There are plenty of bass in Thunderbird, just have to find them. A buddy and I went out there in mid march. Probably caught 12 between the 2 of us with an occasional saugeye in the mix. Bass fishing on tbird is complicated. Most of the brush and timber is occupied by crappie or sand bass. If you have a decent depth finder with sonar and a troller motor you can find honey holes in places that most fishermen fly right over on their way to points or brush piles. There is not much rock on most of the lake bottom, but when you find the rock, its almost a guarantee you'll find the bass. I hope this helps a little bit on your next trip. Good luck to you.