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Vocalizations of Red Wolves (Canis rufus)

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Abstract

Elicited and spontaneous vocalizations of wild canids in southeastern Texas and southwestern Louisiana were studied from December 1972 through April 1975. Sonagrams and tape recordings of adult red wolf sounds were used to describe flat howls, barking howls, combination howls, yip howls, whimpers, growls, barks, and choruses. The flat howl of red wolves and coyotes was compared because this was the most useful sound for field recognition of unknown canids. On the average, red wolf flat howls were of longer duration and lower Hertz or cycles/second (Hz) than coyote flat howls. There were also differences in beginning, ending, and manner of Hz change of the howl of red wolves and coyotes, but these differences were not absolute.

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... Previous papers have considered the behavioural and ecological issues of wolf howling in relation to the defence of resources and aggressive behaviour (Harrington 1987; Harrington & Mech 1979; 1983), to timing of wolf activity (Harrington & Mech 1978b; Gazzola et al 2002; Nowak et al. 2007), or to wolf pack census technique (Harrington & Mech 1982; Fuller & Sampson 1988). Some studies considered the acoustic structure of North American wolf howls (Theberge & Falls 1967; Harrington & Mech 1978a; Harrington 1989; Tooze et al. 1990); while others, carried out in Eurasia, with the exception of Nikolskii et al. (1986) and Nikolskii & Frommolt (1989) that were performed in nature, were limited to captive wolves (Nikolskii & Frommolt 1985; Schassburger 1987; 1993; Frommolt 1999; Palacios et al. 2007) and failed to account for the actual influence of captivity on vocalizations (McCarley 1978). The fundamental frequency (FO) of adults' howls ranges between 150 Hz and more than 1,000 Hz (Theberge & Falls 1967; Harrington & Mech 1978a; Harrington 1989; Tooze et al. 1990), which is usually the dominant frequency (Theberge & Falls 1967; Shassburger 1993). ...
... Each answer was classified on the basis of the number of vocalising individuals, as either "choral response" (two or more responding individuals) or "single response" (one responding individual). Since the aim of this study was to characterize howls only, the whimpers, barks and growls that often occurred in the choral responses (Mech 1966; Joslin 1967; Harrington & Mech 1978b; McCarley 1978) were excluded from the analysis. From 2003 to 2008 we analysed 37 howls extracted among the single responses by 3 subjects, and 128 howls belonging to the choruses of 7 packs. ...
... Resolutions and variables were consistent with those used in previous works on wolf vocalizations (Tooze et al. 1990; Palacios et al. 2007). Amplitude parameters and number of harmonic overtones were not considered since they generally depend on the distance between the animals and the recording site (Harrington & Mech 1978a; McCarley 1978). ...
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Italian wolf howls are described for the first time from observations between 2003–2008 of a population living in eastern Tuscany, central Italy. A sample of 37 howls selected among single responses and 128 howls included in the choruses of 7 free ranging packs was recorded and analysed. The mean fundamental frequency of the howls ranged between 274–908 Hz. Two main structures recognised by means of multivariate explorative analysis, in particular Principal Component and Cluster Analysis, were ascribed to breaking and flat howls. Discriminant Function Analysis was applied to the recognised groups with the aim to find a general rule for classification. Howls with different features were correctly assigned to the groups obtained by explorative analysis in 95.8% of cases. The analysis of the variables characterising the structure of the howls suggests that maximum frequency and range of fundamental frequency are the most important parameters for classification, while duration does not appear to play any significant role.
... Corbett & Newsome (1975) reported that wild dingoes bark-howled to warn pups and conspecifics of an immediate threat and the findings here support this hypothesis. Bark-howling has also been identified in coyotes (Lehner, 1978), and red wolves (McCarley, 1978). McCarley (1978) agreed with Lehner's (1978) hypothesis that bark-howls served as alarm and threat signals. ...
... Bark-howling has also been identified in coyotes (Lehner, 1978), and red wolves (McCarley, 1978). McCarley (1978) agreed with Lehner's (1978) hypothesis that bark-howls served as alarm and threat signals. The observation that barkhowls were produced in response to a snake supports the warning function but not the threat function of bark-howls in dingoes. ...
... Howls have previously been proposed to allow individual recognition in North American timber wolves (Tooze et al., 1990) and Iberian wolves (Palacios et al., 2007). When studying red wolves, McCarley (1978) further divided the howl category into 'flat howls', 'barking howls', 'combination howls' and 'yip howls'. We also found evidence of all four howl types, but the majority were flat howls. ...
Article
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The classification and description of a species' acoustic repertoire is critical to our understanding of broader behavioural patterns and provides data for future cross-species comparative studies. To date, our understanding of canid auditory communication remains limited as full acoustic repertoires have been compiled for only nine of 36 extant species. Dingoes (Canis lupus dingo) are apex predators in Australia, and while their ecology and life-history patterns have been extensively studied, their communication system remains poorly understood. Early studies noted four sound types, but whether this represented the dingoes' full range of laryngeal and nasal sounds was unknown. We aimed to quantitatively and qualitatively describe the full acoustic repertoire of dingoes. We identified nine discrete vocalisations (i.e., laryngeal sounds) and two nasal sounds. Of these nine vocalisations, five were previously identified as common to other canid species. This study also revealed that dingoes possess a graded acoustic communication system, where the gradual change in acoustic characteristics of discrete vocalisations was noted. Dingoes also uttered 'mixed sounds', a finding in concordance with previous studies of social canids. Additionally, we established an ethogram to further our understanding of the contexts in which dingo acoustic communication occurs.
... Групповой вой койотов описали Макчарли и Ленер [McCarley, 1975;Lehner, 1978], хор американских красных волков (Canis rufus) -Макчарли [McCarley, 1978]. Все три работы иллюстрированы сонограммами. ...
... Макчарли [McCarley, 1978] обнаружил сходство группового воя волков с хором койотов: за несколькими начальными звуками плавного воя одного или двух животных (модификация «А» у шакалов) следует комбинированный вой, который затем сочетается с визгом-воем (модификации «Б» и «В» у шакалов). Во всех случаях длительные звуки ближе к концу хора короче по длительности, чем предшествующие им (эта особенность полностью соответствует сокращению длительности к концу группового воя шакалов, см. ...
... Сонограммы группового воя койотов и волков, заимствованные из цитированных выше работ Макчарли [McCarley, 1975[McCarley, , 1978, приведены на рис. 65, 66. ...
... Researchers conduct acoustic surveys using human-simulated howls or broadcasted, previously recorded wolf howls to detect and monitor wolf packs via their vocal responses (Blanco and Cortés 2012, Passilongo et al. 2015, Palacios et al. 2017. Moreover, wolves are known to vocally respond to other sounds, such as sirens (McCarley 1978). Great Horned Owls emit a vocalization called a "hoot" that functions to establish and maintain a territory and to announce their presence (Kinstler 2009, Odom et al. 2013. ...
... We surmise that the wolf was vocalizing for very different reasons. Wolves are known to respond to other sound sources, such as human imitations of howls or sirens (McCarley 1978, Palacios et al. 2017). This can be explained by the similar acoustic structure of all these sounds: long and harmonic with similar frequency range. ...
Article
During summer 2019, we recorded an apparent vocal interaction, lasting just under 4 min, between a pair of Great Horned Owls (Bubo virginianus) and a gray wolf (Canis lupus) in Yellowstone National Park. To our knowledge, this is the first report of such an acoustic interaction in the scientific literature. The increased use of passive acoustic recorders, which record spontaneous vocalizations emitted by animals over long periods, will allow us to better document and study the importance of such interspecific interactions.
... Chorus howls have been described as a vocalization in which one wolf begins howling, with other members joining in until several or all members of a pack are howling together (Joslin 1967). Howls in the context of a chorus vary more than those produced by lone individuals (Harrington 1989;McCarley 1978). Choruses can be discordant, resulting in a change in the overall structure of the chorus, and this is often linked to the presence of various group mates possibly originated by a change in physiological arousal and/or to foster group cohesion (Harrington and Asa 2003;Schassburger 1993). ...
Article
Wolf packs perform group vocalizations called chorus howls. These acoustic signals have a complex structure and could be involved in functions such as strengthening of social bonds, territory advertisement, or spacing between packs. We analyzed video recordings of 46 chorus howls emitted by 10 packs of wolves held in captivity, in order to investigate whether sex, age, social status, pack, or individual influence the way wolves participate in a chorus. We found that, during a chorus, wolves vocalized 63% of the time, with the howl being the most common vocalization (36% of the chorus duration), followed by woa (13.5%), other vocalizations (11.8%), and bark (1.7%). The main factor affecting the vocal behavior of wolves was age, since young wolves vocalized less and uttered shorter acoustic signals than adults. The discriminant analysis carried out with the wolves of Cañada Real pack assigned 89.3% of the cases to the correct individual, which is much better than the assignment expected by chance, suggesting that individuals could have a unique vocal usage during a chorus howl, mainly due to the use of howls and woa-woa howls. Based on our results, we propose that in the context of a chorus the woa-woa howl is important, although further research is needed to address this issue properly.
... can have a more active role behaviorally as exemplified by the vocalizations of most animals [e.g., bird songs (Pepperberg, 1981;Derrikson, 1988), canid growls (Lehner, 1978;McCarley, 1978;Moehlman, 1987)]. As indicated above, however, signals do not function alone (Smith, 1981). ...
Article
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Includes bibliographical references (p. 166-183). Vita. Thesis (Ph. D.)--Texas A & M University, 1996. "Major Subject: Wildlife and Fisheries Sciences."
... Spectrogram parameters selected for the analysis were: 2048point discrete Fourier transform; frequency resolution: 21.5 Hz; filter bandwidth: 37.5 Hz; time overlap: 10 msec; Hanning window. For the purposes of this study, we analysed only howling (flat and breaking) and did not consider other types of vocalizations such as whimpers, barks and growls, that often occur in choral responses (MECH 1966;JOSLIN 1967;HARRINGTON & MECH 1978b;MCCARLEY 1978). Howls by pups, recognizable until 6/7 months of age for their high frequency and instability of the vocal structure due to physical growth (HARRINGTON & MECH 1978b;HARRINGTON & ASA 2003), were not taken into consideration. ...
Article
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Acoustic communication conveys a variety of information that is a helpful tool for animal conservation. The wolf is an elusive species, which can be detected through the howls that individuals emit. In this study we investigated the acoustic features of wild wolf pack howls from five locations in the province of Arezzo, Italy. We tested the hypothesis that each group had a distinctive vocal signature. Our results showed that these wolf packs emitted howls with significantly distinctive acoustic structures. We hypothesized that group-specific vocal signatures require temporal stability to be functional. Indeed, we did not find any statistical differences in howls collected from the same location during the same season or for 2 consecutive years. We suggest that the acoustic features of howls can be used to distinguish wolf packs in the wild.
... Vocalizing mammals usually have many tonal sounds and a few harsh noises (Rowel1 & Hinde, 1962 ;Andrew, 1963 ;Kiley, 1972 ;McCarley, 1975McCarley, , 1978Harrington & Mech, 1979 ;Brady, 1981 ;Hall et al., 1988). Among the eight species of the family Cervidae whose sonagrams are known (the elk Cervus canadensis by Struhsaker, 1967, andBowyer &Kitchen, 1987 ; the white-lipped deer C. albirostris by Miura et al., 1988; the red deer C. elaphus by McComb, 1988 ; the sika deer C. nippon by Minami, 1981, Miura, 1984a, and in the present study; the reindeer Rangifer tarandus by Espmark, 1971Espmark, , 1975 Reeves's muntjac Muntiacus reevesi by Yahner, 1980; the white-tailed deer by Richardson et al., 1983 ; and PSre David's deer Elaphurus davidianus by Wemmer et al., 1983), most of their sonagraphic structures are tonal sounds. ...
Article
A total of 620 calls of six sex/age classes of the sika deer Cervus nippon was tape-recorded through seasons and sonagraphically analyzed. Of five call groups identified, two were loud clear calls with high fundamental frequencies. The loudest and longest of these was used for territorial advertisement, while the other, used when alarmed, was high and short. Two other call groups consisted of clear calls or harsh noises, involving many call types the physical structure of which overlapped each other ; these two groups were used for maternal contact, sexual contact, attack, or appeasement at close range. The five call groups were further subdivided into 13 call types. Ten were given by adult males and seven by adult females. Repertoires of subadults and yearlings consisted of parts of the repertoires of adults of the respective sexes. Males increased their range of call types and frequency of calling during the rutting season, while most female calls were used for maternal contact regardless of seasons. The fundamental frequency tended to decrease with age and was higher for adult females than for adult males.
... Barking is reported in the vocal repertoire of almost all the wild Canidae (Cohen and Fox, 1976), including wolves (Cohen and Fox, 1976;Schassburger, 1993;Feddersen-Petersen, 2000;McCarley, 1978), coyotes (Lehner, 1978;Mitchell et al., 2006;McCarley, 1975), foxes (Cohen and Fox, 1976;Frommolt et al., 2003;Murdoch et al., 2008;Brady, 1981;Darden and Dabelsteen, 2006), jackals (Tembrock, 1976), African wild dogs, Lycaon pictus (Robbins, 2000), bush dogs, Spethos venaticus (Brady, 1981), dingos (Corbett, 2004), and New Guinea singing dogs (Koler-Matznick et al., 2003;Brisbin et al., 1994). Virtually identical to domestic dog barking in its acoustic character, each species appears to exhibit a somewhat narrower range of variability in tonality/noise and mean pitch. ...
Article
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Barking is most often associated with the domestic dog Canis familiaris, but it is a common mammalian and avian vocalization. Like any vocalization, the acoustic character of the bark is likely to be a product of adaptation as well as an expression of the signaler's internal motivational state. While most authors recognize that the bark is a distinct signal type, no consistent description of its acoustic definition or function is apparent. The bark exhibits considerable variability in its acoustic form and occurs in a wide range of behavioral contexts, particularly in dogs. This has led some authors to suggest that dog barking might be a form of referential signaling, or an adaptation for heightened capability to communicate with humans. In this paper we propose a general 'canonical' acoustic description of the bark. Surveying relevant literature on dogs, wild canids, other mammals and birds, we explore an alternative functional hypothesis, first suggested by [Morton, E.S., 1977. On the occurrence and significance of motivation-structural rules in some bird and mammal sounds. Am. Nat. 111, 855-869] and consistent with his motivational-structural rules theory: that barking in many animals, including the domestic dog, is associated with mobbing behavior and the motivational states that accompany mobbing.
... Of particular interest in this study are unimodal complex calls termed 'bark-howls', which are stereotyped vocalisations, formed from the successive and uninterrupted production of a bark and a howl segment (Fig. 1, see Video S1 in the online version at DOI: 10.1016/j.beproc.2016.06.012). Barkhowling has also been observed in wolves, C. lupus (Cohen and Fox, 1976), coyotes, C. latrans (Lehner, 1978) and red wolves, C. rufus (McCarley, 1978) although the lack of clear descriptions makes it difficult to assess the extent of the similarities between the different species' bark-howls. Anecdotal evidence indicates that wild dingoes will produce bark-howls upon detecting a human observer, and these vocalisations have been observed to elicit escape behaviours in nearby pups (Corbett, 2001;Purcell, 2010). ...
Article
Dingoes (genus Canis) produce a stereotyped bark-howl vocalisation, which is a unimodal complex signal formed by the concatenation of two call types (a bark and a howl). Bark-howls may function as alarm signals, although there has been no empirical investigation of this vocalisation’s structure or function. We quantified the content and efficacy of the bark and howl segments separately and when combined, using 140 calls from 10 individuals. We found that both segments are individually distinctive, although howl segments are more accurately classified, suggesting a higher level of individuality. Furthermore, howls convey signature characteristics that are conserved across different contexts of production, and thus may act as ‘identity signals’. The individual distinctiveness of full bark-howls increases above that of isolated segments, which may be a result of selection on improved signal discriminability. Propagation tests revealed that bark-howls are best described as medium-range signals, with both segments potentially allowing for individual discrimination up to 200 m regardless of environmental conditions. We discuss our findings regarding the fitness benefits of encoding identity cues in a potential alarm call and propose additional hypotheses for the function(s) of bark and howl segments.
... Chorus howlings are complex, multicomponent signals that include several elements (Theberge and Falls, 1967;Harrington and Mech, 1982;Harrington, 1989); indeed, choruses begin with simply-structured howls (Harrington, 1989), but also other kind of calls * Corresponding author Email address: dpassilongo@uniss.it (Daniela P ) often occurred in the choral responses (Mech, 1966;Joslin, 1967;Harrington and Mech, 1978;McCarley, 1978) as the chorus progressed. Within a wolf pack, chorus may be useful to promote the joining of members (Mech, 1966;Theberge and Falls, 1967) and to communicate information on the individual identity and the location (Theberge and Falls, 1967;Tooze et al., 1990;Zaccaroni et al., 2012). ...
Article
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Wolf choruses (Canis lupus) are complex, multicomponent signals, composed by a series of different vocalizations emitted by a pack. Although howls, the main component, have been highly studied, poor attention has been drawn upon the other vocalizations of the chorus. In this study, we investigate the structure of the chorus by means of the analysis and the quantification of the different components, taking advantage both of the digital sound recording and analysis, and of the modern statistical methodologies. We provide for the first time a detailed, objective description of the types of call emitted during the wolf howlings, combining spectrographic examinations, spectral analyses and automated classifications, with the aim to identify different types of call. Our results show that wolf choruses have a rich, complex structure, that reveals six other types of call, to be added to those howls already described in literature. Wolf choruses are typically composed by other three different types of calls: the bark, i.e. relatively long calls characterized by low frequencies and the presence of harsh components (deterministic chaos); the whimper, characterized by a harmonic structure and a very short duration; and the growl, a call with a noisy structure, low frequencies but relative long duration. Although further investigations are necessary to understand the meaning of the different calls, this research provides a basis for those studies that aim to compare wolves and other canids vocal behaviour.
... In the wild species of Canidae, barks are almost solely used in contexts where they convey warning or different levels of aggression [gray wolves: Lehner, 1978;Schassburger, 1987Schassburger, , 1993; African wild dogs (Lycaon pictus): Robbins, 2000; crab-eating foxes (Cerdocyon thous), bush dogs (Speothos venaticus), maned wolves (Chrysocyon brachyurus): Brady, 1981; red wolves (Canis rufus): McCarley, 1978;coyotes (Canis latrans): Lehner, 1978; red foxes (Vulpes vulpes): Newton-Fisher, Harris, White, & Jones, 1993;and dholes (Cuon alpinus): Volodin, Volodina, & Isaeva, 2001]. More importantly in a recent study, it was found that even in the dingo (Canis lupus dingo), the wild dog of Australia, barks occur only in the original, agonistic context (Déaux & Clarke, 2013). ...
Article
Interspecific communication provides good opportunity for studying signal evolution. In this theoretical paper, we hypothesized that vocal signaling in dogs may show specific changes that made it more suitable for interspecific communication in the anthropogenic niche. We assumed that (1) some dog vocalizations will diverge from the corresponding exemplars of wolves; (2) they provide comprehendible affective, indexical, and contextual information for humans; (3) some aspects of dog vocalizations are more typical for the interspecific than for the intraspecific domain. We found that the most unique type of vocalization in the dog is barking. We proved that human listeners can contextually categorize dog barks, as well as attribute distinct inner states of dogs based on the barks. We found that dogs are sensitive to both contextual and individual-specific features of other dogs' barks. However, dogs showed almost no response to the bark emitted in isolation, which is one of the easiest to recognize by humans, indicating the possibility of a specific, new communicative role for barks, not present in its original function. Our conclusion is that the qualitative and quantitative proliferation of barks can be explained by mechanisms of evolution such as ritualization and adaptive radiation. Barks became suitable for conveying a more various set of information than the original barks of wolves did. Barks also became typical in such contexts where originally they were not used - such as the contact seeking calls of isolated specimens, apparently targeted at the human, and not at a canine audience.
... Ils sont structurellement complexes et variables et peuvent donner des informations relatives à l'effectif de la meute . Les chorus débutent généralement par des hurlements simplement structurés, puis d'autres types de vocalisations interviennent au fur et à mesure de leur progression McCarley, 1978 ;. Après les hurlements, les aboiements sont les plus communs dans les chorus ). ...
Thesis
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The growing number of studies carried out in recent years has shown that bioacoustics is particularly interesting for the monitoring of secretive species. The emergence of autonomous recording devices, combined with new methods of analysis, have recently contributed to the increase of studies in this field. Over the last 30 years, many bioacoustic studies have been developed for the Grey wolf (Canis lupus), a secretive large carnivore known for its howls spreading over distances up to several kilometers. These researches notably aimed to improve its monitoring, which is complex because of the strong wolf dispersal capacities over long distances, the large extent of their territories and the various natural contexts in which they live. In this context, this PhD thesis was organized around three research axes. The first two axes focused on the contribution of passive bioacoustics for the Grey wolf monitoring in the field. By combining acoustic, statistical and cartographic analysis, the first objective was to develop a spatial sampling method adapted to large study areas for the detection of wolf howls by using autonomous recorders. Then, the same protocol was used to investigate the possibility to localize wolves thanks to their howls. Field experimentations, conducted in mid-mountain (Massif des Vosges) and lowland (Côtes de Meuse) environments, in two study areas of 30 km² and with an array of 20 autonomous recorders, demonstrated the high potential of passive bioacoustics for the Grey wolf monitoring. Indeed, nearly 70% of broadcasts (synthetic sound with similar acoustic properties to howls) were detected by at least one autonomous recorder in mid-mountain environment and more than 80% in lowland environment, for sound source-recorders distances of up to 2.7 km and 3.5 km respectively. By using statistical model and Geographic Information System, the detection probability of wolf howls was modeled in both study areas. In the mid-mountain environment, this detection probability was high or very high (greater than 0.5) in 5.72 km² of the study area, compared with 21.43 km² in lowland environment. The broadcast sites were localized with an overall mean accuracy of 315 ± 617 (SD) m, reducing until 167 ± 308 (SD) m after setting a temporal error threshold defined from the data distribution. The third axe focused on the application of acoustic diversity indices to estimate the number of howling wolves in choruses and thus to contribute to pack size monitoring. Index values of the six indices (H, Ht, Hf, AR, M, and ACI) were positively correlated with the number of howling wolves in the artificial tested choruses. Interesting size predictions based on real choruses were obtained with one of the indices (ACI). The effects of several biases on the reference values for the acoustic indices were then explored, showing that three of them were relatively insensitive (Hf, AR and, ACI). Finally, results obtained with autonomous recorders confirm the real potential of passive acoustic methods for detecting the presence of wolves but also for localizing individuals with high precision, in contrasting natural environments, at large spatial and temporal scales. The use of acoustic diversity indices also opens new perspectives for estimating pack sizes. All of the promising methods emerging from this thesis require now further investigations before considering a concrete application for monitoring the Grey wolf in its natural environment.
... Ils sont structurellement complexes et variables et peuvent donner des informations relatives à l'effectif de la meute . Les chorus débutent généralement par des hurlements simplement structurés, puis d'autres types de vocalisations interviennent au fur et à mesure de leur progression McCarley, 1978 ;. Après les hurlements, les aboiements sont les plus communs dans les chorus ). ...
Thesis
Le nombre croissant de travaux réalisés ces dernières années a montré que la bioacoustique est particulièrement intéressante pour le suivi d’espèces discrètes. L’émergence de dispositifs d’enregistrement autonomes, associée à de nouvelles méthodes d’analyse, ont récemment participé à l’accroissement des études dans ce domaine. Au cours des 30 dernières années, le Loup gris (Canis lupus), mammifère carnivore aux mœurs discrètes connu pour ses hurlements de longue portée, a fait l’objet de nombreuses études acoustiques. Ces dernières visaient notamment à améliorer son suivi, qui s’avère complexe du fait des grandes capacités de déplacement des loups, de l’étendue de leurs territoires et de la diversité des milieux dans lesquels ils vivent. Cependant, la bioacoustique passive a jusqu’alors très peu été exploitée pour le suivi du Loup. C’est dans ce contexte que la présente thèse s’est organisée autour de trois axes de recherche. Les deux premiers axes portent sur l’apport de la bioacoustique passive pour le suivi du Loup gris en milieu naturel. En combinant des analyses acoustiques, statistiques et cartographiques, le premier objectif a été d’élaborer une méthode pour l’échantillonnage spatial de vastes zones d’étude, afin d’y détecter des hurlements de loups à l’aide de réseaux d’enregistreurs autonomes. Ce même dispositif a ensuite permis, dans un second temps, de tester la possibilité de localiser les loups grâce à leurs hurlements. Les expérimentations conduites en milieu de moyenne montagne (Massif des Vosges) et de plaine (Côtes de Meuse), sur deux zones d’étude de 30 km² et avec un réseau de 20 enregistreurs autonomes, ont permis de démontrer l’intérêt de la bioacoustique passive pour le suivi du Loup gris. En effet, près de 70% des émissions sonores (son synthétique aux propriétés similaires à celles de hurlements de loups) ont été détectés par au moins un enregistreur autonome en milieu de moyenne montagne et plus de 80% en milieu de plaine, pour des distances enregistreurs– source sonore atteignant respectivement plus de 2.7 km et plus de 3.5 km. Grâce à un modèle statistique et à un Système d’Information Géographique, la probabilité de détection des hurlements a pu être cartographiée sur les deux zones. En moyenne montagne, elle était forte à très forte (>0.5) sur 5.72 km² de la zone d’étude, contre 21.43 km² en milieu de plaine. Les sites d’émission ont été localisés avec une précision moyenne de 315 ± 617 (SD) m, réduite à 167 ± 308 (SD) m après l’application d’un seuil d’erreur temporelle défini d’après la distribution des données. Le troisième axe de travail porte quant à lui sur l’application d’indices de diversité acoustique pour estimer le nombre d’individus participant à un chorus et ainsi contribuer au suivi de l’effectif des meutes. Les valeurs obtenues pour les six indices (H, Ht, Hf, AR, M et ACI) étaient corrélées avec le nombre de loups hurlant dans les chorus artificiels testés. De bonnes prédictions de l’effectif ont été obtenues sur des chorus réels avec l’un de ces indices (ACI). L’influence de plusieurs biais sur la précision des prédictions de chacun des six indices a ensuite pu être étudiée, montrant que trois d’entre eux y étaient relativement peu sensibles (Hf, AR et ACI). Finalement, les résultats obtenus avec les enregistreurs autonomes montrent le potentiel des méthodes acoustiques passives pour la détection de la présence de loups mais aussi pour les localiser avec une bonne précision, dans des milieux contrastés et à de larges échelles spatiale et temporelle. L’utilisation des indices de diversité acoustique ouvre également de nouvelles perspectives pour l’estimation de l’effectif des meutes. Prometteuses, l’ensemble des méthodes émergeant de ce travail nécessite à présent quelques investigations complémentaires avant d’envisager une application concrète pour le suivi du Loup gris dans son milieu naturel.
Chapter
The domestic dog (Canis lupus f. familiaris) and cat (Felis silvestris f. catus), which are quite vocal by mammalian standards, are not good representatives of the acoustic activities of fissiped carnivores. Fissipeds are generally thought of as mammals that communicate with smell rather than with vocalizations (Gorman and Trowbridge, this volume). Nevertheless, several carnivore acoustic signals like the howling of gray wolves (Canis lupus), the whooping of spotted hyenas (Crocuta crocuta), and the roaring of African lions (Panthera leo) capture the human imagination as few other animal sounds do. It is probably no accident that wolf howling—unlike other acoustic signals of carnivores—is one of the best-studied mammalian vocalizations (Theberge and Falls 1967; Cohen and Fox 1976; Tembrock 1976a, 1976b; Fox and Cohen 1977; Shalter et al. 1977; Field 1978, 1979; Fox 1978; Harrington and Mech 1978a, 1978b, 1979, 1982, 1983; Schassburger 1978; Klinghammer and Laidlaw 1979; Filibeck et al. 1982; Harrington 1986, 1987; Nikolskii and Frommolt 1986).
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