Especially when fall is right around the corner.
Every autumn, the chickadee roams a territory covering tens of square miles, gathering seeds and storing them in hundreds of hiding places in trees and on the ground. Over the harsh winter that follows, the tireless songbird, which weighs about 12 grams and fits inside the typical human hand, faithfully re-visits its caches to feed.
The chickadee's unerring spatial memory is remarkable enough, says Colin Saldanha, assistant professor of biological sciences at Lehigh University and an anatomist who has studied songbirds for six years.
But it is what happens inside the tiny songbird's brain that Saldanha finds amazing. In the fall, as the chickadee is gathering and storing seeds, Saldanha says, its hippocampus, the part of the brain responsible for spatial organization and memory in many vertebrates, expands in volume by approximately 30 percent by adding new nerve cells. In songbirds, the hippocampus is located on the dorsal surface of the forebrain right beneath the skull. In mammals, the hippocampus is located beneath the cortex.
In the spring, when its feats of memory are needed less, the chickadee's hippocampus shrinks back to its normal size, Saldanha says.
"To see this happen under natural conditions," says Saldanha, who began studying the black-capped chickadee in 2001, "is truly awe-inspiring.
"Our hypothesis is that this exaggerated growth occurs when the birds need it the most - and we're interested in finding out what exactly triggers it."
Songbirds are the first species of vertebrate in which brain growth during adulthood has been found to occur, Saldanha says. By studying neurogenesis in the black-capped chickadee, Saldanha hopes to le
Contact: Kurt Pfitzer