Saguaro cacti (Sa-WAR-oh) provide food and homes for a large number of desert animals. You wouldn’t think so–the cactus has big thorns, are tall (40-60 feet), and live for 150 years. Doesn’t sound like a friendly place to set up housekeeping.
Saguaros attract Gila Woodpeckers. With their tough beaks, they drill holes in the low- to middle areas of the cactus, between the ribs. You can see one in the center of the cactus in the photo on the right.
A saguaro is not hollow. It’s made up of tough, long ribs and woody structure. This is what a cross section of a dead saguaro looks like:
Cross-section of a saguaro, showing the woody interior and the ribs that hold it upright.
A bird has to be pretty persistent to drill through the outer skin into the cactus. When the bird breaks through and hollows out a space big enough for a nest, the bird abandons the cactus. The cactus protects itself by secreting a material that hardens into a waterproof lining for next year’s nest.
Hand holding a saguaro boot. © Take a Hike, Arizona.
The lining is called a boot, and the Native American tribes used the boots to carry water and to use as waterproof shoes. The next year, when the boot is firm, Gila Woodpeckers will build a nest. After the woodpeckers abandon the nest, elf owls, screech owls, purple martins and starlings will take turns. There is a strict pecking order (yeah, I said that) of birds.
Higher up the saguaro, the Gilded Woodpecker can drill through the harder ribs. They build nests underneath the arms of a saguaro, which protects the entrance to the nest. It can also provide important shade in a landscape that rarely has overcast days.
In late April the saguaro sets flower buds. Bats, moths, and small birds pollinate the flowers.
Once the fruit forms–at the top of the arms of the cactus–it provides necessary liquid and food for birds, and the chunks that are spilled and drop provide food and liquid for rabbits, desert squirrels and rats.
A saguaro grows slowly. A 10-year old plant may be only a few inches tall. While they are still small, the cactus is food for bighorn sheep and mule deer.
Those that survive to the 30-foot mark or higher and develop arms (at around 75 years of age) provide the support for the large platform nests of Red-Tail and Harris Hawks. Once the nests are built, Great Horned owls and other large hawks might battle for the nest. Harris Hawks are team-hunters and they get the first call on the nest. Take on a Harris Hawk, and you have the whole family to deal with.
Saguaros are fascinating and do a lot more than stand around and look tall.
—Quinn McDonald is a naturalist and writer who lives in the Sonoran Desert.