Browsing by Author "Sturdy, Christopher B."

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    Absolute pitch in boreal chickadees and humans: exceptions that test a phylogenetic rule
    (2010) Weisman, Ronald G.; Balkwill, Laura-Lee; Hoeschele, Marisa; Moscicki, Michele; Bloomfield, Laurie L.; Sturdy, Christopher B.
    This research examined generality of the phylogenetic rule that birds discriminate frequency ranges more accurately than mammals. Human absolute pitch chroma possessors accurately tracked transitions between frequency ranges. Independent tests showed that they used note naming (pitch chroma) to remap the tones into ranges; neither possessors nor nonpossessors were accurate at octave (pitch height) naming. Boreal chickadees discriminated frequency ranges less accurately than other birds; they tracked reward across several lower frequency ranges but failed at frequencies over 4000 Hz. The results revealed the error of describing species differences solely in terms of their discrimination of frequency ranges. Exceptions to the rule disappear when the rule is restated in terms of underlying mechanism: birds are superior to mammals in the ability to use absolute pitch height perception to discriminate pitches and ranges of pitches.
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    Black-capped chickadees Poecile atricapillus sing at higher pitches with elevated anthropogenic noise, but not with decreasing canopy cover
    (2012) Proppe, Darren S.; Avey, Marc T.; Hoeschele, Marisa; Moscicki, Michele; Farrell, Tara M.; St Clair, Colleen Cassady; Sturdy, Christopher B.
    Several songbird species sing at higher frequencies (i.e. higher pitch) when anthropogenic noise levels are elevated. Such frequency shifting is thought to be an adaptation to prevent masking of bird song by anthropogenic noise. However, no study of this phenomenon has examined how vegetative differences between noisy and quiet sites influence frequency shifting. Variation in vegetative structure is important because the acoustic adaptation hypothesis predicts that birds in more open areas should also sing at higher frequencies. Thus, vegetative structure may partially explain the observation of higher frequency songs in areas with high levels of anthropogenic noise. To distinguish between frequency shifting due to noise or vegetative structure we recorded the songs of black-capped chickadees Poecile atricapillus vocalizing in high and low noise sites with open and closed canopy forests. Consistent with the noise-dependent frequency hypothesis, black-capped chickadees sang at higher frequencies in high noise sites than in low noise sites. In contrast, birds did not sing at higher frequencies in sites with more open canopies. These results suggest that frequency shifting in chickadees is more strongly related to ambient noise levels than to vegetative structure. A second frequency measure, inter-note ratio, was reduced at higher levels of canopy cover. We speculate that this may be due to a non-random distribution of dominant males. In sum, our results support the hypothesis that some birds sing at higher frequencies to avoid overlap with anthropogenic noise, but suggest that vegetative structure may play a role in the modification of other song traits.
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    Dominance signalled in an acoustic ornament
    (2010) Hoeschele, Marisa; Moscicki, Michele; Otter, Ken A.; van Oort, Harry; Fort, Kevin T.; Farrell, Tara M.; Lee, Homan; Robson, Scott W. J.; Sturdy, Christopher B.
    In many species, males use auditory signals to attract females and females select males based on their dominance status. Here we show that information on dominance status in male black-capped chickadees, Poecile atricapillus, a small, temperate, North American songbird, can be extracted from individual songs. We found that the relative amplitude of the two notes in the ‘fee bee’ song of this species was more consistent in dominant males. Furthermore, females responded differently to presentations of single song exemplars from males of different dominance status, with females vocalizing more and performing more motor behaviours during the presentation of dominant songs. Our study suggests that non-pitch-based cues within single vocalizations can both reliably indicate relative rank and be discriminated by females.
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    Identifying absolute pitch possessors without using a note-naming task
    (2012) Weisman, Ronald G.; Balkwill, Laura-Lee; Hoeschele, Marisa; Moscicki, Michele; Sturdy, Christopher B.
    English: Most researchers measure absolute pitch (AP) using note-naming tasks that presume expertise with the scales of Western music. If note naming constitutes the only measure, then by fiat, only trained musicians can possess AP. Here we report on an AP test that does not require a note-naming response. The participants were 15 AP possessors and 45 nonpossessors defined by note naming. We presented sine tones tuned to the 12-note chromatic scale in a go/no-go discrimination between the first and second 6 notes in 3 successive octaves. This half-octave discrimination test predicted AP performance in the note-naming test with high accuracy and, in particular never falsely predicted that a nonpossessor defined by note naming was an AP possessor. We found 2 heterogeneities in the AP performance of our participants. Incremental AP possessors scored above the criterion for AP in 2 note-naming tests but required 2 sessions to attain accurate half-octave discriminations. Variable AP/NAP (nonabsolute pitch) possessors scored above criterion for AP in 1 naming test and below criterion in a second naming test but below criterion on the half-octave test. Our findings suggest the use of the half-octave discrimination test in future research into heterogeneities in AP and, most important, in the search for AP possessors untutored in music.
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    Neural correlates of threat perception: neural equivalence of conspecific and heterospecific mobbing calls is learned
    (2011) Avey, Marc T.; Hoeschele, Marisa; Moscicki, Michele; Bloomfield, Laurie L.; Sturdy, Christopher B.
    Songbird auditory areas (i.e., CMM and NCM) are preferentially activated to playback of conspecific vocalizations relative to heterospecific and arbitrary noise [1-2]. Here, we asked if the neural response to auditory stimulation is not simply preferential for conspecific vocalizations but also for the information conveyed by the vocalization. Black-capped chickadees use their chick-a-dee mobbing call to recruit conspecifics and other avian species to mob perched predators [3]. Mobbing calls produced in response to smaller, higher-threat predators contain more ''D'' notes compared to those produced in response to larger, lower-threat predators and thus convey the degree of threat of predators [4]. We specifically asked whether the neural response varies with the degree of threat conveyed by the mobbing calls of chickadees and whether the neural response is the same for actual predator calls that correspond to the degree of threat of the chickadee mobbing calls. Our results demonstrate that, as degree of threat increases in conspecific chickadee mobbing calls, there is a corresponding increase in immediate early gene (IEG) expression in telencephalic auditory areas. We also demonstrate that as the degree of threat increases for the heterospecific predator, there is a corresponding increase in IEG expression in the auditory areas. Furthermore, there was no significant difference in the amount IEG expression between conspecific mobbing calls or heterospecific predator calls that were the same degree of threat. In a second experiment, using hand-reared chickadees without predator experience, we found more IEG expression in response to mobbing calls than corresponding predator calls, indicating that degree of threat is learned. Our results demonstrate that degree of threat corresponds to neural activity in the auditory areas and that threat can be conveyed by different species signals and that these signals must be learned.
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    Note types and coding in parid vocalizations: the chick-a-dee call of the boreal chickadee (Poecile hudsonicus)
    (2011) Moscicki, Michele; Hoeschele, Marisa; Bloomfield, Laurie L.; Modanu, Maria; Charrier, Isabelle; Sturdy, Christopher B.
    An important first step in characterizing a vocalization is to classify, describe, and measure the elements of that vocalization. Here, this methodology is employed to study the chick-a-dee call of the boreal chickadee (Poecile hudsonicus). The note types (A, B, C, D, and Dh) in a sample of boreal chickadee calls are identified and described, spectral and temporal features of each note type are analyzed, and production phenomena in each note type are identified and quantified. Acoustic variability is compared across note types and individuals to determine potential features used for note-type and individual discrimination. Frequency measures appear to be the most useful features for identifying note types and individuals, though total duration may also be useful. Call syntax reveals that boreal chick-a-dee calls follow a general rule of note-type order, namely A-B-C-Dh-D, and that any note type in this sequence may be repeated or omitted. This work provides a thorough description of the boreal chickadee chick-a-dee call and will serve as a foundation for future studies aimed at elucidating this call’s functional significance within this species, as well as for studies comparing chick-a-dee calls across Poecile species.
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    Note types and coding in parid vocalizations: the chick-a-dee call of the chestnut-backed chickadee (Poecile Rufuscens)
    (2009) Hoeschele, Marisa; Gammon, David E.; Moscicki, Michele; Sturdy, Christopher B.
    A first step to understanding how a species communicates acoustically is to identify, categorize, and quantify the acoustic parameters of the elements that make up their vocalizations. The "chick-a-dee" call notes of the chestnut-backed chickadee (Poecile rufescens) were sorted into four call note categories, A, C, D, and Dh notes, based on their acoustic structure as observed in sound spectrograms, and evaluated based on the syntactical ordering of the note types within calls. The notes were then analyzed using quantitative measures and it was determined which features have the potential to convey information to discriminate note type, individual, and the geographic origin of the producer. The findings were comparable to previous research of congeners in that chestnut-backed chickadee calls were produced with a relatively fixed syntax and contained similarly structured note types across all geographic regions. Overall this information will form a base for future research on chestnut-backed chickadee vocalizations and will strengthen the foundation for future comparative evolutionary studies.
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    ZENK activation in the nidopallium of black-capped chickadees in response to both conspecific and heterospecific calls
    (2014) Avey, Marc T.; Bloomfield, Laurie L.; Elie, Julie E.; Freeberg, Todd M.; Guillette, Lauren M.; Hoeschele, Marisa; Lee, Homan; Moscicki, Michele; Sturdy, Christopher B.
    Neuronal populations in the songbird nidopallium increase in activity the most to conspecific vocalizations relative to heterospecific songbird vocalizations or artificial stimuli such as tones. Here, we tested whether the difference in neural activity between conspecific and heterospecific vocalizations is due to acoustic differences or to the degree of phylogenetic relatedness of the species producing the vocalizations. To compare differences in neural responses of black-capped chickadees, Poecile atricapillus, to playback conditions we used a known marker for neural activity, ZENK, in the caudal medial nidopallium and caudomedial mesopallium. We used the acoustically complex ‘dee’ notes from chick-a-dee calls, and vocalizations from other heterospecific species similar in duration and spectral features. We tested the vocalizations from three heterospecific species (chestnut-backed chickadees, tufted titmice, and zebra finches), the vocalizations from conspecific individuals (black-capped chickadees), and reversed versions of the latter. There were no significant differences in the amount of expression between any of the groups except in the control condition, which resulted in significantly less neuronal activation. Our results suggest that, in certain cases, neuronal activity is not higher in response to conspecific than in response to heterospecific vocalizations for songbirds, but rather is sensitive to the acoustic features of the signal. Both acoustic features of the calls and the phylogenetic relationship between of the signaler and the receiver interact in the response of the nidopallium.