This study shows the importance of the basic spectro-temporal song parameters in territorial contests between male songbirds. Chiffchaff and willow warbler were selected as model species for their phylogenetic and ecological similarity, strong territorial behaviour, but very different singing styles. We found that bigger males of both species sing lower pitched songs and that males of both species adjust their behaviour according to song pitch of their rival simulated by playback. Thus, it seems that both species use song pitch to acoustically assess the body size of their rivals. We also show that song length and syllable rate are important features of the song, probably signalling short-term motivation to escalate territorial conflict.

Orientador: Cynthia Peralta de Almeida Prado / Coorientador: Renato Christensen Nali / Banca: Itamar Alves Martins / Banca: Victor Goyannes Dill Orrico / Resumo: A forma de comunicação mais estudada em anuros é a acústica, porém estudos atuais, inclusive com espécies de hábito noturno, demonstram que a comunicação visual também tem grande importância neste grupo. Este trabalho procurou compreender os contextos sociais e estímulos envolvidos na comunicação acústica e visual em Hypsiboas albopunctatus em uma lagoa e brejos no município de Rio Claro, estado de São Paulo. Os objetivos deste estudo foram: (1) verificar a influência do tamanho corporal de machos e temperatura do ar nas características físicas dos cantos (frequência dominante e duração das notas); (2) avaliar a influência do número de machos presentes no coro sobre a taxa de repetição de notas agressivas e de anúncio; (3) avaliar os fatores relacionados à emissão de notas agressivas e de anúncio por meio de observações diretas e experimentos de playback com machos no campo, utilizando diferentes tipos de canto; e (4) avaliar os fatores relacionados à emissão de sinais visuais pelos machos através de observações diretas e playbacks na presença e ausência de um macho intruso. Encontrou-se uma correlação negativa entre a massa corpórea e CRC (comprimento rostro-cloacal) do macho com frequência dominante e duração das notas agressivas, indicando que tais características podem ser utilizadas tanto por rivais quanto por fêmeas para avaliar o tamanho dos machos. Porém, características físicas dos cantos não tiveram correlação com a temperatura do ar, provavelmente devido ao fato dos dados terem sido coletados apenas na estação chuvosa, quando há pouca variação na temperatura. O número de machos no coro influenciou no número de notas agressivas emitidas; machos vocalizando em coros maiores emitiram menos notas agressivas, mostrando um provável aumento de limites de tolerância para... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The most studied form of communication in frogs is the acoustic one, but current studies have shown that visual communication is also important in this group, even in nocturnal species. We aimed to understand the social contexts and stimuli involved in the acoustic and visual communications of Hypsiboas albopunctatus in a pond and wetlands, in the municipality of Rio Claro, São Paulo state, southeastern Brazil. The specific aims of this study were: (1) to verify the influence of male body size and air temperature on the physical characteristics of the calls (dominant frequency and duration of notes), (2) to evaluate the influence of the number of males in the chorus on the repetition rate of aggressive and advertisement notes, (3) to evaluate the factors related to the emission of aggressive and advertisement notes through direct observations and playback experiments carried out in the field, using different types of calls, and (4) to evaluate the factors related to the emission of visual signals by males through direct observations and playback experiments with and without the presence of an intruder male. Dominant frequency and duration of aggressive notes were negatively correlated with male SVL (snout vent length) and body mass, suggesting that these traits might be used by females and rivals to evaluate male size. However, there was no correlation of any physical characteristics of the calls with air temperature, probably because data have been collected during the rainy season, when there is less variation in temperature. The chorus size influenced the number of aggressive notes emitted, i. e., focal males emitted less aggressive notes in larger chorus, which suggest an increase of tolerance regarding calls of neighbor males in larger chorus, allowing the resident males to defend their territories less aggressively, while maximizing... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:30:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-10-31Bitstream added on 2014-06-13T20:00:16Z : No. of bitstreams: 1 ramalho_ces_me_rcla.pdf: 366177 bytes, checksum: c0b4165015a30f1122b7496f028ef432 (MD5) / A forma de comunicação mais estudada em anuros é a acústica, porém estudos atuais, inclusive com espécies de hábito noturno, demonstram que a comunicação visual também tem grande importância neste grupo. Este trabalho procurou compreender os contextos sociais e estímulos envolvidos na comunicação acústica e visual em Hypsiboas albopunctatus em uma lagoa e brejos no município de Rio Claro, estado de São Paulo. Os objetivos deste estudo foram: (1) verificar a influência do tamanho corporal de machos e temperatura do ar nas características físicas dos cantos (frequência dominante e duração das notas); (2) avaliar a influência do número de machos presentes no coro sobre a taxa de repetição de notas agressivas e de anúncio; (3) avaliar os fatores relacionados à emissão de notas agressivas e de anúncio por meio de observações diretas e experimentos de playback com machos no campo, utilizando diferentes tipos de canto; e (4) avaliar os fatores relacionados à emissão de sinais visuais pelos machos através de observações diretas e playbacks na presença e ausência de um macho intruso. Encontrou-se uma correlação negativa entre a massa corpórea e CRC (comprimento rostro-cloacal) do macho com frequência dominante e duração das notas agressivas, indicando que tais características podem ser utilizadas tanto por rivais quanto por fêmeas para avaliar o tamanho dos machos. Porém, características físicas dos cantos não tiveram correlação com a temperatura do ar, provavelmente devido ao fato dos dados terem sido coletados apenas na estação chuvosa, quando há pouca variação na temperatura. O número de machos no coro influenciou no número de notas agressivas emitidas; machos vocalizando em coros maiores emitiram menos notas agressivas, mostrando um provável aumento de limites de tolerância para... / The most studied form of communication in frogs is the acoustic one, but current studies have shown that visual communication is also important in this group, even in nocturnal species. We aimed to understand the social contexts and stimuli involved in the acoustic and visual communications of Hypsiboas albopunctatus in a pond and wetlands, in the municipality of Rio Claro, São Paulo state, southeastern Brazil. The specific aims of this study were: (1) to verify the influence of male body size and air temperature on the physical characteristics of the calls (dominant frequency and duration of notes), (2) to evaluate the influence of the number of males in the chorus on the repetition rate of aggressive and advertisement notes, (3) to evaluate the factors related to the emission of aggressive and advertisement notes through direct observations and playback experiments carried out in the field, using different types of calls, and (4) to evaluate the factors related to the emission of visual signals by males through direct observations and playback experiments with and without the presence of an intruder male. Dominant frequency and duration of aggressive notes were negatively correlated with male SVL (snout vent length) and body mass, suggesting that these traits might be used by females and rivals to evaluate male size. However, there was no correlation of any physical characteristics of the calls with air temperature, probably because data have been collected during the rainy season, when there is less variation in temperature. The chorus size influenced the number of aggressive notes emitted, i. e., focal males emitted less aggressive notes in larger chorus, which suggest an increase of tolerance regarding calls of neighbor males in larger chorus, allowing the resident males to defend their territories less aggressively, while maximizing... (Complete abstract click electronic access below)

Acoustic communication, used by a wide variety of animals, consists of the signaler, the signal and the receiver. A change in the behaviour of the receiver after reception of the signal is a prerequisite for communication. A response to the signal by the receiver depends on signal recognition and localization of the signal source. These two aspects, namely recognition and localization by the receiver, form the main body of my work. In the mating system of crickets, the males produce advertisement calls to attract silent females to mate. Females need to recognize the conspecific call and localize the male. The tree cricket Oecanthus henryi, due to aspects of its physiology and the environment it inhabits, generates interesting problems concerning these seemingly simple tasks of recognition and localization. In crickets, usually a species-specific sender-receiver match for the call features exists, which aids in recognition. A change in the call carrier frequency with temperature, due to poikilothermy, as seen in O. henryi, may pose a problem for this sender-receiver match. To circumvent this, either the response should shift concomitantly with the change in the feature (narrow tuning) or the response should encompass the entire variation of the feature (broad tuning). I explored the response of O. henryi females to the changing nature of call carrier frequency with temperature. The results showed that O. henryi females are broadly tuned to call carrier frequency. Being broadly tuned I next wanted to explore if within the natural variation in carrier frequency, the females were able to discriminate between frequencies. Females were found not to discriminate between frequencies. Cricket ears being pressure difference receivers are inherently directional, however their directionality is dependent on frequency, which may be affected by the change in carrier frequency due to temperature. Thus I also tested the effect of frequency on the azimuthal localization accuracy. The azimuthal accuracy was not affected by call carrier frequency within the natural range of frequency variability of the species. In south India, O. henryi is found in sympatry with Oecanthus indicus. Reproductive isolation between the two is maintained through calls. Since O. henryi is broadly tuned to frequency, call carrier frequency is unlikely to enable differentiation between conspecific and heterospecific calls. I thus tested whether the temporal features can account for the same. I constructed a quantitative multivariate model of response space of O. henryi incorporating results from various playback experiments. The model predicted high responses for conspecific calls and low responses for heterospecific calls, indicating that temporal features could suffice to discriminate between the two species. The quantitative model could also be used more generally to check responses to other heterospecifics and to compare responses between conspecifics from different populations. O. henryi is found on a bush and thus the female has to navigate in a 3D environment to localize the singing male. Very few studies have explored 3D localization in insects and moreover an algorithm explaining the procedure is missing. I attempted to model the 3D localization capability in O. henryi. To understand the rules behind the localization animals were observed in the wild as well as on a 3D grid in the laboratory and simulations were created to capture the nature of the phonotaxis. Neither a random model nor a deterministic model (which estimated the shortest path) could predict the paths observed in the grid. A less complex Bayesian stochastic model performed better than a more complex one. From the assumptions of the model it was inferred that the animal, for 3D localization, basically performs localization in the azimuthal plane and combines certain simple rules to go up or down. This study has examined receiver tuning in response to change in carrier frequency with temperature, which to my knowledge had not been explored before for insects. In this study I also attempted to create a quantitative multivariate receiver response space through statistical modeling, a method that can be applied in similar studies across taxa in various acoustic communication systems. A detailed Bayesian algorithm to explain 3D localization for an insect was attempted which has also not been attempted before.

Orientador: Tadeu Siqueira / Resumo: A natureza é ruidosa. Passarinhos gorjeiam enquanto o vento silva ao pentear os campos com abelhas e seus zunzuns rondando flores. Desatentos, deixamos de notar uma incrível quantidade de elementos retumbando em nosso entorno. No entanto, cada som parte de uma fonte, deixando uma pista sobre a situação na qual foi produzido. Podemos identificar a espécie de passarinho pelo seu canto, e, quem sabe, revelar a passagem de uma espécie migratória. A imagem de um campo nos é desperta ao escutar o vento soprando por gramíneas, que ressoaria diferente se soprasse por uma floresta. Por conseguinte, podemos registrar a atividade acústica dos organismos e descrever as dinâmicas de ecossistemas através de um conjunto de técnicas oferecidas pelo monitoramento acústico passivo. Além disto, os diversos sons emitidos por animais são produzidos sobretudo para fins reprodutivos e territoriais. Sua produção possui elevado custo energético e influencia se a performance de um organismo resultará em saldo positivo para a perpetuação de seus descendentes. Diante disso, alguns percalços no caminho entre a emissão e a recepção desses sons podem adulterar suas características e inviabilizar seu reconhecimento. Por serem ondas mecânicas, a vegetação pode refratar e absorver elementos dos sons emitidos por animais. Ou ainda, em grandes agregações, como os coros por aves no amanhecer e por anuros e invertebrados ao ocaso, os diversos sons podem gerar interferências. Em ambos os casos, a degradação sonora... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Nature is noisy. Birds chirps while the wind whistle when brushing the fields, with bees buzzing around flowers. Meanwhile, our absence of mind prevents us to notice many elements rumbling on our surroundings. However, each sound has a source that leaves clues about the situation in which it was produced. The songbird can be identified by its song and eventually reveal the passage of a migratory species. The wind blowing through the grass quickly resemble the image of a field that would otherwise sound different if it blew through a forest. Therefore, such acoustic activity of the organisms can be recorded and used to describe ecosystems dynamics through a set of techniques included in passive acoustic monitoring. In addition, sounds emitted by animals are produced mainly for reproductive and territorial purpose. Its production is costly and influences whether the performance of an organisms will lead a positive balance for the perpetuation of its descendants. As such, obstacles on the path between sound emission and reception may distort its characteristics and impair sound recognition. As sound are mechanical waves, vegetation can refract and absorb elements on the acoustic signal, or in large aggregations, such as dawn bird chorus and dusk anuran and invertebrate choruses, an abundance of animal sounds can generate interferences. In both cases, sound degradation may compromise species’ reproductive success. On the contrary, another perspective predicts that such obstacles ... (Complete abstract click electronic access below) / Doutor

In dense mating aggregations, such as insect and anuran choruses, signals produced at the same time can overlap and interfere with one another, reducing the ability of receivers to discriminate between individual signals. Thus, evolution by sexual selection is expected to result in mating signal timing strategies that avoid overlap. Patterns of signal alternation between competing males are commonly observed in leks and choruses across taxa. In some species, however, signalers instead deliberately overlap, or ‘synchronize’, their mating signals with neighboring conspecifics. Given the assumed high cost of reduced mate attraction when signals overlap, mating signal synchronization has remained an evolutionary puzzle. Synchronization may be beneficial, however, if overlapping signals reduce the attraction of nontarget receivers (predator avoidance hypothesis). Synchronized signals could also constructively interfere, increasing female attraction to the mating aggregation (the beacon effect hypothesis). I investigate these functions of synchronized signaling in two species of tree frogs that synchronize their mating calls: the pug-nosed tree frog (<i>Smilisca sila</i>) and the Ryukyu Kajika frog (<i>Buergeria japonica</i>). To examine the trade-offs imposed by call synchronization in each species, I conduct a series of field and laboratory playback experiments on target (female frogs) and nontarget (eavesdropping predators) receivers of frog calls. Results from these experiments support both hypotheses, suggesting that synchronized frog calls can reduce the attraction of predators and attract mates to the chorus. In addition, I found reduced preferences for fine-scale call timings in female <i>S. sila</i> and <i>B. japonica</i>, deviating from the expected preferences observed in many other anuran and non-anuran species. Thus, while males may enjoy multiple benefits from synchronized mating signals, relaxed sexual selection for non-synchronous signals may be key to the evolution and maintenance of mating signal synchrony.

Red grouper (Epinephelus morio) are long-lived, commercially important, soniferous fish belonging to the family Epinephelidae. Found throughout the western North Atlantic and Gulf of Mexico, they are protogynous hermaphrodites, and peak spawning occurs from March through May. Unlike many grouper species, red grouper do not form large spawning aggregations; rather, they form small polygynous groups, and remain in relatively close proximity to rocky depressions excavated in the sandy bottom by males. This excavation activity creates structure and habitat for a wide variety of species, and as a result, red grouper are a keystone species on the West Florida Shelf. While extensive life-history information exists, largely from fishery catches, little is known about sound production or behavior of red grouper in their natural environment. Passive acoustic recordings combined with simultaneous digital video recordings were used to investigate sonic activity and behavior of red grouper on the Steamboat Lumps and Madison-Swanson marine reserves on the West Florida Shelf. Red grouper were found to produce a unique series of low-frequency (180 Hz peak) pulses, consisting of 1-4 brief (0.15 s) broadband pulses and a 0.5-2 s down-swept "buzz" (i.e., short call); occasionally these were followed by a rapid series of 10-50 broadband pulses (i.e., pulse train). Sound production was observed throughout the day and night, but most sounds occurred between sunrise and sunset, with a noticeable increase during late afternoon. Behaviors associated with sound production included territorial displays and courtship interactions, indicating that sound production is likely related to spawning activity. Thus, monitoring red grouper using passive acoustics could be an effective tool in fisheries management and conservation efforts.

No description available.

The Underwater Acoustic (UWA) channel has been an area of interest for many researchers and engineers, but also a very challenging area. Compared to the over-the-air radio frequency (RF) channel, the underwater acoustic channel causes multiple distortions – due to multipath, frequency selectivity, noise, and Doppler – some of which are more severe. The increased distortion causes many techniques and assumptions made for typical RF communication systems to break down. One of the assumptions that breaks down is that the Doppler effect that the signal undergoes can be modelled with a simple shift in frequency, since the signals used to communicate in a UWA channel are effectively wideband. In this work the Doppler Effect that a signal undergoes is modelled as a nonlinear time warp. A procedure is developed to estimate the parameters of the time warp from the observed signal. These time warp parameters are then used to reverse the effect of the time warp. Two different methods for estimating the time warp parameters and correcting the Doppler are compared. The first technique uses sinusoids placed at the beginning and end of the signal to estimate the parameters of the warp that the signal undergoes. The second technique uses sinusoids that are present during the signal to estimate and correct for the warp. The frequencies of the sinusoids are outside of the frequency range used for the transmitted data signal, so there is no interference with the information that is being sent. The transmitted data signal uses Orthogonal Frequency Division Multiplexing (OFDM) to encode the data symbols, but the Doppler Correction technique will in principle work for other kinds of wideband signals as well. The results, which include MATLAB based simulations and over-the-air experiments, show that performance improvements can be realized using the time warp correction model. / Master of Science

Communicating wirelessly underwater has been an area of interest for researchers, engineers, and practitioners alike. One of the main reasons for the slow rate of progress in this area is that the underwater acoustic channel is in general much more hostile — in terms of multipath, frequency selectivity, noise, and the Doppler effect — than the over-the-air radio frequency channel. In this work a time warp based technique which can be used to model time-varying wideband Doppler shifts (as seen in an UWA channel) in MATLAB is proposed. A corresponding procedure to estimate the parameters from observed data, required for inverting the effect of the time warp, is also proposed. Two different Doppler correction methods are compared; both can be used to undo the Doppler effect in measured data from an experiment subject to the wideband Doppler effect. The techniques presented correct for the wideband Doppler effect as if it changed the time scale of the received signal. The first resampling based technique corrects for the average expansion/contraction over a packet, inherently assuming the relative velocity to be constant over the duration of the packet. The second time warp based technique models time-varying Doppler shift. Sinusoids, added to the beginning and end of each packet, are used to estimate the parameters required to invert the effect of the warp. The time warp based methods are demonstrated using Orthogonal Frequency Division Multiplexing (OFDM) signals, but will in principle work for other kinds of wideband signals also. The presented results — using MATLAB based simulations, and over-the-air experiments performed in such a way as to introduce the Doppler effect in the received signals — emphasize the improvements that can be attained by using the time warp based Doppler modeling and correction method. The thesis concludes with suggestions for future work. / Master of Science