Susan M. Farabaugh

Vocal plasticity in budgerigars (Melopsittacus undulatus): Evidence for social factors in the learning of contact calls.

Distance or contact calls of 6 unrelated adult male budgerigars (Melopsittacus undulatus) were recorded before and during 8 weeks of social contact. The 6 birds were housed in 2 separate groups of 3 each in adjoining cages. Birds in each cage could hear but not see the birds in the neighboring cage. At the beginning of the study, none of the birds shared any contact call types. The first appearance of 1 birds imitation of a cagemates contact call type occurred after 1 week. Call type repertoires continued to change; some call types dropped out of the repertoires, and others were modified over time. Birds in the same cage shared the same dominant call type 8 weeks later, and the dominant call types differed between the 2 cages. Thus, budgerigars can learn calls as adults, and call type convergence is achieved through mutual vocal imitation of social companions. In the absence of social but not aural contact, vocal imitation was greatly reduced.

Song Sharing in a Group-Living Songbird, the Australian Magpie, Gymnorhina Tibicen. Part Iii. Sex Specificity and Individual Specificity of Vocal Parts in Communal Chorus and Duet Songs

In this paper we continue our study of the role of song in the social behavior of a cooperatively living songbird, the Australian magpie, Gymnorhina tibicen (Cracticidae). In this species, all members of a cooperative group sing and fight together in defense of their territory. Communal chorus songs consist of loud carol syllables; each individual sings a particular vocal role. We sampled the song repertoires of 24 magpies in 12 territorial groups in Queensland, Australia, and of 12 magpies in 4 territorial groups in the Manawatu region of New Zealand. Our results include: 1. Description of duet and chorus song. Carol portions of song are usually preceded by an introductory warble segment. Carol syllables are diverse in physical structure. We grouped 204 distinct carol syllables into 11 general classes. 2. Between-sex differences in syllable repertoires. Some syllable classes were sex-specific, and a few were sung by magpies of both sexes. Female-specific syllables were more complex structurally than those of males. Females had significantly (p 0.5) in the average percentage of the repertoire shared between same-sex birds who were vs were not territorial neighbors at our Queensland study site. 4. Carol song repertoires. The number of duet song types in each groups repertoire varied widely from group to group. Females had significantly (p<0.05) larger song repertoires than their mates. 5. Carol development in young birds. A young magpie seemed to sing variants of the carol syllables of only one parent, perhaps the same-sex parent, and echoed the parents carol syllables during communal choruses. 6. Geographic variation in carol syllables. Carol syllables of individuals at our New Zealand study site were also sex-specific, and could be grouped into general classes. No syllables were the same as those recorded from the Australian study birds. 7. Song context. We compared the amount of time magpie groups spent warbling, warble-caroling, and not singing, during five commonly occurring types of contexts. Warbles were most frequent in nonaggressive intragroup contexts. Warble-carols were most frequent in aggressive intergroup contexts. We discuss the function of song in social cohesion, and group and individual recognition ; evolution of duet song; singing behavior of females; and mechanisms of vocal learning.

Vocal Development in Budgerigars (Melopsittacus Undulatus): Contact Calls

Budgerigars have a complex vocal repertoire, some of which develops through learning. The authors examined the course of vocal development in budgerigars from hatching to about 4 weeks postfledging (approximately 85 days old). Food-begging calls showed changes in duration, peak frequency, bandwidth, and frequency modulation with age. Within a week of fledging, each bird produced a contact call bearing a strong resemblance to a shortened version of its patterned food-begging call. By 4 weeks postfledging, budgerigar contact call repertoires often contained more than one call type, and there was clear evidence of sharing and imitation among the calls of parents, fledglings, and other social companions. Perceptual testing showed that whereas acoustic variation in the structure of developing calls decreased both within and between nestling birds, the discrimination of these calls was easier for adult birds as young birds matured. These results suggest parallels with certain aspects of language development in humans.

ANALYSIS OF WARBLE SONG OF THE BUDGERIGAR MELOPSITTACUS UNDULATUS

ABSTRACT In this study we present a preliminary analysis of the structure of the complex multisyllabic warble song of the budgerigar Melopsittacus undulatus, a small, flock-living parakeet. We recorded eight male budgerigars from three different social groups, and one female. Budgerigar warble songs consist in long sequences of syllables that are diverse in structure, ranging from simple clicks to multinote, frequency-modulated musical-sounding syllables. We identified 42 syllable classes. Males shared a significantly greater percentage of their warble syllable-class repertoire with males in the same social group than with males in different groups. One male budgerigar preferentially imitated the syllables and temporal pattern of the abnormal warble of his cagemate (a male bird that had been reared in acoustic and social isolation) rather than the normal warble of other male budgerigars in adjoining cages. We discuss vocal imitation of social companions as a process of vocal learning, the potential role o...

Effects of deafening on the calls and warble song of adult budgerigars (Melopsittacus undulatus).

Budgerigars are small Australian parrots that learn new vocalizations throughout adulthood. Earlier work has shown that an external acoustic model and auditory feedback are necessary for the development of normal contact calls in this species. Here, the role of auditory feedback in the maintenance of species-typical contact calls and warble song in adult budgerigars is documented. Deafened adult birds (five male, one female) vocalized less frequently and showed both suprasegmental and segmental changes in their contact calls and warble song. Contact calls of all adult-deafened budgerigars showed abnormalities in acoustic structure within days to a few weeks following surgery. Within 6 months of surgery, nearly all contact calls produced by deafened birds were strikingly abnormal, showing highly variable patterns of frequency modulation and duration. The warble song of deafened male budgerigars also differed significantly from that of normal budgerigars on several acoustic measures. These results show that auditory feedback is necessary for the maintenance of a normal, species-typical vocal repertoire in budgerigars.

HEARING AND VOCALIZATIONS OF WILD-CAUGHT AUSTRALIAN BUDGERIGARS (MELOPSITTACUS UNDULATUS)

This study examined the hearing and contact calls of wild-caught Australian budgerigars (Melopsittacus undulatus) and compared these data to hearing and vocalizations in the much more extensively studied domesticated budgerigar. The spectral energy in the contact calls of both wild-caught and domesticated budgerigars falls almost exclusively in the frequency of 2-4 kHz. Absolute and masked thresholds were similar in both groups of birds. Similar to the results found in domesticated birds, critical ratio functions for the wild-caught budgerigars decreased at frequencies of 1.0 kHz-2.86 kHz and then increased again dramatically at frequencies above 2.86 kHz.

Recognition of contact calls by the budgerigar (Melopsittacus undulatus)

Playback studies have been used to assess whether birds recognize the calls and songs of other birds. In this experiment, contact calls were recorded from three pairs of budgerigars. These calls were then used as stimuli in playback experiments. Calls were stored on a computer and played to the birds either randomly or in response to calling. The bird’s vocal responses to these stimuli were recorded and counted. Results indicate that the birds showed a preference for particular calls. Overall, the birds responded more frequently to their mate’s call than to the calls of other birds.

SONG SHARING IN A GROUP-LIVING SONGBIRD, THE AUSTRALIAN MAGPIE. PART II. VOCAL SHARING BETWEEN TERRITORIAL NEIGHBORS, WITHIN AND BETWEEN GEOGRAPHIC REGIONS, AND BETWEEN SEXES

In this study we investigate the role of song in the social behavior of a cooperatively living songbird, the Australian magpie, Gymnorhina ticbicen (Cracticidae). In this species, kin and nonkin cooperative territorial groups exist in the same population. We sampled the vocal repertoire of 23 magpies in six territorial groups and the nonterritorial flock. Groups were located on two farms 2-3 km apart. This paper is the second of a two part paper. In Part I, we described song, and song and syllable repertoires; and we compared song sharing within and among kin and nonkin groups. Our results in Part II include: 1. Local geographic patterns in repertoire sharing. We found the average percentage of the repertoire shared between all pairwise combinations of birds to be lowest for birds in different localities, intermediate for birds in the same locality who are not neighbors, and highest for birds who are group mates or neighbors (p 0.79, Mann-Whitney rank sum test) than by birds of the opposite sex, when all birds of known sex were considered. However, when we considered sharing by group mates or neighbors only, birds did share a significantly (p<0.008) larger percentage of their repertoire with birds of the same sex than with birds of the opposite sex. 3. Sources of vocal imitation. To determine the sources of imitation, we calculated the proportion of a focal birds repertoire that is shared with different social classes of birds. Birds share more syllables exclusively with group mates than with neighbors, and they share more complex syllables with group mates than with other birds (p<0.001, G test of association). From these data, we discuss the role of vocal imitation in song learning, the timing and social setting of vocal learning, and the territorial functions of song. We conclude that vocal sharing through imitation may function in social affiliation within the group and in territorial defense between groups.