I use Nikon gear for my SLR bird photography, but I think the Pentax K-3 looks like a great camera and I applaud Pentax/Ricoh for putting forward a very serious APS-C body, with "pro" features like full metal alloy construction, more capable autofocus, fast shooting with 8.3 fps and ~23 frame raw buffer. Indeed the K-3 resembles the Nikon D300/s upgrade that a bunch of us frustrated Nikon people have wanted forever. Thom Hogan even titled his reaction, "
Meanwhile Meet the Pentax D400."
So I wish Pentax all the success in the world with the K-3. As far as I'm concerned APS-C is the ideal format for wildlife--especially birds, and Pentax has an advantage in that their telephoto lenses are designed for the smaller APS-C sensor and thus the lenses can be a little smaller/lighter (560mm = 6.7 lbs). Pentax will probably always have that advantage because I don't think Nikon or Canon will ever make a line of "pro" super-telephoto lenses designed for APS-C. And if Nikon keeps dragging its heels supporting serious APS-C bodies & lenses, who knows, maybe someday I'll switch to Pentax.
Dave