Authors: Strain Joy G. , Mumme Ronald L.
Published: October 2019

We found both the song rate and the rate of song-type change of male Carolina Wrens (Thryothorus ludovicianus) in winter were positively correlated with ambient temperature. When the effect of temperature was controlled statistically, food supplementation significantly increased both the song rate and the rate of song-type change. Song playback did not significantly increase either song rate or rate of song-type change, however. Because foraging and singing are mutually exclusive behaviors in Carolina Wrens, the increase in vocal territorial behavior associated with warmer temperatures and food supplementation may reflect a decrease in the time required for foraging. The rate of vocal territorial behavior in winter may be more dependent on the amount of food available to wrens than on the presence of intruders.
Evidence Against Observational Learning in Storage and Recovery of Seeds by Black-Capped Chickadees
Authors: Baker Myron Charles , Stone Eric , Baker Ann Eileen Miller , Shelden Robert J. , Skillicorn Patricia , Mantych Mark D.
Published: October 2019

Recovery of cached sunflower seeds by Black-capped Chickadees (Parus atricapillus) was observed in four laboratory experiments. Results of the first experiment were consistent with the hypothesis that chickadees use spatial memory to recover seeds cached 24 h earlier. The second experiment demonstrated that individuals have a high recovery rate for their own caches and a low recovery rate for caches made by another. The third and fourth experiments demonstrated that one chickadee observing another caching seeds provided no recovery benefit to the observer in comparison to its performance when recovering seeds hidden in its absence. This result held for 2-h and for 6-min delays between observation and attempted recovery. We believe that spatial memory is used by chickadees, that the individual carrying out the caching has a large recovery advantage over a conspecific that searches the same patch, and that the perceptual and motor experience involved in the act of traveling to a cache location may be necessary for the establishment of spatial memory.
Red Color Bands Reduce Fledging Success in Red-Cockaded Woodpeckers
Authors: Hagan John M. , Reed J. Michael
Published: October 2019

An analysis of the effects of colored leg bands on Red-cockaded Woodpeckers, in a long-term field study, showed that males that wore red bands fledged significantly fewer young than males without red bands. Other colors were unrelated to fledging success. Band color had no detectable effect on the fledging success of adult females. The offspring sex ratio of breeding males wearing red bands was significantly female-biased. Offspring sex ratios were not related to the presence or absence of red bands on breeding females. Wearing a red band did not affect the probability of a male attracting a mate or the probability of switching mates. For both sexes, annual age-specific survival was independent of the presence or absence of a red band, but nestlings wearing red bands were less likely to be sighted as fledglings. Males with red bands fledged fewer young, consistent with both the species-recognition hypothesis and the coverable-badge hypothesis. The coverable-badge hypothesis, which predicts that the inability to conceal a voluntary social signal (the red cockade) can be detrimental, is the more parsimonious explanation of our results.
Adjustment of Parental Investment with Mate Quality by Male Yellow-Headed Blackbirds (Xanthocephalus xanthocephalus)
Authors: Gori David F.
Published: October 2019

By removing young from the nests of competent females, I tested whether male Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) could assess the parental competence of mates and adjust their parental investment accordingly. The purpose of this experimental reduction was to equalize the number of young in nests of parentally competent and incompetent females in order to control for the effect of offspring number on parental investment by males. Males had a greater probability of feeding at nests of competent-reduced females and they fed at a higher rate than they did at nests of incompetent females. The latter broods were fed only when nests belonging to competent females were unavailable. Males adjust their parental investment with mate quality independent of the number of young in nests. To explain this preference, I constructed functions to relate the amount of paternal investment (i.e. male feeding rate) to the number of young fledged from nests and the fledging mass of young. The latter are two components of male reproductive success and, therefore, estimates of the "return" on a male's parental investment. Male feeding had no effect on the number of young fledged from starvation-reduced or experimental nests. However, the fledging mass of young increased more when males helped competent females than when incompetent females were helped. Thus male preference for helping competent females may result because the return per unit of their investment is greater at these nests.
Early Growth and Development of the Common Barn-Owl's Facial Ruff
Authors: Haresign Tim , Moiseff Andrew
Published: October 2019

The ability of the Common Barn-Owl (Tyto alba) to localize sounds produced by potential prey can be explained on the basis of sensitivity to differences in interaural time and intensity. The size of the owl's head is a prime determinant of interaural time differences, whereas the facial ruff is the prime determinant of interaural intensity differences. During the 60 days following hatching, the physical structures that establish these binaural cues undergo massive growth. Barn-owl chicks are altricial and scantily feathered when they hatch. Growth of the head and ruff feathers occur at separate times during early maturation. Between 11 and 30 days after hatching, the diameter of the head approximately doubles. Between 35 and 60 days, facial ruff feathers emerge and grow to nearly adult length (ca. 20 mm). During the first 60 days of life, the barn-owl auditory system would be subject to widely varying binaural cues which eventually stabilize.
The Costs and Benefits of Egg Destruction by Conspecifics in Colonial Cliff Swallows
Authors: Brown Charles R. , Brown Mary Bomberger
Published: October 2019

We studied egg destruction by conspecifics in colonial Cliff Swallows (Hirundo pyrrhonota) in southwestern Nebraska. Between 8.5% and 19.6% of all nests lost at least 1 egg to an intruding conspecific. Egg destruction occurred when nests were left momentarily unattended, often during colony alarm responses. Birds that destroyed eggs maintained nests of their own, and usually nested within 75 cm of their victims. Egg destruction was not related to attempts to usurp nests. Over a third of perpetrators of egg destruction lost eggs from their own nests to conspecifics. Egg destruction occurred more often in nests initiated early in the nesting season and in nests with large clutch sizes. Egg destruction usually occurred during a victim's egg-laying or early during incubation and declined in frequency as incubation proceeded. Breeding in a colony's peak period of nesting did not afford an advantage to potential victims by diluting their chances of being victimized. Cliff Swallows seldom destroyed all of the eggs in a neighbor's clutch, usually destroying only 1 egg at a time even though other eggs were present.

There was little direct evidence that egg destruction was associated with parasitic egg-laying by Cliff Swallows, but nests with egg destruction were over 3 times more likely than nests in general to have an egg physically transferred into them. The costs of egg destruction to victims were obvious, but the benefits to destroyers of eggs were not. Egg destruction is possibly a prelude to physical transfer of eggs, reducing host clutch sizes and ultimately within-brood competition among host and parasitic nestlings. Males may also benefit by destroying a female's eggs during laying, thereby causing her to continue laying and remain sexually receptive to forced extrapair copulations. Incidence of egg destruction by conspecifics increased with Cliff Swallow colony size and thus, for potential victims, represents a definite cost of coloniality.
Assessing Population Trends of New Hampshire Forest Birds: Local vs. Regional Patterns
Authors: Holmes Richard T. , Sherry Thomas W.
Published: October 2019

We examined the changes in abundance between 1969 and 1986 of 19 forest-dwelling, mostly migratory bird species breeding in New Hampshire at 2 different scales: one local (an intensively studied 10-ha plot in unfragmented forest) and the other regional (Breeding Bird Surveys statewide). Twelve of the 19 species exhibited similar trends at both scales. Eight neither increased nor decreased, and 4 (Least Flycatcher, Winter Wren, Wood Thrush, and Swainson's Thrush) declined significantly. Others increased, decreased, or remained steady at one or the other scale. Overall, more species declined than increased both locally (8 vs. 1) and regionally (5 vs. 1). Comparisons of these patterns, combined with results of intensive studies at the local level, suggest that changes in food abundance and in vegetation structure related to forest succession on the breeding grounds, along with other processes that influence bird reproductive success and survivorship, are the most plausible explanations for most of the observed trends. Winter mortality was also identified as affecting breeding abundances, but only in short-distance migrant and permanently resident species. We have no evidence to indicate that the numbers of long-distance migrants were affected by events in their Neotropical wintering areas, although this possibility is difficult to assess from breeding-ground data. We urge caution in attributing declines of breeding forest migrant birds to tropical deforestation or similar causes until we either can eliminate alternate explanations that involve breeding-season events or have available critically needed demographic information on migrant populations in their wintering areas.