EPOW - Ecology Picture of the Week

Cholla of the Sonora, Part 2

Nest of Cactus Wren (Campylorhynchus brunneicapillus), Family Troglodytidae
Cholla Cactus (Cylindropuntia [prev. Opuntia] cf. bigelovii), Family Cactaceae
Sonora, Mexico

Explanation:  Last episode, we encountered the "jumping cholla" cactus of the Sonoran Desert of southwest U.S. and northwest Mexico.  This week, let's explore its relationship with wildlife of the desert ecosystem.  

The star of this week's main photo is a nest of the appropriately-named Cactus Wren.  This is a bird species found widely in the Sonoran as well as Chihuahuan and Mojave Deserts and some adjacent environments.  They typically nest in plants of the desert, including the very protective cholla.  

Here is a cactus wren nest with a side entrance.

The nests are built by both male and female cactus wrens.  The cactus spines and the narrow nest entrance hole contribute to protection from predators.  

Cactus Wren males defend their nests and territories vigorously.

But stands of cholla cactus and other cacti species also provide key habitats for other desert denizens.  

For example, Cholla also offers protective nesting for other bird species, such as House Finch (Haemorhous mexicanus).  

Desert woodrats (Neotoma lepida) inhabit areas with dense cactus groupings, possibly because areas of dense cacti also provide other resources needed by the rodents, such as food, water, predator escape environments, and materials for building their dens (Brown et al. 1972).  

Fruits of chollas are taken by various wildlife species, including adult Sonoran pronghorns (Antilocapra americana).

So step carefully but savor the value and roles of this most interesting plant of the desert.
  
     

Information:
     Brown, J.H., G.A. Lieberman, and W.F. Dengler.  1972.  Woodrats and cholla: dependence of a small mammal population on the density of cacti.  Ecology 53(2):310-313.