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 house . [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]
The great spotted woodpecker is a medium-sized woodpecker with pied black and white plumage and a red patch on the lower belly. Males and young birds also have red markings on the neck or head. This species is found across the Palearctic including parts of North Africa. Across most of its range it is resident, but in the north some will migrate if the conifer cone crop fails. Some individuals have a tendency to wander, leading to the recolonisation of Ireland in the first decade of the 21st century and to vagrancy to North America. Great spotted woodpeckers chisel into trees to find food or excavate nest holes, and also drum for contact and territorial advertisement; like other woodpeckers, they have anatomical adaptations to manage the physical stresses from the hammering action. This species is similar to the Syrian woodpecker.
Woodpeckers are part of the bird family Picidae, which also includes the piculets, wrynecks and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar and the extreme polar regions. Most species live in forests or woodland habitats, although a few species are known that live in treeless areas, such as rocky hillsides and deserts, and the Gila woodpecker specialises in exploiting cacti.
The Sonoran Desert is a hot desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States. It is the hottest desert in both Mexico and the United States. It has an area of 260,000 square kilometers (100,000 sq mi).
The northern flicker or common flicker is a medium-sized bird of the woodpecker family. It is native to most of North America, parts of Central America, Cuba, and the Cayman Islands, and is one of the few woodpecker species that migrate. Over 100 common names for the northern flicker are known, including yellowhammer, clape, gaffer woodpecker, harry-wicket, heigh-ho, wake-up, walk-up, wick-up, yarrup, and gawker bird. Many of these names derive from attempts to imitate some of its calls. It is the state bird of Alabama.
The yellow-bellied sapsucker is a medium-sized woodpecker that breeds in Canada and the northeastern United States.
The acorn woodpecker is a medium-sized woodpecker, 21 cm (8.3 in) long, with an average weight of 85 g (3.0 oz).
The red-bellied woodpecker is a medium-sized woodpecker of the family Picidae. It breeds mainly in the eastern United States, ranging as far south as Florida and as far north as Canada. Though it has a vivid orange-red crown and nape it is not to be confused with the red-headed woodpecker, a separate species of woodpecker in the same genus with an entirely red head and neck that sports a solid black back and white belly. The red-bellied earns its name from the pale reddish blush of its lower underside.
The red-naped sapsucker is a medium-sized North American woodpecker. Long thought to be a subspecies of the yellow-bellied sapsucker, it is now known to be a distinct species.
The red-cockaded woodpecker is a woodpecker endemic to the southeastern United States.
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian blackbird, or the elaborately woven hanging nest of the Montezuma oropendola or the village weaver—that is too restrictive a definition. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel. The smallest bird nests are those of some hummingbirds, tiny cups which can be a mere 2 cm (0.8 in) across and 2–3 cm (0.8–1.2 in) high. At the other extreme, some nest mounds built by the dusky scrubfowl measure more than 11 m (36 ft) in diameter and stand nearly 5 m (16 ft) tall. The study of birds' nests is known as caliology.
Lucy's warbler is a small New World warbler found in North America. This species ranges includes southwestern United States and northwestern Mexico. It is one of only two warblers to nest in cavities.
The Gila woodpecker is a medium-sized woodpecker of the desert regions of the southwestern United States and western Mexico. In the U.S., they range through southeastern California, southern Nevada, Arizona, and New Mexico.
The gilded flicker is a large woodpecker of the Sonoran, Yuma, and eastern Colorado Desert regions of the southwestern United States and northwestern Mexico, including all of Baja California, except the extreme northwestern region. Yellow underwings distinguish the gilded flicker from the northern flicker found within the same region, which has red underwings.
Aridoamerica denotes an ecological region spanning Northern Mexico and the Southwestern United States, defined by the presence of the culturally significant staple foodstuff Phaseolus acutifolius, a drought-resistant bean. Its dry, arid climate and geography stand in contrast to the verdant Mesoamerica of present-day central Mexico into Central America to the south and east, and the higher, milder "island" of Oasisamerica to the north. Aridoamerica overlaps with both.
The Magellanic woodpecker is a species of large woodpecker found in southern Chile and southwestern Argentina; it is resident within its range. This species is the southernmost example of the genus Campephilus, which includes the famous ivory-billed woodpecker.
The Hispaniolan woodpecker is a medium-sized woodpecker endemic to the Caribbean island of Hispaniola.
The saguaro is a tree-like cactus species in the monotypic genus Carnegiea that can grow to be over 12 meters tall. It is native to the Sonoran Desert in Arizona, the Mexican state of Sonora, and the Whipple Mountains and Imperial County areas of California. The saguaro blossom is the state wildflower of Arizona. Its scientific name is given in honor of Andrew Carnegie. In 1994, Saguaro National Park, near Tucson, Arizona, was designated to help protect this species and its habitat.
Drosophila metlerri, commonly known as the Sonoran Desert fly, is a fly in the genus Drosophila. The species is found in North America and is most concentrated along the southern coast of California and in Mexico. D. mettleri are dependent on plant hosts, namely, the saguaro and cardon cacti. Thus, they are most prevalent in arid, desert conditions. It is able to detoxify chemicals found in the rotting liquid of cacti hosts, which allows it to use otherwise lethal soil as a nesting site.
Scar tissue that forms around nest cavities excavated in saguaro stems is later encountered among the remains of a dead saguaro as a hard, brown shell known as a "saguaro boot" because of its shape.
Both gilded flickers and Gila woodpeckers make these cavities for nesting but they often choose different locations on the cactus.
The marks signal "Here be larvae" to the bird, and as it excavates the insects, it also cuts away the diseased tissue. As the sap hardens, the cactus is healed, and the excavation becomes a convenient nesting site.
A nest hole is excavated in a tall saguaro cactus, about 9 feet from the top and 11 to 25 feet from the ground.