bluuebunny/crossref_metadata_2025_split huggingface dataset:
Taxonomic Affinities of Audubon's Shearwater from Europa Island
Authors: Le Corre Matthieu 
Published: September 2019

Abstract
The western Indian Ocean holds five subspecies of the pantropical Audubon's Shearwater (Puffinus lherminieri), but none was known to breed in the Mozambique Channel. Here, I describe a newly discovered population of Audubon's Shearwaters on Europa Island, southern Mozambique Channel. Comparison of geographic variation of morphometric characters showed that the birds of this population belong to the P. l. bailloni subspecies, previously thought to be endemic to the Mascarenes Islands. They were distinct from the three subspecies of the Comoro, Aldabra, and Seychelles group, suggesting that few successful exchanges of individuals occur between north of the Mozambique Channel and Europa Island. This biogeographic pattern is similar to that of two phylogenetically independent pelagic species from Europa Island. This suggests that a common cause related to geographic isolation and oceanic conditions in the Mozambique Channel may explain the apparent isolation of these three seabird populations from Europa Island.
Difficulties Storing and Preserving Tyrant Flycatcher Blood Samples used for Genetic Analyses
Authors: Conrad Kelvin F. , Robertson R. J. , Boag P. T. 
Published: September 2019

Abstract
We stored blood samples of Eastern Phoebes (Sayornis phoebe) in a lysis buffer (“QLB”) that has been used successfully to preserve blood samples of many other species. We found that although samples from adults were not affected greatly, samples of nestling blood stored for more than a few days did not reliably produce the quantity and quality of DNA useful for multi-locus DNA fingerprinting. We also were unable to extract usable DNA from blood samples collected from Eastern Kingbird (Tyrannus tyrannus) nestlings, but obtained usable DNA from blood of Least Flycatcher (Empidonax minimus) nestlings stored for more than a year. We recommend that anyone planning DNA research with tyrant flycatchers should conduct their DNA extractions as soon as possible after collection. A pilot study to test methods of storage, preservation, and extraction may be necessary before beginning a large-scale project.
Winter Androgen Levels and Wattle Size in Male Common Pheasants
Authors: Papeschi Anna , Briganti Federica , DessÌ-Fulgheri Francesco 
Published: September 2019

AbstractWe report the results of morphological and hormonal measurements of 101 male Common Pheasants (Phasianus colchicus) captured during winter and at the beginning of the breeding season in order to identify correlates of ornament size. Androgen levels in January were bimodally distributed with one group with low hormone levels and a second group with high levels. In February, log transformed androgen levels were normally distributed, with all males showing values similar to the high-level group in January. Wattle size was positively correlated with androgens in January but not in February, suggesting that this male trait can indicate the ability of quality males to start earlier androgen production.
Following of Brown Capuchin Monkeys by White Hawks in French Guiana
Authors: Zhang Shuyi , Wang Lixin 
Published: September 2019

AbstractOne group of brown capuchin monkeys (Cebus apella) was observed for 19 months in French Guiana. White Hawks (Leucopternis albicollis) were seen in association with these monkeys throughout the year. Our study revealed that: (1) hawks mainly followed capuchins in open forest types, and in this vegetation they mainly flew at the height of 10–20 m from the ground where horizontal visibility is better than in other strata of the forest, (2) hawks usually landed preceding the monkey troop spreading into an area, and they followed the capuchin troop when the monkeys were traveling, and (3) no predation of any capuchins by hawks occurred at any time during our study, and seven times it was observed that hawks captured arboreal snakes disturbed by the movement of capuchins. We propose that White Hawks followed brown capuchins in this Amazonian forest primarily for capturing arboreal snakes disturbed by monkey troop movements.
Breeding Biology of Gray-Crowned Tyrannulet in the Monte Desert, Argentina
Authors: Mezquida Eduardo T. , Marone Luis 
Published: September 2019

AbstractWe present information from 75 nests of Gray-crowned Tyrannulet (Serpophaga griseiceps) found in open Prosopis woodlands of the central Monte desert between 1995 and 1997 and compare it with information corresponding to other species of the genus. Breeding occurred from October to January. Nests are small open cups. Both parents participated in nest building, which lasted 4–7 days. In the Prosopis woodland, 98% of the nests were built in chañar (Geoffroea decorticans), which also is commonly used as a nest plant by S. subcristata in east-central Argentina. Mean clutch size did not vary among years nor within the breeding season, and it was similar to that observed in other Serpophaga. Both male and female shared the 13–15 day incubation period. Hatching was asynchronous. Nestling period lasted 13–14 days, during which both parents reared the chicks. Nesting success (26%) appeared to be less than that previously reported for Nearctic open-nesters (50–60%), and Neotropical open-nesters in dry (50%) and wet tropics (35%). Egg and nestling predation were the main cause of nest failure.
Rufous Hummingbird Sucrose Preference: Precision of Selection Varies with Concentration
Authors: Blem Charles R. , Blem Leann B. , Felix Joel , van Gelder Jennifer 
Published: September 2019

Abstract
We tested concentration preferences of Rufous Hummingbirds (Selasphorus rufus) offered sucrose solutions in small feeders in the field. When sucrose solutions differing in increments of 10%, from 10% to 70%, were presented simultaneously, hummingbirds preferred 50% to higher and lower concentrations. They did not show a significant preference in the range from 50% to 70% . When options were offered in pairs of choices differing from 1–25%, hummingbirds demonstrated statistically significant preferences that varied with mean concentration in a curvilinear manner. At concentrations approximating those of hummingbird-pollinated flowers (20%), hummingbirds showed greatest specificity and could distinguish solutions differing by only 1%. At concentrations above and below 20%, greater differences between choices were required to elicit significant preferences.
Endocrine Control of Life-Cycle Stages: A Constraint on Response to the Environment?
Authors: Jacobs Jerry D. , Wingfield John C. 
Published: September 2019

AbstractMost organisms live in seasonal environments that fluctuate on a predictable schedule and sometimes unpredictably. Individuals must, therefore, adjust so as to maximize their survival and reproductive success over a wide range of environmental conditions. In birds, as in other vertebrates, endocrine secretions regulate morphological, physiological, and behavioral changes in anticipation of future events. The individual thus prepares for predictable fluctuations in its environment by changing life-cycle stages. We have applied finite-state machine theory to define and compare different life-history cycles. The ability of birds to respond to predictable and unpredictable regimes of environmental variation may be constrained by the adaptability of their endocrine control systems. We have applied several theoretical approaches to natural history data of birds to compare the complexity of life cycles, the degree of plasticity of timing of stages within the cycle, and to determine whether endocrine control mechanisms influence the way birds respond to their environments. The interactions of environmental cues on the timing of life-history stages are not uniform in all populations. Taking the reproductive life-history stage as an example, arctic birds that have short breeding seasons in severe environments appear to use one reliable environmental cue to time reproduction and they ignore other factors. Birds having longer breeding seasons exhibit greater plasticity of onset and termination and appear to integrate several environmental cues. Theoretical approaches may allow us to predict how individuals respond to their environment at the proximate level and, conversely, predict how constraints imposed by endocrine control systems may limit the complexity of life cycles.
Vocal Signals of the Village Weaver: A Spectrographic Key and the Communication Code
Authors: Collias Nicholas E. 
Published: September 2019

AbstractVocal signals of a species are social signals and guides to its social life. Sound spectrograms were made of 21 of the 26 vocal signals in the extensive vocal repertoire of the African Village Weaver (Ploceus cucullatus). A spectrographic key to vocal signals helps make these signals comparable for different investigators. Short-distance contact calls are given in favorable situations and are generally characterized by low amplitude and great brevity of notes. Alarm cries are longer, louder, and often strident calls with much energy at high frequencies, whereas threat notes, also relatively long and harsh, emphasize lower frequencies. Each male displays his newest nest in a colony with an individually distinctive call to unmated females. The most harmonic calls of the species include a loud call by a male when an unmated female first enters his nest, and also very soft, brief notes given by parent birds to attract a fledgling. Males use somewhat different songs to defend territory, for courtship, and for advertisement. Application of Darwin's (1872) principle of antithesis suggests that vocal signals are composed of basic elements that vary in duration, frequency, loudness, and tonality of notes. These variations can be arranged in pairs of opposite extremes serving to reduce ambiguity in signals, in effect a communication code. At the same time, other selection pressures can enter in according to circumstances to modify the expression of this basic code in evolution.
Local and Regional Effects of Pedestrians on Forest Birds in a Fragmented Landscape
Authors: Fernández-Juricic Esteban 
Published: September 2019

Abstract
I assessed the effects of pedestrians on the distribution of forest bird species in wooded parks in the city of Madrid within and between fragments. Within fragments, increasing levels of pedestrians reduced species richness and overall abundance of individuals within circular plots. The abundance of foraging individuals of four species (Magpies Pica pica, Blackbirds Turdus merula, Starlings Sturnus unicolor, and Woodpigeon Columba palumbus) diminished when pedestrians walked near sampling plots, as well as their breeding densities in relation to increasing disturbance levels. Between fragments, after controlling for fragment size effects, pedestrian rate was negatively related to species richness in two breeding seasons. Species turnover was positively associated to mean pedestrian rate and inter-annual variability in pedestrian rate. At the species level, pedestrian rate negatively affected the probabilities of fragment occupation of 16 species beyond the effects of fragment size and isolation. Locally, the short-term behavioral responses to visitors may reduce the suitability of highly disturbed parks in such a way as to decrease breeding densities and the probabilities of fragment occupation and persistence. The effects of human disturbance in fragmented landscapes should be incorporated into management decisions as another relevant factor that may reduce habitat quality.
Influence of Treefall Gaps on Distributions of Breeding Birds Within Interior Old-Growth Stands in Białowieża Forest, Poland
Authors: Fuller Robert J. 
Published: September 2019

AbstractBreeding birds were counted using point counts at 50 treefall gaps and 50 closed-canopy sites within one of the largest tracts of old-growth forest in Europe. Numbers of species and individuals were slightly, but significantly, higher at gaps. Overall bird species composition differed substantially at gaps and non-gaps. Dunnock (Prunella modularis), Blackcap (Sylvia atricapilla), and Chiffchaff (Phylloscopus collybita) were significantly more abundant at gaps. Wood Warbler (Phylloscopus sibilatrix) and Red-breasted Flycatcher (Ficedula parva) were significantly more abundant at non-gaps. Warblers (Sylviidae), ground insectivores, ground nesters, and short-distance migrants were significantly more abundant at gaps, but no species groups were more abundant at non-gaps. Eight species breeding in forest edges and young plantations in eastern Poland were not recorded in natural treefall gaps. The proportion of tropical migrant passerines was considerably higher in closed-canopy stands (0.47) than at gaps (0.29), which contrasts with the situation in most managed European forests where the highest proportions of tropical migrants typically occur in young-growth forests.
Sleep-Vigilance Trade-Off in Gadwall During the Winter Period
Authors: Gauthier-Clerc Michel , Tamisier Alain , Cézilly Frank 
Published: September 2019

AbstractWe studied vigilance while sleeping in wintering Gadwalls (Anas strepera) in the Camargue (southern France) during the 1992–1993 and 1994–1995 winters. Vigilance while sleeping was reduced at the beginning and at the end of the winter. During mid-winter, birds in sleeping posture showed the highest level of vigilance, with longer peeks and shorter interpeek intervals. There was no effect of sex on the intensity of vigilant sleep, nor on changes in the pattern of vigilant sleep across the winter period. We discuss the results in relation to the behavioral ecology and energetic constraints of wintering Gadwalls in the Camargue. We suggest that the variation in sleep, measured by eye-closure, and vigilance, measured by eye-opening, in relation to winter period is a result of a trade-off between two opposite requirements: to save energy by sleeping and to monitor the environment by being vigilant.
Correlates of Reproductive Success in Cooperatively Breeding Western American Crows: If Helpers Help, It's Not by Much
Authors: Caffrey Carolee 
Published: September 2019

Abstract
I measured annual reproductive success for a resident population of cooperatively breeding Western American Crows (Corvus brachyrhynchos hesperis) over 6 years, and examined the relationship between it and several ecological and social variables. Most nests (57%) failed to fledge any young, due largely to predation. Success in fledging young was associated with three interrelated variables: (1) the presence of helpers, (2) early nesting, and (3) consistent differences between pairs. Assisted pairs began incubation earlier, some pairs consistently nested early, and the proportion of years that pairs were successful was related to the proportion of years in which they had help. Although both help and incubation date were related to nesting success independent of each other, the effect of help became nonsignificant after controlling for differences between pairs. The slight increase in fledging success possibly attributable to helpers may have been the result of consistently successful pairs succeeding, with help, in otherwise poor years. Postfledging survival was related in part to the size of individuals; larger nestlings tended to have a greater chance of fledging, and once fledged, to have a greater chance of surviving the following 2-week period. Larger nestlings survived to one year of age significantly more often than smaller nestlings.
Badge Size and Extra-Pair Fertilizations in the House Sparrow
Authors: Whitekiller R. R. , Westneat David F. , Schwagmeyer P. L. , Mock Douglas W. 
Published: September 2019

AbstractFor House Sparrows, Passer domesticus, it has been proposed that the size of a male's throat badge correlates with his success in avoiding cuckoldry as well as obtaining extra-pair copulations (EPCs), and that females gain indirect (genetic) benefits from EPCs with large-badged males. Alternatively, female House Sparrows may engage in EPCs as a guard against their social mate's infertility. We used multi-locus DNA fingerprinting to examine paternity and found that among 41 broods and 136 offspring, 20% of the offspring were attributable to extra-pair fertilizations (EPFs). Forty-one percent of the 34 males were cuckolded; however, large-badged males were as likely to be cuckolded as small-badged males. Moreover, we found no evidence that large-badged males were inherently superior to small-badged males in terms of survivorship. We compared the prevalence of unhatched eggs in broods with and without extra-pair offspring to determine whether EPFs are associated with hatching failure. Although we detected no association between hatch failure and EPFs, enhanced fertility remains a plausible EPC benefit to females, but experimental approaches may be required to evaluate its significance.
Copulation Behavior in the Osprey in Relation to Breeding Density
Authors: WidÉn Per , Richardson Malena 
Published: September 2019

AbstractWe studied Osprey (Pandion haliaetus) copulation behavior in two geographically separated subpopulations with different breeding densities. In the low density area, the nearest neighbor distance between nests was 7 km, and in the high density area 1.4 km. The frequency of successful copulations was significantly higher in the high density area, 0.65 hr−1 as compared to 0.30 hr−1. Extra-pair copulations were recorded only in the high density area, and extra-pair visits by intruding Ospreys also were more frequent there. There was no relation between copulations and delivery of food or nest material. Our results support the idea that copulation behavior is related to breeding density, but whether or not this is a result of sperm competition or some other social factor remains undetermined.
Survival and Song-Type Sharing in a Sedentary Subspecies of the Song Sparrow
Authors: Wilson Pamela L. , Towner Mary C. , Vehrencamp Sandra L. 
Published: September 2019

AbstractThe extent and spatial pattern of song-type sharing among neighboring males in one subspecies of Song Sparrow, Melospiza melodia cooperi, were examined in two San Diego County populations. Repertoire size averaged 9.6 song types per male (range 7 to 14). Song-type sharing was greatest between neighbors and declined with distance between territories. Adjacent neighbors shared an average of 22% of their song types. Variation in the amount of sharing between adjacent territory owners was high, ranging from 0% to 86% repertoire overlap. Results are consistent with the expected pattern produced by age-restricted learners that attempt to establish territories near tutors. The probability of a male surviving and remaining on his territory through the breeding and nonbreeding season increased as the fraction of song types shared with adjacent neighbors increased. The amount of song-type sharing may therefore be an indicator of a male's competitive ability to obtain a preferred territory near his tutors, or it may determine a male's effectiveness in using shared and unshared song types to communicate aggressive intentions.
Nest Site Selection and Productivity of Suburban Red-Shouldered Hawks in Southern Ohio
Authors: Dykstra Cheryl R. , Hays Jeffrey L. , Daniel F. Bernard , Simon Melinda M. 
Published: September 2019

AbstractWe measured nest site selection and productivity of suburban-nesting Red-shouldered Hawks (Buteo lineatus) in southwestern Ohio and rural-nesting Red-shouldered Hawks in south-central Ohio. At both the suburban and the rural locations, nest sites had greater canopy height and overall tree basal area than paired random plots, and were located closer to water than were paired random plots. Nest trees also had greater diameter and height than random plot-center trees. Reproductive rates at suburban and rural sites were similar, averaging 2.6–3.1 nestlings per successful nest. Results indicated that suburban-nesting Red-shouldered Hawks were very similar to rural-nesting hawks in both nest site selection and productivity, suggesting that Red-shouldered Hawks were habituated to their suburban environs.
The Rufous Cacholote (Furnariidae: Pseudoseisura) is Two Species
Authors: Zimmer Kevin J. , Whittaker Andrew 
Published: September 2019

AbstractNew information on the vocalizations and behavior of populations of the Rufous Cacholote (Pseudoseisura cristata), combined with a morphometric analysis of museum specimens, reveal that it actually consists of two biological species: a form that is restricted to the arid caatinga region of northeastern Brazil (P. cristata), and a wider-ranging form (P. unirufa) that occupies seasonally flooded savannas and deciduous woodlands in northern and eastern Bolivia, northern Paraguay, and southwestern Brazil. Long considered a subspecies of P. cristata, P. unirufa is shown to be morphologically, vocally, and ecologically distinct from allopatrically distributed populations of P. cristata. Reciprocal playback experiments of tape-recorded vocalizations indicate that neither form responds to the other's vocalizations. The two species may also differ in their breeding systems and social structures. P. cristata is shown to be a cooperative breeder, with nonbreeding helpers assisting in territorial defense, nest-building, and care of nestlings. No evidence of cooperative breeding was found in P. unirufa.
Responses of Egg-Laying Pied Flycatchers to Experimental Changes in Clutch Size: A Re-Examination
Authors: Kern M. D. , Cowie R. J. , Slater F. M. 
Published: September 2019

AbstractPrevious studies with small numbers of clutches suggested that Pied Flycatchers (Ficedula hypoleuca) were determinate egg-layers whose clutch size was fixed before laying began. We found that females lay additional eggs of normal size if clutch size is experimentally reduced, but do not lay fewer eggs when clutch size is increased. In the terms of Kennedy and Power (1990), Pied Flycatchers are removal-indeterminate and addition-determinate.
Egg Recognition in Yellow-Billed and Black-Billed Magpies in the Absence of Interspecific Parasitism: Implications for Parasite-Host Coevolution
Authors: Bolen Ginger M. , Rothstein Stephen I. , Trost Charles H. 
Published: September 2019

AbstractYellow-billed Magpies (Pica nuttalli) ejected 100% of nonmimetic eggs placed in their nests despite such behavior having no detectable present day benefits. They are not currently parasitized, nor is there any evidence of a recently extinct brood parasite. Furthermore, there was no molecular evidence of conspecific parasitism, and Yellow-billed Magpies accepted eight of nine conspecific eggs transferred between nests, so recognition would rarely be of benefit if conspecific parasitism occurred. Thus, we suggest that egg recognition in Yellow-billed Magpies is a plesiomorphic trait, a primitive character inherited from a remote ancestor, its nearest relative, the Black-billed Magpie (Pica pica). The latter suffers from parasitism by Great Spotted Cuckoos (Clamator glandarius) in Eurasia and displays rejection behavior throughout Europe in populations that are allopatric and sympatric with this cuckoo. As would be expected if Yellow-billed Magpies inherited rejection behavior from the Black-billed Magpie, or the common ancestor of both species, we found that North American Black-billed Magpies also have well developed egg recognition despite being unaffected by interspecific parasitism. The long-term retention of host defenses as is indicated by magpies has major implications for the coevolutionary interactions between brood parasites and their hosts.