NATURE - Clever birds don't have it all - IRELAND

 

Birds with brains: great tits were set tasks to investigate if their perceived higher intelligence helps them survive in the wild. Photograph: John Quinn

 

DICK AHLSTROM

Studies show some great tits are remarkably clever when it comes to solving problems to get at food. But does this help them in the wild?

BE CAREFUL who you call a bird brain, you may be paying them a compliment. Some bird species exhibit remarkable intelligence, among them the great tit, which is a common garden bird.

The New Caledonian crow is top of the leader board with its capacity to fashion tools to retrieve food, but the local great tit doesn’t do too badly when it comes to solving problems. Dr John Quinn, a specialist in animal personality and cognition, began to study the bird four years ago while at Oxford University. He and his team caught wild great tits in a nearby wood and set the birds a simple problem. If they solved it, they would get at some food.

Now a lecturer in ecology at University College Cork, Quinn had a particular purpose in mind when conducting the experiments. “We are trying to understand why we get individual variations in the birds’ cognitive ability,” he says.

They were also trying to discover whether it is “better to be brighter” – whether the birds that were able to solve the puzzle also did better generally, either reproductively or in terms of survival. “The purpose of our study was simple: to test if it was better being a problem-solver. That hadn’t been tested in the past. Do they do better or do all individuals do equally well in the end?

“It has been known for many years that relatively clever species tend to be adapted to living in more challenging environments than their less intelligent counterparts,” he said.

Another aspect of general genetic “fitness” is the number of eggs that appear in a nest. More eggs can mean more fledglings.

Quinn conducted the research while at Oxford, but moved to UCC’s school of biological, earth and environmental sciences in January. He submitted the research and it was published recently in the journal Current Biology.

The research team – including Ella Cole, who remained at Oxford, and Julie Morand-Ferron, now at the University of Ottawa – collected great tits in Wytham Wood near the college, ultimately testing 700.

The great tit is a highly successful bird. “We know they are very innovative in the wild,” he says. These are the birds that pioneered the practice of raiding home milk deliveries, pecking open foil milk-bottle caps to steal cream. “They are quite an adaptive species.”

The birds were held for one day. Each one was placed in a cage to see if it could solve a puzzle. The incentive was to acquire a juicy wax moth larva, which had been placed in a clear plastic tube and was readily visible to the bird. The prize was supported by a small platform held in place by a stick of wood. Removal of the stick caused the platform to fall to the base of the tube where the bird could get at it – and with it the larva.

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.”