What does my husband Dave have on his nose? It is a boot. A boot from a saguaro cactus. When birds like gila woodpeckers build nests in saguaros they chisel out holes in the cactus. The nest cavity is fairly deep so the baby birds will be hidden from view after they hatch. The saguaro creates a kind of hard callus around the wound created by the nest cavity. Since the bird has damaged it’s tissue the cactus must protect itself. So it secretes a resinous sap that, over time, hardens into a bark-like shell that prevents the cactus from losing fluid and also protects the nest hole by making it waterproof.
You can see a nest hole in this saguaro. When the saguaro dies and its soft outer flesh rots the hard callus remains behind in the shape of a boot. Long ago native Americans used these saguaro boots for storage containers.
We learned about saguaro boots on our visit this week to the Phoenix Desert Botanical Garden. I was lucky enough to get a couple of photos of a woodpecker at work building a nest in a saguaro cactus as we walked along the trails.
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