Evolved owls with sound-dampening feathers in Metropoli Perdida. Hunt ruins silently. Only indication: sudden absence of other sound when they pass.
Evolved owls. Sound-dampening feathers allowing completely silent flight through enclosed ruin spaces. Hunt the ruins without any audible signature.
Only indication of presence: sudden absence of surrounding ambient sound when passing through — everything else stops. Urban rats in Metropoli Perdida have evolved acute vibration sensitivity in direct response. Where the rats freeze, the Strix is passing overhead.