Urban-associated drivers of song variation along a rural–urban gradient

Narango, Desirée L.; Rodewald, Amanda D.

doi:10.1093/beheco/arv197

Cited by 28 publications

(27 citation statements)

References 75 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While several studies reported positive correlations between breeding bird species richness/ abundance and proximity to noisy roads (reviewed in [1,51]), a recent study attempted to disentangle the effects of traffic noise from the traffic itself and found that roads and vehicles on them explained the negative effects better than the noise per se [51]. Male density may also contribute to changes in song [52] as has been found in urban Japanese great tits [6] and northern cardinals (Cardinalis cardinalis) [53]. However, no correlation between male density and minimum frequency was found in cardinals [53] or Eurasian blackbirds (Turdus merula) [54].…”

Section: Discussionmentioning

confidence: 99%

Higher songs of city birds may not be an individual response to noise

et al. 2017

View full text Add to dashboard Cite

It has been observed in many songbird species that populations in noisy urban areas sing with a higher minimum frequency than do matched populations in quieter, less developed areas. However, why and how this divergence occurs is not yet understood. We experimentally tested whether chronic noise exposure during vocal learning results in songs with higher minimum frequencies in great tits (), the first species for which a correlation between anthropogenic noise and song frequency was observed. We also tested vocal plasticity of adult great tits in response to changing background noise levels by measuring song frequency and amplitude as we changed noise conditions. We show that noise exposure during ontogeny did not result in songs with higher minimum frequencies. In addition, we found that adult birds did not make any frequency or song usage adjustments when their background noise conditions were changed after song crystallization. These results challenge the common view of vocal adjustments by city birds, as they suggest that either noise itself is not the causal force driving the divergence of song frequency between urban and forest populations, or that noise induces population-wide changes over a time scale of several generations rather than causing changes in individual behaviour.

show abstract

Section: Discussionmentioning

confidence: 99%

Higher songs of city birds may not be an individual response to noise

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The continuing publication of potential measuring artefacts may, at least partly, be due to the fact that researchers are still being encouraged to eye-ball acoustic parameters from spectrograms (e.g. Cardoso & Atwell 2012;Job, Kohler & Gill 2016;Narango & Rodewald 2016).…”

Section: Introductionmentioning

confidence: 99%

Measurement artefacts lead to false positives in the study of birdsong in noise

et al. 2017

View full text Add to dashboard Cite

Summary Numerous studies over the past decade have reported correlations between elevated levels of anthropogenic noise and a rise in the minimum frequency of acoustic signals of animals living in noisy habitats. This pattern appears to be occurring globally, and higher pitched signals have been hypothesized to be adaptive changes that reduce masking by low‐frequency traffic noise. However, the sound analysis methods most often used in these studies are prone to measurement errors that can result in false positives. In addition, the commonly used method of measuring frequencies visually from spectrograms might also lead to observer‐expectancy biases that could exacerbate measurement errors. We conducted an experiment to (i) quantify the size and type of errors that result from ‘eye‐balling’ frequency measurements with cursors placed manually on spectrograms of signals recorded in noise and no‐noise conditions, and (ii) to test whether observer expectations lead to significant errors in frequency measurements. We asked 54 volunteers, blind to the true intention of our study, to visually measure the minimum frequency of a variety of natural and synthesized bird sounds, recorded either in noise, or no‐noise conditions. Test subjects were either informed or uninformed about the hypothesized results of the measurements. Our results demonstrate that inappropriate methodology in acoustic analysis can yield false positives with effect sizes as large, or even larger, than those reported in published studies. In addition to these measurement artefacts, psychological observer biases also led to false positives – when observers expected signals to have higher minimum frequencies in noise, they measured significantly higher minimum frequencies than uninformed observers, who had not been primed with any expectation. The use of improper analysis methods in bioacoustics can lead to the publication of spurious results. We discuss alternative methods that yield unbiased frequency measures and we caution that it is imperative for researchers to familiarize themselves both with the functions and limitations of their sound analysis programmes. In addition, observer‐expectancy biases are a potential source of error not only in the field of bioacoustics, but in any situation where measurements can be influenced by human subjectivity.

show abstract

“…the genetic song template [63, 69–71]), or even anatomical or physiological traits that affect song production (e.g. body size [39, 72], or bill morphology [41]). Morphologically-mediated population differences in sound frequency are perhaps less likely because, although urban juncos are slightly smaller than mountain juncos, there is no detectable relationship between body size and song frequency in either of our field populations [73].…”

Section: Discussionmentioning

confidence: 99%

Urban birdsongs: higher minimum song frequency of an urban colonist persists in a common garden experiment

Reichard

Atwell

Pandit

et al. 2019

Preprint

View full text Add to dashboard Cite

21Environmental changes caused by urbanization and noise pollution can have profound 22 effects on acoustic communication. Many organisms use higher sound frequencies in 23 urban environments with low-frequency noise, but the developmental and evolutionary 24 mechanisms underlying these shifts are less clear. We used a common garden 25 experiment to ask whether changes in minimum song frequency observed 30 years 26 after a songbird colonized an urban environment are a consequence of behavioral 27 flexibility or canalized changes that occur early in development. We captured male 28 juvenile dark-eyed juncos (Junco hyemalis thurberi) from two recently diverged 29 populations (urban and mountain) soon after they reached independence (aged 25-40 30 days), raised them in identical indoor aviaries, and studied their songs at an age of 31 three years. We found that the large population difference in minimum frequency 32 observed in the field persisted undiminished in the common garden despite the absence 33 of noise. We also found some song sharing between the common garden and natal field 34 populations, indicating that early song memorization before capture could contribute to 35 the persistent song differences in adulthood. These results are the first to show that 36 frequency shifts in urban birdsong are maintained in the absence of noise by genetic 37 evolution and/or early life experiences. 38 39 40 41 42 Introduction 43Anthropogenic noise can alter the biology of diverse animal taxa at organismal, 44 population, and even community scales [1][2][3][4][5][6][7]. In particular, the low frequency 45 background noise often associated with urbanization can interfere with animal 46 communication and has been associated with changes in acoustic signals that improve 47 sound transmission [8, 9]. One such change that is widely observed in urban 48 environments is increased minimum frequency of acoustic signals, which may be an 49 adaptation to overcome the masking effects of low-frequency noise [10][11][12][13][14][15][16]. Our 50 understanding of the developmental and evolutionary mechanisms that may underlie 51 such changes in acoustic signaling remains limited [9,[17][18][19][20][21][22]. Species such as oscine 52 songbirds that learn their songs are of particular interest due to the potential for cultural 53 evolution and other forms of behavioral plasticity, which can facilitate rapid change in 54 response to anthropogenic noise [23][24][25]. 55Several non-mutually exclusive hypotheses have been proposed to explain 56 changes in song frequency in urban environments [9, 26], including short-term plasticity, 57 ontogenetic effects (early experience), and evolutionary change across generations. 58The plasticity hypothesis argues that frequency shifts are the result of behavioral 59 flexibility in response to the presence or absence of a noise stimulus. Some studies in 60 oscine songbirds have found evidence supporting plasticity either through rapid 61 increases in minimum song frequency [18, 22, 27, 28] or switching to...

show abstract

Urban-associated drivers of song variation along a rural–urban gradient

Cited by 28 publications

References 75 publications

Higher songs of city birds may not be an individual response to noise

Higher songs of city birds may not be an individual response to noise

Measurement artefacts lead to false positives in the study of birdsong in noise

Urban birdsongs: higher minimum song frequency of an urban colonist persists in a common garden experiment

Contact Info

Product

Resources

About