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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Jak se ze strnada obecného stal Kiwi: příběhy zrozené na pomezí bioakustiky a ekologie invazí / How the Yellowhammer became a Kiwi: stories hatched at the field margins of bioacoustics and invasion ecology

Pipek, Pavel January 2017 (has links)
The presented thesis exploits the introduction of the yellowhammer (Emberiza citrinella) to New Zealand to study the cultural evolution of birdsong dialects in exotic populations after 140 years of complete isolation from the original source populations in Great Britain. The data are interpreted with detailed knowledge of yellowhammer past in New Zealand and of the global (Europe) and regional (Czech Republic) distribution of yellowhammer dialects. Yellowhammer song is simple and males have very limited repertoire. Since the 19th cen- tury it is known that despite its simplicity the song exhibits fascinating geographical variation; the males share the terminal notes to create mosaic-like distribution of dialects. Although this phenomenon has been known for decades and thoroughly studied, many questions remain. One of them is a suspected border between "western" and "eastern" groups of dialects. By combining information about the dialect distributions obtained from works of previous researchers with recordings from online repositories and archives we demonstrate that these groups do not create macrogeographical patterns (Chapter 6). The citizen-science project "Dialects of the Czech Yellowhammers" involved Czech cit- izens in mapping the distribution of yellowhammer dialects in the Czech territory....
32

Assessing use of passive acoustic detection to document behavior of two sympatric pomacentrid species

Pilzer, Sarah Jean 12 March 2016 (has links)
Videotape and audio recordings of a patch reef in Ant Atoll, Pohnpei, Micronesia were analyzed for the presence of bioacoustic activity produced by species of the teleost family Pomacentridae. The acoustic parameters of fish calls were measured and then identified as belonging to either Amphiprion melanopus or Stegastes nigricans. Visual and statistical methods of analysis were combined to compare the calls of the two species and to test for measurable differences in the acoustic parameters of their calls. Soundscape data showed similar patterns to previously observed tropical reef environments. Fish produced single or multi-pulsed calls in the frequency range of 0-1000 Hz that were often accompanied by observable behaviors such as a chases and displays of dominance. Results indicated that the species on this atoll produce similar calls that cannot be distinguished using acoustic data alone. Visual confirmation was necessary for definitive identification of sound producers and in many cases was not possible beyond the family level. Implications for passive acoustic monitoring are that acoustic data collection alone may be able to capture fish abundance but may not be sufficient to fully capture species richness in regions where populations of closely related fish have similar signals.
33

Vibroacoustic Response of the Tympanic Membrane to Hyoid-borne Sound Generated During Echolocation in Bats

Snipes, Chelsie 01 May 2023 (has links) (PDF)
The hyoid apparatus in laryngeally echolocating bats forms a mechanical connection between the larynx and auditory bullae and has been hypothesized to transfer the outgoing echolocation call to the middle ear during echolocation call emission. We used µCT data to build models of the hyoid apparatus and middle ear from six species of bats and used finite element modeling (FEM) to measure the vibroacoustic response of the tympanic membrane due to hyoid-borne sound generated during echolocation. We found that hyoid-borne sound in all six species stimulated the eardrum within a range likely heard by bats. Although there were minor differences at frequencies above 60kHz, there were no obvious morphological explanations to account for it. This suggests that variation in the morphology of the hyoid apparatus in laryngeally echolocating bats is likely driven by other functions associated with the hyoid.
34

East Tennessee Spatial and Temporal Species-Specific Bat Activity Patterns

Morelock, Seth 01 May 2023 (has links) (PDF)
Determining the activity among species-specific bat populations within specific habitat selections can help contribute to the conservation of Appalachian bat species. This study examines the differences in species-specific bat activity patterns between three ponds of variable sizes and a southeast-facing open field with a wooded edge. Four Song Meter SM4BAT FS bioacoustics detectors were used on a 15-acre property in Fall Branch, TN, with a wildlife acoustics detector being placed at three ponds and one field. There were three stages of data collection for this study which all took place during 2023. The first stage was during the spring (March 18th – May 18th), the second stage was during the summer (June 21st – August 27th), and the third stage was during the fall (September 26th – October 26th). Acoustic recordings were analyzed through SonoBat to classify them to species level using a recording call quality threshold of ≥ 95%. An identification likelihood of ≥ 90% yielded 36,308 calls assigned to a particular species/genus. The acoustic detectors detected eight bat species and the Myotis genus throughout the study. Species identified include Rafinesque's big-eared bat (Corynorhinus rafinesquii), big brown bat (Eptesicus fuscus), hoary bat (Lasiurus cinereus), silver-haired bat (Lasionycteris noctivagans), eastern red bat (Lasiurus borealis), evening bat (Nycticeius humeralis), tricolored bat (Pipistrellus subflavus), Mexican free-tailed bat (Tadarida brasiliensis), and species within the Myotis genus. Two chi-square analyses were performed through R to determine if there were significant spatial and temporal species-specific activity patterns between the four sites. Both chi-square analyses resulted in a p-value < 2.2e-16 indicating significant differences in species-specific activity levels between the four sites throughout spring, summer, and fall. This data can help species-specific conservation efforts by understanding bat species’ activity levels at particular habitat selections throughout the fall, summer, and spring seasons.
35

The Vocal Behavior of the American Crow, Corvus brachyrhyncos

Tarter, Robin R. 14 April 2008 (has links)
No description available.
36

monitoR: Automation Tools For Landscape-scale Acoustic Monitoring

Katz, Jonathan Edward 01 January 2015 (has links)
Climate change coupled with land-use change will likely alter habitats and affect state parameters of the animal populations that dwell in them. Affected parameters are anticipated to include site occupancy and abundance, population range, and phenophase cycles (e.g., arrival dates on breeding grounds for migrant bird species). Detecting these changes will require monitoring many sites for many years, a process that is well suited for an automated system. We developed and tested monitoR, an R package that is designed for long-term, multi-taxa automated passive acoustic monitoring programs. monitoR correctly identified presence for black-throated green warbler and ovenbird in 64% and 72% of the 52 surveys using binary point matching, respectively, and 73% and 72% of the 52 surveys using spectrogram cross-correlation, respectively. Of individual black-throated green warbler song events, 73% of 166 black-throated green warbler songs and 69% of 502 ovenbird songs were identified by binary point matching. Spectrogram cross correlation identified 64% of 166 black-throated green warbler songs and 64% of 502 ovenbird songs. False positive rates were We describe a method to identify the probability of survey presence in a template-based automated detection system using known false positive rates for each template. True and false positive detection rates were observed in 146 training surveys. These probabilities were used in a Bayesian approach that discriminates between detections in occupied surveys and unoccupied surveys. We evaluated this approach in 146 test surveys. A total of 1142 Black-throated green warbler (Setophaga virens) songs were observed in the training surveys and test surveys, which we attempted to locate with 3 different binary point matching templates. When only posterior probabilities greater than 0.5 were considered detections, the average ratio of accurate identifications of survey presence to false positive identifications in 500 bootstrapped samples improved from 1.2:1 using a standard score cutoff approach to 2.8:1 using all 3 templates and a likelihood-based discriminator. With the selected score cutoffs the average true positive and false positive rates for the combined three templates were 0.18 and 0.002, respectively. Automated detection methods are increasingly being used for identification and monitoring of landscape-scale responses to climate change and land-use change. Skepticism of automated acoustic monitoring software is largely due to higher false positive and negative error rates than those in traditional human surveys, but the false positive multiple method occupancy model is capable of estimating detection parameters and occupancy state when one method has occasional false positive detections. We test the accuracy of the model when automated detection of black-throated green warbler is mixed with human detection in 4 recorded surveys at 60 sites. Precision and accuracy are evaluated by simulation, and we use the results to optimize future sampling. In simulation, parameter estimates by the multiple method occupancy model are close to those we computed manually when two surveys are manually analyzed. Our results support the use of the multiple method false positive occupancy model to track detection rates in automated monitoring programs.
37

Wavelet analysis of bioacoustic scattering and marine mammal vocalizations

Scheidecker, Elizabeth M. 09 1900 (has links)
Wavelets have been used in numerous geophysical studies but few have examined their applicability to underwater acoustic signals. Wavelet transforms can remove noise from a given time series and allow data analysis at multiple levels of resolution. This unique ability is exercised as a feasible application to the signals in this thesis: a reflected scattered signal from a swimbladder-bearing fish, alewife (Alosa pseudoharengus), and several Odontocetes vocalizations. Both studies reveal that wavelet-based techniques show potential in providing viable information for these acoustic signals despite the lack of statistical analysis. The alewife portion shows a reasonable first order approximation to the absolute target strength and to the time delay correlation caused by the spatial separation of scattering features in the fish. The marine mammal application shows a possible real time method to estimate the mammal's range using the root mean square (RMS) energy of the decomposed signal. Because of wavelet function mismatch, both studies conclude that more extensive research is necessary to develop these techniques into systematic processes.
38

Modeling sound as a non-lethal weapon in the COMBATXXI simulation model / Modeling sound as a non-lethal weapon in the COMBAT 21 simulation model

Grimes, Joseph D. 06 1900 (has links)
Modeling and representing combat and individual soldiers is a complex task. Several factors influence combatant behavior. Using non-lethal methods has become one way for combatant commanders to accomplish their wartime mission. Current the Army and Marine Corps models are not capable of non-lethal weapon replication. The Training and Doctrine Command Analysis Center (TRAC) Monterey California has funded a program of research related to individual combatant representation in modeling and simulation. Modeling non-lethal weapons was identified by TRAC-Monterey as important to better represent actual combat. This thesis used COMBATXXI , a high-resolution, closed-form, stochastic, analytical combat simulation, to replicate non-lethals and study the effects on individual combatants. Existing source code was modified to model the Long Range Acoustic Device (LRAD), the non-lethal platform chosen for this research. LRAD is an acoustic device designed to modify the behavior of personnel with a high intensity warning tone. Once the LRAD capability was developed, a scenario was developed to test the simulated effects of the device. A model was developed to accurately determine behaviors of individual combatants. It was concluded that the implementation of this new non-lethal capability in COMBATXXI improved the model and created a more realistic representation of actual combat conditions.
39

Variation in sound production of the blue catfish, Ictalurus furcatus.

Ghahramani, Zachary 06 August 2010 (has links)
The blue catfish, Ictalurus furcatus, is an invasive species introduced to Virginia in 1974 and is the largest catfish in the United States. Like other Ictalurids, they are capable of producing disturbance calls via stridulation of the pectoral spine. These sounds can be made in air and water, and catfish can be preyed upon by both aerial and underwater predators. I characterized these putative distress calls by recording them in air and in the fish’s natural habitat. Sounds exhibited a wide variation in acoustic parameters relative to fish ontogeny: larger fish produced higher amplitude sounds with lower frequency bands. Sweep and pulse duration increased with fish size, but pulse rate and the number of pulses per sweep decreased. Sounds were more robust in water with a 1400 fold increase in sound pressure compared to air. Frequency response was much more peaked underwater with a considerable amount of high frequency absorption. These sounds appear to be better adapted to water, suggesting that their use in air may be inconsequential.
40

Variação bioacústica das vocalizações do complexo Taraba major (Vieillot, 1816) (Aves Passeriformes: Thamnophilidae) /

Cardoso, Guilherme Sementili January 2016 (has links)
Orientador: Reginaldo José Donatelli / Resumo: A variação vocal é um dos processos que pode levar a especiação em aves. A divergência das características vocais pode levar ao isolamento reprodutivo, uma vez que indivíduos de uma mesma espécie não seriam capazes de reconhecer seus pares que emitam sinais vocais alterados. Sabendo-se que o ambiente exerce uma pressão seletiva importante na transmissão do som, os indivíduos tendem a alterar a estrutura acústica de suas vocalizações, aprimorando a transmissão sonora. Assim, indivíduos de uma mesma espécie que habitam ambientes distintos tendem a apresentar diferenças vocais. Este estudo analisou as vocalizações de T. major oriundas de diversas localidades da região Neotropical para identificar possíveis variações vocais entre as diversas subespécies. Estas variações foram correlacionadas com as coordenadas geográficas, com altitude e com a distribuição espacial das subespécies de T. major. Foram coletadas 119 vocalizações de indivíduos distintos, que tiveram as suas variáveis temporais e espectrais analisadas por meio do espectrograma e do espectro de amplitude, tomando um limite de -42 dB como referência. Tais características foram correlacionadas com as variáveis de latitude, longitude e altitude. Ao total, foram obtidas quatro subespécies. As variáveis foram reduzidas por uma análise de Componente Principal, e depois classificadas por uma Análise de Função Discriminante. A partir das correlações, observou-se uma relação inversa entre características espectrais e temporais.... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The vocal variation is one of the processes that can lead to speciation in birds. The divergence of the vocal features can drive the reproductive isolation, since individuals of the same species will not be able to recognize their mates, which emit altered voice signals. The environment make a significant selective pressure on sound transmission. Thus, individuals tend to change the acoustic structure of their vocalizations to improve the sound transmission. Individuals of the same species that inhabit different environments tend to display vocal differences. This study surveyed the vocalizations of T. major from several locations in the Neotropical region to identify possible vocal variations between different subspecies. These variations were correlated with the geographic coordinates, with altitude and with the spatial distribution of subspecies. We collected 119 vocalizations of different individuals. Vocalizations had their temporal and spectral variables measured through the espectrogram and the power spectrum, taking a -42 dB as reference limit. These variables were correlated with latitude, longitude and altitude. From these same data, we identified the predominant subspecies the location of sampling. In total, four subspecies were obtained. The variables were reduced by a principal component analysis. Then, they were classified by a discriminant function analysis. From the correlations, we found an inverse relationship between spectral and temporal characteristics. F... (Complete abstract click electronic access below) / Mestre

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