I owe this one to my sister-in-law!  While strolling along on a beautiful hiking trail we decided to take our shoes off and dip our feet in a small creek.  My sister-in-law waded over to a little sandy spot under an alder tree where she soon experienced a female rufous dive-bombing her with a lecturing defense call.  Because of her behaviour we knew we must be close to her nest, which was neatly tucked under the canopy of the alder tree.  The average size of a rufous hummingbird nest is about 2 inches in diameter.  They are woven from plant fibers and binded together with spider webs for both strength and so the nest can stretch as the babies grow.