Relative effects of ambient noise and habitat openness on signal transfer for chickadee vocalizations in rural and urban green-spaces

LaZerte, Steffi; Otter, Ken A.; Slabbekoorn, Hans

doi:10.1080/09524622.2015.1060531

Cited by 17 publications

(7 citation statements)

References 65 publications

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“…Pitch shifting probably evolved as a mechanism to allow males to dynamically pitch-match (or avoid being pitchmatched by) rivals [28], but it may pre-adapt them with an efficient coping strategy to avoid signal masking from noise. Transmission experiments show that urban noise overlaps black-capped chickadee songs and has the potential to significantly reduce signal-to-noise ratios [29]. Further, observational and experimental exposure studies show that black-capped chickadees exhibit spectral plasticity in response to anthropogenic noise [30,31] and spectrally shift their songs away from narrow bands of overlapping noise [32].…”

Section: Introductionmentioning

confidence: 99%

Learning to cope: vocal adjustment to urban noise is correlated with prior experience in black-capped chickadees

2016

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Urban noise can interfere with avian communication through masking, but birds can reduce this interference by altering their vocalizations. Although several experimental studies indicate that birds can rapidly change their vocalizations in response to sudden increases in ambient noise, none have investigated whether this is a learned response that depends on previous exposure. Black-capped chickadees (Poecile atricapillus) change the frequency of their songs in response to both fluctuating traffic noise and experimental noise. We investigated whether these responses to fluctuating noise depend on familiarity with noise. We confirmed that males in noisy areas sang higher-frequency songs than those in quiet areas, but found that only males in already-noisy territories shifted songs upwards in immediate response to experimental noise. Unexpectedly, males in more quiet territories shifted songs downwards in response to experimental noise. These results suggest that chickadees may require prior experience with fluctuating noise to adjust vocalizations in such a way as to minimize masking. Thus, learning to cope may be an important part of adjusting to acoustic life in the city.

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Section: Introductionmentioning

confidence: 99%

Learning to cope: vocal adjustment to urban noise is correlated with prior experience in black-capped chickadees

2016

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“…The general noise levels experienced by focal males at each site (local ambient noise) ranged from 56 to 71 (median 65) dB(Z) for sites where we played High/Low playback pairs and from 53 to 71 (median 64) dB(Z) where we played Low/High playback pairs. Previous studies have shown that urban habitat structure has little effect on transmission of chickadee song relative to signal interference by urban noise conditions ( LaZerte, Otter & Slabbekoorn, 2015 ) and that it does not influence spectral adjustment in black-capped chickadees ( LaZerte, Slabbekoorn & Otter, 2016 ). Thus, although we conducted our study across a variety of habitat types to ensure an even sampling, we did not evaluate effects of habitat urbanization.…”

Section: Methodsmentioning

confidence: 99%

“…Pitch-shifting is thus a tool black-capped chickadees can, and do, use to spectrally adjust their vocalizations to higher frequencies in noisy conditions ( Proppe et al, 2012 ; LaZerte, Slabbekoorn & Otter, 2016 ) or to shift away, up or down, from narrow bands of masking noise ( Goodwin & Podos, 2013 ). Shifting to higher frequencies in noisy conditions is presumably adaptive as transmission studies show that black-capped chickadee songs are masked by anthropogenic noise ( LaZerte, Otter & Slabbekoorn, 2015 ). Furthermore, black-capped chickadees do not appear to have an innate tendency to respond more or less to low- versus high-frequency songs; Frequency-matching, instead of absolute frequency, is the important signal in male-male interactions ( Mennill & Otter, 2007 ), while females do not appear to differentiate at all ( Ratcliffe & Otter, 1996 ).…”

Section: Introductionmentioning

confidence: 99%

Territorial black-capped chickadee males respond faster to high- than to low-frequency songs in experimentally elevated noise conditions

LaZerte

Slabbekoorn

Otter

2017

PeerJ

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Low-frequency urban noise can interfere with avian communication through masking. Some species are able to shift the frequency of their vocalizations upwards in noisy conditions, which may reduce the effects of masking. However, results from playback studies investigating whether or not such vocal changes improve audibility in noisy conditions are not clear; the responses of free-ranging individuals to shifted signals are potentially confounded by functional trade-offs between masking-related audibility and frequency-dependent signal quality. Black-capped chickadees (Poecile atricapillus) naturally sing their songs at several different frequencies as they pitch-shift to match conspecifics during song-matching contests. They are also known to switch to higher song frequencies in response to experimental noise exposure. Each male produces both high- and low-frequency songs and absolute frequency is not a signal of aggression or dominance, making this an interesting species in which to test whether higher-frequency songs are more audible than lower-frequency songs in noisy conditions. We conducted playback studies across southern and central British Columbia, Canada, using paired song stimuli (high- vs low-frequency songs, n = 24 pairs) embedded in synthetic background noise created to match typical urban sound profiles. Over the course of each playback, the signal-to-noise ratio of the song stimuli was gradually increased by raising the amplitude of the song stimuli while maintaining background noise at a constant amplitude. We evaluated variation in how quickly and aggressively territorial males reacted to each of the paired stimuli. We found that males responded more quickly to playbacks of high- than low-frequency songs when high-frequency songs were presented first, but not when low-frequency songs were first. This difference may be explained by high-frequency songs being more audible combined with a carry-over effect resulting in slower responses to the second stimulus due to habituation. We observed no difference in overall aggression between stimuli. These results suggest that high-frequency songs may be more audible under noisy conditions.

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“…Mountain chickadees (P. gambeli) sing whistled multi-note songs which vary considerably among populations (Grava, Otter, et al, 2013a;LaZerte, Otter, et al, 2017a), although in most populations consist of one or more high notes followed by several notes at a lower pitch. The song, particularly the lower-pitched elements, can be severely masked by urban noise (LaZerte, Otter, & Slabbekoorn, 2015). In noisy environments (typically urban landscapes), the lowest pitched notes are often higher in frequency than those in quiet areas (LaZerte, Otter, et al, 2017a).…”

Section: Ríosmentioning

confidence: 99%

A field test of the audibility of urban versus rural songs in mountain chickadees

2019

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Anthropogenic noise can mask avian vocalizations, and several urban‐dwelling species adjust frequency or amplitude of vocalizations in ways that appear to compensate for increased noise levels. Playback studies have investigated whether receivers differentiate between signals produced by rural and urban males, but it is difficult to determine whether differential response to stimulus reflects differences in audibility versus perceived differences in male signals/condition that result from urban settlement. Here, we performed paired‐playback trials to determine whether mountain chickadees (Poecile gambeli) differentiate urban versus rural songs when both stimuli were broadcast within noise. For each playback, stimuli were played in short bouts starting at a low signal‐to‐noise ratio and increasing in relative amplitude with each successive bout. If the primary function of adjusted urban songs is propagation in noise, we hypothesized that focal males would respond sooner to urban versus rural playbacks (detect at lower signal‐to‐noise ratios). If urban songs solely encode information about the male's condition (such as increased aggression), then we predicted only a differential aggressive response to playbacks once detected. If urban songs both increase propagation and embed information on male condition, we predicted a combination of both response types. We found no difference in latency to first response in urban versus rural songs, but some evidence for differential aggression to playback dependent on both stimulus type (urban vs. rural) and local ambient noise levels; focal males in noisy (urban) sites responded aggressively to both stimulus types, whereas focal males in quiet (rural) sites responded more aggressively to urban than to rural stimuli. This context‐dependent discrimination may be the result of increased aggression in urban habitats, improved communication in noisy habitats by urban signallers and receivers, or some combination of the two.

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Relative effects of ambient noise and habitat openness on signal transfer for chickadee vocalizations in rural and urban green-spaces

Cited by 17 publications

References 65 publications

Learning to cope: vocal adjustment to urban noise is correlated with prior experience in black-capped chickadees

Learning to cope: vocal adjustment to urban noise is correlated with prior experience in black-capped chickadees

Territorial black-capped chickadee males respond faster to high- than to low-frequency songs in experimentally elevated noise conditions

A field test of the audibility of urban versus rural songs in mountain chickadees

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