The title is the Latin genus name for wrens, so the poem seems to be written from the point of view of a small, busy bird, or at least about one. The wren treats a human home as just another hole to nest in, a "second" shelter after whatever natural cavity it would normally use. The humans, meanwhile, become something odd: the wren's "purveyor / of death and strangers."
That last phrase is the sharp turn. From the bird's side, people may bring danger, perhaps through cats, traffic, or windows, and they also bring unfamiliar faces coming and going. The poem doesn't say which, so the reader fills in the details.
The speaker seems to feel a quiet humility, even a little unease, at seeing themselves through a creature's eyes. The mood is dry, compact, and slightly unsettling. A cozy image of a bird nesting near a house flips into a reminder that we are not always welcome hosts, only a risky presence in someone else's world.