March 29. - 2022

Daily Heterotherm Patterns Shift Into Multiday Torpor Patterns During Winter in Monitos

In a study conducted by scientists in Chile at Instituto de Ciencias Ambientales y Evolutivas, Center of Applied Ecology and Sustainability (CAPES), Millenium Institute for Integrative Biology, and Instituto de Biología, core body temperature was used to determine torpor and hibernation periods in Monito del Monte marsupials (Dromiciops gliroides) during winter. Torpor bouts were detected both in lab settings and in the field.

Body temperature measured hourly
Eight monitos (~25g) were captured and implanted intraperitoneally with Star-Oddi’s DST nano-T temperature loggers, which were set to collect data hourly for one winter of 2019 in Chile (March through November). Two of the loggers were then reused in two newly captured animals for one month ramp experiments in the winter of 2020. All the animals were returned to the wild after the study, and more monitos were monitored in the wild.

Monitos go into torpor all year long even in warm periods
Around 150 torpor bouts with periods of normal body temperature in between were detected. Overall, 25 individuals were monitored with weekly visits in the wild and monthly torpor periods were recorded, with increase in winter, but never zero even during warm summer days. The results of this study show that the monitos go into short bouts of torpor, even in the reproductive period, independently of the ambient temperature. They can go into seasonal torpor of maximum 5 days.

Daylight and food availability predict torpor
The only predictable variables of torpor in this little South American marsupial seem to be the photoperiod and food availability. Overall, monitos species expresses dynamic torpor form that varies between short periods of torpors to hibernation in correlation with diminishing daylight.

The paper was published in Frontiers in Physiology – Integrative Physiology and can be accessed here