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Bustamante N, Garitano-Zavala Á. Natural Patterns in the Dawn and Dusk Choruses of a Neotropical Songbird in Relation to an Urban Sound Environment. Animals (Basel) 2024; 14:646. [PMID: 38396616 PMCID: PMC10886165 DOI: 10.3390/ani14040646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 02/13/2024] [Accepted: 02/14/2024] [Indexed: 02/25/2024] Open
Abstract
Urbanization is one of the more important phenomena affecting biodiversity in the Anthropocene. Some organisms can cope with urban challenges, and changes in birds' acoustic communication have been widely studied. Although changes in the timing of the daily organization of acoustic communication have been previously reported, there is a significant gap regarding possible variations in song structure between dawn and dusk choruses. Considering that urbanization imposes different soundscapes for dawn and dusk choruses, we postulate two hypotheses: (i) there are variations in song parameters between dawn and dusk choruses, and (ii) such parameters within the city will vary in response to urban noise. We studied urban and extra-urban populations of Chiguanco Thrush in La Paz, Bolivia, measuring in dawn and dusk choruses: song length; song sound pressure level; minimum, maximum, range and dominant frequency; and the number of songs per individual. The results support our two hypotheses: there were more songs, and songs were louder and had larger band widths at dawn than at dusk in urban and extra-urban populations. Urban Chiguanco Thrushes sing less, the frequency of the entire song rises, and the amplitude increases as compared with extra-urban Chiguanco Thrushes. Understanding variations between dawn and dusk choruses could allow for a better interpretation of how some bird species cope with urban challenges.
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Affiliation(s)
- Noelia Bustamante
- Carrera de Biología, Universidad Mayor de San Andrés, La Paz P. O. Box 10077, Bolivia
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2
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Caspi T, Johnson JR, Lambert MR, Schell CJ, Sih A. Behavioral plasticity can facilitate evolution in urban environments. Trends Ecol Evol 2022; 37:1092-1103. [PMID: 36058767 DOI: 10.1016/j.tree.2022.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 08/01/2022] [Accepted: 08/05/2022] [Indexed: 01/12/2023]
Abstract
Plasticity-led evolution is central to evolutionary theory. Although challenging to study in nature, this process may be particularly apparent in novel environments such as cities. We document abundant evidence of plastic behavioral changes in urban animals, including learning, contextual, developmental, and transgenerational plasticities. Using behavioral drive as a conceptual framework, our analysis of notable case studies suggests that plastic behaviors, such as altered habitat use, migration, diurnal and seasonal activity, and courtship, can have faciliatory and cascading effects on urban evolution via spatial, temporal, and mate-choice mechanisms. Our findings highlight (i) the need to incorporate behavioral plasticity more formally into urban evolutionary research and (ii) the opportunity provided by urban environments to study behavioral mechanisms of plasticity-led processes.
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Affiliation(s)
- Tal Caspi
- Department of Environmental Science and Policy, University of California, Davis, Davis, CA, USA.
| | - Jacob R Johnson
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, USA.
| | - Max R Lambert
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, USA; Science Division, Habitat Program, Washington Department of Fish and Wildlife, Olympia, WA, USA
| | - Christopher J Schell
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, USA
| | - Andrew Sih
- Department of Environmental Science and Policy, University of California, Davis, Davis, CA, USA
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3
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Lane SJ, Sewall KB. What About Females? Urban Female Song Sparrows Elevate Aggressive Signaling Compared to Rural. Integr Comp Biol 2022; 62:icac106. [PMID: 35790130 DOI: 10.1093/icb/icac106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The costs and benefits of breeding behaviors are influenced by environmental conditions, and habitat variation can shift the degree to which behaviors are expressed. Novel urban habitats have been shown to differ significantly in disturbances such as noise, light at night, and human presence, as well as resource availability, compared to rural habitats. Perhaps because of these environmental differences, urban males of several species are consistently more aggressive than rural males, raising the hypothesis that greater territorial aggression is beneficial in urban habitats. Though often ignored, female songbirds of many species also perform aggressive territorial behaviors towards conspecifics during the breeding season. For socially monogamous songbirds, this aggression functions to ensure partner fidelity and secure resources for reproduction. Studies of the effects of urbanization on songbird behavior have yet to determine if urban females also express greater territorial aggression. Importantly, energetically demanding behaviors such as territoriality and parental care should constrain one another, leading to behavioral trade-offs during the breeding season. Though territorial aggression and parental care are inversely related in males of several species of songbird, this relationship is understudied in female songbirds, particularly those facing environmental change such as urbanization. In this study, we compared aggressive signaling and a measure of parental care (maternal nest visitation rates) between female song sparrows (Melospiza melodia), living in urban and rural habitats. We hypothesized that female aggressive signaling would be higher in urban environments compared to rural, and negatively correlated with maternal visitation rates. We found that urban females, like males, expressed increased aggressive signaling compared to rural. However, female aggressive signaling was not related to our measure of maternal care, suggesting females aren't facing a trade-off between these two behaviors. Collectively, our results are consistent with the hypothesis that urban habitats promote territorial aggression in female song sparrows. As urbanization continues to spread, understanding the behavioral changes animals employ in urban environments requires studying individuals of different sexes and age classes, and will help us understand how some species are able to cope with human induced rapid environmental change.
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Affiliation(s)
- Samuel J Lane
- Virginia Tech, Department of Biological Sciences, 1405 Perry Street, Blacksburg, Virginia, 24061
| | - Kendra B Sewall
- Virginia Tech, Department of Biological Sciences, 1405 Perry Street, Blacksburg, Virginia, 24061
- Virginia Tech, School of Neuroscience, 1405 Perry Street, Blacksburg, Virginia, 24061
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Cronin AD, Smit JAH, Muñoz MI, Poirier A, Moran PA, Jerem P, Halfwerk W. A comprehensive overview of the effects of urbanisation on sexual selection and sexual traits. Biol Rev Camb Philos Soc 2022; 97:1325-1345. [PMID: 35262266 PMCID: PMC9541148 DOI: 10.1111/brv.12845] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 02/11/2022] [Accepted: 02/16/2022] [Indexed: 12/18/2022]
Abstract
Urbanisation can affect mating opportunities and thereby alter inter- and intra-sexual selection pressures on sexual traits. Biotic and abiotic urban conditions can influence an individual's success in pre- and post-copulatory mating, for example through impacts on mate attraction and mate preference, fertilisation success, resource competition or rival interactions. Divergent sexual selection pressures can lead to differences in behavioural, physiological, morphological or life-history traits between urban and non-urban populations, ultimately driving adaptation and speciation. Most studies on urban sexual selection and mating interactions report differences between urban and non-urban populations or correlations between sexual traits and factors associated with increased urbanisation, such as pollution, food availability and risk of predation and parasitism. Here we review the literature on sexual selection and sexual traits in relation to urbanisation or urban-associated conditions. We provide an extensive list of abiotic and biotic factors that can influence processes involved in mating interactions, such as signal production and transmission, mate choice and mating opportunities. We discuss all relevant data through the lens of two, non-mutually exclusive theories on sexual selection, namely indicator and sensory models. Where possible, we indicate whether these models provide the same or different predictions regarding urban-adapted sexual signals and describe different experimental designs that can be useful for the different models as well as to investigate the drivers of sexual selection. We argue that we lack a good understanding of: (i) the factors driving urban sexual selection; (ii) whether reported changes in traits result in adaptive benefits; and (iii) whether these changes reflect a short-term ecological, or long-term evolutionary response. We highlight that urbanisation provides a unique opportunity to study the process and outcomes of sexual selection, but that this requires a highly integrative approach combining experimental and observational work.
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Affiliation(s)
- Andrew D Cronin
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Judith A H Smit
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Matías I Muñoz
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Armand Poirier
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Peter A Moran
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Paul Jerem
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Wouter Halfwerk
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
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5
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Gomes L, Solé M, Sousa-Lima RS, Baumgarten JE. Influence of Anthropogenic Sounds on Insect, Anuran and Bird Acoustic Signals: A Meta-Analysis. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.827440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Acoustic communication is a way of information exchange between individuals, and it is used by several animal species. Therefore, the detection, recognition and correct understanding of acoustic signals are key factors in effective communication. The priority of acoustic communication is effectiveness rather than perfection, being effective avoids affecting the sound-based communication system of the species. One of the factors that can affect effective communication is the overlap in time and frequency during signal transmission, known as signal masking. One type of sound that can cause masking is anthropogenic noise, which is currently increasing due to urban growth and consequently motorized transportation and machinery. When exposed to anthropogenic noise, animals can use compensatory mechanisms to deal with sound masking, such as the modification of acoustic parameters of their acoustic signal. Here, we performed a meta-analysis investigating whether different taxa have a general tendency for changes in acoustic parameters due to anthropogenic noise, we used taxa and acoustic parameters available in the literature that met the minimum criteria to perform a meta-analysis. We hypothesized that animals exposed to anthropogenic noise use compensation mechanisms, such as changes in dominant, maximum or minimum frequencies, call duration, note duration and call rate to deal with masking. We performed a meta-analysis, which synthesized information from 73 studies comprising 82 species of three taxa: insects, anurans and birds. Our results showed that in the presence of anthropogenic noise, insects did not change the acoustic parameters, while anurans increased call amplitude and birds increased dominant frequency, minimum and maximum frequencies, note duration and amplitude of their songs. The different responses of the groups to anthropogenic noise may be related to their particularities in the production and reception of sound or to the differences in the acoustic parameters considered between the taxa and also the lack of studies in some taxa.
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Winandy GSM, Félix RP, Sacramento RA, Mascarenhas R, Batalha-Filho H, Japyassú HF, Izar P, Slabbekoorn H. Urban Noise Restricts Song Frequency Bandwidth and Syllable Diversity in Bananaquits: Increasing Audibility at the Expense of Signal Quality. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.570420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Anthropogenic noise can interfere with animal behavior through masking of acoustic communication. In response to masking, animals may change their acoustic signals as an apparent adjustment strategy, but this may have a drawback on signal quality. Songs and calls may show noise-dependent changes in frequency and duration, which may yield some masking avoidance, but may also constrain other acoustic parameters that might carry information about the sender. In the present study, we investigated whether noise-dependent reduction in frequency bandwidth or song duration restricted syllable diversity or song elaboration in a Neotropical songbird, the bananaquit (Coereba flaveola). We show that bananaquits sing higher frequency songs, of narrower bandwidth, in noisier territories, independent of variation in territory density, without significant variation in song duration. We also show that songs with higher minimum frequencies, narrower bandwidths, and shorter durations have on average a lower number of syllable types and higher syllable rates. This finding is in line with an acoustic restriction and may reflect a functional trade-off between audibility and signal value: higher frequencies may be more audible but less elaborate songs may weaken the message of sender quality. Consequently, noise pollution may not only alter avian communities, but also shape acoustic diversity and processes of sexual selection in urban environments.
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7
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The role of learning, acoustic similarity and phylogenetic relatedness in the recognition of distress calls in birds. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.02.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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8
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Winandy GSM, Japyassú HF, Izar P, Slabbekoorn H. Noise-Related Song Variation Affects Communication: Bananaquits Adjust Vocally to Playback of Elaborate or Simple Songs. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2020.570431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Birds communicate through acoustic variation in their songs for territorial defense and mate attraction. Noisy urban conditions often induce vocal changes that can alleviate masking problems, but that may also affect signal value. We investigated this potential for a functional compromise in a neotropical songbird: the bananaquit (Coereba flaveola). This species occurs in urban environments with variable traffic noise levels and was previously found to reduce song elaboration in concert with a noise-dependent reduction in song frequency bandwidth. Singing higher and in a narrower bandwidth may make their songs more audible in noisy conditions of low-frequency traffic. However, it was unknown whether the associated decrease in syllable diversity affected their communication. Here we show that bananaquits responded differently to experimental playback of elaborate vs. simple songs. The variation in syllable diversity did not affect general response strength, but the tested birds gave acoustically distinct song replies. Songs had fewer syllables and were lower in frequency and of wider bandwidth when individuals responded to elaborate songs compared to simple songs. This result suggests that noise-dependent vocal restrictions may change the signal value of songs and compromise their communicative function. It remains to be investigated whether there are consequences for individual fitness and how such effects may alter the diversity and density of the avian community in noisy cities.
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10
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LaZerte SE, Slabbekoorn H, Otter KA. A field test of the audibility of urban versus rural songs in mountain chickadees. Ethology 2019. [DOI: 10.1111/eth.12876] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stefanie E. LaZerte
- Natural Resources and Environmental Studies University of Northern British Columbia Prince George British Columbia Canada
- John R. Brodie Science Centre, Department of Biology Brandon University Brandon Manitoba Canada
| | - Hans Slabbekoorn
- Behavioural Biology, Institute of Biology Leiden University Leiden The Netherlands
| | - Ken A. Otter
- Natural Resources and Environmental Studies University of Northern British Columbia Prince George British Columbia Canada
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11
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Sandoval L, Juárez R, Villarreal M. Different Messages are Transmitted by Individual Duet Contributions and Complete Duets in a Species with Highly Overlapped Duets. ACTA ACUST UNITED AC 2018. [DOI: 10.2174/1874453201811010056] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Duet function hypotheses have been mostly studied in bird species that produce duets with male and female solo songs. However, in order to understand if patterns of duet function are similar across all duetting species, it is highly necessary to test the duet function hypotheses in species that produce duets with vocalizations other than solo songs.
Objective:
We studied the responses of territorial pairs to each sex’s individual duet contribution and complete duets in a species that produces duets with a vocalization other than male and female solo songs.
Methods:
We conducted a playback experiment where we presented duet contributions of each sex to three populations of White-eared Ground-sparrows (Melozone leucotis) in Costa Rica, during this species’ breeding season in 2016.
Results:
The responses to complete duets were stronger than those to each sex’s duet contribution, suggesting that complete duets and each sex’s duet contribution have different functions. Complete duets are used to protect resources from intruders (supporting the resource defense hypothesis), and to prevent the partner from being usurped by intruders (supporting the mate-guarding hypothesis). Males used solo songs in response to female duet contributions, and this may work to attract intruder females (increasing the probability of extra-pair copulation). Males also use solo songs in response to male duet contributions, which may work as a signal to repel intruder males and guard their female. In this case, where mate attraction occurs with a completely different type of vocalization than used for duetting, we found a clear pattern of a double agenda for males when a territorial intrusion occurs.
Conclusions:
This study provides strong support for the dual function hypothesis in duets and reveals conflicting selective pressures between pair members relative to each hypothesis.
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12
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Thompson KA, Rieseberg LH, Schluter D. Speciation and the City. Trends Ecol Evol 2018; 33:815-826. [DOI: 10.1016/j.tree.2018.08.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 08/18/2018] [Accepted: 08/22/2018] [Indexed: 12/30/2022]
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13
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Subspecies status and methods explain strength of response to local versus foreign song by oscine birds in meta-analysis. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.05.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Bermúdez-Cuamatzin E, López-Hernández M, Campbell J, Zuria I, Slabbekoorn H. The role of singing style in song adjustments to fluctuating sound conditions: A comparative study on Mexican birds. Behav Processes 2018; 157:645-655. [PMID: 29656093 DOI: 10.1016/j.beproc.2018.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 03/13/2018] [Accepted: 04/09/2018] [Indexed: 12/24/2022]
Abstract
Many bird species adjust their songs to noisy urban conditions by which they reduce masking and counteract the detrimental impact on signal efficiency. Different species vary in their response to level fluctuations of ambient noise, but it remains unclear why they vary. Here, we investigated whether noise-dependent flexibility may relate to singing style and signal function of the flexible acoustic trait. Species with highly variable songs may generally be more flexible and strongly repetitive singers may be more limited to stray from their stringent patterns. We exposed males of four passerine species with contrasting singing styles (repertoire size, immediate or eventual variety singing and syllable diversity) to three experimental sound conditions: 1) continuous urban noise; 2) intermittent white noise and 3) conspecific song playback. We found no spectral or temporal changes in response to experimental noise exposure in any of the four species, but significant temporal adjustment to conspecific playback in one of them. We argue that the consistency in song frequency and timing may have signal value, independent of singing style, and therefore be an explanation for the general lack of noise-dependent flexibility in the four species of the current study.
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Affiliation(s)
- Eira Bermúdez-Cuamatzin
- Centro de Investigaciones Biológicas, Área Académica de Biología, Universidad Autónoma del Estado de Hidalgo, Km. 4.5 carretera Pachuca-Tulancingo s/n, Col. Carboneras, Mineral de la Reforma, Hidalgo, C.P. 42184, Mexico; Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands.
| | - Maricela López-Hernández
- Facultad de Ciencias, Universidad Nacional Autónoma de México, A.P. 70-275, C.P. 04510, México City, México
| | - James Campbell
- Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
| | - Iriana Zuria
- Centro de Investigaciones Biológicas, Área Académica de Biología, Universidad Autónoma del Estado de Hidalgo, Km. 4.5 carretera Pachuca-Tulancingo s/n, Col. Carboneras, Mineral de la Reforma, Hidalgo, C.P. 42184, Mexico
| | - Hans Slabbekoorn
- Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
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Zollinger SA, Slater PJB, Nemeth E, Brumm H. Higher songs of city birds may not be an individual response to noise. Proc Biol Sci 2018; 284:rspb.2017.0602. [PMID: 28794216 DOI: 10.1098/rspb.2017.0602] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/03/2017] [Indexed: 12/17/2022] Open
Abstract
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 (Parus major), 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.
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Affiliation(s)
- Sue Anne Zollinger
- Communication and Social Behaviour Group, Max Planck Institute for Ornithology, 82319 Seewiesen, Germany
| | - Peter J B Slater
- School of Biology, University of St Andrews, St Andrews KY16 9TH, UK
| | - Erwin Nemeth
- Communication and Social Behaviour Group, Max Planck Institute for Ornithology, 82319 Seewiesen, Germany.,BirdLife Austria, 1070 Vienna, Austria
| | - Henrik Brumm
- Communication and Social Behaviour Group, Max Planck Institute for Ornithology, 82319 Seewiesen, Germany
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17
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Lyons J, Mastromonaco G, Edwards DB, Schulte-Hostedde AI. Fat and happy in the city: Eastern chipmunks in urban environments. Behav Ecol 2017. [DOI: 10.1093/beheco/arx109] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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Derryberry EP, Gentry K, Derryberry GE, Phillips JN, Danner RM, Danner JE, Luther DA. White-crowned sparrow males show immediate flexibility in song amplitude but not in song minimum frequency in response to changes in noise levels in the field. Ecol Evol 2017; 7:4991-5001. [PMID: 28690825 PMCID: PMC5496534 DOI: 10.1002/ece3.3037] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 03/15/2017] [Accepted: 04/10/2017] [Indexed: 12/20/2022] Open
Abstract
The soundscape acts as a selective agent on organisms that use acoustic signals to communicate. A number of studies document variation in structure, amplitude, or timing of signal production in correspondence with environmental noise levels thus supporting the hypothesis that organisms are changing their signaling behaviors to avoid masking. The time scale at which organisms respond is of particular interest. Signal structure may evolve across generations through processes such as cultural or genetic transmission. Individuals may also change their behavior during development (ontogenetic change) or in real time (i.e., immediate flexibility). These are not mutually exclusive mechanisms, and all must be investigated to understand how organisms respond to selection pressures from the soundscape. Previous work on white-crowned sparrows (Zonotrichia leucophrys) found that males holding territories in louder areas tend to sing higher frequency songs and that both noise levels and song frequency have increased over time (30 years) in urban areas. These previous findings suggest that songs are changing across generations; however, it is not known if this species also exhibits immediate flexibility. Here, we conducted an exploratory, observational study to ask whether males change the minimum frequency of their song in response to immediate changes in noise levels. We also ask whether males sing louder, as increased minimum frequency may be physiologically linked to producing sound at higher amplitudes, in response to immediate changes in environmental noise. We found that territorial males adjust song amplitude but not minimum frequency in response to changes in environmental noise levels. Our results suggest that males do not show immediate flexibility in song minimum frequency, although experimental manipulations are needed to test this hypothesis further. Our work highlights the need to investigate multiple mechanisms of adaptive response to soundscapes.
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Affiliation(s)
| | | | | | | | - Raymond M. Danner
- Biology DepartmentGeorge Mason UniversityFairfaxVAUSA
- Present address: Department of Biology and Marine BiologyUniversity of North CarolinaWilmingtonNCUSA
| | - Julie E. Danner
- Department of Ecology and Evolutionary BiologyTulane UniversityNew OrleansLAUSA
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LaZerte SE, Slabbekoorn H, Otter KA. Territorial black-capped chickadee males respond faster to high- than to low-frequency songs in experimentally elevated noise conditions. PeerJ 2017; 5:e3257. [PMID: 28462051 PMCID: PMC5410156 DOI: 10.7717/peerj.3257] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 03/31/2017] [Indexed: 11/30/2022] Open
Abstract
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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Affiliation(s)
- Stefanie E LaZerte
- Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, British Columbia, Canada
| | - Hans Slabbekoorn
- Behavioural Biology, Institute of Biology, Leiden University, Leiden, Netherlands
| | - Ken A Otter
- Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, British Columbia, Canada
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Derryberry EP, Danner RM, Danner JE, Derryberry GE, Phillips JN, Lipshutz SE, Gentry K, Luther DA. Patterns of Song across Natural and Anthropogenic Soundscapes Suggest That White-Crowned Sparrows Minimize Acoustic Masking and Maximize Signal Content. PLoS One 2016; 11:e0154456. [PMID: 27128443 PMCID: PMC4851413 DOI: 10.1371/journal.pone.0154456] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 04/13/2016] [Indexed: 11/24/2022] Open
Abstract
Soundscapes pose both evolutionarily recent and long-standing sources of selection on acoustic communication. We currently know more about the impact of evolutionarily recent human-generated noise on communication than we do about how natural sounds such as pounding surf have shaped communication signals over evolutionary time. Based on signal detection theory, we hypothesized that acoustic phenotypes will vary with both anthropogenic and natural background noise levels and that similar mechanisms of cultural evolution and/or behavioral flexibility may underlie this variation. We studied song characteristics of white-crowned sparrows (Zonotrichia leucophrys nuttalli) across a noise gradient that includes both anthropogenic and natural sources of noise in San Francisco and Marin counties, California, USA. Both anthropogenic and natural soundscapes contain high amplitude low frequency noise (traffic or surf, respectively), so we predicted that birds would produce songs with higher minimum frequencies in areas with higher amplitude background noise to avoid auditory masking. We also anticipated that song minimum frequencies would be higher than the projected lower frequency limit of hearing based on site-specific masking profiles. Background noise was a strong predictor of song minimum frequency, both within a local noise gradient of three urban sites with the same song dialect and cultural evolutionary history, and across the regional noise gradient, which encompasses 11 urban and rural sites, several dialects, and several anthropogenic and natural sources of noise. Among rural sites alone, background noise tended to predict song minimum frequency, indicating that urban sites were not solely responsible for driving the regional pattern. These findings support the hypothesis that songs vary with local and regional soundscapes regardless of the source of noise. Song minimum frequency from five core study sites was also higher than the lower frequency limit of hearing at each site, further supporting the hypothesis that songs vary to transmit through noise in local soundscapes. Minimum frequencies leveled off at noisier sites, suggesting that minimum frequencies are constrained to an upper limit, possibly to retain the information content of wider bandwidths. We found evidence that site noise was a better predictor of song minimum frequency than territory noise in both anthropogenic and natural soundscapes, suggesting that cultural evolution rather than immediate behavioral flexibility is responsible for local song variation. Taken together, these results indicate that soundscapes shape song phenotype across both evolutionarily recent and long-standing soundscapes.
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Affiliation(s)
- Elizabeth P. Derryberry
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana, United States of America
| | - Raymond M. Danner
- Biology Department, George Mason University, Fairfax, Virginia, United States of America
| | - Julie E. Danner
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana, United States of America
| | - Graham E. Derryberry
- Museum of Natural Science, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Jennifer N. Phillips
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana, United States of America
| | - Sara E. Lipshutz
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana, United States of America
| | - Katherine Gentry
- Biology Department, George Mason University, Fairfax, Virginia, United States of America
| | - David A. Luther
- Biology Department, George Mason University, Fairfax, Virginia, United States of America
- Smithsonian Migratory Bird Center, Smithsonian Institution, National Zoo, Washington, DC, United States of America
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22
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Luther DA, Phillips J, Derryberry EP. Not so sexy in the city: urban birds adjust songs to noise but compromise vocal performance. Behav Ecol 2015. [DOI: 10.1093/beheco/arv162] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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23
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Kight CR, Swaddle JP. Eastern Bluebirds Alter their Song in Response to Anthropogenic Changes in the Acoustic Environment. Integr Comp Biol 2015; 55:418-31. [DOI: 10.1093/icb/icv070] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Anthropogenic noise is associated with changes in acoustic but not visual signals in red-winged blackbirds. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-1928-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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25
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Moiron M, González-Lagos C, Slabbekoorn H, Sol D. Singing in the city: high song frequencies are no guarantee for urban success in birds. Behav Ecol 2015. [DOI: 10.1093/beheco/arv026] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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26
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Luther D, Magnotti J. Can animals detect differences in vocalizations adjusted for anthropogenic noise? Anim Behav 2014. [DOI: 10.1016/j.anbehav.2014.03.033] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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27
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Touchton JM, Seddon N, Tobias JA. Captive rearing experiments confirm song development without learning in a tracheophone suboscine bird. PLoS One 2014; 9:e95746. [PMID: 24788343 PMCID: PMC4005748 DOI: 10.1371/journal.pone.0095746] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 03/29/2014] [Indexed: 12/01/2022] Open
Abstract
The origin of vocal learning in animals has long been the subject of debate, but progress has been limited by uncertainty regarding the distribution of learning mechanisms across the tree of life, even for model systems such as birdsong. In particular, the importance of learning is well known in oscine songbirds, but disputed in suboscines. Members of this diverse group (∼1150 species) are generally assumed not to learn their songs, but empirical evidence is scarce, with previous studies restricted to the bronchophone (non-tracheophone) clade. Here, we conduct the first experimental study of song development in a tracheophone suboscine bird by rearing spotted antbird (Hylophylax naevioides) chicks in soundproofed aviaries. Individuals were raised either in silence with no tutor or exposed to standardized playback of a heterospecific tutor. All individuals surviving to maturity took a minimum of 79 days to produce a crystallized version of adult song, which in all cases was indistinguishable from wild song types of their own species. These first insights into song development in tracheophone suboscines suggest that adult songs are innate rather than learnt. Given that empirical evidence for song learning in suboscines is restricted to polygamous and lek-mating species, whereas tracheophone suboscines are mainly monogamous with long-term social bonds, our results are consistent with the view that sexual selection promotes song learning in birds.
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Affiliation(s)
- Janeene M. Touchton
- Smithsonian Tropical Research Institute, Balboa, Panama
- Max Planck Institute for Ornithology, Radolfzell, Germany
- * E-mail:
| | - Nathalie Seddon
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Joseph A. Tobias
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, United Kingdom
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28
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Valderrama SV, Molles LE, Waas JR, Slabbekoorn H. Conservation implications of song divergence between source and translocated populations of the North Island Kōkako. J Appl Ecol 2013. [DOI: 10.1111/1365-2664.12094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sandra V. Valderrama
- Department of Biological Sciences; The University of Waikato; Private Bag 3105; Hamilton; 3240; New Zealand
| | - Laura E. Molles
- Department of Ecology, Lincoln University; Burns Building Rm 520; Lincoln 7647; Christchurch; New Zealand
| | - Joseph R. Waas
- Department of Biological Sciences; The University of Waikato; Private Bag 3105; Hamilton; 3240; New Zealand
| | - Hans Slabbekoorn
- Institute of Biology Leiden; Leiden University; Sylviusweg 72 2333BE; PO Box 9505, 2300RA; Leiden; The Netherlands
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29
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Smith TB, Harrigan RJ, Kirschel ANG, Buermann W, Saatchi S, Blumstein DT, de Kort SR, Slabbekoorn H. Predicting bird song from space. Evol Appl 2013; 6:865-74. [PMID: 24062797 PMCID: PMC3779089 DOI: 10.1111/eva.12072] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 03/26/2013] [Indexed: 11/26/2022] Open
Abstract
Environmentally imposed selection pressures are well known to shape animal signals. Changes in these signals can result in recognition mismatches between individuals living in different habitats, leading to reproductive divergence and speciation. For example, numerous studies have shown that differences in avian song may be a potent prezygotic isolating mechanism. Typically, however, detailed studies of environmental pressures on variation in animal behavior have been conducted only at small spatial scales. Here, we use remote-sensing data to predict animal behavior, in this case, bird song, across vast spatial scales. We use remotely sensed data to predict the song characteristics of the little greenbul (Andropadus virens), a widely distributed African passerine, found across secondary and mature rainforest habitats and the rainforest-savanna ecotone. Satellite data that captured ecosystem structure and function explained up to 66% of the variation in song characteristics. Song differences observed across habitats, including those between human-altered and mature rainforest, have the potential to lead to reproductive divergence, and highlight the impacts that both natural and anthropogenic change may have on natural populations. Our approach offers a novel means to examine the ecological correlates of animal behavior across large geographic areas with potential applications to both evolutionary and conservation biology.
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Affiliation(s)
- Thomas B Smith
- Department of Ecology and Evolutionary Biology, University of California Los Angeles Los Angeles, CA, USA ; Center for Tropical Research, Institute of the Environment and Sustainability, University of California Los Angeles Los Angeles, CA, USA
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30
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Slabbekoorn H. Songs of the city: noise-dependent spectral plasticity in the acoustic phenotype of urban birds. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.01.021] [Citation(s) in RCA: 199] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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31
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Sandoval L, Méndez C, Mennill DJ. Different vocal signals, but not prior experience, influence heterospecific from conspecific discrimination. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.02.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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32
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33
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Zollinger SA, Podos J, Nemeth E, Goller F, Brumm H. On the relationship between, and measurement of, amplitude and frequency in birdsong. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.04.026] [Citation(s) in RCA: 162] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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34
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Slabbekoorn H, Yang XJ, Halfwerk W. Birds and anthropogenic noise: singing higher may matter. Am Nat 2012; 180:142-5; author reply 146-52. [PMID: 22673657 DOI: 10.1086/665991] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In a recent theoretical study, Nemeth and Brumm explored the effect of amplitude and frequency variation in birdsongs on signal transmission in forested and noisy urban environments. They argued that "increased song pitch might not be an adaptation" but "an epiphenomenon of urbanization." Here we address the validity of comparing the communication benefits of changes in amplitude and frequency to question the adaptive significance of "urban songs." We believe that their calculations actually confirm considerable high-frequency benefits under noisy urban conditions, between and within species. Hence, we conclude that noise-dependent frequency shifts in urban birds can be adaptive.
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Affiliation(s)
- Hans Slabbekoorn
- Behavioral Biology, Institute of Biology, Leiden University, P.O. Box 9516, 2300 RA, Leiden, The Netherlands.
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35
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Luther DA, Derryberry EP. Birdsongs keep pace with city life: changes in song over time in an urban songbird affects communication. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.01.034] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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36
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Pohl NU, Leadbeater E, Slabbekoorn H, Klump GM, Langemann U. Great tits in urban noise benefit from high frequencies in song detection and discrimination. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2011.12.019] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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37
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Mockford EJ, Marshall RC, Dabelsteen T. Degradation of rural and urban great tit song: testing transmission efficiency. PLoS One 2011; 6:e28242. [PMID: 22174781 PMCID: PMC3236192 DOI: 10.1371/journal.pone.0028242] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 11/04/2011] [Indexed: 11/18/2022] Open
Abstract
Acoustic signals play a fundamental role in avian territory defence and mate attraction. Several studies have now shown that spectral properties of bird song differ between urban and rural environments. Previously this has been attributed to competition for acoustic space as a result of low-frequency noise present in cities. However, the physical structure of urban areas may have a contributory effect. Here we investigate the sound degradation properties of woodland and city environments using both urban and rural great tit song. We show that although urban surroundings caused significantly less degradation to both songs, the transmission efficiency of rural song compared to urban song was significantly lower in the city. While differences between the two songs in woodland were generally minimal, some measures of the transmission efficiency of rural song were significantly lower than those of urban song, suggesting additional benefits to singing rural songs in this setting. In an attempt to create artificial urban song, we mimicked the increase in minimum frequency found several times previously in urban song. However, this did not replicate the same transmission properties as true urban song, suggesting changes in other song characteristics, such as temporal adjustments, are needed to further increase transmission of an avian signal in the city. We suggest that the structure of the acoustic environment, in addition to the background noise, plays an important role in signal adaptation.
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Affiliation(s)
- Emily J. Mockford
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom
| | - Rupert C. Marshall
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom
- * E-mail:
| | - Torben Dabelsteen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
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38
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Hanna D, Blouin-Demers G, Wilson DR, Mennill DJ. Anthropogenic noise affects song structure in red-winged blackbirds (Agelaius phoeniceus). J Exp Biol 2011; 214:3549-56. [DOI: 10.1242/jeb.060194] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Anthropogenic noise can mask animal signals that are crucial for communicating information about food, predators and mating opportunities. In response to noise masking, signallers can potentially improve acoustic signal transmission by adjusting the timing, frequency or amplitude of their signals. These changes can be a short-term modification in response to transient noise or a long-term modification in response to chronic noise. An animal's ability to adapt to anthropogenic noise can be crucial to its success. In this study, we evaluated the effects of anthropogenic noise on the structure of red-winged blackbird song. First, we manipulated the presence of anthropogenic noise by experimentally broadcasting either silence or low-frequency white noise to subjects inhabiting quiet marshes located away from roadsides. Subjects exhibited increased signal tonality when temporarily exposed to low-frequency white noise, suggesting that red-winged blackbirds can alter their signals rapidly in response to sudden noise. Second, we compared songs produced in quiet marshes located away from roadsides with songs produced during quiet periods at roadside marshes that are normally noisy. This allowed us to test whether birds that are exposed to chronic anthropogenic noise exhibit altered song structure during temporarily quiet periods. Subjects residing in roadside marshes that are normally polluted with anthropogenic noise sang songs with increased tonality during quiet periods. Overall, our results show that anthropogenic noise influences the structure of birdsong. These effects should be considered in conservation and wildlife management.
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Affiliation(s)
- Dalal Hanna
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | | | - David R. Wilson
- Department of Biological Sciences, University of Windsor, 401 Sunset Avenue, Windsor, ON, Canada, N9B 3P4
| | - Daniel J. Mennill
- Department of Biological Sciences, University of Windsor, 401 Sunset Avenue, Windsor, ON, Canada, N9B 3P4
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39
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Kirschel ANG, Slabbekoorn H, Blumstein DT, Cohen RE, de Kort SR, Buermann W, Smith TB. TESTING ALTERNATIVE HYPOTHESES FOR EVOLUTIONARY DIVERSIFICATION IN AN AFRICAN SONGBIRD: RAINFOREST REFUGIA VERSUS ECOLOGICAL GRADIENTS. Evolution 2011; 65:3162-74. [DOI: 10.1111/j.1558-5646.2011.01386.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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40
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Crispo E, Moore JS, Lee-Yaw JA, Gray SM, Haller BC. Broken barriers: human-induced changes to gene flow and introgression in animals: an examination of the ways in which humans increase genetic exchange among populations and species and the consequences for biodiversity. Bioessays 2011; 33:508-18. [PMID: 21523794 DOI: 10.1002/bies.201000154] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We identify two processes by which humans increase genetic exchange among groups of individuals: by affecting the distribution of groups and dispersal patterns across a landscape, and by affecting interbreeding among sympatric or parapatric groups. Each of these processes might then have two different effects on biodiversity: changes in the number of taxa through merging or splitting of groups, and the extinction/extirpation of taxa through effects on fitness. We review the various ways in which humans are affecting genetic exchange, and highlight the difficulties in predicting the impacts on biodiversity. Gene flow and hybridization are crucially important evolutionary forces influencing biodiversity. Humans alter natural patterns of genetic exchange in myriad ways, and these anthropogenic effects are likely to influence the genetic integrity of populations and species. We argue that taking a gene-centric view towards conservation will help resolve issues pertaining to conservation and management. Editor's suggested further reading in BioEssays A systemic view of biodiversity and its conservation: Processes, interrelationships, and human culture Abstract.
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Affiliation(s)
- Erika Crispo
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
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41
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Dingle C, Poelstra JW, Halfwerk W, Brinkhuizen DM, Slabbekoorn H. Asymmetric response patterns to subspecies-specific song differences in allopatry and parapatry in the gray-breasted wood-wren. Evolution 2011; 64:3537-48. [PMID: 20666843 DOI: 10.1111/j.1558-5646.2010.01089.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Song divergence between closely related taxa may play a critical role in the evolutionary processes of speciation and hybridization. We explored song variation between two Ecuadorian subspecies of the gray-breasted wood-wren (Henicorhina leucophrys) and tested the impact of song divergence on response behaviors. Songs were significantly different between the two subspecies, even between two parapatric populations 10 km apart. Playback experiments revealed an asymmetric response pattern to these divergent subspecies specific songs; one subspecies responded more to songs of its own subspecies than to the other subspecies' songs, whereas the second responded equally strongly to songs of both subspecies. While song parameters revealed a mixed pattern of divergence between allopatric and parapatric populations, the majority of spectral characteristics showed increased divergence in parapatry, suggestive of character displacement. This increased song divergence in parapatry appeared to affect behavioral responses to playback as discriminating responses were most prominent in parapatry and against parapatric songs. The clear behavioral impact of subspecies-specific song differences supports a potential role for song as an acoustic barrier to gene flow. The asymmetric nature of the responses suggests that song divergence could affect the direction of gene flow and the position of the subspecies-specific transition.
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Affiliation(s)
- Caroline Dingle
- Behavioural Ecology Group, Zoology Department, Cambridge University, Downing Street, Cambridge, CB2 3EJ, United Kingdom.
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