Alan great kingfisher!
Mind saying what lens you used and whether you cropped at all.
My experience with the 7d is that any images above 320 iso or so just do not allow any cropping, unlike 5diii raws, which allow cropping to about 100 % without any need for noise reduction. For me it is usually better to use the 5diii and crop vs getting the extra reach from the 7d. I think there may be variability in the sensors in the 7 d
300mm f/2.8 II with 2xTC III at f/8. It is the centre 44% of the total. I routinely use Iso 400 and crop to a 1000x1000 pixels. The main problem for me is the lack of consistency of focus of the 7D - and it is not just mine, the tests by FoCal, Lens Rentals etc show the same. I have just bought a 5D III. Not only is the Iso performance much better, the consistency of focus is superb and it focusses much faster with the 300mm f/2.8 + 2xTC, which was slow on the 7D. I am keeping my 7D as a back up, and for my wife and grandson to use as it is still good enough.
5D IV, 5DS R, 7D II, EOS-M, Powershot G3 X, 400mm DO II, 300/2.8 II, 1.4xTC III, 2xTC III, EF 1.8 STM, EF 70-200/4 IS, EF 24-105, 15-85, 100-400 II, Sigma 10-20, Sigma 150-600mm C, EOS-M 18-55, f/2 22, 11-22