still some work left to do, but almost there! (I hope)
The modeling and composition are both great,
I would advise bump and spec map on the plane… Also, the texture looks fuzzy? Otherwise the texturing is good, however the area with the bird seems to lack some light, at least for an outdoor scene. Another thing that could make the wood more realistic is bevel, the edges are quite sharp. Try using more depth of field to focus on the bird, and perhaps a rim light.
Beside what Dark Matter said i would give the bird a more “relaxed” pose and decrease the sun lamp size (if you’re using that), to obtain sharper shadows.
the poor birds head looks squashed… is that on purpose? ow.
i think i like the sharp edges on the wood though, i have seen plenty of wood like that. ;D
The leftmost insulator is blocked by the pole. There wouldn’t be one there. They also didn’t install these on the underside of the crossbeam, since the weight of the wire would tend to pull the insulator off its mounting peg.
the colors are a bit flat, little contrast, to much light ?
i agree with razorblade… just use GIMP, its free and awesome. 
Wow, I like your scene a lot! It’s almost real looking… But that little birdie looks…overfed, and his head looks like it was bashed at from the side…
yeah, it doesnt look like the bird is a very good flyer…