Anyone familiar with Hawk Mountain in Kempton, PA

Hi. I hope this is the right spot for this question. I saw where the bald eagles will be at Hawk Mountain in late August, followed by Cooper Hawks. Has anyone been there, and will my 400mm be adequate? I have heard that some people have used 500mm and 600mm lenses at Conowingo Dam. I do not want to do major cropping. I can rent a 1.4 or 2.0 extender if need be. BTW, I am using a 5DM3, and the 400mm is f/5.6. I know, get/rent a 1Dx and 400 f/4. thank you for your input.

I wanted to post this in the Birds forum, but, put it here by mistake. How do I move it, or, does a Moderator do it? Sorry. Thank you.