Fig. 1. (A) Dive patterns, (B) heart rate and (C) abdominal temperature of a male great cormorant on Christmas Day 2002 in West Greenland (i.e. during the polar night). Heart rate is maximum when the bird is at the water surface (1), but decreases sharply during dives (2). Sustained heart rates >200 beats min^-1 in the absence of diving activity occur during flight (3). Note that the abdominal temperature of the bird decreases gradually during the dive bout (T), to reach a minimum after completion of the dive series (4). This short-term temperature drop is probably linked to combined effects of diving in cold water and of ingesting cold fish.