When my husband built a covered porch on the front of our house, he anticipated that someday a bird might try to build a nest there. So he built the top of the corner post on a slant. Later we laughed smugly when we saw robins trying their best to claim squatting rights to a new home. Piles of grass on the porch revealed their wasted efforts. But after 2 days of steady rain, we saw that a nest had indeed appeared in the very spot we thought was impossible. Because of the rain, Mrs. Robin was able to mix up a batch of mud mortar. Weaving it with twigs and grass, our determined feathered friend had built herself a new nest. She had persevered.