Window on Nature
By Lowell and Kaye Christie, F47246
These desert-dwellers may not sound particularly tuneful, but they’re quite content making their home in the arid environment.
Out in the desert, long before the sun peeks over the horizon, the sounds of birds enter the open vent in our motorhome, providing our wake-up call as the avian community greets the new day. We try to identify each new melody as it appears, waiting for the familiar voice, gradually leaving sleep behind. At least until we hear the noise coming from the cholla cactus right next to the coach.
Fortunately, the local cactus wren often sleeps a bit later than the more sweet-sounding inhabitants of the desert. You would never consider its song musical. The calls usually consist of fast notes delivered in a monotone “chur chur chur.” There are regional versions, however, so you might hear a “growl,” “buzz,” or “dzip” instead.
Someone described a cactus wren’s call as similar to the grinding sound of a car engine trying to turn over on a cold morning. That might be a bit harsh, but in Spanish the bird is called matraca del desierto. Matraca means a wooden rattle. Maybe “wooden rattle of the desert” would be a good description.
As frequent desert travelers, we’ve often had cactus wrens as campground neighbors. Curious birds, they’re quick to investigate anything new in their territory. Should you leave your coach doors or windows open, don’t be surprised if one hops in and makes itself comfortable. They’ll snoop into every nook and cranny, whether looking for an insect snack or just following their inquisitive nature.
Cactus wrens are dependable desert companions, as they don’t migrate. They prefer hanging out in the same habitat year-round. Their range includes southern Nevada and Utah; west Texas; and west through New Mexico, Arizona, and southern California.
As for altitude, you can find them as high as 6,000 feet in New Mexico, but only as high as 4,000 feet in Arizona. Each area has its arid regions, supporting the yucca, mesquite, and/or cactus necessary, since cactus wrens usually insist upon building their nests in prickly places. Being surrounded by cactus spines helps keep the offspring safe from predators.
Since the nests have such strong natural defenses (the vicious cholla cactus is a favorite nest site), the cactus wren doesn’t bother much with camouflage. The nest is large and easy to locate, and unlike most bird nests, it is entirely enclosed except for a tube-like entrance.
Male and female cactus wrens work together constructing the first nest. After choosing a nice prickly setting, they begin gathering dry grasses to use in building the football-shaped interior walls. Sometimes the sides are decorated with bits of paper or cloth woven in with the natural materials. Next, the birds line the walls with feathers or other soft, cuddly substances.
The most common linings are the feathers of another desert bird, one of the abundant local species of quail. Some years ago biologists examining cactus wren nests in Sonora, Mexico, discovered the feathers of a species closely related to quail, the masked bobwhite. Until that time this bird was thought to be extinct, but after finding the feathers, a search turned up small populations of the masked bobwhite still in existence.
After the basic cactus wren nest is completed, the side entrance is built. This allows the birds to gain access, but excludes most would-be predators. Without a top opening, the nestlings won’t be visible to raptors, and although the spines of the nesting area keep out all but the most persistent of ground creatures, sometimes the slender coachwhip snake and whipsnake manage to get through the defenses.
Cactus wrens are compulsive builders, constructing as many as a half-dozen nests a season across their territory. But that doesn’t mean the male wren has a harem of females, each tending to its own eggs and young. A cactus wren couple forms a permanent pair bond, defending its territory year-round. The additional nests are often unlined, and are used as roosts for the growing family. Some of them may be used for additional broods later in the season.
The female lays her eggs and then incubates them for a little more than two weeks. The expectant father isn’t goofing off; he just keeps busy creating more nests. He’ll be back, though, as both parents tend to their hatchlings’ needs. After the young fledge (leave the nest), they’ll stay with their parents for another month or so, learning how to find food and stay out of trouble.
Unlike other North American wrens, the cactus wren is huge. It’s the largest wren in the United States, ranging from 7 to 9 inches in length. Its coloration and behavior also are different.
Most wrens wear basic brown. In contrast, a cactus wren has solid brown only on the top of its head. The rest of its body is clothed in patterns. A distinctive white stripe over the eyes separates the brown above from the black-and-white lines below. In contrast, on the bird’s belly and sides, you’ll see spots rather than stripes.
Some other differences make cactus wrens easy to identify. For one, it doesn’t always hold its tail cocked (pointing up) as most other wrens do. Another major difference is that this bird is easily heard and seen, rather than being reclusive and timid. That makes it easy to observe.
This wren species forages for food on the ground, snatching ants, beetles, grasshoppers, and wasps, along with tiny fruits and seeds. Given the chance, it will grab a small frog or lizard, but the cactus wren is so well adapted to desert life that, even without them, it will get along nicely with only the water in its buggy diet. Standing water is rarely used, even after a summer shower.
During the summer months the cactus wren starts its day looking for food in the open, but as the day gets warmer it continues its search in shady areas. In the hottest weather it acts like all the other desert creatures, waiting for the sun to drop in the western sky.
The cactus wren is usually the first bird we see when pulling into a desert campground. And, musical or not, to us its sound is the voice of the desert