What Causes Holes In Saguaro Cactus

Holes in saguaro cactus are almost always caused by birds, primarily the Gila woodpecker and gilded flicker.
 
These birds don’t create holes in saguaro cactus for food, but instead they excavate nesting cavities inside the living tissue of the cactus.
 
When you spot holes in saguaro cactus, you are likely looking at an old nest that was carved out by one of these two woodpecker species.
 
In this post, we’ll explore exactly what causes holes in saguaro cactus, why these holes don’t kill the cactus, and what other animals might create or use these openings.
 
Let’s dig into the fascinating story behind these desert scars.
 

What Causes Holes in Saguaro Cactus?

The most common cause of holes in saguaro cactus is nesting activity by woodpeckers, but there are a few other culprits too.
 
Let’s break down each one so you know exactly what you’re seeing when you spot holes in saguaro cactus out in the desert.
 

1. Gila Woodpeckers Create Most Holes in Saguaro Cactus

Gila woodpeckers are the primary reason you see holes in saguaro cactus.
 
These birds carve out a cavity that’s about the size of a small fist, and they do this during the breeding season.
 
They choose a spot on the saguaro’s trunk or arms where the tissue is firm and healthy, not too watery or too dry.
 
A single Gila woodpecker pair will use the same hole in saguaro cactus for several years, returning each spring to raise a new brood.
 
The excavation process takes about two to three weeks, and the bird chisels away slowly with its strong beak.
 
This is why holes in saguaro cactus are almost always perfectly round and smooth on the inside.
 

2. Gilded Flickers Also Make Holes in Saguaro Cactus

Gilded flickers are larger than Gila woodpeckers, so their holes in saguaro cactus are noticeably bigger and deeper.
 
These birds prefer to nest high up on the main trunk of the saguaro, often near the top of an arm.
 
While gilded flickers create fewer nesting holes than Gila woodpeckers, the holes they make are still quite common across the Sonoran Desert.
 
You can tell a flicker hole from a woodpecker hole because it’s wider and sometimes has a more oval shape.
 
Both species are responsible for the vast majority of holes in saguaro cactus that you’ll ever encounter.
 

3. Rot and Disease Can Expand Existing Holes in Saguaro Cactus

Once a bird creates an initial hole in saguaro cactus, bacteria and fungi can sometimes move in and enlarge it.
 
The cactus responds by forming a hard callus tissue called “bark” around the edge of the wound.
 
In most cases, this callus seals the hole in saguaro cactus and prevents the rot from spreading deep into the plant.
 
However, if the hole is damaged further by weather or animals, rot can set in and create a larger cavity over time.
 
This is why some older holes in saguaro cactus look much bigger than the original bird excavation.
 

4. Other Animals That Use Existing Holes in Saguaro Cactus

After the woodpeckers abandon their nest, many other desert creatures move into the holes in saguaro cactus.
 
Elf owls, the smallest owls in the world, are famous for nesting inside old woodpecker holes in saguaro cactus.
 
Purple martins, finches, and even some snakes will also use these cavities for shelter or hunting.
 
These animals don’t create new holes in saguaro cactus, but they absolutely depend on the ones that already exist.
 
So when you see a hole in saguaro cactus, it could be a vacant apartment or someone’s current home.
 

How the Saguaro Cactus Survives Having Holes

You might wonder how a cactus stays alive after a bird carves a hole right into its flesh.
 
The saguaro has an amazing ability to seal off wounds, so holes in saguaro cactus rarely kill the plant.
 
Let’s look at the survival mechanisms that keep these giants standing tall despite their holes.
 

Callus Tissue Forms a Protective Shield

When a woodpecker starts carving, the cactus immediately begins producing callus tissue around the cut.
 
This tissue is tough, woody, and waterproof, and it hardens into a protective ring within a few weeks.
 
The callus acts like scar tissue, isolating the hole in saguaro cactus from the healthy water-storing flesh inside.
 
Over the years, this callus becomes incredibly strong, often as hard as wood itself.
 
That’s why you can see old holes in saguaro cactus that have been there for decades, and the cactus is still thriving.
 

Water Loss Is Minimal Through the Hole

A hole in saguaro cactus might seem like an open wound that would leak precious water, but that’s not the case.
 
The callus seals the hole so effectively that very little moisture escapes.
 
The cactus stores water in its outer flesh, not in the woody skeleton where the bird carves.
 
So the hole in saguaro cactus doesn’t puncture the main water storage chambers.
 
This is why a saguaro can live for 150 to 200 years even with multiple nesting holes.
 

The Life Cycle of a Hole in Saguaro Cactus

Every hole in saguaro cactus tells a story, and that story usually begins in spring and ends in winter.
 
Let’s follow the timeline of how a hole is created and used.
 

Spring Excavation

In March and April, woodpeckers begin inspecting potential saguaro nests.
 
They peck at different spots and can smell moisture, choosing a spot that feels firm enough to hold a cavity.
 
Once chosen, the bird spends weeks carving out the hole in saguaro cactus.
 

Summer Nesting

By late spring, the hole in saguaro cactus is ready for eggs.
 
The woodpecker lays two to four eggs inside, and the chicks hatch in about two weeks.
 
The parents feed the chicks inside the safety of the cactus cavity until they fledge in early summer.
 

Fall and Winter Occupancy

After the nesting season, the woodpeckers may abandon the hole in saguaro cactus.
 
Then, other birds like elf owls move in for the cooler months.
 
The hole stays occupied by a series of tenants throughout its life, which can be up to 30 years.
 

What Happens After the Hole Is Abandoned Permanently

Eventually, the hole in saguaro cactus becomes too deep or damaged for nesting.
 
At that point, the callus continues to grow and may slowly close the opening over many years.
 
Some holes in saguaro cactus never close completely, but they remain as harmless scars on the plant’s surface.
 
In rare cases, the entire arm with the hole may break off during a storm, but the main trunk survives.
 

So, What Causes Holes in Saguaro Cactus?

Holes in saguaro cactus are caused by birds, not by disease or bugs acting alone.
 
Gila woodpeckers and gilded flickers are the primary creators of holes in saguaro cactus, and they make these holes strictly for nesting.
 
The saguaro cactus survives these holes thanks to its tough callus tissue and its ability to seal off the wound.
 
Other animals like elf owls and purple martins then move into the abandoned holes in saguaro cactus, completing the cycle.
 
So next time you’re hiking in the desert and spot holes in saguaro cactus, you’ll know it’s a sign of life, not decay.
 
Hope this post has helped you understand what causes holes in saguaro cactus and why these desert giants can live with them so well.