Hi Jamie, if you have worked with bears before then you know the do's & don'ts.
I like the crop, but as Rachel has mentioned the quality has suffered due to a substantial crop, plus agree on less on the RHS. The light grass can also be an issue and can become a distraction, but hopefully you will have new grass & flowers soon. A little NR just on the BG wouldn't hurt either. I think you have done well under the circumstances and look forward to more soon.
If the 400 is your longst lens then you may wish to think about using an extender as it will give you a longer reach
(closer in to your subject without disturbing them too much), but sadly the trade off is lost stops. The reason I say this is you want to be able to have good enough IQ without having to do large crops, ie try to crop/frame within camera, but give yourself a little extra all around for final cropping. Try to get lower to the ground, but always make sure the bears know where you are at all times so they do not get spooked, but you too need to be aware of others lurking. Don't be affraid to raise the ISO, but try to get the highest SS you can without again, loosing quality. Shooting two bears may/will possible require more f/stop ie f/16
(depending on their position etc), so perhaps go for single bears where f/5.6 or 7.1 will be good enough and you keep you speed high. Also if the subject is far enough away from the BG surroundings shooting at f/5.6 will help defuse the BG nicely.
Good luck.
TFS
Steve