Clever birds don't have it all

Some birds solved the problem in seconds. Others took longer, some of them pecking at the stick and noting the movement of the larva before solving the puzzle. Despite these successes overall, only 40 per cent of the birds tested were able to solve the problem.

The birds were isolated from one another while encountering the test so they could not depend on “social learning”, ie acquiring the learned skills of another, Quinn says. The tested birds were then tagged with small radio transmitters and released back into the wild after their short captivity.

At this point, the experiment switched out of the lab and into the woods. The research team were able to keep tabs on the birds via their tagging system and could track how the “smart” birds performed in the wild versus the birds who were unable to solve the food puzzle.

On initial inspection, the clever birds seemed to be coping better with their environment, Quinn says. The team found the problem solvers were producing more eggs than those who had failed the test. They were also able to make use of a smaller part of the wood when foraging for food compared to the others.

They laid more eggs and these delivered more hatchlings, with clutch size an indicator of breeding fitness. “Either they were better at finding food and could lay more eggs or they could provide for the hatchlings better. That suggests they were able to exploit the environment more effectively.”

Unexpectedly, the smart birds were also more likely to abandon their fledglings, to fly away apparently without provocation and leave their nests behind with a subsequent loss of the young.

The research team put this down to a greater sensitivity on the part of these birds to the presence of humans “who they viewed as potential predators at the nest”, he suggests.

By comparison, the “bird brains” needed about twice as much foraging space in the woods to support themselves, but they were less likely to take off and leave their young behind.

This difference between the two sets of birds tended to level out breeding success. The greater number of surviving chicks produced by the non-solver birds managed to keep up with the increased number of fledglings produced by the smart birds because of their higher mortality rate. “In the end, good and poor solvers did equally well living in the wild,” Quinn says.

In this example, evolution has not favoured the birds that were able to solve the problem so there was no apparent advantage to being smart. The only advantage – as perceived by a human – was that smarter foraging meant a shorter working day in the search for food, he says.

“For me, what was amazing is that this simple problem-solving test we did in captivity predicted how well birds bred when they were released back into the wild.”