bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Breeding and Postbreeding Movements and Habitat Requirements for the Scarlet Tanager (Piranga Olivacea) in Virginia
Authors: Vega Rivera J. H. , McShea W. J. , Rappole J. H. 
Published: September 2019

AbstractWe investigated movements and habitat use during breeding and postbreeding periods in Scarlet Tanagers (Piranga olivacea) during June-September 1998 in northern Virginia deciduous forest. Nine birds (8 males and 1 female) remained on the same home range during both breeding and postbreeding periods, whereas 11 birds (9 males and 2 females) shifted home range (>300 m) between periods. Breeding season home-range size ranged from 2.6 to 5.6 ha (95% kernel), and core area from 0.61 to 0.93 ha (50% kernel). Postbreeding home ranges were similar in size to home range during the breeding period for birds that remained in the vicinity of nesting areas, but were larger for birds that moved away from the nesting area. Scarlet Tanagers occurred in both mature and successional forest during breeding and postbreeding periods, with some indication of increased use of earlier successional stages during the postbreeding period. Needs for Scarlet Tanagers during the postbreeding period (molt, premigratory fattening) differ from those during the breeding period (pair formation, nest placement, rearing of young). Those differences provide a plausible explanation that all tanagers changed focal areas between breeding and postbreeding periods. These findings confirm the need for taking the postbreeding period into account, both for understanding migrant life history and successful conservation.
Seasonal and Diurnal Body-Mass Fluctuations for two Nonhoarding Species of Parus in Sweden Modeled Using Path Analysis
Authors: Rintamäkt Pekka T. , Stone Jon R. , Lundberg Arne 
Published: September 2019

Abstract
According to the hypothesis that has been invoked most frequently to explain seasonal fattening patterns for birds—the “adaptive winter-fattening hypothesis”—individuals respond to worsening foraging conditions by increasing body mass and energy reserves. Two hypotheses have been proposed equally frequently to explain daily weight gain patterns for birds: according to the “state-dependent foraging hypothesis,” energy reserves should be amassed early during the day, when starvation risk increases; according to the “mass-dependent predation-risk hypothesis,” mass gain should be delayed for as long as possible, to minimize predation risk. Those hypotheses have been tested previously, using statistical methods (e.g. multiple-regression analysis) that assume independence among environmental variables (e.g. photoperiod and temperature). We conducted path analyses that included four predictor variables (day-in-season, hour-in-day, mean daily temperature, and daily precipitation) to model body-mass fluctuations for two small, nonhoarding (noncaching) passerine species that inhabit central eastern Sweden. Data were partitioned hierarchically into species, age class, gender, and season subgroups. As reported in many small passerine species studies, body mass increased during the day and maximized at dusk; over seasons, body mass increased during autumn, maximized by midwinter, and declined toward breeding in spring. Path analysis models accounted for 9.5–49.9% (mean 26.3%) for Blue Tit (Parus caeruleus) body mass variance and 1.8–52.3% (mean 16.8%) for Great Tit (P. major) body mass variance; for both species, accountability was lowest for autumn (Blue Tit,12.2%; Great Tit, 7.3%), highest for winter (Blue Tit, 33.4%; Great Tit, 21.9%), and intermediate for spring (Blue Tit, 22.7%; Great Tit, 11.8%); for Blue Tits, it was greater for adults than for juveniles (33.2 and 21.7%); whereas negligible for Great Tits (15.9 and 17.3%) and slightly greater for males than for females (Blue Tit, 27.4 and 23.5%; Great Tit, 23.1 and 21.3%). Those results are consistent with predictions formulated on the basis of the adaptive winter-fattening, partially with state-dependent foraging, and, possibly, mass-dependent predation-risk hypothesies and reveal that body-mass fluctuations are associated to a greater extent with photoperiod than with temperature.
Beneficial Effects of Cloacal Bacteria on Growth and Fledging Size in Nestling Pied Flycatchers (Ficedula Hypoleuca) in Spain
Authors: Moreno Juan , Briones Víctor , Merino Santiago , Ballesteros Cristina , Sanz Juan J. , Tomás Gustavo 
Published: September 2019

AbstractEffects of bacteria on avian hosts in the wild have received little attention until recently. Whereas the pathogenic effects of bacteria are well known, positive effects of symbiotic bacteria are more rarely considered. Nestling growth has important repercussions for offspring fitness in avian populations and may be affected by microbial colonization of the gut. Enterococcus faecalis is a common opportunistic pathogen, whereas E. faecium has been used as a growth promoter because it interacts competitively with pathogenic bacteria, E. faecalis included. We followed the growth in tarsus length and mass of 18 Pied Flycatcher (Ficedula hypoleuca) broods. Chicks were weighed and measured on days 4, 8, 10, and 13 after hatching. On day 13, wing length was also measured and cloacal swabs were taken of two chicks in each brood for detection of enterococci. In all, the methods used allowed us to detect six species of bacteria among a possibly much richer community. Most chicks had E. faecalis, whereas E. faecium was less prevalent. There was a negative association between scores for E. faecalis and for the rest of the species pooled. The presence of E. faecalis showed no detectable association with nestling mass or size at any age, whereas the presence of the other species showed significantly positive associations with mass and size on day 13, but not before. Presence of E. faecium on its own was positively associated with nestling mass and size shortly before fledging. E. faecium may act as a growth promoter in the wild through its competitive interactions with facultative pathogenic bacteria. The presence of some microbes are critically important in avian growth and development.
Extrapair Paternity and Breeding Synchrony in Gadwalls (Anas Strepera) in North Dakota
Authors: Peters Jeffrey L. , Brewer Gwenda L. , Bowe L. Michelle 
Published: September 2019

AbstractExtrapair paternity and its correlates with breeding synchrony were examined in Gadwall (Anas strepera) using microsatellite DNA fingerprinting. Eleven of 261 ducklings (4.2%) within 8 of 29 broods (27.6%) had genotypes consistent with extrapair fertilizations, a comparable frequency to other species of waterfowl for which extrapair paternity has been documented. We found no evidence of intraspecific brood parasitism. The frequency of extrapair paternity was not significantly correlated with breeding synchrony. We suggest that female absences during egg-laying may have provided males with opportunities to pursue extrapair copulation when breeding was synchronous.
Function of Tail Streamers of Red-Tailed Tropicbirds (Phaethon Rubricauda) As Inferred From Patterns of Variation
Authors: Veit Allison C. , Jones Ian L. 
Published: September 2019

AbstractWe investigated the function of Red-tailed Tropicbird (Phaethon rubricauda) tail streamers by quantifying patterns of variation in streamers and other measurable traits on the basis of measurements of 659 individuals, including 422 of known age and 459 of known sex, measured in the field from 2000 to 2002. Our data were consistent with the idea that Red-tailed Tropicbirds' tail streamer ornaments function for mate attraction, but it suggested that variability in streamer expression is arbitrary and unlikely to provide a meaningful signal of individual quality during mate choice. The two elongated red tail streamers are composed of bilaterally symmetrical filamentous central rectrices with a black rachis and narrow red vane averaging 399 ± 1.8 mm (SE) in length when fully grown. Prior to breeding, individuals of opposite sex conspicuously display elongated red tail streamers during complex aerial courtship. Streamers exhibited measurement asymmetries (the difference between new and old fully grown tail streamers) of up to 144 mm because of wear at the tip of the older streamer, which accounts for most of the difference in the lengths of two fully grown streamers in individual birds. As in other putative sexually selected traits, tail streamers were more variable than nonornamental traits across individuals. Males were slightly larger than females in length of fully grown streamers (ratio 1.04), culmen length (ratio 1.02), and tarsal length (ratio 1.01). There was no correlation between fully grown streamer length and body size (score on first principal component) (r = 0.004), wing length (males, r = 0.05; females, r = 0.10), or mass (males, r = 0.10; females, r = 0.04), which is consistent with the hypothesis that streamers have an ornamental rather than aerodynamic function. There was a significant correlation between the ratio of streamer lengths (growing vs. fully grown, r = 0.50) of male and female pair members, indicating that at least the timing of ornament development was coordinated within pairs. However, tail streamers did not appear to be good indicators of an individual's “quality;” on the basis of 372 adults of known age (3–22 years), streamer length did not increase with age (r = 0.30) and was not correlated with an index of body condition (r = 0.03). The streamer length of pair members was not correlated with chick asymptotic body mass or chick fate, nor was female streamer length with egg size.
More Eggs the Better: Egg Formation in Captive Barn Owls (Tyto Alba)
Authors: Durant Joël M. , Massemin Sylvie , Handrich Yves 
Published: September 2019

Abstract
We studied rapid yolk deposition (RYD) in Barn Owls (Tyto alba) on the basis of the analysis of 26 eggs laid by “dye-dosed” captive female Barn Owls in five different broods. Pictures of yolks were examined to assess daily rates of yolk deposition. We used those data in combination with data from the dissection of ovaries of another five breeding females. We found that the total duration between initiation of RYD and laying of the corresponding egg was only 13.6 days, with an interval between yolk completion and oviposition of 2.4 days. The total number of follicles that may have given eggs was found to be 25. That high number of follicles and the short RYD period explain the particularly high reproductive potential of this nocturnal raptor species.
Blood Isotopic (δ13C and δ15N) Turnover and Diet-Tissue Fractionation Factors in Captive Dunlin (Calidris Alpina Pacifica)
Authors: Ogden Lesley J. Evans , Hobson Keith A. , Lank David B. 
Published: September 2019

AbstractAvian studies are often interpreted using dual (e.g. 13C, 15N) isotope models, assuming turnover of both isotopes occur at similar rates, but only a few studies have quantified turnover rates for more than one of those isotopes simultaneously. To test the generality of previous turnover and fractionation estimates and assumption of synchronous C and N patterns of turnover rates, we captured Dunlin (Calidris alpina pacifica) wintering in the Fraser River Delta, British Columbia, and derived isotopic turnover rates and diet-tissue fractionation factors by experimentally manipulating diet. Birds (n = 15) were initially fed a terrestrially derived diet (mean δ13C: −24.7‰, mean δ15N: 3.5‰) for 54 days. A treatment group (n = 11) was then switched to a marine-derived diet (mean δ13C: −18.3‰, mean δ15N: 13.7‰); a control group (n = 4) was maintained on the terrestrial diet for a further 59 days. An exponential model described patterns of isotopic turnover for 13C and 15N, and turnover rates and half-lives of the two isotopes were correlated, confirming the assumption of synchronous patterns of turnover for those isotopes. The half-lives for 13C and 15N in Dunlin whole blood were 11.2 ± 0.8 days and 10.0 ± 0.6 days, respectively, and are among the lowest values obtained to date for wild birds. Variation in turnover rate among individuals was not related to indices of body condition.
Night Movements of Young Reed Warblers (Acrocephalus Scirpaceus) in Summer: Is it Postfledging Dispersal?
Authors: Mukhin Andrey 
Published: September 2019

AbstractI studied summer movements of juvenile Reed Warblers (Acrocephalus scirpaceus) marked as nestlings during four field seasons (1999–2002). To control for birds' movements, nocturnal playback of songs and daytime mist-netting were done. Captures by song playback suggest the existence of nocturnal postfledging movements in Reed Warblers. Birds' age (days) during such movements was found to be 39–52 days. I analyze the temporal schedule and physiological condition of the birds during this period and discuss the mechanism of nocturnal postfledging dispersal and its background and relationships with other events of the annual cycle during the premigratory period.
Habitat Requirements and Selection by Kelp Gulls (Larus Dominicanus) in Central and Northern Patagonia, Argentina
Authors: Borboroglu Pablo García , Yorio Pablo 
Published: September 2019

Abstract
We analyzed habitat requirements and selection of Kelp Gulls (Larus dominicanus) breeding at 68 colonies along 2,500 km of coastline in Patagonia, Argentina. Kelp Gulls use a wide range of nesting habitats that include areas with shrub, grass, and herbs which provide different degrees of cover; open ground of various substrate types; and slopes of widely different gradients, confirming the plasticity of the species with respect to habitat recorded elsewhere in the Southern Hemisphere. Eighty percent of the colonies were on islands, the probability of occupation of which increased with distance from mainland and availability of vegetation. Vegetation cover was a key component of nesting habitat for Kelp Gulls in Argentina. Gulls occupied areas with higher cover than random areas; but within vegetated areas, they showed preference for sparser cover that increased visibility and facilitated escape. Kelp Gulls often nested with other species of seabirds and seals and had a positive association with the Olrog's Gull (L. atlanticus).
A Red Bird in a Brown Bag: The Function and Evolution of Colorful Plumage in the House Finch.
Authors: Andersson Staffan 
Published: September 2019

Abstract
The following critiques express the opinions of the individual evaluators regarding the strengths, weaknesses, and value of the books they review. As such, the appraisals are subjective assessments and do not necessarily reflect the opinions of the editors or any official policy of the American Ornithologists' Union.
Structure and Organization of Canopy Bird Assemblages in Central Amazonia
Authors: Naka Luciano Nicolás 
Published: September 2019

AbstractI analyzed the species composition, structure, and trophic organization of bird assemblages in the forest canopy around Manaus, Brazil. Using three canopy towers located in primary terra firme forests, I conducted 117 censuses over a 13 month period, recording 160 bird species. The three study sites had similar species richness (between 126 and 128 species), sharing 95 species in common, which accounted for >90% of all individual records. Most species recorded in the canopy (110) belonged to the core canopy avifauna. The other 50 species included migrants (13), species that feed overhead (8), species from lower strata (15), night birds (3), and vagrants or visitors from open areas and second-growth forests (11). Most of those species, however, appeared in very low numbers in the forest canopy, except understory frugivores, which regularly fed on canopy fruits. Among the migratory species were some Nearctic (6), Austral (3), and species probably holding both migratory and resident populations in the area (4). Additionally, I found evidence that two species of parrots perform seasonal movements, leaving the forest canopy around Manaus during the dry season. Frugivores dominated the canopy avifauna in abundance, but contradicting results reported from other Neotropical forest canopies, insectivores and frugivores had equal species richness. The canopy avifauna was highly homogeneous among sites in terms of species richness, distribution among abundance classes, and number of species in each feeding guild, habitat, and microhabitat. As in Costa Rica, the canopy avifauna of Manaus was mostly composed by typical canopy bird species, and not by edge-living species as reported from Panama. I suggest that habitat fragmentation may affect the bird community composition in the forest canopy, allowing a higher influx of opportunistic species.
Natural Variation in Flight Performance is Related to Timing of Breeding in Tree Swallows (Tachycineta Bicolor) in New York
Authors: Bowlin Melissa S. , Winkler David W. 
Published: September 2019

AbstractIn many avian species, including Tree Swallows (Tachycineta bicolor), females that lay eggs earlier in the season have higher fitness. It has been hypothesized that nonheritable variation in individual quality could explain how variation in laying date persists in the face of this apparently directional selection. Previous experimental work on Tree Swallows has suggested that natural variation in flight ability enables early-laying females to attain feeding rates high enough to support egg production on earlier, sparser food than later-laying females. We tested that hypothesis with standardized flights through a 9.75-m flight-performance test tunnel. One group of female swallows was tested at the height of the breeding season on 28 May regardless of their nesting phenology; another group was tested on the 11th day of incubation. Average acceleration in the tunnel was negatively correlated with clutch initiation date for the females tested on 28 May. Daily variation in ambient environmental conditions had strong effects on swallow flight performance in the tunnel, and no relationship was observed in the day-11 birds. Because natural variation in foraging performance is correlated with variation in female Tree Swallows' clutch initiation dates, flight ability appears to be a key element of individual quality in this species.
Size Dimorphism, Intrasexual Competition, and Sexual Selection in Wattled Jacana (Jacana Jacana), A Sex-Role-Reversed Shorebird in Panama
Authors: Emlen Stephen T. , Wrege Peter H. 
Published: September 2019

AbstractWe studied sexual size dimorphism, intrasexual competition, and sexual selection in an individually marked population of Wattled Jacanas (Jacana jacana) in the Republic of Panama. Males are the sole incubators of eggs (28-day incubation) and primary providers of chick care (50–60 days). Females were 48% heavier than, and behaviorally dominant over, males. Females also showed greater development of secondary sexual characters (fleshy facial ornamentation and wing spurs) than males. Both sexes defended territories throughout the year against same-sex conspecifics. Competition for territorial space was intense, and many individuals of both sexes did not become breeders. Resident females further competed with one another to accumulate multiple mates, resulting in a mating system of simultaneous polyandry. Female and male residents (territory holders) were larger, heavier, and more ornamented than adult floaters of the same sex. Larger and heavier females also had more mates than smaller females. Body size was thus a critical predictor of success in intrasexual competition for territories (both sexes) and for mates (females). Three measures of sexual selection—(1) sex difference in the opportunity for sexual selection, (2) female-to-male ratio of potential reproductive rates, and (3) operational sex ratio—each indicated that sexual selection is currently operating more strongly on females than on males (female-to-male ratios ranged from 1.43:1 to 2.22:1). Values of 1.61:1 and 1.43:1 represent the first published quantitative estimates of the opportunity for sexual selection for any sex-role-reversed bird. Our study supports the theory that when increased parental care entails reduced opportunities for future reproduction, asymmetries in parental care behaviors of the sexes can influence the intensity of competition for mates and the direction and strength of sexual selection.
Survival, Habitat Use, and Movements of Fledgling White-Throated Robins (Turdus Assimilis) in a Costa Rican Agricultural Landscape
Authors: Cohen Emily B. , Lindell Catherine A. 
Published: September 2019

AbstractWe used radiotelemetry to study behavior of White-throated Robins (Turdus assimilis) during the postfledging dependent period. The study was conducted in a mixed agricultural and forested landscape in southern Costa Rica from March through August of 2001 and 2002. A transmitter was attached to one fledgling per brood (n = 53). Each bird was located daily prior to dispersal. We compared survivorship, habitat use, and movements of fledglings from (1) nests in coffee plantations and (2) nests in cattle pastures. The probability of surviving the first three weeks out of the nest was 0.67 ± 0.07 (SE) for fledglings from nests in all habitats, 0.58 ± 0.10 for fledglings from nests in coffee, and 0.74 ± 0.26 for fledglings from nests in pasture. Fledglings from nests in pasture left their nesting habitat at younger ages than did those from nests in coffee, and most birds from both habitats moved into forest when they left their nesting habitat. Pasture was rarely used during the postfledging period, whereas coffee plantations were used extensively. Fledglings that remained in agricultural habitats (coffee or pasture) were less likely to survive until dispersal than were those that moved into forested areas. Average daily distances from the nest gradually increased until fledglings dispersed away from the natal area, always into forest, and were not different for birds from pasture or coffee. White-throated Robins can nest successfully in agricultural habitats, but use of forest positively influenced survivorship of young during the postfledging dependent period.
Proximate Factors Determining Age and Mass at Fledging in Rhinoceros Auklets (Cerorhinca Monocerata): Intra- and Interyear Variations
Authors: Deguchi Tomohiro , Takahashi Akinori , Watanuki Yutaka 
Published: September 2019

AbstractIn alcids, growth rate and hatching date of chicks appear to affect fledging age and mass. Underlying mechanisms are hypothesized to be (1) critical wing length at fledging for postfledging survival, (2) synchronization of fledging to dilute predation risk, and (3) variable parental provisioning according to timing of breeding. To elucidate the effects of growth rate and hatching date on fledging age and mass, and to test those mechanistic hypotheses, we measured chick growth and fledging periods in Rhinoceros Auklets (Cerorhinca monocerata) at Teuri Island from 1995 to 2000. The multiple-linear regression analysis showed that intrayear variations of fledging age and mass were explained by growth rate or hatching date in five out of six years. Faster-growing chicks fledged younger and heavier, and earlier-hatched chicks fledged older and heavier. Consequently, no apparent correlation between fledging age and mass was observed in five out of six years. Analysis of interyear variation showed a negative correlation between fledging age and mass, which indicates that growth rates rather than hatching dates had a major effect. Wing length at fledging was independent of growth in mass. More than 80% of chicks fledged when they attained a narrow range of wing length (130–150 mm), presumably because they remained in their nests until they attained the critical wing length. In five out of six years, the chicks did not synchronize timing of fledging relative to timing of hatching. Later-hatched chicks attained lighter peak masses and at younger ages, which may indicate that their parents decreased provisioning rates when the chicks were still young. We suggest that (1) critical wing length at fledging and (2) variable parental provisioning according to timing of breeding could be underlying mechanisms determining these relationships between fledging age and mass.