Abstract concepts are a tough nut to quack, but ducklings apparently manage it
Ducklings are born with an ability to understand abstract concepts not usually associated with fledgling bird brains, research has shown.
Their instinctive recognition of "same" and "different" helps them, just 15 minutes after hatching, to identify their mother and stick behind her.
Scientists at Oxford University conducted tests to observe how the same "imprinting" process bonded young ducklings to pairs of inanimate objects.
Newly-hatched ducklings were first presented with a pair of objects which were either the same or different in shape or colour.
The study showed that the ducklings were able to recognise the "same" or "different" relationship between object pairs. This in turn helped them to choose which objects to follow when they were moved.
For example, having first "imprinted" itself on a pair of spherical objects, a duckling might then be given the choice of following either a pair of identical pyramids or a non-matching square-sided cube and rectangular cuboid.
It would choose the two pyramids - understanding that like the spheres, they were the same as each other, the scientists found.
Professor Alex Kacelnik, from Oxford University's Department of Zoology, said: "To our knowledge this is the first demonstration of a non-human organism learning to discriminate between abstract relational concepts without any reinforcement training.
"The other animals that have demonstrated this ability have all done so by being repeatedly rewarded for correct performance, while our ducklings did it spontaneously, thanks to their predisposition to imprint when very young.
"And because imprinting happens so quickly, the ducklings learned to discriminate relational concepts much faster than other species, and with a similar level of precision."
The research is reported in the latest issue of the journal Science.
First author Antone Martinho, a doctoral student in Prof Kacelnik's department, said the discovery might seem surprising but made biological sense.
He added: "When a duckling is young, it needs to be able to stay near its mother for protection, and an error in identifying her could be fatal.
"Ducks walk, swim and fly, and are constantly changing their exact shape and appearance as they extend their wings or become partially submerged, or even change angle with respect to the viewer.
"If the ducklings just had a visual 'snapshot' of their mother, they would lose her. They need to be able to flexibly and reliably identify her, and a library of concepts and characteristics describing her is a much more efficient way to do so, compared with a visual memory of every possible configuration of the mother and her environment.
"Still, this is an unexpected feat for a duckling, and a further reminder that 'bird-brain' is quite an unfair slur."