 Its head sometimes resembles that of a rain deity; at other times, it is more like that of a bird of prey, perhaps the laughing falcon believed to be a harbinger of rain.The wings are repeatedly inscribed with the signs for "daylight" and "night", suggesting that the bird's flight could represent the unfolding of time.The San Bartolo murals have a Principal Bird Deity seated on top of each of four world trees, recalling the four world trees (together with a fifth, central tree) which, according to some of the early-colonial Chilam Balam books, were re-erected after the collapse of the sky.