Distinct Song Types Research Articles

The song structure and seasonal patterns of vocal behavior of male and female bellbirds (Anthornis melanura)

The bellbird (Anthornis melanura) is a honeyeater endemic to New Zealand, which uses song to defend breeding territories and/or food resources year round. Both sexes sing and the song structure and singing behavior have not yet been quantified. The number of song types, spectral structure, repertoire size, and singing behavior of male and female bellbirds was investigated for a large island population. Song types differed between the sexes with males singing a number of structurally distinct song types and females producing song types that overlapped in structure. Singing behavior also differed between the sexes; males often sung long series of songs while females sung each song at relatively long and variable intervals. Singing by both sexes occurred year round but the frequency of male and female singing bouts showed contrasting seasonal patterns. The frequency of female singing bouts increased as the breeding season progressed, whereas male singing bouts decreased. In contrast to almost all studied passerines, female bellbirds exhibited significant singing behavior and sung songs of complex structure and variety that parallel male song. These results provide a quantitative foundation for further research of song in bellbirds and in particular the function of female vocal behavior.

Song repertoire size predicts initial mating success in male song sparrows, Melospiza melodia

Male song sparrows sing repertoires of 4–13 distinct song types and have proved a valuable model for testing hypotheses concerning the function and evolution of song complexity. Captive female song sparrows solicit more copulations in response to playback of larger repertoires, yet it remains unclear whether male repertoire size influences female mate choice in natural situations. We used long-term data from free-living song sparrows inhabiting Mandarte Island, British Columbia, Canada, to investigate whether male song repertoire size predicted three components of reproductive performance during the first year: territory acquisition, mating success and laying date. Across males whose song was recorded, males with larger repertoires were not more likely to acquire a territory, to acquire a larger territory or to settle sooner. However, after we controlled for territory size and between-year variation in the population sex ratio, first-year males with larger repertoires were more likely to mate. This was because they were more likely to pair with newly settled females, not because they were more likely to acquire territories where older females were already resident. After we controlled for territory size and between-year variation in breeding date, newly settled females laid earlier when mated with males with larger repertoires. Together with the results of previous mate choice experiments, these patterns are consistent with the hypothesis that male song repertoire size is a sexually selected trait that influences female mate choice in song sparrows.

Song repertoire evolution and acoustic divergence in a population of black-capped chickadees, Poecile atricapillus

Socially learned vocalizations, such as the songs of many songbirds, commonly show repertoires and geographical variation or dialects, but we have only a limited understanding of the cultural evolutionary processes that produce these patterns. In this paper we describe the singing behaviour of populations of black-capped chickadees in Fort Collins, Colorado that represents the apparent evolution of a repertoire of song types. In contrast to most black-capped chickadee singing behaviour, which consists of a single song type that is remarkably invariant across North America, chickadees throughout Fort Collins sing three acoustically distinct song types. Individual males have an average repertoire of 2.8 song types and use all of them in dawn bouts and countersinging with neighbouring males. Two of the three song types contain novel introductory notes. These notes and the ratio between the pitches of the two whistled notes used in the song consistently define each song type. Individual birds slightly vary the pitches used during a bout of singing for a particular song type but always maintain a constant pitch ratio for that type. The song type repertoire appears to be restricted to the Fort Collins area and has persisted for several years. We outline some of the cultural evolutionary processes that may have produced this repertoire and conclude by discussing research opportunities that may yield insight into how and why socially learned traditions originate and evolve.

Geographic Variation in the Organization of Song Sparrow Repertoires

Abstract We asked whether geographic variation exists in the complexity of song repertoires in Song Sparrows (Melospiza melodia) by quantitatively comparing four measures of repertoire organization across four geographically distant populations: (1) repertoire size (the number of distinct song types), (2) the number of “minimal units of production” per repertoire, (3) mean similarity among variants of the same song type (“within-type” similarity), and (4) mean similarity among song types in a repertoire (“between-type” similarity). We found significant geographic differences among populations in three of these four measures, with mean similarity among song types being the exception. In general, relatively sedentary populations in North Carolina and Washington were more similar to each other than to migratory populations in Pennsylvania and Maine. Contrary to our expectation based on prior interspecific analyses of variation in repertoire complexity, the relatively sedentary populations in our sample had more complex repertoires than did the more migratory populations. The origin and functional significance of population differences in repertoire complexity in this species remain uncertain.

GEOGRAPHIC VARIATION IN THE ORGANIZATION OF SONG SPARROW REPERTOIRES

Abstract We asked whether geographic variation exists in the complexity of song repertoires in Song Sparrows (Melospiza melodia) by quantitatively comparing four measures of repertoire organization across four geographically distant populations: (1) repertoire size (the number of distinct song types), (2) the number of “minimal units of production” per repertoire, (3) mean similarity among variants of the same song type (“within-type” similarity), and (4) mean similarity among song types in a repertoire (“between-type” similarity). We found significant geographic differences among populations in three of these four measures, with mean similarity among song types being the exception. In general, relatively sedentary populations in North Carolina and Washington were more similar to each other than to migratory populations in Pennsylvania and Maine. Contrary to our expectation based on prior interspecific analyses of variation in repertoire complexity, the relatively sedentary populations in our sample had m...

Geographic variation in the occurrence of song types in Nuthatch Sitta europaea populations

The frequency of occurrence of song types of Nuthatches Sitta europaea was examined in nine study areas in northern Belgium. Birds from different areas did not differ consistently in the use of five distinct song types, and similarity in the occurrence of song types was not related to geographic distance, except that one song type, “Ud”, was almost wholly absent from four areas in the northeast of the investigated area. In the remaining areas, the frequency of occurrence of this song type varied from 10% to 20%. This presence/absence pattern appears to be stable between years. I suggest that the birds from the four areas lacking “Ud” were descended from a formerly small and highly isolated population near Antwerp, where the song may have been lost through a founder effect. Birds in areas with and without “Ud” did not differ in their response level to playback of this song, except that those in areas without “Ud” were incapable of song matching.

Repertoire matching between neighbouring song sparrows

A male song sparrow, Melospiza melodia, has a song repertoire of about eight or nine distinct song types, and he typically shares several of these song types with each of his several neighbours. In the prevailing theoretical view, the song types in a bird's repertoire are interchangeable and multiple song types exist primarily to provide diversity. The present study was designed to test a contrary hypothesis concerning one particular context, counter-singing between neighbours. Specifically, the hypothesis was tested that song sparrows reply to the songs of particular neighbours with particular songs from their repertoire: they select a song type they share with that neighbour (‘repertoire matching’). In a field experiment, neighbour song was played to the subject from just inside the neighbour's territory. Subjects responded with a song shared with that neighbour in 87.5% of trials (chance expectation for this sample is 42%). In control trials, where stranger song was presented from the same location, subjects responded with songs shared with the neighbour at that location in only 17% of the trials. It is suggested that ‘repertoire matching’ may be one advantage of a song learning strategy that produces song sharing between neighbours.

Temporal patterning of within-song type and between-song type variation in song repertoires

In many songbird species, males sing a reper- toire of distinct song types. Song sparrows typically are described as having repertoires of about a dozen song types, but these song types are themselves quite variable and some songs are produced that appear intermediate between two types. In this study we quantify the similar- ity between successive songs produced by song sparrows in order to determine if differences between song types are emphasized or deemphasized in bouts of continuous singing. In spite of the high degree of variation within song types and similarity between song types observed in this species, we show that transitions from one song type to the next are distinct as compared to transitions within sequences of the same type (Figs. 4 and 5). Variation does not "accumulate" across sequences of the same song type, and the average variation observed within a continuous sequence of the same song type is significantly less than is predicted from the total variation recorded for that type across many different bouts (Fig. 6). These results sup- port the view that song sparrows include two levels of variation in their singing: differences between song types as is commonly observed in species with song repertoires, and an independent level of variation observed for songs of the same type.

Song Perception in the Song Sparrow: Importance of Different Parts of the Song in Song Type Classification

AbstractSong sparrow (Melospiza melodia) males have repertoires of 6 to 12 song types, each song consisting of four or five contrasting phrases. Song types vary both within individuals (a singer varies successive renditions of a type within a singing bout) and between individuals (neighbors sing slightly different versions of a type), and in both cases this variation is concentrated in the later parts of the song. We speculated that type variation in the later parts of the song might be correlated with a perceptual tendency to classify song types primarily on the basis of the earlier parts of the song. We tested this hypothesis using a laboratory conditioning technique, supplemented by a field playback experiment. In the lab, song sparrows and white crowned sparrows were trained to discriminate between two distinct song types. In test sessions, they were presented with hybrid songs synthesized from varying proportions of the two training song types. For most birds and most song pairs, song classification was influenced by all parts of the song, with the beginning elements being most important. The field playback experiment used song type matching as the response measure. Each subject was presented a hybrid stimulus song consisting of the first half of one of his song types and the second half of another of his song types. Subjects replied with both ‘front matches’ and ‘back matches’ (60% were front matches).

Song Sharing and Local Dialects in a Population of the European Wren Troglodytes Troglodytes

AbstractSongs were recorded from a local population of 13 male wrens at Wraysbury Lakes, Berkshire, U.K. during 1991. Sonagraphic analysis revealed that there were 15 distinct song types in the population, and that each male had between three and six song types in his repertoire. Song sharing between neighbouring males was particularly high. Six of the males in the population were on the east bank of the lake, separated from the other seven on the west bank by 200 metres of open water. Although three song types were distributed over the whole area, six were unique to the east bank and six to the west. Any male could be classified as an east or west bank male, by the possession of several distinct song types unique to each 'dialect' area. So far, clear examples of dialects have been largely restricted to species with only one or two song types in their repertoires. Song sharing and the development of local dialects in the wren are discussed in relation to current views on mechanisms of social learning in songbirds.

Song Categories and Their Functions in the Field Sparrow (Spizella pusilla)

-TWO song categories, distinguished by their acoustic structure, contextual usage, and potency in provoking responses from territorial males, are found in repertoires of individual male Field Sparrows (Spizella pusilla). Simple songs are sung spontaneously throughout the day and in long-distance countersinging by territorial males. Complex songs are sung most frequently during the dawn chorus and during territorial boundary chases. Most males sing one simple and one complex song type. Males responded more strongly to playback of complex songs than to simple songs. Our experiment supports the hypothesis that male songbirds respond differently to songs that are sung in different contexts. Received 13 November 1989, accepted 11 July 1990. IN MANY species of passerine birds, males sing two or more acoustically distinct song types (reviews in Krebs and Kroodsma 1980, Kroodsma 1982). Many hypotheses have been proposed to explain the proliferation of song types within repertoires. One class of hypotheses assumes that all songs within a species' repertoire contain the same information. Repertoires of redundant song types may be favored by both intraand intersexual selection. Large repertoires could function as effective keep-out signals by decreasing habituation in listening males (Krebs 1976), or by appearing to represent the presence of several singers (Krebs 1977). Large repertoires might also be favored by females during mate choice (Howard 1974, Catchpole 1980). Accordingly, songs should be used interchangeably and should provoke indistinguishable responses from listeners. A second class of hypotheses assumes that different song types within a repertoire provide different information to listeners. Different song types are sung in different behavioral contexts, and thus appear to provide different information to listeners (Morse 1970, Ficken and Ficken 1970, Lein 1978, Smith et al. 1978, Payne 1979, Jarvi et al. 1980, Sossinka and Bohner 1980, Catchpole 1983, Gaddis 1983, Nelson 1985, Derrickson 1987, Trainer 1987). In some warblers, males share different temporal patterns of song delivery in different contexts (MacNally and Lemon 1985, Staicer 1989). In species where song usage varies with behavioral context, different I Present address: Department of Zoology, University of California, Davis, California 95616 USA. songs may provide information on the singer's intentions or motivation (Lein 1978) and fighting ability (Lemon et al. 1987). In some species it has been suggested that some songs are directed primarily at females, while others within the repertoire are used primarily in male-male interactions (Morse 1966, 1967; Kroodsma et al. 1989). According to these hypotheses, which are not mutually exclusive, different song types should provoke different responses from recipients. To distinguish between these two forms of repertoire organization, we refer to song types that have different behavioral or contextual correlates as different song categories. In a similar way, Schroeder and Wiley (1983) grouped song types of the Tufted Titmouse (Parus bicolor) into classes based on usage and structure, and others have referred to song groups (Nolan 1978) or modes (MacNally and Lemon 1985). We suggest that three criteria must be met for song types to be separated into distinct categories: the song types must differ acoustically, they must be used in different behavioral contexts or reliably predict different subsequent behaviors, and they must elicit different responses from listeners in playback tests. If these criteria are met, a strong case is made that the songs serve different functions and convey different messages. Although we are concerned here with song-type variation, other aspects of song, such as the pattern of song delivery, could vary across contexts and so cause songs to be grouped into different categories. We documented the occurrence of two song types in male Field Sparrows (Spizella pusilla), a species in which males were previously re42 The Auk 108: 42-52. January 1991 This content downloaded from 207.46.13.21 on Tue, 27 Sep 2016 04:21:14 UTC All use subject to http://about.jstor.org/terms January 1991] Song Categories and Functions 43 ported to sing a single song type (Goldman 1973, Heckenlively 1976, Morrison-Parker 1977, Searcy 1983). Most studies of song repertoires have identified song types by subjective visual examination of sonograms. In Part 1 we present a quantitative acoustic analysis of song variation that supports the classification of songs into discrete acoustic categories, and we also estimate the size of individuals' song repertoires. In Part 2 we present observations of the contexts of singing. In Part 3 we describe an experiment to support the hypothesis that the two song types convey different messages, thus constituting distinct song categories. STUDY LOCATION AND OBSERVATIONAL

Response of territorial male song sparrows to song types and variations

The song repertoires of male song sparrows (Melospiza melodia) are comprised of distinct song types and many overlapping variations within each type. This study examines the sensitivity of territorial male song sparrows to both multiple song types and variation within types. A playback experiment was conducted using stimulus tapes that had either single songs (but not variations), song variations (but not types) or a single song. Response during playback was similar for all three stimulus groups, but diminished sooner after playback for the single-song tape. Thus our results indicate that male song sparrows are sensitive to song variability both within and among song types.

Yearly and Situational Changes in the Estimate of Repertoire Size in Northern Mockingbirds (Mimus polyglottos)

Abstract The singing behavior of 4 male Northern Mockingbirds (Mimus polyglottos) was studied during 1980 and 1981. Over 10,000 song bouts (repetition of a particular song type) were analyzed spectrographically. Between 102 and 412 distinct song types were identified for each male in a given year. Many of these song types (25.8-57.4%) occurred only once in this sample of singing behavior. Repertoire size was estimated by fitting an exponential curve to a cumulative plot of distinct song types as a function of consecutive bouts sampled. The resulting asymptote was the estimate of repertoire size. Sequences of at least 50 consecutive bouts were used in estimating repertoire size. The technique of using consecutive bouts was required because of the high proportion of rare song types. Several estimates were made for each male and resulted in mean repertoire size estimates of 100-200 song types for the four males. Long sequences (125-150 bouts) of consecutive bouts are preferred to estimate repertoire size accurately. In addition, the social situation in which the singing behavior occurred can alter significantly the estimate of repertoire size. For example, estimates produced from singing during patrolling or countersinging were smaller than estimates generated from singing while associating with a female. The repertoire size estimate increased between 1980 and 1981 for 3 of 4 males. The one male not showing an increase spent much time patrolling and interacting with neighboring males before dying early in 1981. These results are consistent with the impression that repertoire size increases with age.

Song switching and agonistic stimulation in the song sparrow ( Melospiza melodia): five tests

Male song sparrows in southeastern Ontario have repertoires of five to 11 distinct song types. The singer repeats each song type a variable number of times before switching to another type. Analysis of territorial singing suggested that rate of switching song types is positively correlated with intensity of agonistic stimulation, where ‘agonistic’ signifies conflict-related. The song-switching hypothesis was tested with playback experiments which varied stimulus intensity in five different ways: (1) presence or absence of song stimuli; (2) addition of visual to auditory stimuli; (3) location of the song stimulus 20 m inside or outside territory; (4) nesting phases of the subjects; and (5) switching rate and rate of novel song type production of the playback (i.e. stimulus versatility). The subjects' switching rates and flight rates consistently increased with greater stimulation, although song rate tended to remain unaffected. The signalling of response intensity through adjustments in switching rate exemplifies how song repertoires function in agonistic communication.

An investigation of individual recognition by voice in female red-winged blackbirds

In order to determine if female Red-winged Blackbirds ( Agelaius phoeniceus) recognize each other as individuals on the basis of voice alone, playback experiments with 31 resident female redwings were performed. Female redwings sing two distinct song types. Fifteen females were exposed to Type 1 neighbour and Type 1 non-neighbour songs, and 16 females were exposed to Type 2 neighbour and Type 2 non-neighbour songs. Based on matched-pairs comparisons of the females' behavioural responses to the playback songs, female redwings do not appear to distinguish each other individually by voice. Loudspeaker placeement may be one confounding variable of significant importance in auditory individual recognition experiments.

Aggressive and Pair‐bond Maintenance Songs of Female Red‐winged Blackbirds (Agelaius pboeniceus)

AbstractFemale red‐winged blackbirds sing two distinct song types. Field observations and playback experiments indicate that Type 1 female song is sung chiefly in the presence of mates and probably functions in pair‐bond maintenance, while Type 2 song is sung chiefly in the presence of female conspecifics, and appears to be aggressive in nature.

Song repertoires and seasonal song in the yellowhammer, Emberiza citrinella

Songs were recorded from male yellowhammers, Emberiza citrinella, in England and West Germany. Sonagraphic analysis revealed three major types of song structure in both populations. Most males had a repertoire of two distinct song types, and sharing between individuals was extremely rare. Most song is produced late in the breeding season, and playback experiments confirmed that it is correlated with an increase in territorial aggression at this time. Some speculations are advanced concerning the origins and functions of song repertoires in the yellowhammer.

The Response of Swamp Sparrows To Acoustically Distinct Song Types

Abstract Male and femal swamp sparrows (Melospiza georgiana) were tested for differential reaction to four acoustically distinct swamp sparrow song types. We tested males by playing bouts of single song types from speakers placed on male territories. Males gave the same kinds of aggressive responses to each of the four song types, and there were no quantitative differences in the strengths of the responses to the different types. In the experiments with females, we played songs to captive female swamp sparrows previously treated with estradiol, and measured response in terms of copulation solicitation display. Females displayed in response to all four song types, and again there were no quantitative differences in the strength of response to the different types. We conclude that different swamp sparrow song types do not convey different messages to either male or female listeners. Although the identity of the particular song type presented was unimportant, the number of types presented was important, at least to females. Females responded more strongly overall to bouts of four song types than to bouts of single song types. This result occurred because females habituated to the repeated presentation of a single song type, and showed a recovery in response when song types were switched. We conclude that the ability to sing multiple song types may aid males in stimulating females to come into reproductive condition and then copulate.

Song Types in the Zebra FinchPoephila guttata castanotis1

A description of the general principles underlying Zebra Finch song is given in standardized terminology. Differences were looked for in songs produced in two different contexts: courtship song and undirected song. In more than 7 males (domesticated and wild ones), clear differences were found with respect to number of introductory elements, number of motifs, speed of performance, and rigidity in sequence, indicating two distinct song types. Motivational problems and the adaptive value are discussed.