A few things may help. Get down low, very low; eye-level with the duck or lower. Probably won't be able to use a view finder, so many shots may have mis-focused, but keep taking them. Use one of the side focus points, and try to get the duck a little off-centre, but looking towards open space in the frame. If you can get it looking at something interesting, or in an interesting surrounding, even better. If the surrounding/background doesn't add anything (colour, interest, framing etc), then minimise anything that will distract.
Another type of shot will be a close-up head shot looking right at you. Try to get with it's mouth opened and looking angry. This will be
very difficult to get in focus.
Next step, find more interesting things to shoot. Or
actually shoot them and have duck for dinner (check legality in your area).