BIOACOUSTICSTable of Contents: Volume 13
BIOACOUSTICS
Casamitjana, J. (2002). The vocal repertoire of the Woolly Monkey Lagothrix lagothricha. Bioacoustics 13(1): 1-19
Abstract
A preliminary redefinition of woolly monkey Lagothrix lagothricha basic vocalization repertoire was made from the analysis of the vocalisations from a captive colony of woolly monkeys. Modern bioacoustic methods were used on a woolly monkey group showing complex and species typical behaviour. Spectrograms, percentages of the occurrence of the basic vocalization types, and analyses of eolk vocalisations were made. The results show that six basic vocalization types can be found in this species, and that the eolk type is the most common.
Keywords: vocalization, woolly monkey, Lagothrix lagothricha, contact calls
Christensen-Dalsgaard, J., Ludwig T.A. & Narins, P.M. (2002). Call diversity in an Old World treefrog: Level dependence and latency of acoustic responses. Bioacoustics 13(1): 21-35
Abstract
We studied the calling behaviour of the southeast Asian treefrog Polypedates leucomystax in the field. The spontaneous calling rate of isolated males was less than 3 calls/minute with irregular temporal patterning of their calls. Call diversity was very high with nine different call notes and at least 12 different call types recorded. 49% of the 1344 calls recorded were so-called “normal calls”'. Isolated males produce normal calls almost exclusively, and females were attracted to males that only emitted this call. All other calls appear to mediate male-male interactions. The frogs responded to playbacks at stimulus levels below 70 do SPL by increasing the number and diversity of calls. At higher stimulus levels, the evoked calling rate decreased. The latency between stimulus and response depended on the call type of the response. Some of the call types follow the stimulus with a latency of < 1 s. It is unlikely that the short latency responses in P. leucomystax function to avoid call overlap as reported for other frog species, since in this species calling is infrequent and aperiodic. Instead, short response latencies probably reflect increased levels of aggression directed towards the first caller. Thus, response latency itself may have a signal function.
Keywords: anuran, Rhacophoridae, hearing, aggression, display
Gillespie, D. & Chappell, O. (2002). An automatic system for detecting and classifying the vocalisations of harbour porpoises. Bioacoustics 13(1): 37-61
Abstract
A system for automatically detecting the vocalisations of Harbour Porpoises Phocoena phocoena is described. The system consists of a high frequency hydrophone, an analogue electronics module and software running on a laptop computer. The analogue electronics module uses band-pass filters to split signals from the hydrophone into three frequency bands. Envelope tracing circuitry then converts the high frequency signals in these bands to lower frequencies, which are digitized and then analysed on the computer. Decisions as to which clicks are from porpoises and which are from some other source are made automatically, based on the relative amplitudes of the signal in the three frequency bands anti also on the shape of each detected pulse. If two hydrophones are used, it is possible to measure bearings (subject to a rotational ambiguity about the array axis) to detected clicks based on the difference in arrival time of the signal at each hydrophone.
The system has been implemented in a practical package that can be deployed easily from almost any type of vessel or mooring, giving it a wide range of applications. The software, which is designed to run on a PC compatible laptop computer, contains a number of displays to present the data and to facilitate analysis. Properties of individual detected clicks are stored on the computer's hard drive to give a permanent record of detections and to facilitate off-line analysis of data collected in the field.
Keywords: harbour porpoise, acoustic detection, population survey, data logger.
Rasmussen, R. & Dabelsteen, T. (2002). Song repertoires and repertoire sharing in a local group of blackbirds. Bioacoustics 13(1): 63-76
Abstract
The song repertoires of a local group of blackbird Turdus merula males were determined and quantified with respect to individuality and sharing between neighbours. We focused on the long-ranging, introductory whistle part of the song and its motifs of fixed sequences of sounds. These motifs, whether they are used to start the song or placed centrally in the song, constitute the largest units of song that are repeated in the same way every time they are sung. Blackbird motifs therefore are equivalents of song types in other species. The result shows that one needs to analyse more than 200 songs to estimate a male's repertoire, which averaged 44 different motifs. Relative to other species, this is a medium to large song repertoire. The size of the repertoire of start motifs (on average 32) varied only a little between the individuals, whereas that of central motifs (on average 12) varied rather much between the same individuals, suggesting that they form a potential cue for assess- ment of male quality. The males within the neighbourhood showed a high degree of start motif sharing, which, together with the relatively large repertoires, could be constraining neighbour recognition. However, in most males the possession of a few individually distinctive and frequently repeated motifs could counter such an effect.
Keywords: blackbird, song repertoire, repertoire sharing, individuality, neighbour recognition.
Volodin, I.A. & Volodina, E.V. (2002). Biphonation as a prominent feature of the Dhole Cuon alpinus sounds. Bioacoustics 13(2): 105-120
Abstract
Spectrographic analysis showed that dholes produce sounds with two fundamental frequencies (components): the high-frequency and the low-frequency, which may occur simultaneously or separately. The fundamental frequency of the low-frequency component varied from 0.52 to 1.44 kHz, and that of the high-frequency component from 5.51 to 10.77 kHz. In calls where both the frequencies occurred simultaneously, they were not integer multiples of each other. They also had different frequency modulations and had additional combination frequency bands. These are features of biphonation. Our data showed biphonation occurs in a lot of dhole calls (20 to 92% of the calls, depending on the individual (n=14); average occurrence 44.3%, n=1317 sounds). The occurrence of biphonation did not differ between sexes and ages; however, occurrence of the high component only was significantly higher in subadult animals, whereas the occurrence of the low component only was significantly higher in adults. Based on the sound structures, we discuss probable mechanisms of sound production for both the components in the dhole. For the low component, the normal vocal folds oscillation mechanism is suggested. For the high component, four possible mechanisms of sound production are discussed. We conclude that the vortex-shedding mechanism is the most probable.
Keywords: vocalization, nonlinear phenomena, biphonation, vocal membrane, whistle, Canidae, dhole, Cuon alpinus
Page, B., Goldsworthy, S.D. & Hindell, M.A. (2002). Individual vocal traits of mother and pup fur seals. Bioacoustics 13(2): 121-143
Abstract
This study investigates individual vocal traits in three species of fur seal: Antarctic fur seal Arctocephalus gazella, Subantarctic fur seal A. tropicalis, New Zealand fur seal A. forsteri and their hybrids. The attraction calls of mothers and pups were highly stereotyped within each individual and markedly different between individuals. Pup attraction calls (emitted by females) were more variable between individual A. tropicalis and A. forsteri than between individual hybrids and A. gazella. However, such a pattern was not evident for female attraction calls (emitted by pups). Pup attraction calls and female attraction calls were both generally tonal calls overlain with regions of pulses. Female attraction calls had relatively high fundamental frequencies. The importance of individual vocalisations for mothers and pups is best appreciated in relation to maternal fitness and offspring survival: individual vocalisations are favoured by natural selection as they facilitate rapid reunion when mothers return from foraging trips, ensuring maternal resources are not invested in unrelated pups.
Keywords: Vocalization, Arctocephalus, fur seal, individual recognition
Stadler, J.H. (2002). Evidence for a hydrodynamic mechanism of sound production by courting males of the notchtongue goby, Bathygobius curacao (Metzelaar). Bioacoustics 13(2): 145-152
Abstract
Male gobies of the genus Bathygobius are coniferous during courtship. The mechanism by which the sounds are produced is, however, unknown. Early studies on sound production by males of B. soparator suggested that these sounds are hydrodynamic in nature, being produced by the forcible ejection of water through the gill opening. The mechanism of sound production by the closely related species B. curacao was investigated and three lines of evidence are presented which support the hydrodynamic hypothesis. First, similarities between the sounds produced by courting males and by ejecting water through a pipette demonstrated that hydrodynamic forces nark readily produce such sounds. Second, the behavioural motor patterns occurring during sound production are consistent with the hypothesis that water is being ejected through the gill openings. Finally, morphological examination revealed an apparent lack of specialized features associated with sound production, effectively eliminating stridulating and swim bladder mechanisms. These results represent the strongest evidence to date in support of any proposed mechanism of sound production in tile gobiids.
Keywords: Bathygobius curacao, sound production, hydrodynamic.
Edds-Walton, P.L., Mangiamele, L.A. & Rome, L.C. (2002). Variations of pulse repetition rate in boatwhistle sounds from oyster toadfish Opsanus tau around Waquoit Bay, Massachusetts. Bioacoustics 13(2): 153-173
Abstract
The boatwhistle sound produced by male toadfish during the reproductive season attracts females to the nest site. Boatwhistles consist of a series of rapidly produced, amplitude modulated ‘pulses’ of sound that are generated by specific muscles of the gas bladder. Previous studies have shown that boatwhistle characteristics vary with temperature and geographic location. This study investigated the normal range of variation in boatwhistles produced by males in a northern population of O. tau. Multiple boatwhistles were recorded from individuals at different sites around Waquoit Bay, Massachusetts. Multiple boatwhistles were recorded at different sites to assess the range of variation in boatwhistle production from this population. Pulse repetition rates varied from a low of 125 pulses/sec at 16 ºC to a high of 219 pulses/sec at 21 ºC. Careful examination of recordings from different sites indicated that individuals vary in the durations of their boatwhistles as well as in the pulse repetition rates during the very consistently produced second segment of the call. In particular, pulse repetition rate (PRR) varied significantly (p < 0.001) among most individuals recorded at the same temperatures. Psychophysical testing as well as behavioral choice experiments are needed to assess the relative importance of PRR and spectral cues in species recognition and/or mate choice.
Keywords: advertisement calls, boatwhistles, individual variation, pulse production, amplitude modulation
K. M. Leong, A. Ortolani, K. D. Burks, J. D. Mellen & A. Savage. (2003). Quantifying acoustic and temporal characteristics of vocalisations for a group of captive African elephants Loxodonta africana. Bioacoustics 13(3): 213-231
Abstract
In order to increase understanding of African elephant vocal communication and to standardise the terminology used to describe vocalisations, this study examined acoustic and temporal characteristics of 983 vocalisations from 2 male and 6 female captive African elephants. Recording collars were used to monitor vocalisations and videotape to simultaneously record behaviour, allowing for unambiguous attribution of sounds to individuals, even in close proximity. Eight acoustically distinct categories of calls were defined in terms of structural characteristics; two of these categories are described for the first time. Low-frequency vocalisations containing infrasonic components were predominant in this localised communication context and showed a gradation of variation in acoustic structure and duration. Most calls were part of temporally closed exchanges between individuals and coincided with short-distance interactions. In addition, male-female choruses and non-musth rumbles from males were documented, suggesting that the African elephant vocal repertoire may be more complex than previously reported.
Keywords: African elephant, vocal repertoire, infrasound, vocal strategies
M. Wahlberg, J. Tougaard, B. Møhl. (2003). Localising bitterns Botaurus stellaris with an array of non-linked microphones. Bioacoustics 13(3): 233-245
Abstract
Some animals emit sounds usable for acoustic monitoring of their population size. Such signals should be loud, omni-directional and easy to recognise and localise. Eurasian Bittern Botaurus stellaris mating calls (booms) are known to be loud and probably omni-directional but there is no data on acoustic localisation of this species. We made recordings of bittern booms with a 4-element GPS-linked microphone array, calibrated for absolute sound pressure level measurements. Receiver spacing was 65 to 294 m. The source level was 101 ± 3 dB re 20 μPa @ 1 m. The source level did not vary more than 7 dB for the same boom recorded at two different locations, with angular separations of 3º-27º as seen from the source. The geometric transmission loss was close to spherical, and the excess attenuation was much smaller than what was expected from the prevailing temperature and humidity conditions. The prevailing wind conditions caused sound velocity variations of up to 3%. The source location error was 104 ± 113 m (mean ± 1 s.d.). The prevalence of large location errors was probably caused by problems of discerning the direct path from multipath arrivals of the signal at the receivers and by sound velocity variations.
Keywords: acoustic array, acoustic source location, acoustic census, bittern boom, GPS.
S. K. Darden, S. B. Pedersen & T.Dabelsteen. (2003). Methods of frequency analysis of a complex mammalian vocalisation. Bioacoustics 13(3): 247-263
Abstract
The prevalence of complex acoustic structures in mammalian vocalisations can make it difficult to quantify frequency characteristics. We describe two methods developed for the frequency analysis of a complex swift fox Vulpes velox vocalisation, the barking sequence: (1) autocorrelation function analysis and (2) instantaneous frequency analysis. The autocorrelation function analysis results in an energy density spectrum of the signal’s averaged amplitude and frequency information. This analysis was used for locating possible formant structures and quantifying the energy distribution of single barks in the barking sequence. The instantaneous frequency analysis is applied to individual continuous frequency bands and generates frequency contours with a resolution of a couple of Hertz. It was used to quantify frequency modulation and calculate average frequencies of harmonic bands in individual barks and to estimate fundamental frequencies. This second method of analysis had to be evaluated with spectrographic analysis to gauge its reliability for each band analysed. The algorithms used should make both of these methods applicable to other complex vocalisations.
Keywords: autocorrelation, instantaneous frequency, mammalian vocalisation, sound analysis, Vulpes velox
M. C. Baker, M. S. A. Baker & D. E Gammon (2003). Vocal ontogeny of nestling and fledgling black-capped chickadees Poecile atricapilla in natural populations. Bioacoustics 13(3): 265-296
Abstract
We studied the vocal ontogeny of black-capped chickadees Poecile atricapilla from hatching through approximately age 40 days, at which time the juveniles dispersed from their hatching area. Development of three vocalisations (chick-a-dee call, fee-bee song, gargle call) was monitored by tape recording daily. Spectrographic quantification and comparison were carried out with Sound Analysis software. Developmental changes in offspring vocalisations were compared to the parent birds, allowing a measure of acoustic similarity between adults and young throughout early life. The chick-a-dee call developed all four of its component syllables (ABCD) from a single sound of day-old nestlings, but the four syllables emerged in adult form at different times in ontogeny. The fee-bee song was produced in impressively adult form starting at about age 20 days, with no precursor sounds to indicate gradual emergence. The principal difference between adult and juvenile fee-bee songs was the persistent production of three or four notes by juveniles rather than the adults’ species-typical two notes. Gargle calls appear to develop from “subsong” strings of precursor gargle syllables. Juvenile gargles began to be identifiable at about age 33-35 days but did not match any of the gargle calls of the local adult population. Post-dispersal juveniles may develop gargles that match the gargle types of local birds where they settle.
Keywords: ontogeny, vocalisations, bird calls, black-capped chickadees, Poecile atricapilla
N. Ellinger & W. Hödl (2003). Habitat acoustics of a neotropical lowland rainforest. Bioacoustics 13(3): 297-321
Abstract
The acoustic characteristics of an Amazonian lowland rain forest study site in southern Venezuela was analysed to determine environmental constraints upon acoustic communication. Signal degradation was measured by conducting transmission experiments at different heights above ground level. Measurements of ambient noise served to determine possible communication distances for various times of day, heights above ground level and frequencies. “Sound windows” for acoustic longrange communication were found for low frequencies, calling heights in the midstorey and calling in the morning or during the night. Sound attenuation was affected by height and frequency but not by time of day. Background noise varied remarkably with time of day and frequency and had a greater impact on communication distance than signal attenuation.
Keywords: habitat acoustics, sound transmission, acoustic communication, communication distance, Surumoni, Venezuela, tropical rain forest, Amazonia.