Circannual rhythms of food consumption, body mass and metabolism in yellow-bellied marmots [Rythmes circannuels de consommation alimentaire, de la masse corporelle et du métabolisme chez la marmotte à ventre jaune].

Résumé

Des cycles circannuels de consommation alimentaire, de masse corporelle et de taux métaboliques existent en conditions constantes. 1- Food consumption body mass (Bm), and metabolic rate (MR) were measured under constant laboratory conditions over 25 months for montane-mesic (MM) marmots, while food consumption and Bm were measured over 18 months for lowland-xeric (LX) marmots. 2- Marmots exhibit circannual cycles in all three parameters with maximum (max) and minimum (min) values of MR preceding the max and min values of food consumption by at least l month and the max and min values of Bm by at least 2 months. 3- The max food consumption and Bm of the LX population occur at least 2 months prior to those of the MM group. This interpopulation phase difference in cycles corresponds well with observed differences in above-ground activity between the two populations. 4- The circannual cycle of MR is suggested as the driving force underlying the cycles of food consumption and Bm.