bluuebunny/crossref_metadata_2025 huggingface dataset:
Survival, Habitat Use, and Movements of Fledgling White-Throated Robins (Turdus Assimilis) in a Costa Rican Agricultural Landscape
Authors: Cohen Emily B. , Lindell Catherine A.
Published: September 2019

We used radiotelemetry to study behavior of White-throated Robins (Turdus assimilis) during the postfledging dependent period. The study was conducted in a mixed agricultural and forested landscape in southern Costa Rica from March through August of 2001 and 2002. A transmitter was attached to one fledgling per brood (n = 53). Each bird was located daily prior to dispersal. We compared survivorship, habitat use, and movements of fledglings from (1) nests in coffee plantations and (2) nests in cattle pastures. The probability of surviving the first three weeks out of the nest was 0.67 ± 0.07 (SE) for fledglings from nests in all habitats, 0.58 ± 0.10 for fledglings from nests in coffee, and 0.74 ± 0.26 for fledglings from nests in pasture. Fledglings from nests in pasture left their nesting habitat at younger ages than did those from nests in coffee, and most birds from both habitats moved into forest when they left their nesting habitat. Pasture was rarely used during the postfledging period, whereas coffee plantations were used extensively. Fledglings that remained in agricultural habitats (coffee or pasture) were less likely to survive until dispersal than were those that moved into forested areas. Average daily distances from the nest gradually increased until fledglings dispersed away from the natal area, always into forest, and were not different for birds from pasture or coffee. White-throated Robins can nest successfully in agricultural habitats, but use of forest positively influenced survivorship of young during the postfledging dependent period.
Proximate Factors Determining Age and Mass at Fledging in Rhinoceros Auklets (Cerorhinca Monocerata): Intra- and Interyear Variations
Authors: Deguchi Tomohiro , Takahashi Akinori , Watanuki Yutaka
Published: September 2019

In alcids, growth rate and hatching date of chicks appear to affect fledging age and mass. Underlying mechanisms are hypothesized to be (1) critical wing length at fledging for postfledging survival, (2) synchronization of fledging to dilute predation risk, and (3) variable parental provisioning according to timing of breeding. To elucidate the effects of growth rate and hatching date on fledging age and mass, and to test those mechanistic hypotheses, we measured chick growth and fledging periods in Rhinoceros Auklets (Cerorhinca monocerata) at Teuri Island from 1995 to 2000. The multiple-linear regression analysis showed that intrayear variations of fledging age and mass were explained by growth rate or hatching date in five out of six years. Faster-growing chicks fledged younger and heavier, and earlier-hatched chicks fledged older and heavier. Consequently, no apparent correlation between fledging age and mass was observed in five out of six years. Analysis of interyear variation showed a negative correlation between fledging age and mass, which indicates that growth rates rather than hatching dates had a major effect. Wing length at fledging was independent of growth in mass. More than 80% of chicks fledged when they attained a narrow range of wing length (130–150 mm), presumably because they remained in their nests until they attained the critical wing length. In five out of six years, the chicks did not synchronize timing of fledging relative to timing of hatching. Later-hatched chicks attained lighter peak masses and at younger ages, which may indicate that their parents decreased provisioning rates when the chicks were still young. We suggest that (1) critical wing length at fledging and (2) variable parental provisioning according to timing of breeding could be underlying mechanisms determining these relationships between fledging age and mass.
Discrimination of Individual Voices in Male Great Bitterns (Botaurus Stellaris) in Italy
Authors: Puglisi Luca , Adamo Claudia
Published: September 2019

Recorded vocalizations from 18 known Great Bitterns (Botaurus stellaris) were analyzed, both quantitatively and qualitatively, to determine the amount of intra- and inter-individual variation. All parameters examined showed significant variation among males, and vocalizations of the same male were not stable over time. Variability within males over time makes re-identification of individuals on the basis of vocalizations difficult. The high degree of uncertainty in recognizing individuals limits the usefulness of vocalizations for censusing of bitterns.
Sap-Feeding Behavior and Tree Selection in the Endangered Akiapolaau (Hemignathus Munroi) in Hawaii
Authors: Pejchar Liba , Jeffrey Jack
Published: September 2019

The Akiapolaau (Hemignathus munroi), an endangered Hawaiian honeycreeper, drills 3–5 mm deep holes in particular ohia trees (Metrosideros polymorpha) and drinks the sap that emerges, a remarkable example of convergent evolution in sap-feeding behavior with mainland woodpeckers and Australian sugar-gliders. There has been little research on how this species selects sap trees (“Aki trees”) and what advantages they confer. We marked the locations of and collected sap samples and microhabitat data from 101 Aki trees and 73 randomly selected control trees in Hakalau Forest National Wildlife Refuge, Hawaii. Aki trees were rare (2 ha−1), spatially clustered, and defended by Akiapolaau. Sap flow volume and speed were substantially greater in Aki trees than in controls. Aki trees also were larger, had thinner bark, and were more likely to be located on convex east-facing slopes where more light is available. Those results support the hypothesis that Aki trees are selected on the basis of high sap flow and a suite of unique microhabitat and tree characteristics. Sap may be an important energy source in times of low insect availability and a potent alternative to nectar for the Akiapolaau. Aki trees are both a fascinating example of niche specialization and a factor that should be considered when conserving or restoring habitat for this endangered species.
Systematics and Biogeography of Double-Collared Sunbirds From the Eastern Arc Mountains, Tanzania
Authors: Bowie Rauri C. K. , Fjeldså Jon , Hackett Shannon J. , Crowe Timothy M.
Published: September 2019

The double-collared sunbirds of the Eastern Arc Mountains of Tanzania and southeastern Kenya are characterized by regional variation in morphology and plumage. That variation has resulted in considerable dispute over their taxonomic status and delineation of range boundaries. It has been suggested that Moreau's Sunbird (Nectarinia Moreaui) is an atypical phenotype that has arisen from a hybridization event between the more widely distributed Eastern Double-collared Sunbird (N. mediocris) and the narrowly distributed Loveridge's Sunbird (N. loveridgei). A discriminant analysis of six standard morphological characters indicates that Moreau's Sunbird is intermediate in shape and size between the Eastern Double-collared and Loveridge's sunbirds. There is greater overlap between female Moreau's and Eastern Double-collared sunbirds than between males; Loveridge's Sunbird shows little overlap with the other taxa. Discrete plumage characters separate all three taxa. Molecular analyses of 728 base pairs of mitochondrial DNA (NADH3 and control region) suggest that Moreau's Sunbird is a valid taxon and the sister species to Loveridge's Sunbird. Eastern Double-collared Sunbird haplotypes can be divided into three distinct clades, separated from each other by substantial genetic divergence (approximately 8–10% sequence divergence). We propose species status for each of those clades and suggest the following three taxa: N. mediocris Shelley 1855, N. usambarica Gröte 1922, and N. fuelleborni Reichenow 1899. Finally, we propose a biogeographical hypothesis of speciation events within the N. mediocris species complex.
Vicariant Speciation of Curassows (Aves, Cracidae): A Hypothesis Based on Mitochondrial DNA Phylogeny
Authors: Pereira Sérgio Luiz , Baker Allan J.
Published: September 2019

The curassows comprise 14 species of sedentary Neotropical birds classified in four genera (Crax, Nothocrax, Mitu, and Pauxi) in the family Cracidae. Congeneric species have a striking pattern of allopatric distributions that might be attributable to vicariance, dispersal, or a combination of the two. To test those biogeographic hypotheses, a strongly supported phylogeny was needed, so that existing problems of taxonomic rank could be solved and a better understanding of the group's evolutionary history attained. We therefore estimated the phylogenetic relationships of all 14 species, on the basis of 6,929 sites of six different mitochondrial DNA regions, and reassessed the status of the four genera. Sequences from the ND4 gene favored a tree that was highly incongruent with the tree recovered using the other five gene regions. However, when the ND4 sequences were concatenated with the sequences of the other genes, the optimal phylogeny was unchanged from that derived for the other genes. That combined tree was divided into two well-supported clades: one containing the seven species of Crax and the other containing the monospecific genus Nothocrax, as sister to a clade of the Mitu and Pauxi species. Mitu and Pauxi are not reciprocally monophyletic, which appears to be attributable to a distant hybridization event and a transfer of Mitu mtDNA into P. unicornis. We estimated divergence times; the diversification of curassow seems to have occurred from the Middle Miocene to the end of the Pliocene (9.5 to 1.6 Ma). Vicariance—following marine transgressions, the rise of the Andes, and subsequent changes in river basins in South America—seems to be the major mode of isolation that favored allopatric speciation in the group.
Breeding Biology of Rainbow Bee-Eaters (Merops Ornatus): A Migratory, Colonial, Cooperative Bird
Authors: Boland Christopher R. J.
Published: September 2019

The breeding biology of Rainbow Bee-eaters (Merops ornatus) was studied between 1997 and 2001 in southeast Queensland, Australia. Rainbow Bee-eaters are unusual in that they combine migration and coloniality with cooperative breeding. Birds migrate from islands north of Australia to build nests either solitarily or in colonies containing ≤50 active nests that are attended by socially monogamous pairs or trios (45% of nests). Nesting was essentially forsaken during very dry seasons, whereas hatching success was reduced in wet seasons. Incubation period varied in duration, with chicks emerging 22–31 days after incubation commenced. Eggs hatched either synchronously or, more commonly, asynchronously (88% of clutches), with each chick emerging usually 0–3 days after the previous hatchling in the nest. Asynchronous hatching typically led to a marked size hierarchy within the brood, facilitating starvation of 22% of nestlings that had avoided nest disasters, such as predation or flooding. Duration of the nestling period was also variable, with chicks requiring a further 24–36 days to fledge. Nest predation by native predators—monitor lizards (Varanus varius) and yellow-footed antechinus (Antechinus flavipes)—was relatively low, affecting 10% of nests. In contrast, predation by two introduced species—dingoes (Canis familiaris dingo) and, in particular, cane toads (Bufo marinus)—was extreme, terminating 49% of all nests.
Asymmetric Hybridization and Sex-Biased Gene Flow Between Eastern Spot-Billed Ducks (Anas Zonorhyncha) and Mallards (A. Platyrhynchos) in the Russian Far East
Authors: Kulikova Irina V. , Zhuravlev Yury N. , McCracken Kevin G.
Published: September 2019

The Eastern Spot-billed Duck (Anas zonorhyncha) historically was rare in the southern Russian Far East. However, during the last 60–70 years, its breeding range in East Asia has expanded northwest; Eastern Spot-billed Ducks are breeding increasingly within the range of Mallards (A. platyrhynchos). We collected 120 Eastern Spot-billed Ducks and Mallards from Primorye, Russia, and sequenced 666–667 base pairs (bp) of the maternally inherited mitochondrial DNA (mtDNA) control region and 255 bp of the ornithine decarboxylase intron six (ODC6). Control region and ODC-6 allele sequences revealed two divergent groups of haplotypes and alleles that differ by 1.5% and 2.0%, respectively, and correspond to Avise et al.'s (1990) group A and B mtDNA haplotypes. Group A mtDNA haplotypes occurred in 22 Eastern Spot-billed Ducks and 78 Asian Mallards, and group B haplotypes occurred in 14 Eastern Spot-billed Ducks and 4 Asian Mallards. Moreover, the group B haplotypes that we observed predominantly in Eastern Spot-billed Ducks (i.e. group SB) were monophyletic and diverged by 2–16 substitutions from group B haplotypes previously sequenced from 241 Mottled (A. fulvigula), American Black (A. rubripes), and Mexican ducks (A. diazi), and from North American Mallards. In contrast, type 1 and 2 ODC-6 allele frequencies for Eastern Spot-billed Ducks and Mallards did not differ, but heterozygosity for the former was greater than expected under Hardy-Weinberg equilibrium. Our analysis is the first to document the existence of two divergent haplotype and allele lineages (group A and B, type 1 and 2) in Asian mallard species and suggests that Eastern Spot-billed Ducks are more closely related to North America's Mottled, American Black, and Mexican ducks than they are to Mallards, which occur sympatrically in East Asia. Our data are consistent with the hypothesis that Eastern Spot-billed Ducks and Mallards have hybridized extensively in the Russian Far East. If so, apparent differences in group A and B mtDNA haplotype ratios, effective populations sizes, and migration rates indicate that many more male Eastern Spot-billed Ducks mated with female Mallards and more Eastern Spot-billed Ducks received ODC-6 alleles from Mallards than vice versa. We hypothesize that those differences reflect strong female natal-site fidelity and high levels of male dispersal, and that Mallards significantly outnumber Eastern Spotbilled Ducks in Primorye. Excess heterozygosity in Eastern Spot-billed Ducks (and in Mallards to a lesser extent) is probably maintained by ongoing emigration of Eastern Spot-billed Ducks and Mallards from areas of allopatry outside the Primorye region, where Eastern Spot-billed Ducks and Mallards are predicted to possesses genotypic frequencies historically diagnostic of each species.
Effects of Habitat Disturbance on Reproduction in Black-Capped Chickadees (Poecile Atricapillus) in Northern British Columbia
Authors: Fort Kevin T. , Otter Ken A.
Published: September 2019

Avian species that persist in breeding in disturbed habitats are often thought to be less affected by disturbance than habitat specialists lost following disturbances, yet there is growing evidence that human-altered environments may negatively affect reproductive behavior and nest success of those generalists as well. We compared nest success of Blackcapped Chickadees (Poecile atricapillus) in two adjacent habitats: a mature mixed-wood forest (undisturbed) and a forest regenerating after logging (disturbed). Despite similar breeding densities, proportion of nests that successfully fledged young was lower in the disturbed habitat than in the undisturbed habitat. Abandonment was the most common cause of nest failure. A within-habitat comparison of the social rank of birds revealed that low-ranking birds had lower nest success than high-ranking birds in the disturbed, but not in the undisturbed, habitat. Clutch size and brood size of nests that progressed to the point of hatch did not differ significantly between habitats. Average total number of fledglings produced per pair, though not significantly different, was suggestively lower in the disturbed habitat. Across habitats, nests situated in snags with lower amounts of internal decay were more successful. Successful nests were also located in sites with higher canopy height, low understory density below 1 m, and higher understory density between 2 and 3 m—all attributes generally associated with undisturbed, mature forests in the region. Our results provide evidence that disturbed habitats may represent poor-quality habitat for this forest generalist, and that habitat quality differentially affects individuals, depending on their dominance rank.
Reproduction, Prey, and Habitat of the Aplomado Falcon (Falco Femoralis) in Desert Grasslands of Chihuahua, Mexico
Authors: Macías-Duarte Alberto , Montoya Angel B. , Hunt W. Grainger , Lafón-Terrazas Alberto , Tafanelli Robert
Published: September 2019

A breeding population of Aplomado Falcons (Falco femoralis) remains in the desert grasslands of Chihuahua, Mexico, despite their extirpation in the nearby southwestern United States. We monitored falcon reproduction at 35 territories during 1996-2002, a period of severe drought in the region. To test the influence of prey abundance and vegetation on falcon reproduction, we surveyed avian prey abundance through plot counts in 1998-2002 and characterized vegetation at each plot. Aplomado Falcon productivity declined from 1.57 fledglings per occupied territory in 1997 to 0.63 in 2002 at the larger of two study areas, a trend consistent with cumulative effects of consecutive years of low rainfall. Reproduction in the smaller area remained low throughout the study. Both productivity and incubation start date were significantly associated with prey bird abundance. Summer rain most likely influenced falcon reproduction by affecting seed abundance and therefore abundance of granivorous prey birds the following winter and spring. Falcons nested in open grasslands with sparse woody vegetation, an adaptation likely related to higher prey vulnerability and fewer predators. However, important prey birds were positively correlated with woody-plant density, which suggests that proximity of shrublands increased nest-site suitability.
Corticosterone Secretion, Energetic Condition, and a Test of the Migration Modulation Hypothesis in the Hermit Thrush (Catharus Guttatus), A Short-Distance Migrant
Authors: Long Jennifer A. , Holberton Rebecca L.
Published: September 2019

Recent evidence suggests that migration may be extremely important in limiting populations of migratory songbirds. Understanding the relationship between changes in cor- ticosterone secretion and energy reserves during migration is essential to understanding how environmental conditions such as weather, food availability, predation pressure, and habitat quality may be affecting birds en route. Several studies have found that baseline corticosterone is often elevated, and response to capture and handling stress reduced (migration modulation hypothesis), in birds sampled during the migratory period. However, because neither corticos- terone secretion nor energetic condition within groups of birds sampled either in laboratory or in field varied significantly (Holberton et al. 1996, Holberton 1999), it was unknown whether corticosterone secretion could be modulated to track changes in energetic condition within the migratory period. Here, we investigated patterns of corticosterone secretion associated with variation in energetic condition in 18 free-living Hermit Thrushes (Catharus guttatus) sampled during autumn migration. Mean baseline corticosterone (mean ± SE) was 37.22 ± 7.70 ng mL−1 and increased during the 30-min interval up to 54.52 ± 6.01 ng mL−1. Lean birds were more likely to exhibit higher levels of baseline corticosterone and a reduced adrenocortical response, compared with birds that had greater energy reserves. Collectively, the results support the migration modulation hypothesis and illustrate that baseline and stress-induced corticosterone secretion can be modulated to meet the changing energy needs of birds during the migratory period.
Brood Parasitism and Egg Transfer in Cave Swallows (Petrochelidon Fulva) and Cliff Swallows (P. Pyrrhonota) in South Texas
Authors: Weaver Heath B. , Brown Charles R.
Published: September 2019

We studied the frequency of intraspecific brood parasitism and physical transfer of eggs between nests in colonially nesting Cave Swallows (Petrochelidon fulva) and Cliff Swallows (P. pyrrhonota) in south Texas in 2001. Although the eggs of the two species look similar, frequency of brood parasitism in each species was unaffected by presence of the other species, which suggests that the parasitism we observed was largely by conspecifics. We detected brood parasitism in 4.6–5.0% of Cave Swallow nests and in 10.7–11.9% of Cliff Swallow nests. Brood parasitism was not significantly related to colony size in either species, to eventual success of the host nest, or to overall colony nesting success (a measure of environmental risk). We detected evidence of physical transfer of eggs in 0.7–2.0% of nests of these species. Cliff Swallows parasitized nests more often than Cave Swallows, but the frequencies of brood parasitism and egg transfer in the two species in south Texas appeared broadly comparable to those reported for Cliff Swallows in Nebraska, despite geographic differences in habitat, seasonality, breeding phenology, and levels of sociality between the populations.
Effects of Tagging on Behavior, Provisioning, and Reproduction in the Common Murre (Uria Aalge), A Diving Seabird
Authors: Hamel Nathalie J. , Parrish Julia K. , Conquest Loveday L.
Published: September 2019

Telemetry devices used on seabirds have been shown to affect their behavior, reproduction, and survival. However, studies have primarily been limited to larger species, and results are occasionally equivocal. We quantified tag retention time and effects of attaching subcutaneous anchor radiotransmitters on behavior, provisioning, and reproduction in the Common Murre (Uria aalge), a medium-bodied seabird. Between 1999 and 2001, we tagged 48 Common Murres on Tatoosh Island, Washington. Subsequently, 46 birds were detected during colony observation, radiotracking, or both. Activity budgets and time spent at the nest site did not differ between tagged birds and their untagged mates. However, tagged birds made fewer but longer trips away from the nest and provisioned their chicks significantly less than their mates did (0.07 ± 0.02 fish h−1 and 0.18 ± 0.02 fish h−1, respectively). Prey size and energy content did not differ. Despite the disparity in provisioning rates at the individual level, tagged pairs and control pairs had equivalent energy-delivery rates and reproductive success. Tagging effects did not persist in the long term, because percentage of tagged birds returning to the colony the next breeding season was similar to percentage of birds without tags, and tagged birds' reproductive success was comparable to that of the rest of the colony. Subcutaneous anchor attachments compared favorably to glued tags and implanted transmitters in terms of retention time and survival, respectively. We recommend using subcutaneous anchor transmitters for medium-bodied seabirds that employ flexible foraging strategies. Possible exceptions are years of poor food availability, when the capacity to absorb tag effects may be lower.
Effect of Refeeding on Growth, Development, and Behavior of Undernourished Bank Swallow (Riparia Riparia) Nestlings
Authors: Brzȩk Pawel , Konarzewski Marek
Published: September 2019

Nestlings of aerial insectivores adjust their energetics, behavior, and development of internal organs in response to food shortages and subsequent improvements in feeding conditions. Here, we present results of laboratory refeeding of Bank Swallow (Riparia riparia) nestlings, which were undernourished between 4 and 7 days of age. During a subsequent three-day-long refeeding, their body mass did not catch up with that of individuals continuously fed ad libitum. However, refed young managed to compensate for delayed growth of pectoral muscles, small intestines, and fully restored fat reserves. Their resting metabolic rates and body temperatures increased to values similar to those of nestlings fed ad libitum. In contrast, digestive activity of their guts (quantified as carrier-mediated intestinal brushborder uptake rate of L-proline) was reduced, as compared with the period of undernutrition. Likewise, high locomotor activity observed during food shortage was significantly reduced upon refeeding. Furthermore, differences in body mass between nest mates, which had earlier modulated both locomotor activity and physiological responses to food shortage, had no effect on mobility and physiology of refed nestlings. Our results indicate that even a short, three-day period of refeeding triggered conspicuous acceleration of growth and development of vital internal organs in previously undernourished nestlings. However, that was not accompanied by significant compensatory whole-body growth (defined as a period of above-normal rapid growth, relative to age).
Penguins
Authors: Stokes David
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.
Molecular Markers, Natural History, and Evolution. 2nd edition
Authors: Lovette Irby J.
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.
Alarm Calling in Sri Lankan Mixed-Species Bird Flocks
Authors: Goodale Eben , Kotagama Sarath W.
Published: September 2019

Vocal alarm calls are important to the vigilance and likely the organization of mixed-species flocks, but community-wide studies of alarm calling in flocks are lacking. We investigated which species alarm-call, and the characteristics of their calls, in a large flock system of a Sri Lankan rainforest. We recorded naturally elicited alarm calls during several attacks by Accipiter hawks and while following flocks for 10 h. We then artificially elicited alarms by throwing a stick to the side of the flock, in a total of 70 trials at 30 flock sites. The Orange-billed Babbler (Turdoides rufescens) was the most frequent caller to both the artificial and natural stimuli, followed by the Greater Racket-tailed Drongo (Dicrurus paradiseus). Several other species also called, and multiple species often called to the same stimulus (in 23 trials, and in all of the hawk attacks). The species differed in their rapidity of response and in their sensitivity to different natural stimuli. Calls of the gregarious babbler usually provided a first, unreliable warning of an incoming threat, whereas later calls of other species emphasized the seriousness of the threat. We suggest that birds in mixed-species flocks may be particularly aware of aerial predators for two reasons: (1) a “numbers effect,” whereby nongregarious species are more aware of predators when surrounded by large numbers of other species; and (2) an “information effect,” whereby species differ in the information available in their alarm calls, leading to an accumulation of information in a mixed-species flock.

Llamadas de Alarma en Bandadas Mixtas de Aves en Sri Lanka
Phylogeny of Titmice (Paridae): II. Species Relationships Based on Sequences of the Mitochondrial Cytochrome-B Gene
Authors: Gill Frank B. , Slikas Beth , Sheldon Frederick H.
Published: September 2019

We present a phylogenetic hypothesis for 40 species in the bird family Paridae, based on comparisons of nucleotide sequences of the mitochondrial cytochrome-b gene. Parids, including tits and chickadees, are an older group than their morphological stereotypy suggests. The longest cytochrome-b distances between species reach 12% in uncorrected divergence. With the exception of one thrasher-like terrestrial tit species of the Tibetan plateau (Pseudopodoces humilis), morphological and ecological stasis have prevailed since the initial parid radiation in the Old World during the mid-Tertiary.

All trees support monophyly of the family Paridae, which includes Parus (sensu lato) and the monotypic Oriental genera Sylviparus, Melanochlora, and Pseudopodoces. Within the clade of chickadees and gray tits (Parus, subgenus Poecile), three Old World species, Parus lugubris of the eastern Mediterranean and Balkan regions, P. superciliosus of high elevations in the Himalayas of western China, and P. varius of the Orient are sisters to all other species. The Eurasian crested titmice (subgenus Lophophanes) and North American crested titmice (subgenus Baeolophus) are sister groups. Our data suggest two colonizations of the New World by parids in the late Tertiary. The ancestor of modern Baeolophus colonized North America 4 mya, and the ancestor of all North American chickadees colonized North America 3.5 mya.

Phylogénie chez la mésange (Paridés): II. Relations entre les espèces basées sur des séquences du gène mitochondrial cytochrome-b
Molecular Phylogenetic Relationships Among the Geositta Miners (Furnariidae) and Biogeographic Implications for Avian Speciation in Fuego-Patagonia
Authors: Cheviron Z. A. , Capparella Angelo P. , Vuilleumier François
Published: September 2019

Pleistocene glacial cycles have often been hypothesized to provide vicariant mechanisms leading to allopatric speciation in a wide range of southern South American (Fuegian and Patagonian) avian taxa. Few of those biogeographic hypotheses, however, have been rigorously tested using phylogenetic analysis. We examined sequence variation in three mitochondrial gene fragments (cytochrome b, ND2, and ND3) to construct a molecular phylogeny for the South American genus Geositta (Furnariidae) and to test the interrelated hypotheses that Geositta cunicularia and G. antarctica are sister species that originated from a common ancestor while isolated in glacial refugia during Pleistocene glacial events in Fuego-Patagonia. Sequence data were obtained for all 10 currently recognized species of Geositta as well as Geobates poecilopterus and two outgroup taxa (Upucerthia ruficauda and Aphrastura spinicauda). We found levels of sequence divergence among Geositta species to be high, ranging from 7.4% to 16.3%. Our phylogenetic reconstructions clearly indicate relationships among Geositta species that differ considerably from those of traditional Geositta phylogeny. These data also strongly suggest that Geositta, as currently defined, is paraphyletic, with Geobates being embedded within Geositta. Our data do not support the hypothesized sister relationship between G. antarctica and G. cunicularia. Instead, they suggest that Geositta consists of two distinct clades, with antarctica and cunicularia falling into different clades. The high levels of sequence divergence among Geositta species, lack of a sister relationship between cunicularia and antarctica, and placement of Fuego-Patagonian antarctica into a clade consisting of two high-Andean (saxicolina and isabellina) and one coastal-west-slope (maritima) species demonstrate that the evolutionary history of Geositta is much older and far more complex than a simple model of allopatric speciation in glacial refugia would suggest.

Filogenia Molecular del Género Geositta (Furnariidae) e Implicaciones Biogeográficas para la Especiación de la Aves en Tierra del Fuego y Patagonia
Sex Differences in Singing and Duetting Behavior of Neotropical Rufous-and-White Wrens (Thryothorus Rufalbus)
Authors: Mennill Daniel J. , Vehrencamp Sandra L.
Published: September 2019

In many tropical bird species, males and females sing together in coordinated vocal duets. Although studies of duetting present unique opportunities for understanding conflict and cooperation between the sexes, very few investigations describe the similarities and differences between male and female singing behaviors. Here, we present the first detailed account of the singing behavior of Rufous-and-white Wrens (Thryothorus rufalbus), a resident tropical duetting songbird. Male and female songs share a similar structure, yet show pronounced sex differences. Male songs have lower frequency characteristics and more repeated trill syllables, and often sound louder than female songs. Males sing more than females, and only males show elevated song output at dawn. Both males and females have song repertoires. Males have an average repertoire size of 10.8 song types, whereas females have a significantly smaller average repertoire size of 8.5 song types. Although males share proportionately more of their song types with neighbors than females do, both sexes share more song types with nearby individuals than with distant individuals. Breeding partners combine their solo songs to create duets. Duets assume a variety of different forms, ranging from simple, overlapping male and female songs to complex combinations of multiple male and female songs. Most duets (73%) are created by females responding to male song. Males respond to female-initiated duets with shorter latencies than when females respond to male-initiated duets. Each pair sings certain combinations of song types in duets more often than can be explained by random association, which demonstrates that Rufous-and-white Wrens have duet types. The most common duet type was different for each pair. Our results show that Rufous-and-white Wrens have pronounced sex differences in song structure, singing activity, repertoire size, repertoire sharing, and duetting behavior.

Diferencias entre Sexos en el Canto y Comportamiento de Dueto en Thryothorus rufalbus
Foraging and Territory Economics of Sexually Dimorphic Purple-Throated Caribs (Eulampis Jugularis) on Three Heliconia Morphs
Authors: Temeles Ethan J. , Goldman Robin S. , Kudla Alexei U.
Published: September 2019

We observed territorial Purple-throated Caribs (Eulampis jugularis) on three Heliconia morphs (H. caribaea and the red-green and green morphs of H. bihai) on the island of St. Lucia, West Indies, to examine how calculated costs and benefits compared with observed patterns of Heliconia use. Across the three years of our study, H. caribaea territories defended by Purple-throated Carib males were significantly smaller in area and had higher densities of flowers than red-green H. bihai territories, and both kinds of Heliconia territories defended by males were smaller and had higher densities of flowers than the green H. bihai territory maintained by a female. In the period (0630 to 1400 hours) during which birds maintained territories, total maintenance costs were more than met by energy obtained from territories, but only 2 of 13 territories provided sufficient nectar to meet birds' energy requirements for 24 h. Birds supplemented their energy intake from Heliconia territories by foraging at flowers in the rainforest canopy, and the percentage of time a territorial bird spent foraging in the canopy was inversely correlated with energy production on its Heliconia territory. The smaller territory areas and higher flower densities of H. caribaea territories lowered males' foraging time and energy costs per flower on H. caribaea as compared with red-green H. bihai territories, theoretically allowing them to meet their energy demands in less time and at lower cost. Males' estimated foraging time and energy costs were greatest at the green morph of H. bihai; compared with females, they would save a higher proportion of time and energy by foraging at H. caribaea and the red-green morph of H. bihai. That asymmetry between males and females in relative gains from foraging at each of the three Heliconia morphs may further reinforce resource partitioning between them, in addition to differences in size and fighting abilities.

Economía de Forrajeo y Territorialidad en la Especie Sexualmente Dimórfica Eulampis jugularis en Tres Formas de Heliconia
Dispersal by Juvenile American Crows (Corvus Brachyrhynchos) Influences Population Dynamics Across a Gradient of Urbanization
Authors: Withey John C. , Marzluff John M.
Published: September 2019

American Crow (Corvus brachyrhynchos) populations are increasing across North America, often at high rates in urban areas. A monthly survey of American Crows in the Seattle Christmas Bird Count (CBC) circle suggested that winter counts reflected American Crow abundance at other times of the year, so we used CBC results for American Crows as a measure of population trend. In the Seattle area, local survival and fecundity appear unable to account for exponential population growth. We tested the hypothesis that juvenile dispersal from outlying suburban and exurban areas contributes to growth in the urban population by radiotagging 56 juveniles 5–46 km away from the central business district of Seattle and tracking their movements. Juvenile American Crows’ centers of activity were 0.2–22.2 km away from their natal territory during the first 3–12 months after fledging. An estimated 45% survived one year. Movements of dispersing American Crows varied in their consistency with simulated random-walk paths; the data suggested that, at the population level, American Crows were not drawn into urban areas, though some individuals may have been. Movements of dispersers produced a net influx into the city, because of greater reproductive success outside the city than in it. Simulations of urban population growth that included immigrants and emigrants accounted for most of the observed growth, which indicates the importance of distant suburban and exurban breeding pairs to urban population dynamics.

La Dispersión de Juveniles de Corvus brachyrhynchos Influencia la Dinámica Poblacional a lo Largo de un Gradiente de Urbanización
Feather-Degrading Bacteria do not Affect Feathers on Captive Birds
Authors: Cristol Daniel A. , Armstrong Jessica L. , Whitaker Justine M. , Forsyth Mark H.
Published: September 2019

Attention has recently been focused on microbes that occur in the plumage of wild birds and can degrade feathers under laboratory conditions and in poultry-waste composters. In particular, Bacillus licheniformis, a soil bacterium, was found in the plumage of many birds netted in eastern North America, and poultry feathers were rapidly broken down when incubated in a suspension of this bacterium (Burtt and Ichida 1999). If feather-degrading microbes affect wild birds under normal conditions, they may have played an important role in the evolution of molt, plumage color, and sanitation behavior, such as sunning and preening. We performed the first test on whether a feather-degrading bacterium can degrade feathers of live birds housed outdoors under seminatural conditions. We found no evidence that B. licheniformis degraded wing feathers of Northern Cardinals (Cardinalis cardinalis) when applied twice (with a two-week interval) during the winter, despite the fact that it degraded Northern Cardinal feathers when incubated in our laboratory. In a second experiment, we found no evidence that B. licheniformis degraded feathers of European Starlings (Sturnus vulgaris) when applied twice (with a one-week interval) during the summer, despite the fact that birds were housed in humid conditions that should have favored the growth of B. licheniformis.

Las Bacterias que Degradan Plumas no Afectan las Plumas de Aves en Cautiverio
Relationships Among Mercury Concentrations, Hormones, and Nesting Effort of White Ibises (Eudocimus Albus) in the Florida Everglades
Authors: Heath Julie A. , Frederick Peter C.
Published: September 2019

Mercury, a common wetland pollutant, can affect wildlife populations through acute toxicity or through physiological effects that modify behavior and negatively influence reproductive success. We compared body-feather mercury concentrations of free-living male and female adult White Ibises (Eudocimus albus) during three breeding seasons in the Florida Everglades and examined the relationships among mercury, hormone concentrations, and body-condition scores. Female White Ibises consistently had lower mercury concentrations than males. Prebreeding females' estradiol concentrations were negatively correlated with mercury concentrations. However, we found no relationship between mercury and female testosterone, progesterone, and corticosterone concentrations. Incubating male White Ibises showed a significant positive relationship between testosterone and mercury concentrations, but no other significant hormonal correlations with mercury concentrations. We used a seven-year standardized data set of Great Egret (Ardea alba) chick-feather mercury concentrations as a measure of temporal changes in mercury bioavailability in the Everglades and related that measure to annual numbers of White Ibis nests. White Ibis nesting was negatively correlated with the mercury exposure index. Low numbers of nesting White Ibises may have been the result of fewer birds nesting or high abandonment rates. Our results suggest that mercury exposure may cause fewer birds to nest or more birds to abandon nests because of subacute effects on hormone systems. However, the results are correlative; they call for further investigation in free-living populations and in the laboratory.

Relaciones entre las Concentraciones de Mercurio, Hormonas y el Esfuerzo de Nidificación de Eudocimus albus en los Everglades, Florida
Effectiveness of Call-Broadcast Surveys for Monitoring Marsh Birds
Authors: Conway Courtney J. , Gibbs James P.
Published: September 2019

Many species of marsh birds (e.g. rails and bitterns) are believed to be declining in North America, yet we lack an effective monitoring program to estimate their population trends. Broadcast of prerecorded calls to elicit vocalizations is a commonly used method in surveys of marsh birds, but whether gains in detection and index precision outweigh the drawbacks of call-broadcast is unclear. To evaluate the effectiveness of call-broadcast surveys, we pooled marsh-bird survey data from 8,047 point-count surveys contributed by 11 cooperators and compared numbers of birds detected and variation in numbers detected between call-broadcast and passive surveys. For most rails (particularly Virginia Rails [Rallus limicola]), call-broadcast surveys were effective at increasing the detection probability (e.g. average number of Virginia Rails detected per occupied point was 1.25 for call-broadcast surveys and 0.17 for passive surveys). The proportion of points at which no birds were detected was high for all species (range 74–99%) and was slightly lower on call-broadcast surveys as compared with passive surveys. Coefficient of variation (CV) among replicate surveys was higher for passive surveys, particularly for rails (average CV in number of birds detected per point was 209% for passive surveys and 189% for call-broadcast surveys). On the basis of those results, we recommend a marsh-bird monitoring protocol that includes an initial passive period followed by a period of call-broadcast to provide survey data that incorporate the benefits while avoiding the drawbacks of call-broadcast. We also recommend separating both the passive and the call-broadcast periods into 1-min subsegments that will allow estimates of components of detection probability within the monitoring effort.

Efectividad de Censos que Reproducen Vocalizaciones Pregrabadas para Monitorear Aves de Pantano
Molecular Evidence for Recent Radiation in Southern Hemisphere Masked Gulls
Authors: Given Andrew D. , Mills James A. , Baker Allan J.
Published: September 2019

Masked gulls are believed, on the basis of morphological and recent molecular work, to be a monophyletic group within the Laridae, but relationships of species within the group are not well resolved. We used sequence data from four mitochondrial DNA genes (ND2, ND5, ATPase6, and ATPase 8) totaling >3,600 base pairs to clarify relationships among the species and test competing hypotheses about their origin and biogeography. Monophyly of the masked gulls was confirmed. We also found strong support for a clade including all Southern Hemisphere masked gulls as well as a lone Northern Hemisphere representative, the Black-headed Gull (Larus ridibundus). The Australasian taxa form a well-supported clade, in which the Black-billed Gull (L. bulleri) is sister to the Red-billed Gull (L. novaehollandiae scopulinus) of New Zealand and the Australian Silver Gull (L. n. novaehollandiae). Another well-supported clade includes the Black-headed Gull as sister to the South African Hartlaub's Gull (L. hartlaubii) and the Gray-hooded Gull (L. cirrocephalus) of Africa and South America. The strongly supported position of L. ridibundus within the “southern clade” suggests that it originated from a Southern Hemisphere ancestor and recently dispersed into the Northern Hemisphere. Estimates of divergence times using rate-smoothing methods are consistent with those from previous molecular work and suggest that (1) masked gulls diverged from other gulls <2 mya and (2) much of the radiation in the group occurred in the last 600,000 years.

Preuve moléculaire de la radiation récente chez les mouettes “masquées” de l'hémisphère sud
Renesting Determines Seasonal Fecundity in Songbirds: What do we Know? What Should we Assume?
Authors: Grzybowski Joseph A. , Pease Craig M.
Published: September 2019

Because of the difficulty of following female songbirds through an entire breeding season, field ornithologists are seldom able to directly measure seasonal fecundity (defined as number of offspring produced per female during an entire breeding season). Instead, it is more commonly inferred from some measure of nest-productivity data (e.g. average number of offspring fledged per nesting attempt) using algorithms that make assumptions about the propensity of females to renest after a nest failure or after successfully fledging a brood. Recent analyses have often assumed set maximum numbers of nesting attempts and successful broods, and that all females breed up to those maxima. However, whereas data from songbirds intensively followed for an entire breeding season show that they are capable of up to 4–8 nesting attempts, many authors, in estimating seasonal fecundity, assume a maximum of only 1–4 nesting attempts. We applied a model to a Prairie Warbler (Dendroica discolor) data set (Nolan 1978) that allowed direct comparisons of (1) seasonal-fecundity estimates obtained assuming fixed maximum numbers of renestings and broods with (2) estimates obtained assuming that numbers of renesting attempts and successful nests are constrained only indirectly by length of breeding season. Although results under the latter assumption are concordant with Nolan's (1978) direct empirical measure of Prairie Warbler seasonal fecundity, estimates under assumptions of fixed maxima of renestings or broods are in serious error for many parameter choices. As such, our analyses disclose that essentially all estimates of seasonal fecundity in the literature derived by assuming a limited maximum number of nesting attempts or of successful broods are biased. Most commonly, when nest mortality is high, seasonal fecundity is underestimated; in some cases where nest mortality is low, seasonal fecundity is overestimated. We recommend that researchers estimating seasonal fecundity from nest-productivity data use a model that explicitly sets breeding-season length and thereby only indirectly constrains the possible number of nesting attempts and successful broods.

La Nidificación Repetida Determina la Fecundidad Estacional en las Aves Canoras: ¿Qué Sabemos? ¿Qué Deberíamos Suponer?