Thermoregulation and sleep: Effects of thermal stress on sleep patterns of Glaucous-winged gulls (Larus glaucescens)

1. 1. To determine effects of thermal stress on avian sleep patterns, incubating Glaucous-winged gulls were subjected to conditions of heat loss and heat gain via conduction from hollow copper eggs. 2. 2. Heated manipulations resulted in significant reductions in sleep and rest relative to controls, whereas cooled manipulations had little effect. 3. 3. The resilience of sleep to thermal stress is greater than that of rest. We suggest that the incompatability of sleep with conductive processes to off-load heat from the eggs is responsible in this case. 4. 4. Pant Sleep, the behaviour in which birds appear to maintain some the benefits of both sleep and panting, is not used as a thermoregulatory strategy, but may allow some sleep when under thermal loading.