This is the final period (ko) of the "White Dew on Grass" solar term (sekki) by which farmers marked the seasons in olden days, as imported from China. Barn Swallows head south at this time to avoid the Northern winter. They can fly 8 to 12 hours consecutively without resting as they island hop across Okinawa, Taiwan, SE China and Hong Kong on their way to Vietnam, Thailand and other southern countries. They feed on insects to replenish their energy and roost on tall grass as they make their way south, returning to Japan in the spring to rise two or three broods per year in their mud nests.
by KyotoGaijin