bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breeding and Post-Breeding Habitat Use by Forest Migrant Songbirds in the Missouri Ozarks
Authors: Pagen Rich W. , Thompson III Frank R. , Burhans Dirk E. 
Published: September 2019

Abstract
We compared habitat use by forest migrant songbirds during the breeding and post-breeding periods in four Missouri Ozark habitats: mature upland forest, mature riparian forest, 9- to 10-year-old upland forest, and 3- to 4-year-old upland forest created by clearcutting. Adult forest-ground species showed a decrease in abundance in all habitats during the post-breeding period, but hatching-year birds of one of the two forest-ground species were most abundant in early-successional forest during this time. Adults of the two forest-canopy species tended to increase in abundance in 3- to 4-year-old forest from breeding season to post-breeding season. During the breeding season, some forest species were detected with mist-nets in the two early-successional habitats, but infrequently or not at all with point counts in those habitats. Forest birds captured in early-successional habitats during the breeding season may have been nonbreeding floaters, or may have been foraging there from nearby territories in mature forest. Dense shrubs or young trees in early-successional forest may provide habitat for nonbreeding and post-breeding forest migrant songbirds in the Missouri Ozarks.
Breeding Bird Abundance in Bottomland Hardwood Forests: Habitat, Edge, and Patch Size Effects
Authors: Sallabanks Rex , Walters Jeffrey R. , Collazo Jaime A. 
Published: September 2019

AbstractWe studied breeding bird communities in extensive bottomland hardwood forests along the lower Roanoke River in North Carolina during 1992 and 1993. We documented a rich avian community and recorded exceptionally high densities of two species (Prothonotary Warbler Protonotaria citrea, Acadian Flycatcher Empidonax virescens), as well as modest densities of three species rarely encountered elsewhere in the region (Cerulean Warbler Dendroica cerulea, Swainson's Warbler Limnothlypis swainsonii, American Redstart Setophaga ruticilla). The effects of patch size and edge on bird abundance were small in this forested landscape, but forest type had a large effect. We found half of the species analyzed to differ in abundance between the two primary habitat types, swamp forest and levee forest. In contrast, no species was consistently more abundant at patch interiors than near edges, and only two forest birds were more common in large compared with small patches. Species analyzed included permanent residents, short-distance migrants, Neotropical migrants, and those identified as forest-interior and area-sensitive species in other studies. Our results suggest that the Roanoke River bottomland forests may be functioning effectively as a reserve for a number of bird species.
Pair Formation and Copulation Behavior in Least Flycatcher Clusters
Authors: Tarof Scott A. , Ratcliffe Laurene M. 
Published: September 2019

AbstractLeast Flycatcher Empidonax minimus pairs form dense clusters of territories on the breeding grounds. We describe pair formation and copulation behavior (both within- and extra-pair) in Least Flycatcher clusters. Pair formation involved a complex behavioral sequence of trill vocalizations and visual display. Within-pair copulations were five times more likely to achieve cloacal contact than were extra-pair copulations. Least Flycatchers exhibited an overall within-pair mating effort of 2.0 ± 0.5 events pair−1 hr−1 compared to an extra-pair mating effort of 1.8 ± 0.3 events pair−1 hr−1. Within- and extra-pair mating behavior by focal birds were distinctly different with respect to rate, conspicuousness, duration, aggression intensity, and pre-copulatory display. The rate of territory incursions for extra-pair copulations was high. We discuss copulation behavior in the context of male and female mating tactics, and highlight the disparity in our knowledge of mating behavior in other members of this genus.
Artificial Nest Predation and Abundance of Birds Along an Urban Gradient
Authors: Jokimäki Jukka , Huhta Esa 
Published: September 2019

Abstract
We studied nest predation pressure on birds along an urban gradient in urban parks in three Finnish towns. Artificial ground nests with Japanese Quail (Coturnix coturnix japonicus) eggs were depredated more in the urban area than in the adjacent forest area. Within each town, the nest predation rate was higher in the town center than in the less urbanized area of detached houses. Predation rates did not vary from year to year or between study towns. Abundances of generalist avian predators were higher in the town center than in the area of detached houses and in the surrounding forest area. Most of the nests in the town center were destroyed by avian predators. Predation rate of artificial nests in each of the town areas was higher in managed parks than in unmanaged parks, presumably due to the less dense vegetation in the managed than the unmanaged parks. A test involving covering nests revealed that artificial nests covered by adjacent vegetation survived better than nests with less cover. In our study, artificial nest loss reflected the distribution of avian nest predators. Ground nesters were present at lower abundances in areas where concealing vegetation was missing and avian nest predation was high. Apparently, nest predation is one of the several possible mechanism affecting urban bird assemblages.
Do Band-Tailed Pigeons Seek a Calcium Supplement at Mineral Sites?
Authors: Sanders Todd A. , Jarvis Robert L. 
Published: September 2019

AbstractWe tested the hypotheses that mineral sites in western Oregon are used by Band-tailed Pigeons (Columba fasciata) to supplement dietary calcium and sodium. We compared mineral composition of sites used by Band-tailed Pigeons, adjacent unused sites, and three major food items during the nesting season. Sixty-five percent of used mineral sites were low in calcium (<200 ppm), whereas mean concentrations in food items were high (1,960–2,290 ppm). All but one used mineral site were high in sodium (≥678 ppm), whereas mean concentrations in food items were low (20–254 ppm). Food items were high in mean concentrations of potassium (12,470–26,980 ppm) and potassium:sodium ratios (138–656). Used and adjacent, unused, estuary mineral sites were similar in calcium and sodium concentrations. We hypothesize that because of insufficient sodium intake and inefficient sodium retention, Band-tailed Pigeons seek a sodium source to supplement their diet during the nesting season. Use of mineral sites probably depends upon sodium concentration, but also vegetation structure, development, human activity, and congregation use by Band-tailed Pigeons. Used mineral sites appear to be scarce in western Oregon, and are seemingly essential resources for this species. Eighty-six percent of known currently-used mineral sites are privately owned and subject to possible alteration from land-use practices. Mineral sites used by Band-tailed Pigeons should be included in the overall management scheme for maintaining stable breeding populations of this species.
A Molecular Phylogeny of the Dove Genus Zenaida: Mitochondrial and Nuclear DNA Sequences
Authors: Johnson Kevin P. , Clayton Dale H. 
Published: September 2019

AbstractWe reconstructed a phylogeny for the seven species of doves in the genus Zenaida on the basis of a combined analysis of mitochondrial (ND2 and cytochrome b) and nuclear (fibrinogen intron 7) DNA sequences. This phylogeny, which is completely resolved, is well supported with all nodes showing greater than 50% bootstrap support. There was no significant conflict between trees based on each gene independently, although trees produced from fibrinogen intron 7 did not resolve relationships among five of the Zenaida species. The species status of Z. graysoni, as well as that of Z. meloda, is suggested based on their divergence from sister taxa (about 1% and 4%, respectively) and other differences. Zenaida can be divided into two major groups: Zenaida asiatica and Z. meloda versus Z. aurita, Z. galapagoensis, Z. auriculata, Z. graysoni, and Z. macroura.
Species Limits and Recent Population History in the Curve-Billed Thrasher
Authors: Zink Robert M. , Blackwell-Rago Rachelle C. 
Published: September 2019

AbstractWe surveyed 1,115 base pairs of mitochondrial DNA sequence from three gene regions in 66 Curve-billed Thrashers (Toxostoma curvirostre) taken from throughout their range. We found that populations sorted unambiguously into three groups. Two of these groups, the Curvirostre and Palmeri groups, have been known for many years because of their distinctive phenotypic characteristics, and their status was recently confirmed with an intensive morphometric analysis. The third (southern) group consists of populations in Puebla and Oaxaca, Mexico. The strong morphological and mtDNA distinctiveness of the Curvirostre and Palmeri groups suggests that they warrant species status. We recommend that more specimens of the southern group be obtained prior to formal taxonomic recognition of this form. Coalescence analyses suggest that the Curvirostre group has undergone a recent population increase, whereas the Palmeri group seems to have been more stable in its Sonoran Desert range.
Pacific Coast and Southwest Interior Populations of the Hutton's Vireo Differ in Basic Song Parameters
Authors: Baril Colette T. , Barlow Jon C. 
Published: September 2019

Abstract
Comparisons of song parameters, including syllable length and maximum and minimum frequency, from six populations of the Hutton's Vireo (Vireo huttoni) show differences in syllable length and minimum frequency measurements. Specifically, syllables produced by Pacific coastal birds tend to be shorter than those from southwest interior populations, although these differences are not statistically significant at the pairwise-comparison level. Syllables produced by most coastal populations have significantly higher mean minimum frequencies when compared with those from interior populations. Differences between songs of coastal and interior populations are consistent with genetic differences that separate the two groups. Differences in song may be attributed to the acoustical properties of coastal versus interior habitats.
Roost Site Selection of Great Horned Owls in Relation to Black Fly Activity: An Anti-Parasite Behavior?
Authors: Rohner Christoph , Krebs Charles J. , Hunter D. Bruce , Currie Douglas C. 
Published: September 2019

AbstractWe document a shift in roosting behavior of Great Horned Owls (Bubo virginianus) from winter and late spring to summer. During summer, Great Horned Owls roosted near the ground or exposed on open ground, whereas they chose concealed perches at mid-canopy level for the rest of the year as typical for forest owls. This shift of roosting behavior coincided with the emergence of ornithophilic black flies, which transmit avian malaria (Leucocytozoon spp.). The shift in roosting behavior was consistent with measurements of parasite exposure at different habitat positions. Black fly activity was highest at mid-canopy level, and almost no black flies were active on open ground. Ground-roosting was not caused by poorly developed flying capability of juveniles, because solitarily-roosting adult owls showed the same behavioral shift in a second year of study. Black flies and avian malaria are widely distributed, and the effect of the vertical distribution of these parasites in forests on roosting, nesting, and foraging of sylvatic birds deserves further study.
Observations of the Pale-Eyed Blackbird in Southeastern Peru
Authors: Orians Gordon H. , Orians Elizabeth N. 
Published: September 2019

Abstract
We report the first known nest of the Pale-eyed Blackbird (Agelaius xanthophthalmus) and describe the behavior of breeding and nonbreeding pairs at Cocha Cashu, Manu National Park, Peru. Birds traveled as pairs within limited areas, whether or not they were breeding. During incubation, which is performed only by the female, the male typically remains near the nest and the birds are in regular vocal contact by means of frequent duets. Its monogamous social system is similar to that of other marsh-nesting species in its clade.
Contrasting Brood Sizes in Common and Arctic Terns: The Roles of Food Provisioning Rates and Parental Brooding
Authors: Robinson James A. , Hamer Keith C. , Chivers Lorraine S. 
Published: September 2019

AbstractArctic Terns (Sterna paradisaea) and Common Terns (S. hirundo) are similar in many aspects of their breeding ecology, but Common Terns generally lay three eggs per clutch whereas Arctic Terns lay two. In our study, Common Terns had a higher rate of food delivery and energy supply to the nest and higher nest attendance, indicating that they made trips of shorter average duration. This suggests that the number of chicks raised by these two species was primarily limited by the rate at which parents could supply food. However, estimated daily metabolizable energy intake of chicks was about 30% higher in Common Terns than in Arctic Terns. Common Tern chicks apparently spent a higher proportion of daily energy intake on maintenance of body temperature. It remains unknown whether this difference was because Common Tern parents could not brood three chicks as effectively as Arctic Terns brooded two or because the energy requirements for heat production in the third-hatched Common Tern chick were particularly high. If brooding did play a less important role in the energy budgets of Common Terns, the number of chicks that Arctic Terns could raise may have been limited not only by the rate at which parents could supply food to the nest but also by the requirements of chicks for brooding. We suggest that more detailed studies on the role of brooding constraints in limiting brood size in these species are required to clarify this matter.
Post-Fledging Dispersal of Burrowing Owls in Southwestern Idaho: Characterization of Movements and use of Satellite Burrows
Authors: Andrew King R. , Belthoff James R. 
Published: September 2019

AbstractUsing radiotelemetry, we monitored dispersing juvenile Western Burrowing Owls (Athene cunicularia hypugaea) within a migratory population in southwestern Idaho during 1994 and 1995. Owls remained within natal areas for an average (± SE) of 58 ± 3.4 days post-hatching before moving permanently beyond 300 m, which was our operational cutoff for dispersal from the natal area. On average, owls dispersed on 27 July (range: 15 July to 22 August), which was approximately 4 weeks after fledging. After initiating dispersal, juveniles continued moving farther away from their natal burrows and, by 61–65 days post-hatching, they had moved 0.6 ± 0.2 km. Each juvenile used 5.1 ± 1.2 satellite burrows, and individual satellite burrows were used for up to 14 days. The average date on which we last sighted radio-tagged juveniles was 13 August, and all but one juvenile departed the study area by early September. Our study illustrates the importance of satellite burrows to dispersing Burrowing Owls.
Effects of Brown-Headed Cowbirds on the Nesting Success of Chipping Sparrows in Southwest Colorado
Authors: Ortega Catherine P. , Ortega Joseph C. 
Published: September 2019

AbstractWe documented effects of Brown-headed Cowbird (Molothrus ater) parasitism on Chipping Sparrows (Spizella passerina) in southwest Colorado. Overall, 17 of 77 nests (22%) were parasitized. Abandonment was significantly higher among parasitized nests (29%) than unparasitized nests (5%). More Chipping Sparrows hatched and fledged per unparasitized nest than per parasitized nest. Reduction of host hatching and fledging rates in parasitized nests was attributable to smaller clutch size and higher abandonment. The major source of nest failure was predation, not parasitism; overall, 53% failed from predation, and only 6% failed from parasitism. There were no differences in weight, ulna length, tarsometatarsus length, or length of outermost primary between sparrow nestlings in parasitized and unparasitized nests. Only 18% of cowbird eggs laid resulted in a fledged cowbird. We observed no differences in nest placement or nest concealment between unparasitized and parasitized nests.
Daily Energy Expenditure of Nestling Bald Eagles in Northern Wisconsin
Authors: Dykstra Cheryl R. , Karasov William H. , Meyer Michael W. , Warnke D. Keith 
Published: September 2019

Abstract
We measured field metabolic rate of nestling Bald Eagles (Haliaeetus leucocephalus) in northern Wisconsin, using doubly-labeled water. In inland northern Wisconsin and along the Wisconsin Lake Superior shore, eaglets aged 39–60 days, weighing 3.08–4.85 kg, expended an average of 2,427 ± 100 kJ day−1. Nestling field metabolic rate was weakly correlated with nestling age, but not with mass. Field metabolic rate of eaglets can be used to estimate the biomass of food that adult eagles must provide from their environment, a datum that is important for determination of habitat suitability.
Accipiter Predation of American Redstart Nestlings
Authors: McCallum Cynthia A. , Hannon Susan J. 
Published: September 2019

Abstract
We used small video cameras to film predators at nests of American Redstarts (Setophaga ruticilla). We filmed three predation events, all by accipitrine hawks, in which no signs of predation were left at nests. Hence, as suggested by other workers, predator identification based on signs left at nests is unreliable. In addition, predation rates may be underestimated if accipiters or other predators take nestlings just prior to fledging without leaving signs. These incidents may be interpreted by field workers as nests where young fledged successfully.
Importance of the Supratidal Habitats for Maintaining Overwintering Shorebird Populations: How Redshanks Use Tidal Mudflats and Adjacent Saltworks in Southern Europe
Authors: Masero José A. , Pérez-Hurtado Alejandro 
Published: September 2019

Abstract
The prey-size selection, foraging behavior, and intake rate of overwintering Redshanks (Tringa totanus) were studied in a supratidal-intertidal system with high intertidal densities of shorebirds (100 birds ha−1). For assessing the importance of the energy obtained in the supratidal habitat (saltworks), daily consumption in this habitat was compared with the total daily energy requirement. Redshanks passively select prey within a certain size range from those accessible on the intertidal area. Despite the high prey biomass on the mudflats, Redshanks exhibited a low intake rate during winter (0.321 kJ min−1). This low intake seems to be related to the influence of the high densities of foraging shorebirds on the behavior of prey. Although intake rate was higher in the saltworks, the majority of Redshanks did not choose to feed there in winter. This foraging pattern seems to be related to density-dependent effects in habitat occupancy, as social interactions could have kept Redshanks out of the saltworks in winter according to the predictions of the ideal-despotic model. Energy intake in the supratidal habitat contributed 23% and 82% of the total daily energy requirement in winter and the pre-migration period, respectively. Redshanks were able to meet the total daily energy requirement during the pre-migration period by increasing foraging time in the saltworks. The availability of supratidal foraging habitats seems to contribute significantly to the maintenance of the population of overwintering Redshanks.
Nonbreeding Habitat Selection and Foraging Behavior of the Black-Throated Green Warbler Complex in Southeastern Mexico
Authors: Greenberg Russell , Gonzales Claudia Elia , Bichier Peter , Reitsma Robert 
Published: September 2019

Abstract
We studied the ecological distribution and foraging behavior of three species in the Black-throated Green Warbler (Dendroica virens) species group in the Eastern Highlands of Chiapas, Mexico. The three species, Black-throated Green, Hermit (D. occidentalis) and Townsend's (D. townsendi) Warblers are largely allopatric on the breeding grounds and variably sympatric during the winter. We surveyed the composition of 166 mixed-species flocks and recorded habitat variables associated with the flock location along an elevational transect. We found that Black-throated Green and Townsend's Warblers segregated by altitude, whereas Hermit Warbler overlapped extensively with both other species. Even though Townsend's and Hermit Warblers co-occurred commonly in the same flocks, the latter showed strong selective use of pine trees and the former showed weaker selectivity of oak trees. Black-throated Green Warbler showed no tree-type selection. The combined differences in elevational distribution and tree-type use resulted in very low ecological overlap for the three species. The Black-throated Green Warbler was the most distinct in its foraging behavior, occurring more often in the outer and upper branches of trees, and using hanging, aerial, and hovering maneuvers more than its congeners. In addition, it showed a higher movement frequency and a lower rate of between-branch flights. The Black-throated Green Warbler also is the most morphologically distinct as a result of its overall smaller body size, which is consistent for the trend towards larger body size in more conifer-specialized species in this genus. We propose that as new breeding populations were founded, and speciation occurred, individuals of the more derived species occupied decreasingly productive winter habitats.
Foraging Success and Foraging Habitat Use by Cattle Egrets and Little Egrets in the Camargue, France
Authors: Lombardini Katia , Bennetts Robert E. , Tourenq Christophe 
Published: September 2019

Abstract
We examined habitat use by Little Egrets (Egretta garzetta) and Cattle Egrets (Bubulcus ibis) that nest together in mixed-species colonies in the Camargue of southern France. We explored the relative use of seven habitat types in relation to their availability and tested the hypothesis that selection of habitat types was related to foraging success, with the prediction that increased foraging success in a given habitat corresponded with increased use of that habitat type. Ricefields and other agricultural habitats were used more than expected by Cattle Egrets, an invasive species in southern Europe; whereas Little Egrets, which are native to the Camargue, tended to select natural freshwater marshes and lagoons. Results were consistent with the hypothesis that increasing use of habitats corresponded with higher foraging success for both species. However, when this analysis was restricted to habitats with sufficient numbers of birds to enable estimates of biomass intake, the association was no longer apparent for Little Egrets.