Title from title page of PDF (University of Missouri--St. Louis, viewed February 10, 2010). Includes bibliographical references.

Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on Apr. 14, 2010). Includes bibliographical references (p. 28-34).

A three-part study of the vocal and visual cues important for species recognition in six species of Darwin's Finches (Geospiza) in the Galapagos is presented. Part I quantifies structure and species-specificity of advertising song. Part II describes experiments on song function and recognition. Part III examines the role of morphology in mate recognition and reproductive isolation. Geospiza song is variable and lacks species-specificity, due to intrapopulation song polymorphism, dialect divergence, song parallelism and interspecific song overlap. Song functions in conspecific territorial communication. Much intraspecific song variation apparently has little functional significance, although vocal confusion between syntopic G. fuliginosa and G. fortis may exist. Visual recognition involves morphological (non-plumage) stimuli of both head and body. Male recognition of potential mates functions in reproductive isolation, and character displacement in recognition ability occurs. Visual cues appear to override vocal ones in short-range communication. Lack's (1945) hypothesis that Geospiza use characters specialized for feeding as mate identification cues is confirmed. Low interspecific song divergence is probably related to the evolution of visual species recognition.

Chapter 1 provides an introduction to the thesis by discussing the relevant literature on vocal learning in songbirds and parrots, with particular reference to calls, and setting out the aims of the following chapters. Chapter 2 concerned an investigation of the similarity in the distance calls within and between families of zebra finches, involving fostering young birds to non-related parents. Male offspring were most similar in their distance calls to their male siblings with which they were raised and the adult male which raised them, suggesting an environmental influence in the acquisition of the call. There was also an indication that the call may be, at least in part, inherited. Females were most similar to their mothers and female siblings, though not to the same extent as in males. Chapter 3 examined whether male zebra finches could exhibit vocal plasticity in adulthood, by learning new calls from other conspecifics, and whether social deprivation during a young bird's development would accentuate this tendency. Adult zebra finches could not learn new calls from other similarly raised cagemates, even if these birds were reared under conditions of extreme social deprivation and were presented with an appropriate normally-raised adult male tutor. Chapter 4 described a study which investigated whether adult male budgerigars housed in soundproof boxes, could learn new calls from a tape recording in the absence of any social stimuli. Learning from tapes was very limited with only one bird producing an accurate copy of the playback, emphasising the importance of an interactive social context in vocal learning. Chapter 5 attempted to determine exactly which social factors were most influential in determining the extent of call matching between adult male budgerigars. Certain individuals did match more closely in their contact calls; close proximity appeared to promote call convergence between cagemates. Chapter 6 examined the effect of adding an unfamiliar budgerigar to an established flock, on the group specific call. It was found that, contrary to expectation, mutual imitation by all flock mates did not occur as other studies have shown, and that 'new recruits' conformed to the shared group call. Chapter 7 concluded the findings of the five experimental chapters, and discussed their significance with reference to previous studies, including ideas for further investigation.

The acoustic adaptation hypothesis was reviewed. This predicts that the sounds used by birds singing in a dense habitat should be of lower frequency than those in a more open habitat, and that sounds should be spaced out more in time in denser habitats to avoid degradation by reverberations. These predictions were tested by recording chaffinch (Fringilla coelebs) songs in open scrub, coniferous plantations, and a natural Scots pine forest, but the results obtained gave little support to the predictions made. Transmission of white noise and the songs of blue (F. teydea) arid Canary Islands chaffinches (F. c. tintillon) through laurel and Canarian pine forests on Tenerife revealed a sound window of less excess attenuation than expected in both habitats at frequencies of 2-3kHz. The song of the blue chaffinch appears to be better adapted for transmission through both habitats. Computer simulations of the formation of dialects by random copying of the songs possessed by neighbours predicted a strong effect of both the number of neighbours available to learn from, and the repertoire size, upon the songs' longevity and the number of birds sharing a particular song type. If the song type which was commonest amongst those sung by neighbours was learnt, larger groups of birds were found to share song types. At low copying error rates these groups approached the size of those described for the white-crowned sparrow (Zonotrichia leucophrys). A computer program which uses the dynamic programming algorithm to compare objectively shapes digitised from sonagrams was developed and tested with syllables from chaffinch songs.

This thesis examines the importance of visual, vocal and behavioural cues for song tutor choice in zebra finches, Taeniopygia guttata. Zebra finch males normally copy song at 35 to 65 days of age. In the wild the young become independent at about 35 days of age and form small flocks in the area of the colony where they will be exposed to a variety of song tutors. In Chapter 3 captive zebra finches are provided with the opportunity to learn from two conspecifics at 35 days of age. Female-raised males which are housed with two unrelated tutors prefer to learn from the one who is, most aggressive towards them. Normally-raised males which are housed with an unrelated tutor and one, whose song is similar to the father's tend to copy the tutor with the similar song: this relies on the young bird learning some characteristics of his father's song before independence. Chapter 4 shows that males and females can discriminate between their father's song and those of other males. Visual, vocal and behavioural cues are all important for species-specificity. Cross-fostering using Bengalese finches, Lonchura striata, as foster-parents is an important tool for studying this. Chapter 5 looks at Bengalese finch song development; Chapter 6 compares song development in cross-fostered zebra finches and Bengalese finches. Visual cues are important for tutor choice and young males of both species which are provided with a zebra finch singing Bengalese song and a Bengalese finch singing zebra finch song prefer the conspecific tutor (Chapter 7). Chapter 8 suggests that conspecific song elements are not important for zebra finches: there is no tendency to prefer a tutor with normal song over one singing Bengalese song. Cross-fostering can also, influence the timing of song learning. Males which are housed successively (Chapter 9) or simultaneously (Chapter 10) with both species tend to reproduce song which they heard before independence in addition to learning from the tutor which they heard after independence at 35 to 65 days of age: this indicates that the timing of the sensitive phase is flexible and mediated by both experience and age. There are a number of similarities between song learning and sexual imprinting which are discussed in Chapter 11. Crucial to these studies is a knowledge of the two species' behaviours. Chapter 12 compares, parental behaviour in captivity. Chapter 12 concludes with a plea for more research in the wild.

Bird song provides us with one of the best models with which to investigate learning, communication and the organisation of behavioural repertoires. This study describes temporal organisation and song pattern choice in the chaffinch in order to develop hypotheses for possible song control mechanisms. Influences of the song learning process and motivation on performance are tested in experiments. The role of nature and nurture in shaping females' song preferences is investigated by using operant tasks. A first quantitative assessment of temporal organisation within songs is provided in Chapter 2. Chaffinches sing with eventual variety, each song type in a male's repertoire is repeated a few times before a switch to the next type occurs. Chapter 3 tests two hypotheses for mechanisms controlling song type switching: that a maximum number of repetitions or that a maximum duration (time window) sets the upper limit. Clear evidence for a time window as an upper constraint was found in wild birds as song type bouts with many repetitions were sung at fast rates only, whereas those with few repetitions could be sung at either fast or slow rates. However, the mean number of song type repetitions depended strongly both on the subject and the song type. No evidence could be found that number of repetitions per song type were influenced by the tutor's singing style in hand-reared chaffinches (Chapter 4). Playbacks of single songs to wild males revealed the motivation dependent flexibility of the system as the birds reacted with distinct increases in bout duration (Chapter 5) but showed a different response to playbacks of songs that were the same or different from that being performed by the subject. Song was used as a positive reinforcer in an operant conditioning task with female chaffinches (Chapter 6). The influence of early exposure to song on later preferences and the relative importance of the trill and flourish sections of the song were tested this way. Females showed no preference for familiar over unfamiliar songs, but preferred songs with flourishes over those without.

No description available.

This thesis examines whether scramble competition is associated with social learning. The question is explored via a comparative study involving two species of grassfinches, Amadina fasciata, and Taenopygia guttata. These finches vary in the degree to which they employ scramble competition while foraging, but are otherwise similar behaviourally and morphologically. General problems associated with the application of the comparative method to the testing of learning specializations are discussed. Functional improvements to previously employed approaches are proposed, and then implemented in a novel methodology and statistical approach to analysing the data, the Manova approach. The results of the study suggest that there is no link between scramble competition and social learning in these two species. When the effects of confounding variables are removed from the interspecific comparison, the species do not appear to differ in their social learning abilities. The results also indirectly suggest that some forms of social learning occur through the mechanisms of general learning.

No description available.