April Species Spotlight: House Wren

House Wren (Troglodytes aedon)

Family Troglodytidae

When I stepped outside this morning, I heard something that I had been patiently awaiting over the past five months – the vivacious, rolling song of the House Wren.

The House Wren (Troglodytes aedon) has one of the widest breeding ranges of any songbird in the Western hemisphere. They nest anywhere from southern Canada to the southernmost tip of South America. During winter, the House Wren migrates away from our region to spend the colder months farther south. They are uniformly brown with barring on wings, tail, back, and flanks. The Carolina Wren (Thryothorus ludovicianus) is another common species in the region that can sometimes be confused with the House Wren. They can be easily separated based on the Carolina Wren’s pronounced, white eyestripe. They are also larger than the small, 4-5 inch long House Wrens.

This species makes up in sound what it may lack in appearance. Both males and females deliver astonishingly loud songs. Their vibrant warbles are perhaps one of the best recognized signs of spring. The males in particular are known for their intricate vocalizations. An astounding 130 different song types have been recorded from this species. Single males are robust songsters and have the stamina to sing for up to 10 minutes at a time. Around the time of copulation, a mated male may give a “whispering song” that is performed with his bill closed. This quiet song likely functions to maintain communication with the female, yet does not disclose her location to competing males.

Perhaps the most charming characteristic of this species is its ebullient personality. The seemingly endless energy of the House Wren likens that of a child on a sugar high. This bird can be seen hopping through brush, leaves, and understory in the blink of an eye. These busy insectivores are constantly searching for enough food to maintain their metabolism. Mollusks are also on the menu – the calcium from snail shells is important to their health.

For such a tiny bird, they pack a serious punch. House Wrens are aggressive cavity nesters. They sometimes pillage the occupied nests of other birds if they find that site to be desirable for their own nest. They are known to puncture and remove eggs and even kill adult Tree Swallows, Eastern Bluebirds, and Prothonotary Warblers. Aggressive conspecific competition is not uncommon. Single males will try to steal the females away from their mate. If the new male out-competes the other for the female, he will remove the original eggs or young.

Watching House Wrens contrive their nests is endlessly fascinating. The male masterfully jams long twigs into the small nest box opening. At first glance, the inside of the nest box looks like a haphazard mass of sticks. Upon closer inspection, a small cup lined with soft materials can be found within the mound of twigs. Males typically construct multiple nests to impress a female. If she approves, she lays anywhere from 3 to 10 white eggs covered in reddish brown speckles in the nest of her choice. Adults will sometimes carry spider egg sacs into the nest box. These are not intended to be a snack for the growing young; rather, the spiders are used as built-in pest control – they eat pesky nest mites.

Brushy, tangly habitat near clearings, open woodlands, trees, shrubs, or edges makes for a great nesting site. City parks, residential neighborhoods, and scattered patches of vegetation are the perfect place to find this bird. Both naturally existing cavities and man-made nest boxes are used by the wren. To encourage House Wren nesting in your yard, consider adding a brush pile or making a nest box. Keeping cats indoors will also increase the success of any nesting bird near your home.

As the season progresses, migrant birds arriving for the breeding season begin filling the fresh spring air with sound. Keep an ear out for the exuberant song and animated activity of your local House Wrens.