bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accuracy monism and doxastic dominance: reply to Steinberger
Authors: Hewson Matthew 
Published: October 2019

Abstract
Given the standard dominance conditions used in accuracy theories for outright belief, epistemologists must invoke epistemic conservatism if they are to avoid licensing belief in both a proposition and its negation. In ‘Accuracy and epistemic conservatism’ Florian Steinberger charges the committed accuracy monist – the theorist who thinks that the only epistemic value is accuracy – with being unable to motivate this conservatism. I show that the accuracy monist can avoid Steinberger’s charge by moving to a subtly different set of dominance conditions. Having done so, they no longer need to invoke conservatism. I briefly explore some ramifications of this shift.
Frugivory and Polygamy in Birds of Paradise
Authors: Beehler Bruce 
Published: October 2019

Abstract
I studied fruit-feeding by nine species of birds of paradise in Papua New Guinea from July 1978 through November 1980 and gathered 1,187 records of foraging at 31 species of trees and vines from 14 botanical families. Fruit consumed was consistently small-to moderate-sized (mean: 1 cm diameter), but fruit of different species of plants showed high morphological diversity. I classify the fruit of 31 plant species into three morphological groups: capsule, fig, and drupe/berry. Each of the primarily frugivorous birds of paradise was recorded taking fruits from 10-21 plant species, including representatives from each class.
The monogamous Trumpet Manucode and Crinkle-collared Manucode were fig specialists. More than 80% of their diet was figs. The polygamous species of paradisaeids were more "generalized" fruit-feeders and took significant amounts of fruit from all three morphological categories. The most important types of fruit among the polygamous birds were capsular species (49% of diet). While fig species were visited by birds from many families, most nonfig trees hosted a narrower range of foragers, and two species of trees, Chisocheton weinlandii (Meliaceae) and Gastonia spectabilis (Araliaceae), were visited only by birds of paradise.
The frugivorous habits of birds of paradise are similar in several respects to those of the neotropical cotingids and manakins. It is argued that while frugivory is an important component of the evolution of polygamous arena display in these birds, it cannot, by itself, explain why some birds are polygamous and others monogamous. Frugivory in the tropics is a complex syndrome that offers a number of ecological alternatives that, in turn, promote different behavioral adaptations.
Notes on the Behavior of the Costa Rican Sharpbill (Oxyruncus cristatus frater)
Authors: Stiles F. Gary , Whitney Bret 
Published: October 2019

Abstract
The Costa Rican Sharpbill (Oxyruncus cristatus frater) is a chunky bird of stolid demeanor, with rapid and jerky movements. Males apparently form exploded leks of 3-4 birds, advertising their lek territories by singing a high, thin, wiry, descending trill from conspicuous perches high in the canopy of precipitous, mid-elevation rain forest. The singing (and probable breeding) season extends from late February or March to late May or early June. The bright vermilion crest of the males is erected during intense aggressive interactions but not during singing. Probable courtship is described, but we were unable to observe copulation. We also describe a probable flight display of unknown significance. Sharpbills employ varied foraging tactics and take both fruit and animal prey. The sharp-pointed bill is used to pry open rolled leaves, undehisced fruits, and tufts of moss and epiphytes. The Sharpbills' bill and foraging appear to represent a unique specialization within the great tyrannine suboscine radiation of the New World tropics and a striking convergence with the family Icteridae in particular.
Why Do Brown-Headed Cowbirds Perform the Head-Down Display?
Authors: Scott Thomas W. , Grumstrup-Scott Judith M. 
Published: October 2019

Abstract
Four hypotheses for the function of the head-down display performed by Brown-headed Cowbirds were tested with observational data from free-ranging and captive cowbirds. Free-ranging cowbirds performed 284 interspecific and four intraspecific displays during 59.2 daylight hours while roosting in mixed-species flocks adjacent to feeding areas. The most common recipients of displays, female Red-winged Blackbirds and House Sparrows, preened cowbirds during 25 displays. Cowbirds that had just been preened displayed more often than those that had not recently been preened. Captive cowbirds displayed intraspecifically 475 times during 13.3 h, and dominant captive birds displayed more often than their subordinates. The following hypothesis was proposed to explain the display's function: the head-down display of Brown-headed Cowbirds is an appeasing agonistic behavior, the displayor is most often dominant to the recipient, and subsequent displaying is stimulated by interspecific preening. The display may function in: (a) obtaining food, (b) minimizing roosting energetics, and/or (c) establishing flock order.
Clutch Size in the Eastern Kingbird: Factors Affecting Nestling Survival
Authors: Murphy Michael T. 
Published: October 2019

Abstract
Observational and experimental procedures were used to evaluate the potential importance of brood size and weather on the evolution of clutch size in the Eastern Kingbird. Modal clutch size was three eggs, yet broods of four were most productive. Nestling size varied inversely with brood size, so that "nestling quality" was lower in broods of four than in broods of three. Asymptotic weight of nestlings in broods of three was directly and significantly correlated with ambient air temperature, followed by hatch order. Because larger broods were being fed during a period of relatively cool and wet weather, the effects of brood size were probably confounded by weather-induced changes in food availability, suggesting that the ability to produce surviving young successfully from large broods is dependent upon weather conditions during the nestling period. These observations match patterns seen in other aerial foragers and indicate that unpredictable changes in temperature and precipitation dramatically affect the ability of the adults to feed young. A high variance in fledging success from the largest broods is indicated and probably selects for a reduced number of offspring in the Eastern Kingbird. Trade-offs in reproductive effort and parental survival do not appear to be required to explain patterns of clutch size in the Eastern Kingbird or, probably, other aerial foragers.
Reproductively Dependent Song Cyclicity in Mated Male Mockingbirds (Mimus polyglottos)
Authors: Logan Cheryl A. 
Published: October 2019

Abstract
Mockingbird (Mimus polyglottos) song has been demonstrated to function in the species' perennial territoriality. Data reported here suggest that this species' diverse song may also function intersexually in reproduction. Observations on the amount of song produced by identified males throughout the breeding season revealed a pronounced cyclicity in the occurrence of song. Further, song cyclicity was systematically associated with the nature of the breeding activity in progress. In each of six mated males, the amount of song increased substantially while the male was nest building. The amount of song decreased significantly during incubation and during the care of offspring. This relationship held even when the cycle of breeding activities was disrupted through nest loss; males resumed singing immediately, although losses often occurred during periods of very little song. Analyses indicated that the nest-building song burst did not result from the activities involved in nest construction itself but often preceded the first observed instance of nest building. Increased song during nest building cannot be explained by excess amounts of unoccupied singing time available to males not engaged in the care of offspring. The overall pattern of results indicates that Mockingbird song may function in reproductive as well as in territorial contexts. Further, the cyclic relationship between song and breeding activities suggests that song may constitute a mechanism by which the reproductive state of the female is rapidly reset in preparation for subsequent broods.
Energetics and Growth Patterns of Three Tropical Bird Species
Authors: Bryant David M. , Hails Christopher J. 
Published: October 2019

Abstract
Energy budgets and growth data are presented for nestlings of three species of tropical insectivores: White-bellied Swiftlets (Collocalia esculenta), Blue-throated Bee-eaters (Merops viridis), and Pacific Swallows (Hirundo tahitica). A comparison with temperate nestlings, matched for body size, shows that the peak energy demand in our tropical sample averaged around 60% of temperate counterparts. We attribute savings to slow growth rates, reduced thermoregulatory requirements, a low resting metabolism (in swallows only), asynchronous hatching (in bee-eaters), and low nestling activity levels. Patterns of energy storage as lipid in nestlings of the three species were similar to the pattern in temperate swallows (Hirundinidae) and swifts (Apodidae), with those species feeding at the greatest heights, and hence on the most unpredictable supplies, storing the most fat while in the nest.
Obligate and Facultative Brood Reduction in Eagles: An Examination of Factors that Influence Fratricide
Authors: Edwards Thomas C. , Collopy Michael W. 
Published: October 2019

Abstract
Fratricide in eagles (Accipitridae: Accipitrinae) is either obligate [second hatched nestling (C2) always dies] or facultative (C2 occasionally dies) and appears to be a function of relative size differences between siblings. Several factors, including time between hatching, differences in hatching weights, and possibly the sex of the nestling in conjunction with its hatching sequence, influence size difference. Size differences are modified further by feeding rates of young by adults. These factors determine the relative differences in locomotor development and coordination and thus the ability of the first-hatched nestling to control access to and monopolize parent-provided resources. Significantly greater (P < 0.0001) within-clutch volume differences (an indicator of disparity in hatching weight) and greater time between hatching (mode of 3 versus 2 days) are found in eagles in which fratricide is obligate (three species) than in those in which fratricide is facultative (eight species). We suggest that these differences are proximate mechanisms that account for observed differences in the frequency of fratricide in eagles. Although size difference is determined in part by the sex and hatching sequence of the nestling, the role of offspring sex in fractricide is not clear.
Behavior and Taxonomic Status of Grayson's Dove
Authors: Baptista Luis F. , Boarman William I. , Kandianidis Paraskevas 
Published: October 2019

Abstract
Grayson's Dove (Zenaida graysoni) is extinct in the wild but is still found in aviaries. It has been treated variously as a full species or as a subspecies of the Mourning Dove (Z. macroura). The two taxa differ in shape, color, and color pattern of the rectrices and can be readily distinguished by characteristics of museum skins. They also differ in vocalizations and visual displays. Previous studies described differences in serology. The two taxa interbreed only rarely in captivity. It is proposed that Z. graysoni be recognized as a full species, closely related to Z. macroura.
The Influence of Nectar Resources on Nesting Success and Movement Patterns of the Common Amakihi (Hemignathus virens)
Authors: Riper Charles van 
Published: October 2019

Abstract
The objectives of this study were to investigate the influence of nectar resources on: (1) territory establishment, (2) breeding success, and (3) postbreeding dispersal in Hemignathus virens on Mauna Kea, Hawaii. I observed color-banded individuals from 1971 to 1981 and manipulated food during the 1975 breeding season by placing supplementary nectar resources in an area where breeding had not occurred in the previous 4 yr.
The results of this study demonstrated that H. virens is intrinsically tied to the nectar resources available within its breeding territory and that a minimum of 2,000 μl/day (1,400 cal) of nectar must be present before territory establishment will occur. This finding was further supported by the fact that no breeding occurred in the experimental area during the 6 yr after removal of the supplementary nectar.
Breeding success of Hemignathus virens was influenced by different levels of nectar availability. The most successful breeding occurred at nectar levels of 20,000-40,000 μl/day (14,000-28,000 cal). More than 35,000 μl/day (24,500 cal) of nectar within a territory generally inhibited successful breeding, presumably because too much time was spent in the defense of the nectar sources. Birds with larger amounts of nectar within their territories had concomitantly larger clutch sizes. Postbreeding dispersal, an annual phenomenon in the H. virens population on Mauna Kea, did not occur if adequate food supplies remained available during the nonbreeding period.
Dietary Selectivity in Relation to Availability and Quality of Food for Goslings of Cackling Geese
Authors: Sedinger James S. , Raveling Dennis G. 
Published: October 2019

Abstract
Food selection by and diet of Cackling Goose (Branta canadensis minima) goslings were studied in relation to the quality and availability of food during brood rearing, 1977-1979. Arrowgrass (Triglochin palustris) was the most important food in the diet of goslings before wing-molt of adults and sometimes during molt. Carex mackenziei was the most common sedge in the diet but was less important than arrowgrass. Leaves of other species were relatively unimportant during premolt. Arrowgrass declined, while Carex seeds and crowberries (Empetrum nigrum) increased, in the diet as brood rearing progressed. Arrowgrass was highly preferred, whereas other sedges and grasses (except C. mackenziei) were avoided in areas for which both availability and consumption were measured. Preference for arrowgrass was related to its higher protein and energy content and lower cell-wall content compared to other forage species. Thus, geese benefitted nutritionally from selecting their preferred diet. Seeds and berries contained high levels of lipids and carbohydrates relative to green leaves. Less arrowgrass was consumed in a year when brood densities were higher than in the other 2 years of the study. Arrowgrass availability declined as brood rearing progressed in another year. Thus, Cackling Geese may have been reducing the availability of their most nutritious food, at least at high brood densities. Food quality in breeding areas may be influencing population dynamics of geese despite the high overall availability of green plants.
Dominance Structuring of a Red-Winged Blackbird Roost
Authors: Weatherhead Patrick J. , Hoysak Drew J. 
Published: October 2019

Abstract
Observations of the behavior of roosting male Red-winged Blackbirds (Agelaius phoeniceus) indicated that after hatching year (AHY) males were dominant over hatching year (HY) males. This dominance resulted in AHY males occupying central roost positions in dense vegetation and HY males occupying edge positions in sparse vegetation. Overall, the birds preferred positions over deep water, although the edge positions of HY males were over deeper water than were the positions of AHY males. These results are consistent with the two-strategies roosting hypothesis (Weatherhead 1983), in that the dominance of older males allows them access to roost positions with relatively low vulnerability to predation. In this study, these positions also appeared to be microclimatically superior. These results also suggest that the bright plumage of adult males of sexually dimorphic species may be advantageous in some nonbreeding situations in addition to their more commonly recognized role in reproduction.
Variation in Peregrine Falcon Eggs
Authors: Burnham William A. , Enderson James H. , Boardman Thomas J. 
Published: October 2019

Abstract
Eggs collected from captive and wild Peregrine Falcons (Falco peregrinus) were used to examine variation in eggshell thickness, length, breadth, and initial weight to resolve questions about eggshell data from wild falcons. For captive falcons, shell thickness of first clutches did not change over the years a falcon laid or with embryonic development. Eggshells in third clutches, but not second clutches, were significantly thinner than those from first clutches. Greatest variation in shell thickness existed between eggs within a clutch and did not differ significantly between wild and captive eggs. Entire clutches of wild falcons should be represented in future studies to maximize the chance of obtaining a representative sample in regard to shell thickness. Egg size (L, B, and fresh weight) decreased over the years a captive falcon laid. A significant decrease in size (B and fresh weight) also occurred in second and third clutches laid the same year. Ratcliffe's Index generally appeared to be a reliable indicator of shell thickness in captive-laid eggs.
Thermal Consequences of Roost-site Selection: The Relative Importance of Three Modes of Heat Conservation
Authors: Walsberg Glenn E. 
Published: October 2019

Abstract
Thermal factors potentially important in the selection of nocturnal roosts by birds include shelter from wind, local increases in air temperature, and improvement in radiation balance. I analyze the relative importance of these three factors using data describing the thermal relations of Phainopepla nitens and the meteorological properties of winter roost sites selected by this species. Shelter from forced convection provides approximately 5 times more thermal benefit than improvement of radiation balance. Possible metabolic heating by the bird of air within the roost site is unimportant.
Dispersal in White-Crowned Sparrows: A Computer Simulation of the Effect of Study-Area Size on Estimates of Local Recruitment
Authors: Cunningham Michael A. 
Published: October 2019

Abstract
Consideration of the problem of sampling a population within a finite study area suggested that recruitment results might be related to the size of the study area. Specifically, the proportion of recruits observed within a defined study area that originate in that area (local recruits) should be a function of the proportion of the population that the study area represents. Computer simulations of dispersal, using Nuttall's White-crowned Sparrow (Zonotrichia leucophrys nuttalli) as a model, were designed to test this hypothesis, and the effect of territory size and population size on this relationship. The simulations confirmed that local recruitment is a function of the proportion of the population sampled in the study area. Additionally, these simulations demonstrated that by holding the distribution of dispersal distances constant, local recruitment for a given proportion of the population sampled increased with territory size and population size. These latter results, however, are artifacts of the simulations and have no biological significance. Finally, the proportion of local recruits predicted for a natural population was remarkably close to that obtained from fieldwork. I suggest that conclusions about dispersal and population structure should not be drawn from proportions of local recruitment within finite study areas, and require more detailed analysis of dispersal.
Vigilance Patterns of Bald Eagles Feeding in Groups
Authors: Knight Susan K. , Knight Richard L. 
Published: October 2019

Abstract
Patterns of vigilant behavior of wintering Bald Eagles (Haliaeetus leucocephalus) feeding on spawned salmon were examined in 1983-1984 on the Nooksack River in northwestern Washington. Vigilance in feeding birds has, in general, been attributed to predator detection; however, we proposed an additional function of vigilance in socially feeding birds that are vulnerable to food robbery and possible injury by conspecifics. We tested predictions of two nonexclusive hypotheses: (1) eagles look up while feeding to detect danger from humans, and (2) eagles look up while feeding to detect pirating attempts or avoid injury by conspecifics.
Results suggest that the function of vigilance varies, depending on the size of the feeding group. Vigilance patterns of eagles feeding in small groups (1-4 eagles) and medium groups (5-7 eagles0 are consistent with hypothesis 1, whereas those of eagles feeding in large groups (8-14 eagles) are consistent with hypothesis 2. Eagles in small groups were more vigilant (measured as scanning time and rate of head raising) when feeding near potential danger (riverbank cover) than when far from danger. Adult eagles feeding in areas of intense human activity were more vigilant than immatures feeding at the same site and were more vigilant than both adults and immatures feeding at secluded sites. Vigilance declined as group size increased from 1 to 4 eagles, and increased as group size ranged from 8 to 14 eagles. Feeding eagles that were looking up at the time of a pirating attempt were more successful in keeping their food than eagles with their heads down. In feeding areas where human activity was minimal, eagles formed larger groups than at more disturbed sites.
A Previously Unknown Plumage of First-Year Indigo Buntings and Theories of Delayed Plumage Maturation
Authors: Rohwer Sievert 
Published: October 2019

Abstract
First-year, but not adult, Indigo Buntings (Passerina cyanea) have a previously unknown supplemental plumage. The presupplemental molt includes all of the rectrices, the outermost but not the innermost primaries, and, typically, the three innermost secondaries and all body feathers. In this molt, young females exchange one adult-femalelike plumage for another, while young males exchange an adult-femalelike plumage for one that matches that of adult males in winter. Thus, in their first year Indigo Buntings wear: first, the juvenile plumage, the body feathers of which begin replacement before the tail is fully grown; second, the first basic plumage, which in both sexes is entirely femalelike in coloration and includes the juvenile remiges and rectrices; third, the supplemental plumage, assumed either prior to fall migration (<10% of individuals) or on the wintering ground (>90% of individuals) and in which obvious sexual dichromatism is first achieved; and fourth, the first alternate plumage, acquired in a prolonged and often incomplete prealternate molt of body feathers that occurs during February, March, and April on the wintering ground and during the spring in the United States. Because almost all of the femalelike first basic plumage of young males is lost in the presupplemental molt, this plumage almost certainly is an adaptation to conditions encountered either in the fall or early in the first winter. Furthermore, the ensuing supplemental plumage cannot be compromised by color requirements of the first breeding season because of the intervening prealternate molt; thus, the adult-malelike plumage produced by the presupplemental molt likely evolved to meet a change in signaling requirements that occurs in early winter. The signaling function of this plumage is unknown. Because this supplemental plumage of young males resembles the winter plumage of adult males and because all feathers grown by young males in their first prealternate molt resemble those of the adult male breeding plumage, the female mimicry hypothesis of Rohwer et al. (1980) is untenable for the subadult breeding plumage of yearling male Indigo Buntings.