Vocalization of European wolves (Canis lupus lupus L.) and various dog breeds (Canis lupus f. fam.)
Abstract. Barking in domestic dogs still remains a topic of controversial discussions. While some authors assess dogbarking an acoustic means of expression becoming more and more sophisticated during domestication, others name this sound type "non-communicative". Vocal repertoires as works on individual sound types are rare, however, and there has been almost no work done on Iow-intensity, close-range vocalizations, yet such types of vocalization are especially important with the more social canids, hence, with the human-dog-communication and understanding of dogs. Most of the investigations published so far are based on auditive sound impressions and lack objectivity. The principal method used in this study was sonagraphic. This facilitates the identiftcation of sounds and reveales, whether subjective Classification can be verified by objectively measured parameters. Finally, meanings, funetions and emotions were examined for all the major sounds described and are discussed in terms of relationships between sound structure and Signal function, signal emission and social context as behavioural response, and overlapping Channels of communication. Ontogeny of acoustic communication in 11 European wolves has been compared to various dog breeds (8 Standard Poodles, 8 Toy Poodles, 15 Kleine Münsterländer, 11 Weimaraner Hunting Dogs, 16 Tervueren, 12 American Staffordshire Terriers, and 13 German Shepherds, 12 Alaskan Malamutes, and 9 Bull Terriers) from birth up to 8 (12) weeks resp. 4 (12) months of age. Noisy and harmonic sound groups were analysed separately as overriding units. Following parameters were used: fmax=maximum of spectrographic pietured sounds (Hz), xfo=mean of the lowest frequency band of harmonic sounds (Hz), xfd = mean of the frequency of strongest amplitude of noisy sounds (Hz), delta f = frequency range of sounds (Hz), duration of sounds (ms). Statistical analysis was run on "Statistica", Release 4,0. Within the sound type barking 2 to 12 subunits were classified in the different breeds, aecording to their context-speeifie spectrographic design, and behavioural responses. Categories of function / emotion include f.e. social play, play soliticing, exploration, caregiving, social contact and "greeting", loneliness, and agonistc behaviours. "Interaction" was the most common category of social context for masted barkings (56% of oecurences). Especially close-range vocalizations, conceming the major sound type of most domestic dogs, the bark, evolved highly variable. However, the ecological niche of domestic dogs is highly variable, just as the individual differences in the dogs are, which seem to be breed-typical to a great extent. Thus, complexity within the dog's vocal repertoire, and therefore enhancement of its communicative value, is achieved by many subunits of bark, some standing for specific motivations, informations and expressions. Complexity within the dogs'vocal repertoire is extended by the use of mixed sounds in the barking context. Transitions and gradations to a great extend oeeur via bark sounds: harmonic, intermediate and noisy subunits.