bluuebunny/crossref_metadata_2025_split huggingface dataset:
Annual Survival Rates of Wintering Sparrows: Assessing Demographic Consequences of Migration
Authors: Sandercock Brett K. , Jaramillo Alvaro 
Published: September 2019

AbstractThe demographic consequences of migration have important implications for both evolutionary ecology and conservation biology. We investigated local survival rates for six populations of sparrows at a wintering site. Recent developments in mark–recapture statistics were applied to a 13 year dataset with large numbers of marked individuals (n = 1,632 to 4,394). The study taxa were closely related, and included one resident species (Song Sparrow [Melospiza melodia gouldii]), one short-distance migrant (“Puget Sound” White-crowned Sparrow [Zonotrichia leucophrys pugetensis]), two moderate-distance migrants (Lincoln's [Melospiza lincolnii] and Fox [Passerella iliaca] sparrow), and two long-distance migrants (“Gambel's” White-crowned [Zonotrichia leucophrys gambelii] and Golden-crowned [Zonotrichia atricapilla] sparrow). A literature review demonstrated a cline in fecundity among these sparrows: resident and short-distance migrants laid multiple clutches of few eggs, whereas long-distance migrants tended to produce one large clutch. Annual rates of local survival were low in the interval after first capture (<0.35), possibly because of variation in true survival, site-fidelity, presence of transients and heterogeneity of capture. Estimates of local survival among birds that returned at least once were more robust and were comparable among Song (0.558 ± 0.054 SE), Puget Sound White-crowned (0.461 ± 0.026), Lincoln's (0.456 ± 0.066), Fox (0.352 ± 0.0), Golden-crowned (0.422 ± 0.023) and Gambel's White-crowned (0.432 ± 0.0) sparrows. Estimates of survivorship for Lincoln's and Fox sparrows are among the first values available for those species. Local survival was not higher among resident than migratory taxa, nor did it covary with migration distance among migratory species. These results did not support the time-allocation hypothesis of Greenberg (1980), but are consistent with aspects of bet-hedging theory. While these analyses have potential implications for conservation of migratory birds, further work is required to establish whether these patterns are applicable to Neotropical migrants.
Scales of Food Availability for an Endangered Insectivore, The Hawaii Akepa
Authors: Fretz J. Scott 
Published: September 2019

Abstract
The Hawaii Akepa (Loxops coccineus coccineus) is an endangered bird that has declined dramatically in the last 100 years, and is now rare or absent from many areas that appear to support suitable habitat. Food availability may play a role in these distribution patterns, but differences in food between sites may arise from different sources. I compared prey availability between a site supporting a large, stable Hawaii Akepa population, and a site from which Hawaii Akepa have declined in the last 100 years for unknown reasons. I used three spatial scales to compare food between sites to explore the basis of differences in food between sites. At a scale appropriate for comparing prey population dynamics (scale 1), I found that prey population densities are similar between sites, suggesting that introduced (or native) predators or parasitoids have not affected prey populations differently between sites. At two larger scales incorporating habitat structure, I found that food availability is much lower at the site of Hawaii Akepa declines. Differences in canopy density per square meter (scale 2), and in canopy cover per square kilometer (scale 3), result in lower food availability that may have effects on individual foraging birds as well as on potential Hawaii Akepa population density. These findings illustrate the importance of explicitly incorporating spatial scale into inquiries about food for Hawaii Akepa, and suggest that the site of population declines may not be suitable habitat with respect to food for this species.
Plasma Amino Acid Concentrations as an Indicator of Protein Availability to Breeding Herring Gulls (Larus Argentatus)
Authors: Hebert Craig E. , Shutt J. Laird , Ball Ron O. 
Published: September 2019

AbstractIn a captive-feeding study using Herring Gulls (Larus argentatus), plasma amino-acid concentrations increased in response to an increase in dietary protein. Plasma amino-acid concentrations were also measured in wild Herring Gulls captured during incubation at eight Laurentian Great Lakes colonies. Those concentrations were used as an indicator of protein availability at those locations. Significant differences in amino acid concentrations were observed among colonies. Lower amino acid levels, particularly of the essential amino acids, were measured in gulls nesting on Lake Superior, whereas values in gulls captured on Lake Ontario and Lake Erie were greater. Those geographic differences in protein availability likely reflected spatial differences in availability of high quality prey (e.g. fish). Geographic differences in prey availability probably affected diet composition. Comparison of amino-acid levels in wild birds to reference values obtained through the captive feeding study indicated that gulls nesting on Lake Superior may have been protein limited. Colony-wide estimates of adult female body condition, intraclutch variation in egg size, and productivity were correlated with an index of plasma amino-acid concentrations.
Effects of Feather Lice on Flight Behavior of Male Barn Swallows (Hirundo Rustica)
Authors: Barbosa A. , Merino S. , Lope Fde , Møller A. P. 
Published: September 2019

AbstractParasites may affect host behavior in a number of ways, including their locomotory performance. We investigated whether the number of holes produced by the feather louse (Myrsidea rustica) affected flight behavior in adult male Barn Swallows (Hirundo rustica) by video-taping flight performance of individuals during escape and level flight. Percentage of time spent flapping during foraging flight was positively related to number of holes, but not to other flight parameters such as wingbeat frequency. These results suggest indirect effects of feather lice on host performance that must be considered together with effects of thermoregulation and feather breakage. This is the first report of an effect of parasite load on flight behavior.
Genetic Parentage and Mate Guarding in the Arctic-Breeding Western Sandpiper
Authors: Blomqvist Donald , Kempenaers Bart , Lanctot Richard B. , Sandercock Brett K. 
Published: September 2019

AbstractExtrapair copulations and fertilizations are common among birds, especially in passerines. So far, however, few studies have examined genetic mating systems in socially monogamous shorebirds. Here, we examine parentage in the Western Sandpiper (Calidris mauri). Given that Western Sandpipers nest at high densities on the Arctic tundra, have separate nesting and feeding areas, and show high divorce rates between years, we expected extrapair paternity to be more common in this species compared to other monogamous shorebirds. However, DNA fingerprinting of 98 chicks from 40 families revealed that only 8% of broods contained young sired by extrapair males, and that 5% of all chicks were extrapair. All chicks were the genetic offspring of their social mothers. We found that males followed females more often than the reverse. Also, cuckolded males were separated from their mates for longer than those that did not lose paternity. Although these results suggest a role for male mate guarding, we propose that high potential costs in terms of reduced paternal care likely constrain female Western Sandpipers from seeking extrapair copulations.
Habitat use and Breeding Distribution of Magellanic Penguins in Northern San Jorge Gulf, Patagonia, Argentina
Authors: Borboroglu Pablo García , Yorio Pablo , Boersma P. Dee , Valle Héctor Del , Bertellotti Marcelo 
Published: September 2019

Abstract
We evaluated distribution and size of Magellanic Penguin (Spheniscus magellanicus) colonies in northern San Jorge Gulf, Argentina, characterizing nesting habitat at 14 islands with colonies (IC) and 28 islands without nesting penguins (INC). Digital analysis of a Landsat TM satellite image and field measurements were used to assess vegetation and substrate. The 14 breeding colonies ranged in size from 13 to 96,300 nests, and number of breeding pairs was estimated at 218,460. Colonies were only located on islands. Digital analysis of the satellite image showed that the proportion of area with shrub–steppe vegetation was significantly higher at IC than at INC (38.6 vs. 4.9%), whereas percentage of rocky substrate was lower at IC (33.6 vs. 64.8%). Percentage of vegetation cover was positively correlated with island area and with number of breeding pairs. Most nests (98.6%) were located under bushes, whereas the rest were burrows dug into the substrate. Mean size of bushes used for nesting was higher at IC (4.47 vs. 0.99 m2) as was the percentage of silt–clay substrate (47.31 vs. 1.98%). Coast minimum slopes at INC were steeper than the slopes of entrance routes at IC (27.6 vs. 5.7°). Probability of occupation of islands increased with amount of shrub-type vegetation cover and silt–clay substrate, and decreased with increasing slopes and amount of sandy substrate. Magellanic Penguins selected islands with shrub-type vegetation and soil that allow building nests with adequate cover. These results are consistent with other studies showing vegetation cover is an important nesting requirement for Magellanic Penguins.
Effects of Hardwood Reduction on Winter Birds in Northwest Florida Longleaf Pine Sandhill Forests
Authors: Provencher Louis , Gobris Nancy M. , Brennan Leonard A. 
Published: September 2019

Abstract
Reversing decades of fire exclusion by hardwood midstory reduction is now used to recover populations of the federally endangered Red-cockaded Woodpecker (Picoides borealis) in longleaf pine (Pinus palustris) forest ecosystems. The effects of Red-cockaded Woodpecker management on winter birds in longleaf pine sandhill forests are largely unknown. Examining habitat use of winter migrants, some of which are declining, may influence the selection of habitat management techniques used for Red-cockaded Woodpeckers to benefit overwintering migrants. During the winters (December–February) of 1997–1998 and 1998–1999, we tested experimentally the effects of hardwood reduction treatments applied in 1995 on winter birds at Eglin Air Force Base in fire-excluded northwest Florida longleaf pine sandhills. Treatments were (1) prescribed spring burning, (2) herbicide application, (3) mechanical felling and girdling, and (4) a control where decades of fire exclusion was maintained. We also sampled winter bird flocks in frequently burned, nonexperimental reference plots to measure management success. Hardwood reduction techniques had no effect on flock species richness, which averaged 7.9 and 7.2, respectively, during 1997–1998 and 1998–1999. Larger flocks in felling and girdling and in herbicide plots were primarily due to significantly higher numbers of overwintering Chipping Sparrows (Spizella passerina), as well as resident Red-cockaded Woodpeckers and an influx of temperate migrant Pine Warblers (Dendroica pinus). In contrast, flocks in control plots were smaller (flock size and species composition in spring burn plots were intermediate) and composed of hardwood-associated species, such as Tufted Titmouse (Baeolophus bicolor) and Carolina Chickadee (Poecile carolinensis). The relative uses of longleaf pines and hardwoods by Red-cockaded Woodpeckers, Pine Warblers, and Brown-headed Nuthatches (Sitta pusilla) during both winters best explained that winter birds present in herbicide, felling and girdling, and reference plots were more likely to forage on the same tree species and substrates than birds in spring-burned plots, and least likely to forage on the same species and substrates as birds in the control plots. Those differences corresponded to the following increasing order of hardwood stem mortality among treatments: control, spring burn (41%), felling and girdling (62%), and herbicide (92%). Repeated burning is recommended to restore the reference foraging condition because it was eight times less expensive than other techniques, which favored mostly Chipping Sparrows.
Mexican Spotted Owl (Strix Occidentalis) Population Dynamics: Influence of Climatic Variation on Survival and Reproduction
Authors: Seamans Mark E. , Gutiérrez R. J. , May Christopher A. 
Published: September 2019

AbstractUnderstanding the mechanisms causing temporal variability in demographic parameters is essential to understanding fluctuations in populations. As part of a long-term demographic study, we evaluated influence of climate on Mexican Spotted Owl (Strix occidentalis lucida) annual survival and reproduction in two study areas, one in Arizona and one in New Mexico. Spotted Owl survival in New Mexico and reproductive output in both study areas were positively related to total amounts of precipitation from the previous year, previous winter, or monsoon season. For both study areas, temporal process variation in reproductive output (CV[R] = 51.2 and 75.2% for Arizona and New Mexico, respectively) was greater than that for survival (CV[ϕ] = 12.9 and 7.1% for Arizona and New Mexico, respectively). Precipitation from the previous year explained 73% of σ̂2temporal reproductive output for Arizona owls and precipitation from the previous monsoon explained 42% of σ̂2temporal in reproductive output for New Mexico owls. Precipitation from the previous monsoon season explained 53% of σ̂2temporal in Arizona owl survival and precipitation from the previous winter explained 56% of σ̂2temporal in New Mexico owl survival. The two populations of Spotted Owls we studied appeared to have the same life-history strategy hypothesized for a population of Northern Spotted Owls (S. o. caurina), although the Mexican subspecies apparently responded quite differently to climatic variation.
Intromittent Organ Morphology and Testis Size in Relation to Mating System in Waterfowl
Authors: Coker Christopher R. , McKinney Frank , Hays Helen , Briggs Susan V. , Cheng Kimberly M. 
Published: September 2019

AbstractThe waterfowl family Anatidae is one of very few avian taxa that possesses an intromittent organ. This paper examines the adaptive significance of the intromittent organ in waterfowl by determining the relationships between intromittent organ morphology and the intensity of sperm competition (as reflected by frequency of forced extrapair copulations [FEPCs]). Intromittent organ morphological characteristics, including length and circumference (adjusted for body size), number of ridges and knobs (per unit area), ridge or knob height, ridge or knob span, and area covered by ridges and knobs, were measured from scaled drawings of museum specimens of 54 waterfowl species (33 genera), 27 of which were ranked by frequency of FEPC (1 = monogamous, 2 = rare FEPC, 3 = frequent FEPC, and 4 = polygynous or promiscuous). Testes sizes were also investigated in relation to FEPCs, where testes mass (adjusted for body size) from 44 species (24 genera) were obtained (29 species with mating strategies). The size of the testes, the length of the intromittent organ, the height of the intromittent organ ridges and knobs, and the area covered by ridges and knobs increased significantly with the frequency of FEPC, and those relationships exist after correcting for common ancestry constraints. These results are consistent with the hypothesis that waterfowl intromittent organs are involved in sperm competition. Further research into the actual mechanism by which the intromittent organ is involved would be worthwhile.
A Removal Model for Estimating Detection Probabilities From Point-Count Surveys
Authors: Farnsworth George L. , Pollock Kenneth H. , Nichols James D. , Simons Theodore R. , Hines James E. , Sauer John R. 
Published: September 2019

AbstractUse of point-count surveys is a popular method for collecting data on abundance and distribution of birds. However, analyses of such data often ignore potential differences in detection probability. We adapted a removal model to directly estimate detection probability during point-count surveys. The model assumes that singing frequency is a major factor influencing probability of detection when birds are surveyed using point counts. This may be appropriate for surveys in which most detections are by sound. The model requires counts to be divided into several time intervals. Point counts are often conducted for 10 min, where the number of birds recorded is divided into those first observed in the first 3 min, the subsequent 2 min, and the last 5 min. We developed a maximum-likelihood estimator for the detectability of birds recorded during counts divided into those intervals. This technique can easily be adapted to point counts divided into intervals of any length. We applied this method to unlimited-radius counts conducted in Great Smoky Mountains National Park. We used model selection criteria to identify whether detection probabilities varied among species, throughout the morning, throughout the season, and among different observers. We found differences in detection probability among species. Species that sing frequently such as Winter Wren (Troglodytes troglodytes) and Acadian Flycatcher (Empidonax virescens) had high detection probabilities (∼90%) and species that call infrequently such as Pileated Woodpecker (Dryocopus pileatus) had low detection probability (36%). We also found detection probabilities varied with the time of day for some species (e.g. thrushes) and between observers for other species. We used the same approach to estimate detection probability and density for a subset of the observations with limited-radius point counts.
Extrinsic and Intrinsic Sources of Variation in Plasma Lipid Metabolites of Free-Living Western Sandpipers (Calidris Mauri)
Authors: Guglielmo Christopher G. , O'Hara Patrick D. , Williams Tony D. 
Published: September 2019

AbstractPlasma lipid metabolites may be useful indicators of mass changes in migratory birds. To test utility of plasma metabolites in field studies, we examined effects of several extrinsic (bleed time, time of day, location) and intrinsic (body mass, sex, age, migratory state) factors on plasma concentrations of triglycerides (TRIG), glycerol (GLYC), and B-OH-butyrate (BUTY) in free-living Western Sandpipers (Calidris mauri). TRIG and GLYC decreased rapidly following capture (2–20 min), whereas BUTY did not change. GLYC and BUTY were negatively correlated to body mass. TRIG was positively correlated to body mass in migrant females, but not consistently in migrant males, or in females captured on the wintering grounds. Taking into account other sources of variation, the two measures of lipid utilization (GLYC and BUTY) varied little through the year. TRIG showed the greatest potential for use in field studies. TRIG was lowest during winter, when birds were leanest, and highest during spring and fall migration, when sandpipers were gaining mass rapidly at stopovers. TRIG differed between sandpipers refuelling a two stopover sites separated by 35 km, demonstrating that populations of birds can have characteristic lipid metabolite profiles that may reflect local differences in fattening rate.
Offspring Desertion by Double-Brooded Female Barn Owls (Tyto Alba)
Authors: Roulin Alexandre 
Published: September 2019

Abstract
In double-brooded species, the sex that contributes less to breeding success may desert offspring before the end of the rearing period to start a new breeding attempt with another partner. I evaluated that prediction in the Barn Owl (Tyto alba), a species in which the male feeds the brood on average twice as often as the female. Among birds that produced a second brood, 46% of females and 4% of males deserted their offspring before completion of parental duties to remate with another partner at a distance of 1 to 10 km. Offspring desertion did not appear to incur a reproductive cost to the deserter, because deserting females at the first nest produced a similar number of offspring as nondeserting ones. In most cases, the new mate of deserting females had not been previously captured in the study area, and hence had probably not previously bred that season. Although the second clutch of deserting females was larger and produced two weeks earlier than that of nondeserting females, their nesting success did not differ.
Dendroplex (=Xiphorhynchus) Necopinus Zimmer 1934 (Dendrocolaptidae) is a Junior Synonym of Dendrornis Kienerii (=Xiphorhynchus Picus Kienerii) Des Murs 1855
Authors: Aleixo Alexandre , Whitney Bret M. 
Published: September 2019

Abstract
John T. Zimmer described Xiphorhynchus necopinus (Zimmer's Woodcreeper) as a sibling species of the more widespread Xiphorhynchus picus (Straight-billed Woodcreeper). Despite his initial suspicion that a preexisting name (kienerii) could be applied to the new species he described, Zimmer discarded that possibility without directly examining the type of X. p. kienerii housed at the Museum National D'Histoire Naturelle in Paris, France. We studied plumage and measured wing chord and tail lengths of the type specimen of X. p. kienerii, comparing it with series of specimens of X. necopinus and X. picus. We show that X. necopinus and the type of X. p. kienerii are morphologically and morphometrically indistinguishable, and thus necopinus is synonymized with kienerii, the name that has priority. Because Zimmer mistakenly applied the name kienerii to a western Amazonian population of X. picus, most specimens in museums identified as X. p. kienerii after Zimmer's review (Zimmer 1934) are likely to refer to X. p. peruvianus.
Falkland Island Sedge Wrens (Cistothorus Platensis) Imitate Rather Than Improvise Large Song Repertoires
Authors: Kroodsma Donald E. , Woods Robin W. , Goodwin Elijah A. 
Published: September 2019

AbstractAmong songbirds, does reduced fidelity to a breeding site lead to vocal improvisation? Data for Cistothorus wrens suggest it does, because North American Sedge Wrens (C. platensis) have low breeding-site fidelity and improvise their large song repertoires, but sedentary or site-faithful populations of this and other Cistothorus species in the Neotropics and North America all imitate. We attempted to falsify this hypothesis by studying extreme south-temperate zone populations of Sedge Wrens in the Falkland Islands. We banded and recorded males on Kidney Island and Carcass Island, and then compared song matching among males both within and between islands. Birds on those islands were highly site-faithful from one breeding season to the next. Song repertoires were large, up to 400 in one bird, and songs of birds within an island were more similar to each other than to songs on the other island, showing that these birds do imitate. These results further support the idea that site fidelity promotes imitation of neighbors, and continue to highlight the unique correlation between reduced site-fidelity and song improvisation in the North American Sedge Wren.