Survival of newborn ground squirrels after supercooling or freezing

Abstract

Six of seven 2-day-old ground squirrels survived without any harmful consequences 11 hr supercooling to body temperatures of –3 to –4 C. Longer exposure at the same body temperature was not followed by survival. Of 12 ground squirrels which were kept at stabilized body temperatures of –6 and –8 C for 5 hr, 10 animals survived. Electrical activity of the heart was not detectable when the body temperature of ground squirrels was below –2 C. Immersion of newborn ground squirrels in –35 C alcohol-dry-ice mixture caused their bodies to freeze after 15–20 sec, suddenly turning white and rigid. Ground squirrels survived the freezing which lasted less than 2 min. At the end of 2 min immersion the esophageal temperature of cooled animals was –10 to –15 C.