bluuebunny/crossref_metadata_2025 huggingface dataset:
An Assessment of Song Admixture as an Indicator of Hybridization in Black-Capped Chickadees (Poecile Atricapillus) and Carolina Chickadees (P. Carolinensis)
Authors: Sattler Gene D. , Sawaya Patricia , Braun Michael J.
Published: September 2019

Vocal admixture often occurs where differentiated populations or species of birds meet. This may entail song sympatry, bilingually singing birds, and songs with intermediate or atypical characteristics. Different levels of vocal admixture at the range interface between Black-capped Chickadees (Poecile atricapillus) and Carolina Chickadees (P. carolinensis) have been interpreted as indicating that hybridization is frequent at some locations but not others. However, song ontogeny in these birds has a strong nongenetic component, so that inferences regarding hybridization based on vocal admixture require confirmation. We used diagnostic genetic markers and quantitative analyses of song to characterize population samples along two transects of the chickadee contact zone in the Appalachian Mountains. More than 50% of individuals at the range interface were of hybrid ancestry, yet only 20% were observed to be bilingual or to sing atypical songs. Principal component analysis revealed minimal song intermediacy. This result contrasts with an earlier analysis of the hybrid zone in Missouri that found considerable song intermediacy. Re-analysis of the Missouri data confirmed this difference. Correlation between an individual’s genetic composition and its song type was weak in Appalachian hybrid populations, and genetic introgression in both forms extended far beyond the limits of vocal admixture. Therefore, song is not a reliable indicator of levels of hybridization or genetic introgression at this contact zone. Varying ecological factors may play a role in producing variable levels of song admixture in different regions of the range interface.

Una Evaluación de la Mixtura de Cantos como Indicador de Hibridación en Poecile atricapillus y P. carolinensis
Stable-Isotope (C, N, H) Analyses Help Locate the Winter Range of the Coastal Plain Swamp Sparrow (Melospiza Georgiana Nigrescens)
Authors: Greenberg Russell , Marra Peter P. , Wooller Matthew J.
Published: September 2019

Some taxa of North American birds have unknown winter ranges, because of the difficulty in tracking individuals between seasons. Stable isotopes may provide clues to help locate these nonbreeding populations. Previously, no valid records existed for the Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens) from October to late April. We used stable-isotope (C, N, and H) analyses to provide estimates of where molt occurs and then searched those areas for individuals of this species. The δ13C and δ15N of rump feathers were consistent with the Coastal Plain Swamp Sparrow molting in more saline marshes than the nominate subspecies after the breeding season, which confirms what was already known. The values for the same isotopes from crown feathers revealed that winter molt in the Coastal Plain Swamp Sparrow probably occurred in similar coastal brackish habitats. The δD of crown feathers indicated that prebreeding molt occurred at latitudes between South Carolina and Virginia. A subsequent search of this region located 18 Coastal Plain Swamp Sparrows, all of which were found in North Carolina or southeastern Virginia. Coastal Plain Swamp Sparrows were found predominantly in brackish marshes similar to their breeding habitat. On the basis of these observations, it appears that Coastal Plain Swamp Sparrows undergo a short southerly migration to a coastal region with substantially warmer winter conditions. This study is the first to make a specific geographic prediction based on stable-isotope analysis and to test the prediction in the field.

Análisis de Isótopos Estables (C, N, H) Ayudan a Localizar la Distribución Invernal de Melospiza georgiana nigrescens
Subcolony Variation in Breeding Success in the Tufted Puffin (Fratercula Cirrhata): Association With Foraging Ecology and Implications
Authors: Hipfner J. Mark , Charette Mathieu R. , Blackburn Gwylim S.
Published: September 2019

Large-scale oceanographic processes are the main drivers of seabird breeding success, but small-scale processes, though not as well understood, can also be important. We compared the success of Tufted Puffins (Fratercula cirrhata) breeding at two subcolonies only 1.5 km apart on Triangle Island, British Columbia, Canada, 2002–2005. In addition, we used stable-isotope analysis to test the hypothesis that parental foraging strategies differed between the two subcolonies, potentially underlying the variation in breeding success. Success was concordant across years at the two sites but, overall, Tufted Puffins bred more successfully at Strata Rock than at Puffin Rock. They raised chicks in all four years at Strata Rock, but in only three years at Puffin Rock; in two of those three years, Strata Rock chicks were, on average, 60 g and 100 g heavier than Puffin Rock chicks just before fledging. Discriminant analysis of carbon and nitrogen stable-isotope ratios in egg yolk and chick blood in 2004 and 2005 indicated that parental foraging differed between the two subcolonies, with both spatial (δ13C) and trophic-level (δ15N) differences involved. Thus, our study demonstrates the existence of foraging asymmetries in a pelagic seabird at a small spatial scale (between subcolonies), complementing patterns found at larger scales (between colonies). Moreover, the foraging asymmetries were associated with inequalities in fitness measures. We conclude that small-scale processes—in this case, systematic differences in the foraging ecology of local groups—can interact with large-scale oceanographic processes to determine seabird breeding success.

Variation sous-coloniale du succès de reproduction de Fratercula cirrhata: Association avec l'écologie de la quête alimentaire et implications
Growth and Energy Requirements of Captive-Reared Common Loon (Gavia Immer) Chicks
Authors: Fournier François , Karasov William H. , Kenow Kevin P. , Meyer Michael W.
Published: September 2019

We measured the energy requirements during postnatal development of six hand-reared Common Loon (Gavia immer) chicks using continuous feeding trials and doubly labeled water. At fledging, the mean (± SE) body mass of chicks was 3,246 ± 51 g. They reached asymptotic body mass in ≈66 days and had a mean growth rate constant of 0.089 ± 0.002 day−1, which was greater than growth rate constants of other, similar-sized precocial birds. Between hatch and day 66, chicks allocated 16.5% of their metabolizable energy to new tissue, lower than the average for other bird species (20%), which might be expected considering their precocial mode of development. There was a developmental change in the assimilation efficiency of food (metabolizable energy coefficient), with a mean of 0.64 ± 0.03 in chicks aged 21 days, rising to 0.83 ± 0.07 in chicks aged 35 days.

Les besoins en énergie durant la croissance chez des jeunes Gavia immer élevés en captivité
Cooperative Display and Lekking Behavior of the Lance-Tailed Manakin (Chiroxiphia Lanceolata)
Authors: DuVal Emily H.
Published: September 2019

Male Lance-tailed Manakins (Chiroxiphia lanceolata) perform multi-male courtship displays for females. To characterize the behavioral repertoire and the lek spatial organization of this species, I observed lekking males on Isla Boca Brava, Chiriquí Province, Panamá. Breeding began in March and continued through June, though courtship displays were recorded as late as November. Males were active throughout the day at display areas on the dispersed lek. Display areas were spaced 102 ± 30 m apart and averaged 2,480 ± 1,060 m2 in area (range: 525–4,500 m2; n = 24 display areas). The behavioral repertoire of Lance-tailed Manakins included 11 dance display elements, 7 common vocalizations, and 2 types of male-male duet songs. Duet songs and multimale dances for females were cooperative efforts by male pairs and included display elements that were never performed during courtship displays by solitary males. However, males performed both cooperative and entirely solo displays for females that ended in successful copulation, which suggests that cooperation is not obligate in this species, at least on the level of individual displays. Two sonations, or nonvocal communicative sounds, were noted during courtship displays: low-amplitude pulses of noise produced in rapid sets of 7–30 clicks during slow flight displays, and a low-frequency woosh produced at the nadir of swoop displays. The Lance-tailed Manakin display repertoire provides information useful in comparative analyses of the origin and evolution of display behavior within the manakin clade and in studies of the adaptive consequences of individual behavior within this species.

Exhibición Cooperativa y Comportamiento de Asambleas de Cortejo en Chiroxiphia lanceolata
Which Life-History Components Determine Breeding Productivity for Individual Songbirds? A Case Study of the Louisiana Waterthrush (Seiurus Motacilla)
Authors: Mattsson Brady J. , Cooper Robert J.
Published: September 2019

Population dynamics of small songbirds are driven in part by fecundity and productivity (i.e., the number of young that fledge and survive the dependent stage, respectively, per adult female per year). Because of the challenges of obtaining empirical estimates for productivity or fecundity, some researchers predict fecundity using a three-factor model or more complex models such as those developed by Pease and Grzybowski (1995) or Farnsworth and Simons (2001, 2005). All these models generate a single prediction with no estimate of variability around the prediction. We developed an individual-based model that provides predictions of productivity and measurements of variability surrounding the predictions for simulated populations of Louisiana Waterthrushes (Seiurus motacilla) based on various aspects of their breeding cycle. Our empirical estimate of productivity in Louisiana Waterthrush (x̄ ± SD = 1.50 ± 1.45) was similar to that provided by our individual-based model (1.07 ± 1.24). On the basis of our model, productivity was most sensitive to and increased dramatically with increasing fledgling survival, daily nest survival, followed by nestling survival. The remaining four factors had weak, if any, effects on productivity. When compared with our individual-based model, the three-factor and Pease and Grzybowski (1995) models often produced higher predictions of fecundity, ≤2.1 additional young fledged per female. This is likely attributable to the addition of a renesting rate in our individual-based model. The Farnsworth and Simons model often produced predictions that were similar to those from our individual-based model. We believe that our individual-based model is an improvement over most existing songbird-fecundity models and can be generalized to accommodate other breeding factors, including brood parasitism and temporal variability.

¿Cuáles Componentes de la Historia de Vida Determinan la Productividad Reproductiva Individual en las Aves Canoras? Un Estudio de Caso con Seiurus motacilla
Southwestern Willow Flycatchers (Empidonax Traillii Extimus) in a Grazed Landscape: Factors Influencing Brood Parasitism
Authors: Brodhead Katherine M. , Stoleson Scott H. , Finch Deborah M.
Published: September 2019

Brood parasitism by Brown-headed Cowbirds (Molothrus ater; hereafter “cowbirds”) is an important factor contributing to the endangered status of the Southwestern Willow Flycatcher (Empidonax traillii extimus, hereafter “flycatcher”). We report on factors that influence brood parasitism on the flycatcher using seven seasons of nest data (n = 491 nests) collected in riparian patches comprising cottonwood (Populus fremontii), willow (Salix spp.), and boxelder (Acer negundo) along the Gila River in southwest New Mexico. We quantified habitat and landscape characteristics that might be associated with higher levels of parasitism and assessed the correlation between those and the observed incidence of nest parasitism. Given that cowbirds associate with cattle, we were particularly interested to determine whether the distance to active summer grazing would influence the frequency of brood parasitism. We found an apparent negative trend between the distance to grazing and brood parasitism, but this trend was not statistically significant. Rather, brood parasitism was more strongly correlated with characteristics of the habitat. Specifically, nests in larger patches, and nests built near the patch edge adjacent to the river, were more susceptible to parasitism, which suggests that these areas are preferred nesting habitat for cowbirds because of a potentially greater abundance of hosts. Parasitism was significantly lower within the core of large patches, but the insulating effect was not evident in small and medium-sized patches. Higher nest height was strongly correlated with lower probability of parasitism, most notably for nests in boxelders. Nests in boxelders were less susceptible to parasitism, whereas nests in willows were more susceptible to parasitism. We discuss the results in the context of other studies. We recommend that management efforts to recover the flycatcher should focus on increasing quality habitat, and we suggest that cattle management should focus on eliminating the adverse effects of grazing on riparian health as a more feasible option than removing cattle far enough from riparian corridors so as to preclude parasitism.

Empidonax traillii extimus en un Paisaje con Pastoreo: Factores que Influyen sobre el Parasitismo de la Nidada
Improving Estimates of Bird Density Using Multiple- Covariate Distance Sampling
Authors: Marques Tiago A. , Thomas Len , Fancy Steven G. , Buckland Stephen T.
Published: September 2019

Inferences based on counts adjusted for detectability represent a marked improvement over unadjusted counts, which provide no information about true population density and rely on untestable and unrealistic assumptions about constant detectability for inferring differences in density over time or space. Distance sampling is a widely used method to estimate detectability and therefore density. In the standard method, we model the probability of detecting a bird as a function of distance alone. Here, we describe methods that allow us to model probability of detection as a function of additional covariates—an approach available in DISTANCE, version 5.0 (Thomas et al. 2005) but still not widely applied. The main use of these methods is to increase the reliability of density estimates made on subsets of the whole data (e.g., estimates for different habitats, treatments, periods, or species), to increase precision of density estimates or to allow inferences about the covariates themselves. We present a case study of the use of multiple covariates in an analysis of a point-transect survey of Hawaii Amakihi (Hemignathus virens).

Amélioration des estimations de densité d’oiseaux par l’utilisation de l’échantillonnage par la distance avec covariables multiples
A Tody (Alcediniformes: Todidae) From The Early Oligocene of Germany
Authors: Mayr Gerald , Knopf Charles W.
Published: September 2019

We describe a postcranial skeleton of a stem-group tody (Aves: Alcediniformes: Todidae) from the early Oligocene of Germany. The fossil is tentatively assigned to Palaeotodus itardiensisMourer-Chauviré, 1985, which previously was known only from a few incomplete bones from the early Oligocene of France. It is the most substantial fossil record of a Paleogene stem-group tody described so far and shows many previously unknown skeletal details. The specimen confirms the occurrence of Todidae, which are today restricted to the Caribbean Greater Antilles, in the Paleogene of Europe. The biogeographical significance of these finds depends on the phylogenetic relationships between Todidae and other alcediniform birds. If Todidae are not the sister taxon of Momotidae (motmots) as suggested by a recent phylogenetic analysis of molecular data, occurrence of stem-group Todidae in the Old World fossil record actually follows from the currently assumed Old World origin of alcediniform birds.

Ein Todi (Alcediniformes: Todidae) aus dem unteren Oligozän Deutschlands
Survival and Habitat use of Mallard (Anas Platyrhynchos) Broods in the San Joaquin Valley, California
Authors: Chouinard Michael P. , Arnold Todd W.
Published: September 2019

The Central Valley of California is an important breeding area for Mallards (Anas platyrhynchos), but estimating recruitment rates for this population has been hampered by lack of data on duckling survival. To gain a better understanding of factors affecting brood and duckling survival, we radiomarked 56 brood hens and 112 ducklings (two per brood) on two actively managed wetland complexes in the San Joaquin Valley during 1996-1997. Total brood mortality was extensive, affecting 27 of 53 broods (51%). Survival of individual ducklings from hatching until 30 days of age was 24.8% (95% confidence interval: 0.178–0.335), with most mortality resulting from predation during the first 12 days of life. Survival differed between years and study areas but was unaffected by hatching date. Broods preferred reverse-cycle seasonal wetlands to more permanent wetlands throughout their first 30 days of life, and ducklings also had higher 2- to 30-day survival probabilities in reverse-cycle wetlands (x̄ ± SE = 0.755 ± 0.095) than in semipermanent-permanent wetlands (0.189 ± 0.056) or moist-soil units (0.173 ± 0.067). We recommend that waterfowl managers in the Central Valley provide reverse-cycle seasonal wetlands during the broodrearing period to enhance survival of locally breeding Mallards.

Supervivencia y Uso de Hábitat por Nidadas de Anas platyrhynchos en el Valle de San Joaquín, California
Systematics and Evolution in the Tityrinae (Passeriformes: Tyrannoidea)
Authors: Barber Brian R. , Rice Nathan H.
Published: September 2019

We tested the monophyly and determined the phylogenetic relationships of the seven genera (Laniisoma, Laniocera, Iodopleura, Pachyramphus, Schiffornis, Tityra, and Xenopsaris) and 27 of the 31 recognized species of the subfamily Tityrinae using complete gene sequence data from the mitochondrial gene NADH dehydrogenase subunit 2. Monophyly of all seven genera was recovered using both weighted parsimony and Bayesian methods. Intergeneric relationships were nearly identical between the two methods and are largely in concordance with previous studies. Both analyses recovered two basal clades within the Tityrinae: one clade contained Schiffornis, Laniocera, and Laniisoma; the other clade consisted of Iodopleura, Tityra, Xenopsaris, and Pachyramphus. All genera in the Tityrinae that contained multiple species were monophyletic and are concordant with current taxonomy. We present the first phylogeny for Pachyramphus and suggest that Platypsaris is not valid. Character mapping of morphological, nest-construction, and breeding-system data on our phylogeny suggest conservative evolution of most characters. We recommend elevating the Tityrinae to family level.

Sistemática y Evolución de los Tityrinae (Passeriformes: Tyrannoidea)
A Genotyping Assay to Determine Plumage Morph in The White-Throated Sparrow (Zonotrichia Albicollis)
Authors: Michopoulos Vasiliki , Maney Donna L. , Morehouse Caroline B. , Thomas James W.
Published: September 2019

In alternate plumage, the White-throated Sparrow (Zonotrichia albicollis) is polymorphic, such that individuals exhibit a median crown stripe that is either white or tan in color. This plumage polymorphism is believed to be caused by a chromosomal inversion and predicts many aspects of an individual’s aggressive and parental behavior, which makes this species an interesting and valuable subject for the study of the genetic basis of social behavior. Although the plumage polymorphism is well described, in practice the determination of morph for individual birds is not perfectly straightforward. Whereas morph can be assessed relatively easily in alternate plumage, birds in basic plumage tend to show coloration characteristic of both morphs. During the winter and fall, therefore, plumage morph cannot be determined with 100% accuracy by visual inspection alone. Here, we describe a genotyping assay that reliably predicts morph in alternate plumage. DNA from one drop of blood is amplified by PCR, digested and run on an agarose gel. The resulting banding patterns are used to distinguish white-striped from tan-striped birds with 100% accuracy. This method is fast and economical compared with karyotyping, is far less subjective than assessment of morph by plumage characteristics, and can be performed using any kind of sample from which DNA can be extracted.

Un test génotypique pour déterminer la forme du plumage chez Zonotrichia albicollis
Female-Biased Sex Ratio Arises After Parental Care in The Sexually Dimorphic Waved Albatross (Phoebastria Irrorata)
Authors: Awkerman Jill A. , Westbrock Mark A. , Huyvaert Kathryn P. , Anderson David J.
Published: September 2019

In response to evidence of sexual segregation at foraging grounds as well as male-biased band recoveries, we investigated the ontogeny of the female- biased adult sex ratio in the Waved Albatross (Phoebastria irrorata), an IUCN “critically endangered species” essentially endemic to Isla Española, Galapagos, Ecuador. Using a molecular technique to determine the sex of chicks and adults and known fate analysis of chicks during rearing, we found no evidence of a sex-ratio bias at hatching or fledging in three consecutive years with variable reproductive success. Although male chicks were significantly larger than females at fledging, survival to fledging of a large sample of male and female chicks did not differ. The sex ratio among a cohort of young adults at approximately the age of first breeding (eight years) also did not differ significantly from parity. Differential adult mortality, including male-biased mortality in fisheries, is the most probable cause of a female- biased population sex ratio, and is at least partially responsible for an apparent reduction in the number of breeding pairs of this species.

El Albatros Phoebastria irrorata, una Especie con Dimorfismo Sexual, Presenta una Mayor Proporción de Hembras Luego del Cuidado Parental
Time Since Contact and Gene Flow May Explain Variation in Hybrid Frequencies Among Three Dendroica Townsendi × D. Occidentalis (Parulidae) Hybrid Zones
Authors: Rohwer Sievert , Martin Paul R.
Published: September 2019

Hermit Warblers (Dendroica occidentalis) and Townsend’s Warblers (D. townsendi) meet and hybridize in three replicate zones in Washington and Oregon. Using male specimens, we show that the ratio of hybrid to parental phenotypes varies systematically across these three zones: there were 60.4% hybrids among 96 males from the Olympic zone, 43.3% hybrids among 411 males from the Washington Cascade zone, and 27.8% hybrids among 209 males from the Oregon Cascade zone. We found no evidence of habitat or climatic factors driving these systematic differences in hybrid frequencies, and we argue that they are related to differences among these zones in the immigration of pure parentals and time since contact. Building on earlier hypotheses about massive movement of the coastal zones (Rohwer and Wood 1998), we can infer that the Olympic and Washington Cascade zones are old and of similar age. The Washington Cascade zone, but not the Olympic zone, receives Townsend’s immigrants from the Rocky Mountains through the Okanogan high- lands, as shown by the linkage analyses in Rohwer et al. (2001). This immigration apparently accounts for the lower frequency of hybrids in the Washington Cascades. The Washington Cascade and Oregon Cascade zones are both situated adjacent to forest corridors that connect them to the Rocky Mountains to the east, so both of these zones should receive Townsend’s immigrants from the east (linkage analyses have yet to be done for the Oregon Cascades because the mitochondrial DNA haplo- types for these specimens have not been determined). The Washington Cascade zone, however, is old, whereas the Oregon Cascade zone appears to have been established only recently in response to anthropogenic habitat changes, which accounts for its low frequency of hybrids. We are unaware of any other replicate set of hybrid zones where differences in time since contact and dispersal have been related to variation in hybrid frequencies.

El Tiempo Transcurrido desde el Contacto y el Flujo Genético Podrían Explicar la Variación en la Frecuencia de los Híbridos entre Tres Zonas de Hibridación entre Dendroica townsendi y D. occidentalis (Parulidae)
Guidelines for Using Double Sampling in Avian Population Monitoring
Authors: Collins Brian T.
Published: September 2019

Double sampling involves combining information from inexpensive rapid counts with intensive complete counts to provide an efficient population estimate. This technique is a valuable approach for calibrating population indices based on incomplete counts and improving the precision of monitoring studies. Data collected through a double-sampling protocol can be analyzed with either a ratio or a regression estimator. The ratio estimator is recommended when the relationship of the actual count to the rapid count is a straight line through origin, which may not be valid when surveying populations that have a small number of individuals per site and a low detection probability. In such situations, the regression estimator may be more appropriate. I investigated the properties of these two different estimators through a simulation study and tabulated sample sizes to control bias of the population average and standard error. Further, I used the results to evaluate when double sampling is a cost-effective design and how to design surveys that meet precision requirements. The design process is illustrated with the Spring Eastern Waterfowl Survey, which shows that double sampling is not always appropriate.

Directives pour l’utilisation de l’échantillonnage double dans le suivi des populations d’oiseaux
Local Annual Survival and Seasonal Residency Rates of Semipalmated Sandpipers (Calidris Pusilla) in Puerto Rico
Authors: Rice Susan M. , Collazo Jaime A. , Alldredge Mathew W. , Harrington Brian A. , Lewis Allen R.
Published: September 2019

We report seasonal residency and local annual survival rates of migratory Semipalmated Sandpipers (Calidris pusilla) at the Cabo Rojo salt flats, Puerto Rico. Residency rate (daily probability of remaining on the flats) was 0.991 ± 0.001 (x̄ ± SE), yielding a mean length of stay of 110 days. This finding supports the inclusion of the Caribbean as part of the species' winter range. Average estimated percentage of fat was low but increased throughout the season, which suggests that birds replenish some spent fat reserves and strive for energetic maintenance. Local annual survival rate was 0.62 ± 0.04, within the range of values reported for breeding populations at Manitoba and Alaska (0.53–0.76). The similarity was not unexpected because estimates were obtained annually but at opposite sites of their annual migratory movements. Birds captured at the salt flats appeared to be a mix of birds from various parts of the breeding range, judging from morphology (culmen's coefficient of variation = 9.1, n = 106). This suggested that origin (breeding area) of birds and their proportion in the data should be ascertained and accounted for in analyses to glean the full conservation implications of winter-based annual survival estimates. Those data are needed to unravel the possibility that individuals of distinct populations are affected by differential mortality factors across different migratory routes. Mean length of stay strongly suggested that habitat quality at the salt flats was high. Rainfall and tidal flow combine to increase food availability during fall. The salt flats dry up gradually toward late January, at the onset of the dry season. Semipalmated Sandpipers may move west to other Greater Antilles or south to sites such as coastal Surinam until the onset of spring migration. They are not an oversummering species at the salt flats. Conservation efforts in the Caribbean region require understanding the dynamics of this species throughout winter to protect essential habitat.

Tasas de Supervivencia Anual Local y de Residencia Estacional de Calidris pusilla en Puerto Rico
Factors Associated With Variation in Home-Range Size of Appalachian Ruffed Grouse (Bonasa Umbellus)
Authors: Whitaker Darroch M. , Stauffer Dean F. , Norman Gary W. , Devers Patrick K. , Edwards John , Giuliano William M. , Harper Craig , Igo William , Sole Jeff , Spiker Harry , Tefft Brian
Published: September 2019

From 1996 to 2001, researchers at 10 Appalachian study sites collected radiotracking data sufficient to delineate 1,054 seasonal home ranges of Ruffed Grouse (Bonasa umbellus; hereafter “grouse”). Using information-theoretic model selection and paired comparison of home ranges from individual grouse, we evaluated individual, local, and landscape factors hypothesized to affect grouse home-range size. Females and juvenile males occupied home ranges that averaged >2× larger than those of adult males, and home ranges of females averaged 2.6× larger during successful breeding seasons than during years of reproductive failure. Clearcuts and forest roads are considered high-quality covers, and both were more prevalent in smaller home ranges. Several factors operating at a regional and landscape scale were also important. Previous studies have reported that southern grouse use relatively large home ranges, and we observed a continuous decline in home-range size with increasing latitude across the 710-km range spanned by our study sites. Home-range size of males, particularly juvenile males, was positively related to an index of population density. Given the species' “dispersed lekking” mating system, we interpret this as evidence of competition for preferred display sites. As has been reported for other game birds, all sex and age classes of grouse used smaller home ranges following closure of sites to hunting. Grouse inhabiting oak-hickory forests used larger home ranges than conspecifics in mixed mesophytic forests, and other factors interacted with forest type. In oak-hickory forests, female home-range size was inversely related to use of mesic bottomlands, which support important forage plants, and home ranges of adult grouse increased 2.5× following poor hard-mast crops. By contrast, home ranges of grouse inhabiting mixed mesophytic forests were unrelated to use of bottomlands, and the influence of hard mast was reduced. This is in line with the view that in Appalachian oak-hickory forests, grouse are under strong nutritional constraint. However, this constraint is reduced in mixed mesophytic forests, likely because of the presence of high-quality alternative foods (e.g., cherry [Prunus spp.] and birch [Betula spp.]).

Facteurs associés à une variation de la taille du domaine vital de Bonasa umbellus dans les Appalaches
Habitat Partitioning of Four Sympatric Thrush Species at Three Spatial Scales on a Managed Forest in West Virginia
Authors: Dellinger Rachel L. , Wood Petra Bohall , Keyser Patrick D. , Seidel George
Published: September 2019

Four thrush species are sympatric in the central Appalachians: Veery (Catharus fuscescens), Hermit Thrush (C. guttatus), Wood Thrush (Hylocichla mustelina), and American Robin (Turdus migratorius). The four species often nest near one another, which suggests that habitat partitioning may have developed to minimize past interspecific competition. Our objectives were to determine which specific characteristics of nesting habitat were partitioned among the species and to evaluate the relationship of these characteristics to nest survival. We monitored nests and sampled habitat variables at three spatial scales: nest substrate, nest site, and territory. A multivariate analysis of variance indicated a difference (P < 0.01) in the nest sites of all species and in each pairwise species contrast. An analysis of variance and Fisher’s exact tests detected differences (P < 0.05) among species in 21 of 36 variables measured. Classification tree analysis correctly classified nests by species at a rate better than would be expected at random. Habitat partitioning among the four thrush species occurred at all three scales sampled, with the most important partitioning variables being nest height, distance-to-edge, sapling density, and elevation. Mayfield logistic regression found a positive relationship (P < 0.05) between decreasing nest height and American Robin nest survival. Overall, nest survival was similar among the four thrush species examined, and most of the variables that we measured were unrelated to survival.

Partition de l’habitat de quatre espèces sympatriques de grives à trois échelles spatiales dans une forêt aménagée de la Virginie-Occidentale
Ecology and Behavior of Chickadees and Titmice: An Integrated Approach
Authors: Brennan Leonard A.
Published: September 2019

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.
Glorified Dinosaurs: The Origin and Early Evolution of Birds
Authors: Houde Peter
Published: September 2019

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.
Linking men's voice pitch to actual and perceived trustworthiness across domains
Authors: Schild Christoph , Stern Julia , Zettler Ingo
Published: September 2019

Previous research suggests that judgments about a male speaker's trustworthiness vary due to the speaker's voice pitch (mean F0) and differ across domains. However, mixed results in terms of the direction and extent of such effects have been reported. Moreover, no study so far has investigated whether men's mean F0 is, indeed, a valid cue to their self-reported and behavioral trustworthiness, and whether trustworthiness judgments are accurate. We tested the relation between mean F0 and actual general, economic, and mating-related trustworthiness in 181 men, as well as trustworthiness judgments of 95 perceivers across all three domains. Analyses show that men's mean F0 is not related to Honesty–Humility (as a trait indicator of general trustworthiness), trustworthy intentions, or trust game behavior, suggesting no relation of mean F0 to general or economic trustworthiness. In contrast, results suggest that mean F0 might be related to mating-related trustworthiness (as indicated by self-reported relationship infidelity). However, lower mean F0 was judged as more trustworthy in economic but less trustworthy in mating-related domains and rather weakly related to judgments of general trustworthiness. Trustworthiness judgments were not accurate for general or economic trustworthiness, but exploratory analyses suggest that women might be able to accurately judge men's relationship infidelity based on their voice pitch. Next to these analyses, we report exploratory analyses involving and controlling for additional voice parameters.
QUBIC2: a novel and robust biclustering algorithm for analyses and interpretation of large-scale RNA-Seq data
Authors: Xie Juan , Ma Anjun , Zhang Yu , Liu Bingqiang , Cao Sha , Wang Cankun , Xu Jennifer , Zhang Chi , Ma Qin
Published: September 2019

Motivation

The biclustering of large-scale gene expression data holds promising potential for detecting condition-specific functional gene modules (i.e. biclusters). However, existing methods do not adequately address a comprehensive detection of all significant bicluster structures and have limited power when applied to expression data generated by RNA-Sequencing (RNA-Seq), especially single-cell RNA-Seq (scRNA-Seq) data, where massive zero and low expression values are observed.

Results

We present a new biclustering algorithm, QUalitative BIClustering algorithm Version 2 (QUBIC2), which is empowered by: (i) a novel left-truncated mixture of Gaussian model for an accurate assessment of multimodality in zero-enriched expression data, (ii) a fast and efficient dropouts-saving expansion strategy for functional gene modules optimization using information divergency and (iii) a rigorous statistical test for the significance of all the identified biclusters in any organism, including those without substantial functional annotations. QUBIC2 demonstrated considerably improved performance in detecting biclusters compared to other five widely used algorithms on various benchmark datasets from E.coli, Human and simulated data. QUBIC2 also showcased robust and superior performance on gene expression data generated by microarray, bulk RNA-Seq and scRNA-Seq.

Availability and implementation

The source code of QUBIC2 is freely available at https://github.com/OSU-BMBL/QUBIC2.

Supplementary information

Supplementary data are available at Bioinformatics online.
Echiniscus virginicus complex: the first case of pseudocryptic allopatry and pantropical distribution in tardigrades
Authors: Gąsiorek Piotr , Jackson Kathy J , Meyer Harry A , Zając Krzysztof , Nelson Diane R , Kristensen Reinhardt M , Michalczyk Łukasz
Published: September 2019

Mainly because of the problems with species delineation, the biogeography of microscopic organisms is notoriously difficult to elucidate. In this contribution, variable nuclear and mitochondrial DNA markers were sequenced from individual specimens representing the Echiniscus virginicus complex that are morphologically indistinguishable under light microscopy (five populations from the temperate Eastern Nearctic and 13 populations from the subtropical and tropical zone). A range of methods was used to dissect components of variability within the complex (Bayesian inference, haplotype networks, Poisson tree processes, automatic barcode gap discovery delineations, principal components analysis and ANOVA). We found deep divergence between the temperate Eastern Nearctic E. virginicus and pantropical Echiniscus lineatus in all three genetic markers. In contrast, intraspecific genetic variation was very low, regardless of the geographical distance between the populations. Moreover, for the first time, statistical predictions of tardigrade geographical distributions were modelled. The factor determining the allopatric geographical ranges of deceptively similar species analysed in this study is most likely to be the type of climate. Our study shows that widespread tardigrade species exist, and both geographical distribution modelling and the genetic structure of populations of the pantropical E. lineatus suggest wind-mediated (aeolian) passive long-distance dispersal.
Biological interpretations of the biphasic model of ontogenetic brain–body allometry: a reply to Packard
Authors: Tsuboi Masahito
Published: September 2019

Allometry is a description of organismal growth. Historically, a simple power law has been used most widely to describe the rate of growth in phenotypic traits relative to the rate of growth in overall size. However, the validity of this standard practice has repeatedly been criticized. In an accompanying opinion piece, Packard reanalysed data from a recent study on brain–body ontogenetic allometry and claimed that the biphasic growth model suggested in that study was an artefact of logarithmic transformation. Based on the model selection, Packard proposed alternative hypotheses for brain–body ontogenetic allometry. Here, I examine the validity of these models by comparing empirical data on body sizes at two critical neurodevelopmental events in mammals, i.e. at birth and at the time of the peak rate of brain growth, with statistically inferred body sizes that are supposed to characterize neurodevelopmental processes. These analyses support the existence of two distinct phases of brain growth and provide weak support for Packard's uniphasic model of brain growth. This study demonstrates the importance of considering alternative models in studies of allometry, but also highlights that such models need to respect the biological theoretical context of allometry.
Atomoxetine and citalopram alter brain network organization in Parkinson’s disease
Authors: Borchert Robin J , Rittman Timothy , Rae Charlotte L , Passamonti Luca , Jones Simon P , Vatansever Deniz , Vázquez Rodríguez Patricia , Ye Zheng , Nombela Cristina , Hughes Laura E , Robbins Trevor W , Rowe James B
Published: September 2019

Parkinson’s disease has multiple detrimental effects on motor and cognitive systems in the brain. In contrast to motor deficits, cognitive impairments in Parkinson’s disease are usually not ameliorated, and can even be worsened, by dopaminergic treatments. Recent evidence has shown potential benefits from restoring other neurotransmitter deficits, including noradrenergic and serotonergic transmission. Here, we study global and regional brain network organization using task-free imaging (also known as resting-state), which minimizes performance confounds and the bias towards predetermined networks. Thirty-three patients with idiopathic Parkinson’s disease were studied three times in a double-blinded, placebo-controlled counter-balanced crossover design, following placebo, 40 mg oral atomoxetine (selective noradrenaline reuptake inhibitor) or 30 mg oral citalopram (selective serotonin reuptake inhibitor). Neuropsychological assessments were performed outside the scanner. Seventy-six controls were scanned without medication to provide normative data for comparison to the patient cohort. Graph theoretical analysis of task-free brain connectivity, with a random 500-node parcellation, was used to measure the effect of disease in placebo-treated state (versus unmedicated controls) and pharmacological intervention (drug versus placebo). Relative to controls, patients on placebo had executive impairments (reduced fluency and inhibitory control), which was reflected in dysfunctional network dynamics in terms of reduced clustering coefficient, hub degree and hub centrality. In patients, atomoxetine improved fluency in proportion to plasma concentration (P = 0.006, r2 = 0.24), and improved response inhibition in proportion to increased hub Eigen centrality (P = 0.044, r2 = 0.14). Citalopram did not improve fluency or inhibitory control, but its influence on network integration and efficiency depended on disease severity: clustering (P = 0.01, r2 = 0.22), modularity (P = 0.043, r2 = 0.14) and path length (P = 0.006, r2 = 0.25) increased in patients with milder forms of Parkinson’s disease, but decreased in patients with more advanced disease (Unified Parkinson’s Disease Rating Scale motor subscale part III > 30). This study supports the use of task-free imaging of brain networks in translational pharmacology of neurodegenerative disorders. We propose that hub connectivity contributes to cognitive performance in Parkinson’s disease, and that noradrenergic treatment strategies can partially restore the neural systems supporting executive function.
Mortality after amputation in dialysis patients is high but not modified by diabetes status
Authors: Schroijen Marielle A , van Diepen Merel , Hamming Jaap F , Dekker Friedo W , Dekkers Olaf M
Published: September 2019

Background

Survival among dialysis patients with diabetes mellitus (DM) is inferior to survival of non-diabetic dialysis patients, probably due to the higher prevalence of diabetes-related comorbid conditions. One could hypothesize that these comorbid conditions also contribute to a decreased survival after amputation in diabetic patients compared with non-diabetic patients on dialysis.

Methods

Data were collected from the Netherlands Cooperative Study on the Adequacy of Dialysis, a multicentre, prospective cohort study in which new patients with end-stage renal disease were monitored until transplantation or death. Amputation rates (incident cases) were calculated in patients with and without DM. The primary endpoint was all-cause survival after first amputation during dialysis therapy in diabetic patients compared with non-diabetic dialysis patients with an amputation. This was formally assessed using interaction analysis (Poisson regression).

Results

During follow-up (mean duration 2.9 years), 50 of the 413 diabetic patients had a new amputation (12.1%), compared with 20 of 1553 non-diabetic patients (1.2%). Amputation rates/1000 person-years were 47.9 [95% confidence interval (CI) 36.3–63.2] and 4.1 (95% CI 2.7–6.4), respectively, for diabetic patients and non-diabetic patients. Amputation increased mortality risk more than 4-fold in patients without diabetes [hazard ratio (HR) 4.6 (95% CI 2.8–7.6)] as well as in patients with diabetes [HR 4.6 (95% CI 3.3–6.4)]. No formal interaction between diabetes and amputation was found (P = 0.12).

Conclusions

Amputation in dialysis patients is associated with a 4-fold increased mortality risk; this mortality risk was similar for diabetes and non-diabetes patients. Importantly, the risk for amputation is 10-fold higher in DM compared with non-diabetic dialysis patients.
Post-Release Survival of Hand-Reared and Parent-Reared Mississippi Sandhill Cranes
Authors: Ellis David H. , Gee George F. , Hereford Scott G. , Olsen Glenn H. , Chisolm T. David , Nicolich Jane M. , Sullivan Kathleen A. , Thomas Nancy J. , Nagendran Meenakshi , Hatfield Jeff S.
Published: September 2019

The Mississippi Sandhill Crane (Grus canadensis pulla) reintroduction program is the largest crane reintroduction effort in the world. Here we report on a 4-year experiment in which we compared post-release survival rates of 56 hand-reared and 76 parent-reared Mississippi Sandhill Cranes. First-year survival was 80%. Surprisingly, hand-reared cranes survived better than parent-reared birds, and the highest survival rates were for hand-reared juveniles released in mixed cohorts with parent-reared birds. Mixing improved survival most for parent-reared birds released with hand-reared birds. These results demonstrate that hand-rearing can produce birds which survive at least as well as parent-reared birds and that improved survival results from mixing hand-reared and parent-reared birds.
Behavior, Diet, and Breeding Biology of Double-Toothed Kites at a Guatemalan Lowland Site
Authors: Schulze Mark D. , CÓrdova Jose LuÍs , Seavy Nathaniel E. , Whitacre David F.
Published: September 2019

We studied Double-toothed Kites (Harpagus bidentatus) in tropical lowland forest at Tikal National Park, Petén, Guatemala, documenting behavior and diet during the incubation and nestling periods. These 200-g kites are Accipiter-like in form and strikingly size-dimorphic for a kite. Modal clutch size was two, producing 0.63 fledglings per nesting attempt and 1.25 per successful nest. Nesting was largely synchronous among pairs, with hatching during the first month of the rainy season and fledging one month later. Incubation lasted 42–45 days and nestlings fledged at 29.5 days on average. A radio-tagged fledgling was fed near the nest for 35 days; 6–8 weeks after fledging it dispersed at least 10 km, presumably reaching independence. Males did not incubate or brood, and rarely fed nestlings directly. Males typically provided most but not all prey (mainly lizards) during incubation and early nestling periods. Insects in the nestling diet increased through the nestling period as females increasingly hunted, often bringing in insects. These kites hunted from perches, below and within the closed canopy of tall, mature forest, taking 60.5% insects, 38.1% lizards, and 1.4% other vertebrates; vertebrates comprised at least 75% of prey biomass. Most prey were taken from vegetation, but prey in flight also were captured. Active, adjacent nests averaged 1.35 km apart, for a maximum density estimate of 0.60 pairs km−2 and a more likely estimate of 0.33–0.50 pairs km−2 in homogeneous, favorable habitat and 0.29–0.44 pairs km−2 for Tikal National Park as a whole.