 A field study late in the Florida nesting season revealed that on an average day , adult American white ibis spent 10 @.@ 25 hours looking for food , 0 @.@ 75 hours flying , 13 hours resting , roosting , and attending to their nests . Much of the time roosting is spent preening , biting and working their feathers with their long bills , as well as rubbing the oil glands on the sides of their heads on back plumage . American white ibis generally only preen themselves , not engaging in allopreening unless part of courtship behavior . Bathing often takes place before preening ; ibis squat in water 5 – 20 cm ( 2 @.@ 0 – 7 @.@ 9 in ) deep and flick water over themselves with each wing in succession . Hundreds of birds may bathe together around the time of courtship . 
