BIOACOUSTICS
Table of Contents: Volume 18
Bioacoustics Volume 18 No 2 (2008)
Bioacoustics Volume 18 No 3 (2009)
M.S. DeVries & R.S. Sikes (2008). Vocalisations of a North American subterranean rodent Geomys breviceps. Bioacoustics 18(1): 1-15
Abstract
Ecological restrictions of the subterranean environment have resulted in sensory adaptations in its inhabitants that limit communication below ground. Adaptations such as degenerate vision and reduced hearing capabilities influence the communicative methods employed by subterranean rodents. Due to the logistic difficulties of investigating life underground, little is known about subterranean rodent communication. Vocal repertoires have been examined in a limited number of subterranean species, but never in North American taxa. We examined vocal communication in Baird’s Pocket Gopher Geomys breviceps, a species indigenous to south central North America. Our results show that this species has a repertoire of 4 audible signals, 2 of which are only emitted during close-contact encounters. Energy of signals was concentrated within the frequency range correlating with pocket gophers’ greatest hearing sensitivity. Results are also consistent with the frequency requirements for efficient transmission in the subterranean environment. Corresponding behavioural contexts suggest that vocal communication is important for facilitating social interaction with G. breviceps. Because the Geomyidae extend the furthest into the fossil record and are exclusively solitary species, this group is of fundamental importance for considering evolution of communication in subterranean rodents.
Keywords: subterranean rodent, pocket gopher, Geomys, acoustic communication, vocalisations
P. J. Fonseca, E. A. Serrão, F. Pina-Martins, P. Silva, S. Mira, J. A. Quartau, O. S. Paulo & L. Cancela (2008). The evolution of cicada songs contrasted with the relationships inferred from mitochondrial DNA (Insecta, Hemiptera). Bioacoustics 18(1): 17-34
Abstract
The molecular phylogeny of nine Palaearctic species of cicadas (Hemiptera, Cicadoidea) was inferred using two mitochondrial DNA genes, Cytochrome Oxidase I and II. The two main groups detected, namely species within Tettigetta and Tympanistalna, as well as the two species investigated in the genus Cicada, are robustly supported across the analytical methods. The structure of the song syllables, generated during single tymbal cycles of males of the analysed group of species is remarkably consistent in these two phyletic lines. This reflects the morphology and the mechanics of the tymbal. However the higher level song patterns, which depend on the activity of the central nervous system and have evolved to advertise receptive mates, do not seem to be consistent with either the inferred molecular topology or the basic tymbal cycle. The observed similarities between the molecular phylogeny and the basic tymbal cycles seem to reflect the basic conservative nature of the tymbal structure, while the discrepancy between the former and the calling song pattern is probably related to the high plasticity of the pattern generator in the central nervous system and dependent on species-specific selection.
Keywords: insect calling songs, sound production, molecular phylogenies, cicadas, cytochrome oxydase
Yehudah L. Werner, Evgeny Chernis & Roni Granot (2008). The call of the Sri Lankan golden gecko Calodactylodes illingworthorum, ecological parallel of the fan-toed geckos, genus Ptyodactylus (Reptilia: Sauria: Gekkonidae). Bioacoustics 18(1): 35-49
Abstract
Based on nine calls of Calodactylodes illingworthorum recorded in the wild in Sri Lanka, the ‘spontaneous’ call of the species is a very rapid series of 4-7 roughly similar chirps. Call parameters are compared to those of Ptyodactylus guttatus of Israel because the species are similar in morphology (size, proportions, digit shape, scutellation, coloration), ecology (rupicolous, nocturnal), and reproductive biology (clutches of two eggs, stuck to rock, in ‘rookeries’). The calls of the two species, despite similarity in basic structure, greatly differ in the number of chirps, chirp repetition rate, total duration, dominant frequency, and relative intensity level. The functional implications of these differences are briefly considered.
Keywords: Calodactylodes illingworthorum, gecko, multiple-chirp call, Ptyodactylus, temporal and spectral analysis, vocalization.
E. J.S. Fox, J. D. Roberts & M. Bennamoun (2008). Call-independent individual identification in birds. Bioacoustics 18(1): 51-67
Abstract
Methods normally used for acoustic individual identification can only compare a single song type, both within and between individuals, to determine identity, i.e. they are call-dependent. Call-independent identification does not involve direct comparison of a particular song type. It can therefore be carried out regardless of the amount of song sharing between individuals, or changes in an individual’s repertoire over time. This wide applicability radically expands the range of situations in which acoustic individual identification can be used. Text-independent recognition is routinely conducted on human speech and in this paper the same techniques, using mel-frequency cepstral coefficients and multilayer perceptrons, were applied to bird song. Call-independent identification accuracies ranged from 54.3-75.7% in three passerine species. To suit bird song better, we modified the feature extraction methods and neural network architecture, resulting in accuracies of 69.3-97.1%. A comparison of call-dependent and call-independent identification showed little difference in accuracy for two species, while the third species had a lower accuracy for the call-independent identification. Our results demonstrate that individual identification from bird song can occur even when direct comparison of a particular song type is not possible.
Keywords: individual recognition, passerine birds, Mel-frequency cepstral coefficients, artificial neural network, call-independent identification
R. Policht, K. Tomášová, D. Holecková, D. Frynta (2008). The Vocal Repertoire in Northern White Rhinoceros Ceratotherium simum cottoni as Recorded in the Last Surviving Herd. Bioacoustics 18(1): 69-96
Abstract
The Northern White Rhinoceros Ceratotherium simum cottoni is a subspecies of the White Rhino that is almost extinct in the wild. We studied the last reproducing herd kept in Zoo Dvur Kralove to describe its vocal repertoire. The calls produced by eight individuals were recorded and analysed as concerned both sound properties and behavioural contexts in which they were emitted. We distinguished 11 calls belonging to four categories: (1) tonal harmonic sounds, (2) puffing sounds, (3) growling sounds, and (4) repetitive sounds. We found an apparent similarity between acoustic parameters of homologous calls recorded in both white rhino subspecies. We further confirmed that the repertoire of white rhino calls is much larger than that reported in other rhino species. We tentatively interpret this finding as an adaptation to increased sociality. Four calls reach the infrasound range; nevertheless, they are probably not used for communication over distance. This is obvious in the case of the grouch call, which contains the highest infrasound component. There are, however, other candidates for such a communication function: the repetitive pant sound, which is not known in other rhino species. We hypothesise that the repetitions may enhance their audibility in the typical open habitats of white rhinos.
Keywords: rhinoceros, acoustic, signals, vocal repertoire, social behaviour
S. S. Gogoleva, I. A. Volodin, E. V. Volodina, L. N. Trut (2008). To Bark or Not To Bark? Vocalization in Red Foxes Selected for Tameness or Aggressiveness Toward Humans. Bioacoustics 18(2): 99-132
Abstract
In this study we classify call structures and compare vocalizations toward humans by captive red foxes Vulpes vulpes, artificially selected for behaviour: 25 domesticated, or “Tame” animals, selected for tameness toward people, 25 “Aggressive” animals, selected for aggression toward people, and 25 “Unselected” control foxes, representing the “wild” model of vocal behaviour. In total, 12,964 calls were classified visually from spectrograms into five voiced (tonal) (whine, moo, cackle, growl and bark), and three unvoiced, or noisy (pant, snort and cough) call types. The classification results were verified with discriminant function analysis (DFA) and randomization. We found that the Aggressive and Unselected foxes produced the same call type sets toward humans, whereas the Tame foxes used distinctive vocalizations toward humans. The Tame and Aggressive foxes had significantly higher percentages of time spent vocalizing than the Unselected, in support of Cohen & Fox (1976) hypothesis that domestication relaxes the selection pressure for silence, still acting in wild canids. Unlike in dogs, the “domesticated” Tame foxes did not show hypertrophied barking toward humans, using instead the cackle and pant. We conclude that the use of a certain call type for communication between humans and canids is species-specific, and not is the direct effect of domestication per se.
Keywords: vocalization, domestication, vocal communication, nonlinear phenomena, articulation, red fox, Vulpes vulpes, Canidae
Paulo A. M. Marques, Luís Vicente & Rafael Márquez (2008). Iberian azure-winged magpie Cyanopica (cyana) cooki nestlings begging calls: call characterization and hunger signalling. Bioacoustics 18(2): 133-149
Abstract
Nestling begging behaviour has long been seen as a signal by which nestlings solicit care from parents and most of the existing evidence provides some support for it being an honest signal. Begging is a multicomponent signal in which both sound and vision components are usually important. Although it is known that begging encodes information about nestling hunger the present knowledge about the specific behavioural features that convey the information is still scarce. The aim of this study was to describe begging calls of Iberian Azure-winged Magpie Cyanopica (cyana) cooki nestlings and examine how information on nestling hunger might be encoded in the begging calls. Nestlings were experimentally submitted to different periods of food deprivation and the call variation within individuals was studied. The young were individually tested and stimulated to beg by simulating parental visits. When subject to increasing food deprivation periods, nestlings increased the response level to simulated parental visits. The study also found that for the studied size differences, nestlings did not differ in their response level. Results confirmed that information on nestlings’ hunger might be encoded in parameters of the calling behaviour. When the food deprivation periods increased, nestlings tended to start begging earlier, begged more often, extended their calling bout and increased the call duration, changing both at the level of the call and vocal begging bout. Overall the results support the view of begging as an honest signal, namely that begging should reflect nestling hunger and that only some call features might encode information about hunger.
Keywords: Azure-winged Magpie, nestling, begging, honest signalling
M. Lamml and B. Kramer (2008). Sound Production in the Territorial Behaviour of the Churchill Petrocephalus catostoma (Mormyridae, Teleostei) from the Upper Zambezi River. Bioacoustics 18(2): 151-158
Abstract
This is the first description of vocalisations produced by the mormyrid species Petrocephalus catostoma from the Upper Zambezi River whilst defending a territory. Agonistic behavioural displays of a dominant male towards a conspecific, such as mutual circling or short attacks, were accompanied by characteristic tonal sounds, termed hoots. The mean hoot duration (43 ± SD 1.8 ms) was longer, and the fundamental frequency (H1, 180 ± SD 4.7 Hz) lower, than in the closely related species Petrocephalus ballayi. P. catostoma vocalised hoots only during intraspecific agonistic interactions, especially those accompanying territorial conflict.
Key words: aggression, electric fish, sound production, territory, vocalisation
N. Kidjo, B. Cargnelutti, B. D. Charlton, C. Wilson & D. Reby (2008). Vocal behaviour in the endangered Corsican Deer, description and phylogenetic implications. Bioacoustics 18(2): 159-181
Abstract
Here we present the first description of the vocal behaviour of the Tyrrhenian subspecies of Red Deer, the Corsican Deer. Vocalisations from calves, hinds and stags were recorded. Their acoustic characteristics were analysed in order to contrast these with published data characterising central European Red Deer hind and calve contact calls and Scottish Red Deer stag mating calls. We found that the vocal repertoire of Corsican Deer was very comparable with that of central European and Scottish Red Deer, with the exception of one call type, the harsh roar, absent in the Corsican Deer repertoire. Because Corsican Deer are the smallest subspecies of Red Deer, we expected calls to be characterised by higher spectral components. However, while male roars did have higher vocal tract resonances, consistent with a shorter vocal tract, we found that the fundamental frequency (F0) was much lower than predicted, in fact the lowest recorded in any studied Red Deer subspecies. We also found a strong sexual dimorphism in F0, with male calls approximately twice as low as female calls, suggesting that the low F0 observed in Corsican male roars is a result of sexual selection for lower-pitched males. The results of this study emphasise the phenotypic originality of Corsican Deer, and strengthen the case for its conservation. We also argue that future studies should compare the vocal behaviour of Corsican Deer with that of other circum-Mediterranean populations.
Keywords: Corsican Deer, Red Deer, vocal repertoire, Cervus elaphus corsicanus, formant frequency, vocal tract
C. P.H. Elemans, K. Heeck & M. Muller (2008). Spectrogram Analysis of Animal Sound Production. Bioacoustics 18(2): 183-212
Abstract
Spectrograms visualise the time-frequency content of a signal. They are commonly used to analyse animal vocalisations. Here, we analyse how far we can deduce the mechanical origin of sound generation and modulation from the spectrogram. We investigate the relationship between simple mathematical events such as transients, harmonics, amplitude- and frequency modulation and the resulting structures in spectrograms. This approach yields not only convenient statistical description, but also aids in formulating hypotheses about the underlying mathematical mechanisms. We then discuss to what extent it is possible to invert our analysis and relate structures in spectrograms back to the underlying mathematical and mechanical events using two exemplary approaches: (a) we analyse the spectrogram of a vocalisation of the Bearded Vulture and postulate hypotheses on the mathematical origin of the signal. Furthermore, we synthesise the signal using the simple mathematical principles presented earlier; (b) we use a simple mechanical model to generate sounds and relate experimentally observed mechanical events to characteristics of the spectrogram. We conclude that although knowledge of sound producing systems increases the explanatory power of a spectrogram, a spectrogram per se cannot present unambiguous evidence about the underlying mechanical origin of the sound signal.
Keywords: Bioacoustics, biomechanics, Fourier analysis, Gypaetus barbatus, Duffing equation
Jérôme Sueur, Thierry Aubin & Caroline Simonis (2008). Equipment Review: Seewave, a free modular tool for sound analysis and synthesis. Bioacoustics 18(2): 213-226
Abstract
We review Seewave, new software for analysing and synthesizing sounds. Seewave is free and works on a wide variety of operating systems as an extension of the R operatingenvironment. Its current 67 functions allow the user to achieve time, amplitude and frequency analyses, to estimate quantitative differences between sounds, and to generate new sounds for playback experiments. Thanks to its implementation in the R environment, Seewave is fully modular. All functions can be combined for complex data acquisition and graphical output, they can be part of important scripts for batch processing and they can be modified ad libitum. New functions can also be written, making Seewave a truly open-source tool.
Christina M. Wesolek, Joseph Soltis, Katherine A. Leighty and Anne Savage. (2009). Infant African Elephant Rumble Vocalizations Vary According to Social Interactions with Adult Females. Bioacoustics 18(3): 227-239
Abstract
Research on African elephant (Loxodonta africana) vocal communication has increased in recent years, yet there has been very little data collected on the vocal production of infant African elephants. Vocalizations were recorded from a group of five adult female African elephants and 3 dependent offspring (1 male and 2 female) at Disney's Animal Kingdom, Florida, U.S.A., using custom-designed audio-recording collars worn by the adult females. We measured both source and filter features of infant ‘rumble’ vocalizations made during affiliative social interactions and after cessation of nursing from adult females. Rumble vocalizations produced in the ‘nurse cessation’ context exhibited an upward shift in formant frequency locations, compared to rumbles produced during the ‘affiliation’ context. Additionally, call duration increased and fundamental frequencies decreased after nurse cessations for the male, but both females showed the opposite acoustic response. When infant rumbles accompanied nurse cessations, nursing was more likely to resume within 30 seconds compared to nurse cessations without vocalizations. These results suggest that infant rumbles associated with cessation of nursing reflect the motivational state of infants and may influence maternal responsiveness.
Keywords: infant begging, maternal care, parental investment, parent-offspring conflict, vocal signalling
Ema Knotková, Silke Veitl, Radim Šumbera, František Sedlácek & Hynek Burda (2009). Vocalization of the silvery mole-rat: comparison of vocal repertoires in subterranean rodents with different social systems. Bioacoustics 18(3): 241-257
Abstract
We examined vocalisations of a solitary subterranean rodent, the Silvery Mole-rat Heliophobius argenteocinereus (Bathyergidae). Seven true vocalisations and one mechanical vocalisation were identified. The main frequencies of the analysed sounds (0.34-13.17 kHz) match to a great extent the frequency range suitable for transmission in underground burrows. Due to the narrow frequency range of vocalisations, motivation is predominantly expressed by the rate of tonality rather than by frequency changes. The vocal repertoire of the Silvery Mole-rat perfectly matches to Morton's MS rules, i.e. that low-frequency and harsh vocalisations indicate hostility whereas high tonal calls signalize appeasement or fear. In comparison with social species, this solitary bathyergid produces fewer calls. It lacks contact and alarm calls, but has a rich repertoire of mating calls (mating ends with duet vocalization of male and female). Acoustic signals seem to play a major role in lowering natural aggressiveness during the mating period.
Keywords: Silvery mole-rat, Bathyergidae, vocal communication, Heliophobius argenteocinereus, MS rules, sociality
J.S. Tripovich, R. Canfield, T. L. Rogers & J.P.Y. Arnould (2009). Individual variation of the Female Attraction Call produced by Australian fur seal pups throughout the maternal dependence period. Bioacoustics 18(3): 259-276
Abstract
Australian fur seals are colonial breeding animals that give birth on crowded rookeries. Females leave their pups unattended for extended periods while they forage at sea. On return to the colony, a mother must relocate her pup amongst the hundreds of other pups. Vocal recognition is thought to play a vital role in maintaining the mother-pup bond. In the present study, four sets of 7 different pups were recorded once each at different times throughout the maternal dependence period. The Female Attraction Call was used to determine whether Australian fur seal pups produce individually distinct calls which could be used as a basis for vocal recognition. Results from three different analyses (PIC, DFA and CART) indicated that the fundamental frequency, number of parts per call, duration, quavering and peak frequency changes at the start, mid-point and end of the call (i.e., along PEAK F1) were important to recognition. In 75% of cases using DFA, the Female Attraction Call was classified to the correct caller, suggesting that there is sufficient stereotypy within individual calls, and sufficient variation between them, to enable vocal recognition by females.
Keywords: Australian fur seals, pups, individual variation, vocalizations, Female Attraction Call
Ilya Volodin, Martin Kaiser, Vera Matrosova, Elena Volodina, Anna Klenova, Olga Filatova & Marina Kholodova. (2009). The Technique of Noninvasive Distant Sexing for Four Monomorphic Dendrocygna Whistling Duck Species by Their Loud Whistles. Bioacoustics 18(3): 277-290
Abstract
Here we present an acoustic approach for reliable sexing in four whistling duck species from the genus Dendrocygna and compare it with molecular and cloacal inspection techniques. In the four examined species, the White-faced Whistling Duck D. viduata, Fulvous Whistling Duck D. bicolor, Cuban Whistling Duck D. arborea and Red-billed Whistling Duck D. autumnalis, sexes are indistinguishable by appearance. However all the four species show strong sexual differences in the structure of their species-specific loud whistles. For 59 examined birds, an acoustic-based sexing showed 100% accordance to the DNA PCR analysis, while the cloacal inspection showed only 89.8% accuracy. The results demonstrate that acoustic sexing represents a feasible alternative to the two traditional methods as a nonabrasive tool for the distant sexing of the four whistling duck species both in captivity and in the wild.
Keywords: sexual dimorphism, call, vocalization, DNA PCR analysis, cloacal inspection, Dendrocygna, Anatidae