They also were the home of migrating water birds. Flowers such as white and blue lotus were grown in the ponds for decoration and for ceremonies, and papyrus was known to grow at Deir el-Bahri. Later, during the Persian occupation of Egypt, the pink lotus was introduced. Shade was an important feature of the garden, provided by trees and by grapevines supported between columns. Describing these gardens, Shaw and Nicholson wrote, "The overall effect would have been one. of cool shade , heavy with the fragrance of the flowers and the trees. Gardens are therefore one of the most frequent settings of Egyptian romantic tales." Gardening in ancient Egypt was very hard work; gardens required constant irrigation, with water carried or lifted by hand, weeding, and tending, including the artificial propagation of date palms, which required great skill. Great effort was also needed to keep birds from eating the crops. Ingenious traps were set to catch the invading birds.