In this study, we describe the calls emitted by Dendropsophus microps, a species of frog in the family Hylidae, in Serra da Mantiqueira, Campos do Jordão, São Paulo, Brazil, and evaluate their ...functions in the social context using playback experiments. Between October 2016 and November 2017, 15 males of D. microps were recorded. Six hundred and five calls were analyzed and the existence of five types of call compositions was verified: simple call “A normal”; compound call “Af”; shorter “A” call + longer “A” call; “A + Af” calls; and simple call “B”; demonstrating the presence of compound calling in the vocalization structure. One thousand, six hundred and seventeen calls were recorded during the playback experiment in response to the 5 previously constructed stimuli. The “B” call was the most emitted in response to stimuli. The “A”, “Af”, “AA” and “AAf” stimuli caused visual signaling. We recorded a series of 4 to 5 “A” calls during agonistic interactions. Call "B" was identified as an advertisement call and calls "A", "Af", "AA" and "AAf" as aggressive calls. The presence of visual communication in addition to the acoustic communication of these individuals was also observed. The findings increase knowledge of the calling repertoire of this species and can be used in the future in other behavioral and taxonomic studies.
India has been stated to have 10% of the world's total bat's diversity. The present survey was aimed to study the bat species diversity, distribution and activity patterns in north-western Himalayan ...region of India. Field surveys were conducted and echolocation calls were recorded using bat detector, Echometer touch 2 in Shiwalik ranges of Himalaya. The Greater False Vampire Bat (Megaderma lyra) has a broad distribution range that stretches from south to south east Asia. In India the distribution of the species was mostly recorded from southern subtropical coastal regions and north-eastern subtropical moist evergreen forests. In the present study The Greater False Vampire Bat (Megaderma lyra) has been recorded for the first time from Garhwal region of north-western Himalayas. Greater False Vampire Bat (Megaderma lyra) having long forearm (>6.63 ± 0.03cm) and lengthy ear (>3.66 ± 0.08cm), which is a distinguishable feature of the family Megadermatidae. The peak frequency (FMaxE) of echolocation was recorded as 50.295 ± 9.18 kHz. This frequency was initiated at 108.20 ± 2.51 kHz and terminated at 30.76 ± 1.37 kHz. The call structure recorded was very distinguishable and specific to this family.
Stridulation by stridulatory organs has been linked to tarantulas’ (Araneae: Theraphosidae) defence or sexual communication, and the morphology of such organ has been extensively used in tarantula ...systematics. This study was conducted to characterise and compare differences in the acoustic pattern of stridulating sound among seven tarantula species for juveniles and adults of both sexes in Peninsular Malaysia. The species were Psednocnemis jeremyhuffi, P. brachyramosa, Selenocosmia sp. ‘Johor’, Omothymus violaceopes, Cyriopagopus robustus, Chilobrachys sp. ‘Kedah’, and Coremiocnemis sp. ‘Kelantan’. Five provocation methods were used to record the sound which was by tapping the substrate/enclosure, blowing air, waving a pen, poking with blunt object and shaking the enclosure. The stridulating behaviour was assessed using a set of parameters. The result showed that the stridulating behaviour differed between species. Dwarf species like P. jeremyhuffi and P. brachyramosa did not make any audible stridulating sound and preferred to remain motionless. Meanwhile, for the other five species only the large adult females stridulated. Adult males of all species did not make any audible sounds, but rather appeared to be more aggressive and frequently bite. Kruskal-Wallis test showed that intensity, pitch frequency, call duration and pulse duration were significantly different between species. Principal component analaysis (PCA) showed the dissimilarity between the adult females from the five species with Omothymus violaceopes and Chilobrachys sp. ‘Kedah’ the most distinct in terms of call patterns. This study provides evidence on the acoustics pattern of stridulating sound for the tarantulas in Peninsular Malaysia.
Biological sound archives are a major source to investigate geographic variation in animal acoustic signals and their evolutionary drivers. The acoustic signals of anuran species with wide ...distribution ranges often vary geographically as a result of isolation by distance and climate amongst other factors. We examined whether the acoustic structure of call notes would vary geographically in lesser treefrogs Dendropsophus minutus using recordings from bioacoustics repositories. We also tested whether climate (mean annual temperature and annual precipitation) drive geographic variation in those signals. The acoustic distance was unrelated to geographic distance, suggesting that isolation by distance solely cannot explain geographic variation in call structure. Overall, lesser treefrogs uttered call notes with lower frequencies and bandwidths in the west of their range. In addition, frogs produced shorter call notes in hotter, wetter sites and narrow-bandwidth notes in hotter environments. We suggest that frogs produce more calls (not measured here) of shorter durations to maximize transmission and minimize the metabolic costs of calling at high air temperatures. We also suggest that hotter environments favor the propagation of lower-bandwidth calls. This study reinforces the feasibility and power of citizen science and acoustic data repositories for understanding the evolution of anuran acoustic signals.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Male crickets emit acoustic signals (i.e., songs) by chirping using their forewings. Although the mechanisms and adaptive functions of these songs are well studied, knowledge about how songs develop ...within a generation is relatively scarce. Our previous work demonstrated a stable peak frequency at 5.7 kHz in the calling songs recorded from mature adult male crickets (Gryllus bimaculatus). In the present study, we monitored changes in the frequency component over time from the sexual maturity stage (early adult stage). We recorded 300 calling songs from a pool of 122 adults. The peak frequency distribution was lower and unstable (i.e., greater coefficient of variance) in the early adult stage. The mean peak frequency was 4.9 kHz on day 3, but gradually converged to 5.8 kHz over the 2-week adult stage. Immature adult males (emitting immature songs) produced an appropriately tuned song with a peak frequency of 5.8 kHz in an environment of 80% helium and 20% oxygen. These results suggest that the frequency component of the calling song is acquired during the early to mid-adult stage, and may be related to sexual maturation in males. Findings from the helium substitution experiment revealed that physical resistance from surrounding gas molecules negatively affect the stability of male singing, and that muscle development and forewing hardening may contribute to the maturation of singing, suggesting that females may adaptively select sexually mature males based on song traits.
Monitoring threatened species at the individual level is fundamental and crucial in ecology and conservation, especially for critically endangered species. Hainan gibbon (Nomasucs hainanus) is the ...world's rarest primate species with <40 individuals, urgently needs a labor-efficient and continuous individual-level monitoring system to inform science-based conservation actions. Male dispersal, replacement, and formation of new groups with females are crucial for the population dynamics of gibbons. Their loud and elaborate morning songs provide the potential to automate the monitoring of their dynamics. Based on acoustic recordings from focal recording and 13 autonomous recording units within gibbons' home ranges, we developed an automated system, which successively (a) detected song bouts (duration ≈ 10 min, with ≈ 50 phrases) with temporal parameters using an energy detector with a hidden Markov model (F1 score >75 %), (b) detected and classified phrases (duration ≈ 5 s) within song bouts using a random forest model (F1 score ≈ 80–90 %), and (c) classified known individuals by a linear support vector machine (accuracy >93 %), and recognized unknown individuals by Gaussian mixture models (accuracy >90 %). The system successfully monitored a male immigration and kept tracking a dispersing male for nearly a year since it left the natal group to establish its own group with two females. Our system is effective even in the face of an ever-changing population and can be applied to passive acoustic data. It will contribute to the realization of long-term, large-scale, and continuous monitoring of individual dynamics for vocal animals.
•We identified and tracked the dispersal of male Hainan gibbons with an automated system.•The system needs little training data and is robust against data variations.•The system helps to monitor individual dynamics from passive acoustics continuously.
The notion that social complexity may drive communicative complexity has invigorated the research interest in the question of how to assess the structural features of a species' communication system. ...This applies to both the level of the signal repertoire and the level of potential rules governing the succession of elements. This review first provides an overview of some of the most influential studies in the realm of acoustic communication, before turning to a key problem at the foundation of many analyses. Many biological signal repertoires reveal intermediate forms between specific signal types as well as variation within signal types. Therefore, it is often difficult to identify the specific number of signal types (and consequently, their sequential relationships). Nevertheless, subjective classification or ‘hard clustering’ approaches force items into specific categories. Yet, given the graded nature of many repertoires, it may be more appropriate to measure the degree of differentiation within a repertoire, instead of the number of call types, which may also be strongly affected by sampling artefacts. ‘Fuzzy clustering’ provides measures to capture the overall structural variability of a repertoire, i.e. whether they are rather graded or discrete. Because with fuzzy clustering it may also be difficult to identify a single best cluster solution, methods are needed that transcend the number of clusters identified with the cluster analysis. One such approach is the assessment of the distribution of typicality coefficients, which are derived from fuzzy clustering. For the time being, these provide an alternative route to quantitatively test hypotheses regarding the evolution of signal repertoires. Future research should aim to establish a solid mathematical foundation to link the properties of graded repertoires to measures derived from complexity theory. Until then, the notion of complexity to describe the structure of a repertoire should be used with caution.
•Quantitative accounts of signal repertoires are the basis for comparative analyses.•Mammal signal repertoires reveal graded variation within and between call types.•In graded systems, the unambiguous identification of call types is difficult.•Fuzzy clustering estimates the degree of differentiation within a repertoire.•This may allow for novel ways of quantitatively estimating repertoire structure.
 We studied the songs and morphology of the stridulatory file of Isophya modestior across its complete geographic range, in order to test our hypothesis that the male calling song of the species ...shows strong differentiation between the northern (Pannonian) and southern (Balkan) parts of its distribution range, reflecting its disjunct distribution. Our analyses confirm this hypothesis, separating analyzed specimens of I. modestior into two main groups - one present in the central part of the Balkan Peninsula (representing Isophya modestior sensu stricto ), with the second group occurring in the Pannonian Basin, Dinarides, Slovenia and NE Italy. The most reliable difference between the groups is the duration of the main syllable, the number of stridulatory teeth and number of pulses in the main syllable, where all values are higher in specimens from the Balkan Peninsula. Additional analyses showed that within the second group, there are differences in analyzed characters between specimens from the Pannonian Basin and specimens from the Dinaric area, the latter ones having intermediate song characteristics, closer to the group from the Balkan Peninsula. Our study shows that detailed bioacoustic analyses can help to unravel patterns of intraspecific differentiation and thus provide a useful tool for taxonomic studies. Keywords: Balkans, bioacoustics, bush-cricket, oscillogram, Pannonian Basin, stridulatory file
Abstract
The deep learning (DL) revolution is touching all scientific disciplines and corners of our lives as a means of harnessing the power of big data. Marine ecology is no exception. New methods ...provide analysis of data from sensors, cameras, and acoustic recorders, even in real time, in ways that are reproducible and rapid. Off-the-shelf algorithms find, count, and classify species from digital images or video and detect cryptic patterns in noisy data. These endeavours require collaboration across ecological and data science disciplines, which can be challenging to initiate. To promote the use of DL towards ecosystem-based management of the sea, this paper aims to bridge the gap between marine ecologists and computer scientists. We provide insight into popular DL approaches for ecological data analysis, focusing on supervised learning techniques with deep neural networks, and illustrate challenges and opportunities through established and emerging applications of DL to marine ecology. We present case studies on plankton, fish, marine mammals, pollution, and nutrient cycling that involve object detection, classification, tracking, and segmentation of visualized data. We conclude with a broad outlook of the field’s opportunities and challenges, including potential technological advances and issues with managing complex data sets.
High‐throughput environmental sensing technologies are increasingly central to global monitoring of the ecological impacts of human activities. In particular, the recent boom in passive acoustic ...sensors has provided efficient, noninvasive, and taxonomically broad means to study wildlife populations and communities, and monitor their responses to environmental change. However, until recently, technological costs and constraints have largely confined research in passive acoustic monitoring (PAM) to a handful of taxonomic groups (e.g., bats, cetaceans, birds), often in relatively small‐scale, proof‐of‐concept studies.
The arrival of low‐cost, open‐source sensors is now rapidly expanding access to PAM technologies, making it vital to evaluate where these tools can contribute to broader efforts in ecology and biodiversity research. Here, we synthesise and critically assess the current emerging opportunities and challenges for PAM for ecological assessment and monitoring of both species populations and communities.
We show that terrestrial and marine PAM applications are advancing rapidly, facilitated by emerging sensor hardware, the application of machine learning innovations to automated wildlife call identification, and work towards developing acoustic biodiversity indicators. However, the broader scope of PAM research remains constrained by limited availability of reference sound libraries and open‐source audio processing tools, especially for the tropics, and lack of clarity around the accuracy, transferability and limitations of many analytical methods.
In order to improve possibilities for PAM globally, we emphasise the need for collaborative work to develop standardised survey and analysis protocols, publicly archived sound libraries, multiyear audio datasets, and a more robust theoretical and analytical framework for monitoring vocalising animal communities.
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