To just add a comment, I have often joined buzzards in a thermal while flying full sized sailplanes and have never noticed any concern on their part. And yes, they are great thermal locators! I can tell you that you will never outclimb them! And if you're flying and begin a circle, the buzzards will join you thinking that you have a thermal! I did this once in a powered sailplane and when the buzzards joined me but couldn't climb, they gave me the worst look I've ever received from another aviator! But I can also say that that thermaling with a wild bird is one of my most fond memories and it's amazing how they you can watch them feel the air with their feathers as they thermal.

Good luck guys and enjoy!