Howling as a Means of Communication in Timber Wolves

The communicatory function of howling was studied in three adult male timber wolves ( Canis lupus ). Approximately 700 howls were subjected to spectrographic and auditory analysis. The fundamental frequency of howls was divided into beginning, mid-section, and ending, and each section was studied separately. Harmonic features were also examined. Much variation was found within the howls of each individual. However, unique features were found in all howls of two wolves, of potential value in individual recognition. The variation in characteristics of the fundamental within howls of individuals was tested to see if it related to features of the animal's behavior or environment. Eleven significant relationships were found. The characteristics involved were considered potentially functional in conveying information of a behavioral or environmental nature. Auditory discrimination was studied by stimulus-response experimentation involving simulated wolf howls by humans. By either howling in response or remaining silent, one wolf demonstrated an ability to detect the slight difference between live howls and recorded, played-back howls. This ability enhances the possibility that individual recognition and conveyance of information may take place by means of differences in howls. Analysis of the circumstances in which spontaneous howling (no known auditory stimulation) occurred demonstrated that isolation resulted in increased howling. A form of long-distance communication is important to a social unit whose members are often separated. This study suggests that howling identifies the species, functions in the location of specific animals, provides specific information about the howling animal, and is, therefore, of great value in coordinating the social activities of wolves.