The duck test is a form of abductive reasoning. If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck. More specifically, these ones run, so they must be runner ducks!
Watercolour illustration of Ducks by Daniel Mackie. Printed on high quality 330gsm card. Cards are 7 x 5 inches.
Cards are blank inside so can be used for any purpose