mostly philippine brown shrike birds photo

I like to shoot birds too.
While i shoot i try to check for a good background. Here in the first 4 photo i tried.
btw, my shooting style is i walk around the park and try to see and listen to birds.
That means i seldom stay in one area. I do this so i can shoot more kinds of birds.

Camera Info
Device: Nikon D7100
Lens: VR 150-600mm f/5-6.3G
Focal Length: 600mm
Focus Mode: AF-A
AF-Area Mode: Single
VR: ON
AF Fine Tune: OFF
Exposure
Aperture: f/7.1
Shutter Speed: 1/800s
Exposure Mode: Manual
Exposure Comp.: 0EV
Exposure Tuning:
Metering: Spot
ISO Sensitivity: Auto (ISO 250)