Convergence of untutored song in group-reared zebra finches (Taeniopygia guttata).

Zebra finches develop abnormal song if they cannot interact with adult song tutors during the 1st few months after hatching. The authors investigated whether untutored juveniles would learn song from each other. The birds were isolated from adult males at 10 days of age and their songs recorded after Day 80. By the authors' measures of syllable sharing and the judgments of human listeners, the songs of untutored brothers were as similar to each other as those of birds reared together with a tutor. The songs of group untutored birds were, however, more variable, and they contained abnormal elements, as did the songs of birds reared apart from all other males. The fact that untutored brothers copied song from each other raises the possibility that juveniles might influence each other's song development, even when adult tutors are present. If this were the case, it would increase the range of social interactions that determine which songs juveniles learn. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social enhancement and interference of food finding in zebra finches (Taeniopygia guttata).

In Experiment 1, pairs of naive zebra finches were allowed to find food in a same (local enhancement) or a different (local interference) location and in the presence of the same (stimulus enhancement) or different (stimulus interference) stimulus situation. The local interference condition resulted in significantly more time taken to find food and more search errors compared with both local enhancement and control (visually isolated) conditions. The stimulus interference condition resulted in searches of the stimulus associated with the partner's food source on an extinction posttest. In Experiment 2 the foraging behavior of a naive conspecific disrupted the performance of its knowledgeable partner and had stimulus interference effects on the knowledgeable partner in an extinction posttest like those found in Experiment 1. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequency ratio discrimination by zebra finches (Taeniopygia guttata) and humans (Homo sapiens).

We present the first evidence that songbirds can categorize stimulus sequences (note pairs) by frequency ratio (relative pitch) in an operant discrimination. Zebra finches (Taeniopygia guttata) and humans (Homo sapiens) were trained in a discrimination among 27 synthesized note pairs (9 S+ and 18 S– note pairs) with an operant go-no-go food-reward procedure. In the consistent-ratio discrimination groups, S+ note pairs had a common frequency ratio (1.12). In the jumbled-ratio discrimination group, S+ note pairs varied in frequency ratio (1.00, 1.12, and 1.26). Zebra finches and humans discriminated at least 8 of 9 consistent-ratio S+s, zebra finches discriminated 4 jumbled-ratio S+s, and humans discriminated few or no jumbled-ratio S+s. In this experiment, both species appeared to categorize note pairs by a consistent frequency ratio, but only zebra finches memorized several note pairs individually by rote. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Early experience and plasticity of song in adult male zebra finches (Taeniopygia guttata).

Zebra finches (Taeniopygia guttata) learn song primarily at 35–65 days of age, but birds deprived of experience at that stage may modify their songs later. Experiments on 5 groups examined the effect of varying early social experience on the plasticity of adult song. Major changes of song in adulthood were rare, and new syllables were memorized only in the more socially impoverished groups. Most songs underwent minor changes, in syllable structure or stereotypy, as well as in the addition or deletion of syllables. Two factors appeared to be important in determining the amount of change: the extent of social deprivation that the bird had experienced and, in the case of group-reared birds, the degree of song matching between social companions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial unmasking of birdsong in zebra finches (Taeniopygia guttata) and budgerigars (Melopsittacus undulatus).

Budgerigars and zebra finches were tested, using operant conditioning techniques, on their ability to identify a zebra finch song in the presence of a background masker emitted from either the same or a different location as the signal. Identification thresholds were obtained for three masker types differing in their spectrotemporal characteristics (noise, modulated noise, and a song chorus). Both bird species exhibited similar amounts of spatial unmasking across the three masker types. The amount of unmasking was greater when the masker was played continuously compared to when the target and masker were presented simultaneously. These results suggest that spatial factors are important for birds in the identification of natural signals in noisy environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of humidity on reproductive behavior in male and female zebra finches (Taeniopygia guttata).

Zebra finches (Taeniopygia guttata) are regarded as opportunistic breeders with reproductive behaviors mediated by short-term proximal environmental conditions. This article provides experimental evidence for the role of humidity in reproductive behaviors. Zebra finches were subjected to experimentally manipulated high levels of relative humidity. Males gathered more nest material and sang more. Females showed no relationship between humidity and gathering nest materials, egg laying, or changes in rates of vocalization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Song-note discriminations in zebra finches (Taeniopygia guttata): Categories and pseudocategories.

Sturdy, Phillmore, and Weisman (1999) developed a simple, reliable procedure for classifying zebra finch (Taeniopygia guttata) song notes into types using exemplar notes from 4 captive North American laboratory colonies. In the present experiment, zebra finches learned true-category song-note discriminations based on Sturdy et al.'s note-type classification faster than pseudocategory discriminations based on random assortments of the same notes. Also, birds in the true-category discrimination were able to sort notes not heard during training into the same categories as the training notes. This evidence suggests that zebra finches accurately sort conspecific song notes into the same open-ended categories as Sturdy et al.'s human observers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination of auditory distance cues by black-capped chickadees (Poecile atricapillus) and zebra finches (Taeniopygia guttata).

The authors examined auditory distance perception using a go/no-go operant discrimination task in the laboratory. They taught male black-capped chickadees (Poecile atricapillus) and male zebra finches (Taeniopygia guttata) to discriminate degraded (far) from undegraded (near) versions of male chickadee songs and female zebra finch calls, showing for the 1st time that males can discriminate distance cues in heterospecific vocalizations and in female calls. Chickadees learned faster than zebra finches, and both species learned to discriminate chickadee songs faster than zebra finch calls. Chickadees more than zebra finches attended to amplitude in tests pitting it against other distance cues, demonstrating that amplitude is a potentially useful cue for estimating distance from vocalizations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development and adult phase plasticity of syllable repetitions in the birdsong of captive zebra finches (Taeniopygia guttata).

Oscines learn their birdsongs from tutors. The authors found that a small fraction (approximately 7%) of captive male zebra finches (Taeniopygia guttata) produce variant acoustic birdsong profiles consisting of repetitions of single song syllables at high frequencies. Juvenile offspring of nonrepeaters can selectively learn the syntactic rule or habit of repeating syllables from repeaters. Adult tutored syllable repeaters, unlike spontaneous repeaters, undergo a form of song plasticity involving progressive reduction of the mean number and variance of repeated syllables as a function of long-term exposure to nonrepeater songs without altering the number or sequence of syllables within motifs. These findings suggest that aspects of song syntax or temporal frame can be acquired independently of song syllable or spectral content, and plasticity involving restorative alteration of acquired variant temporal frames can occur after the closure of the critical period for song learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The disassociation of visual and acoustic conspecific cues decreases discrimination by female zebra finches (Taeniopygia guttata).

Female zebra finches (Taeniopygia guttata) use visual and acoustic traits for accurate recognition of male conspecifics. Evidence from video playbacks confirms that both sensory modalities are important for conspecific and species discrimination, but experimental evidence of the individual roles of these cue types affecting live conspecific recognition is limited. In a spatial paradigm to test discrimination, the authors used live male zebra finch stimuli of 2 color morphs, wild-type (conspecific) and white with a painted black beak (foreign), producing 1 of 2 vocalization types: songs and calls learned from zebra finch parents (conspecific) or cross-fostered songs and calls learned from Bengalese finch (Lonchura striata vars. domestica) foster parents (foreign). The authors found that female zebra finches consistently preferred males with conspecific visual and acoustic cues over males with foreign cues, but did not discriminate when the conspecific and foreign visual and acoustic cues were mismatched. These results indicate the importance of both visual and acoustic features for female zebra finches when discriminating between live conspecific males. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequency–range discriminations: Special and general abilities in zebra finches (Taeniopygia guttata) and humans (Homo sapiens).

The acoustic frequency ranges in birdsongs and human speech can provide important pitch cues for recognition. Zebra finches and humans were trained to sort contiguous frequencies into 3 or 8 ranges, based on associations between the ranges and reward. The 3-range task was conducted separately in 3 spectral regions. Zebra finches discriminated 3 ranges in the medium and high spectral regions faster than in the low region and discriminated 8 ranges with precision. Humans discriminated 3 ranges in all 3 spectral regions to the same modest standard and acquired only a crude discrimination of the lowest and highest of 8 ranges. The results indicate that songbirds have a special sensitivity to the pitches in conspecific songs and, relative to humans, have a remarkable general ability to sort pitches into ranges. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of changes in timbre and harmonicity in complex sounds by zebra finches (Taeniopygia guttata) and budgerigars (Melopsittacus undulatus).

Thresholds for detecting alterations in the timbre and harmonicity of complex harmonic signals were measured in zebra finches, budgerigars, and humans. The stimuli used in this experiment were designed to have particular salience for zebra finches by modeling them after natural zebra finch calls. All 3 species showed similar abilities for detecting an amplitude decrement in a single component of a harmonic complex. However, zebra finches and budgerigars were extraordinarily sensitive to the mistunings of single harmonics and exhibited significantly lower thresholds compared with humans at 2 different fundamental frequencies, 570 Hz and 285 Hz. Randomizing relative phases of components in a harmonic stimulus resulted in a significant increase in threshold for detecting in zebra finches but not in humans. Decreasing the duration of mistuned harmonic stimuli resulted in higher thresholds for both birds and humans. The overall superiority of birds in discriminating inharmonicity suggests that birds and mammals may use different strategies in processing these complex harmonic sounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequency-range discriminations and absolute pitch in black-capped chickadees (Poecile atricapillus), mountain chickadees (Poecile gambeli), and zebra finches (Taeniopygia guttata).

The acoustic frequency ranges in birdsongs provide important absolute pitch cues for the recognition of conspecifics. Black-capped chickadees (Poecile atricapillus), mountain chickadees (Poecile gambeli), and zebra finches (Taeniopygia guttata) were trained to sort tones contiguous in frequency into 8 ranges on the basis of associations between response to the tones in each range and reward. All 3 species acquired accurate frequency-range discriminations, but zebra finches acquired the discrimination in fewer trials and to a higher standard than black-capped or mountain chickadees, which did not differ appreciably in the discrimination. Chickadees' relatively poorer accuracy was traced to poorer discrimination of tones in the higher frequency ranges. During transfer tests, the discrimination generalized to novel tones when the training tones were included, but not when they were omitted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Absolute pitch: Frequency-range discriminations in pigeons (Columba livia)--comparisons with zebra finches (Taeniopygia guttata) and humans (Homo sapiens).

Absolute pitch (AP) is the ability to classify individual pitches without an external referent. The authors compared results from pigeons (Columba livia, a nonsongbird species) with results (R. Weisman, M. Njegovan, C. Sturdy, L. Phillmore, J. Coyle, & D. Mewhort, 1998) from zebra finches (Taeniopygia guttata, a songbird species) and humans (Homo sapiens) in AP tests that required classification of contiguous tones into 3 or 8 frequency ranges on the basis of correlations between the tones in each frequency range and reward. Pigeons' 3-range discriminations were similar in accuracy to those of zebra finches and humans. In the more challenging 8-range task, pigeons, like zebra finches, discriminated shifts from reward to nonreward from range to range across all 8 ranges, whereas humans discriminated only the 1st and last ranges. Taken together with previous research, the present experiments suggest that birds may have more accurate AP than mammals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination of video images by zebra finches (Taeniopygia guttata): Direct evidence from song performance.

Adult male zebra finches (Taeniopygia guttata) were found to work for the reward of viewing silent video images. In addition, birds that were exposed either passively or contingently upon key pecking to an array of moving images randomly displayed on a video monitor responded with song, depending on the content of the images. In both Experiment 1 (with full-screen images) and Experiment 2 (with sections of images), the subjects clearly discriminated between bird and nonbird pictures. Stimulus movement was found to affect the response only when bird pictures were presented, thus ruling out the evidence for species recognition. The methodology offers a new behavioral assay for investigating categorical perception of pictorial stimuli by songbirds. It has also the potential to provide further insights into the role of visual cues in song learning and social interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in aggressive behavior in zebra finches (Poephila guttata).

Aggressive behavior between pairs of female or male zebra finches (Poephila guttata) was measured before, during, and after presentation of either a female or male finch (the stimulus) in an adjacent cage. Presentation of the stimuli led to marked increases in aggressive behavior for both sexes of Ss, such that presentation of a female stimulus caused an elevation in aggression in male pairs and presentation of a male stimulus caused an elevation in female pairs. These results are interpreted in the context of competition for mates in species, such as zebra finches, that have long-term monogamous pair bonds and biparental care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Syllable chunking in zebra finch (Taeniopygia guttata) song.

Examined how 61 young zebra finch males copied song from 5 adult tutors. Zebra finch song consists of a string of 5–25 distinct syllables, and these syllables were copied as chunks, or strings of consecutive syllables (modal length?=?3). The silent interval between 2 syllables was copied as part of the syllable after the silence. Copied chunks had boundaries that fell at consistent locations within the tutor's song, marked by a relatively long intersyllable silent period, a transition between call-like and noncall-like syllables, and a tendency for the tutor male to stop his song short. Young males also tended to break their songs off at the bondaries of the chunks they had copied. Chunks appear to be an intermediate level of hierarchy in song organization and to have both perceptual (syllables were learned as part of a chunk) and motor (song delivery was broken almost exclusively at chunk boundaries) aspects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of temporal properties in self-generated songs by Bengalese finches (Lonchura striata var. domestica).

In the songbird forebrain, neuronal selectivity for temporal properties of each bird's self-generated song has been well described, but the behavioral and perceptual correlates of this selectivity are not known. By operant procedures, the authors trained Bengalese finches (Lonchura striata var. domestica) to discriminate between songs that were played normally and in reverse. Male Bengalese finches learned the discrimination quicker when their self-generated song was used as a stimulus than when a song of another conspecific bird was used. When the global note order was retained but each note was locally reversed, the song was more likely to be regarded as a forward song by the singer himself, but not by other birds. These results provide psychophysical evidence that the special processing of the self-generated song observed at the neural level might reflect an individual's perception of his self-produced song. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental determination of a unit of song production in the zebra finch (Taeniopygia guttata).

Zebra finch (Taeniopygia guttata) song is composed of syllables delivered in a set order. Little is known about the program that controls this temporal delivery. A decision to sing or not to sing may or may not affect the entire song. Song, once commenced, may continue or may halt. If song is halted, stops may occur only at certain points. Seven zebra finches were presented with short bursts of strobe light while engaged in song. The variables of interest were whether the birds stopped and where they stopped. The results can be summarized as follows: Ongoing zebra finch song can be interrupted, interruptions occur at discrete locations in song, and the locations almost always fall between song syllables. These results reveal a functional representation of song production and place constraints on possible neural mechanisms that underlie song production in zebra finches and probably other oscine species. The results also raise hypotheses about the elements of song perception and memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Timbre control in zebra finch (Taeniopygia guttata) song syllables.

Zebra finch (Taeniopygia guttata) song syllables often include harmonically related frequency components. These harmonics may be suppressed, and this differential emphasis varies between the syllables in a song and between individual birds' songs. These patterns of harmonic suppression are timbre. Individual syllables' patterns of harmonic suppression are constant within adult males' songs. Young males that imitate the songs of older males also imitate their patterns of harmonic suppression. Syringeal denervation distorts these patterns, which suggests that they are produced through active control of the vocal organ. The selective suppression and emphasis of some harmonics creates a great number of possible timbre variants for any one syllable. These add signal diversity to the limited array of frequency modulations and range of fundamental frequencies found in zebra finch song. Analyses of bird song that disregard timbre may overlook a feature that is important in vocal communication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)