Welcome to the very..."trying" world of wildlife photography
It's challenging, but I actually really enjoy it. There's something to be said for having the luck/skill/knowledge to be able to get that perfect shot of some rather unwilling subjects.
That said ::
First birdy shot -- Doing a stylish shot through the branches is really, really hard to do. To me, blurry foregrounds are almost always a distraction, especially if the body is covered in any way.
Beauty is in the eye of the beholder, of course, but foreground objects seem to work when the follow a bit of the "pattern-interrupted" rule -- Example : A bright white bird in a thicket of brown reeds, most of the reeds being in focus. There's a lot going on in the first birdy shot, so to me it doesn't work as well as a clear bird shot would work. Great, great technical effort though, as those shots are very hard to pull off.
#2 is my favorite -- It's almost as though the near grey branches are creating a symmetric pattern that the bird is interrupting. Cool stuff!
#3 is also good, but unfortunately you're running into a limitation of your lens -- I'm assuming that's at 300mm at cropped at or almost 100%?
I have the Tamron 70-300 Di LD and (unfortunately) have found you have to be very cautious with your cropping at anything above 220mm or so. I don't care how fast the shutter is, the lens simply isn't sharp enough (for me at least) to support cropping anything above 50%. Of all the shots I've ever taken with the Tamron, only one has even been close to respectable at a 100% crop at 300mm
But, it's a very cheap lens that also doubles for macro. Nowadays, on birds, I use it like a 220mm prime and keep it at F/8.0 unless absolutely neccessary...that's about the longest distance you can get while still having sharpness.
Assuming the resolution *doesn't* bother you, I really like #3. Great post, great composition, good bokeh to drown out the background. Assuming you want more sharpness in the shot, you could attempt a ~220mm shot (trying to mind composition of the surrounding forrestry) to go for a less "birdy only" and more "birdy + woods" shot. Some of them work surprisingly well
I definitely know the feeling of wanting all birdy though. I compare my shots to a guy using a $2000 400mm Canon lens and I felt bad at first, but once I work with the limitations of the Tamron it gives good results.
#4 -- Good patience with the turtles! I tried to capture some just last weekend -- Wow you aren't joking about hearing something small and fleeing! Those guys are quick to dive and will scare at the slightest whisper....Kudos on your patience!