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Eben H. Paxton - One of the best experts on this subject based on the ideXlab platform.
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A technique to produce aluminum color bands for avian research
Journal of Field Ornithology, 2020Co-Authors: Thomas J. Koronkiewicz, Eben H. Paxton, Mark K. SoggeAbstract:Abstract We developed a technique to produce metal (aluminum) color bands, in response to concerns about leg injuries caused by celluloid-plastic color bands applied to Willow Flycatchers (Empidonax traillii). The technique involves color-anodized aluminum bands (unnumbered blanks and federal numbered bands), with auto pin-striping tape and flexible epoxy sealant, to create a variety of solid, half- and triple-split colors. This allows for hundreds of unique, high-contrast color combinations. During six consecutive years of application, these colored metal bands have resisted color fade compared to conventional celluloid-plastic bands, and have reduced leg injuries in the flycatcher. Although not necessarily warranted for all color-banding studies, these metal bands may provide a lower-impact option for studies of species known to be impacted by plastic color bands.
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geographic variation in the plumage coloration of willow flycatchers Empidonax traillii
Journal of Avian Biology, 2010Co-Authors: Mark K. Sogge, Eben H. Paxton, Thomas J. Koronkiewicz, Mary Anne Mcleod, Tad C. TheimerAbstract:The ability to identify distinct taxonomic groups of birds (species, subspecies, geographic races) can advance ecological research efforts by determining connectivity between the non-breeding and breeding grounds for migrant species, identifying the origin of migrants, and helping to refine boundaries between subspecies or geographic races. Multiple methods are available to identify taxonomic groups (e.g., morphology, genetics), and one that has played an important role for avian taxonomists over the years is plumage coloration. With the advent of electronic devices that can quickly and accurately quantify plumage coloration, the potential of using coloration as an identifier for distinct taxonomic groups, even when differences are subtle, becomes possible. In this study, we evaluated the degree to which plumage coloration differs among the four subspecies of the willow flycatcher Empidonax traillii, evaluated sources of variation, and considered the utility of plumage coloration to assign subspecies membership for individuals of unknown origin. We used a colorimeter to measure plumage coloration of 374 adult willow flycatchers from 29 locations across their breeding range in 2004 and 2005. We found strong statistical differences among the mean plumage coloration values of the four subspecies; however, while individuals tended to group around their respective subspecies’ mean color value, the dispersion of individuals around such means overlapped. Mean color values for each breeding site of the three western subspecies clustered together, but the eastern subspecies’ color values were dispersed among the other subspecies, rather than distinctly clustered. Additionally, sites along boundaries showed evidence of intergradation and intermediate coloration patterns. We evaluated the predictive power of colorimeter measurements on flycatchers by constructing a canonical discriminant model to predict subspecies origin of migrants passing through the southwestern U.S. Considering only western subspecies, we found that individuals can be assigned with reasonable certainty. Applying the model to migrants sampled along the Colorado River in Mexico and the U.S. suggests different migration patterns for the three western subspecies. We believe that the use of plumage coloration, as measured by electronic devices, can provide a powerful tool to look at ecological questions in a wide range of avian species. The wide range of colors and patterns displayed in the plumage of birds has historically played an important role in elucidating taxonomic groups, particularly in the identification of species, subspecies, and geographic races
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Age, Habitat, and Yearly Variation in the Diet of a Generalist Insectivore, the Southwestern Willow Flycatcher
The Condor, 2008Co-Authors: Scott L. Durst, Tad C. Theimer, Eben H. Paxton, Mark K. SoggeAbstract:ABSTRACT Characterizing avian diet is complex, especially for generalist insectivores, as food resources can vary over space and time, and individuals of different sexes and ages may consume different food. We examined diet of a generalist insectivore, the Southwestern Willow Flycatcher (Empidonax traillii extimus), at Roosevelt Lake in central Arizona from 2000 to 2004, determined from 344 fecal samples. We found that five prey categories accounted for 70% of the proportional abundance in flycatcher diet: Hymenoptera, Diptera, Cicadellidae, Coleoptera, and Formicidae, although the relative amounts of these and other taxa differed significantly among years. We detected no differences in diet between sexes of adults, but adults and nestlings differed, with higher proportions of Hymenoptera in adult samples and more Diptera in nestling samples. Using a subset of samples, we compared flycatcher diet in habitat patches dominated by native cottonwood (Populus fremontii) and willow (Salix gooddingii), exotic sa...
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TERRITORIALITY, SITE FIDELITY, AND SURVIVORSHIP OF WILLOW FLYCATCHERS WINTERING IN COSTA RICA
The Condor, 2006Co-Authors: Thomas J. Koronkiewicz, Mark K. Sogge, Charles Van Riper, Eben H. PaxtonAbstract:Abstract We studied wintering Willow Flycatchers (Empidonax traillii) in two seasonal freshwater wetland habitats in northwestern Costa Rica during five boreal winters, to determine habitat occupancy, overwinter and between-year site and territory fidelity, and the degree to which the sexes maintain and defend winter territories. Both males and females used agonistic displays, song, and other vocalizations to maintain and defend mutually exclusive winter territories. Males were generally more abundant than females, but this varied by site and year. There was no significant difference in male and female territory size, nor any indication of sexual habitat segregation. Similarity in morphology and aggressiveness between the sexes may account for the lack of habitat segregation and the ability of females to maintain territories at wintering sites. Each year, 80%–92% of banded flycatchers that were present in midwinter remained at the site until late winter; of these, 86%–100% of individuals maintained the sa...
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NESTLING SEX RATIO IN THE SOUTHWESTERN WILLOW FLYCATCHER
The Condor, 2002Co-Authors: Eben H. Paxton, Mark K. Sogge, Tracy Mccarthey, Paul S KeimAbstract:Abstract Using molecular-genetic techniques, we determined the gender of 202 Southwestern Willow Flycatcher (Empidonax traillii extimus) nestlings from 95 nests sampled over a five-year period. Overall nestling sex ratio did not vary significantly from 50:50 among years, by clutch order, or by mating strategy (monogamous vs. polygamous pairings). However, we did observe significant differences among the four sites sampled, with sex ratios biased either toward males or females at the different sites. Given the small population sizes and geographic isolation of many of the endangered subspecies' breeding populations, sex-ratio differences may have localized negative impacts. Cociente de Sexos en Polluelos de Empidonax traillii extimus Resumen. Utilizando tecnicas moleculares determinamos el sexo de 202 polluelos de Empidonax traillii extimus pertenecientes a 95 nidos que fueron muestreados durante un periodo de cinco anos. En general, el cociente de sexos no vario significativamente de 50:50 entre anos, ya ...
Ned K Johnson - One of the best experts on this subject based on the ideXlab platform.
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the role of ecologic diversification in sibling speciation of Empidonax flycatchers tyrannidae multigene evidence from mtdna
Molecular Ecology, 2002Co-Authors: Ned K Johnson, Carla CiceroAbstract:: Avian genera characterized by sibling species with distinctive habitat preferences present an evolutionary enigma in view of the more commonplace occurrence of syntopic congeners that differ strikingly in colour and pattern. No existing theory has explained the evolutionary background that led to these differences. Here we propose that great phenotypic similarity among some groups of sibling species limits their coexistence and that clues to their radiation can be seen in patterns of geographical occurrence. To illustrate our thesis we focused on the New World flycatcher genus Empidonax, a group of 15 species notorious for their great phenotypic similarity. Using 3069 base pairs of mitochondrial DNA from four genes, we produced a complete molecular phylogeny that identified four clades, three of which represent close relatives. The fourth clade includes only E. virescens, which apparently has no close living relatives. The majority of species, including many distant relatives, are completely (58.1%) or essentially (6.7%) allopatric in breeding distribution and exhibit striking ecological segregation into distinctive climate-vegetation zones. Even where ranges overlap, occupancy of the same habitat by different species is rare. Phylogenetic and distributional patterns in Empidonax suggest a peripatric model of stepwise colonization and then range expansion of small groups of pioneers during glacial periods into initially enlarging, distinctive habitats destined to be widespread during interglacials. Vicariance is not indicated in the absence of barriers of appropriate age and geographical position. Rapoport's rule that northern species have larger ranges than southern species is strongly supported.
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phylogeny and character evolution in the Empidonax group of tyrant flycatchers aves tyrannidae a test of w e lanyon s hypothesis using mtdna sequences
Molecular Phylogenetics and Evolution, 2002Co-Authors: Carla Cicero, Ned K JohnsonAbstract:Abstract We sequenced mitochondrial DNA from four protein-coding genes for 26 taxa to test W. E. Lanyon's hypothesis of intergeneric relationships and character evolution in the Empidonax group of tyrant flycatchers. Three genera in this group (Empidonax, Contopus, and Sayornis) successfully occupy north temperate habitats for breeding, while the remaining genera (Mitrephanes, Cnemotriccus, Aphanotriccus, Lathrotriccus, and Xenotriccus) are restricted to neotropical latitudes. Lanyon hypothesized two major clades in the group based on differences in syringeal morphology and proposed relationships among genera using a combination of morphologic, behavioral, and allozymic characters. The mtDNA data strongly support Lanyon's division of genera into two clades. In addition, the molecular and nonmolecular data sets agree in uniting Aphanotriccus and Lathrotriccus as sister taxa, with Cnemotriccus as basal to these genera. Species of Aphanotriccus, Lathrotriccus, and Cnemotriccus form a clade that exploits a distinctive nesting niche relative to other members of the Empidonax group. Within the second major clade, mtDNA sequences support a reconstruction based on allozymes that places Contopus and Empidonax as sister taxa. This hypothesis contradicts that of Lanyon, who allied Contopus with Mitrephanes on the basis of similarity in foraging mode. Genera in the Empidonax group are members of a larger assemblage that radiated in South America. Occupancy of temperate habitats by certain genera in this group is coincident with their evolution of migratory behavior and with independent diversification in foraging modes that reduces potential competition in sympatry.
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evolutionary genetics of flycatchers iii variation in Empidonax hammondii aves tyrannidae
Canadian Journal of Zoology, 1991Co-Authors: Ned K Johnson, Jill A MartenAbstract:We assessed variability at 36 structural gene loci in 149 individuals from nine breeding populations of the Hammond's Flycatcher (Empidonax hammondii), a species showing striking morphologic homogeneity over a nesting distribution spanning 30 degrees of latitude. Although moderately polymorphic (44.4%) at these loci, the species demonstrated low levels of mean observed heterozygosity (0.026), mean percentage of polymorphic loci (9.56), and mean number of alleles per locus (1.19), perhaps as a result of past population bottlenecks. Geographic genetic structuring was minimal (FSt = 0.043) and paralleled the lack of morphologic variation. Six of the eight unique alleles recorded occurred in Oregon, near the center of present abundance. Gene flow, as estimated by the rare allele method, was moderately high to high at 8–31 individuals per generation. Because most or all of the modern distribution of the species in western Canada and Alaska was either covered by ice or otherwise unsuitable for occupancy until t...
Mark K. Sogge - One of the best experts on this subject based on the ideXlab platform.
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Demographic characteristics and population modeling: Chapter 8 in Status, ecology and conservation of the Southwestern Willow Flycatcher (RMRS-GTR-60)
2020Co-Authors: Scott H. Stoleson, Mary J Whitfield, Mark K. SoggeAbstract:This publication was prepared in response to a need expressed by southwestern agencies and organizations for a comprehensive assessment of the population status, history, biology, ecology, habitats, threats, and conservation of the southwestern willow flycatcher (Empidonax traillii extimus). The southwestern willow flycatcher was federally listed as an Endangered subspecies in 1995. A team of flycatcher experts from multiple agencies and organizations identified components of the publication, wrote chapters, and cooperatively assembled management recommendations and research needs. We hope this publication will be useful in conserving populations and habitats of the southwestern willow flycatcher. Financial assistance for preparing this report was provided by the Southwest Region and Rocky Mountain Research Station's Rio Grande Ecosystem Program of the U.S. Forest Service.
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A technique to produce aluminum color bands for avian research
Journal of Field Ornithology, 2020Co-Authors: Thomas J. Koronkiewicz, Eben H. Paxton, Mark K. SoggeAbstract:Abstract We developed a technique to produce metal (aluminum) color bands, in response to concerns about leg injuries caused by celluloid-plastic color bands applied to Willow Flycatchers (Empidonax traillii). The technique involves color-anodized aluminum bands (unnumbered blanks and federal numbered bands), with auto pin-striping tape and flexible epoxy sealant, to create a variety of solid, half- and triple-split colors. This allows for hundreds of unique, high-contrast color combinations. During six consecutive years of application, these colored metal bands have resisted color fade compared to conventional celluloid-plastic bands, and have reduced leg injuries in the flycatcher. Although not necessarily warranted for all color-banding studies, these metal bands may provide a lower-impact option for studies of species known to be impacted by plastic color bands.
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geographic variation in the plumage coloration of willow flycatchers Empidonax traillii
Journal of Avian Biology, 2010Co-Authors: Mark K. Sogge, Eben H. Paxton, Thomas J. Koronkiewicz, Mary Anne Mcleod, Tad C. TheimerAbstract:The ability to identify distinct taxonomic groups of birds (species, subspecies, geographic races) can advance ecological research efforts by determining connectivity between the non-breeding and breeding grounds for migrant species, identifying the origin of migrants, and helping to refine boundaries between subspecies or geographic races. Multiple methods are available to identify taxonomic groups (e.g., morphology, genetics), and one that has played an important role for avian taxonomists over the years is plumage coloration. With the advent of electronic devices that can quickly and accurately quantify plumage coloration, the potential of using coloration as an identifier for distinct taxonomic groups, even when differences are subtle, becomes possible. In this study, we evaluated the degree to which plumage coloration differs among the four subspecies of the willow flycatcher Empidonax traillii, evaluated sources of variation, and considered the utility of plumage coloration to assign subspecies membership for individuals of unknown origin. We used a colorimeter to measure plumage coloration of 374 adult willow flycatchers from 29 locations across their breeding range in 2004 and 2005. We found strong statistical differences among the mean plumage coloration values of the four subspecies; however, while individuals tended to group around their respective subspecies’ mean color value, the dispersion of individuals around such means overlapped. Mean color values for each breeding site of the three western subspecies clustered together, but the eastern subspecies’ color values were dispersed among the other subspecies, rather than distinctly clustered. Additionally, sites along boundaries showed evidence of intergradation and intermediate coloration patterns. We evaluated the predictive power of colorimeter measurements on flycatchers by constructing a canonical discriminant model to predict subspecies origin of migrants passing through the southwestern U.S. Considering only western subspecies, we found that individuals can be assigned with reasonable certainty. Applying the model to migrants sampled along the Colorado River in Mexico and the U.S. suggests different migration patterns for the three western subspecies. We believe that the use of plumage coloration, as measured by electronic devices, can provide a powerful tool to look at ecological questions in a wide range of avian species. The wide range of colors and patterns displayed in the plumage of birds has historically played an important role in elucidating taxonomic groups, particularly in the identification of species, subspecies, and geographic races
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Age, Habitat, and Yearly Variation in the Diet of a Generalist Insectivore, the Southwestern Willow Flycatcher
The Condor, 2008Co-Authors: Scott L. Durst, Tad C. Theimer, Eben H. Paxton, Mark K. SoggeAbstract:ABSTRACT Characterizing avian diet is complex, especially for generalist insectivores, as food resources can vary over space and time, and individuals of different sexes and ages may consume different food. We examined diet of a generalist insectivore, the Southwestern Willow Flycatcher (Empidonax traillii extimus), at Roosevelt Lake in central Arizona from 2000 to 2004, determined from 344 fecal samples. We found that five prey categories accounted for 70% of the proportional abundance in flycatcher diet: Hymenoptera, Diptera, Cicadellidae, Coleoptera, and Formicidae, although the relative amounts of these and other taxa differed significantly among years. We detected no differences in diet between sexes of adults, but adults and nestlings differed, with higher proportions of Hymenoptera in adult samples and more Diptera in nestling samples. Using a subset of samples, we compared flycatcher diet in habitat patches dominated by native cottonwood (Populus fremontii) and willow (Salix gooddingii), exotic sa...
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TERRITORIALITY, SITE FIDELITY, AND SURVIVORSHIP OF WILLOW FLYCATCHERS WINTERING IN COSTA RICA
The Condor, 2006Co-Authors: Thomas J. Koronkiewicz, Mark K. Sogge, Charles Van Riper, Eben H. PaxtonAbstract:Abstract We studied wintering Willow Flycatchers (Empidonax traillii) in two seasonal freshwater wetland habitats in northwestern Costa Rica during five boreal winters, to determine habitat occupancy, overwinter and between-year site and territory fidelity, and the degree to which the sexes maintain and defend winter territories. Both males and females used agonistic displays, song, and other vocalizations to maintain and defend mutually exclusive winter territories. Males were generally more abundant than females, but this varied by site and year. There was no significant difference in male and female territory size, nor any indication of sexual habitat segregation. Similarity in morphology and aggressiveness between the sexes may account for the lack of habitat segregation and the ability of females to maintain territories at wintering sites. Each year, 80%–92% of banded flycatchers that were present in midwinter remained at the site until late winter; of these, 86%–100% of individuals maintained the sa...
Carla Cicero - One of the best experts on this subject based on the ideXlab platform.
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the role of ecologic diversification in sibling speciation of Empidonax flycatchers tyrannidae multigene evidence from mtdna
Molecular Ecology, 2002Co-Authors: Ned K Johnson, Carla CiceroAbstract:: Avian genera characterized by sibling species with distinctive habitat preferences present an evolutionary enigma in view of the more commonplace occurrence of syntopic congeners that differ strikingly in colour and pattern. No existing theory has explained the evolutionary background that led to these differences. Here we propose that great phenotypic similarity among some groups of sibling species limits their coexistence and that clues to their radiation can be seen in patterns of geographical occurrence. To illustrate our thesis we focused on the New World flycatcher genus Empidonax, a group of 15 species notorious for their great phenotypic similarity. Using 3069 base pairs of mitochondrial DNA from four genes, we produced a complete molecular phylogeny that identified four clades, three of which represent close relatives. The fourth clade includes only E. virescens, which apparently has no close living relatives. The majority of species, including many distant relatives, are completely (58.1%) or essentially (6.7%) allopatric in breeding distribution and exhibit striking ecological segregation into distinctive climate-vegetation zones. Even where ranges overlap, occupancy of the same habitat by different species is rare. Phylogenetic and distributional patterns in Empidonax suggest a peripatric model of stepwise colonization and then range expansion of small groups of pioneers during glacial periods into initially enlarging, distinctive habitats destined to be widespread during interglacials. Vicariance is not indicated in the absence of barriers of appropriate age and geographical position. Rapoport's rule that northern species have larger ranges than southern species is strongly supported.
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phylogeny and character evolution in the Empidonax group of tyrant flycatchers aves tyrannidae a test of w e lanyon s hypothesis using mtdna sequences
Molecular Phylogenetics and Evolution, 2002Co-Authors: Carla Cicero, Ned K JohnsonAbstract:Abstract We sequenced mitochondrial DNA from four protein-coding genes for 26 taxa to test W. E. Lanyon's hypothesis of intergeneric relationships and character evolution in the Empidonax group of tyrant flycatchers. Three genera in this group (Empidonax, Contopus, and Sayornis) successfully occupy north temperate habitats for breeding, while the remaining genera (Mitrephanes, Cnemotriccus, Aphanotriccus, Lathrotriccus, and Xenotriccus) are restricted to neotropical latitudes. Lanyon hypothesized two major clades in the group based on differences in syringeal morphology and proposed relationships among genera using a combination of morphologic, behavioral, and allozymic characters. The mtDNA data strongly support Lanyon's division of genera into two clades. In addition, the molecular and nonmolecular data sets agree in uniting Aphanotriccus and Lathrotriccus as sister taxa, with Cnemotriccus as basal to these genera. Species of Aphanotriccus, Lathrotriccus, and Cnemotriccus form a clade that exploits a distinctive nesting niche relative to other members of the Empidonax group. Within the second major clade, mtDNA sequences support a reconstruction based on allozymes that places Contopus and Empidonax as sister taxa. This hypothesis contradicts that of Lanyon, who allied Contopus with Mitrephanes on the basis of similarity in foraging mode. Genera in the Empidonax group are members of a larger assemblage that radiated in South America. Occupancy of temperate habitats by certain genera in this group is coincident with their evolution of migratory behavior and with independent diversification in foraging modes that reduces potential competition in sympatry.
Ross M Lein - One of the best experts on this subject based on the ideXlab platform.
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geographical variation in songs of a suboscine passerine the alder flycatcher Empidonax alnorum
The Wilson Journal of Ornithology, 2013Co-Authors: Scott F. Lovell, Ross M LeinAbstract:Abstract Although there is a large body of literature dealing with the nature of geographic variation in the songs of birds, few studies have examined such variation across the entire range of species of suboscine birds. We measured time and frequency characteristics of songs of Alder Flycatchers (Empidonax alnorum) from six regions spanning almost the entire range of the species, from Alaska to Maine. Both univariate and multivariate analyses demonstrated significant differences in song characteristics among regions, and discriminant function analysis classified 69% of songs to the correct region. We found no relationship between geographic separation and magnitude of difference in songs among regions—songs of birds from some widely-separated regions were more similar than they were to songs of birds from neighboring regions. We argue that these regional differences have a genetic basis, but the pattern of variation does not appear to be consistent with a simple “isolation by distance” model. The variati...
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song variation in buff breasted flycatchers Empidonax fulvifrons
The Wilson Journal of Ornithology, 2008Co-Authors: Ross M LeinAbstract:Abstract I examined song variation within and among 23 individual Buff-breasted Flycatchers (Empidonax fulvifrons) recorded in the Chiricahua and Huachuca mountains of Arizona in 1999. I recorded two distinct song types from each individual during intense pre-dawn singing. I used both spectrographic cross correlation (SPCC) of entire songs and discriminant function analysis (DFA) of temporal and frequency measurements to examine whether songs were individually distinctive, and whether songs differed between the two localities. Similarity values of pairs of songs from SPCC were significantly greater for within-male than for between-male comparisons for both song types. Mean similarity values for the two song types did not overlap between these comparison categories. Similarity values between songs of pairs of males from the same mountain range were not greater than for comparisons between pairs of males from different ranges. All temporal and frequency measures for both song types varied significantly more...
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neighbor stranger discrimination by song in a suboscine bird the alder flycatcher Empidonax alnorum
Behavioral Ecology, 2004Co-Authors: Scott F. Lovell, Ross M LeinAbstract:Bird song and its functions have been studied extensively for more than 50 years, but almost entirely in oscine passerines. Few studies have investigated any aspect of song in suboscine passerines. This is significant because song development and the extent of individual variation in song differs greatly between these groups. Learning and auditory feedback play major roles in song development in all oscines studied, but apparently no part in song ontogeny in suboscines. The ability of territorial oscine males to discriminate between songs of neighbors and strangers has received considerable attention, but this phenomenon is virtually unstudied in suboscines. We tested whether a suboscine bird, the alder flycatcher (Empidonax alnorum), was able to discriminate between songs of neighbors and strangers despite limited individual variation in song. We performed playback experiments to measure responses of males to songs of neighbors and strangers broadcast from the territory boundary shared by the subject and the neighbor. Subjects responded more aggressively to songs of strangers than to songs of neighbors. These results further our understanding of the evolution of song and its functions in suboscines by demonstrating that, similar to their oscine relatives, they can discriminate between the songs of neighbors and strangers. Copyright 2004.