Cactus wrens makes their desert nests in Big Bend
What a cactus wren lacks in good looks and pretty songs, it makes up for in home construction.
The home is both a nest and a place to live throughout the year. That’s critical for a bird living in the ruggedly arid Big Bend National Park, where my wife, Kathy, and I spent our vacation.
We saw several cactus wren nests ensconced in thorny cacti where no sane coyote, fox, or bear would poke its nose.
Looking like an orbicular bunker made from scraggly twigs, each nest has an entrance hole to the side and a domed roof that shades chicks from intense sunlight. The domed roof would also trap the body heat of roosting birds to keep them warm during winter and even during chilly summer nights in the Chisos Mountains.
Despite a secure nest construction, eggs and chicks are fair game for predators. Greater roadrunners are adept at pillaging lizards and birds out of cactus plants. Raptors, like zonetailed hawks, will plunder the nest, as will long, lithe whipsnakes, one of which wove its elongated body through the branches of a gray oak outside our cabin. Creepy!
Male and female cactus wrens first build a breeding nest. The male then builds multiple alternate nests several yards around the original nest where the female incubates eggs. Secondary nests are used as roosting sites for the male and later for the female.
Ancillary nests may also serve as faux nests to distract predators. We found several alternate nests among clusters of cholla cacti as a presumably male wren squawked and flitted among the faux nests to distract us from the nest with chicks.
Both males and females look the same and are by no means as petite as Carolina wrens here at home. Cactus wrens are robust, strong-legged birds the size of
cardinals with long, slightly decurved beaks similar in shape to a Carolina wren’s beak but stouter.
Their plumage matches the arid terrain, with brown backs streaked in white, a bold white eyebrow, a white throat speckled with dense dark spots, and a buffy belly marked by dark streaks. Their long, rounded tails display black-and-white bars.
The male sings loudly in a gravelly voiced song beginning at daybreak and sounding like “charrr …charrr … charrrr” that builds in tempo to a crescendo. His song is joined by other nearby males, creating a cacophonous chorus across a desert or mountain canyon.