Angela S. Stoeger

University of Vienna | UniWien · Department of Cognitive Biology

In the last decade clear evidence has accumulated that elephants are capable of vocal production learning. Examples of vocal imitation are documented in African (Loxodonta africana) and Asian (Elephas maximus) elephants, but little is known about the function of vocal learning within the natural communication systems of either species. We are also...

Vocal imitation has convergently evolved in many species, allowing learning and cultural transmission of complex, conspecific sounds, as in birdsong [1, 2]. Scattered instances also exist of vocal imitation across species, including mockingbirds imitating other species or parrots and mynahs producing human speech [3, 4]. Here, we document a male As...

Gaining information about conspecifics via long-distance vocalizations is crucial for social and spatially flexible species such as the African elephant (Loxodonta africana). Female elephants are known to discriminate individuals and kin based on acoustic cues. Specifically, females approached the loudspeaker exclusively with playbacks of familiar...

Recent comparative data reveal that formant frequencies are cues to body size in animals, due to a close relationship between formant frequency spacing, vocal tract length and overall body size. Accordingly, intriguing morphological adaptations to elongate the vocal tract in order to lower formants occur in several species, with the size exaggerati...

Until recently, the prevailing theory about male African elephants (Loxodonta africana) was that, once adult and sexually mature, males are solitary and targeted only at finding estrous females. While this is true during the state of ‘musth’ (a condition characterized by aggressive behavior and elevated androgen levels), ‘non-musth’ males exhibit a...

Many species communicate by combining signals into multimodal combinations. Elephants live in multi-level societies where individuals regularly separate and reunite. Upon reunion, elephants often engage in elaborate greeting rituals, where they use vocalisations and body acts produced with different body parts and of various sensory modalities (e.g...

This chapter describes the effects of noise on animals in terrestrial and aquatic habitats. Potential adverse effects cover a range of behavioral changes and physiological responses, including—in extreme cases—physical injury and death. The types and severity of effects are related to a number of noise features, including the received noise level a...

Sound production mechanisms set the parameter space available for transmitting biologically relevant information in vocal signals. Low–frequency rumbles play a crucial role in coordinating social interactions in elephants’ complex fission–fusion societies. By emitting rumbles through either the oral or the three-times longer nasal vocal tract, Afri...

Vocal production learning is the ability to modify a vocal output in response to auditory experience. It is essential for human speech production and language acquisition. Vocal learning evolved independently several times in vertebrates, indicating evolutionary pressure in favor of this trait. This enables cross-species comparative analysis to be...

Most studies on elephant vocal communication have focused on the low-frequency rumble, with less effort on other vocalization types such as the most characteristic elephant call, the trumpet. Yet, a better and more complete understanding of the elephant vocal system requires investigating other vocalization types and their functioning in more detai...

Elephants exhibit remarkable vocal plasticity, and case studies reveal that individuals of African savannah ( Loxodonta africana ) and Asian ( Elephas maximus ) elephants are capable of vocal production learning. Surprisingly, however, little is known about contextual learning (usage and comprehension learning) in elephant communication. Usage lear...

How do elephants achieve their enormous vocal flexibility when communicating, imitating or creating idiosyncratic sounds? The mechanisms that underpin this trait combine motoric abilities with vocal learning processes. We demonstrate the unusual production techniques used by five African savanna elephants to create idiosyncratic sounds, which they...

Background Anatomical and cognitive adaptations to overcome morpho-mechanical limitations of laryngeal sound production, where body size and the related vocal apparatus dimensions determine the fundamental frequency, increase vocal diversity across taxa. Elephants flexibly use laryngeal and trunk-based vocalizations to form a repertoire ranging fro...

Most aquatic mammals have complex social and communication systems. Interestingly, little is known about otters’ vocal communication compared to other aquatic mammals. Here, for the first time, we acoustically describe vocalizations of the neotropical otter (Lontra longicaudis), a solitary and endangered New World otter species. We recorded vocaliz...

The recent elephant species, the African savannah, the African forest, and the Asian elephant, are all social, and intraspecific communication is highly developed. Specifically, acoustic signals play a fundamental role within elephant societies. In this chapter, I have provided an overview of elephant communication with an emphasis on the African s...

Understanding why related species combine calls in different ways could provide insight into the selection pressures on the evolution of combinatorial communication. African savannah elephants (Loxodonta africana), African forest elephants (Loxodonta cyclotis), and Asian elephants (Elephas maximus) all combine broadband calls (roars, barks, and cri...

African savanna elephants live in dynamic fission⁻fusion societies and exhibit a sophisticated vocal communication system. Their most frequent call-type is the 'rumble', with a fundamental frequency (which refers to the lowest vocal fold vibration rate when producing a vocalization) near or in the infrasonic range. Rumbles are used in a wide variet...

This corrects the article DOI: 10.1038/srep46414.

This study used the source and filter theory approach to analyse sex differences in the acoustic features of African elephant (Loxodonta africana) low-frequency rumbles produced in social contexts (‘social rumbles’). Permuted discriminant function analysis revealed that rumbles contain sufficient acoustic information to predict the sex of a vocaliz...

This study used the source and filter theory approach to analyse sex differences in the acoustic features of African elephant (Loxodonta africana) low-frequency rumbles produced in social contexts (‘social rumbles’). Permuted discriminant function analysis revealed that rumbles contain sufficient acoustic information to predict the sex of a vocaliz...

Male African elephant rumbling while being approached. (MP4)

Male African elephant rumbling in a spatial separation situation. (MP4)

Male African elephant rumbling during browsing and feeding activity. (MP4)

Extracted factors of the principal component analysis. (DOCX)

Sound sample of a low-arousal social rumble of each sex, with the female rumbling first. Maximum frequency of the sound file was set to 200 Hz and the absolute peak of the amplitude was scaled to 0.99. (WAV)

Description of the source- and filter-related parameters measured. (DOCX)

Age classification. (DOCX)

Extracted factors of the principal component analysis. (DOCX)

Dataset. (XLSX)

Shoulder height classification. (DOCX)

Trumpet calls are very loud voiced signals given by highly aroused elephants, and appear to be produced by a forceful expulsion of air through the trunk. Beyond their characteristic “brassy quality” previously attributed to shockwave formation, some trumpet calls are also characterized by stepwise fundamental frequency increase and decrease. Here w...

Research on the evolution of human speech and music benefits from hypotheses and data generated in a number of disciplines. The purpose of this article is to illustrate the high relevance of pinniped research for the study of speech, musical rhythm, and their origins, bridging and complementing current research on primates and birds. We briefly dis...

Infrasonic and seismic communication in terrestrial vertebrates is generally poorly known. Moreover, studies of these communication modalities have been restricted to relatively few vertebrate groups. In this chapter we begin with the non-Afrotherian vertebrates and review what is known about their infrasonic (including birds and mammals) and seism...

The decline of habitat for elephants due to expanding human activity is a serious conservation problem. This has continuously escalated the human-elephant conflict in Africa and Asia. Elephants make extensive use of powerful infrasonic calls (rumbles) that travel distances of up to several kilometers. This makes elephants well-suited for acoustic m...

Background: Recent research reveals that giraffes (Giraffa camelopardalis sp.) exhibit a socially structured, fission– fusion system. In other species possessing this kind of society, information exchange is important and vocal com- munication is usually well developed. But is this true for giraffes? Giraffes are known to produce sounds, but there...

The human – elephant conflict is one of the most serious conservation problems in Asia and Africa today. The involuntary confrontation of humans and elephants claims the lives of many animals and humans every year. A promising approach to alleviate this conflict is the development of an acoustic early warning system. Such a system requires the robu...

We used vocal indicators to examine the effect of a translocation of an African elephant family herd within the Kruger National Park. These animals were moved 300 km from their home range, but returned unaided to this range within 23 days. We found that translocation resulted in a change in the mean fundamental frequency of low-frequency elephant v...

Animal vocal signals are increasingly used to monitor wildlife populations and to obtain estimates of species occurrence and abundance. In future, acoustic monitoring should function not only to detect animals, but also to extract detailed information about populations by discriminating sexes, age groups, social or kin groups, and potentially indiv...

Although living in substantially different habitats, African ( Loxodonta sp . ) and Asian ( Elephas maximus ) elephants are extremely social and intra-specifi c communication is therefore highly developed in these species. In particular, elephants are very vocal and acoustic signals play an integral part within the society of African and Asian elep...

Elephants' low-frequency vocalizations are produced by flow-induced self-sustaining oscillations of laryngeal tissue. To date, little is known in detail about the vibratory phenomena in the elephant larynx. Here, we provide a first descriptive report of the complex oscillatory features found in the excised larynx of a 25 year old female African ele...

The automated acoustic detection of elephants is an impor-tant factor in alleviating the human-elephant conflict in Asia and Africa. In this paper, we present a method for the au-tomated detection of elephant presence and evaluate it on a large dataset of wildlife recordings. We introduce a novel technique for signal enhancement to improve the robu...

Infant giant pandas (Ailuropoda melanoleuca) are highly vocal during the first few weeks of their life. Despite this, no previous studies have attempted to systematically categorize infant giant panda vocalizations into different call types. In this study, we used acoustic and video analyses to split infant giant panda vocalizations into three dist...

The following vocal interaction with the trainer is documented: Koshik: “choah” (good) Trainer: “choah choah annyong” (good good hello) Koshik: “choah” (good) Trainer: “choah choah annyong” (good good hello) Koshik: “choah” (good) Trainer: “choah choah” (good good) Koshik: “choah” (good) Trainer: “annyong” (hello) Koshik: “choah” (good) Trainer: “a...

Sampling frequency 44.100 Hz.

Sampling frequency 44.100 Hz.

Sampling frequency 44.100 Hz.

Sampling frequency 44.100 Hz.

Recent comparative data reveal that formant frequencies are cues to body size in animals, due to a close relationship between formant frequency spacing, vocal tract length and overall body size. Accordingly, intriguing morphological adaptations to elongate the vocal tract in order to lower formants occur in several species, with the size exaggerati...

Oral rumble-5 fps-slow-mo: Sound visualization of an oral rumble in slow motion. This movie shows the sound emission during an oral rumble in slow motion (5 frames per second). (AVI)

Spectrograms and power spectra presenting two examples of rumbling vocalizations from a 29 year old female African elephant (Drumbo) recorded at the Vienna Zoo in 2003. Recordings were captured with a condenser microphone AKG 480 B CK 62 and a DA-P1 DAT recorder. Figures A and B show a rumble recorded during spatial separation from a part of the gr...

Spectrograms and power spectra to show examples of rumbles from a 43 year old female African elephant (Jumbo) recorded at the Vienna Zoo in 2003 (using the same equipment as described in Figure S1). Figures A and B also show a rumble recorded during spatial separation from the group, again with the formant structure of a typical nasal rumble. Figur...

Nasal rumble-25 fps-sound: Sound visualization of a nasal rumble. This movie shows the sound emission during a nasal rumble. (AVI)

Oral rumble-25 fps-sound: Sound visualization of an oral rumble. This movie shows the sound emission during an oral rumble. (AVI)

Nasal rumble-5 fps-slow-mo: Sound visualization of a nasal rumble in slow motion. This movie shows the sound emission during a nasal rumble in slow motion (5 frames per second). (AVI)

Infant giant pandas are highly vocal during the first few weeks of life, producing vocalisations that are characterised by noisy, aperiodic segments. The aperiodic character of many animal vocalisations results from irregular vibratory regimes of the vocal folds, and one proposed function of this so‐called nonlinear phenomena (NLP) in animal vocali...

The Song of the Elephant In mammals, vocal sound production generally occurs in one of two ways, either through muscular control—as when a cat purrs or, more commonly, by air passing through the vocal folds—which occurs in humans and facilitates production of extremely high frequency bat calls. Over the past 20 years, it has been recognized that el...

The present study describes the acoustic structure and associated behavioural contexts of vocalizations of Asian elephant calves. Three hundred twenty-seven vocalizations of six calves aged between 6 and 27 months were recorded at the Emmen and the Cologne zoo. Based on temporal and structural characteristics including nonlinear phenomena, we struc...

Arousal-based physiological changes influence acoustic features of vocalizations in mammals. In particular, nonlinear phenomena are thought to convey information about the caller's arousal state. This hypothesis was tested in the infant African elephant (Loxodonta africana) roar, a call type produced in situations of arousal and distress. Ninety-tw...

African savannah elephants (Loxodonta africana) have a complex acoustic communication system, but very little is known about their vocal ontogeny. A first approach in ontogenetic studies is to define the call repertoire of specific age groups. Twelve hundred calls of 11 infant elephants from neonatal to 18 months of age recorded at the Vienna Zoo i...

There are a few mammalian species that can modify their vocalizations in response to auditory experience. We describe two examples of vocal imitation by African Savannah Elephants (Loxodonta africana), a terrestrial mammal that lives in a multitiered fission-fusion society. The first case of vocal imitation involves Mlaika, an adolescent female Afr...

There are a few mammalian species that can modify their vocalizations in response to auditory experience--for example, some marine mammals use vocal imitation for reproductive advertisement, as birds sometimes do. Here we describe two examples of vocal imitation by African savannah elephants, Loxodonta africana, a terrestrial mammal that lives in a...