Song characterization in the spectacled warbler (Sylvia conspicillata): a circum-Mediterranean species with a complex song structure

The spectacled warbler (Sylvia conspicillata) is a small passerine with a patchy distribution throughout the circum-Mediterranean region, including the North Atlantic archipelagos of Madeira, Canary Islands and Cape Verde. Here we characterize the species song structure on the island of Fuerteventura, quantifying repertoire size, inter- and intra-individual spectrographic variation, to determine whether acoustic variation occurred within an island population. Male song display was organized in song bouts of a variable number of song phrases, which in turn were made up of 4–69 syllables. We classified syllable types to derive a measure of repertoire size (number of different syllables) per song bout, and then used rarefaction methods to calculate the estimated repertoire size for our population of males. Three categories of song bout length were considered in analyses: short song bouts of 10 phrases, average bouts of 19 phrases and long bouts of ≥ 29 phrases. The observed and estimated repertoire size per male (between 43 and 126 syllables per male) increased with song bout duration, although the relationship was not significant for the estimated values. To test whether songs could be individually specific, we measured 11 spectrotemporal parameters of the song. A discriminant analysis using these variables performed poorly in classifying songs to the individuals that uttered them, but we found less variation in the individual than in the population for three out of the 11 variables. These individually specific variables, involving the first or the most common syllable of the song, the trill, were the duration of the first syllable of the phrase, the duration and the dominant frequency of the trill syllable. Our study emphasizes the complexity of spectacled warbler songs, in which males continuously add novel syllables over the entire song bout. This complexity appears to be determined by individual innovation capabilities rather than by the behaviour of copying neighbour repertoires, since songs of close birds were not more similar than songs from far-away territories.     

10种鸣禽控制鸣啭神经核团大小与鸣唱复杂性的相关性

为进一步揭示鸣禽鸣唱行为的神经生物学机制 ,本实验先对 8个科 10种鸣禽的鸣唱行为进行了观察和录音 ,并借助声谱软件分析了每种鸣禽的鸣唱复杂性。鸣唱语句复杂性的评价指标包括 :短语总数、每个短语中所含的平均音节数及音节种类数、所有短语的总音节数及音节种类数、最长短语的音节数及音节种类数。然后 ,测定了前脑三个鸣啭学习控制核团和一个与发声无关的视觉参考核团体积 ,分析了鸣唱语句复杂性和这些核团大小间的相关关系。结果表明 :1)HVC和HVC/Rt与 7种鸣唱语句复杂性指标无关 ;RA和RA/Rt与总音节种类数相关 ;AreaX与总音节数及音节种类数相关 ;2 )HVC/RA和HVC/X比值与多个鸣唱语句复杂性指标相关。结果提示 :鸣禽鸣唱复杂性不同特征可能受不同神经控制     

Species Recognition by Song in the Veery (Catharus fuscescens: Aves)

Territorial male veeries (Catharus fuscescens) were presented with three series of reorganised songs to determine the functional properties of song structure. Songs consist of three parts: a low frequency initial phrase, a higher frequency middle phrase, and again a lower frequency end phrase. The latter two consist of vibrato syllables. Three series of experiments were performed, using various combinations of song syllables. In Series I, songs consisted of repetitions of a single syllable, one from each part of the song. Veeries responded to syllables from the middle and end phrases as to normal songs, both in localisation and in vocal responses. However, they showed little localisation and vocalisation responses to the introductory syllables. In Series II and III, veeries responded significantly more to songs in which syllables from the middle and end phrases were presented in proper sequence, rather than not. The minimum requirements for intraspecific recognition were determined in relation to the number and order of syllables in the song.     

Versatility and Stereotypy of Free-Tailed Bat Songs

In mammals, complex songs are uncommon and few studies have examined song composition or the order of elements in songs, particularly with respect to regional and individual variation. In this study we examine how syllables and phrases are ordered and combined, ie “syntax”, of the song of Tadarida brasiliensis, the Brazilian free-tailed bat. Specifically, we test whether phrase and song composition differ among individuals and between two regions, we determine variability across renditions within individuals, and test whether phrases are randomly ordered and combined. We report three major findings. First, song phrases were highly stereotyped across two regions, so much so that some songs from the two colonies were almost indistinguishable. All males produced songs with the same four types of syllables and the same three types of phrases. Second, we found that although song construction was similar across regions, the number of syllables within phrases, and the number and order of phrases in songs varied greatly within and among individuals. Last, we determined that phrase order, although diverse, deviated from random models. We found broad scale phrase-order rules and certain higher order combinations that were highly preferred. We conclude that free-tailed bat songs are composed of highly stereotyped phrases hierarchically organized by a common set of syntactical rules. However, within global species-specific patterns, songs male free-tailed bats dynamically vary syllable number, phrase order, and phrase repetitions across song renditions.     

Song Learning in the Anna Hummingbird (Calypte anna)

Songs of wild male Anna hummingbirds (Calypte anna) consist of syllables grouped into phrases. Nearest neighbors tend to share similar syllable types, rhythms and syntax. Songs from different localities contain different syllable types, syntax and repetition indices. A male raised by hand in isolation produced a song consisting of highly variable syllable types of a wide frequency range. The song was simple in structure, and syllables were not grouped into phrases. Three males raised by hand as a group sang songs containing two stereotyped syllable types sung in alternating sequence and without phrase structure. These three males shared syllable types and syntax. The data from our study indicate that despite its relatively simple syrinx the Anna hummingbird learns syllable types, frequency, rhythm and syntax (as do oscines with their more complex syringes) during the song development process.     

10种鸣禽鸣唱复杂性与发声核团体积的聚类分析

选用捕自野外和人工繁殖的10种雄性成鸟(一年龄以上)作为实验材料。当鸟适应环境后录音,用VS-99语音工作站软件进行声谱分析。鸣唱的复杂性采用语句短语总数、短语的音节数之和、短语的音节种类数之和、每个短语中所含的平均音节数、每个短语中所含的平均音节种类数、每种鸣禽最长短语的音节数和最长短语的音节种类数7项指标表示。然后测定前脑的上纹状体腹侧尾端(HVC)、古纹状体粗核(RA)以及嗅叶的X核(Areax)3个主要鸣唱控制核团的体积。最后分别对10种鸣禽3个发声控制核团体积和鸣唱复杂性的7项指标进行聚类分析。10种鸣禽的7项指标值相差较大,即使同一科也如此。蒙古百灵的3种核团体积比值均最大,其次是金丝雀和黄喉鹉。10种鸣禽鸣唱语句复杂性的7个指标和3种核团体积聚类分析树形图显示的结果各不相同;仅RA和Areax核团体积的树形图显示蒙古百灵远离其他9种鸣禽,与现代分类学和DNA分析得到的进化树一致。     

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

Are 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.     

Inferring performance in the songs of dark-eyed juncos (Junco hyemalis)

Within bird species, songs differ in their attractiveness tofemales or effectiveness in male–male interactions. Somesongs are more difficult to sing than others, and receiversmay use a singer's performance of difficult songs as a meansfor evaluating the quality of the singer. The concept of songperformance aims at quantifying how physiologically demandingare different songs. Using variation between song types of dark-eyedjuncos, Junco hyemalis, we show that some song traits tradeoff with costly aspects of song output—short intervalsbetween syllables or loud sound amplitude—suggesting thatthose traits are difficult to sing. First, after controllingfor other traits, long syllables require longer intervals forrecovery. This supports the idea that a measure of "respiratoryperformance" could be based on the relative lengths of syllablesand intervals. Second, some syllable traits trade off stronglywith sound amplitude, suggesting that these traits may be difficultto sing at high amplitudes. The ratio of frequency bandwidthand trill rate has been used to infer performance in other birdspecies, but we found no evidence that frequency bandwidth tradesoff with any aspect of song output in the junco. The negativeassociation of bandwidth with trill rate may instead be a passiveconsequence of syllable length, with longer syllables randomlyaccumulating frequency modulation. We conclude that bird receiversmay best evaluate how well a song is performed if they integratemultiple cues and discuss how researchers may similarly devisemeasures of song performance.     

Cultural Evolution of Puget Sound White-Crowned Sparrow Song Dialects

The songs of male Puget Sound white‐crowned sparrows currently form about 12 dialects along the Pacific Northwest coast. In his survey of 1970, Baptista (Condor 1977; 79: 356–370) defined six of the dialects based on the song's terminal trill because most males at each locality shared the simple syllables (SSs) in this trill. The complex syllables (CSs) in the song's introduction varied among males at a locality, and were often shared among localities. From 1997 to 2004 we revisited nine of the sites Baptista studied to determine whether the SSs and CSs had changed over the 30‐yr interval. Using Baptista's catalogs of SS and CS types as bases for comparison, we found that the relative proportions of CS types changed significantly more over time than did the proportions of SS types. These results suggest that SSs and CSs evolve independently. Observations were also made on the developmental mechanisms that either produce diversity or maintain uniformity in song phrases. In a survey of 670 field‐recorded songs, unique improvizations occurred significantly more often in CSs than in SSs. In a laboratory experiment using hand‐reared males and multiple song tutors, males were significantly more accurate in imitating SSs than CSs. In choosing their final song to keep from their overproduced repertoire, yearling males tended to retain the song type that matched the SSs in the song played back to them. We conclude by discussing how differences in the functions served by these two song phrases may have led to their different rates of cultural evolution.     

Experimental evidence that distinct song phrases in the Grey‐cheeked Fulvetta Alcippe morrisonia permit species and local dialect recognition

Birds with small song repertoires have a limited number of song types which may serve multiple functions. The Grey‐cheeked Fulvetta Alcippe morrisonia is a non‐migratory species of lowland forests in Taiwan. Its song consists of two distinct phrases: a whistled phrase and a harmonic one. Each individual usually sings only one type of whistled phrase, and the geographical patterns of songs can be distinguished by the motif of this phrase. We proposed a dual adaptation hypothesis for the functions of these two phrases. Playback experiments including six sound stimuli (familiar whistled phrases, familiar harmonic phrases familiar complete songs, foreign whistled phrases, foreign harmonic phrases and foreign complete songs) were conducted at 12 sites in the Shoushan Nature Park of Kaohsiung, Taiwan. Grey‐cheeked Fulvettas came closer to the playback speaker and increased counter‐singing more in response to the familiar whistled phrase (local dialect) than to a foreign whistled phrase (distant dialect). However, birds responded equally to the playback of harmonic stimuli from familiar and foreign sources. We suggest that in this species, whistled phrases are used for local recognition and harmonic phrases are used for species recognition in short‐range communication.     

Airflow and pressure during canary song: direct evidence for mini-breaths

Summary Male canaries (Serinus canaria) produce songs of long duration compared to the normal respiratory cycle. Each phrase in a song contains repetitions of a particular song syllable, with repetition rates for different syllables ranging from 3 to 35 notes/s. We measured tracheal airflow and air sac pressure in order to investigate respiratory dynamics during song.Song syllables (11–280 ms) are always accompanied by expiratory tracheal airflow. The silent intervals (15–90 ms) between successive syllables are accompanied by inspiration, except for a few phrases where airflow ceases instead of reversing. Thus, the mini-breath respiratory pattern is used most often by the five birds studied and pulsatile expiration is used only occasionally.Songs and phrases accompanied by minibreaths were of longer duration than those accompanied by pulsatile expiration, presumably because the animal's finite vital capacity is not a limiting factor when the volume of air expired for one note is replaced by inspiration prior to the next. Pulsatile expiration was used for only a few syllable types from one bird that were produced at higher repetition rates than syllables accompanied by mini-breaths. We suggest that male canaries switch to pulsatile expiration only when the syllable repetition rate is too high (greater than about 30 Hz) for them to achieve mini-breaths.Changes in syringeal configuration that may accompany song are discussed, based on the assumption that changes in the ratio of subsyringeal (air sac) pressure to tracheal flow rate reflect changes in syringeal resistance.     

斑背大尾莺繁殖期鸣声行为分析

2009年5-7月,在辽宁双台河口保护区录制了20只繁殖期斑背大尾莺雄性个体的鸣声.根据行为特征,该鸟鸣声定义为3种鸣声类型:求偶炫耀鸣唱、报警声和联络声.利用Wavesurfer软件对20只斑背大尾莺雄性个体543个鸣声的句子持续时间、句子音节个数、音节持续时间、音节间隔时间等4个参数进行分析测量,发现求偶炫耀鸣唱由节奏逐渐加快的前部句子和音节组成复杂的主体部两个句子组成; 报警声和联络声的句子均由单音节组成.音节类型总数为38种,其中包括前部句子的音节类型6种.采用单因素方差分析(one-way ANOVA)对求偶炫耀鸣唱的4个参数进行差异性检验发现,不同个体的各个参数均呈极显著差异(P<0.01).     

Directional female preference for an exaggerated male trait in canary (Serinus canaria) song

Motor constraints on vocal production impose a trade-off between trill rate and frequency bandwidth within birdsong. We tested whether domesticated canary (Serinus canaria) females, reared either in acoustic isolation or in aviary conditions, had a preference for broad bandwidth songs with artificially increased syllable rates. The copulation solicitation display (CSD) was used as an index of female preference. As predicted, both naive and experienced females were especially responsive to syllables with a broad bandwidth emitted at an artificially increased rate. Female preference for supernormal stimuli provide support for the honest-signalling hypothesis and our results are consistent with recent findings indicating that production of song phrases maximizing both bandwidth and syllable rate may be a reliable indicator of male physical or behavioural qualities. We suggest that female preference for vocal emissions, which simultaneously maximize these two parameters, could be a widespread pattern within songbirds.     

Male Song Stimulation of Female Reproduction in Canaries: Features Relevant to Sexual Displays are not Relevant to Nest-building or Egg-laying

Recent studies conducted in our laboratory have demonstrated that a special type of song phrase (‘sexy’ phrases) containing bipartite syllables composed of abrupt frequency falls and short silences stimulate female canaries to solicit for copulation. The study was undertaken to determine whether sexy phrases also facilitated other aspects of the reproductive activity of the female canary, namely, nest-building and egg-laying. During the first experiment, we studied the effect of sexy and non-sexy songs on copulation solicitation displays in 1-year-old females without reproductive experience and in mature females with previous reproductive experience. We confirmed that sexy songs elicited more sexual responses than did non-sexy songs in yearlings and in mature females. During the second experiment, we studied the effect of male songs on nest-building activities and egg-laying in 1-year-old inexperienced females, and in mature, experienced females. The songs of conspecific males significantly triggered and increased nest-building behaviour in female canaries whatever their age or reproductive experience. In contrast, song effects on egg-laying were only found in young females. One-year-old inexperienced females exposed to sexy or non-sexy songs laid more eggs and laid earlier than did 1-year-old inexperienced controls; no such differences were observed in mature, experienced females. The efficiency of songs in promoting nest-building or egg-laying appeared to be unrelated to their efficiency in eliciting sexual responses. No difference was found between females exposed to sexy songs and females exposed to non-sexy songs; differences were only found between control and the two groups of song-exposed females. This result demands further experiments in order to determine whether other song phrase types may account for the stimulating effects of male song on female nest-building and egg-laying.     

Advertising vocalization of the clamorous reed warbler (<Emphasis Type="Italic">Acrocephalus stentoreus</Emphasis>, Sylviidae)

The advertising vocalization of the clamorous reed warbler, one of the least studied representatives of the genus in the Palearctic, has been analyzed. In this species, advertising vocalization consists of compact acoustic constructs (songs) separated by pauses. The duration of songs (median 3.6 s) and pauses (median 2.9 s) varies only slightly. Each song consists of three to four different or identical syllables. Syllables (stereotyped acoustic constructs) consist of two to four notes. Each male has from 5 to 25 syllables in his repertoire. A sharp contrast between low-frequency and high-frequency notes and strict sequence of these notes in syllables (low-frequency notes come first, then follow high-frequency notes) are characteristic of this song. All types of syllables in the song of a given male can be divided into two groups: initiator syllables and other syllables. Initiator syllables most often occur at the beginning, while others occur in the middle or at the end of the song. Stable links between syllables have been revealed: the majority of them occur in the song together with certain syllables (one or two) of other types. The whole range of songs of each individual can be divided into several classes. A certain type of initiator syllable and a certain set of subsequent syllables are characteristic of each class. However, the variability of songs within each class is quite high. Modes of immediate and eventual variety alternate in the sequence of songs from different classes. Thus, 47.4% of songs are followed by a song from the same class (eventual variety), while 52.6% of songs are followed by a song from a different class (immediate variety). The advertising vocalization of the clamorous reed warbler is compared with that of other representatives of the genus Acrocephalus.     

Physically Challenging Song Traits,Male Quality,and Reproductive Success in House Wrens

Physically challenging signals are likely to honestly indicate signaler quality. In trilled bird song two physically challenging parameters are vocal deviation (the speed of sound frequency modulation) and trill consistency (how precisely syllables are repeated). As predicted, in several species, they correlate with male quality, are preferred by females, and/or function in male-male signaling. Species may experience different selective pressures on their songs, however; for instance, there may be opposing selection between song complexity and song performance difficulty, such that in species where song complexity is strongly selected, there may not be strong selection on performance-based traits. I tested whether vocal deviation and trill consistency are signals of male quality in house wrens (Troglodytes aedon), a species with complex song structure. Males’ singing ability did not correlate with male quality, except that older males sang with higher trill consistency, and males with more consistent trills responded more aggressively to playback (although a previous study found no effect of stimulus trill consistency on males’ responses to playback). Males singing more challenging songs did not gain in polygyny, extra-pair paternity, or annual reproductive success. Moreover, none of the standard male quality measures I investigated correlated with mating or reproductive success. I conclude that vocal deviation and trill consistency do not signal male quality in this species.     

Behavioral sterility of hybrid males in acoustically communicating grasshoppers (Acrididae,Gomphocerinae)

The effectiveness of hybridization barriers determines whether two species remain reproductively isolated when their populations come into contact. We investigated acoustic mating signals and associated leg movements responsible for song creation of hybrids between the grasshopper species Chorthippus biguttulus and C. brunneus to study whether and how songs of male hybrids contribute to reproductive isolation between these sympatrically occurring species. Songs of F1, F2, and backcross hybrids were intermediate between those of both parental species in terms phrase number and duration. In contrast, species-specific syllable structure within phrases was largely lost in hybrids and was produced, if at all, in an irregular and imperfect manner. These divergences in inheritance of different song parameters are likely the result of incompatibility of neuronal networks that control stridulatory leg movements in hybrids. It is highly probable that songs of hybrid males are unattractive to females of either parental species because they are intermediate in terms of phrase duration and lack a clear syllable structure. Males of various hybrid types (F1, F2, and backcrosses) are behaviorally sterile because their songs fail to attract mates.     

What exactly is ‘local song’ in a population of ortolan buntings with a common dialect?

Previous studies have shown that ortolan buntings (Emberiza hortulana) exhibit apparent dialect variation. Neighbouring males typically share the same final phrase of a simple two-part song. Consequently, the final phrase was considered to be the dialect cue important for discriminating between males from a local population and strangers. Recently, it was shown that in an isolated and fragmented population of the ortolan buntings in Norway there was no local dialect in the above-mentioned sense. Norwegian males often had song types with different final phrases in their repertoire, and had larger repertoires and a lower level of song type sharing than in other populations. It was experimentally revealed that only local songs (L) evoked a strong response in Norwegian males, while these birds did not respond strongly to foreign (F) or hybrid songs composed of local and foreign initial and final phrases in any composition (i.e. both FL and LF songs). These results suggest that, in the Norwegian population, the final phrase of the song is not a sufficient cue for local song dialect recognition. This paper is a further study in which we tested the response of the ortolan bunting males to L, F, FL and LF songs in a typical continuous population (in Poland) in which males share the same single final phrase, i.e. have a common dialect. We found that ortolan bunting males in Poland responded with similar strength to L, FL and LF songs. The majority of males did not respond as strongly to playback of only F songs. Our results suggest that a common final phrase for a population should not be treated as the only signal of ‘locality’. Our results show clear asymmetry in response to hybrid songs with non-local phrases in different populations.