Mallard Couple Preening

First day with Sigma 120-400mm: several test shots including these two Mallards. This particular shot wasn't the sharpest of shots, but it was more candid than some of the others. Also, it allowed me to see how much sharpness and I could recover in post-processing.

Canon EOS 60D
Lens: Sigma DG 120-400mm 1:4.5-5.6 APO OS HSM
Focal Length: 415mm (w/ TC)
f/10 (accident)
Shutter 1/1000
ISO 200
Kenko 1.4X Teleplus Pro 300 DGX
Monopod
Cropped to get up close, but I don't know exactly how much

Comments and constructive criticism is greatly appreciated.