Originally posted by ks2user I hope no-one minds me saying this.... Pentax has many amazing attributes and I love my camera. But you mention AF tracking is a priority for you. That isn't Pentax's strong suit. If you don't already have a lot of Pentax lenses - it might be better to look at a NIkon body.
They may lack some of the high end image quality features of Pentax - but they can be found with weather sealing and the consensus seems to be they have the best AF for wildlife.
That said I've happily taken pictures of stationary birds from my canoe using the K-S2. I wouldn't fancy my chances with them in flight though.
For BIF and other such things, I have found the K3 quite suitable, thank you.
Of course, the AF may not be Pentax strong point but it is also a matter of user's technique.
For further references, you may want to have a peek at some pictures taken with several "grades" of Pentax K's (you're welcome to peek at my Flickr hereby included in my signature) ... as far as I am concerned,
Perhaps it would be a good idea not to make unfounded "observations" with regards to the K3.