bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Supplemental Food on Parental-Care Strategies and Juvenile Survival of Northern Goshawks
Authors: Dewey Sarah R. , Kennedy Patricia L. 
Published: September 2019

Abstract
Using food supplementation, we tested whether food limits juvenile survival in a population of Northern Goshawks (Accipiter gentilis) in northeastern Utah. The influence of additional food on female nest attendance also was investigated because those strategies may influence predation mortality rates of juveniles. We provided supplemental food near 13 nests from close to hatching until close to independence during the 1996 and 1997 breeding seasons. Thirteen additional nests served as controls and received no supplemental food. We compared the following variables at treatment and control nests: (1) adult female mass, (2) nestling mass and size, (3) female nest attendance, and (4) juvenile survival. Following supplemental feeding, adult females from treatment nests were heavier than their control counterparts, and remained closer to the nest during the latter part of the nestling period and throughout the postfledging period. Nestlings from supplemented nests were significantly heavier than those from unsupplemented nests, but results for size measurements were equivocal. Survival rates for treatment nestlings were significantly higher than controls in 1997, but not in 1996. Those results support the hypothesis that food does not limit avian reproductive success on an annual basis. Most deaths in 1997 were the result of starvation or sibling competition. That observation, and the fact that fed nestlings were heavier, is consistent with the idea that treatment nestlings were in improved nutritional condition. Overall patterns of mass and nest-attendance for adult female goshawks supports the hypothesis that female condition and behavior are adjusted in response to food supplies. However, it is less clear what role the females' presence in the nest stand plays in mediating juvenile deaths, because we did not document predation as a primary mortality factor during the two years of this study. The apparent flexibility in female nest attendance behavior suggests that such plasticity may be an adaptation to lower the risk of predation.
Effects of Habitat Fragmentation on Pairing Success of Ovenbirds: Importance of Male Age and Floater Behavior
Authors: Bayne Erin M. , Hobson Keith A. 
Published: September 2019

AbstractBetween 1996 and 1998, we compared pairing success of territorial male Ovenbirds (Seiurus aurocapillus) in forest fragments created by forestry (n = 3) and agriculture (n = 10) to contiguous forest plots (n = 3) in the southern boreal mixedwood forest of central Saskatchewan. The percentage of Ovenbird males paired per site was lower in fragments created by agriculture (86 ± 3%) and forestry (87 ± 3%) than in contiguous forest (97 ± 3%). At the individual level, second-year males (82%) were less likely to be paired than after-second-year males (94%), whereas males closer to edges were less likely to be paired than those in forest interiors. Although pairing success differed among landscapes, those differences were smaller than reported in studies conducted in eastern North America. The high density of birds in our study area may have resulted in intense intraspecific competition, which could have prevented unpaired individuals from maintaining territories. Removal experiments in 1997 and 1998 demonstrated floaters occurred in contiguous forest, but rarely occurred in fragments created by agriculture. The presence of floaters in contiguous forest suggests the ratio of breeding to nonbreeding males in forest fragments and contiguous forest may be similar, but that the strategy (i.e. floater vs. territorial) used by unpaired birds may differ among landscapes.
Bird Migration Through a Mountain Pass Studied With High Resolution Radar, Ceilometers, and Census
Authors: Williams Timothy C. , Williams Janet M. , Williams Peter G. , Stokstad Paul 
Published: September 2019

AbstractAutumnal migration was studied with high-resolution radar, ceilometer, and daily census in the area of Franconia Notch, a major pass in the northern Appalachian Mountains. Under synoptic conditions favorable for migration, broadfront movements of migrants toward the south passed over the mountains, often above a temperature inversion. Birds at lower elevations appeared to be influenced by local topography. Birds moving southwest were concentrated along the face of the mountain range. Birds appeared to deviate their flights to follow local topography through the pass. Specific migratory behavior was not associated with species or species groups. Under synoptic conditions unfavorable for southward migration, multimodal movements probably associated with local flights were as dense as the southward migrations described above. Avian migrants reacting to local terrain may result in concentrations of migrants over ridge summits or other topographic features.
Lek-Like Mating System of the Monogamous Blue-Black Grassquit
Authors: Almeida Juliana B. , Macedo Regina H. 
Published: September 2019

AbstractIn this study, we investigated the role of display and mating system of the little known Neotropical Blue-black Grassquit (Volatinia jacarina). Males form aggregations and execute a highly conspicuous display, resembling traditional leks. Number of displaying males declined throughout the study period, though displaying intensity during the season showed no variation. Individual males had significantly different displaying rates and also defended territories of very different sizes, ranging from 13.0 to 72.5 m2, but we found no association between territory sizes and the average displaying rates of the resident males. There also is no association between displaying rates of males and size and vegetation structure of their territories. Four of seven nests were found within male territories and observations indicated that both sexes invest equally in caring for nestlings. Results suggest that the Blue-black Grassquit does not fit into the traditional lek mating system, contrary to what has been proposed in the scarce literature available. However, it is clear that these apparently monogamous birds behave like a lekking species. We speculate about the possibility that aggregation of nesting territories in this species may be due to sexual selection pressures, and suggest that the Blue-black Grassquit may be an ideal candidate to test Wagner's (1997) hidden-lek hypothesis.
Microclimate of Tree Cavity Nests: Is it Important for Reproductive Success in Northern Flickers?
Authors: Wiebe Karen L. 
Published: September 2019

AbstractI measured structural characteristics of 160 Northern Flicker (Colaptes auratus) nests at Riske Creek, British Columbia, and placed electronic data-loggers in a subsample of 86 nests to record internal temperatures after the flickers completed nesting. Using multiple regression, I found that the best predictors of a variety of nest-cavity temperature variables were tree health, diameter of the tree at cavity height, and orientation of the cavity. Small and dead trees showed the most extreme (maximum and minimum) temperatures during the day, but, on average, were the coldest nests from the perspective of incubation. South-facing cavities reached the highest temperatures during the day, and the orientation of natural cavities was also biased towards the south. I predicted that cold nests would be energetically expensive for adults and nestlings, and found that clutch size was positively correlated with mean cavity temperature. However, there did not appear to be any relationship among nest temperature and hatching or fledging success.
Timing of Breeding Range Occupancy Among High-latitude Passerine Migrants
Authors: Benson Anna-Marie , Winker Kevin 
Published: September 2019

AbstractThe brief subarctic summer limits the time available for birds to complete their reproductive activities, yet the temporal requirements of high-latitude passerine migrants are not well understood. Our analyses examined the timing of spring and autumn migration among 18 passerine species to obtain indirect estimates of the time they occupy their breeding ranges in northwestern North America. From 1992 to 1998, the Alaska Bird Observatory (64°50′N, 147°50′W) banded 31,698 individuals during the most intensive standardized mist-netting study ever conducted in subarctic North America. Among the migrants examined, the estimated number of days that species were present in interior Alaska ranged from 48 days for adult Alder Flycatchers (Empidonax alnorum) to 129 days for American Robins (Turdus migratorius). Adults departed significantly later in autumn than immatures in 10 of 18 species we examined and significantly earlier than immatures in only one species, Alder Flycatcher. Breeding range occupancy of Nearctic–Neotropic migrants occurs in this region within the range of average frost-free temperatures in Fairbanks, Alaska, and is significantly shorter in duration than among Nearctic–Nearctic (“short-distance”) migrants at this latitude.
Growth Rate and Energetics of Arabian Babbler (Turdoides squamiceps) Nestlings
Authors: Anava Avner , Kam Michael , Shkolnik Amiram , Degen A. Allan 
Published: September 2019

Abstract
Arabian Babblers (Turdoides squamiceps) are territorial, cooperative breeding passerines that inhabit extreme deserts and live in groups all year round. All members of the group feed nestlings in a single nest, and all group members provision at similar rates. Nestlings are altricial and fledge at about 12 to 14 days, which is short for a passerine of its body mass. Because parents and helpers feed nestlings, we hypothesized that the growth rate of nestlings is fast and that they fledge at a body mass similar to other passerine fledglings. Using a logistic growth curve, the growth rate constant (k) of nestlings was 0.450, which was 18% higher than that predicted for a passerine of its body mass. Asymptotic body mass of fledglings was 46 g, which was only 63% of adult body mass, a low percentage compared to other passerines. Energy intake retained as energy accumulated in tissue decreased with age in babbler nestlings and amounted to 0.29 of the total metabolizable energy intake over the nestling period. However, energy content per gram of body mass increased with age and averaged 4.48 kJ/g body mass. We concluded that our hypothesis was partially confirmed. Growth rate of babbler nestlings was relatively fast compared to other passerine species, but fledgling mass was relatively low.
Does Group Size Affect Field Metabolic Rate of Arabian Babbler (Turdoides squamiceps) Nestlings?
Authors: Anava Avner , Kam Michael , Shkolnik Amiram , Degen A. Allan 
Published: September 2019

Abstract
Arabian Babblers (Turdoides squamiceps) are territorial, cooperative breeding passerines in which groups consist of parents and helpers. All members of the group feed nestlings in a single nest and all group members provision at similar rates. We hypothesized that the field metabolic rate (FMR) of Arabian Babbler nestlings is related to group feeding; that is, FMR would be greater in nestlings of larger rather than smaller sized groups. To test that hypothesis, we measured FMR of 10 day old nestlings from small (2 and 3 individuals), medium (4 and 5 individuals), and large (6 or more individuals) groups. We also determined number of hatchlings and fledglings produced per group. There was an increase in body mass and FMR from small to medium-sized groups, but there was a levelling off or decrease in those parameters in large groups. That suggests that there is an optimum group number for provisioning nestlings, above which there may be a negative effect. The relationship between group size and annual number of eggs was not significant, but there was a positive and linear relationship between group size and annual fledglings production. Thus, more eggs reached the fledgling stage with an increase in group size, suggesting that larger groups are better able to defend the nest against predators.
Diving Depths of Northern Gannets: Acoustic Observations of Sula Bassana from an Autonomous Underwater Vehicle
Authors: Brierley Andrew S. , Fernandes Paul G. 
Published: September 2019

Abstract
The Autonomous Underwater Vehicle (AUV) Autosub-1 made observations of the sea surface with an upward-looking echosounder during fish surveys in the vicinity of Shetland and Orkney (North Sea) in July 1999. Echograms from the AUV contained vertical traces extending downwards from the sea surface that were caused by diving seabirds. Visual observations provided evidence that those seabirds were Northern Gannets Sula bassana. Analysis of trace extent suggests a mean dive depth of 19.7 m (n = 19, SD = 7.5). Data on gannet diving depths are sparse, but this value is somewhat deeper than that accepted for the related Cape Gannet (Morus capensis, mean 5.9 m) which has been used in foraging models for the Northern Gannet. These observations have implications for our understanding of the foraging capabilities of gannets, and the interactions of gannets with commercially targeted fish species.
Latitudinal Variation in Female Local Return Rate in the Philopatric Pied Flycatcher (Ficedula hypoleuca)
Authors: Sanz Juan José 
Published: September 2019

AbstractPhilopatry and dispersal distances of female Pied Flycatcher (Ficedula hypoleuca) are presented for European populations using data from 25 breeding areas from 40 to 70°N. Female annual survival probabilities according to capture–recapture models were similar in two study areas in central Spain (45 and 52%). The present study shows that survival is underestimated by using annual local return rate in one of the two breeding populations under study in central Spain. In southern and central Europe, females were found to return equally regularly to their breeding areas, whereas in northern Europe (latitude >60°N) females returned at lower rates. I did not find that median dispersal distance varied among sites, nor was breeding distance related to locate survival rate. Therefore, the present study suggests that the decline in between-year local return rate of female Pied Flycatchers with increasing latitude over Europe may be more probably caused by differences in mortality than by geographical differences in site fidelity.
Body-mass Changes in Female Collared Flycatchers: State-dependent Strategy
Authors: Cichoń Mariusz 
Published: September 2019

Abstract
Collared Flycatcher (Ficedula albicollis) females experimentally were forced to prolong their incubation to address the question whether mass constancy during incubation and subsequent mass loss after hatching is actually related to breeding stage. Compared to unmanipulated control females a week after expected hatching, experimental females did not show any significant mass loss during prolonged incubation, whereas control females that successfully hatched their eggs dropped their mass significantly. Results show that body mass in females is associated with the reproductive stage and may reflect an adaptive strategy. High and stable incubation mass can be a fasting endurance in case of adverse weather conditions when females stay on the nest instead of foraging.
A Cytochrome-b Perspective on Passerina Bunting Relationships
Authors: Klicka John , Fry Adam J. , Zink Robert M. , Thompson Christopher W. 
Published: September 2019

Abstract
We sequenced the complete mitochondrial cytochrome-b gene (1,143 nucleotides) for representatives of each species in the cardinalid genera Passerina (6 species), Guiraca (1 species), and Cyanocompsa (3 species), and used a variety of phylogenetic methods to address relationships within and among genera. We determined that Passerina, as presently recognized, is paraphyletic. Lazuli Bunting (P. amoena) is sister to the much larger Blue Grosbeak (Guiraca caerulea). Indigo Bunting (P. cyanea) and Lazuli Bunting are not sister taxa as generally thought. In all weighted parsimony trees and for the gamma-corrected HKY tree, Indigo Bunting is the sister of two sister groups, a “blue” (Lazuli Bunting and Blue Grosbeak) and a “painted” (Rosita's Bunting [P. rositae], Orange-breasted Bunting [P. leclancherii], Varied Bunting [P. versicolor], and Painted Bunting [P. ciris]) clade. The latter two species form a highly supported sister pair of relatively more recent origin. Uncorrected (p) distances for ingroup (Passerina and Guiraca) taxa range from 3.0% (P. versicolor–P. ciris) to 7.6% (P. cyanea–P. leclancherii) and average 6.5% overall. Assuming a molecular clock, a bunting “radiation” between 4.1 and 7.3 Mya yielded four lineages. This timing is consistent with fossil evidence and coincides with a late-Miocene cooling during which a variety of western grassland habitats evolved. A reduction in size at that time may have allowed buntings to exploit that new food resource (grass seeds). We speculate that the Blue Grosbeak subsequently gained large size and widespread distribution as a result of ecological character displacement.
Age and Reproduction in Lesser Spotted Woodpeckers (Dendrocopos Minor)
Authors: Wiktander Ulf , Olsson Ola , Nilsson Sven G. 
Published: September 2019

AbstractWe examined the influence of female age, male age, and pair-bond duration on start of egg-laying, clutch size, and number of young fledged in the Lesser Spotted Woodpecker (Dendrocopos minor). We also attempted to disentangle the relative influence of individual age and pair-bond duration on reproduction, because the effect of those factors may be confounded. Breeding performance improved with age in that old females started egg-laying earlier and old males raised more young than yearlings, and old pairs both started egg-laying earlier and raised more young than new pairs. Clutch size was not affected by age, but showed a strong negative relation with laying date. Late-laying yearling females experienced a lower survival, and the survival of yearling males showed a positive relation with fledgling production. That differential survival was a likely mechanism explaining the differences in reproductive performance between yearling and old birds. Several analyses suggested that pair-bond duration had independent positive effects on reproduction. Benefit of long-term pair-bonds appeared to depend upon repeated breeding with a particular partner. The mechanisms behind the benefit of remating with a particular partner remain unclear, however. We postulate that much of the patterns of age effects on reproduction in the Lesser Spotted Woodpecker may be caused by constraints posed by the territorial system and effects of territory quality, although effects of individual quality can not be excluded.
Comparative Fuel use of Migrating Passerines: Effects of Fat Stores, Migration Distance, and Diet
Authors: Gannes Leonard Z. 
Published: September 2019

AbstractLipids are the dominant fuel source during migratory flight, but the factors controlling the relative importance of lipid, protein, and carbohydrate to flight metabolism remain unclear. I tested the nonexclusive hypotheses that diet, migration distance, or endogenous lipid reserves mediate variation in the fuels birds catabolize during migration. Blood plasma metabolite concentrations were significantly different among species, and indicated clear differences in protein and lipid utilization among three turdid chat and five sylviid warbler species caught during spring migration in the Negev Desert, Israel. Fruit-eating species (omnivores) catabolized less protein and more lipid during migration than insectivores. Metabolite concentrations of omnivorous Blackcaps (Sylvia atricapilla), Garden Warblers (S. borin), and Lesser Whitethroats (S. curruca) were consistent with low rates of proteolysis (low uric acid), and high rates of lipolysis (high free-fatty acid and β-hydroxybutyrate). On the other hand, metabolite concentrations of insectivorous Redstarts (Phoenicurus phoenicurus), Nightingales (Luscinia megarhynchos), Thrush Nightingales (L. luscinia), Barred Warblers (S. nisoria), and Orphean Warblers (S. hortensis) indicated increased proteolysis and decreased lipolysis. Blood metabolite concentrations, however, were not correlated with migration distance, and the results do not support the hypothesis that long-distance migrants use fuel differently than short-distance migrants. Triacylglycerol mobilization was positively correlated with the amount of visible subcutaneous fat, but blood metabolite composition was more strongly affected by diet. Omnivores and insectivores exhibit different fuel-use strategies to overcome the physiological challenges of migration.
Composition of Eggs and Neonates of Canada Geese and Lesser Snow Geese
Authors: Badzinski Shannon S. , Ankney C. Davison , Leafloor James O. , Abraham Kenneth F. 
Published: September 2019

AbstractWe collected eggs, neonates, and adults of Canada Geese (Branta canadensis interior) and Lesser Snow Geese (Chen caerulescens caerulescens) from Akimiski Island, Nunavut, during the 1996 breeding season. This was done to assess interspecific differences in egg composition, egg-nutrient catabolism, developmental maturity, tissue maturity, and body reserves, and to relate observed differences in those variables to ecological conditions historically experienced by Canada Geese and Lesser Snow Geese. Eggs of both species had identical proportional compositions, but Canada Goose embryos catabolized 13% more of their egg protein, whereas Lesser Snow Goose embryos catabolized 9% more of their egg lipid. Neonate Canada Geese and Lesser Snow Geese had similar protein reserves, relative to body size, but Lesser Snow Geese had relatively smaller lipid reserves than did Canada Geese. Relative to conspecific adults, Lesser Snow Goose goslings generally were structurally larger at hatch than were Canada Goose goslings. Neonate Lesser Snow Geese had more developmentally mature keels, wings, and breast muscles, and larger gizzards and caeca for their body size, than did neonate Canada Geese. Despite hatching from smaller eggs and having a shorter period of embryonic growth, skeletal muscles and gizzard tissues of Lesser Snow Geese were more functionally mature than those of Canada Geese. Increased lipid use during embryonic development could account for how Lesser Snow Geese hatched in a more developmentally and functionally mature state. In turn, differences in developmental and functional maturity of Lesser Snow Geese, as compared to Canada Geese, likely are adaptations that offset metabolic costs associated with their small body size, or to selection pressures associated with high arctic environmental conditions and colonial nesting and brood rearing.