Ron Weisman

Absolute and Relative Pitch Production in the Song of the Black-Capped Chickadee

Black-capped Chickadee (Parus atricapillus) song consists of two notes, termed fee and bee. Frequency measures at three key points (at the start and end of fee, and at the start of bee) were obtained from the songs of a large sample of chickadees (n = 151) in the wild. In this sample, 19 birds produced songs shifted downward in frequency as well as their normal songs. Analysis of normal song revealed that fee declines in frequency in a glissando of nearly pure tone, then continues at greatly reduced amplitude at the start of bee; whereas bee, also a nearly pure tone, is always lower in frequency than either the start or end offee. The absolute pitches (frequencies) of these measures vary substantially among birds, but much less within individuals. In contrast, pitch intervals (ratios of higher to lower frequencies) for frequency changes among the three measures are highly invariant among birds. Moreover, chickadees with normal and frequency-shifted songs maintain virtually the same pitch intervals in both. This analysis suggests that the absolute and relative pitch constancies in chickadee song production may provide information for individual and species recognition, respectively.

Absolute and relative pitch processing in black-capped chickadees, Parus atricapillus

Abstract Playback studies have often identified note order as a feature in the recognition of conspecific song by passerines. Pitch change between successive notes in song could be an important source of order features. In two experiments, we varied the absolute and relative pitch in conspecific fee bee songs played to captive male black-capped chickadees. In experiment 1, songs beginning appreciably higher or lower in absolute pitch than normal song elicited less social response. In experiment 2, songs played at altered pitch intervals tended to elicit less combined agonistic and territorial response. These experiments indicate that chickadees are sensitive to both absolute and relative pitch information present in conspecific song.

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.

A motor-driven feeder for operant training in song birds

Conventional pigeon feeders can make noise, spill food, and injure birds in applications using small song birds as subjects. We developed a motor-driven feeder based on the principle of the piston to address these concerns.

Relative pitch recognition in white-throated sparrows, Zonotrichia albicollis

Abstract White-throated sparrows maintain a species-specific constant pitch interval (ratio of the higher to the lower frequency) during the pitch change between the first note (phrase 1) and the remaining notes (phrase 2) of ascending song. The interval may be an important source of relative pitch information about pitch change and thus, species identity over the broad absolute pitch range of white-throated sparrow songs. This study assessed the contribution of pitch interval perception, while controlling the absolute pitch of the notes. Using one phrase from each of four birds (A, B, C and D), two songs (AB and CD) with normal pitch intervals were created, such that phrases B and C were at the same absolute pitch. These same phrases were used to construct a third song with a reduced interval (CB) and a fourth song with an increased interval (AD). In playback tests, songs with normal pitch intervals elicited significantly more approach and song responses than songs with either reduced or increased intervals. The results suggest that white-throated sparrows are sensitive to the relative pitch features in conspecific song, independent of the absolute pitches of the song phrases.

ABSOLUTE AND RELATIVE PITCH PRODUCTION IN THE SONG OF THE WHITE-THROATED SPARROW (ZONO TRICHIA ALBICOLLIS)

ABSTRACT The songs of white-throated sparrows consist of 5 notes of very pure tonal quality. In ascending song, the pitch increases substantially from Note 1 to Note 2; whereas, in descending song, pitch decreases substantially from Note 2 to Note 3. Variability in the absolute pitch of each note is considerable among birds, but much less within individuals. Analysis of the major pitch changes in these songs shows that the pitch interval (ratio of the higher to the lower frequency), a measure of relative pitch constancy, predicts the frequency of the higher note in the pitch change more precisely than does the difference between the frequencies of the two notes, a measure of absolute pitch constancy. We conclude that white-throated sparrows produce relative rather than absolute pitch constancy during the major frequency changes in their songs and suggest that pitch interval may be an important cue in species recognition.

How birds identify species information in song: A pattern recognition approach ☆

Abstract Pattern recognition theory (PRT) is a diverse array of models concerned with the recognition of spatial and temporal patterns by humans and machines. We have sought to use the theory to help us understand how passerines identify species information in conspecific song. In this paper, application of PRT provided (a) a tentative model for song recognition, (b) an improved methodology for song playback experiments, and (c) a theoretical analysis of the representation of the temporal structure of song. In each instance, PRT suggested better experiments and more detailed analyses than had been available previously.

PITCH PROCESSING STRATEGIES IN BIRDS: A COMPARISON OF LABORATORY AND FIELD STUDIES

Over 50 studies have investigated how birds recognise conspecific song using playback (reviewed by Becker 1982; Weisman and Ratcliffe 1987). Typically, these experiments have compared the responses of territorial males (of mostly north temperate species) to broadcast of natural and altered species’ songs. Song playback simulates the intrusion of a rival male and usually elicits aggressive behaviour from the subject. If the alteration of a particular song feature reduces this aggression, compared to the natural song, one may infer the feature is important in song recognition. That is, either the song lacks species-specificity, or is recognised but not considered very threatening (Weary in press).