With all the diffraction limited talks, any loss in sharpness can only be seen in very large prints or on dedicated tests. It should not show up in small sizes.

The shutter speed here is 1/320. The normal rule of thumb says that the shutter speed should be 1/focal length. Though one can get sharp shots due to IS and better handholding techniques. It is better to sacrifice some depth of field in favour of shutter speed. A higher shutter speed is likely to result in better sharpness.

You were clicking at ISO 100. These days I use ISO 100 only in very specific cases, as the noise in higher ISOs are acceptable. ISO 100 and 200 are barely distinguishable. So you can easily use ISO 200 in your 7D. Increasing the ISO to 200 would have immediately doubled up your shutter speed. That would have also helped in freezing the leavings and giving an overall perception of sharpness.

Is this a cropped image?

At the moment, the bird is at the centre of the image. Central composition often makes the image static. To start with one can explore the rule of thirds as a compositional guideline.

Opening up the shadows a bit will also strengthen the image. Look forward to more images of this beautiful bird with red eye.

You may check this article on achieving sharp images: Indiawilds: Land of the Tiger. Conservation, Wildlife Photography, Communities

For exposure you may check this article:
Indiawilds: Land of the Tiger. Conservation, Wildlife Photography, Communities

Cheers,
Sabyasachi