The area was chosen because of its location close to many poultry farms.
The birds would have been shot for sport, so the British Association for Shooting and Conservation was asked to collect samples for analysis.
The move is part of efforts designed to pick up the first signs of the disease in the UK. The results gathered in the country so far have been negative.
It is currently open season on ducks like the mallard, wigeon and teal.
Relatively few migrate to Scotland from eastern Europe, where the H5N1 virus has been found in Romania, Russia and Turkey.
Negative results
About 200 ducks will be tested on the Firth of Forth in case the disease has slipped in.
Andy Macfarlane, the chairman of the British Association for Shooting and Conservation in Scotland, said the birds being killed would have been shot anyway.
"It is a front line of defence, just to have a look, and if we get negative results that's fine. We are not looking for positives," he said.
Chief vet Charles Milne said the 10 samples processed so far in Scotland had all been negative.