Birds didn't show up in Rutherford's poetry quite as much as they did in his plays. They were often ever-present, written as elements of the background, sometimes sentinels and sometimes silent judges. They're usually interpreted as symbols of nature as constant: While the characters do terrible things and great things and while empires fall and people betray one another and have to face their deepest fears, nature is always there, surprisingly unaffected.
In one of his later plays, And For Pleasure, Striga while content with the state of her life has this odd conversation with Ozzy. It's one of my favourite moments from his plays though no critic has ever commented on it. But Striga's comments on birds were one of the reasons I decided to make this blog, so I'll excerpt:
People don't respect me. They don't care about me. I'd be surprised if they remember my birthday tomorrow. But it's just a birthday. They remember my death-day, they all do; it's when all the bluejays flock to my bedroom window. May 4th. I don't yet know the year. But that's the day I'll die. I can tell from the way they look in through the glazing, their eyes knowing and their beaks opening for calls but no sound coming out. My death will be no secret.