Get a duck with good eyes. Near sighted ducks sometimes fail to recognise that they are on the old gauges and will go flogging into the nearest hill. Very near sighted ducks will not realise that they have been thrown out and will descend to the ground in a sitting position. This is a most difficult manoeuvre to follow in an airplane. Choose your duck carefully, it is easy to confuse ducks with geese.
Many large birds look alike.
While they are very competent instrument flyers, geese seldom want to go in the same direction that you do. If your duck seems to be taking a heading to Ireland or Sweden, you may be safe in assuming that someone has given you a goose.