Hummingbirds have superb memories of last meals
Mar 7, 2006

OTTAWA (AFP) - The tiny Rufous hummingbird is able to recall where and when it last dined on the sweet nectar of flowers, according to new research, proving bird brains are smarter than first thought.

The study found the bird, with a brain no bigger than a grain of rice and which feeds on hundreds of flowers each day, could pinpoint the location of flowers it had visited and when the bit of nectar in each would be replenished.

Such episodic memory was previously thought to be exclusive to humans.

"This shows that animals have better memories than we thought and that you don't need a large brain for some complex tasks," study co-author Andrew Hurly told AFP.

"This is an animal whose brain is 7,000 times smaller than ours. It's pretty remarkable that they can combine space information and time intervals together and update them constantly throughout the day. It's a very sophisticated thing to do," the biology professor at the University of Lethbridge in western Canada said.

The groundbreaking study by Canadian and British scientists was published Tuesday in the journal Current Biology.

Scientists followed three rust-colored male birds during their summer migration through Canada's Rocky Mountains, recording how often they visited eight artificial flowers filled with a sucrose solution.

Half of the flowers were refilled at 10-minute intervals and the rest at 20-minute intervals after they had been sucked dry.

Researchers found the birds soon returned to the flowers according to the refill schedule.

Hurly speculated its special cognitive skills are necessary for the hummingbird's survival.

The birds, which weigh a mere 3.2 grams, migrate from southern United States and Mexico to breeding grounds in Alaska, traveling some 1,500 kilometers (930 miles) -- the longest known bird migration proportionate to size.

"It would be a waste of time for a hummingbird to return to (spent) flowers. It would be using too much energy. Hummingbirds are so tiny and their hearts beat so fast, it's really important for them to forage efficiently," Hurly said.

Previous experiments with laboratory animals found similar abilities after extensive training, but this is the first such observation in the wild where the subjects may be distracted by predators, courtships or other, he said.

"This is not a bird sitting on a perch in a quiet laboratory and trying to remember the time lapse between a beep and food being delivered."