The Secret Lives of Wrens

The Eurasian wren may be one of Britain's smallest birds, but has a mighty personality and lives within a cut-throat society.

I've long considered the wren one of my favourite birds. Mouse-like, bouncing through the undergrowth, and a shy, yet fiercely territorial, species. Akin to an excitable atom, buzzing from one perch to another, Troglodytes troglodytes has stared me down my camera lens many a time as I wrestled with the focus. More often than not, these bouncing birds, with their strikingly loud song and dashing eye stripe, moved quickly enough that I missed the shot. As any wildlife photographer will know, that's partly what makes it so thrilling. But, in my hours spent perched along a woodland path in wait, I began to notice just how rich and busy the lives of wrens truly are.

Male and female Eurasian wrens (Troglodytes troglodytes) are virtually undistinguishable at a quick glance, but their behaviour in the breeding season can help. Males build a selection of domed nests, using twigs and moss, which females will select from before lining the nests with feathers. Image Credits: @madelaineinthewild

To quote Shakespeare's A Midsummer Night's Dream: "And though she be but little, she is fierce." During the breeding season, between March and May, female wrens relentlessly defend their nesting territories against competing females and intruders. The males are just as, if not more, ferocious when it comes to staking their claim on high-quality breeding territories.

Wrens exhibit polygyny, a strategy where males mate with multiple females in their territory. With 8% of bird species globally demonstrating polygyny, it's the second most common breeding strategy. Prior to breeding, males painstakingly construct an array of nests, shaped like little domes, for females entering their territory to choose from. Once a female selects a nest, the birds breed after she lines it with feathers, and the polygynous male often repeats this process with more than one female.

To attract and host multiple females, a male wren must occupy a high-quality territory with sufficient nest sites and food resources to go around. Locating and defending these becomes crucial, with the success of a male's breeding season weighted on his ability to ward off unwanted rivals. In fact, it's so important that males may pre-emptively begin ahead of the breeding season, identifying territories and guarding against infiltration during the winter months, according to new research published in the journal Ardea (2026).

In the secret lives of wrens, there are a number of ways to be territorial, and all can be energetically costly. Using songs as aggressive signals, for example, or making a sharp tic tic sound to alert others to your presence. Some territorial behaviour even includes physically chasing away intruders and competitors. In a study published in The Wilson Journal of Ornithology (2025), a nest-building male was even seen performing a distraction display, leading a Japanese striped snake (Elaphe quadrivirgata) away from its nest.

Circling once more to those famous Shakespearian words, though these wrens be but little, they are incredibly fierce. From demonstrating impeccable work ethic in nest construction, to taking on adversaries much bigger than themselves, perhaps wrens are living proof that when it comes to nature, size isn't everything.

About the Author:

Madelaine is a Zoology and Science Communication graduate, now working as a Guide at a BIAZA-accredited aquarium. Passionate about engagement with science and nature, and rediscovering a love of writing, she aims to document her experiences with the wild through blogs, wildlife photography, and tales of the natural world.