Impactos da estrutura ambiental nas vocalizações de Troglodytes musculus Naumann, 1823 (Aves, Troglodytidae)
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Data
2020-02-19
Autores
Cardoso, Guilherme Sementili [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O canal sonoro é um dos principais meios do comunicação animal. Como o som se propaga pelo ambiente, qualquer onda sonora é passível de ser alterada pelas condições do ambiente onde o emissor se insere. Determinadas características da estrutura do ambiente podem alterar a capacidade de um sinal ser detectado, como cobertura vegetal, condições climáticas, turbulência aérea, entre outros. Assim, o ambiente pode exercer uma pressão seletiva nas estrutura do sinal sonoro, fazendo com que os indivíduos alterem as características de seus sinais para maximizar a propagação do som em determinados ambientes. No contexto atual, a urbanização crescente vem modificando as condições naturais das paisagens sonoras, fazendo com que a estrutura acústica do ambiente também se modifique. Juntamente com a urbanização, a descaracterização das paisagens naturais diminui a cobertura vegetal, cria anomalias térmicas e aumenta o ruído ambiental, tornando o ambiente acústico muito distinto das condições originais. Assim sendo, a urbanização configura-se como um obstáculo importante para a comunicação sonora, principalmente em grupos animais que utilizam o som como mediador de suas atividades biológicas, como as aves. Por isso, faz-se necessário que haja um conhecimento de como o ambiente urbano afeta a estrutura vocal das populações animais que vivem inseridas em tal ambiente. Deste modo, o objetivo desta tese é verificar as possíveis variações vocais entre duas populações disjuntas de Troglodytes musculus, buscando relacionar estas variações à estrutura abiótica do ambiente. Foram analisadas as vocalizações de machos isolados que estavam vocalizando espontaneamente de poleiros expostos em ambientes abertos, evitando que as vocalizações fossem afetadas pela cobertura vegetal, pelas interações sociais e por objetos artificiais. Foram computados três parâmetros importantes dentro das emissões vocais da espécie: a amplitude sonora, a estrutura espectral e a complexidade sonora. Os índices obtidos pelos três parâmetros foram relacionados com a estrutura ambiental e com parâmetros morfométricos dos indivíduos. Por meio destas análises, observa-se que existe uma divergência vocal entre as duas populações. Esta divergência é influenciada principalmente pela absorção atmosférica do som e pelo ruído ambiental originado do tráfego de veículos. De modo geral, a intensidade e a frequência sonora tendem a aumentar com o ruído e com a absorção sonora. Isto indica que a estrutura abiótica do hábitat exerce uma pressão sobre as vocalizações da espécie, fazendo com que a expressão vocal seja adaptada para as condições ambientais em que o indivíduo se insere.
The sound channel is one of the main media of animal communication. As sound travels through the environment, any sound wave can be altered by the conditions of the environment in which the emitter is inserted. Certain features of the environmental structure can alter the ability of signal discrimination, such as vegetation cover, weather conditions, and air turbulence, among others. Thus, the environment might exert selective pressure on the sound signal structure, causing alterations on features of the signals to maximize sound propagation in certain environments. In the current context, increasing urbanization has been changing the natural conditions of soundscapes, causing the acoustic structure of the environment to change as well. Along with urbanization, the vegetation cover is reduced, thermal anomalies are created and environmental noise is increased, making the acoustic environment very different from the original conditions. Thus, urbanization is an important obstacle for sound communication, especially in animal groups that use sound as a mediator of their biological activities, such as birds. Therefore, it is necessary to have a knowledge of how the urban environment affects the vocal structure of living animal populations inserted in such environment. Thus, the objective of this thesis is to verify the possible vocal variations between two disjoint populations of Troglodytes musculus, seeking to relate these variations to the abiotic structure of the environment. The vocalizations of isolated males that were spontaneously vocalizing from perches exposed in open environments were analyzed, preventing the vocalizations from being affected by vegetation cover, social interactions and artificial objects. Three important parameters within the vocal emissions of the species were computed: amplitude, spectral structure and sound complexity. The indices obtained by the three parameters were related to the environmental structure and morphometric parameters of the individuals. Through these analyzes, I observed the existence of vocal divergence between the two populations. This divergence is mainly influenced by atmospheric sound absorption and environmental noise from traffic. In general, sound intensity and frequency tend to increase with noise and sound absorption. This indicates that the abiotic structure of the habitat puts pressure on the vocalizations of the species, causing the vocal expression to be adapted to the environmental conditions in which the individual is inserted.
The sound channel is one of the main media of animal communication. As sound travels through the environment, any sound wave can be altered by the conditions of the environment in which the emitter is inserted. Certain features of the environmental structure can alter the ability of signal discrimination, such as vegetation cover, weather conditions, and air turbulence, among others. Thus, the environment might exert selective pressure on the sound signal structure, causing alterations on features of the signals to maximize sound propagation in certain environments. In the current context, increasing urbanization has been changing the natural conditions of soundscapes, causing the acoustic structure of the environment to change as well. Along with urbanization, the vegetation cover is reduced, thermal anomalies are created and environmental noise is increased, making the acoustic environment very different from the original conditions. Thus, urbanization is an important obstacle for sound communication, especially in animal groups that use sound as a mediator of their biological activities, such as birds. Therefore, it is necessary to have a knowledge of how the urban environment affects the vocal structure of living animal populations inserted in such environment. Thus, the objective of this thesis is to verify the possible vocal variations between two disjoint populations of Troglodytes musculus, seeking to relate these variations to the abiotic structure of the environment. The vocalizations of isolated males that were spontaneously vocalizing from perches exposed in open environments were analyzed, preventing the vocalizations from being affected by vegetation cover, social interactions and artificial objects. Three important parameters within the vocal emissions of the species were computed: amplitude, spectral structure and sound complexity. The indices obtained by the three parameters were related to the environmental structure and morphometric parameters of the individuals. Through these analyzes, I observed the existence of vocal divergence between the two populations. This divergence is mainly influenced by atmospheric sound absorption and environmental noise from traffic. In general, sound intensity and frequency tend to increase with noise and sound absorption. This indicates that the abiotic structure of the habitat puts pressure on the vocalizations of the species, causing the vocal expression to be adapted to the environmental conditions in which the individual is inserted.
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Adaptação acústica, Ecoacústica, Drive sensorial, Condições climáticas, Ruído antropogênico, Acoustic adaptation, Ecoacoustics