Saguaro boot
A saguaro boot is the hard shell of callus tissue, heavily impregnated with lignin, that a saguaro cactus (Carnegiea gigantea) creates to protect the wound created by a bird's nesting hole.[1] The bird pecks through the cactus skin, then excavates downward to hollow out a space for its nest.[2] When the saguaro dies, its soft flesh rots, but its woody infrastructure lasts much longer. So does the hollowed-out callus whose roughly boot-like shape gives it the name of "saguaro boot."[3]
Several different kinds of birds create nest holes in saguaro cactus. The Gila woodpecker (Melanerpes uropygialis) creates small holes (about 5 cm across) at midlevel on the cactus, where the ribs are far apart,[4] feeding on larvae under the cactus skin.[5] The larger gilded flicker (Colaptes chrysoides) drills bigger holes higher up,[6] where ribs are close together, because its beak is strong enough to break through rib tissue.[4]
The saguaro responds to the bird's damaging its tissue by secreting 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.[4] The bird's nesting hole requires not only the bird's making a hole but also the cactus's lining the hole - it is not ready for use as a nest until a year after its creation.[4] Many saguaros are home to multiple nests; if birds excavate adjoining hollows, a saguaro boot may be formed with more than one opening.
Native Americans of the Seri group used saguaro boots to store or carry water.[7] It is now illegal to collect saguaro boots from the wild in Arizona.[8]
Some desert moth caterpillars also make tunnels inside saguaro cactus. The resulting dried callus that forms around their tunnels has a flattened disk structure where the caterpillar exits instead of the larger hole seen on a saguaro boot.[1]
References
<templatestyles src="Reflist/styles.css" />
Cite error: Invalid <references> tag; parameter "group" is allowed only.
<references />, or <references group="..." />Gallery
-
SaguaroBoot 2.jpg
Saguaro boot with US quarter to show scale
-
SaguaroBoot 1.jpg
Slightly different viewpoint of same saguaro boot
-
DBG SaguaroBoot.jpg
Saguaro boot with saguaro. Boot toe should point down, not up.
-
DBG SaguaroBoot3holes.jpg
Three nest-holes united into one saguaro boot
-
Dead saguaro1.jpg
The bare wooden ribs of a dead saguaro
-
Saguaro1.JPG
Saguaro with nest holes
-
Gilded Flicker (Colaptes chrysoides) by nest hole in saguaro cactus.jpg
Gilded flicker by nest hole in saguaro cactus
-
Melanerpes uropygialis Tucson AZ.jpg
Gila woodpecker on cactus
-
SaguaroInsectDamage.JPG
Saguaro with dime-sized rosette from caterpillar exit hole
-
HoleLivingSaquaro.JPG
Close-up of living saguaro with hole, wound-response lignin, quarter shown for scale
-
HoleLivingSaguaro2.jpg
Longer view of living saguaro with hole seen in previous close-up
-
Jefftimscactus.jpg
Looking up a saguaro
- ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 4.0 4.1 4.2 4.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
