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Effect of noise on vocal behaviour, physiological systems and reproductive success in birds

Effect of noise on vocal behaviour, physiological systems and reproductive success in birds

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DORADO-CORREA, Adriana M., 2018. Effect of noise on vocal behaviour, physiological systems and reproductive success in birds [Dissertation]. Konstanz: University of Konstanz

@phdthesis{DoradoCorrea2018Effec-42032, title={Effect of noise on vocal behaviour, physiological systems and reproductive success in birds}, year={2018}, author={Dorado-Correa, Adriana M.}, address={Konstanz}, school={Universität Konstanz} }

2018-04-16T08:15:53Z Effect of noise on vocal behaviour, physiological systems and reproductive success in birds 2018-04-16T08:15:53Z Dorado-Correa, Adriana M. Dorado-Correa, Adriana M. eng Urbanization is considered one of the biggest environmental challenges of our times. One of the consequences of the continuing growth in global urbanization is increasing noise pollution. Indeed, anthropogenic noise is predicted to rise considerably levels in the near future. The concern about an increase in anthropogenic noise is that it has been associated with a series of negative effects for humans and animals. For instance, noise is linked to cognitive and auditory problems in humans. In birds, it has been related to changes in vocal signal traits and changes in breeding and parental care behaviour, among others. Despite the relevance and the consequences of anthropogenic noise for humans and wildlife, the effects of noise on health and fitness of the urban fauna are still little known.<br /><br />In this thesis, I investigate how noise can impact birds through different mechanistic pathways by disrupting communication, by impacting physiological systems via stress, and by interfering with development. I choose birds as model organisms for this topic because many species of birds are common inhabitants of cities and have developed a variety of strategies to adapt to urban habitats. Thus, an investigation about the impact of noise on birds not only contributes to the advancement of basic science, but can have direct relevance for conservation actions aimed at maintaining or increasing biodiversity in urban landscapes. In addition, the similarities between humans and birds such as the effects of environmental conditions on physiological systems and the vocal learning process, may allow us to increase the understanding of the mechanism underlying effects of noise in people exposed to chronic noise.<br /><br />The disruption of vocal communication can have detrimental consequences for birds since they use acoustic signals for a variety of functions including mate attraction, territorial defense, kinship communication, maintenance of social cohesion, and information sharing about food sources and potential predators Environmental noise can cause such as disruption. Consequently, birds have developed strategies to overcome the challenge of communicating in noisy environments. One strategy is known as Lombard effect, in which in response to an increase in the background noise, a signaler increases its vocal amplitude. This effect is well-studied in human speech and has also been reported in other mammals and several bird species and is considered as a basic mechanism for maintaining communication in noise. In some cases, the Lombard effect is accompanied by additional changes in signal parameters, such as increased frequency. To date, only three out of eight major avian clades have been studied, therefore the evolution of the Lombard effect and other related vocal adjustments in birds are still unclear. In chapter I.1, I report the first evidence for the Lombard effect in an anseriform bird, the mallard duck (Anas platyrhynchos). Linked to the Lombard effect, ducklings also increased the peak frequency of their calls in noise, however, they did not change any of the others measured parameters. This evidence supports the hypothesis that all extant birds use the Lombard effect to solve the common problem of maintaining communication in noise. Thus, Lombard effect is an ancestral trait shared among all living avian taxa, which strongly suggests that it has evolved more than 70 million years ago within that group. At the same time, our data suggest that parameter changes associated with the Lombard effect follow more complex patterns, with marked differences between taxa, some of which might be related to proximate constraints. In addition to changing certain traits of the vocalizations, birds can also shift the time of singing behaviour in presence of noise. For instance, birds in cities start to sing earlier in the morning than birds in the rural areas. Some studies have attributed these temporal shifts to increased levels of light pollution, while other studies suggest that the shifts are linked to noise pollution. However, all previous studies have taken place in temperate zones. In contrast to temperate birds, tropical birds experience little seasonal variation in day length and may be less dependent on light intensity as a modifier for reproductive behaviours such as song. To test whether noise or light pollution has an impact on the dawn chorus of a tropical bird, in chapter I.2 I investigated the singing behaviour of rufous-collared sparrows (Zonotrichia capensis) in Bogota, Colombia, at two times during the year. The results show that birds start to sing earlier in places with high noise levels. On the other hand, light pollution did not have a significant effect on song timing. Birds may begin to sing earlier in noisy areas to avoid acoustic masking by traffic that peaks later in the morning. These results also suggest that some tropical birds may be less sensitive to variations in day length and thus less sensitive to light pollution.<br /><br />Noise not only can impact acoustic communication, it can also have an impact on short and longterm effects on health and fitness of wildlife. To test how chronic noise affects physiology and well-being of birds, I did a series of experiments in breeding zebra finches (Taenopygia guttata) and their offspring. In chapter II, I experimentally investigated the direct and cross-generational effects of traffic noise on telomeres at 21 and 120 days post-hatch. Telomere length is a measure of cellular ageing that is predictive of disease and longevity in humans and other organisms. Birds were exposed to traffic noise at different developmental stages (pre and post-fledging). Noise did not have a significant effect on telomeres when the birds were exposed pre-fledging. On the other hand, birds exposed to noise during the post-fledging stage exhibited faster telomere loss than pre-fledging exposed and control birds. In chapter III, breeding birds were exposed to noise during courtship and nestling period and I measured the impact of noise on the immune system, baseline corticosterone levels, reproductive success and extra-pair paternity as well as the growth rate of the offspring. Although I did not find significant differences in any of the traits measured in breeding birds, I did find that offspring of birds exposed to noise were smaller than offspring in control groups. These results suggest that traffic noise affects birds differently depending on which the developmental stage they were in when they were exposed.<br /><br />Taken together, the evidence of this thesis suggests that noise has a varying impact on traits related to fitness, such as vocal behaviour, longevity, reproductive success and growth rate in birds depending on species identity, ecological factors and developmental stages. The combination of laboratory and field approaches is necessary to understand how the different elements of urbanization, such as noise pollution, are impacting wildlife in the urban areas. 2018 terms-of-use

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