I may be tempting fate to post this, but we seem to have at long last conquered the dead-seagull-eating problem. I long ago taught a 'leave it' which worked for many things and a 'swap' which worked for everything else - except dead birds. We live very near the sea and in the winter there are dead gulls on the beach most weeks. Thought I'd share what I did to solve the problem. When Molly picked up a dead bird I sounded really pleased and excited and called her to walk to heel (she already had a good off-lead heel and likes to do this when she's carrying 'treasure' like plastic bottles). We walked back to the car and the first time she wouldn't hand over the bird, so I got in and started the engine, which led to her dropping it. I then gave the bird back to her and let her carry it next to me again, before eventually binning it and then going back onto the beach for another walk. This was repeated each time she picked up a bird (without the engine-starting as after the first time she handed it to me on arrival at the car). Then a couple of weeks ago when I called her to me with a dead bird, she handed it straight to me and a couple of days ago I saw her going towards a particularly manky one and said 'leave it' and she did! (Lots of liver-cake rewards!) So it's taken 2 1/2 years but we got there. Just to add that she doesn't kill the birds- they're already dead.
Oh, well done! The dead seagull thing is a huge challenge. Charlie just rolls in the rotting ones...blurghhhhh......
Try, try, try - it's paid off! That's a great achievement. Coco just about managed a "leave it" with the now rather manky polecat-ferret this morning (OK maybe I pulled on the lead a bit, it really doesn't look nice). Not on the way back though...he grabbed it and dragged it along - but he DID "let go" first time.
That's good Joy Sam loves bringing me long dead critters and proudly presenting them , would be rude to refuse