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Eli Geffen - One of the best experts on this subject based on the ideXlab platform.
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A crescendo in the inner structure of snorts: a reflection of increasing arousal in rock Hyrax songs?
Animal Behaviour, 2020Co-Authors: Yishai A. Weissman, Lee Koren, Vlad Demartsev, Amiyaal Ilany, Adi Barocas, Einat Bar-ziv, Eli GeffenAbstract:Acoustic and rhythmic temporal patterns may have important roles both in animal vocalizations and in human music. Male rock Hyraxes, Procavia capensis, advertise their quality and emotional state by singing a long complex song, comprising repetitive elements. Research has revealed that the temporal structure of Hyrax songs is similar to a musical crescendo, as it includes a gradual increase in amplitude, along with several additional acoustic and structural parameters, throughout the song. In Hyrax songs, the snort is a relatively rare, low and harsh vocal element, which increases in number as the song progresses. We have previously shown that mean snort harshness is positively linked to both the singer's social status and testosterone levels, possibly reflecting inner arousal. Here, we measured the changes in snort harshness and length during natural Hyrax songs. Our results indicate that in mature males, harshness, quantified by shimmer and jitter, increases as the song progresses. We suggest that increasing snort harshness may either (1) indicate the progression of inner excitement or aggression throughout the song or (2) that the harshness may reflect the difficulty of vocal control following increasing effort or the physical fatigue of the vocal cords. In western culture music, such progression is used to increase listener tension and thus retain attention, preventing possible habituation. Thus, understanding the development and progression of challenging elements within animal communication systems may reveal a key fundamental root of modern musical structure, and shed light on the evolutionary basis of musical perception.
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The progression pattern of male Hyrax songs and the role of climactic ending
Scientific Reports, 2017Co-Authors: Vlad Demartsev, Lee Koren, Arik Kershenbaum, Amiyaal Ilany, Yair Geva, Ori Margalit, Inbar Schnitzer, Adi Barocas, Einat Bar-ziv, Eli GeffenAbstract:The study of animal vocal signals can either focus on the properties of distinct vocal elements or address the signal as a whole. Although some attention has been given to the continuous progression patterns of bird songs, such patterns in mammalian vocalisations have been largely overlooked. We examined temporal changes in structural and acoustic parameters in male rock Hyrax songs. We found a gradual increase in call frequency and amplitude towards the song ending, as well as an abrupt increase in bout syntactic complexity, peaking in the last quintile of a song. In musical terms, such a pattern can be described as a crescendo (amplitude increase) with a terminal climax. In Western music, crescendos are used to maintain attention and direct the listeners towards a memorable highpoint of the musical piece. This structure may have an analogous function in animal communication, recruiting audience attention towards the climactic and potentially most informative part of the signal. Our playback experiments revealed that Hyrax males tend to reply more to songs with a climactic ending, indicating that this progression pattern is important for Hyrax communication. We suggest that animal vocal communication research can benefit from adding musical concepts to the analysis toolbox.
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harsh vocal elements affect counter singing dynamics in male rock Hyrax
Behavioral Ecology, 2016Co-Authors: Vlad Demartsev, Lee Koren, Uria Shani, Yael Goll, Eli GeffenAbstract:Morton’s motivation-structural (MS) rules suggest that the acoustic structure of a signal can reflect the caller’s motivation and internal state. In many species, low-frequency and noisy (harsh) sounds have been found to comply with MS rules, accompanying agonistic interactions and functioning as a badge of aggression and dominance. Male rock Hyraxes (Procavia capensis) often produce long and complex advertisement calls (songs) both "spontaneously" and in counter-singing sessions with other males. Hyrax songs include a "snort" vocal element, which is a harsh sound produced only by mature, dominant males. We predicted that the number of snort elements in the song would affect the dynamics of male Hyrax counter-singing. We performed 3 series of playback experiments of natural and artificially manipulated songs on a wild Hyrax population. We found that the probability of initiating counter-singing by nearby males increased together with the number of snorts in the stimulus song. Furthermore, the receivers replied to the synthetic "snort-only" vocal sequences at an equal rate as to their origin song as long as the snort elements maintained their original position within the signal. Our findings suggest that the snort component is one of the main information transfer channels in male Hyrax singing and can elicit conspecific singing even when isolated from other vocal elements. In addition, the position of snort elements (their temporal pattern and rhythm) bears a possible significance in keeping the overall signal meaningful. Finally, our findings support previous claims that harsh sounds constitute one of the key components in vocal communication.
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syntactic structure and geographical dialects in the songs of male rock Hyraxes
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: Arik Kershenbaum, Leon Blaustein, Amiyaal Ilany, Eli GeffenAbstract:Few mammalian species produce vocalizations that are as richly structured as bird songs, and this greatly restricts the capacity for information transfer. Syntactically complex mammalian vocalizations have been previously studied only in primates, cetaceans and bats. We provide evidence of complex syntactic vocalizations in a small social mammal: the rock Hyrax (Procavia capensis: Hyracoidea). We adopted three algorithms, commonly used in genetic sequence analysis and information theory, to examine the order of syllables in Hyrax calls. Syntactic dialects exist, and the syntax of Hyrax calls is significantly different between different regions in Israel. Call syntax difference is positively correlated to geographical distance over short distances. No correlation is found over long distances, which may reflect limited dispersal movement. These findings indicate that rich syntactic structure is more common in the vocalizations of mammalian taxa than previously thought and suggest the possibility of vocal production learning in the Hyrax.
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individual identity is communicated through multiple pathways in male rock Hyrax procavia capensis songs
Behavioral Ecology and Sociobiology, 2011Co-Authors: Lee Koren, Eli GeffenAbstract:Communicating individual identity is essential for stable social systems. It is assumed that there are benefits for both senders and receivers to provide and discriminate identity cues. In this study, we investigate the possible routes senders use to acoustically broadcast their individual identity. Using discriminant function analysis of temporal and spectral acoustic measurements and analysis of song-element order, we explore the means male rock Hyrax (Procavia capensis) singers utilize vocalization to express individual identity. Despite the fact that males use only three song elements, the pattern of acoustic characteristics, their temporal and frequency attributes vary according to the identity of singer. We show that in Hyrax, individuality is expressed by highly variable, complex signals that are not condition dependent and are stable over years in singers that did not alter their spatial position. We also show that individuality signals are not linked to relatedness or to geographic location. The ability to discriminate individuals from vocal signatures needs to be further tested using controlled playback experiments.
Paul R Manger - One of the best experts on this subject based on the ideXlab platform.
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nuclear organization of the rock Hyrax procavia capensis amygdaloid complex
Brain Structure & Function, 2016Co-Authors: Audemarie Limacherburrell, Nadine Gravett, Busisiwe C Maseko, Adhil Bhagwandin, Paul R MangerAbstract:The current study details the nuclear organization of the rock Hyrax amygdaloid complex using both Nissl and myelin stains, along with a range of immunohistochemical stains. The rock Hyrax appears to be the least derived of the Afrotherians, a group with a huge range of body phenotypes, life histories and specialized behaviours, brain sizes, and ecological niches. In this sense, the rock Hyrax represents a species where the organization of the amygdaloid complex may be reflective of that in stem Eutherian mammals. Our analysis indicates that the nuclear organization of the rock Hyrax amygdaloid complex is indeed very similar to that in other mammals studied, with four major nuclear groupings (the deep or basolateral group; the superficial or cortical-like or corticomedial group; the centromedial group; and the other amygdaloid nuclei) being observed, which is typical of Eutherian mammals. Moreover, each of these groupings is composed of several nuclei, the vast majority of which were readily identified in the rock Hyrax. Small nuclei identified in rodents and primates were absent in the superficial and centromedial groups, seemingly involved with olfaction. A novel shell-like nucleus of the accessory basal nuclear cluster was observed in the rock Hyrax, again, likely to be involved in olfaction. The current study underlines the conserved nature of nuclear parcellation in the Eutherian mammal amygdaloid complex and indicates that across most species, the flow of information processing related to species-specific affective-laden stimuli and the resultant physiological and behavioural outcomes are likely to be similar across species.
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sleep in the rock Hyrax procavia capensis
Brain Behavior and Evolution, 2012Co-Authors: Nadine Gravett, Oleg I Lyamin, Adhil Bhagwandin, Jerome M Siegel, Paul R MangerAbstract:We investigated sleep in therock Hyrax, Procavia capensis, a social mammal that typically lives in colonies on rocky outcrops throughout most parts of Southern Africa. The sleep of 5 wild-captured, adult rock Hyraxes was recorded continuously for 72 h using telemetric relay of signals and allowing unimpeded movement. In addition to waking, slow wave sleep (SWS) and an unambiguous rapid eye movement (REM) state, a sleep state termed somnus innominatus (SI), characterized by low-voltage, high-frequency electroencephalogram, an electromyogram that stayed at the same amplitude as the preceding SWS episode and a mostly regular heart rate, were identified. If SI can be considered a form of low-voltage non-REM, the implication would be that the rock Hyrax exhibits the lowest amount of REM recorded for any terrestrial mammal studied to date. Conversely, if SI is a form of REM sleep, it would lead to the classification of a novel subdivision of this state; however, further investigation would be required. The Hyraxes spent on average 15.89 h (66.2%) of the time awake, 6.02 h (25.1%) in SWS, 43 min (3%) in SI and 6 min (0.4%) in REM. The unambiguous REM sleep amounts were on average less than 6 min/day. The most common state transition pathway in these animals was found to be wake → SWS → wake. No significant differences were noted with regard to total sleep time, number of episodes and episode duration for all states between the light and dark periods.Thus, prior classification of the rock Hyrax as strongly diurnal does not appear to hold under controlled laboratory conditions.
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neocortical neuron morphology in afrotheria comparing the rock Hyrax with the african elephant
Annals of the New York Academy of Sciences, 2011Co-Authors: Serena Bianchi, Amy L Bauernfeind, Cheryl D Stimpson, Muhammad A Spocter, Kanika Gupta, Christopher J Bonar, Bob Jacobs, Paul R Manger, Chet C SherwoodAbstract:The mammalian neocortex contains a great variety of neuronal types. In particular, recent studies have shown substantial morphological diversity among spiny projecting neurons in species that diverged close to the base of the mammalian radiation (e.g., monotremes, afrotherians, and xenarthrans). Here, we used a Golgi technique to examine different neuronal morphologies in an afrotherian species, the rock Hyrax (Procavia capensis), and provide a comparison with the related African elephant (Loxodonta africana). Results showed that spiny neurons in the rock Hyrax neocortex exhibit less morphological variation than in elephants, displaying a higher frequency of relatively “typical” pyramidal neurons. A quantitative comparison of rock Hyrax pyramidal neuron morphology between frontal and visual areas, moreover, revealed greater spine density of neurons in frontal cortex, but no differences in other morphological aspects. Regional variations in pyramidal structure have also been observed in the African elephant, as well as a number of primate species.
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distribution of orexin a immunoreactive neurons and their terminal networks in the brain of the rock Hyrax procavia capensis
Journal of Chemical Neuroanatomy, 2011Co-Authors: Nadine Gravett, Adhil Bhagwandin, Kjell Fuxe, Paul R MangerAbstract:The present study describes the distribution of orexin-A immunoreactive neurons and terminal networks in relation to the previously described catecholaminergic, cholinergic and serotonergic systems within the brain of the rock Hyrax, Procavia capensis. Adult female rock Hyrax brains were sectioned and immunohistochemically stained with an antibody to orexin-A. The staining revealed that the neurons were mainly located within the hypothalamus as with other mammals. The orexinergic terminal network distribution also resembled the typical mammalian plan. High-density orexinergic terminal networks were located within regions of the diencephalon (e.g. paraventricular nuclei), midbrain (e.g. serotonergic nuclei) and pons (locus coeruleus), while medium density orexinergic terminal networks were evident in the telencephalic (e.g. basal forebrain), diencephalic (e.g. hypothalamus), midbrain (e.g. periaqueductal gray matter), pontine (e.g. serotonergic nuclei) and medullary regions (e.g. serotonergic and catecholaminergic nuclei). Although the distribution of the orexinergic terminal networks was typically mammalian, the rock Hyrax did show one atypical feature, the presence of a high-density orexinergic terminal network within the anterodorsal nucleus of the dorsal thalamus (AD). The dense orexinergic innervation of the AD nucleus has only been reported previously in the Nile grass rat, Arvicanthis niloticus and Syrian hamster, Mesocricetus auratus, both diurnal mammals. It is possible that orexinergic innervation of the AD nucleus might be a unique feature associated with diurnal mammals. It was also noted that the dense orexinergic innervation of the AD nucleus coincided with previously identified cholinergic neurons and terminal networks in this particular nucleus of the rock Hyrax brain. It is possible that this dense orexinergic innervation of the AD nucleus in the brain of the rock Hyrax may act in concert with the cholinergic neurons and/or the cholinergic axonal terminals, which in turn may influence arousal states and motivational processing.
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Nuclear organization of cholinergic, putative catecholaminergic and serotonergic nuclei in the brain of the eastern rock elephant shrew, Elephantulus myurus
Journal of Chemical Neuroanatomy, 2010Co-Authors: Raymond P. Pieters, Nadine Gravett, Kjell Fuxe, Paul R MangerAbstract:The organization of the nuclear subdivisions of the cholinergic, putative catecholaminergic and serotonergic systems of the brain of the elephant shrew (Elephantulus myurus) were determined following immunohistochemistry for choline acetyltransferase, tyrosine hydroxylase and serotonin, respectively. This was done in order to determine if differences in the nuclear organization of these systems in comparison to other mammals were evident and how any noted differences may relate to specialized behaviours of the elephant shrew. The elephant shrew belongs to the order Macroscelidea, and forms part of the Afrotherian mammalian cohort. In general, the organization of the nuclei of these systems resembled that described in other mammalian species. The cholinergic system showed many features in common with that seen in the rock Hyrax, rodents and primates; however, specific differences include: (1) cholinergic neurons were observed in the superior and inferior colliculi, as well as the cochlear nuclei; (2) cholinergic neurons were not observed in the anterior nuclei of the dorsal thalamus as seen in the rock Hyrax; and (3) cholinergic parvocellular nerve cells forming subdivisions of the laterodorsal and pedunculopontine tegmental nuclei were not observed at the midbrain/pons interface as seen in the rock Hyrax. The organization of the putative catecholaminergic system was very similar to that seen in the rock Hyrax and rodents except for the lack of the rodent specific C3 nucleus, the dorsal division of the anterior hypothalamic group (A15d) and the compact division of the locus coeruleus (A6c). The nuclear organization of the serotonergic system was identical to that seen in all eutherian mammals studied to date. The additional cholinergic neurons found in the cochlear nucleus and colliculi may relate to a specific acoustic signalling system observed in elephant shrews expressed when the animals are under stress or detect a predator. These neurons may then function to increase attention to this type of acoustic signal termed foot drumming.
Colleen T. Downs - One of the best experts on this subject based on the ideXlab platform.
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no effects of huddling on core body temperature in rock Hyrax procavia capensis
African Zoology, 2013Co-Authors: Colleen T. Downs, Kirsten Wimberger, Amyleigh WilsonAbstract:Huddling is a behavioural energy conservation mechanism that is widely used by many small endotherms at low ambient temperatures. Huddling has many benefits, including decreasing the metabolic cost of maintaining body temperature (Tb), reducing the amount of heat lost to the environment, and increasing the local temperature of the nest. To test the effects of huddling on Tb, 10 rock Hyrax, Procavia capensis, were housed in outside cages in four groups, varying from one to four individuals. iButtons® were surgically implanted into each rock Hyrax to record their Tb every 15 min from August to November. Despite considerable variations in ambient temperatures, the rock Hyrax were found to display some degree of heterothermy by varying their mean Tb from 36.70 to 37.72°C (n = 10) but not allowing it to drop below 33.60°C or rise above 39.67°C. Contrary to what was predicted, rock Hyrax did not display any significant effects of huddling on Tb, irrespective of group size.
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seasonal patterns in body temperature of free living rock Hyrax procavia capensis
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2006Co-Authors: Kelly J Brown, Colleen T. DownsAbstract:Rock Hyrax (Procavia capensis) are faced with large daily fluctuations in ambient temperature during summer and winter. In this study, peritoneal body temperature of free-living rock Hyrax was investigated. During winter, when low ambient temperatures and food supply prevail, rock Hyrax maintained a lower core body temperature relative to summer. In winter body temperatures during the day were more variable than at night. This daytime variability is likely a result of body temperatures being raised from basking in the sun. Body temperatures recorded during winter never fell to low levels recorded in previous laboratory studies. During summer ambient temperatures exceeded the thermoneutral zone of the rock Hyrax throughout most of the day, while crevice temperatures remained within the thermoneutral zone of rock Hyrax. However, in summer variation in core body temperature was small. Minimum and maximum body temperatures did not coincide with minimum and maximum ambient temperatures. Constant body temperatures were also recorded when ambient temperatures reached lethal limits. During summer it is likely that rock Hyrax select cooler refugia to escape lethal temperatures and to prevent excessive water loss. Body temperature of rock Hyrax recorded in this study reflects the adaptability of this animal to the wide range of ambient temperatures experienced in its natural environment.
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seasonal behavioural patterns of free living rock Hyrax procavia capensis
Journal of Zoology, 2005Co-Authors: Kelly J Brown, Colleen T. DownsAbstract:The behavioural use of rock crevices by rock HyraxProcaviacapensis was essential in avoiding harsh environmental conditions during summer. Foraging was the most dominant above-ground behaviour exhibited by rock Hyrax during summer. Most ambient temperatures in the early morning of summer fell within the rock Hyrax thermoneutral zone, which enabled the animals to forage without the need for prior heating from a solar energy source. Basking was an essential behaviour displayed by rock Hyrax in winter. The low quality and scarce food source may be inadequate to meet the metabolic requirements of rock Hyrax at low ambient temperatures. It therefore seems that basking is not only an energy conservation mechanism but also essential for the survival of rock Hyrax during winter. Juvenile rock Hyrax have a higher surface area to volume ratio and are more vulnerable to low ambient conditions than adults. As a result they displayed a different behaviour pattern to adult rock Hyrax during winter. Juveniles required larger amounts of food to meet their energetic requirements, while adults spent greater amounts of time basking. The extent to which rock Hyrax meet energetic requirements depends on the interaction of ambient temperature, food availability, food quality and foraging efficiency in the presence of predators. The extent to which each of these factors influenced behaviour differed on a daily and seasonal basis.
Kelly J Brown - One of the best experts on this subject based on the ideXlab platform.
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seasonal patterns in body temperature of free living rock Hyrax procavia capensis
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2006Co-Authors: Kelly J Brown, Colleen T. DownsAbstract:Rock Hyrax (Procavia capensis) are faced with large daily fluctuations in ambient temperature during summer and winter. In this study, peritoneal body temperature of free-living rock Hyrax was investigated. During winter, when low ambient temperatures and food supply prevail, rock Hyrax maintained a lower core body temperature relative to summer. In winter body temperatures during the day were more variable than at night. This daytime variability is likely a result of body temperatures being raised from basking in the sun. Body temperatures recorded during winter never fell to low levels recorded in previous laboratory studies. During summer ambient temperatures exceeded the thermoneutral zone of the rock Hyrax throughout most of the day, while crevice temperatures remained within the thermoneutral zone of rock Hyrax. However, in summer variation in core body temperature was small. Minimum and maximum body temperatures did not coincide with minimum and maximum ambient temperatures. Constant body temperatures were also recorded when ambient temperatures reached lethal limits. During summer it is likely that rock Hyrax select cooler refugia to escape lethal temperatures and to prevent excessive water loss. Body temperature of rock Hyrax recorded in this study reflects the adaptability of this animal to the wide range of ambient temperatures experienced in its natural environment.
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seasonal behavioural patterns of free living rock Hyrax procavia capensis
Journal of Zoology, 2005Co-Authors: Kelly J Brown, Colleen T. DownsAbstract:The behavioural use of rock crevices by rock HyraxProcaviacapensis was essential in avoiding harsh environmental conditions during summer. Foraging was the most dominant above-ground behaviour exhibited by rock Hyrax during summer. Most ambient temperatures in the early morning of summer fell within the rock Hyrax thermoneutral zone, which enabled the animals to forage without the need for prior heating from a solar energy source. Basking was an essential behaviour displayed by rock Hyrax in winter. The low quality and scarce food source may be inadequate to meet the metabolic requirements of rock Hyrax at low ambient temperatures. It therefore seems that basking is not only an energy conservation mechanism but also essential for the survival of rock Hyrax during winter. Juvenile rock Hyrax have a higher surface area to volume ratio and are more vulnerable to low ambient conditions than adults. As a result they displayed a different behaviour pattern to adult rock Hyrax during winter. Juveniles required larger amounts of food to meet their energetic requirements, while adults spent greater amounts of time basking. The extent to which rock Hyrax meet energetic requirements depends on the interaction of ambient temperature, food availability, food quality and foraging efficiency in the presence of predators. The extent to which each of these factors influenced behaviour differed on a daily and seasonal basis.
Lee Koren - One of the best experts on this subject based on the ideXlab platform.
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A crescendo in the inner structure of snorts: a reflection of increasing arousal in rock Hyrax songs?
Animal Behaviour, 2020Co-Authors: Yishai A. Weissman, Lee Koren, Vlad Demartsev, Amiyaal Ilany, Adi Barocas, Einat Bar-ziv, Eli GeffenAbstract:Acoustic and rhythmic temporal patterns may have important roles both in animal vocalizations and in human music. Male rock Hyraxes, Procavia capensis, advertise their quality and emotional state by singing a long complex song, comprising repetitive elements. Research has revealed that the temporal structure of Hyrax songs is similar to a musical crescendo, as it includes a gradual increase in amplitude, along with several additional acoustic and structural parameters, throughout the song. In Hyrax songs, the snort is a relatively rare, low and harsh vocal element, which increases in number as the song progresses. We have previously shown that mean snort harshness is positively linked to both the singer's social status and testosterone levels, possibly reflecting inner arousal. Here, we measured the changes in snort harshness and length during natural Hyrax songs. Our results indicate that in mature males, harshness, quantified by shimmer and jitter, increases as the song progresses. We suggest that increasing snort harshness may either (1) indicate the progression of inner excitement or aggression throughout the song or (2) that the harshness may reflect the difficulty of vocal control following increasing effort or the physical fatigue of the vocal cords. In western culture music, such progression is used to increase listener tension and thus retain attention, preventing possible habituation. Thus, understanding the development and progression of challenging elements within animal communication systems may reveal a key fundamental root of modern musical structure, and shed light on the evolutionary basis of musical perception.
-
The progression pattern of male Hyrax songs and the role of climactic ending
Scientific Reports, 2017Co-Authors: Vlad Demartsev, Lee Koren, Arik Kershenbaum, Amiyaal Ilany, Yair Geva, Ori Margalit, Inbar Schnitzer, Adi Barocas, Einat Bar-ziv, Eli GeffenAbstract:The study of animal vocal signals can either focus on the properties of distinct vocal elements or address the signal as a whole. Although some attention has been given to the continuous progression patterns of bird songs, such patterns in mammalian vocalisations have been largely overlooked. We examined temporal changes in structural and acoustic parameters in male rock Hyrax songs. We found a gradual increase in call frequency and amplitude towards the song ending, as well as an abrupt increase in bout syntactic complexity, peaking in the last quintile of a song. In musical terms, such a pattern can be described as a crescendo (amplitude increase) with a terminal climax. In Western music, crescendos are used to maintain attention and direct the listeners towards a memorable highpoint of the musical piece. This structure may have an analogous function in animal communication, recruiting audience attention towards the climactic and potentially most informative part of the signal. Our playback experiments revealed that Hyrax males tend to reply more to songs with a climactic ending, indicating that this progression pattern is important for Hyrax communication. We suggest that animal vocal communication research can benefit from adding musical concepts to the analysis toolbox.
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harsh vocal elements affect counter singing dynamics in male rock Hyrax
Behavioral Ecology, 2016Co-Authors: Vlad Demartsev, Lee Koren, Uria Shani, Yael Goll, Eli GeffenAbstract:Morton’s motivation-structural (MS) rules suggest that the acoustic structure of a signal can reflect the caller’s motivation and internal state. In many species, low-frequency and noisy (harsh) sounds have been found to comply with MS rules, accompanying agonistic interactions and functioning as a badge of aggression and dominance. Male rock Hyraxes (Procavia capensis) often produce long and complex advertisement calls (songs) both "spontaneously" and in counter-singing sessions with other males. Hyrax songs include a "snort" vocal element, which is a harsh sound produced only by mature, dominant males. We predicted that the number of snort elements in the song would affect the dynamics of male Hyrax counter-singing. We performed 3 series of playback experiments of natural and artificially manipulated songs on a wild Hyrax population. We found that the probability of initiating counter-singing by nearby males increased together with the number of snorts in the stimulus song. Furthermore, the receivers replied to the synthetic "snort-only" vocal sequences at an equal rate as to their origin song as long as the snort elements maintained their original position within the signal. Our findings suggest that the snort component is one of the main information transfer channels in male Hyrax singing and can elicit conspecific singing even when isolated from other vocal elements. In addition, the position of snort elements (their temporal pattern and rhythm) bears a possible significance in keeping the overall signal meaningful. Finally, our findings support previous claims that harsh sounds constitute one of the key components in vocal communication.
-
individual identity is communicated through multiple pathways in male rock Hyrax procavia capensis songs
Behavioral Ecology and Sociobiology, 2011Co-Authors: Lee Koren, Eli GeffenAbstract:Communicating individual identity is essential for stable social systems. It is assumed that there are benefits for both senders and receivers to provide and discriminate identity cues. In this study, we investigate the possible routes senders use to acoustically broadcast their individual identity. Using discriminant function analysis of temporal and spectral acoustic measurements and analysis of song-element order, we explore the means male rock Hyrax (Procavia capensis) singers utilize vocalization to express individual identity. Despite the fact that males use only three song elements, the pattern of acoustic characteristics, their temporal and frequency attributes vary according to the identity of singer. We show that in Hyrax, individuality is expressed by highly variable, complex signals that are not condition dependent and are stable over years in singers that did not alter their spatial position. We also show that individuality signals are not linked to relatedness or to geographic location. The ability to discriminate individuals from vocal signatures needs to be further tested using controlled playback experiments.
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elevated testosterone levels and social ranks in female rock Hyrax
Hormones and Behavior, 2006Co-Authors: Lee Koren, Ofer Mokady, Eli GeffenAbstract:In mammals, males maintain significantly higher testosterone (T, ‘the male hormone’) levels than females throughout the year and are typically dominant over females. Our study of the cooperatively breeding rock Hyrax (Procavia capensis) demonstrated a distinct exception. In most Hyrax social groups that we studied, adult females were at the highest social rank within the group and showed higher than or equal T levels to males. To our knowledge, this is the first reported instance of adult female mammals demonstrating higher T levels than adult males. However, although T levels significantly correlated with rank in males, in females such correlations were not detected, suggesting a more complex interplay between behavior and endocrine factors in this species.