Robins can judge meal size better than other animals

London - Robins appear to have an ability to count numbers and choose the lager meal, according to a new study.

Alexis Garland at Victoria University of Wellington in New Zealand let 36 wild North Island robins choose one of two wells after seeing different numbers of mealworms dropped en masse into each.

Most picked the fuller well as long as the ratio was below 0.75 - correctly selecting, say, 64 over 32 worms. The mechanism at work here is called ratio-based representation and involves guessing which large group of items has the bigger bulk.

The robins did even better when the worms were dropped into the wells one by one and covered so that the masses could not be compared: they managed a ratio of 0.88, though with a smaller number of worms.

For the largest trial at this ratio - 14 versus 16 worms - most robins chose correctly.

However, other animals tested like this have only managed to track about four items.

“Discriminating between two large groups of objects that are close in number would be pretty exceptional for any animal or human, but that’s exactly what the robins did,” New Scientist quoted Garland as saying.

According to Garland, Robins hide multiple food items in several places so it may be advantageous to distinguish more from less quickly.