Xenarthrans could be used as models to obtain valuable information about how physiology affects mammal behavior. This is probably an adaptation to their physiological constraints and limited thermoregulatory capabilities. At lower temperatures, yellow armadillos tended to leave their burrows earlier and were active for longer periods. The proportion of activity overlap was 0.28 between the species, occurring primarily at the beginning of the night.
However, nine-banded armadillos presented a bimodal activity pattern, becoming active for a short period in the middle of the morning and/or afternoon. Yellow arma-dillos were active mainly during the daytime and in the beginning of the night, while nine-banded armadillos were active mainly during the night. By monitoring the temperature of the environment (air temperatures and burrow temperatures), we inferred when the armadillo was active (above ground) or inactive (inside the burrow).
We captured seven yellow armadillos and three nine-banded armadillos and fitted them with very high frequency radios and temperature loggers. We report the effect of daily mean ambient temperature on activity onset and duration of these armadillos. In this study, we characterized the activity patterns and estimated the activity overlap between two armadillo species (Dasypus novemcinctus and Euphractus sexcinctus) in the Pantanal wetlands of Brazil. pichiy naturally occurs farther south than any other armadillo species. In combination with their ability to hibernate and to respond to a reduced insect abundance by ingesting other food items, this physiological adaptation allows pichis to better cope with food shortages and a more extreme climate than other armadillos. Nine out of ten prolonged torpor bouts occurred in individuals feeding on a low-quality diet, suggesting that pichis are able to enter prolonged periods of torpor during severe environmental stress. Five individuals entered prolonged torpor bouts lasting more than 24 h, two of them repeatedly.
All individuals entered spontaneous daily torpor, but those receiving a low-quality diet had significantly lower daily mean and minimum Tsc, spent more time at Tsc below their individual lower limit of normothermia, and had a higher Heterothermy Index than controls. We recorded body temperature (Tsc) changes in 10 semi-captive, adult female pichis using dataloggers implanted subcutaneously during periods of 21 days. We experimentally tested whether food quality influences torpor frequency and depth in the pichi (Zaedyus pichiy), a small, opportunistically omnivorous armadillo endemic to arid and semi-arid habitats of southern South America. We conclude that the pichi is a true hibernator and can enter daily torpor outside of the hibernation season.ĭaily torpor is a physiological adaptation that allows mammals to cope with energetic challenges associated with unpredictable periods of food shortage. After the hibernation season, daily torpor bouts of 4 to 6 h occurred irregularly, with T(sc) dropping to as low as 24.5 degrees C. These events were interrupted by periods of euthermia of 44+/-38 h with a T(sc) of 29.1+/-0.7 degrees C. All individuals entered hibernation, characterized by torpor events of 75+/-20 h during which the subcutaneous temperature (T(sc)) decreased to 14.6+/-2.1 degrees C. We studied body temperature changes during winter in semi-captive pichis by means of temperature dataloggers implanted subcutaneously. Our objective was to determine whether the pichi (Zaedyus pichiy), a small armadillo (Xenarthra, Dasypodidae) that inhabits arid and semi-arid habitats in central and southern Argentina and Chile, enters shallow daily torpor or prolonged deep hibernation during winter when environmental temperature and food availability are low. Hibernation and daily torpor are physiological strategies to cope with energetic challenges that occur in many mammalian and avian taxa, but no reliable information exists about daily torpor or hibernation for any xenarthran.
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