The cactus wren is one of our favorite birds. It is a big wren, certainly bigger than any other of the wren family, and it is a bird that is always busy investigating and gathering. It also sounds the alarm when the roadrunner is nearby or when there is a snake lurking. Dan and I dutifully go out when we hear his special alarm call to see what the problem is and, if necessary, mitigate it.
A lot of the cactus wren's time is spent building nests. They are not always nests in the traditional "let's raise some kids" sense, it is a bird that likes options. Some of the nests are used as roosts and perhaps a number of them are built as decoys?
The building happens very quickly: the project is completed in a day or so. I know this because a cactus wren decided that a pot of epiphyllums would be enhanced by a nest and for a week I removed nesting material every day. I have now given up, at least until Spring, and as long as he/she does not mind the nest getting wet every morning when I water plants.
There are also cactus wren nests in the sotol and in the pear trees. Quite frankly there are cactus wren nests in every kind of tree around the house. And in the desert the preferred building site for a cactus wren nest is of course a cactus: all varieties of cholla, all of them very thorny.