In the early 1900s, the House Wren, Troglodytes aedon, began to capture the attention of Althea Sherman, an artist and budding ornithologist in Iowa. Initially charmed by their presence in her backyard, Sherman observed these opportunistic nesters readily occupying birdhouses she provided. Over several years, her property became home to about 10 pairs of House Wrens, each successfully raising at least five chicks per season. Sherman diligently documented their lives, from their social interactions to their parental challenges. However, her admiration soon turned to dismay as she witnessed what she perceived as destructive behavior.
Sherman’s firsthand observations led her to describe the House Wren with increasingly harsh terms. She documented an instance where a wren invaded a Phoebe nest and removed two eggs, an act she deemed “evil.” Later, she witnessed a wren puncturing a Black-billed Cuckoo egg, calling the bird a “frightful devil.” This led Sherman to launch a campaign against the House Wren, publishing her findings in scientific journals and urging fellow ornithologists and bird enthusiasts to acknowledge the bird’s “criminal” nature and cease promoting nest boxes for them. [cite:0, cite:1]
At the time, some in the ornithological community dismissed Sherman’s views as overly emotional. She, in turn, argued that they were the ones blinded by affection for the “little brown birds,” unable to see their perceived malice. Sherman wrote in The Wilson Bulletin in 1925, “They act precisely like the parents of vicious children, refusing to believe the evil things their darlings do.” [cite:0, cite:2]
Indeed, subsequent studies over the past century have corroborated Sherman’s observations regarding the House Wren’s behavior. Wrens have been documented puncturing the eggs of various species, including bluebirds, woodpeckers, nuthatches, sparrows, chickadees, swallows, Bobolinks, and warblers, and have been known to take over their nests. This behavior aligns with Sherman’s characterization of the House Wren as a “felon, criminal, demon, and devil.”
However, a deeper examination of the House Wren’s behavior reveals a more complex ecological reality, far removed from human moral judgments. The very name Troglodytes aedon, translating to “crevice-dwelling nightingale,” carries a mythological connection to Aëdon, a queen who, in Greek myth, accidentally killed her own child and was transformed into a nightingale. This etymological link to infanticide highlights how readily humans project their moral codes onto the natural world.
Unlike human infanticide, the House Wren’s actions are driven by the fundamental instinct for survival and reproduction in a highly competitive environment. For cavity-nesting birds like the House Wren, securing a nesting site is paramount. When suitable vacant cavities are scarce, they resort to behaviors that ensure their own species’ continuation.
Evolutionary pressures rarely reward patience. House Wrens exhibit fierce impatience, often with complex mating strategies. A male may attract a second mate to a territory while his primary mate is still incubating, or he might seek out females in neighboring territories, sometimes destroying existing eggs or young to encourage the female to lay new eggs—his own. In cases where a male lacks territory, he may forcefully seize one, driving out the resident male, claiming his mate, and eliminating her offspring to start anew. This fierce competitiveness is a trait passed down to their numerous offspring, contributing to their evolutionary success.
The reasons behind the House Wren’s predation on the eggs and young of other species, particularly non-cavity nesters, are still debated among researchers. Some suggest it may reduce competition for food resources. Alternatively, there might simply be no evolutionary disadvantage for the House Wren in eliminating potential competitors, regardless of species.
While this behavior may appear brutal from a human perspective, the prominent ornithologist Witmer Stone, who generally agreed with Sherman on managing nest box populations, offered a different viewpoint. He noted that “The Wren is no more of a ‘felon’ for destroying the nest of a Bluebird than is a Flicker for destroying a nest of ants.” This perspective frames the wren’s actions within the broader context of interspecies competition and the natural order, rather than judging them by human ethical standards.
Despite Sherman’s dedicated crusade, which even extended to disinheriting the birds from her will, the House Wren remains one of North America’s most common songbirds. Their remarkable success is likely a testament to the very opportunism that Sherman found so objectionable. From an ecological standpoint, the House Wren’s strategies, however unpalatable to human sensibilities, appear to be highly effective for survival and proliferation.
