Window strike Warbler?

Without a photo it's impossible for say. Also as we are a mainly British forum so knowledge of American birds is a bit limited.

To prevent strikes there are a number of things but nothing is a 100% - if the bird hit the window trying to escape a predator not much will make a difference. Use blinds or curtains to reduce/disrupt reflection, stickers on glass can help. Shutters on the outside that can be closed when the sun causes the most reflection. I've also heard of Saran Wrap being used against the glass to dull it down but not sure about that