Analyse des tactiques comportementales chez les jeunes marmottes alpines. Behavioural tactics analysis in young Alpine marmots.

Résumé

Behavioural ontogenesis is one of the determining factors of individual feature. So, it represents an essential source of phenotypic variability in natural populations. Therefore, it is an important part of the individual fitness. Since Bateman (1948) and Trivers (1972) it is largely accepted that males and females differ in their reproductive strategies. We investigated for early differences in behavioural tactics of young marmots, during the first year of life, which could affect the both sex reproductive strategies. Our study mainly dealt with time-budget and space occupation. Five litters were observed in the valley of la Grande Sassière (French Alps), during four periods: I - from 0-15 days, II - from 15-30 d, III - from 30-60 d after emergence (young) and IV - the next spring after the first hibernation (yearling). Fifteen minuts of focal animal sampling and scan animal sampling (Altman-1974) were used to collect data, respectively on time-budget and space occupation. More than 250 h of observation allowed us to get 297 focals and 1769 scans. We performed on the first data set (time-budget) a correspondance analysis under period and sex constraints, whereas two-way ANOVA and c2 tests were performed on the second (space occupation). Time-budget analysis revealed the same pattern of seasonal modifications for both sexs. Moreover, the great importance of interactions (allo-grooming and allo-sniffing) characterized females as early as the first period whereas males were characterized by play only the spring after the first hibernation. Space occupation analysis supports such a great period effect and gives us some indications for an inter-sex rapprochement. Finally we examined play functions and their social implications for Alpine Marmots.