Song Patterns Research Articles

Forebrain lesions disrupt development but not maintenance of song in passerine birds.

The magnocellular nucleus of the anterior neostriatum is a forebrain nucleus of passerine birds that accumulates testosterone and makes monosynaptic connections with other telencephalic nuclei that control song production in adult birds. Lesions in the magnocellular nucleus disrupted song development in juvenile male zebra finches but did not affect maintenance of stable song patterns by adult birds. These results represent an instance in which lesions of a discrete brain region during only a restricted phase in the development of a learned behavior cause permanent impairment. Because cells of the magnocellular nucleus accumulate androgens these findings raise the possibility that this learning is mediated by hormones.

Inheritance of Song Parameters in the Gibbon Song, Analysed in 2 Hybrid Gibbons (Hylobates pileatus × H. lar)

The song of a male and a female hybrid gibbon (Hylobates pileatus × H. lar) is described. Comparison with the song of both parental species revealed that at least some of the hybrid’s song characteristics were inherited. Although several studies have tentatively suggested a genetical determination of gibbon song patterns, there have been no previous analyses of gibbon singing behaviour which conclusively documented this phenomenon. Attention is drawn to similarities between the song of the hybrids and gibbon species other than the parental ones, and their significance is considered.

Circadian control of singing in crickets: Two different pacemakers for early-evening and before-dawn activity

(1) Under LD 12:12 and constant temperature, calling song patterns of the Australian Field Cricket Teleogryllus commodus were frequently divided into two more or less distinct activity components. The first began 1–3 h before the L D -transition and ended with the sudden lights-off, whereas the second was restricted mainly to the second half of the night. In subsequent continuous light (LL) the circadian activity pattern was usually a unimodal band. Its onset slope was always a continuation of the first onsets in the preceding LD-cycle. In those cases where shortly after the LD LL transition the rhythm split into two components, both corresponded to those in LD. (2) In “atypical” LD-aatterns only the second component appeared during the late night. In such cases, the onset slope of the subsequent free-running rhythm did not start at the preceding LD-entrained onsets, but was advanced by several hours. (3) In free-running rhythms the mean value of the onset slopes ( τ o = 25.1 ± 0.07 h ) did not differ significantly from that of the end slopes ( τ e = 25.0 ± 0.07 h ). However, in individual activity patterns, simultaneous differences in onset and end slopes of up to 0.7 h were found. τ o- and τ e-values recorded directly after the LD LL -transition did not correlate with the preceding phase angle difference between the entrained activity and the zeitgeber. (4) Under constant conditions after-effects such as spontaneous period changes and phase shifts in the slopes of activity onset and/or end occurred mainly between five and 20 days after the LD LL -transition . (5) Period changes and phase delays in the onset and end slopes were also found when crickets were exposed to low temperature pulses (2 ± 2°C, 2h duration). Following the cold treatment both period changes and phase shifts in the onset slope frequently differed from those in the end slope. (6) The results are consistent with a concept of two activity components controlled by weakly coupled circadian pacemakers. This is clearly evident in split rhythms but is also true for unimodal patterns. Normally the two components partly overlap and their existence is concealed in the undivided activity band. They are only revealed in unimodal patterns if individual oscillatory properties such as different period lengths or phase shifts appear in the onset or the end slope.

Vocal learning in White-crowned Sparrows: sensitive phase and song dialects

In a laboratory song tutoring experiment, eight male White-crowned Sparrows learned their natal song dialect, presented to them at 10 to 50 days of age, in preference to an alien dialect, presented to them from 51 to 90 days of age; two males learned the alien dialect, one developed a hybrid song, and one a simple song lacking structural detail (Fig. 3). Three other males developed aberrant songs (Fig. 5). Excepting these three aberrant songs, the song patterns of the males were similar to, though not close copies of, the tutor songs. The songs of all males remained consistent through two photoperiodically induced breeding ‘seasons’ (November–January and April–May; Fig. 4). During these ‘season’, females were induced to sing by administration of testosterone. Six females sang during the first season, eight sang during the scond season, with five singing in both seasons. Unlike those of the males, the song patterns of all females (with the exception of F9), were not similar to the tutor models. The songs of those five females that sang during both seasons remained consistent through both seasons (Fig. 6). We conclude that because the sensitive phase for song learning generally coincides with natal philopatry, White-crowned Sparrows are predisposed to learn their natal dialect which they retain through life. This result may be an important factor in the maintenance of populations structured by geographic systems of dialects.

Song structure without auditory feedback: emendations of the auditory template hypothesis

Motor patterns of songs of swamp and song sparrows, Melospiza georgiana and M. melodia, deafened early in life display a significant degree of species-specific structure. Normal songs of the two species differ in the degree to which they are segmented. Swamp sparrow song consists of a single segment, and song sparrow songs are multisegmental. Song and swamp sparrows were deafened at 17 to 23 days, prior to the onset of song or subsong. The song sparrows developed more segments in their singing than the swamp sparrows. Species-specific trends were also evident in song durations and frequency characteristics. Abnormalities were found, however, in the morphology of the notes and syllables from which songs of early deafened sparrows are constructed. These results require emendation of the auditory template hypothesis of song learning in birds.

Song learning in the zebra finch ( taeniopygia guttata): Selectivity in the choice of a tutor and accuracy of song copies

The aim of the study was to look for possible selectivity of song learning in the zebra finch ( Taeniopygia guttata). Young males were provided with the opportunity to listen to two song tutors: their father and another male. Males raised under these conditions developed a song which way very similar to the song of their father. Within limits, such selectivity in the choice of a song tutor proved to be independent of the relative frequency of song output by the father or the neighbour, respectively. Although the general pattern of the father's song was adopted by their sons, the song copies were not identical in all details. Such ‘incorrect copying’ leads to the development of individual differences between males.

Levels of Organization in the Song of the Bobolink (Icteridae: Dolichonyginae)

Abstract and SummaryBy comparison with other icterids, the bobolink (Dolichonyx oryzivorus) sings an unusually long and complex song. The songs of four male bobolinks were analysed in terms of units at four different levels of analysis: the figure, the figure‐sequence, the song‐pattern, and the song. The different levels of analysis show different degrees of stereotypy and variation. Individual males in the study area differed in the frequency of use of the different song‐patterns and in the way they assembled them into songs. Immediate repetition of song patterns within a song was unusual. Songs sung from fixed perches were shorter than songs sung in flight. The results suggest that the length of bobolink song is in part a consequence of its use of the song as a part of an elaborate flight display, and that the unit we called the “song‐pattern” was closest to the unit designated “song” in most other species.

Song recognition and song pattern in a shorthorned grasshopper

1. Computer generated, artificial songs (Fig. 1) were played to grasshoppers of the gomphocerine speciesOmocestus viridulus L. in a temperature-regulated, echo-reduced chamber (Fig. 2). The animals often responded by singing their response song, and the occurrence of response songs was used to indicate the animals' preference for the artificial songs. At various temperatures, the chirp duration and impulse rate preferred by the animals were determined and compared with the magnitudes of these parameters in the response songs. 2. The duration of the response songs decreases with temperature (Fig. 5), and so does the chirp duration (Fig. 3). The chirp rate (which in this species is the reciprocal of the chirp duration) decreases during a response song (Fig. 6). 3. In the first experiments the chirp duration was varied in the artificial songs, while the ratio chirp rate to impulse rate was kept constant (as in the natural songs). The preferred chirp duration changes more with temperature than does the chirp duration of the response songs (Fig. 3). At all temperatures, songs with chirp durations half or double of the preferred one could also release a response song. The animals even responded to chirp durations outside the natural range (Fig. 3). 4. In the second experiments, the chirp rate (C) and impulse rate (I) at 28 °C (C28 and I28) and 38 °C were combined into four different songs: C28I28, C38I38, C28I38 and C38I28. The former two songs correspond to the natural songs at 28 ° and 38 °C, whereas the latter ones are artificial. The temperature of the listening animals was also varied. The choices made by femal grasshoppers showed that the chirp rate is the major parameter and the impulse rate the minor parameter in determining the acceptance of a song. 5. Four different criteria for measuring the female song discrimination were compared: (a) the behavioural threshold (i.e. the sound level of an artificial song which is just sufficient for response songs to be released in the females), (b) response or no response, (c) the number of response songs in a response, and (d) whether the response was given to the 1st, 2nd or 3rd song presentation. (a) was more sensitive than (b), and both gave rather similar results. In (c) and (d) the responses appeared to be independent of the type of songs presented. 6. The behavioural threshold increased before and decreased after egg deposition (Fig. 7).

Singing Behavior of the Five-Striped Sparrow

We studied the singing behavior and analyzed spectrographically the songs and calls of the Five-striped Sparrow (Aimophila quinquestriata). Its song consists of an introductory note followed by one to six, usually two, note complexes (a group of notes consistently occurring together). The same note complex is usually not repeated more than three times; nor are three different note complexes sung successively within the same song. Note complexes within songs are delivered in a non-random fashion, but the types of note complexes following other note complexes vary among individuals. Repertoires of three birds consisted of 159, 220, and 237 different songs and 43, 38, and 55 different note complexes, respectively. From 11,845 total songs recorded from all males, 99 different note complexes were recognized. Most note complexes were shared but several were unique to each individual. Five-striped Sparrows sing their song types many times before introducing others. Consequently, samples of songs as large as 1,000, 1,500, and 3,000 songs are necessary to obtain 90% of a bird's repertoire of note complexes. Complexity and versatility of song performances were greater when eggs or young were in the nest than when no nest or just the nest was present. In addition, Total Versatility values differed significantly when eggs were present and when eggs were absent. The number of different songs and different note complexes sung by each male also appeared to be related to the stage of nesting. The specific distinctiveness of a bird's singing performance is based partly on the number of different songs in the repertoire and the manner in which the songs are delivered (Kroodsma 1975). The singing performance of the Chipping Sparrow (Spizella passerina) represents a simple form of singing behavior in that one song type is sung repeatedly with little or no variation (Borror 1959). In contrast, the singing performance of the Brown Thrasher (Toxostoma rufum) is considered more complex because many different song types are sung before any are repeated (Borror 1964). Many avian singers, however, lie between these two extremes; they repeat many times a given song type, from a repertoire of several songs, before singing a different song type. Kroodsma (1975) has described an intermediate singing behavior in the Rock Wren (Salpinctes obsoletus), which he considered unique to this species. In a series of songs, few song types from a large repertoire are employed, and they are not often repeated successively. Another factor affecting the quality of a singing performance is the internal complexity of a song, i.e., the numbers of different components (notes) and their organization within the song. For example, the Indigo Bunting (Passerina cyanea) sings one particular song type throughout the day (Thompson 1968), as does the Chipping Sparrow, but this former song is comprised of several different notes varying in pitch and length-in contrast to the Chipping Sparrow's song, which is a series of identical notes. An individual, or a species of bird, then, can exhibit a singing behavior characte ized by various-sized song repertoires consisting of simple or complex songs sung in an unva ying or complicated manner (Borror 1961). A preliminary examination of the singing behavior of the Five-striped Sparrow (Aimophila quinquestriata) indicates that it can be classified with the Rock Wren's unique, interm diate behavior, yet the within-song components are few in number and uncomplicat d. Th songs of the Five-striped Sparrow have been briefly discussed in the literature (Borror 1971, Wolf 1977, Groschupf and Mills 1978), but no detailed spectrographic analysis ha been performed. We describe here the vocalizations and song patterning of nine Five-striped Sparrows recorded in southern Arizona and northern Mexico. Our study provides ubstantial information on the singing characteristics of a single species, which may be applied towards future studies of avian singing behavior.

Song Pattern Variation in the Sage Sparrow (Amphispiza belli): Dialects or Epiphenomena?

Abstract I investigated variation in the songs of Sage Sparrows (Amphispiza belli) breeding in the northwestern Great Basin over a 3-yr period. Individuals sang a single song type, which did not change during the day, through the breeding season, or between years. Although different individuals and populations differed in song parameters such as duration, delivery rate, and notes and note types per song, these variations exhibited no overall patterns with respect to geography or habitat. Similarity matrices based upon the sequential arrangement of note types in songs were used to draw comparisons within and between populations. Within-population vocal similarity of individuals varied considerably, from populations in which most neighboring individuals sang similar or identical songs to situations in which most individuals sang quite different songs; in one population, song variation was arrayed in "neighborhoods" of 3-5 individuals sharing similar songs, which differed markedly from those of adjacent clusters of individuals. Song variation between populations was significantly greater than that within populations. Some populations located close to one another shared many song elements and patterns, but other nearby populations were totally different and showed greater similarity with populations located some distance away. The degree of song similarity between populations was neither a simple function of the physical distance between the populations, nor was it related to the distribution of topographic barriers in this region. Populations with greater between-individual dissimilarity in song patterns were also more variable from one year to the next and occurred in habitats of lower vegetation stature and greater patchiness. Generally, however, the patterns of vocal variation within and between populations were unrelated to features of habitat structure, to the densities of Sage Sparrows or of other coexisting species, or to avian community attributes. I suggest that Sage Sparrows may have a simple, single-song repertoire because the song serves simple functions, and selection favoring a more elaborate song may be absent. The variety of patterns of within- and between-population vocal similarity may be associated with differences in population turnover rates, song ontogeny, dominance relationships, and dispersal, all of which require documentation to establish the foundations of vocal variation in this system (and others). The variety of population patterns, however, argues against a simplistic categorization of this species as dialectal or nondialectal. Much of the variation that is expressed may be a consequence of chance events and represents "epiphenomena" that are random with respect to natural selection.

Geographic Similarity and Year-To-Year Retention of Song in the Clay-Colored Sparrow (Spizella Pallida)

AbstractThe existence of dialects, individual variation in song within a population, and song retention from one year to the next were studied in populations of clay-colored sparrows in Manitoba and Ontario. Dialects were not found to exist in populations 12 km or 300 km apart in Manitoba. This was not because all songs were similar between the various areas, but because there were large variations among individuals within the different populations. An isolated population 2000 km distant in Ontario had only one characteristic different from the Manitoban populations; this difference is interpreted as arising from founding effects. Some factors which aid the development of dialects exist; males retained song types from one year to the next, and they showed a high rate of return between years on the study areas. However, in spite of potential isolating mechanisms (geographic separation and habitat differences), dialects did not develop, and it is argued that this results from an absence of song copying and cultural transmission of song pattern, and a lack of return of young to their natal area.

Variation in the Songs of Vesper Sparrows Pooecetes gramineus

Songs of 25 male vesper sparrows from seven locations were recorded and analyzed in the spring of 1976. The typical song consisted of a series of different syllable types, most of which were not shared with other individuals. Individuals at different locations shared as many syllable types as did individuals within locations; that is, vesper sparrows did not exhibit song dialects. This absence of dialects may be the result of two factors: (1) high rates of dispersal associated with the disruption of breeding areas, and (2) males learn portions or perhaps all of their songs (syllables) prior to autumn migration. INTRODUCTION Singing is a conspicuous part of the behavior of many birds during the breeding season and is generally associated with the occupation and defense of territories. In some species individuals from the same locality share similar songs and these songs are not shared with individuals from other localities. In such cases, the birds are said to have dialects. Such dialects exist in several species, among them the chaffinch Fringilla coelebs (Marler, 1952), white-crowned sparrow Zonotrichia leucophrys (Marler and Tamura, 1962), cardinal Cardinalis cardinalis (Lemon, 1966), Pyrrhuloxia Cardinalis sinuata (Lemon and Herzog, 1969), song sparrow Melospiza melodia (Harris and Lemon, 1972) and dark-eyed junco Junco hyemalis (Williams and MacRoberts, 1977). The vesper sparrow Pooecetes gramineus is an abundant breeding bird throughout much of its range, and its songs have been described by Borror (1961) and Kroodsma (1972). These studies have revealed variation in the song repertoires of individuals and populations, yet only Kroodsma performed a detailed sonographic analysis, and this involved only birds recorded in Oregon. Further, Kroodsma found dialects in Oregon vesper sparrows, whereas Borror reported none in the eastern United States. The present study provides a sonographic analysis of the songs of vesper sparrows recorded in Minnesota, and also seeks to determine whether this species possesses noticeable dialects. METHODS AND MATERIALS The songs of 25 male vesper sparrows were recorded from seven locations in southern Minnesota between 1 June and 24 July 1976. Because birds were not individually marked, care was taken to record each bird in only one singing bout. Recordings were made with a Nagra IV tape recorder with an Electrovoice 643A microphone mounted in a 48-cm parabolic reflector. Tape speed was 18 cm/ sec. Songs were analyzed on a Kay Electric Company Sonagraph (Model 6061B) set at high shape and wide band settings. A catalog of tracings produced from 372 sonagrams was used to distinguish syllable types, and each type was assigned a number. Syllables were matched against those in the catalog and a list of syllables was compiled for each song. Lists were examined to determine existence and distribution of recurring syllables (or sequences of syllables). Comparisons were then made to determine intraand interpopulation differences and similarities in syllable and song pattern repertoires. Intraand interpopulation analyses were made in the manner of Harris and Lemon (1972). For example, two syllables were common to the repertoires of birds MS1 (foursyllable total repertoire) and MS4 (nine-syllable total repertoire). This yields a

Three different diel rhythms of the calling song in the cricket, Gryllus campestris, and their control mechanisms*

ABSTRACT. Males of the cricket, Gryllus campestris L. (Orthoptera: Gryllidae), displayed three different diel patterns in the timing of their calling song: 55% of all males investigated were dark‐active, 25% light‐active and 20% light‐and‐dark‐active. Dark‐active males continued to stridulate in both constant darkness (DD) and constant light (LL) during the subjective night, with a circadian period usually shorter (in DD) or longer (in LL) than 24h. Light‐active males were mainly silent in DD but showed a circadian rhythm in LL, though with a 180° phase shift, i.e. activity during subjective night. This suggests that daytime activity has developed from nocturnal activity by a mechanism which prevents stridulation during darkness, and that both patterns are driven by the same endogenous clock. In the light‐and‐dark‐active males some stridulation takes place during darkness, so dark inhibition is not complete. Such incomplete inhibition seemed to occur only in highly active animals. The three diel distribution patterns of the calling song are discussed in relation to sharing the chances of attracting females.

The Songs and Singing Behavior of the Red-Eyed Vireo

-An audiospectrographic study of some 12,500 songs of Redeyed Vireos (Vireo olivaceus), from over 46 birds from nine states, provided data on song structure, vocal repertoires, and the birds' use of their repertoires. These songs have one or more syllables, each syllable consisting of one or more abrupt musical slurs. Each has a sizeable repertoire of syllable types, each of which may be used alone and/or with one or more other syllables to produce a number of different song types. The song type repertoires of individual birds ranged from 12 to 117 (average, 39.4). There is relatively little sharing of songs and syllable types among individuals and that which occurs is not always in proportion to the proximity of the birds concerned. A sings its different song types in a varied sequence, and rarely sings the same song type twice in succession; some types in the repertoire are sung frequently, while others are sung only rarely. No correlation was found between the song types sung, or their sequence, and the observable circumstances under which the songs were sung. Some geographic variation was found in the birds studied, but the significance of this variation is open to question. A Red-eyed Vireo in an early stage of song development has a very large repertoire of syllable types and uses them in many different combinations; as primary song is developed, some syllables and syllable combinations are perfected and others are discarded. It is probably largely a matter of chance what particular syllable and song types remain in the primary repertoire, but birds may tend not to duplicate the song and syllable types of their neighbors. The Red-eyed Vireo (Vireo olivaceus) is one of a number of passerines in which each individual has a repertoire of several to many different songs (song types, song patterns, themes, etc.), which it sings in a varied sequence, rarely, if ever, singing the same one twice in succession. Such singing was described as immediate variety by Hartshorne (1956, 1958, 1973), and may be represented ABCDEFG .... This sort of singing occurs, for example, in some other vireos (Borror 1972), the Wood Thrush (Hylocichla mustelina; Borror and Reese 1956, Borror 1964), and the Long-billed Marsh Wren (Cistothorus palustris; Verner 1975). My purpose here is to examine the songs and singing behavior of Red-eyed Vireos, and to determine the general features of the songs and the way they are sung. Lemon (1971) made a somewhat similar study, but he was concerned chiefly with the character of the songs and syllables, based on about 500 songs from only two birds; my study is based on considerably more material and it covers some aspects of Red-eyed Vireo singing not treated by Lemon. METHODS I studied 53 recordings (containing 12,509 songs), all made by me and in the tape collection of the Borror Laboratory of Bioacoustics, Department of Zoology, Ohio State University. I tape-recorded the songs at 15 inches per second, using a 24-inch parabola; most were made with a Nagra III recorder, but those made before 1960 (birds 30-49) were made with a Magnemite recorder. Forty-seven of the recordings (11,403 songs) represent 45 birds; it is uncertain how many birds are represented by the other five recordings. I numbered the birds individually and designated the five recordings representing an uncertain number of birds as bird 115. The birds studied included 2 from Maine, 5 from New Hampshire, 29 (+2 or more) from Ohio, 4 from North Dakota, and 1 each from Montana, Minnesota, Oklahoma, Texas, and Florida. Individuals are referred to in this paper by number; data on each are given in Table 1. Nearly all (about 94%) of the songs studied were graphed (with a Kay Sona-Graph, Model 7029A), as the songs were seldom positively identifiable by ear, even when the recording was played at a reduced tape speed. Song duration was measured to the nearest 0.01 s, and the maximum and minimum pitch was measured to the nearest 0.1 kHz; the time scale was based on the time of the Sona-Graph drum revolution and its circumference, and frequencies were based on a frequency scale put on the graph (by the Sona-Graph) with the songs. Measurements of songs not graphed were recorded as the average of those of other songs of the

Acoustic competition in bush crickets

Abstract. The bush crickets Platycleis albopunctata (Goeze) and Metriop‐tera roeselii (Hagenbach) interact acoustically in the laboratory. The interaction is principally one‐way, resulting in modification of the song pattern of P. albopunctata or its inhibition. Similarity of the frequency spectra of songs of both species is one of the principal reasons for reactivity. Nymphal male P. albopunctata individuals are randomly distributed in dense Brachypodium pinnatum L. grasslands. Adult males become regularly spaced with the onset of singing activity. Acoustic behaviour is the most likely mechanism maintaining regular spacing within the male P.albopunctata population. In many localities juvenile P. albopunctata and M. roeselii are sympatric, occurring together in the same vegetation. With the onset of singing activity by the adult males the two species separate though there is no detectable difference in habitat preference. The separation is effected by a negative phonotactic response by P. albopunctata to the song of M. roeselii. It is suggested that this response is derived from behaviour patterns that result in ‘territorial’ spacing within the P. albopunctata (male) population. This behaviour prevents the occurrence of song modification in the field but also excludes P. albopunctata from areas of suitable habitat where the population density of M. roeselii is high.

Influence of vibration on cricket hearing: Interaction of low frequency vibration and acoustic stimuli in the omega neuron

1. Low frequency substrate vibration affects the activity of the omega neuron (Wohlers and Huber 1978) in the cricket prothoracic ganglion (also called the large segmental auditory neuron; Popov et al. 1978). The details of this interaction have been studied inGryllus bimaculatus with extra- and intracellular recordings. 2. The threshold for excitation of the auditory omega interneuron by vibration is very high: 500 cm/ s2 acceleration (in the frequency range 100–800 Hz) or 300cm/s2 (1,000–2,000 Hz). This high threshold results in part from an active inhibitory process. 3. At accelerations of 3 cm/s2 or greater, vibrations in the range 100–2,000 Hz applied to the ipsilateral foreleg together with acoustic stimuli inhibit the response of the omega neuron to the acoustic stimulus. Vibration of the middle leg does not elicit this inhibition. 4. At a given acceleration the inhibitory effect of the various vibration frequencies tested is the mirror image of the threshold curve of the vibratory multi-unit response in the leg nerve as measured by Dambach (1972). This indicates that several vibration sensors in the foreleg (campaniform sensilla and subgenual organ) send inputs to the inhibitory circuit. 5. The amplitude of inhibition, expressed as the amount by which the response of the neuron to a 4.5-kHz, 70-dB sound pulse 70 ms long is reduced, is 10% for 3 cm/s2 at 400 Hz and averages 60% for 100 cm/s2 at 400 Hz. If vibratory and acoustic stimulus pulses 16 ms long are presented simultaneously, a 40% reduction in the response to a 60-dB sound is achieved with a vibration of only 25 cm/s2 at 400 Hz. 6. The peak of the inhibitory effect occurs 15–20 ms after the onset of vibration. The inhibition phase ends 40 ms after onset of the vibration pulse. 7. The NF neuron (Rheinlander et al. 1976) in the circumesophageal connective ofG. bimaculatus is also inhibited in its response to sound by vibration applied to the ipsilateral foreleg. 8. When synchronous acoustic and vibratory stimuli are presented in the temporal pattern of the conspecific song, the inhibitory circuitry can bring about an emphasis of the end of the syllable and of the pause in the song. A way in which this effect might occur even when the stimulus is entirely acoustic is discussed.

Response of the cercus-to-giant interneuron system in crickets to species-specific song

In addition to their high frequency stridulatory sound, crickets (Gryllus campestris) also produce low frequency airborne vibrations resulting from the strokes of the crickets' wings closing and opening during stridulation. Giant interneurons of the ventral cord, which receive inputs from cereal hairs, respond to these low frequencly components of cricket song up to a distance of some ten cm. The discharges are correlated to the time course of the acoustic stimulation, therefore allowing the transmission of the time patterns (syllables, chirps) of calling song, rivalry song and even courtship song. With simultaneous recording from both sides of the abdominal nerve cord, synchronous or alternating discharges can be detected, correlated either with syllables or intervals. The response mode depends on the position of the two individuals in relation to each other. Recording directly from singing males demonstrates interneuron response to selfgenerated signals, too. A possible communicative function of the system is discussed.

Local Song Traditions in Indigo Buntings: Cultural Transmission of Behavior Patterns Across Generations

Songs of indigo buntings were recorded at the E. S. George Reserve in southeastern Michigan from 1963 to 1980. A computer program was developed for the recognition of similar song patterns, using a catalog of audiospectrogram song figures and the sequence of the song figures. Neighboring buntings often matched their songs, usually with no more than five birds having the same song. Buntings from remote populations rarely matched the song of the George Reserve buntings. The probability of survival of song traditions was estimated from the historical data on the local songs. Most bunting songs of the 1960's no longer occur locally and either have disappeared or have altered beyond recognition by cultural drift. A few song types nevertheless have persisted in the local population for 15 years. Song types of adult buntings had an estimated annual exponential decay rate of 0.18 and an exponential half-life of 3.8 years. Estimated survival rates of songs were higher when more liberal criteria were used to recognize cases of matching songs, indicating that certain song traditions have changed through the accumulation of learning errors in cultural evolution. Survival of marked individual adult buntings was only a third of the survival of their song types. Survival of songs was similar whether estimated forward in time from the early samples or backward from the last samples. The equivalence is consistent with a random neutral substitution model of cultural evolution rather than with a competitive model that resembles an intense natural selection leading to many descendants being derived from a few founders. The local songs of adult indigo buntings are relatively long-lived behavior traditions that persist by social song learning outside of any family kinship line across several generations.

Auditory neurones in the brain of the cricketGryllus bimaculatus (De Geer)

1. Auditory neurones in the brain (supraoesophageal ganglion) of the cricketGryllus bimaculatus (De Geer) were intracellularly recorded and stained with Cobalt or Lucifer. 2. The cell bodies and arborisations of all recorded neurones are contained entirely within the supraoesophageal ganglion. Further, the cells all have arborisations which overlap extensively in the ventral-anterior protocerebrum, but there is no direct contact with the mushroom bodies. 3. The auditory neurones described fall into three morphological types. A. The first morphological type — theUnisegmentalauditorybrainneurone (UABN) — is restricted entirely to the protocerebrum and has no identifiable axon or terminal arborisations. Its Best Frequency (BF) is 16 kHz, near the conspecific courtship song frequency, and it is inhibited by low frequency sounds at high intensities. The intensity-response curve at 16 kHz has a greater dynamic range than those at higher or lower frequencies. B. The second morphological type — thePlurisegmentalauditorybrainneurone 1 (PABN1) — runs ventro-dorsally from proto- to deutocerebrum. The PABN1 has a bimodal tuning curve with a BF at 16 kHz and a secondary peak at 10 kHz. The intensity-response curve showing the greatest dynamic range occurs at 16 kHz. C. The third morphological type — thePlurisegmentalauditorybrainneurone 2 (PABN2) — sends branches from proto- to deutocerebrum, collaterals to its protocerebral and deutocerebral arborisations, and branches into the contralateral half of the brain. The PABN2 has a broader tuning curve than the other cells but is still most sensitive around 16 kHz. 4. All the cells exhibit spiking responses to sound, with tonic or phasic/tonic bursts which may exceed the duration of shorter stimulus tones. Sensitivities of the brain cells at their BF's are similar to those of receptors and ascending interneurones in this species. 5. All the brain cells recorded here can follow the pulse pattern of a synthetic calling song, adapting throughout a chirp, but only when chirps are presented at the BF. The initial response pattern is maintained over successive chirp presentations. This frequency-dependent encoding of the temporal properties of a stimulus is independent of sound intensity and, therefore, of auditory threshold. The underlying mechanism is probably different for each cell type. 6. The brain neurones have response properties and areas of arborisation which are similar to those of a previously identified ascending auditory interneurone. This ascending interneurone is thought to play a role in encoding the conspecific courtship song, with which these brain neurones may also be involved. The ventral-anterior protocerebrum may therefore represent a localised high-frequency auditory neuropile.

Unilateral nervous control of the syrinx in java sparrows (Padda oryzivora)

The syrinx of song birds contains two sound sources, the internal tympaniform membranes located one in each bronchus, that are controlled by the syringeal musculature. These muscles are innervated by the cervicalis descendens superior (CDS) branch of the hypoglossal nerve. Unilateral sections of the left CDS nerve in Java sparrows markedly disrupted tonal quality of the songs, although temporal parameters were unaltered. Bilateral CDS nerve sections caused greater disruption in frequency characteristics and temporal parameters were altered. Most birds died due to asphyxia soon after the operation. Right CDS nerve sections had much less effect, except on long whistles where extra low frequency sounds appeared, probably from the denervated right bronchus. Intact song pattern was restored within four months without re-innervation of the right syringeal musculature. This unilateral dominance in the control of the syrinx agrees with previous work and adds to the support for the “two voice” theory of sound production in birds (Greenewalt, 1968; Stein, 1968).