The eagles are definitely back

We did the Austin-to-Llano trip three times during the past two weeks (family events & feasts, woot!). Each time, at least one eagle was visible from Hwy29. And.. this was not during the peak morning/evening hours.
Of course, we only brought the p/s instead of the slr gear. sigh...
From prior experience - bring as much lens as possible. A few years ago, I gave it a try with my 10D w/300 + 2x. Even with the lens and teleconverter on a 1.6x factor body felt short at times.
Some random suggestions - Tripod: Required. Work with medium to light tension so that you can follow the eagles in flight. If they're on the nest, tighten it up and use mirror lockup/remote, if available. Remember, the super telephoto ranges magnify any camera movement.
Oh, and if worse comes to worse, you can use one of the fence posts as a temporary tripod.
ISO: Work with the slowest ISO possible for the lighting/action. Given the distance to the nest versus the maximum lens you have available means that it's likely that you'll have some significant post-production cropping.
Exposure: You have to be careful about the exposure. Unless you're really tight on the nest/bird, the meter is mainly going to be reading the sky (and the eagles will end up silhouettes). It's a great time to practice manual metering.
Timing: In the early morning and evening hours, the eagles are more active out of the nest. If they are staying in the nest, it's even tough to spot the top of their head. If you have some time to kill, drop by Llano, have some BBQ, take some shots of downtown, wander along the river, look for landscapes, details, etc. Don't have a set plan except for an open schedule. Have some fun.
Good Luck!