Fig. 2
Effects of huddling and cold on body temperature. a Infrared images of representative CH (cold huddling), CS (cold separated), WH (warm huddling), and WS (warm separated) voles (n = 7–8/group) measured in the second week of acclimation. b Tsurface (surface body temperature) by infrared temperature readings from the eye (maximum temperature, Tm), around individual animals, or the entire groups (perimeter temperature, Tp) and between two animals only in huddling groups (contact temperature, Tc). c Tcore (core body temperature) in the first 2 days of exposure (n = 4–5) in huddling and separated Brandt’s voles at warm and cold Ta. The gray area indicated scotophase (20:00–04:00). d, e Average daily Tcore (n = 4–5) in huddling and separated Brandt’s voles at warm and cold Ta. *** P < 0.001