Songs Of Species Research Articles

Bird song syntax: learned intraspecific variation is meaningful.

Song syntax, defined as orderly temporal arrangements of acoustic units within a bird song, is a conspicuous feature of the songs of many species of passerine birds. While syntactical features play a role in interspecific song recognition by males of many bird species, syntax variation within species and female responsiveness to song syntax have received little attention. This report demonstrates that differences in naturally occurring learned song syntax within a species whose syntax varies geographically are behaviorally salient to both male and female birds. The salience of culturally transmitted intraspecific differences in song syntax has implications for the process of conspecific song perception and may be involved in the regulation of genetic exchange between large populations of swamp sparrows (Melospiza georgiana).

Tropical Forest Bird Counts and the Effect of Sound Attenuation

Tropical Forest Bird Counts and the Effect of Sound Attenuation

Sexual differences in species recognition of avian song

Studies of species recognition in male birds have often identified features that are distinctive, invariant markers of a species song but which can be altered without altering male response1–4. Such results raise the question of why natural selection has favoured the retention of these features in the song. We propose that such features are favoured by selection because females use them in species recognition even though males do not. There are excellent theoretical grounds for expecting that males and females of the same species would differ in their means of species recognition, as required by this hypothesis. We report here that female red-winged blackbirds (Agelaius phoeniceus) discriminate against abnormal songs previously shown to be acceptable to males of this species. Similar sexual differences in species recognition may be expected in animals other than birds, and in recognition systems based on cues other than vocalizations.

The Role of Song Phonology and Syntax in Vocal Learning Preferences in the Song Sparrow, Melospiza melodia

AbstractAre young songbirds ready to learn virtually any song, or are they predisposed to learn songs of their own species? To explore this question tests were conducted on the equipotentiality of auditory song learning stimuli in the song sparrow. 23 males reared as nestlings were exposed to tape recordings of their own and other species songs in early life and subsequent song production was analyzed for imitations. Birds exposed to natural song sparrow songs, including their fathers', and equal numbers of swamp sparrow songs, strongly preferred conspecific songs. They neither favored nor eschewed paternal songs despite having had access to them for 6–10 days as nestlings. In three other experiments synthetic songs were used in which some properties were held constant and others were systematically varied. Birds were exposed to 1–4 segmented songs varying in phrase order, tempo and syllable number, each synthesized in two versions, one from conspecific and the other from heterospecific (swamp sparrow) song syllables. With one‐segmented songs (alien syntax) subjects favored conspecific over heterospecific syllable songs. Heterospecific syllables were rendered more acceptable by incorporation into two‐segmented trilled songs (more song sparrow‐like syntax). Heterogeneous summation of phonological and syntactical cues appeared to occur. There was also evidence of interaction between phonology and syntax. When another phrase type, the note complex, was added, in three‐ and four‐segmented songs, a preference for conspecific syllables reappeared. Heterospecific syllables may be more readily accepted as a trilled sequence than without repetition, as in a note‐complex. When phrase structure within four‐segmented songs was varied, birds favored patterns most like normal conspecific song. We conclude that there are innate learning preferences in the song sparrow, based on note and syllabic structure (phonology and syllabic syntax), and temporal organization of phrases (segmental syntax), differing from those of the closely related swamp sparrow, Melospiza georgiana, in which song syntax plays no role in learning preferences.

A Test of the Competition Hypothesis of Vocal Mimicry, Using Song Sparrow Imitation of White-Crowned Sparrow Song

A series of experiments were carried out to determine whether territorial male white-crowned sparrows could discriminate between playback of their own species song (the model) and the same song produced by a song sparrow (the mimic). Males responded strongly to both songs, and there were no significant differences in response measures between model and mimic. In contrast, most males showed no response to control song sparrow song, although two individuals showed clear interspecific responses. The results are discussed in relation to the competition hypothesis of vocal mimicry, which requires both deception of the model by the mimic and some evidence of interspecific aggression.

Feature Weighting in Species Song Recognition By the Field Sparrow (Spizella Pusilla)

Computer-modified songs were presented to wild territorial male field sparows to assess the relative importance of different acoustic features in species-song recognition. The features tested exhibited differing degrees of relative variability within field sparrow song. The experiments demonstrate that field sparrows arc sensitive to changes in song frequency, number and order of phrases, trill-note duration, note 'shape', and internote interval. Field sparrows appear to be 'tuned' to the normal range of varition in song features. Responses decreased significantly when features in the experimental songs were changed by two to three standard deviations relative to a control song. These results contrast with previous conclusions that birds only use 'invariant' features in species-song recognition. However, manipulations of invariant features, frequency and number of phrases, interfered with recognition more than did an equally-noticeable change to a variable feature, inter-note interval. The number of phrases in a song and the duration of trill notes appear to be equally important recognition cues. Thus, field sparrows integrate information from at least five different features in species song recognition, but give more weight to information from an invariant feature, song frequency, than they do to information from variable features.

The role of two-tone suppression in song coding by ventral cord neurones in the cricketTeleogryllus oceanicus (Le Guillou)

1. The calling, courtship and aggression songs ofT. oceanicus have distinctive temporal patterns but their spectral compositions are very similar: the carrier frequency occurs around 4.5 kHz and harmonics occur which extend above background noise level up to at least 40 kHz (Fig. 1). 2. Units were recorded in the cervical connectives which responded to sound frequencies over the range from 1 kHz to at least 40 kHz. The sensitivities of some of the high frequency units were comparable to, or exceeded, the sensitivities of the units responding to the carrier frequencies of the species songs (Fig. 2). 3. At the level of the neck connectives, units responding to the range from 10 kHz to 40 kHz could be divided, on the basis of their prothoracic morphology and physiology, into Through Neurones and Ascending Neurones. All the recorded neurones showed two-tone suppression effects but they varied in their degree of susceptibility to suppression. Frequencies in the range 4–5 kHz were most effective in producing suppression of the responses to high frequency tones (Figs. 5, 6). 4. The two identified Ascending Neurone types had similar morphologies in the prothoracic ganglion (Fig. 3). ANA showed tonic responses to pure tones in the frequency range from 10 kHz to 40 kHz. Below 10 kHz high intensity inhibition of the response occurred and the latency increased from about 15 ms for an 18 kHz tone pulse, to about 55 ms for a 4.5 kHz tone (Fig. 4). ANB responded with 1–3 spikes to stimuli in the frequency range from 7 kHz to 40 kHz. The response latency to an 18 kHz tone pulse was about 15 ms. No responses were obtained to 50 ms stimuli in the range from 2 kHz to 7 kHz (Fig. 6). However, considerable rebound activity was produced in response to 4.5 kHz stimuli of 200 ms or more; the latency of the rebound to 200 ms stimuli was about 400 ms (Fig. 6C). 5. ANA neurones responded to the syllables of the natural songs (Fig. 7), clearly coding the temporal patterns of the three songs. Cutting the contralateral leg nerve resulted in no detectable change in the neurone's response pattern. ANB neurones responded only during the intervals between chirps and during pauses within chirps. A long period of bursting activity occurred at the end of each song sequence (i.e. 3 chirps). This rebound activity may be the result of extreme inhibition caused by the CF of the songs (Fig. 7). 6. Synthesised natural songs (Fig. 1 E) with the correct temporal parameters but filled with 4.5 kHz alone, 18 kHz alone or a combination of 18 kHz and 4.5 kHz, were produced to investigate the role of two-tone suppression phenomena in song coding. The responses of both ANA and ANB (Fig. 8) showed the interaction of excitatory and inhibitory inputs to these units during the coding of the species songs. 7. Two-tone inhibition effects are advanced as the basic mechanism for the accurate coding of temporal characteristics in the songs ofT. oceanicus. Two different strategies for the recognition of species song types in crickets are advanced.

Geographic variation in the aerial song of the Short-billed Dowitcher (Aves, Scolopacidae)

The complex aerial song of the Short-billed Dowitcher (Limnodromus griseus) is described, and recordings from northern British Columbia (subspecies caurinus), northern Manitoba (hendersoni), and Labrador (griseus) are analyzed. The song is a stereotyped sequence of one to five units that are repeated rapidly and increase successively in duration. Each song unit consists of three readily distinguished element types (I, II, III), which form graded series occurring in fixed sequence. Song structure and element types are similar in all subspecies, but significant quantitative differences exist; the central subspecies (hendersoni) is clearly distinguished from the other two, in particular. These geographic differences are slight in comparison with primary song in many species of Oscines.

Song Features as Species Discriminants in American Warblers (Parulidae)

-Using multivariate discriminant analysis, we examined 337 songs of 19 species of wood warblers sympatric in New Brunswick, Canada. We divided the warblers into five overlapping groups of species based on habits and songs. Our hypothesis was that song features would be the most reliable at high noise levels or under conditions of poor transmission. Hence, we predicted that within most of these groups the songs would segregate highly on the basis of song features alone, as opposed to features of individual sounds or phones. In four of the groups the analysis correctly classified 84 to 95% of the songs on the basis of song features alone. In Group 5 (Yellow, Chestnut-sided, Redstart, Magnolia warblers), only 68% were correctly classified on the same basis. The addition of phone features to discrimination for this group increased the correct classification to 85%. In some groups the frequency modulation patterns of the phones are so simple that they contribute little to improved discriminations. The relative contributions of phones may be functionally related to the importance of possible competitors, the distance of the communication and other noise factors. and to the relative development of repertoires. An important function ascribed to bird song is the conveyance of information by which members of different species recognize their own kind. This role has been demonstrated in pairs, or, at most, small groups of species of wood warblers (Family Parulidae; Stein 1962, Ficken and Ficken 1967, 1969, Gill and Murray 1972) and other birds (Thielcke 196 1, Stein 1963, Catchpole 1973, Becker 1976). In such studies the songs were compared either subjectively by visual analysis of sonograms or by measuring a limited number of variables. Such comparisons are less satisfactory, however, when considering many species interacting in a natural environment. In that case, an objective method to compare quantifiable attributes of song is needed. In this paper, we examine relationships of songs among 19 sympatric species of warblers, using multiple discriminant analysis to objectively weigh differences among the songs. This multivariate technique is used both descriptively and to test an initial set of predictions on the structure of bird song necessary to achieve functional species recognition in species-rich habitats. To our knowledge, this approach has been used to only a limited extent (Sparling and Williams 1978, Brown and Lemon 1979). Two general types of variables characterize the structure of bird song. Songs of most species are generated from a limited set of basic sounds, continuous in time, which we call “phones.” A song may be simply the clustered repetition of a single phone, or it may have combinations and sub-groupings of phones. We use these two levels of features-phone and song-to define variables that are useful in any comparison of songs. Playback experiments on species recognition have shown that particular details of phones are sometimes essential to evoke a maximum degree of response (Falls 1963, Emlen 1972, Shiovitz 1975, Marler and Peters 1977, Shiovitz and Lemon 1980). Response to such detail is often limited even to members of the particular vocal community or dialect (Lemon 1969, Milligan and Verner 197 1). Sounds are often distorted, however, through masking, attenuation and related phenomena, depending on the presence of other species’ songs, distance, variable densities of air, etc. (Wiley and Richards 1978, Lemon et al. 198 1, Richards 198 1). Consequently, overall features of song, as opposed to precise details of phones, should be expected also to contribute strongly to species recognition in natural environments. For example, among certain warblers, the species differ by song characteristics such as range and mode of frequency, as well as by groupings of phones (Ficken and Ficken 1962, Lemon et al. 198 1). Because the problems of distortion should apply to details of phones more than to more general features of timing and sequence, we

Plants as transmission channels for insect vibrational songs

The vibrational songs of several species of cydnid bugs and ‘small cicadas’ (leafhoppers and planthoppers) living on various types of plants are recorded by means of laser vibrometry. The recorded vibrational songs are analysed with respect to amplitude, frequency spectrum and structure in the time domain (Figs. 2–5).

Species song discrimination in adult female song and swamp sparrows

Six female song sparrows ( Melospiza melodia) and six female swamp sparrows ( Melospiza georgiana) were treated with oestradiol, and their response to song measured by frequency and intensity of copulation-solicitation display. Test stimuli were synthetic songs composed of either song sparrow or swamp sparrow syllables assembled in either song-sparrow-like or swamp-sparrow-like temporal patterns. Female song sparrows responded preferentially to songs containing their own species' syllables and to songs containing their own species' temporal patterns. Swamp sparrows were also sensitive to both syllable type and temporal, pattern, in contrast to male swamp sparrows, which show no preference for swamp sparrow temporal patterns.

Species song discrimination in choice experiments with territorial male swamp and song sparrows

Playbacks of synthetic and normal songs were used to determine what song parameters are important to species song recognition by territorial male swamp sparrows ( Melospiza georgiana) and song sparrows ( Melospiza melodia). Syllable morphology influences the discrimination of conspecific song from song sparrow song in adult swamp sparrows, but temporal pattern does not; this result duplicates that found in studies of song learning of the young in this species. Species song recognition is influenced by both syllable morphology and temporal pattern in adult song sparrows, in contrast to the situation in young sparrows, which seem not to distinguish their own species' song from that of swamp sparrows on either cue.

Sexual Selection and the Evolution of Complex Songs Among European Warblers of the Genus Acr Ocephal Us

AbstractAn attempt has been made to explain why the songs of Acrocephalus warblers have become so complex during their evolution. A considerable body of evidence has implicated sexual selection, and two predictions from sexual selection theory have been tested. First, males with more complex songs should attract females for pairing before their rivals with simpler songs. This prediction has been confirmed, when a strong inverse correlation between syllable repertoire size (song complexity) and pairing date (female choice) was obtained in a population of sedge warblers. No significant correlation was obtained between male arrival date and pairing date. Assuming that the first (usually older) males back should select the best territories, then territory quality appeared to have little or no significant effect upon female choice. The second prediction tested was that due to increased sexual selection pressure, males of polygynous species should have evolved more comples songs than males of monogamous species. Of the six common European Acrocephalus species studied, four are monogamous and two polygynous. The prediction was not upheld, as the four monogamous species had long, complex and variable songs, and the two polygynous species had shorter, simpler and less variable songs. The explanation for this apparent paradox can be found in the different relationships between female choice, feeding ecology and parental investment in monogamous or polygynous Acrocephalus species. In polygynous species, a female must ensure the territory contains enough resources to enable her to feed the young and should base her choice primarily upon territory quality. In monogamous species, a female must select a male who will help her to feed the young, and should base her choice more directly upon male quality. The songs of polygynous species have therefore evolved primarily through indirect (intrasexual) sexual selection pressure, which has produced shorter, simpler and more stereotyped songs more suited to male-male interactions and a territorial function. The songs of monogamous species have evolved primarily through direct (intersexual) selection pressure, which has produced the long, complex and variable songs which females find more attractive.

Geographical Variation in the Song of the Great Tit (Parus major) in Relation to Ecological Factors

(1) We recorded the territorial songs of great tits at ten different geographically separated sites. Five of the sites were in dense deciduous or coniferous forest, and five in open woodland, parkland or hedgerows. (2) Forest birds from England, Poland, Sweden, Norway and Morocco had songs with a lower maximum frequency, narrower frequency range and fewer notes per phrase than woodland birds from England, Iran, Greece, Spain and Morocco. (3) We also measured acoustic attenuation for each habitat type; and for each study site we noted; body size of the birds, tree density, territory size, song of other species, song perch height, temperature and humidity. (4) We suggest that the differences in song between habitats, and striking similarities of songs from the same habitat type are at least in part related to differences in acoustic attenuation and territory size. Birds living in dense forests have to broadcast songs through more vegetation and over greater distances than do woodland birds. (5) We conclude that differences between habitats in climate, body size, perch height, and acoustic competition from other species are unimiportant in accounting for the observed differences in song. (6) If it is accepted that forest songs are better suited for long distance transmission, we cannot explain why woodland birds use less well designed songs, although we offer some suggestions.

Acoustic Competition Between the Song of the Wren (Troglodytes Troglodytes) and the Songs of Other Species

The efficiency of the Wren's song may be impaired by certain background noises. Natural noises, such as those emitted by sympatric birds decrease the receiving Wren's alertness (Table 1). This phenomenon has no compensating process and is probably rather detrimental to communication between Wrens in an acoustically rich natural environment. When the Wren's song is masked with artificially made signals there are no serious ethological consequences (Table 2) as masking is seldom complete, and decrease in the received information is largely compensated by the song's inherent redundancy. The precise requirements for a mask to hinder communication efficiency are described. They are so stringent that the odds are overwhelmingly against their being ever met with in nature.

Acoustic Competition Between the Song of the Wren (Troglodytes Troglodytes) and the Songs of Other Species

The efficiency of the Wren's song may be impaired by certain background noises. Natural noises, such as those emitted by sympatric birds decrease the receiving Wren's alertness (Table 1). This phenomenon has no compensating process and is probably rather detrimental to communication between Wrens in an acoustically rich natural environment. When the Wren's song is masked with artificially made signals there are no serious ethological consequences (Table 2) as masking is seldom complete, and decrease in the received information is largely compensated by the song's inherent redundancy. The precise requirements for a mask to hinder communication efficiency are described. They are so stringent that the odds are overwhelmingly against their being ever met with in nature.

Aggressive responses of male sedge warblers ( Acrocephalus schoenobaenus) to playback of species song and sympatric species song, before and after pairing

Playback experiments with species song elicited strong levels of aggression from unpaired sedge warbler males in territory. After pairing, although a significant decrease in aggression was detected it was sufficient to maintain territory throughout the breeding season. As males ceased to sing upon pairing, it seems unlikely that habituation to song was responsible for the decrease in aggression. Experiments with sympatric reed warbler song confirmed the existence of interspecific aggression. In unpaired males the lower level of interspecific aggression was similar to that in paired males in response to species song. Interspecific aggression did not show a significant decrease after pairing, responses were much more variable and possibly related to the individual's particular territorial situations both past and present.

Species identification in the North American cowbird: appropriate responses to abnormal song.

Female cowbirds raised in auditory isolated from males responded to the songs of male cowbirds with copulatory postures. The songs of males reared in isolated were more effective in eliciting the posture than the songs of normally reared males. The females did not respond to the songs of other species. These results indicate one mechanism of species identification for this parasitic species.

Species Specificity and Individual Variation in the Songs of the Brown Thrasher (Toxostoma Rufum) and Catbird (Dumetella Carolinensis)

Abstract The Brown Thrasher, like his fellow mimic thrushes, sings a highly variable song. So variable are the individual notes of the song that field identification on the basis of a single burst of song is hazardous. Reliable field identification traditionally has depended on the number of utterances of each sound rather than on the note qualities of the sounds themselves: Brown Thrashers (Toxostoma rufum) seem to utter sounds in pairs, whereas Catbirds (Dumetella carolinensis) do not repeat sound and Mockingbirds (Mimus polyglottos) repeat each sound several times. The purposes of this study were two: first, to establish that the thrasher does in fact distinguish his own song from that of the other mimic thrushes. Second, to develop evidence of the cues used to make the discrimination. Two techniques were used, playback trials and song recording analysis. In playback trials, Brown Thrashers were played samples of Brown Thrasher, Catbird, and Mockingbird song. Some samples were natural recordings and some were artificial samples in which the numerical properties of the songs had been distorted. For comparison purposes, an analogous set of recordings was played to Catbirds. The song recording analyses entailed sonagraphic reproduction of extensive segments of the songs of four thrashers and a careful study of the form, temporal properties, and statistical characteristics of the sounds thus represented. 1) Brown Thrashers clearly discriminate Brown Thrasher song from Catbird song and the basis of the discrimination is the number of utterances of each sound. Thrashers respond more vigorously to Brown Thrasher song than to Catbird song, to doubled Catbird song than to normal Catbird song, and to normal thrasher song than to halved thrasher song. 2) The results do not show that thrashers discriminate their own songs from Mockingbird song. Thrashers do respond more vigorously to normal Brown Thrasher song than to artificially lengthened Brown Thrasher song, but do not respond more vigorously to normal Brown Thrasher song than to normal Mockingbird song nor do they respond more vigorously to shortened Mockingbird song than they do to the normal form. 3) Catbirds can discriminate their songs from the songs of the other mimic thrushes, but they do not appear to make this discrimination on the basis of number. Catbirds respond more vigorously to the normal songs of their own species than to normal songs of the other two species but they do not respond more vigorously to shortened versions of the other species songs nor less vigorously to lengthened versions of their own song. 4) The sonagraphic analysis of thrasher song produced paradoxical results. Despite the importance of the two-ness in the field identification of thrasher song, no reliable property of two-ness was discernible in the sonagrams. Brown Thrashers did not reliably repeat each utterance nor pair utterances. In fact, the numerical properties of their songs, like all of the properties observed, overlapped extensively with the numerical properties of the other two mimic thrushes. However, these properties, like other properties studied, did differ on the average between the song of the thrasher and the song of the other mimic thrushes. The results suggest that the search for a single parameter that immediately distinguishes the songs of the species may be misguided. The songs of the mimic thrushes may differ only in the average value of several parameters and the birds like human observers in the field may have to hear several units of song before they can make a definite species identification. Despite the inefficiency of this process, the birds sing so rapidly and constantly that species identification of their songs would take no longer than species identification of slower but more consistent song.

Songs of Song Sparrows: Reactions of Males to Songs of Different Localities

Song in birds is generally associated with territorial defense, reproduction, and maintenance of the pair bond (Thorpe 1961; Marler and Hamilton 1966). Since the songs of most species are distinctive even to the human ear, it has long been supposed that they aid in the reproductive isolation of one species from another (Marler 1960). The males of many species have been found to react to playback of a song of their own species in a manner typically including vocalizations, movement toward the sound source, and visual displays. Other species' songs do not elicit such reactions (Dilger 1956; Thielcke 1962; Lanyon 1963; Stein 1963; Gill and Lanyon 1964; Ficken and Ficken 1967; Lemon and Herzog 1969; Thompson 1969; Schubert 1971; Emlen 1972). As well as the differences between species, dialects or consistent differences between nearby populations may occur within the songs of one species. Dialects have been shown to exist in a wide variety of songbirds, including the Chaffinch (Fringilla coelebs) (Marler 1952), Short-toed Tree Creeper (Certhia brachydactyla) (Thielcke 1961), Great Tit (Parus major) (Gompertz 1961), Whitecrowned Sparrow (Zonotrichia leucophrys) (Marler and Tamura 1962), Mistle Thrush (Turdus viscivorus) (Isaac and Marler 1963), Cardinal (Cardinalis cardinalis) (Lemon 1966), Pyrrhuloxia (Pyrrhuloxia sinuata) (Lemon and Herzog 1969), Chingolo (Zonotrichia capensis) (Nottebohm 1969), Indian Hill Mynah (Gracula religiosa) (Bertram 1970), Rufous-sided Towhee (Pipilo erythrophthalmus) (Kroodsma 1971), and Vesper Sparrow (Pooecetes gramineus) (Kroodsma 1972). Behavioral responses to dialects have not been widely studied, but in the species which have been investigated, responses were stronger to songs of the birds' own dialects, as in the Cardinal (Lemon 1967), the Indian Hill Mynah (Bertram 1970), and the Whitecrowned Sparrow (Milligan and Verner 1971). Each male Song Sparrow (Melospiza melodia) possesses a repertoire of several different song patterns, each of which is repeated several times before another is begun. Although neighbo ing birds rarely have entire song patterns which are identical to one another, they usually have some elements within the patterns in common. Shared elements have been noted for birds in southern Quebec (Harris d Lemon 1972) and in Maine (Borror 1965), although Mulligan (1966) makes no such claims for birds in California.