This week’s Bird of the Week, compliments of the Weminuche Audubon Society and Audubon Rockies, is the marsh wren.
When you’re out for a winter stroll on the Riverwalk, stop awhile near the warm water pond at the end of the 6th Street bridge and you may hear the song of this bird. Wrens as a group are known for singing remarkably big songs for their small sizes. Analysis of birdsong ranks the male marsh wren among the North American songsters considered most impressive.
Don’t expect a melodic sound from this wren, whose song is described as rapid-fire gurgling and trilling, buzzy and sewing-machine like. Instead, he is admired for the 150 or more songs that he learns and sings in defense of territory and to attract his mates. In some populations, around 50 percent of the males are polygynous, mating with two or more females.
Roger Tory Peterson, who published the first modern field guide for birds, described this bird as “the wren of the cattail marsh,” but other marsh plants like sedges, bulrushes and wild rice will also do as long as they are tall and dense. Marsh wrens can be secretive and well-camouflaged, much easier to hear than spot.
Within this habitat, they are constantly on the move, foraging on stems, leaves and the water’s surface for any accessible invertebrate — spiders, bees, beetles and aquatic larvae. Males are prodigious nest builders, suspending between stalks a woven ball of vegetation with a hollowed-out interior and small entry hole. Additionally, he will build six or more dummy nests within his territory that may serve as decoys to deter predators looking to raid a nest.
This tiny bird is rusty brown above with black and white streaks down its back. It typically holds its short, barred tail straight up. It has a pale, unstreaked underside and a pale eyebrow streak. If you are hoping to spot one, be prepared to check out any rapid movement within the marsh for a brief look before it disappears again.