"The Writer" poetic analysis

The first half is straightforward. His daughter is writing. He's a writer himself, so he knows what's involved with it--how you pour your heart into it. He hears her stop and start and stop and start. With each stop, he, the whole house (he suggests in that image) thinks she may have hit the wall or, in other words, run out of ideas or what she needed to say and ended up frustrated and sad, as we all are (as you are right this minute because you can't understand the poem) with writer's block. 
Now think of the starling (type of bird). He's telling us about something that happened before, literally. A starling got stuck in the bedroom and couldn't get out. They went in and opened the window (the sash) in hopes that the bird would find his way out. Like birds do, he kept banging against things in a panic trying to escape, and each effort left him banged up, bloody, maybe even dead. Then, finally, because he tried again, he found the window. 
Now put the two stories together. The poet's memory of that bird relates to how he's feeling about his daughter and hearing her typing, stopping, trying again. She's trying to express herself with her writing. She's "hitting the wall" as I said before, like the bird. Every now and then, something is stopping her, and the poet doesn't know if she'll be able to start again--if, like the bird, she'll survive this pause and lapse of thought without the frustration and pain of writer's block--and try again to soar through her writing. (Like the bird who finally takes off and makes it out the window and back into the sky.) 
He wants happiness and all things good for his daughter. He could walk in and tell her writing is not worth the heartache or the bother, but because she is typing so fast, he knows she's passionate about what she's trying to do. Instead of saving her the pain of being frustrated, he admires her for the fact that, like the bird, she keeps trying. He knows she's on her way to finding her own version of soaring through the sky through all these hard efforts, and he wishes that for her.