Saguaro cacti are home to many critters and the bird nests, surprisingly, do not harm the Saguaro. Cactus Wrens and Gila Woodpeckers often make their home in Saguaros.
I used the term crested but the term used to describe the undulating folds in the cactus instead of the typical arms being produced is Fasciation. Fasciation is caused by mutation of cells, infection or chemical or mechanical damage to a plant. In some plants it is an inherited trait. Seeing these crested saguaros is rare.
Compare today's photo with the photo of a normal Saguaro, which I previously posted.