Fig. 1. Daily body temperatures T_b (means ± S.D.) of Galapagos marine iguanas measured in the field by radiotelemetry during the summers of 1991/92 and 1992/93. The data were collected every 15 min and are from 27 animals in 91/92 and 10 animals in 92/93. The transmitters were implanted for 14-81 days (M. Wikelski and F. Trillmich, unpublished data).