In many song birds, song repertoire size correlates with male quality and can vary with age. Many species have pronounced changes in repertoire size and composition especially between first and second season. This holds true also for Common nightingales Luscinia megarhynchos a species with large song type repertoires. One function of such pronounced changes between year one and two might be an adjustment to the ‘popular’ song types in the breeding grounds. As part of a long term field study we investigated whether nightingales adjust their song type repertoires to the song types commonly sung in their breeding population. We analysed nocturnal song of individuals in their first and subsequent breeding season. We compared the repertoire composition of these birds with the ‘popular’ song types in the breeding ground and addressed whether such ‘popular’ song types were permanent, added, or dropped from first to second breeding season of our target birds. Furthermore, we compared repertoire similarity of first year nightingales’ repertoires with the population repertoires to the same measure for these birds in their next year. Our data suggest that nightingales adjusted their singing to the songs in the breeding grounds by maintaining common and frequently sung song types which resulted in increased similarity to the population repertoire. Song type matching among males and female song preferences will be discussed as potential underlying functions of such repertoire adjustment.
Many researchers base their findings upon acoustic features of vocalisms, found by visually inspecting ("eyeballing") spectrograms, or by reading off numbers from software tools without knowing to what signal-processing standard those numbers were determined. Without using a consistent measuring tape, so to speak, the scientific process of reproducing and confirming others' results becomes more problematic, and measurement itself becomes open to bias. We document our improved signal processing algorithms to more accurately determine spectral parameters from vocalisms, in an effort to achieve more precise, reliable and consistent results. We propose a dynamic weighted-harmonic scaling algorithm to measure fundamental frequency. Furthermore, new methods are created to account for frequency modulation in vocalisms, such as periodic warbling and linear chirping. New vocal measurement features become possible, as a result of the new methods. For example, several novel variants of maximum/minimum fundamental frequency, peak frequency, and bandwidth, become available to the researcher. Novel vocal features provide researchers with new possibilities in linking vocalisms to behaviour. Recorded vocalizations of ring-tailed lemurs (Lemur catta) were fed into the algorithms, and the results are presented in comparison to results from traditional analysis techniques. New vocal features made possible by the new methods are correlated with other data including body mass, and their degrees of correlation are presented in order to contrast how correlation-informative the new methods are compared to traditional methods. Current work is presented in creating a freely accessible software program for researchers to apply these methods to their own vocal recordings of primates, as well as other organisms.
I had the privilege to participate in the Austrian biological excursion to Iran between 10th and 22nd June 2007. During this excursion, we first visited lake Alagol, PA Jahan Namah (Elburz mountains) and then Golestan Province and the Golestan National Park, its facilities in Tange Gol, and the mountains around Almeh station. I tried to make contributions to the knowledge of cicadan fauna of these region with the emphasis on bioacoustic data. One of the results was the discovery of the new species Tettigetta golestani in the Golestan national park. The description has been already published*. I recorded also songs of the Cicadatra viridis, which were previously not published and hardly differ from the song of Cicadatra hyalina. Interesting is also detection and recording of the typical song of the “European” Cicadetta montana s. str. in Jahan Namah and Golestan NP. These are the farthest eastern localities proven acoustically for this species. Other species of cicadas recorded and/or collected during this field excursion will be listed in this paper.
*Gogala M., Schedl W., 2008. A new Tettigetta species from Iran and its song (Hemiptera: Cicadidae, Cicadettinae). Advances in Arachnology and Developmental Biology. Papers dedicated to Prof. Dr. Bozidar Curcic. S. E. Makarov & R. N. Dimitrijevic (Eds.). Inst. Zool., Belgrade; BAS, Sofia; Fac. Life Sci., Vienna; SASA, Belgrade & UNESCO MAB Serbia. Vienna - Belgrade - Sofia, Monographs, 12, 395-404.
The howler monkey (Alouatta species) is characterised by the production of howl vocalisations. These howls are suggested to function in territorial demarcation, social mating and resource defence. Preliminary observations of captive housed black howler monkeys (Alouatta caraya) found that the majority of groups do not perform howl vocalisations. To stimulate vocalisations, playback experiments were conducted on 11 groups of captive A. caraya, five pairs and six family groups, in UK zoos. Four acoustic stimuli were tested; howls of other A. caraya, howls of a non-sympatric howler species (A. palliata), the roars of a different primate species, the red ruffed lemur (Varecia rubra), and the low frequency sound of a chainsaw. The lemur calls and chainsaw sounds acted as controls. All four sounds were played on a random schedule, each morning, for six consecutive days for each study group. Responses of the adult male and female in each group were classified as orientation to the speaker location, physical approach towards the speaker and whether a vocal response was performed. A significant effect of sex was found, with males responding more to all stimuli than females. Behavioural responses to all acoustic stimuli were significantly higher when there was more than one howler monkey group housed in the zoo. This effect was most pronounced in female subjects. There were significantly more responses towards the playback of conspecific calls and responses increased with subsequent playback days. This study provides evidence that playback can elicit the performance of natural calls, providing an environment that may promote the welfare of this captive housed primate species.
The Canestrini’s goby Pomatoschistus canestrinii (Ninni) is an endemic sand goby occurring in lagoons and estuaries of the northern Adriatic Sea. Likewise as in other sand gobies, reproduction implies nest acquisition and defence, mate attraction, and repulsion of other male intruders that may try to penetrate the nest and perform sneaking fertilisations of the eggs. Furthermore, sound production has been documented in this species by previous work, occurring both in reproductive and aggressive behavioural contexts. In this paper, sound production and associated behaviours were assessed and compared in pairs spawning in two different experimental situations: 1) Isolated resident males 2) Resident males paired with a smaller male, and therefore exposed to possible nest intrusions. The simultaneous video- and acoustical recording of the spawning behaviour allowed to quantify the intensity of sound production and associated behaviours, that were then compared between the groups of males. Results indicated that the spawning behaviour of the nest-holding male was affected by the presence of a male intruder, as the spawning sequence was repeatedly interrupted by the intrusion attempts. This was reflected in an intense aggression and associated sound production of the nestholding male towards the intruder male, but also in a significant increase of aggressive sounds and aggressive visual displays towards the female. Furthermore, the frequency of a female visual display increased significantly when the male was exposed to nest intruders. By contrast, the overall frequency of pre-spawning sounds did not change between the two situations, although the mean duration of the burst containing the highest number of sounds was higher in the group of males exposed to male intruders that in the isolated spawning males. On the whole, these results indicate that parasitic nest intrusions affect significantly the spawning patterns of the nest-holding males, even in terms of sound rate.
Voice breaking is a process associated with puberty of human males and attends adolescence also in some birds. This phenomenon is well studied in humans, but still is poor studied in birds including cranes. Unanswered are questions about when do cranes start and complete the process, what changes occur in time and frequency vocal parameters throughout it and how they are related to the sex, date of birth and overall body growth. Here we traced the vocal development in 31 cranes from hatching to 1.5 years old relating to increase of body mass and in comparison with voices of 13 conspecific adults. During voice breaking, calls of both sexes contained two independent fundamental frequencies: the high one, that was a retained juvenile frequency, and the low one, that was a newly appeared adult frequency. Before voice breaking, calls contained only the high frequency, while after voice breaking – only the low frequency. Values of both frequencies didn’t overlap and didn’t change during all ontogenesis. Cranes starts voice breaking in 7 month and complete it at 11.5 month on average. The onset of voice breaking coincided with achieving the adult weight, while factors influencing on its completion were not evident. We don’t find any effect of sex and date of birth on the onset and completion of voice breaking. We discuss that in nature the completion of voice breaking could be related to cessation of parental care after the break of a parent-chick bond closely before the beginning of a new breeding season.
Visual and acoustic surveys have shown that endangered North Atlantic right whales overwinter in the waters of the Northeast US. Detailed knowledge of this population’s distribution is critical to reducing anthropogenic mortality events. Passive acoustic studies have confirmed that Stellwagen Bank National Marine Sanctuary (SBNMS) and Jeffreys Ledge are areas of high baleen whale acoustic activity during the winter. Right whales produce three main types of calls, the up-call, gun-shot and tonal calls. However, no thorough assessment has yet been made of whether this call type is the most appropriate one to use. SBNMS has been part of an ongoing passive acoustic study since 2006 and provides an opportunity for understanding the relationship between up-calls and gun-shots for this region. From December 18th 2007 to May 28th 2008 an array of 10 marine acoustic recording units was deployed in SBNMS. An automated detector was used to determine seasonal occurrence of calls. Gun-shots and upcalls occurred throughout the winter period, with gun-shots peaking in January, and up-calls peaking in December. Comparative analyses of up-calls and gun-shots show that they occur simultaneously around 17:00. Gun-shots primarily tended to occur between 16:00 and 4:00, while up-calls primarily occurred between 11:00 and 18:00. Average gun-shot activity was 2.15 calls/min, while average up-call activity was 3.45 calls/min. Future research should be directed towards assessing occurrence of different call types between seasons, and in the south-east US breeding grounds and northern foraging areas.
Within the genus Trox the structure of the stridulation organs does not vary significantly among species. I analysed distress signals in 5 species of the genus Trox F. (T. sabulosus, T. cadaverinus, T. scaber, T. eversmannii and T. puncticollis). Each beetle was held with pincers a few seconds and then released, simulating an attempted predation by a bird. Following this disturbance, the beetle would spontaneously stridulate for several minutes. I was able to recognise various differences with regards to the length of chirps and syllables of these distress signals. These differences appear to be species specific.
Field monitoring of bat species by means of acoustic methods has been the start of the new epoch in the history of bat research. Our aim was to investigate these methods are adaptable to shrew species. We have made sound recordings in the audible range from 6 shrew species in standard environment. In addition we trapped animals and made long field recordings in different natural habitats in Hungary. We applied artificial intelligence methods in Matlab environment for solving different informatic problems. First problem was to recognize automatically shrew calls in the long noisy field recordings. After manual selection of shrew calls we have trained an Artificial Neural Network to collect automatically these calls from recordings. Comparing the acoustic and trapping data it turned out that this acoustic method shows shrew activity in much finer resolution. The second problem was the species identification. Applying Hidden Markov Models we reached at least 70% correct identification. We recognized 2 or 3 different group of calls from different individuals of the same species, which may show us more information about the individuals. We think these automatic methods may serve the better understanding of ethology and ecology of shrews, which may lead making more effective conservation program.
A descended and sexually dimorphic larynx is known only for humans and for a few species of ungulates. The enlarged and descended larynx of adult male Goitred Gazelles Gazella subgutturosa is remarkably mobile. Here we study, whether the vocal ontogenesis in male and female Goitred Gazelles proceeds similarly to those of human adolescents. We recorded nasal calls from 10 male and 13 female Goitred Gazelles captured on the fenced 5000 hectares-territory of Ecocenter "Djeiran" and then human raised. Acoustic recordings of nasal calls were taken daily and measurements of body mass and neck region were made bi-weekly from May to August and during October 2008. We also dissected the head and neck regions of two 3-4 weeks old male specimens. First inter-sexual differences in fundamental frequency were found at the age of two weeks and of body mass and neck dimensions at the age of 10 weeks. In addition, larynx size diverged well before puberty, i.e. at the age of 24 weeks. In juveniles of both sexes, the mobility of the larynx was limited compared to those of adult males, but nevertheless imposed noticeable effects on formant frequencies of their calls. Supported by RFBR grant 09-04- 00416 (for E.V, I.V., K.E.).
