1. The surfacing frequency of X. laevis increased with temperature from 1 to 6 h - 1 between 5 and 20°C, either by day or night, but was unchanged between 20 and 25°C.2. The duration of individual visits to the surface was relatively short (10-40 s) and unaffected by temperature below 20°C during the day but increased markedly to over an hour when temperature was reduced from 20 to 5°C during the night. The duration of each visit increased when temperature was raised from 20 to 25°C during the day or night.3. Consequently, the proportion of total time spent on the water surface by the toads increased with temperature (2-12%) during the day; whereas during the night, total time at the surface was highest at 5°C (50%), lowest at 20°C (14%) and higher at 25°C (30%).4. The brief visits to the water surface during the day are probably driven by oxygen demand or the accumulation of CO 2 . At night, when predation pressures may be reduced, the toads spend more time at the surface.