The Saguaro: A Keystone Species

Here are 10 ways the saguaro functions as a keystone species:

1. Provides critical nesting sites – Gila woodpeckers and gilded flickers excavate cavities in saguaros, which are later used by elf owls, screech owls, kestrels, purple martins, and other birds.

2. Supports a wide range of wildlife – More than 100 animal species use saguaros for nesting, roosting, hunting perches, or shelter at some point in their lives.

3. Major food source through fruit – Saguaro fruit and seeds are eaten by birds, bats, insects, coyotes, javelinas, tortoises, and other mammals, especially during the harsh early summer.

4. Night-blooming flowers sustain pollinators – Their large white flowers feed lesser long-nosed bats, bees, moths, and birds, making saguaros essential to regional pollination networks.

5. Times food availability to the hottest season – Saguaro fruits ripen in late spring and early summer, when few other desert foods are available, helping many species survive seasonal bottlenecks.

6. Creates vertical structure in the desert – As the tallest plants in the Sonoran Desert, saguaros provide hunting perches and vantage points for hawks, owls, and ravens.

7. Regulates microclimates – Their shade lowers ground temperatures around their base, benefiting seedlings, insects, reptiles, and small mammals.

8. Facilitates plant recruitment – Young saguaros often germinate under “nurse plants,” but mature saguaros themselves later act as nurse structures for other desert plants.

9. Stabilizes desert soils – Extensive root systems help reduce erosion and increase water absorption during brief desert rains.

10. Cultural keystone role for humans – For Indigenous peoples such as the Tohono O’odham, saguaros provide food, materials, and cultural traditions that have shaped human–desert relationships for centuries.

Because so many Sonoran Desert species depend on saguaros directly or indirectly, their loss would trigger cascading ecological effects, clearly marking the saguaro as a keystone species.