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The Ecology of Song Improvisation as Illustrated by North American Sedge Wrens
Abstract
Can the diverse styles of song development in songbirds be understood in an evolutionary context? Are song imitation and song improvisation strategies that evolved in identifiable ecological circumstances? Differences among Cistothorus wrens suggested that song imitation was used in stable, resident populations by Marsh Wrens (Cistothorus palustris), but that song improvisation evolved in the more nomadic populations of North American Sedge Wrens (C. platensis). Toward understanding this seemingly unique strategy of improvisation by North American Sedge Wrens, we reexamined song development in the laboratory and singing behavior and population movements among free-ranging males. Nestling Sedge Wrens were collected in North Dakota and during their first year of life tutored with 10 Sedge Wren song types; throughout the experiment, males were in adjacent cages and could both hear and see each other. Songs of the laboratory birds were not close imitations of songs from the training tape or immediate neighbors; rather, songs were either improvised (different from but most likely derived from training songs) or invented (no similarity to other songs in their environment). In nature, males at a Nebraska site also had unique song repertoires, a pattern that is consistent with the improvisational mode of song development. Our field surveys also verified that Sedge Wren populations are highly mobile, arriving at or departing from breeding sites at seemingly odd times of the summer breeding season. These data, together with evidence of song imitation among sedentary populations of Sedge Wrens in Central and South America, reinforce the idea that song improvisation among North American Sedge Wrens is a developmental strategy. Because songs are improvised, each male is unique, but songs do not vary geographically; hence, it seems likely that males and females can communicate with one another no matter where they find themselves in the geographic range of the species.
... They typically make multiple nests on their breeding territories, some of which are decoy nests (much like congeneric Cistothorus palustris L.[Marsh Wren]), and one nest, which a female chooses to line with feathers and lay eggs (Burns 1982). Their breeding season is extended, No. 46 2 with birds arriving at higher latitude breeding sites in May and lower latitude breeding sites in August and September (Kroodsma et al. 1999). This difference in arrival times between high latitude and lower latitude areas suggests that Sedge Wrens are itinerant breeders, which breed (or attempt to breed) at higher latitudes and then attempt to do so again later at lower latitudes (Herkert et al. 2020, Kroodsma et al. 1999. ...
... Their breeding season is extended, No. 46 2 with birds arriving at higher latitude breeding sites in May and lower latitude breeding sites in August and September (Kroodsma et al. 1999). This difference in arrival times between high latitude and lower latitude areas suggests that Sedge Wrens are itinerant breeders, which breed (or attempt to breed) at higher latitudes and then attempt to do so again later at lower latitudes (Herkert et al. 2020, Kroodsma et al. 1999. However, compared to their well-studied vocal repertoire (Kroodsma et al. 1999), relatively little is known about their breeding biology and dispersal behavior (Herkert et al. 2020). ...
... This difference in arrival times between high latitude and lower latitude areas suggests that Sedge Wrens are itinerant breeders, which breed (or attempt to breed) at higher latitudes and then attempt to do so again later at lower latitudes (Herkert et al. 2020, Kroodsma et al. 1999. However, compared to their well-studied vocal repertoire (Kroodsma et al. 1999), relatively little is known about their breeding biology and dispersal behavior (Herkert et al. 2020). ...
Cistothorus platensis (Naumann) (Sedge Wren) are highly specialized songbirds typically associated with grasslands, wet meadows, and the fringes of marshes. In New York State, where they are listed as a threatened species, Sedge Wrens breed in low numbers far from coastal urban areas. Nevertheless, from August–October 2020, we documented breeding by three pairs of Sedge Wrens at a reclaimed urban landfill in New York City, within Freshkills Park on Staten Island’s west shore. The birds were observed to have fledged at least three young and remained on-site until at least 11 October 2020. This nesting represents the first successful breeding by Sedge Wrens in New York City since 1960 and shows that this species may persist, even in highly urbanized areas, if suitable habitats are retained or created.
... This is a rare strategy among birds, suggested for only a few species in North America (Bedell 1996, Rohwer et al. 2009, Robbins 2015, with generally incomplete documentation based largely on changing regional abundances throughout the breeding season (e.g., Rohwer et al. 2012). The general pattern for these species is a first nesting attempt in the northern part of the breeding range, followed by movement to more southern portions of the breeding range, with arrival in mid-summer, for a second breeding attempt (Bedell 1996, Kroodsma et al. 1999, Rohwer et al. 2009, 2012, Robbins 2015. Much of the evidence for dual breeding in these species (e.g., Sedge Wrens, Cistothorus platensis, and Marsh Wrens, C. palustris) comes from the absence of occurrence records from areas in the southern portion of the breeding range early in the breeding season followed by arrival in these areas later in the breeding season (Bedell 1996, Robbins 2015. ...
... If documented, a south-then-north dual breeding pattern by Blue Grosbeaks would be the first documentation of such a breeding strategy in North America. Dual breeders in central North America, such as Cistothorus wrens, generally follow a north-then-south strategy, with the first brood in the northern and the second in the southern portion of their ranges (Bedell 1996, Kroodsma et al. 1999, Robbins 2015. This strategy may allow birds to opportunistically occupy ephemeral or limited habitat as it becomes available (Bedell 1996, Kroodsma et al. 1999, Robbins 2015. ...
... Dual breeders in central North America, such as Cistothorus wrens, generally follow a north-then-south strategy, with the first brood in the northern and the second in the southern portion of their ranges (Bedell 1996, Kroodsma et al. 1999, Robbins 2015. This strategy may allow birds to opportunistically occupy ephemeral or limited habitat as it becomes available (Bedell 1996, Kroodsma et al. 1999, Robbins 2015. Several dual breeding birds in western North America also follow this general pattern, although these species appear to capitalize on the flush of resources associated with mid-summer monsoons in southwestern North America (Rohwer et al. 2009(Rohwer et al. , 2012. ...
en Anecdotal observations of mid-summer arrival of Blue Grosbeaks (Passerina caerulea) in South Dakota, in the northern portion of their breeding range, suggest that this species may show a pattern of arrival at the northern breeding grounds that differs from that of other species of migrant birds. We assessed this possibility using three different approaches: (1) data mining from a citizen-science database for South Dakota bird observations, (2) citizen-science roadside surveys in South Dakota in 2019 and 2020, and (3) analyses of temporal occurrence patterns from eBird data for the southern and northern portions of the breeding range. Observations of Blue Grosbeaks from eastern and central, but not western, South Dakota peaked from late June through early August, a pattern of later arrival than other species of migrant birds occupying similar habitats. Results of citizen-science roadside surveys revealed that 57 (2020) to 76% (2019) of the breeding population of Blue Grosbeaks in eastern and central South Dakota arrived after mid-June. Finally, eBird data revealed that Blue Grosbeak occurrence decreased from May to mid-June through August in the southern portion of their breeding range (Texas and Oklahoma), but increased from mid-June through early August in the northern portion of their range in South Dakota. Mid-summer arrival phenology in South Dakota and different temporal occurrence patterns in the northern and southern portions of their breeding range are consistent with a hypothesis of dual breeding for a portion of the Blue Grosbeak population in central North America, with a first brood in the southern and a second in the northern part of their breeding range. However, other possible explanations for these temporal differences in occurrence patterns, such as wandering birds that failed to acquire breeding territories in the southern portion of the range, have not yet been conclusively ruled out. If a dual breeding strategy is confirmed, this would represent the first documentation of a south-then-north pattern for dual breeding in the New World.
RESUMEN
es Llegada a mediados del verano de Passerina caerulea a la extensión norte de su área de reproducción: ¿evidencia de reproducción dual?
Observaciones anecdóticas de la llegada a mediados del verano del picogrueso azul (Passerina caerulea) a Dakota del Sur, en la parte norte de su área de reproducción, sugieren que esta especie puede mostrar un patrón de llegada a los criaderos del norte que difiere del de otras especies de aves migratorias. Evaluamos esta posibilidad utilizando tres enfoques diferentes: (1) extracción de datos de una base de datos de ciencia ciudadana para las observaciones de aves de Dakota del Sur, (2) encuestas de ciencia ciudadana al borde de la carretera en Dakota del Sur en 2019 y 2020, y (3) análisis de ocurrencia temporal entre patrones de datos de eBird para las porciones sur y norte del área de reproducción. Las observaciones de P. caerulea de Dakota del Sur oriental y central, pero no occidental, alcanzaron su punto máximo desde finales de junio hasta principios de agosto, un patrón de llegada más tardía que otras especies de aves migratorias que ocupan hábitats similares. Los resultados de las encuestas de ciencia ciudadana en las carreteras revelaron que del 57% (2020) al 76% (2019) de la población reproductora de P. caerulea en el este y centro de Dakota del Sur llegó después de mediados de junio. Finalmente, los datos de eBird revelaron que la ocurrencia de P. caerulea disminuyó desde mayo hasta mediados de junio hasta agosto en la parte sur de su área de reproducción (Texas y Oklahoma), pero aumentó desde mediados de junio hasta principios de agosto en la parte norte de su área de distribución en Dakota del Sur. La fenología de llegada a mediados del verano en Dakota del Sur y los diferentes patrones de ocurrencia temporal en las porciones norte y sur de su área de reproducción son consistentes con una hipótesis de reproducción dual para una porción de la población del picogrueso azul en el centro de América del Norte, con una primera cría en el sur y un segundo en la parte norte de su área de reproducción. Sin embargo, aún no se han descartado de manera concluyente otras posibles explicaciones para estas diferencias temporales en los patrones de ocurrencia, como las aves errantes que no lograron adquirir territorios de reproducción en la parte sur del área de distribución. Si se confirma una estrategia de reproducción dual, esto representaría la primera documentación de un patrón sur-luego-norte para la reproducción dual en el Nuevo Mundo.
... palustris) and Sedge Wrens (C. platensis) is high, for example, and repertoire sizes are relatively large, too, numbering well over 100 songs per male for both Sedge Wrens and western Marsh Wrens (Verner 1976, Kroodsma 1977, Kroodsma and Verner 1978, Kroodsma, Liu et al. 1999. The trend among Marsh Wren populations is also consistent with this proposed relationship (Kroodsma and Verner 1987). ...
... The second idea relates the style of song development to population stability. Males in sedentary or site-faithful populations of both species tend to imitate each other, whereas males of the less site-faithful, North American populations of the Sedge Wren largely improvise their songs (Kroodsma and Verner 1978, Kroodsma, Liu et al. 1999, Kroodsma, Sánchez et al. 1999. ...
... First, the repertoire size of the Mérida Wren is exceptionally small, averaging about 25 songs per male. In contrast, Sedge Wren males in Costa Rica and North America typically have hundreds of song types in their repertoires (range for seven males, 85 to 330, Kroodsma and Verner 1978, Kroodsma, Liu et al. 1999, Kroodsma, Sánchez et al. 1999. Marsh Wren repertoires are also large, ranging from estimates of 109 to 211 (median 150) for four populations of western North America, down to estimates of 33 to 63 (median 48) in five populations of eastern North America (Kroodsma and Verner 1997). ...
Evidence from two Cistothorus wrens (C. palustris, C. platensis) has suggested that repertoire size increases with population density and that song imitators are more likely to be site faithful than are song improvisers. We tested these two ideas on a third species, C. meridae, an endemic to the Venezuelan Andes. Of the three Cistothorus wrens, song repertoire sizes of male Mérida Wrens are the smallest, ranging from 18 to 27 song types per male; Mérida Wrens are also most likely to repeat each type several times before switching to a new type. Density of Mérida Wrens was also lowest, from 0.4 to 2.0 territories per 10 ha. These wrens are highly site faithful, with marked microgeographic song variation. Female Mérida Wrens also sing. Overall, data from the Mérida Wren support the ideas that, among Cistothorus wrens, song repertoire sizes increase with population density and site faithfulness promotes song imitation.
Variación en el Canto en Cistothorus, con Énfasis en C. meridae
Resumen. La evidencia proveniente de dos especies del género Cistothorus (C. palustris, C. platensis) sugiere que el tamaño del repertorio aumenta con la densidad poblacional y que los imitadores de cantos tienen una mayor probabilidad de ser territoriales que los que improvisan. Estas dos ideas fueron probadas en una tercera especie endémica de los Andes venezolanos, C. meridae. El tamaño del repertorio del canto de esta especie, con 18 a 27 tipos de canto por macho, es el más pequeño de estas tres especies. C. meridae también tiene una mayor probabilidad de repetir cada tipo de canto varias veces antes de cambiar a un tipo nuevo. La densidad de C. meridae también fue la menor, con 0.4 a 2.0 territorios por cada 10 hectáreas. C. meridae es muy territorial, con una marcada variación microgeográfica en las cantos. Las hembras de esta especie también cantan. En resumen, estos datos apoyan las ideas de que en el género Cistothorus, el tamaño del repertorio del canto aumenta con la densidad poblacional y que la territorialidad promueve la imitación de cantos.
... There are, however, some exceptions that can shed additional light on our understanding of latitudinal differences in song structure and singing behavior. For example, it has been suggested that differences in residency and neighbor stability between north temperate and tropical-tosouth temperate Sedge Wrens (Cistothorus platensis) can select for different song development strategies, which in turn affects song sharing between neighbors (Kroodsma et al. 1999). The House Wren (Troglodytes aedon) is another exceptional species with an extremely broad distribution that is ideally suited to detailed investigation of geographic variation in song, but no systematic studies of tropical-south temperate populations have been conducted to date. ...
... In contrast, populations in the south-temperate zone are sedentary, social polygyny is rare with only moderate rates of extra-pair fertilizations, and clutch sizes are small (Young 1996;Llambías , 2012Llambías and Fernandéz 2009;Ippi et al. 2012;Llambías et al. 2012Llambías et al. , 2015LaBarbera et al. 2010LaBarbera et al. , 2012. Differences such as these in basic dimensions of life history, mating system and migration patterns are among the traits implicated in differences in song structure and complexity (Catchpole 1987;Read and Weary 1992;MacDougall-Shackleton 1997;Kroodsma et al. 1999;Collins et al. 2009;Irwin et al. 2008). As a result, there is considerable scope for variation in song patterns in House Wren populations across the Americas, and this represents a truly unprecedented opportunity to examine how variable ecology, life history, migration and mating systems influence song. ...
... Fig. 7 in Rendall and Kaluthota 2013) and limited overlap, or sharing, of complete song types between males. The size of these song repertoires in both populations puts them at the very high end of the continuum for song diversity, alongside some other wren species (Sedge Wrens and Marsh Wrens, Cistothorus palustris: Kroodsma and Verner 1978;Kroodsma et al. 1999) and members of the Mimidae (e.g., Brown Thrashers, Toxostoma rufum, and possibly Gray Catbirds, Dumetella carolinensis: Boughey and Thompson 1981;Kroodsma 2005). ...
Studies of birdsong across very broad geographic scales, such as between the north temperate zone and the tropics, provide special opportunities to understand the role of variable ecologies, life histories and mating pressures on song structure and organization. The problem is typically studied through comparative, cross-species analyses because few species have such broad distributions to encompass both regions. The House Wren is an impor- tant exception, having the widest distribution of any native songbird in the Americas, from Canada to Tierra del Fuego. Across this range, they manifest considerable variation in life history, mating systems and migration, but there is no systematic research on corresponding song variation. Here we provide a first detailed characterization of song structure and organization for Southern House Wrens (Troglodytes aedon chilensis) in western Argentina and provide preliminary comparisons to Northern House Wrens. Songs of Southern House Wrens contained two distinct sections: an introduction of broadband noisy, or harmonic, notes followed by a louder terminal section of tonal, frequency-modulated syllables with a mean of seven syllables and three syllable types per song. The syllable repertoire was large (28), mostly shared and used to construct very large song repertoires (up to 170 song types with no evidence of a ceiling), but much smaller repertoires of commonly produced song types (24). Males tended to repeat song types many times before switching (eventual variety) but, at times, sang with immediate variety. Compared to Northern House Wrens, there were differences in the detailed form of some notes and syllables as well as in the relative emphasis of the softer introduction versus louder terminal section of songs. In broader patterns of song construction, organization, delivery, and the size of syllable and song repertoires, the two populations were very similar. These patterns are discussed in light of differences in life history, mating and migration between them.
... Differences in ecology and sexual selection dynamics may explain some of this variation: In song sparrows, females prefer male songs that have been more accurately copied (Nowicki, Searcy, & Peters, 2002) and males that share more songs with close neighbors are more likely to hold a territory across years (Beecher, Campbell, & Nordby, 2000). In contrast, there may be no benefit to song sharing if social dynamics are not stable over time, as may be the case for the seminomadic sedge wren (Cistothorus platens), where males develop songs that do not resemble those of their neighbors (Kroodsma, Liu, Goodwin, & Bedell, 1999). Although these findings provide some insight into the advantages of song learning, its effects on fitness are still poorly understood (Gil & Gahr, 2002;Beecher & Brenowitz, 2005), having received less attention than the neurological mechanisms of birdsong (reviewed in Janik & Slater, 2000;Brainard & Doupe, 2002). ...
... Sedentary marsh wrens (Cistothorus palustris) establish territories that persist for several years and males develop song repertoires similar to those of their neighbors (Kroodsma & Pickert, 1984), whereas the closely related sedge wren (Cistothorus platensis) is seminomadic during the breeding season. As a result, there is no selective benefit to sharing songs with neighbors and instead individuals develop a more generalized song (Kroodsma et al., 1999). ...
This handbook lays out the science behind how animals think, remember, create, calculate, and remember. It provides concise overviews on major areas of study such as animal communication and language, memory and recall, social cognition, social learning and teaching, numerical and quantitative abilities, as well as innovation and problem solving. The chapters also explore more nuanced topics in greater detail, showing how the research was conducted and how it can be used for further study. The authors range from academics working in renowned university departments to those from research institutions and practitioners in zoos. The volume encompasses a wide variety of species, ensuring the breadth of the field is explored.
... Other species that are capable of accurate and detailed copying of complex songs include canaries [73], zebra finches (Taeniopygia guttata) [74] and nightingales (Luscinia megarhynchos) [75]. At the other end of the spectrum, grasshopper sparrows (Ammodramus savannarum) [76], yellow-eyed juncos [77] and some populations of sedge wrens (Cistothorus platensis) [78] need to hear conspecific models in order to develop songs in the normal range, but do not copy the details of any one model. ...
... Cases in which song development is influenced by external models without accurate copying of a particular model can be attributed to a variety of processes, including (i) inaccurate memorization of an external model, (ii) improvization, in which a bird's own song gradually diverges from an accurately memorized model, and (iii) invention, in which a bird creates a new song that obeys conspecific conventions without copying the details of any specific model [49]. Which of these processes predominates can vary between species [49,78]. ...
Songbirds as a whole are considered to be vocal production learners, meaning that they modify the structure of their vocalizations as a result of experience with the vocalizations of others. The more than 4000 species of songbirds, however, vary greatly in crucial features of song development. Variable features include: (i) the normality of the songs of early-deafened birds, reflecting the importance of innate motor programmes in song development; (ii) the normality of the songs of isolation-reared birds, reflecting the combined importance of innate auditory templates and motor programmes; (iii) the degree of selectivity in choice of external models; (iv) the accuracy of copying from external models; and (v) whether or not learning from external models continues into adulthood. We suggest that because of this variability, some songbird species, specifically those that are able to develop songs in the normal range without exposure to external models, can be classified as limited vocal learners. Those species that require exposure to external models to develop songs in the normal range can be considered complex vocal learners.
This article is part of the theme issue ‘Vocal learning in animals and humans’.
... Support for this relationship among the Cistothorus wrens comes largely from the uniqueness of the Sedge Wren (C. platensis) in North America (Kroodsma et al. 1999a). Breeding site fidelity there is low, and males improvise their large song repertoires, as if a repertoire of generalized rather than site-specific songs were important to communicate with whatever other male and female wrens were encountered within and between seasons. ...
... These Falkland Island data, with matching, learned song types among neighboring resident males, provide additional support for the uniqueness of the North American Sedge Wren populations. Apparently only in the north temperate zone are populations of this species unpredictable and seminomadic, and apparently only there do males largely improvise their large repertoires of song types (Kroodsma et al. 1999a). Elsewhere, in Costa Rica, Brazil, and the Falkland Islands, ranging from the tropics to the extreme south-temperate zone, birds are sedentary or site-faithful and males imitate songs and, at least in Brazil, can countersing with matching song types, much like sedentary Marsh Wrens do so intensely in western North America (Verner 1976). ...
Among songbirds, does reduced fidelity to a breeding site lead to vocal improvisation? Data for Cistothorus wrens suggest it does, because North American Sedge Wrens (C. platensis) have low breeding-site fidelity and improvise their large song repertoires, but sedentary or site-faithful populations of this and other Cistothorus species in the Neotropics and North America all imitate. We attempted to falsify this hypothesis by studying extreme south-temperate zone populations of Sedge Wrens in the Falkland Islands. We banded and recorded males on Kidney Island and Carcass Island, and then compared song matching among males both within and between islands. Birds on those islands were highly site-faithful from one breeding season to the next. Song repertoires were large, up to 400 in one bird, and songs of birds within an island were more similar to each other than to songs on the other island, showing that these birds do imitate. These results further support the idea that site fidelity promotes imitation of neighbors, and continue to highlight the unique correlation between reduced site-fidelity and song improvisation in the North American Sedge Wren.
... For example, it has been proposed that the pressures of sexual selection on song might often be greater for migratory birds in the north temperate zone compared to sedentary birds in the tropics because of the relatively short breeding season in the former, which provides only a limited time window in which to compete for territories and find mates (Catchpole 1987 (Young 1996;Llambías 2009Llambías , 2012Llambías & Fernandéz 2009;Ippi et al. 2012;Llambías et al. 2012Llambías et al. , 2015LaBarbera et al. 2010LaBarbera et al. , 2012. Differences such as these in basic dimensions of life history, mating system and migration patterns are among the traits implicated in differences in song structure and complexity (Catchpole 1987;Read & Weary 1992;MacDougall-Shackleton 1997;Kroodsma et al. 1999;Collins et al. 2009;Irwin et al. 2008). As a result, there is considerable scope for variation in song patterns in House Wren populations across the Americas, and this represents a truly unprecedented opportunity to examine how variable ecology, life history, migration and mating systems influence song. ...
... temperate populations of closely related Sedge Wrens, while sedentary, populations of Sedge Wrens in the tropical-south temperate zone are proposed to learn their songs in more canonical fashion from adjacent neighbors(Kroodsma et al. 1999;Kroodsma 2005). This pattern points to an interesting possible difference in how the selective forces on song learning and repertoire size might differ in migratory and sedentary populations between Sedge Wrens and House Wrens.That many of the features of song organization and singing style in SHOWR were so similar to those in NHOWR is a bit unexpected in light of the many documented differences in life history and mating system between them. ...
This thesis focused on an austral population of House Wrens breeding in the south-temperate zone in Mendoza, Argentina. A description of song organization and complexity is provided for males in this population, and comparisons are made to song patterns reported for House Wrens in the north-temperate zone. Song patterns were remarkably similar between the two zones. Further analyses revealed significant correlations between metrics of song complexity and breeding success in the focal population of House Wrens in Argentina. The latter findings suggest that pressures of sexual selection have affected song evolution in this austral population of House Wrens in ways similar to reported sexually selected effects on song for north-temperate songbird species. This outcome is not well accommodated by current theory. These findings underscore how traditional theory concerning the evolution of song could be expanded through additional studies on South American populations and species, which have been understudied to date.
... Secondly, age depended acoustic changes are probably related to the birds' ability for vocal learning. Birds can memorize songs of conspecific individuals after fledging (Hultsch and Kopp 1989), in their first year of breeding (Payne 1983;Kroodsma et al. 1999), in wintering sites or during migratory stops (Dowsett-Lemaire 1979;Catchpole and Slater 2008). One key mediating factor for changes in song repertoires by dropping and adding song types between seasons might be the advantage of sharing song patterns among neighbours and/or within populations (review in Kipper and Kiefer 2010). ...
... The song sharing phenomenon is widespread among many species of songbirds and it plays an important role in communication system and species' social interactions (Payne et al. 1988;Vehrencamp 2001;Demko et al. 2016). Neighbouring males can share all or most of the song types (Schroeder and Wiley 1983;Payne and Payne 1985), or intermediate levels of repertoire overlap (McGregor and Krebs 1989;Lemon et al. 1994), while full songtype sharing is observed quite seldom (Ewert and Kroodsma 1994;Kroodsma et al. 1999). Inter-and intraspecific variation in the level of song-type sharing is attributed to different learning strategies, timing and duration of the critical learning period, seasonal migration and dispersal patterns (Slater 1989). ...
In many oscine passerines males’ songs, the repertoire size increases with age. At the same time it often remains unknown when and where males learn new songs. To infer the Whinchat Saxicola rubetra song learning strategy, we described and catalogued song-type repertoire, revealed age differences and examined song sharing strategies among neighbouring and distant males. We recorded song vocalizations of 40 males in a limited (104 ha) study plot during four years. Whinchats produce short and discrete songs with clear intersong pauses. In total 45 song types were allocated, the individual repertoire size averaged 23.5 ± 7.6 song types (range 9–34 song types). The males’ age significantly influenced the song-type repertoire size. The second calendar year (first breeding) males had a lower repertoire size than the older males. The majority of song types were shared by less than half of males in our sample. The Jaccard similarity indexes varied from 0.5 to 0.7. We could not find a relationship between males’ song sharing and geographic distances between their nests. We assume that Whinchat males learned new songs in the local population before territory establishment.
... Our finding of a positive relationship between song similarity and distance in some song traits instead of the most widespread negative relationship may be explained by the biology of the study species. Collared flycatchers are long-distance migrants and the population turnover is high (based on our ringing records 18% ± 3% of the breeding birds bred again in the next year regarding the consecutive study years), so the benefit of singing similarly to their neighbors may be low, as was suggested previously for other migratory birds (Kroodsma et al. 1999;Nelson et al. 2001;Yoon et al. 2013). Collared flycatchers usually sing for a few weeks at the beginning of the breeding season, when neighbors may change on a daily basis, so song similarity with these neighbors may have little advantage in promoting communication. ...
The position occupied in social networks influences the success of individuals in many animal species. However, the associations between bird song (an important means of communication) and the relative position in social networks remained understudied. Such associations are expected because neighbors can learn song elements from each other or change their songs due to competition, and also because song can be related to other individual traits determining social network positions. We investigated these phenomena in males of the collared flycatcher (Ficedula albicollis), a passerine with complex songs and intense territorial interactions. Relying on 19 years of song recordings, we used multiple traits reflecting the spectral and temporal characteristics and complexity of songs, as well as syllable composition, to investigate if similarity in song is associated with the position in neighbor networks. We also examined whether birds settle down in an age‐dependent manner (as age is linked to individual quality) and whether the nonrandom spatial distribution of song is affected by the proportion of immigrants, young birds, or the number of displaying males. We found that the minimum frequency and the repertoire size of neighbors differed, but this pattern was not shaped by the investigated predictors. Therefore, our results highlight the need to study communication traits and social environment together. The fact that neighboring males tend to sing differently with respect to some song traits suggests that songs can be flexibly adjusted based on the performance of conspecifics.
... We observed large repertoires of song elements per individual, and we suspect that highly variable songs result from the possibility of many different combinations of syllables and element types, similar to the closely related species, the saffron finch, Sicalis flaveola (Benítez Saldívar & Massoni, 2018). Song variation may also arise stochastically due to recombination of pre-existing song elements (Slabbekoorn et al., 2003), or from copying errors during song learning (Gammon et al., 2005) or improvisation (Johnson, 2006;Kroodsma et al., 1999). This variability often follows a pattern of isolation by distance, where geographically close individuals share more similar songs than distant ones (e.g. ...
The likelihood of hybridization after secondary contact is reduced when assortative mating is strong and fitness of hybrids is low; thus, maintaining reproductive isolation. To this end, signals that convey population identity may enhance recognition and reduce hybridization by promoting assortative mating. Here, we studied visual and acoustic signals, plumage colour and song, that commonly mediate species recognition in birds to evaluate their role in reproductive isolation in a recently diverged clade of Neotropical birds. Subspecies of the variable seedeater, Sporophila corvina, that differ dramatically in plumage colour have established secondary contact at two independent contact zones in Costa Rica and Panama. We first evaluated divergence in song in allopatric populations close to the most recent contact zone (Costa Rica), where the two subspecies do not hybridize, and found significant differences in song structure and composition of song elements between subspecies. Then, we used an experimental approach to measure a territorial male’s aggressive response to visual and acoustic signals, as a proxy of the role of divergent secondary sexual traits in reproductive isolation. These playback experiments did not show clear effects of divergent colour or song on aggressive response: we found no effect of plumage coloration or song in one subspecies and males of the other subspecies were more aggressive towards homotypic songs but, unexpectedly, also more aggressive towards to heterotypic plumages. Separately, we also characterized the song structure of hybrid individuals from the Panamanian contact zone to evaluate how songs covary given evidence for gene flow. These hybrid individuals sang songs of different element composition than allopatric subspecies but did not differ in most acoustic characteristics. Overall, our experiments suggest that reproductive isolation based on secondary sexual signals is weak in this group, and after secondary contact, the breeding phenology may synchronize and divergent acoustic signals may homogenize, facilitating further hybridization.
... This variation in inter-and intraspecific song-type sharing can be attributed mainly to differences in song-learning strategies, critical-period timing and duration, and dispersal patterns of juveniles (Koetz et al. 2007, Slater 1989, Wilson et al. 2000. Differences in imitation learning and seasonal migration also may affect song-type sharing within or among species (Handley and Nelson 2005, Kroodsma 1974, Kroodsma et al. 1999, Nelson et al. 1995. ...
... This might be due to song uniformity throughout the breeding range, with songs of the same characteristics recurring frequently in distant populations, as described for passerines with simple vocalization (Bryan et al. 1987;Kroodsma et al. 1999a). Lack of clear geographic patterns may also result from extensive individual variation when each male has unique vocalization, either rich repertoire of many song types (Kroodsma et al. 1999b) or single individually specific song types (e.g., Tsipoura and Morton 1988;Janes and Ryker 2016). ...
Decades of research on geographic variation of birdsong have provided evidence that passerine vocalization often diverges among populations. We asked whether even songs so simple that they superficially resemble stridulating insects vary geographically. We focused on two closely related species of the genus Locustella, the River Warbler (L. fluviatilis) and the Grasshopper Warbler (L. naevia). At four Central European localities separated by 85–380 km, we recorded 62 River Warbler males, and at three of these sites, we also recorded 32 coexisting Grasshopper Warbler males. We hypothesized to observe differences among geographically distant populations in both species. However, only the song of River Warbler diverged among the localities in structural and quantitative parameters, especially in the number, frequency and position of high-amplitude notes within the repeated syllables. Discriminant analysis successfully classified 80% of all River Warbler males to their respective population, in agreement with our subjective classification of songs into several categories. In contrast, the populations of Grasshopper Warbler at the same spatial scale could not be differentiated either by visual inspection or by any of the measured song characteristics. Further comparison with spectrograms available from the European range of both species supported these patterns also on a larger geographical scale, with additional distinct River Warbler song types observed out of our study region, but similarly looking Grasshopper Warbler song types distributed across the continent. Different patterns of song geographic variation in the two coexisting, closely related species highlight species-specific traits that contribute to song divergence and imply the great diversity in singing behaviour among songbirds.
... Notes.-Formerly considered conspecific with C. platensis, but separated, following Remsen et al. (2021), based on differences in vocalizations and other behavior (Kroodsma 1999a(Kroodsma ,b, 2001(Kroodsma , 2002Nyári 2014, Boesman 2016), as well as mitochondrial genetic data that indicate that platensis forms a clade with two restricted range species in the high Andes of Venezuela and Colombia, C. meridae Hellmayr, 1907 [Merida Wren] andC. apolinari Chapman, 1914 [Apolinar's Wren], to the exclusion of stellaris (Robbins and Nyári 2014). ...
... A corruíra-do-campo Cistothorus platensis (Latham, 1790) é um trogloditídeo amplamente distribuído nas Américas, habitando regiões como os Andes, a Patagônia, os campos do Rio da Prata e o Cerrado (Del Hoyo et al., 2005;Llambías et al., 2018). Esta espécie de ave insetívora Artigo e campestre, que não se adapta a áreas modificadas (Sick, 1997;Vickery et al., 1999;Tubelis & Cavalcanti, 2001), teve asptectos de sua biologia investigados principalmente na América do Norte (Burns, 1982;Kroodsma et al., 1999a;Del Hoyo et al., 2005;Kirsch, 2007) e Argentina (Llambías et al., 2018). ...
RESUMO A corruíra-do-campo Cistothorus platensis (Latham, 1790) apresenta ampla distribuição geográfica, ocorrendo ao longo de todo o continente americano. Informações sobre sua biologia têm sido obtidas principalmente em regiões temperadas, e o conhecimento sobre suas áreas de vida em campos tropicais é inexistente. O objetivo deste trabalho foi estudar as áreas de vida de C. platensis no Parque Nacional da Chapada dos Veadeiros, Cerrado do Brasil central. Quatorze machos foram anilhados em um campo sujo e cinco deles puderam ser acompanhados continuamente entre fevereiro e dezembro de 2008. O tamanho médio das áreas de vida (n = 5) foi de 6,10 ± 2,09 ha (Mínimo Polígono Convexo) e 4,57 ± 1,92 ha (Kernel 95%) e variaram significativamente entre as estações estudadas. As áreas de vida foram maiores na estação seca (período não-reprodutivo) do que na estação chuvosa (que abrangeu os períodos reprodutivo e não-reprodutivo). Houve baixa sobreposição entre áreas de machos vizinhos. As aves estudadas não estabeleceram áreas de vida em trechos de campo recentemente queimados. Alguns indivíduos foram registrados durante todo o período do estudo, sendo assim considerados residentes. Entretanto, nove dos 14 machos não persistiram no local. Não houve evidência de poliginia, uma vez que somente casais ou aves solitárias foram registradas. Este estudo indica que C. platensis habitando campos naturais no Cerrado são monogâmicos e têm áreas de vida maiores do que em regiões temperadas.
... Intermediate levels of repertoire overlap have been found in species such as the Great Tit (Parus major; McGregor and Krebs 1989) and American Redstart (Setophaga ruticilla; Lemon et al. 1994). Whole song-type sharing, although present, is rare (Ͻ 5%) in migratory populations of Eastern Towhees (Pipilo erythrophthalmus; Ew- and Kroodsma 1994) and Sedge Wrens (Cistothorus platensis; Kroodsma et al. 1999). ...
The extent and spatial pattern of song-type sharing among neighboring males in one subspecies of Song Sparrow, Melospiza melodia cooperi, were examined in two San Diego County populations. Repertoire size averaged 9.6 song types per male (range 7 to 14). Song-type sharing was greatest between neighbors and declined with distance between territories. Adjacent neighbors shared an average of 22% of their song types. Variation in the amount of sharing between adjacent territory owners was high, ranging from 0% to 86% repertoire overlap. Results are consistent with the expected pattern produced by age-restricted learners that attempt to establish territories near tutors. The probability of a male surviving and remaining on his territory through the breeding and nonbreeding season increased as the fraction of song types shared with adjacent neighbors increased. The amount of song-type sharing may therefore be an indicator of a male's competitive ability to obtain a preferred territory near his tutors, or it may determine a male's effectiveness in using shared and unshared song types to communicate aggressive intentions.
... 1.1a). During the breeding season, northern Sedge Wrens are highly nomadic with little site delity, apparently producing rst broods and second broods in different areas of their breeding range (Bedell 1996;Kroodsma et al. 1999b;Hobson and Robbins 2009; but see Burns 1982). In contrast, Sedge Wrens in Central and South America (southern Sedge Wrens hereafter) are year-round residents (Brewer 2001;Kroodsma and Brewer 2005). ...
The Nearctic and the Neotropic differ in several abiotic and biotic features that have profound implications in avian ecology. Several of these variables are predicted to affect social mating systems. The Sedge Wren (Cistothorus platensis) and the House Wren (Troglodytes aedon) are distributed from Canada to Cape Horn and are ideal species to evaluate the differences in social mating systems between hemispheres. We compared the social mating system, male contribution to feeding nestlings, clutch sizes, and number of nestlings fledged in north temperate and south temperate wrens using original data gathered in three study sites and published data from four additional sites. In the north, polygyny rates were higher and clutch sizes were larger than in the south. Furthermore, in the north polygyny was achieved when a male attracted an additional female to his territory while in the south, polygyny occurred when a monogamous male replaced a neighboring male and bred with the resident female. We did not find a clear association between parental care patterns and social mating system in the north. Although northern wrens had similar rates of social polygyny, northern Sedge Wren males contributed less to feeding nestlings than northern House Wrens males. Our results suggest social divergence between hemispheres and social convergence within hemispheres, probably caused by variation in underlying common factors. We suggest that differences in polygyny rates between hemispheres can be caused by a combination of migratory behavior and life-history strategies that affect the control and manipulation that males can exert over female reproduction.
... Along with species specific features of song imprinting and subsequent correction in the course of learning, of major significance is also the type of spa tial behavior characteristic of a given species, prima rily the phenomena of philopatry and nesting site fidelity. Both these factors may have an effect on the processes of population and geographic song differen tiation (Kroodsma et al., 1999). ...
Based on recordings, the time-frequency characteristics and repertoire size of the advertising song were studied comparatively in several leaf warblers (Phylloscopus) and reed warblers (Acrocephalus) from mainland and island populations. No significant variations in repertoire size were found between mainland and island populations, but clear differences were revealed in the frequency and time parameters of the song between the Sakhalin and continental populations. In all of the species studied, the differences are displayed in a similar way. In the Sakhalin population, the frequency range is wider than in the mainland. Possible reasons for this expansion are discussed: (1) the impoverishment of the species composition of ornithocomplexes, (2) the effect of high air humidity, and (3) the effect of specific characteristics of the vegetation cover.
... It is not clear, however, how the own-song hypothesis accounts for how songbirds recognise conspecific syllables that are improvised (and thus often unique to individual birds; e.g. North American sedge wrens; Kroodsma et al., 1999), how birds that only sing a subset of song syllable types rather than all possible syllable types can recognise conspecific syllables that they themselves do not produce (e.g. zebra finches; Sturdy et al., 1999), or how songbirds can discriminate between sounds that completely different from their own song (such as human speech) and potentially unrecognisable as a song syllable. ...
Humans perceive speech as relatively stable despite acoustic variation caused by vocal tract (VT) differences between speakers. Humans use perceptual 'vocal tract normalisation' (VTN) and other processes to achieve this stability. Similarity in vocal apparatus/acoustics between birds and humans means that birds might also experience VT variation. This has the potential to impede bird communication. No known studies have explicitly examined this, but a number of studies show perceptual stability or 'perceptual constancy' in birds similar to that seen in humans when dealing with VT variation. This review explores similarities between birds and humans and concludes that birds show sufficient evidence of perceptual constancy to warrant further research in this area. Future work should 1) quantify the multiple sources of variation in bird vocalisations, including, but not limited to VT variations, 2) determine whether vocalisations are perniciously disrupted by any of these and 3) investigate how birds reduce variation to maintain perceptual constancy and perceptual efficiency.
... Within protracted bouts of singing, males tended to repeat the same song types many times before switching and, thus, sang with "eventual" rather than "immediate" variety, as originally predicted by cf. Kroodsma et al., 1999). Occasionally, males switched between different song types more abruptly, or toggled back and forth between two song types before converging on one of them, which they then repeated multiple times. ...
Elaborated male displays, such as the complex songs of some songbirds, are thought to have evolved via processes of sexual selection addressing two main functions: attracting mates and repelling rivals. House Wrens (Troglodytes aedon) are a good model species because, while not yet systematically studied, the species’ song is noted for being elaborate and complex. The first step in research was to establish basic patterns of male breeding success under natural conditions. The second step was to provide a detailed characterisation of song organisation and diversity and begin to identify dimensions of song performance and complexity likely relevant in female choice of male partners or in male defence of territories against rivals. The final step involved a broad-scale latitudinal study of song patterns across the Americas testing the relevance of these elements of sexual selection on song performance and complexity in House Wrens.
... The possibility that song is learned from neighbours was tested several times. For example, in the sedentary North American sedge wren (Cistophorus platensis), males learn their songs mainly from their neighbours, but individuals from nomadic populations use improvisations (Kroodsma et al. 1999). Also, Putland et al. (2006) found that Albert's lyrebird (Menura alberti) learns from two separate sources; matching of song dialects among sites suggests that lyrebirds learn songs from the models [Satin bowerbird (Ptilonorhynchus violaceus)], but reduced structural variation in the lyrebird imitations within sites suggests that these song types are also culturally transmitted among lyrebirds. ...
Vocal mimicry in birds is a well-known phenomenon, but in the majority of bird mimic species, its function, variability and accuracy still remain undiscovered. We analysed the song of 23 Icterine warbler (Hippolais icterina) males in České Budějovice (Czech Republic) and identified 52 mimicked species. Our results showed that Icterine warbler males (1) mimicked species that are present in their territories (i.e. passive sampling hypothesis), (2) mimicked alarm calls more frequently than non-alarm calls (i.e. alarm call hypothesis), (3) produced species-specific non-mimetic song that is most similar to the alarm calls of frequently mimicked species (i.e. acoustic similarity hypothesis) and (4) produced mimicry that is not perfect, but still acoustically convincing. These results suggest that Icterine warbler males largely reflect the surrounding acoustic environment in their song, but simultaneously selectively include vocalisations that are similar to their own song as a result of physiological constraints. We further found that (5) songs of neighbours are not more similar compared with more distant males and (6) there is no relationship between genetic and song similarity suggesting that song is learned mainly from heterospecifics.
... Many of the types in a Cassin's vireo, Vireo cassinii, repertoire of 44e60 phrases are uttered rarely; on average the rarest type in a bird's repertoire accounts for 0.07% of sampled songs (Hedley, 2016). Song types are similarly hidden by the singing patterns of other large-repertoire species such as the nightingale, Luscinia megarhynchos (Kipper & Hultsch, 2006), sedge wren, Cistothorus platensis (Kroodsma, Liu, Goodwin, & Bedell, 1999), and bananaquit, Coereba flaveola (Wunderle, Cortes, & Carromero, 1992). ...
Songbirds of a number of species use song repertoires that contain some song types that are uttered only rarely, and are therefore unlikely to be heard by the typical listener. Singing patterns that hide song types are difficult to reconcile with putative repertoire functions that require listeners to evaluate the size or diversity of singers' repertoires. Perhaps in species with repertoires that include rarely used song types, the rare types serve a function that is required only rarely. Based on observations of chestnut-sided warblers, Setophaga pensylvanica, I hypothesized that in this species, rarely used song types are reserved for use in extreme aggressive contexts. I experimentally simulated such a context (a prolonged territorial intrusion by a male competitor) by presenting song playback and a taxidermic mount on chestnut-sided warbler territories. The targeted males were much more likely to use their rare song types during the simulated intrusions than during natural baseline singing. A similar but smaller effect was evident in an analysis of natural singing that compared songs associated with fighting and chasing with songs that were not. Use of rare song types by experimental subjects did not predict their likelihood of attacking the simulated intruder. If this lack of predictive value is not an experimental artefact and extends to natural interactions, it suggests that despite their association with highly aggressive contexts, rarely used song types might not represent the strongest possible signal of aggressive motivation in chestnut-sided warblers. Perhaps use of rare types instead represents the penultimate level in a graded series of aggressive signals that culminates with a signal variant that went undetected in this experiment.
... Thus, even in the breeding season, they have a constantly changing set of neighbours. These sedge wrens show a unique pattern of song learning in tape tutor experiments: they do not imitate tutor songs but rather improvise songs (different but derived from the tutor songs) or invent songs (totally new), all of them normal species songs (Kroodsma, Liu, Goodwin, & Bedell, 1999;Kroodsma & Verner, 1978). Consequently, each bird winds up with a repertoire of unique songs, and two neighbours in the field (who probably will not be neighbours for long) will share no song types. ...
This paper describes a 30-year investigation into the role of social and ecological factors affecting song learning in song sparrows, Melospiza melodia. It addresses the question of why song sparrows learn the songs they do, given that they are exposed to many more songs than they will keep for their final repertoire of 7–11 song types. A young song sparrow moves from his natal area at about 1 month of age, eventually settling in an area where he learns the songs of the resident males and attempts to establish his own territory. Birds that share many songs with their neighbours in their first breeding season (the spring following their hatch summer) survive for more years on territory than birds that do not. Many features of the song-learning process lead to a high level of sharing with first-year neighbours, including preferentially learning the songs of their tutor-neighbours who survive the winter, and learning songs that are shared by several tutors. Social interaction appears to be critical in song learning, but indirect effects (eavesdropping on adults countersinging) seem to be at least as important as direct interaction between the young bird and his tutor-neighbours. Although our evidence suggests that the song-learning strategy of young song sparrows is beneficial to them, a preliminary analysis suggests it may not benefit their tutors.
... [8]), and others are flexible, learning some songs socially and acquiring novel songs by improvisation or invention (i.e. modification of tutor songs, or new songs altogether, respectively [4,9]). The latter is the case in the dark-eyed junco (Junco hyemalis). ...
Social learning enables the adjustment of behaviour to complex social and ecological tasks, and underlies cultural traditions. Understanding when animals use social learning versus other forms of behavioural development can help explain the dynamics of animal culture. The dark-eyed junco (Junco hyemalis) is a songbird with weak cultural song traditions because, in addition to learning songs socially, male juncos also invent or improvise novel songs. We compared songs shared by multiple males (i.e. socially learned) with songs recorded from only one male in the population (many of which should be novel) to gain insight into the advantages of social learning versus invention or improvisation. Song types shared by multiple males were on average of lower performance, on aspects of vocal performance that have been implicated in agonistic communication in several species. This was not explained by cultural selection among socially learned songs (e.g. selective learning) because, for shared song types, song performance did not predict how many males shared them. We discuss why social learning does not maximize song performance in juncos, and suggest that some songbirds may add novel songs to culturally inherited repertoires as a means to acquire higher-quality signals.
... Here, 'improvisation' refers to cases in which the eventually crystallized song is influenced by but does not closely resemble tutor models (this has also been termed 'innovation' by Janik & Slater 2000), and 'invention' refers to cases in which tutor models have little or no influence on learned song. Song development primarily or solely by improvisation or invention appears to be uncommon, but the development of normal repertoires in the absence of exposure to song models (i.e., invention) has been documented in two species (gray catbird Dumetella carolinensis: Kroodsma et al. 1997; sedge warbler Acrocephalus schoenobaenus: Leitner et al. 2002), and two other species improvise much of their repertoires (sedge wren Cistothorus palustris: Kroodsma et al. 1999;American robin Turdus migratorius: Johnson 2006). Recently, the grasshopper sparrow Ammodramus savannarum has also been found to develop both its 'buzz song' and its 'warble song' types by improvisation (Soha et al. 2009). ...
Geographic variation in birdsong and differential responses of territorial males to local and non-local song variants have been documented in a number of songbird species in which males learn their songs through imitation. Here, we investigated geographic song variation and responses to local and non-local song in the grasshopper sparrow (Ammodramus savannarum), a species in which males develop song by improvisation rather than imitation, as a first step toward understanding how the extent and salience of geographic song variation is related to the mode of song development. To describe the geographic variation in song, we compared songs from populations in eastern Maryland and central Ohio, USA, using multiple acoustic analysis techniques. We then conducted a playback experiment in Maryland using local and non-local (Ohio) songs to test how territorial males responded to this geographic variation. We found acoustic differences between songs from the two sites. However, males responded similarly to playback of these songs, suggesting that this geographic variation is not behaviorally salient in a territorial context. Together with previous studies, our results suggest that across species, geographic song variation and the extent to which this variation functions in communication may be correlated with the accuracy with which song models are imitated during song development.
... For traits that have a cultural component, such as learned birdsong, novel traits (e.g. new vocal phenotypes) can also arise from copying errors (Payne, 1996;Podos, 1996), improvisation (Johnson, 2006;Kroodsma, Liu, Goodwin, & Bedell, 1999), or recombination of existing signals (Jenkins & Baker, 1984;Slabbekoorn, Jesse, & Bell, 2003). The persistence of novel vocal traits may be influenced by corresponding shifts in signal context or function; for example, birdsong is important in both maleemale competition and female choice, and shifts in the importance of those selective pressures may significantly influence signal phenotype (Berglund, Bisazza, & Pilastro, 1996;Borgia & Coleman, 2000;Irwin, 2000). ...
Revealing the evolutionary origin of novel traits is a long-standing challenge in evolutionary biology. The dynamics of antipredator signalling and conspecific advertisement provide one framework in which to investigate this phenomenon, because shifts in signal context may lead to new signal functions, novel evolutionary pressures and ultimately novel phenotypes. Several species of fairy-wrens (Maluridae: Malurus) give song-like trills (‘Type II song’) in response to vocalizations of avian predators. Despite this predator context, in some species the trills appear to function as conspecific-directed displays. We investigated two hypotheses for the evolutionary origin of predator-elicited Type II songs: (1) they originated as antipredator signals, then shifted to a display context and subsequently became more elaborate because selection pressures changed; or alternatively (2) they originated as conspecific-directed songs, then shifted to a predator context to exploit an effective communication window. Using predator playbacks and samples of natural dawn chorus recordings, we found that many Malurus species gave trills in response to predators, but only a subset gave unprompted trills during dawn chorus displays, and ancestral state reconstructions suggested that the predator-elicited context evolved first. Additionally, species that used trills more often (in both predator and unsolicited contexts) tended to have longer trills with a faster note rate, suggesting that trills have evolved a higher performance as they became a more important part of the display repertoire. Our results support the hypothesis that trill displays originated through the elaboration of predator context calls and provide an example of a shift in signal context leading to novel signal phenotypes.
... Thus even in the breeding season, they have a constantly changing set of neighbors. These sedge wrens show a unique pattern of song learning in tape tutor experiments: They do not imitate tutor songs but rather improvise songs (different but derived from the tutor songs) or invent songs (totally new), all of them normal species songs (Kroodsma and Verner, 1978;Kroodsma et al., 1999a). Consequently, each bird winds up with a repertoire of unique songs, and two neighbors in the field (who probably will not be neighbors for long) will share no song types. ...
... A larger fraction of individual syllables comprising the repertoires probably facilitates individual recognition (Falls 1982, Beecher et al. 1994), although unique syllables or song types may not be necessary to accomplish individual recognition (Weary and Krebs 1992). Individual syllables could be invented, improvised or learned elsewhere (Marler and Peters 1982, Payne 1996, Kroodsma et al. 1999. Johnson (2006) observed that most of the elements (75-82%) in the repertoires of handreared American Robins were acquired by invention. ...
Song repertoire size and extent of song sharing provide information about social interactions that occur
in songbird species. We recorded the songs of eight male Clay-colored Thrushes (Turdus grayi) in San Jose, Costa Rica, during the 2008 breeding season. We classified 695 songs and 5,032 syllables using visual inspection of spectrograms and spectrogram correlation analysis to measure repertoire size and syllable sharing among a local group of males. Male repertoire size was 10–17 syllable types. Males shared on average 28 6 15% (SD) syllable types from their repertoires with other males, but a larger proportion of syllable types remained unique to particular males. Extent of repertoire sharing and distance between singing males were not related. Presence of shared and individually unique syllables in the repertoires
indicate that imitation, and perhaps improvisation, contribute to development of the song of Clay-colored Thrushes.
... Detailed studies on species with relatively small repertoire size have shown isolation-by-distance patterns of geographic variation in sharing of song types and similarity in structural song characteristics, with the highest similarity among direct neighbours ( Rivera-Gutierrez et al., 2010) or among individuals that are a few territories apart (Lachlan & Slater, 2003). Individuals from other species may have large improvised song repertoires without much geographic structure ( Kroodsma et al., 1999) or may typically sing a single stereotypic song, shared among neighbours, and forming small, geographically distinct, acoustic clusters ( . ...
Many bird species, especially song birds but also for instance some hummingbirds and parrots, have noted dialects. By this we mean that locally a particular song is sung by the majority of the birds, but that neighbouring patches may feature different song types. Behavioural ecologists have been interested in how such dialects come about and how they are maintained for over 45 years. As a result, a great deal is known about different mechanisms at play, such as dispersal, assortative mating and learning of songs, and there are several competing hypotheses to explain the dialect patterns known in nature. There is, however, surprisingly little theoretical work testing these different hypotheses at present. We analyse the simplest kind of model that takes into account the most important biological mechanisms, and in which one may speak of dialects: a model in which there are but two patches, and two song types. It teaches us that a combination of little dispersal and strong assortative mating ensures dialects are maintained. Assuming a simple, linear frequency-dependent learning rule has little effect on the maintenance of dialects. A nonlinear learning rule, however, has dramatic consequences and greatly facilitates dialect maintenance. Adding fitness benefits for singing particular songs in a given patch also has a great impact. Now rare song types may invade and remain in the population.
Unicolored Jays (Aphelocoma unicolor) are little-known social corvids of Mexico and Middle America. Like other birds in the family Corvidae they possess a vocabulary composed of sounds usually referred to as calls rather than songs. Here we provide the first description of this species’ rich vocabulary. We studied vocalizations of color-banded Unicolored Jays in Chiapas, Mexico from January through May of 1987. There they live in cooperatively breeding groups of four to nine birds. We distinguish 697 long-range call variants from our recordings, which probably did not exhaustively sample the range of jay sounds on our study site. The sonograms of the sounds can divided into broad categories with finely graded spectrum-like variation within them, and generally no sharp boundaries between them. Nearly any sonogram in the vocabulary can be connected structurally to any other through a range of intermediates. The jays tended to introduce many new related variations on a call theme in a single calling session, and many of these variants were not recorded again. There is some indication that the jays favored using a few call types in particular behavior contexts, but they used the great majority of them in a range of widely varying settings. The jay groups shared only a minority of their call collections with one another, but many of the unshared calls were rarely recorded and may not have represented typical vocal differences between them. A few commonly used calls did seem to be peculiar to one or a few jay groups. Vocalizations recorded on our study site in 1987 differ notably from those recorded there in 2006, strongly suggesting cultural turnover in the local assortment of calls. Recordings from other A. unicolor populations in southern Mexico show marked geographic variation on a regional scale. We suggest that the tendency of Unicolored Jays to produce series of similar and apparently new calls in spates, geographical variation in calls on scales small and large, and turnover in calls at a single locality may all reflect call learning, call improvisation, and the process of random vocal change known as culture drift. We also describe a variety of the jays’ soft short-range calls, some of them strikingly similar to those in other species of Aphelocoma, and others, including some common ones, not previously known in this genus. Like other Aphelocoma, A. unicolor on our study site had rattle calls (one fast and one slow), and whisper song. The precise similarities between certain calls of A. unicolor and those of its relatives show either a startling degree of fidelity in vocal copying over thousands of generations, or a strong innate tendency to reproduce certain details of their vocabularies.
Acoustic communication plays a critical role in the lives of most species of birds. The focus of this chapter is on the ways that birds produce both nonvocal and vocal sounds. The anatomy of the avian syrinx and how it varies among different taxa of birds is discussed. The mechanism by which the syrinx produces sounds is explained and the types and functions of those sounds (calls and songs) are discussed in detail. Different species of birds vary dramatically in the size of their vocal repertoires, including call and song types, and possible explanations for such variation are provided. Many aspects of the singing behavior of birds are discussed, including the mechanisms by which the central nervous system controls singing behavior and differences between the sexes in those mechanisms, variation within and among species in song structure, the various functions of bird song, intra- and interspecific variation in the size of song repertoires, and the process of song learning. Also discussed are vocal mimicry, duetting, group choruses, and the roles of vocalizations in male cooperative courtship.
The temperate zone model where males sing vigorously to defend seasonal territories and to attract social and extra-pair mates does not apply well to the many tropical birds that defend year-round territories. While tropical birds with seasonal territories often have high song rates that function in intersexual and intrasexual communication, year-round residents tend to have very low song rates presumably because their territory boundaries and neighbors are so well known. It is not well understood why some tropical species have a strong dawn chorus while others do not, or what role the dawn chorus versus daytime song plays in territory defense or mate assessment. Female song, and vigorous territory defense, is more common in tropical than temperate birds. Playback experiments to test the function of duetting in tropical birds have found much variation among species in whether territorial aggression is sex-specific and the extent to which the duetting pair cooperates in defense. Tropical birds also feature greater female plumage ornamentation, but relatively few studies have experimentally tested what role this plays in communication, mate choice, or territory defense.
Young songbirds draw the source material for their learned songs from parents, peers, and unrelated adults, as well as from innovation. These learned songs are used for intraspecific communication, and have well-documented roles for such functions as territory maintenance and mate attraction. The songs of wild populations differ, forming local “dialects” that may shift over time, suggesting that cultural evolution is at work. Recent work has focused on the mechanisms responsible for the cultural evolution of bird songs within a population, including drift, learning biases (such as conformity and rare-form copying), and selection (including sexual selection). In many songs or song repertoires, variability is partitioned, with some songs or song segments being stable and consistent, while others vary within the population and across time, and still others undergo population-wide transitions over time. This review explores the different mechanisms that shape the cultural evolution of songs in wild populations, with specific reference to a long-term investigation of a single population of philopatric Savannah sparrows. Males learn a single four-segment song during their 1st year and sing the same song thereafter. Within this song, the buzz segment is a population marker, and may be stable for decades – variant forms occur but eventually disappear. In contrast, the middle segment is highly variable both within the population and over time; changes in relative prevalence of different forms may be due to cultural drift or a rare-form learning bias. Within the introductory segment, a high note cluster was replaced by a click train between 1982 and 2010, following an S-shaped trajectory characteristic of both selective sweeps in population genetics and the replacement of one form by another in human language. In the case of the Savannah sparrows, this replacement may have been due to sexual selection. In subsequent generations, the number of clicks within trains increased, a form of cultural directional selection. In contrast to the narrowing of a trait's range during directional selection in genetic systems, variation in the number of clicks in a train increased as the mean value shifted because improvisation during song learning allowed the range of the trait to expand. Thus, in the single short song of the Savannah sparrow, at least four different mechanisms appear to contribute to three different types of cultural evolutionary outcomes. In the future, it will be import to explore the conditions that favor the application of specific (and perhaps conditional) learning rules, and studies such as the ongoing song seeding experiment in the Kent Island Savannah sparrow population will help in understanding the mechanisms that promote or repress changes in a population's song.
Using shared songs is believed to be an integral part of neighbor communication and territory establishment strategies among many avian species with repertoires. Previous studies of two western subspecies of Song Sparrows (Melospiza melodia) reported a high level of song sharing among neighboring males, whereas studies of an eastern subspecies have reported a very low level. The purpose of our study was to investigate another population of the eastern subspecies to determine whether higher song-sharing levels existed within its range. Every song in the repertoire of 29 males was compared with the songs of all other males to assess the number of shared songs. For each male, we calculated the mean song-sharing level with neighbors and non-neighbors. Males shared, on average, 33% of their repertoire with neighbors, significantly more than they shared with non-neighbors (27% of their repertoire). Two first-year males learned whole song types from several individuals and preferentially learned the song types shared among those individuals. Our results suggest that the eastern and western subspecies may not differ genetically in the way they learn songs, because song-sharing levels and song learning in our population were more similar to those of the western subspecies than to those of other populations within its own subspecies. Song-sharing differences among eastern populations may be explained instead by factors acting at the level of individual populations.
Niveau Élevé de Chants Partagés chez une Population de l'Est de Melospiza melodia
Geographic variation in mating signals is of interest to evolutionary biologists because the consequences of spatial divergence may lead to behavioral discrimination, assortative mating, and speciation. Birdsong is a mating signal of songbirds, and geographic variation in the form of small-scale dialects or large-scale regiolects has been documented in many species. We studied macrogeographic variation in song of the MacGillivray's Warbler (Geothlypis tolmiei) to determine the pattern of song variation in this species. Hypotheses used to explain the evolution of song divergence were also examined. We found extensive individual variation in the cultural units and physical parameters of song that overwhelmed differences among populations. We did not find dialects in the breeding range but did find a pattern of clinal variation with song differences increasing with increasing geographic distances among populations. Hypotheses that explain patterns of song divergence in other species did not apply to MacGillivray's Warblers. Selection for novel songs that facilitates individual recognition may be important in this species that breeds in extremely dense vegetation. Extensive individual variation among male tutors within and among populations may also inhibit dialect formation and perpetuate song diversity in future generations.
The premise of this book is that our environmental dilemmas are products of biological and sociocultural evolution, and that through an understanding of evolution we can reframe debates of thought and action. The purpose is to explain the wide variety of environmental worldviews, their origins, commonalities, points of contention, and their implications for the modern environmental movement. In three parts covering the origins, evolution and future of environmentalism, it offers instructors and students a framework on which to map theory, case studies and classical literature. It is shown that environmentalism can be described in terms of six human values-utility, stability, equity, beauty, sanctity, and morality-and that these are deeply rooted in our biological and cultural origins. In building this case the book draws upon ecology, philosophy, psychology, history, biology, economics, spirituality, and aesthetics, but rather than consider these all independently it integrates them to craft a mosaic narrative of our species and its home. From our evolutionary origins a story emerges; it is the story of humankind, how we have come to threaten our own existence, and why we seem to have such difficulty in acting together to ensure our common future. Understanding our environmental problems in evolutionary terms gives us a way forward. It suggests an environmentalism in which material views of human life include spirituality, in which our anthropocentric behaviors incorporate ecological function, and in which environmental problems are addressed by the intentional relation of humans to the nonhuman world and to one another. Aimed at students taking courses in environmental studies, the book brings clarity to a complex and, at times, confusing array of ideas and concepts of environmentalism.
Geographic variation in song is widespread among birds, particularly in species that learn vocalizations. The relationship between geographic distance and song variation is likely related to the degree of isolation between populations. To assess this effect of geographic isolation on song divergence, we examined patterns of geographic song variation in four species of Australian fairy-wrens (Malurus), two with suspected histories of geographic isolation and two without. Song variation in all four species was consistent with patterns of isolation by distance, and allopatric subspecies in two species were more divergent in song than predicted by distance alone. Each species' pattern was unique, and some interspecific variation could not be explained by geographic distance. These results indicate that patterns of geographic variation can be influenced by more than geographic distance and historical isolation alone. We suggest that morphological constraints, environmental influences, and sexual selection may all contribute to the variation observed for each species.
The study of geographic variation of social mating systems can shed new light on our understanding of how ecological variables shape extant mating associations. We report data on the social mating system, parental care and life history traits of a temperate population of southern Sedge Wrens (Cistothorus platensis platensis) in South America. We compared our results with published records of two temperate populations of northern Sedge Wren (Cistothorus platensis stellaris) in North America. The southern temperate population had a lower social polygyny rate, greater male contribution to feeding nestlings and smaller clutch sizes than northern temperate populations. A similar pattern of low rates of social polygyny and smaller clutch sizes in the south versus moderate rates of social polygyny and bigger clutch sizes in the north has been reported for the House Wren (Troglodytes aedon). This suggests that different selective forces may be operating in northern and southern wren populations. Future work in additional study populations is essential to establishing the generality of our results.
We examined the phylogeography of the Western Hemispheric Sedge Wren (Cistothorus platensis) which occurs in grasslands from Canada to Tierra del Fuego. Genetic data indicate that Sedge Wren is paraphyletic with Mérida (Cistothorus meridae) and Apolinar's (Cistothorus apolinari) wrens and the currently recognized Sedge Wren is composed of a minimum of eight species. Speciation within this complex appears to have accelerated with the formation of the Isthmus of Panama which enabled the ancestor to occupy and differentiate in grassland habitats from sea level to above tree line in the Andes on the South American continent. As a result of the dramatic, negative anthropogenic impact on grasslands across the entire Western Hemisphere all species have suffered substantial declines and several are now threatened.
Songbirds have been traditionally classified into close-ended or open-ended learning species according to the length of the sensitive period during which birds are able to memorize new vocalizations. Closed-ended learners are generally not capable of changing their song after the first year of life, while open-ended learners show song plasticity as adults. A few Turdus species have been suggested to be open-ended learners, but no long-term study has been conducted to investigate their song plasticity over time. We analyzed the songs of clay-colored thrushes, T. grayi, over four successive breeding seasons to assess song plasticity in their syllable repertoires within and between breeding seasons. A total of 16,262 syllables were classified through visual inspection of spectrograms and multidimensional scaling analysis based on spectrogram correlations. On average, 563 ± 153 (SD) syllables per male per breeding season were analyzed. Male repertoire size was 9-20 syllable types. Males were capable of modifying their syllable repertoire between the initial and final periods of the breeding season. Song plasticity within breeding seasons may be associated with imitation between neighboring males, suggesting song learning in males that were ≥2 years old. This short-term plasticity is not enough, however, to explain the high proportion of change (mean = 65 % syllable types) in repertoire composition between breeding seasons in adult males. Song plasticity resulting from annual changes in repertoire composition could be explained by open-ended learning, but another mechanism, extended memory and re-expression, could also explain long-term plasticity. Experimental studies controlling the acoustic environment are needed to determine which mechanism is responsible for such a high level of song plasticity.
Detailed descriptions of song structure are critical to understanding the ontogeny, evolution, and function of bird song, particularly for species with large song repertoires. We provide a first detailed characterization of song organization and variability in a migratory population of House Wrens (Troglodytes aedon) breeding in western Canada, using a sample of 15,608 songs from 15 males. Males sang with high intensity in protracted bouts prior to pairing and often resumed high-intensity singing later in the breeding cycle to attract a second mate. The high-amplitude terminal portion of songs comprised rapid trills of frequency-modulated notes organized into discrete syllable types with a mean of 10 syllables and 4 syllable types per song. The population syllable repertoire was large (n = 27) and mostly shared but was used to produce much larger repertoires of song types, most of which were unique. Individual males sang up to 194 different song types, with no evidence of a ceiling. However, males sang most song types only rarely and, thus, had much smaller "effective" repertoires of similar to 25 song types. Within singing bouts, males also repeated song types many times before switching and modified the syllable contents of successive songs gradually. Hence, they combined tremendous global song diversity with limited real-time song variability. This mix may reflect central neural or peripheral motor constraints on short-term song diversity or, perhaps, selection simultaneously favoring both diversity and consistency in song performance.
A strong pattern has emerged between sedentary behaviour and song sharing between territorial neighbours for avian species that possess song repertoires. This paper investigates song-repertoire size, and rates of song sharing and type matching, in the Rufous Bristlebird (Dasyornis broadbenti), a southern Australian species for which there is strong evidence for sedentary and territorial behaviour. For 12 focal individuals (6 male, 6 female), estimated mean repertoire size was 31 song types for male birds, and 14 song types for females, recorded at the start of the breeding season. While the female song was similar in structure to the final phase of the male song, there was no sharing of song types between the sexes. A high degree of song sharing was exhibited in both sexes, with males sharing an average of 65% of song types, and females sharing 59% of song types, with immediate territorial neighbours. These rates of song sharing between neighbours were significantly greater than rates of song sharing between non-neighbouring individuals, although common song types between non-neighbours were encountered. Furthermore, bristlebirds used these common song types significantly more often than song types that were unique to their repertoires. While male neighbours preferentially matched song types, there was no evidence for repertoire matching. The degree of song sharing in neighbouring Rufous Bristlebirds is therefore consistent with the observed relationship between sedentary behaviour and high levels of song sharing.
Members of the genus Zosterops are known for their colonizing ability and extensive phenotypic differentiation on numerous islands. There have been morphological and biochemical analyses of some Zosterops populations, but little study has been devoted to patterns of vocal communication signals, known to be important pre-mating barriers in many bird species and in possible diversification of taxa. I report on the song system of one subspecies of Zosterops in a mainland population and an island population 15 km distant. I used both a traditional subjective classification of song elements and the multivariate procedure of linear discriminant analyses (LDA) of measured sound features. The syllables constituting songs exhibited a low level of stereotypy, disallowing a lexicon of syllable 'types' to be constructed for individuals or a population. New syllables were continuously produced as a bird uttered more and more songs, possibly indicating an extremely large repertoire or an open-ended generation of vocal innovations. LDA indicated songs of the island population were moderately differentiated from and less variable than those of the mainland. This type of song system creates a problem for research on vocal signals, whether directed at comparisons between birds in a local area or between populations. I made a preliminary effort to address this problem and discuss my results in the framework of Zosterops and its propensity for evolutionary diversification.
Many factors may influence the evolution of acoustic signals, including sexual selection, morphological constraints and environmental variation. These factors can play simultaneous and interacting roles in determining signal phenotypes. Here, we assess the evolution of song features in the Maluridae, a passerine family with significant variation among taxa in levels of sperm competition, morphological features and breeding habitats ranging from arid grasslands in Australia to tropical rainforests in New Guinea. We used phylogenetic comparative methods and a robust molecular phylogeny to compare song characteristics with a variety of other measures, including testes mass, body-size and latitude. Several aspects of the temporal and frequency structure of song were associated with relative testes mass, suggesting that sexual selection may influence some song characteristics in this family. The lowest frequencies of song were strongly predicted by body-size, indicating that morphological constraints have also likely influenced acoustic phenotypes. Song versatility, reflecting the diversity of note types in a song, was positively correlated with latitude, suggesting that complexity may increase in association with more temperate or variable environments. Variation in song structure across the family appears to reflect a complex interaction between natural and sexual selection.
Although the majority of oscine species acquire a song repertoire by imitating songs they have been exposed to, some species also improvise and invent songs. To test the hypothesis that American Robins (Turdus migratorius) both imitate and invent the elements of their whistle songs, I analyzed the song repertoires of wild robins at three locations in western Massachusetts and the song development of five tutor-trained nestling robins. Robins appear to invent or improvise most of the elements in their repertoires (75-82%), but as fledglings and juveniles they acquire the remaining elements by imitating the songs of neighboring birds.
This chapter examines the song learning in the oscine passerines (songbirds), with focus on the study species, the song sparrow. In most songbirds, song functions in the contexts of intrasexual competition and mate attraction. In most territorial temperate-zone passerines, only males sing and the major intrasexual context is the defense of the territory with song functioning as a long-distance signal to “post” the territory and to communicate with neighbors in negotiating the territorial boundaries. The chapter also discusses the social factors in song learning. The singing interactions between two neighbors who share some song types are shown diagrammatically. The song learning program of song sparrows has been characterized identifying eight “rules” that taken together might be considered an adaptive learning strategy. These are: (1) learn songs preferentially from conspecific singers, (2) complete song learning in the first year, (3) copy song types completely and precisely, (4) learn the songs of multiple birds, (5) learn from the neighbors, (6) preferentially learn or retain song types of those tutors who survive into the first breeding season, (7) preferentially learn tutor-shared songs, and (8) individualize (at least some of the songs in) the song repertoire.
In numerous species of birds, individuals or species that sing larger numbers of song types have larger song control nuclei in their brains. The direction of the cause and effect relationship between the complexity of song behavior and brain space is unknown, however. The hypothesis that birds that learn large song repertoires develop large song nuclei was therefore tested with a songbird, the marsh wren (Cistothorus palustris). Males were hand-reared and tutored in the laboratory with either small (n = 8 males heard 5 song types) or large (n = 8 males heard 45 song types) repertoires. When the birds were adults, the number of song types each male sang was first determined, and then the volume and certain cellular attributes of the song nuclei HVC and RA were measured. The two groups of wrens showed large behavioral differences in the size of their learned song repertoires, but did not differ in either the volumes of HVC and RA or in neuronal size, number, or density within these nuclei. These results suggest that the relationship between behavioral song complexity and brain space found in this and other species develops largely independently of early song learning experience and the later production of those songs.
We used a hierarchial approach to investigate the relationships among within- and between-year variation in precipitation and temperature in the northern Great Basin and components of reproductive success in two species of common shrubsteppe sparrows. During a 5-yr period we monitored clutch sizes, brood sizes, and fledging success in Sage (Amphispiza belli) and Brewer's (Spizella breweri) Sparrows in shrubsteppe habitat in central Oregon. During the 5 yr of our study, the Pacific Northwest experienced precipitation extremes, with the driest bioyear (October-April) in 65 yr of records (1976-1977) followed by one of the wettest. Within each breeding season daily temperature and precipitation fluctuated widely and in most cases unpredictably over a scale of a few days. Both species achieved significantly greater final reproductive success (as measured by number of fledglings produced) in wetter, presumably more biologically productive years. In Brewer's Sparrows this was achieved through higher clutch si
To what extent has the style of song development among songbirds coevolved with other life history strategies? AmongCistothoruswrens in North America, it seems that sedentary or site-faithful habits of marsh wrens,C. palustris, favour song imitation, but seminomadic habits of sedge wrens,C. platensis, favour song improvisation, whereby each male generates a large but unique song repertoire. In this study, we tested whether more sedentary populations of sedge wrens in the Neotropics would imitate songs. At our primary study site near Cartago, Costa Rica, breeding birds were colour-banded during 1995 and 1996, and follow-up surveys revealed that the birds remained at this site the year round. Extensive tape recording and analysis of songs showed that males had large song repertoires (200–300+ songs), and that many songs were shared among neighbouring males. In addition, males only 27 km distant, at La Pastora, used different songs. Furthermore, matched countersinging, in which two males answer each other with identical song types, was recorded near Brasilia, in Brazil. The sharing of songs among permanent neighbours, microgeographical variation in song, and matched countersinging can be achieved only through song imitation, thus revealing a striking difference in the style of song development among different populations of the sedge wren. In the Neotropics, having predictable neighbours throughout life appears to have favoured song imitation, so that individuals can interact using a common, learned code typical of the local population; among more mobile populations in North America, however, individuals improvise large repertoires of species-typical songs, thereby enabling singing males to communicate with any individual, no matter what the population of origin. Strategies of song development must correlate with life history features, and further surveys are needed to make sense of the great diversity of singing behaviours among songbirds.
For at least 30 years, there have been close parallels between studies of birdsong development and those of the development of human language. Both song and language require species-specific stimulation at a sensitive period in development and subsequent practice through subsong and plastic song in birds and babbling in infant humans leading to the development of characteristic vocalisations for each species. This book illustrates how social interactions during development can shape vocal learning and extend the sensitive period beyond infancy and how social companions can induce flexibility even into adulthood. Social companions in a wide range of species including birds and humans but also cetaceans and nonhuman primates play important roles in shaping vocal production as well as the comprehension and appropriate usage of vocal communication. This book will be required reading for students and researchers interested in animal and human communication and its development.
For at least 30 years, there have been close parallels between studies of birdsong development and those of the development of human language. Both song and language require species-specific stimulation at a sensitive period in development and subsequent practice through subsong and plastic song in birds and babbling in infant humans leading to the development of characteristic vocalisations for each species. This book illustrates how social interactions during development can shape vocal learning and extend the sensitive period beyond infancy and how social companions can induce flexibility even into adulthood. Social companions in a wide range of species including birds and humans but also cetaceans and nonhuman primates play important roles in shaping vocal production as well as the comprehension and appropriate usage of vocal communication. This book will be required reading for students and researchers interested in animal and human communication and its development.
For at least 30 years, there have been close parallels between studies of birdsong development and those of the development of human language. Both song and language require species-specific stimulation at a sensitive period in development and subsequent practice through subsong and plastic song in birds and babbling in infant humans leading to the development of characteristic vocalisations for each species. This book illustrates how social interactions during development can shape vocal learning and extend the sensitive period beyond infancy and how social companions can induce flexibility even into adulthood. Social companions in a wide range of species including birds and humans but also cetaceans and nonhuman primates play important roles in shaping vocal production as well as the comprehension and appropriate usage of vocal communication. This book will be required reading for students and researchers interested in animal and human communication and its development.
Among songbirds, adult song forms usually are determined culturally during an individual's early experience. In the Marsh Wren (Cistothorus palustris), we have demonstrated that the quantity of this learned behavior (i.e. song repertoire size), its style of delivery, and the size of controlling nuclei in the forebrain have a genetic basis. Nestling males taken from New York and California and reared under standardized conditions in the laboratory still develop population-typical behavior and neuroanatomy. We do not know the developmental mechanisms responsible for these differences, but we believe that year-round residency, high densities, and polygynous mating systems are likely factors contributing to an escalation of vocal abilities in the western populations.
Author Institution: Academic Faculty of Population and Environmental Biology, College of Biological Sciences, The Ohio State University, and the Ohio Historical Society, Columbus, Ohio
Birds have been studied for centuries because they are numerous, conspicuous, and aesthetically pleasing to humans Despite their overall regard for birds, historically, many ornithologists have considered birds as instinct-driven organisms of little intellectual capacity. For example, the ornithological textbook of choice from the 1960s states the following view of avian intelligence:
Flight has proven to be an enormously successful evolutionary venture, but one that has cost birds dearly in mental development. In effect, flight has become a substitute for cleverness; birds solve many potential problems merely by flying away from them…. As a consequence, much [avian] behavior is, by mam-malian standards, fragmentary, stereotyped, and at times amazingly stupid. (Welty, 1962, p.159).
Polygamy in avian mating systems has generally been interpreted as a by-product of an unbalanced sex ratio, an assumption which is not necessarily true but which has apparently led to a stagnation of thought concerning evolution of polygamy in birds. Monogamy in populations with highly skewed sex ratios is known, and polygamy occurs in populations with even sex ratios. The Long-billed Marsh Wren falls into the latter group. Field studies in two separate populations of the marsh wren in Washington State revealed that bigamous associations were formed even when territorial bachelors were present in the vicinity, the bachelors being judged to occupy inferior territories. A female selecting a mate under these conditions might rear more young by pairing with a mated male on a superior territory than with a bachelor on an inferior one, notwithstanding the fact that she would obtain less help from her mate. A necessary correlate to this idea is a high density of mature males, such that some are forced to occupy the marginal sites. Monogamous populations of normally polygamous species (e.g., the marsh wrens of Sapelo Island, Georgia; European Wrens on various islands in the northern British Isles) may not occur in sufficient numbers during the breeding season to force some males into marginal habitats. An attempt is made to suggest some characteristics of males and their territories that are related to pair formation. There is evidence that the size of a male's territory and the total amount of emergent vegetation in it are correlated with his success in acquiring mates. Males' song rates tend to show an inverse correlation to pairing success, and males that failed to construct courting nests never paired. Whether features of territories or of males are important in pair formation, those factors leading to a high probability of pairing success must somehow be correlated with a high probability of breeding success.
Do songs of songbirds, which learn to sing, provide reliable clues to genetic identity in zones of secondary contact? How do some songbird species maintain such highly stereotyped songs throughout extensive geographic ranges? These two questions were addressed with a study of song development by Carolina and Black-capped chickadees (Paruscarolinensis and P. atricapillus). In one hand-reared, mixed group in the laboratory, male Carolina Chickadees produced better imitations of a tape-tutored Black-capped Chickadee fee-bee song than did two male Black-capped Chickadees. In another mixed group, a male Black-capped Chickadee produced a better imitation of tape-tutored Carolina Chickadee song elements than did the Carolina Chickadee males themselves. Black-capped Chickadees in an additional experiment were tutored with normal fee-bee songs and with fee-fee, bee-bee, and bee-fee songs; these males also produced highly abnormal songs, although songs of males within groups converged on one another,reinforcing ideas that social interactions are crucial for the song learning process. These data thus reveal that song in secondary contact zones of these chickadees is probably not a good indication of genotype. The feat of Black-capped Chickadee song stereotypy in nature, together with other features of their singing behavior(e.g. social and hormonal determinants of singing, subsong by both sexes but loud songs only from males), remain both puzzling and fascinating.
Young zebra finch males were tested for their ability to acquire species-specific song before reaching independence. Song copies developed by males kept with their fathers up to 35 days posthatching were as complete as those of males that remained in contact with their fathers until day 100, when song crystallization has finished. Young males can learn the entire song during a brief period early in life. This early acquisition phase and its influence on further song learning at a later age make it likely that males in the field will develop a song similar to that of their fathers.
AasTa,&m.-Black-capped Chickadees (Parus atricapilhs) sing a two-note tonal song that has stereotyped frequency parameters (glissando and frequency interval). We hand-reared and tutored pairs of nestlings in acoustic isolation to determine the extent that learning is involved in the production of these parameters. Each pair of birds was tutored with a high frequency fee-bee song, a low frequency fee-bee song, or a low frequency fee only. Song gradually developed from a warbling subsong to sustained, whistled notes. Individuals did not match the absolute frequency of their tutor songs and sang over as wide a range of frequencies as adult males do in the wild. Five of the 10 males incorporated some normal frequency parameters of the tutor songs into their own songs. None of the birds tutored with only fee sang with a normal frequency interval, even though they did sing songs with more than one note. Males tutored with each of the other two songs did learn to sing with the correct interval. Our results suggest that the structure of Black-capped Chickadee song is open to environmental influences and that chickadees may learn the relative frequency
Many songbirds overproduce songs during development and shrink the repertoire at the time of adult crystallization. The amount of overproduction varies between species. The hypothesis was tested that overproduction of learned songs during ontogeny is correlated with a migratory annual cycle. It is argued that in migrants, overproduction permits song matching between territory neighbours when song memorization is restricted to an early sensitive phase and young males subsequently disperse relatively long distances to their first breeding territory. Song development was compared in the sedentary Nuttall's white-crowned sparrow,Zonotrichia leucophrys nuttalli, and two migratory taxa, the Puget Sound white-crowned sparrow,Z.l.pugetensis, and the mountain white-crowned sparrow,Z.l.oriantha. Although the Puget Sound and Nuttall's white-crowned sparrows are sister taxa, male Puget Sound sparrows more closely resembled the more distantly related, but migratory, mountain white-crowned sparrow on every measure of song development studied. It is concluded that a migratory annual cycle is a better explanation of diversity in vocal development in this species than recency of common ancestry.
Repertoire sizes and song development among birds must be understood as facets of life history strategies. In some groups
repertoires appear related to population densities, with more frequent interactions in dense populations leading to an escalation
of signal diversity. The extent and timing of vocal learning also differs among taxonomic groups and depends to some extent
on habitat stability, site fidelity, and dispersal strategies of young.
For at least 30 years, there have been close parallels between studies of birdsong development and those of the development of human language. Both song and language require species-specific stimulation at a sensitive period in development and subsequent practice through subsong and plastic song in birds and babbling in infant humans leading to the development of characteristic vocalisations for each species. This book illustrates how social interactions during development can shape vocal learning and extend the sensitive period beyond infancy and how social companions can induce flexibility even into adulthood. Social companions in a wide range of species including birds and humans but also cetaceans and nonhuman primates play important roles in shaping vocal production as well as the comprehension and appropriate usage of vocal communication. This book will be required reading for students and researchers interested in animal and human communication and its development.
This chapter discusses on the recent findings in song learning in zebra finches and brings them together with earlier studies of song learning in this species, as well as recent physiological work on this species that is relevant to song development. Zebra finch song also affords excellent prospects for further advances in our understanding of principles of behavioral development; the review concludes by considering some of these remaining questions. The chapter summarizes briefly on what is known of the way of life of the zebra finch in the wild, where it occurs in Australia and the Lesser Sunda islands. It is an intensely sociable species, occurring in large flocks and breeding colonially in response to the rainfall, which is essential if there is to be sufficient food for feeding chicks. Zebra finch song seems largely to act as a signal between the sexes, although it is simple in structure and does not therefore fit easily into the scheme of song function. Rather than being concerned primarily with mate attraction or rival repulsion, its major role may be in stimulating ovarian development, including ovulation, a function song is known to possess in other species. This chapter describes what is known about the song-learning system in zebra finches and suggest ways in which the timing, accuracy, and selectivity of learning is affected by the environment that the young bird experiences during its development.
Sedge Wrens (Cistothorus platensis) are very rare breeders in the central plains states but show a pattern of mid-summer arrival dates. I examined their status in central Nebraska in August 1994 by conducting six Breeding Bird Survey routes and by searching suitable habitat. I recorded Sedge Wrens on three of the six survey routes. Most wrens occurred on sub- irrigated native meadows, but a variety of grassland types were used. Most clutches were initiated by the second week of August. Observers should be aware of the potential for late-summer breeding in other portions of their range.
This paper examined the relative importance of visual and vocal cues for song tutor choice. In the first study zebra finches, Taeniopygia guttata, and Bengalese finches, Lonchura striata, were housed with two song tutors at independence, a zebra finch singing Bengalese finch song and a Bengalese finch singing zebra finch song. All the males tended to learn from the conspecific song tutor, irrespective of whether they had been raised by a pair of conspecifics, the female alone or cross-fostered to a pair of the other species. In the second study zebra finches were housed at independence with two conspecific song tutors, one with a normal song and one which sang Bengalese finch song elements. There was no tendency to learn zebra finch elements which suggests that species-specific elements are not important for song tutor choice in zebra finches. Other vocal differences between the tutors such as length of the song phrase and species-specific call notes might bias learning in favour of the conspecific. Visual differences between the two species, both in appearance and behaviour, seem to be important. Parental cues before independence appear to be relatively uninfluential. However, siblings may be important, both the species and number per clutch: this is a factor which has been overlooked in previous studies of song learning.
Experience during brief periods of development can exert a profound influence on later life1. Among songbirds, experimental evidence for enhanced vocal learning during a relatively brief period early in life is well documented2,3. The timing of vocal learning with respect to dispersal is fundamental to our understanding of many population processes, yet the significance of the sensitive period remains unclear. We report here that in our study of the marsh wren (Cistothorus palustris), a North American songbird, we found that the sensitive period for song learning is not rigidly programmed with respect to dispersal and/or migration; two environmental factors, the photoperiod and the amount of adult song heard during the hatching year, influence the nature of the sensitive period during the hatching year, the ability to learn further the next spring, and the relative dates at which young males develop their adult songs.
No single theory so far proposed gives a wholly satisfactory account of the origin and maintenance of bird-song dialects. This failure is the consequence of a weak comparative literature that precludes careful comparisons among species or studies, and of the complexity of the issues involved. Complexity arises because dialects seem to bear upon a wide range of features in the life history of bird species. We give an account of the principal issues in bird-song dialects: evolution of vocal learning, experimental findings on song ontogeny, dialect descriptions, female and male reactions to differences in dialect, and population genetics and dispersal.
We present a synthetic theory of the origin and maintenance of song dialects, one that accommodates most of the different systems reported in the literature. The few data available suggest that large, regional dialect populations are genetically differentiated; this pattern is correlated with reduced dispersal between dialects, assortative mating by females, and male-male exclusion. At the same time, “subdialects” may be formed within regional dialects. Subdialect clusters are usually small and may represent vocal mimicry among a few adjacent territorial males. The relative importance of genetic and social adaptation may contribute to the emergence of subdialects; their distinctiveness may be correlated with the degree of polygyny, for example. Thus, subdialect formation is linked to one theory of the evolution of repertoire size, but data are too fragmentary to examine this idea critically.
Imitative song development, its requisite auditory feedback, and the underlying neural control of learned song are becoming increasingly well known in songbirds, but the evolution of these characteristics from songbird ancestors is poorly understood. Suboscine flycatchers, which belong to the evolutionary sister group of the oscine songbirds (in the same order, Passeriformes), are thought not to imitate songs from other individuals. This study therefore examines the role of auditory feedback in song development and provides preliminary comments on neural control. Four eastern phoebes, Sayornis phoebe, were collected at 10–12 days of age and hand-reared in the laboratory; at approximately 35 days of age, before they began to sing, the birds were bilaterally deafened by removal of the cochlea. Songs of these phoebes, two males and two females, were judged to be normal when compared with songs of males recorded in nature and to songs of laboratory-reared, intact males and females. Like several non-passerines (representatives of Galliformes and Columbiformes), the eastern phoebe requires no auditory feedback for normal vocal development. Brain sections of phoebes contain no obvious cell clusters like the forebrain song nuclei of songbirds. If some of these nuclei mediate auditory feedback control of song development, the apparent absence of these nuclei in the phoebe is consistent with its ability to develop normal song without auditory feedback.
When vocal variability, here measured by song repertoire size, increases in songbirds, it may become increasingly difficult to encode genetically all the information which is required to ensure the learning of only conspecific songs. Marsh wrens (Cistothorus palustris) have sizeable song repertoires, and while no vocal mimicry is evident in the field, males will readily learn heterospecific songs in the laboratory. These data, together with data from the literature, support the proposed relationship between increased repertoire sizes and reduced specificity of the innate auditory template which guides vocal learning.
Male marsh wrens (Cistothorus palustris) do not ordinarily learn songs from tutor tapes during their first spring, but in two experiments all five males given an opportunity to learn from a live the timing and significance of events in nature. There was marked individual variation in the responses of subjects to seemingly identical laboratory conditions; such differences among individuals are unexplainable but intriguing and warrant further study as more than mere ‘experimental noise’.
The Iowa Breeding Bird Atlas
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- C A Thompson
- J J Dinsmore
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- R Cecil
- L M He-Mesath
- S J And
- Dinsmore
JACKSON, L. S., C. A. THOMPSON, J. J. DINSMORE, B. L. EHRESMAN, J. FLECKENSTEIN, R. CECIL, L. M. HE-MESATH, AND S. J. DINSMORE. 1996. The Iowa Breeding Bird Atlas. University of Iowa Press, Iowa City.
Birds in Minnesota Aspects of learning in the on-togeny of bird song: Where, from whom, when, how many, which, and how accurately? Pages 215-230 in Development of behavior Vocal dueling among male Marsh Wrens: Evidence for ritualized expres-sions of dominance/ subordinance
- R B Janssen
- Minneapolis
- D E Kroodsma
JANSSEN, R. B. 1987. Birds in Minnesota. University of Minnesota Press, Minneapolis. KROODSMA, D. E. 1978. Aspects of learning in the on-togeny of bird song: Where, from whom, when, how many, which, and how accurately? Pages 215-230 in Development of behavior (G. Burg-hardt and M. Bekoff, Eds.). Garland Press, New York. KROODSMA, D. E. 1979. Vocal dueling among male Marsh Wrens: Evidence for ritualized expres-sions of dominance/ subordinance. Auk 96:506-515.
Ontogeny of bird song. Pages518-532 in Early development in man and ani-mals. The Bielefeld project
- D E Kroodsma
KROODSMA, D. E. 1981. Ontogeny of bird song. Pages 518-532 in Early development in man and ani-mals. The Bielefeld project (K. Immelmann, G. Barlow, L. Petrinovich, and M. Main, Eds.).
Ecology of passerine song de-velopment. Pages 3-19 in Ecology and evolution of acoustic communication in birds Song development by Black-capped Chickadees (Parus atricapillus) and Carolina Chickadees (P carolinensis)
- D E E Kroodsma
- D J Albano
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- And J A Wells
KROODSMA, D. E. 1996. Ecology of passerine song de-velopment. Pages 3-19 in Ecology and evolution of acoustic communication in birds (D. E. Kroodsma and E. H. Miller, Eds.). Cornell Uni-versity Press, Ithaca, New York. KROODSMA, D. E., D. J. ALBANO, P. W. HOULIHAN, AND J. A. WELLS. 1995. Song development by Black-capped Chickadees (Parus atricapillus) and Carolina Chickadees (P carolinensis). Auk 112: 29-43.
Sedentary life style of Neotropical Sedge Wrens promotes song imitation Complex singing behaviors among Cistothorus wrens
- M L Goodwin
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GOODWIN, M. L. DA SILVA, AND J. M. E. VIEL-LIARD. 1999. Sedentary life style of Neotropical Sedge Wrens promotes song imitation. Animal Behaviour 57: in press. KROODSMA, D. E., AND J. VERNER. 1978. Complex singing behaviors among Cistothorus wrens. Auk 95:703-716.
The atlas of breeding birds of Vermont Nesting ecology of Sedge Wrens in Hall County
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Academy of Natural Sciences, Philadelphia, and American Ornithologists' Union, Washington, D.C. LAUGHLIN, S. B., AND D. P. KIBBE. 1985. The atlas of breeding birds of Vermont. University Press of New England, Hanover, New Hampshire. LINGLE, G. R., AND P. BEDELL. 1989. Nesting ecology of Sedge Wrens in Hall County, Nebraska. Ne-braska Bird Review 57:47-49.
Subsong and plasticsong: Their role in the vocal learning process.Pages 25-50 in Acoustic communication in birds
- P Marler
- S Peters
MARLER, P., AND S. PETERS. 1982. Subsong and plastic song: Their role in the vocal learning process. Pages 25-50 in Acoustic communication in birds (D. E. Kroodsma and E. H. Miller, Eds.). Aca-demic Press, New York. MEANLEY, B. 1952. Notes on the ecology of the Short-This content downloaded from 129.89.24.43 on Tue, 19 Mar 2013 13:17:33 PM All use subject to JSTOR Terms and Conditions rows: A hierarchical analysis. Ecology 72:1325-1335.
Sedge Wrens nesting into September
- M D Schwilling
SCHWILLING, M. D. 1982. Sedge Wrens nesting into September. Kansas Ornithological Society Bul-letin 33:22-23.
Breeding birds of North Da-kota. Tri-College Center for Environmental Studies
- R E Stewart
STEWART, R. E. 1975. Breeding birds of North Da-kota. Tri-College Center for Environmental Studies, Fargo, North Dakota.
Studies of the Short-billed Marsh Wren (Cistothorus stellaris) in Michigan
- L H Walkinshaw
WALKINSHAW, L. H. 1935. Studies of the Short-billed Marsh Wren (Cistothorus stellaris) in Michigan. Auk 52:362-369.
Aspects of learning in the on-togeny of bird song: Where, from whom, when,how many, which, and how accurately? Pages215-230 in Development of behavior
- D E Kroodsma
When and how are pop-ulations limited? The roles of insect outbreaks,fire, and other natural perturbations. Pages 55-84 in Ecology and management of Neotropicalmigratory birds: A synthesis and review of crit-ical issues
- J T Rotenberry
- R J Cooper
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The ecological and socialsignificance of duetting. Pages 1-23 in Acousticcommunication in birds
- S M Farabaugh
- Walkinshaw
- American Ornithologists' Union