Variabilité de la structure spectrale du cri d'alarme de quelques espèces de marmottes en fonction du contexte. Situation variability of alarm call spectral structure of some marmot species.

Résumé

More in detail we investigated situation variability of steppe marmot's (Marmota bobac) alarm call. Alarm call of this species consists of single notes. We decided, that situation variability in case of increasing danger is expressed by change of notes parameters from the beginning of a vocal sequence to it's end. Five parts of alarm call can be distinguished by expression of their production when observer approaches to marmot. They are the following: 1) initial notes; 2) notes at the middle of sequence; 3) last notes before going into a burrow; 4) notes at the moment of going into a burrow; 5) notes from a burrow. Nine parameters of the notes from different parts of sequence were compared. The pause between high- and low-frequency components; the beginning of fundamental frequency and characteristic of frequency modulation of high-frequency component appeared to be the most stable in different situations while maximum, terminal and dominant frequencies of fundamental of high-frequency component and duration of high- and low-frequency components are the most variable. When danger increases the alarm call changes in the following way: maximum, terminal and dominant frequencies of high-frequency component decrease as well as it's duration; dominant frequency of low-frequency component decreases, decreases it's duration in the parts of 1; 2; 3 and increases in the parts of 4; 5. Notes in the distinguished parts of alarm call significantly differed from each other.