Songbirds, Berries, and Anti-oxidants

Researchers believe that migratory songbirds at Block Island choose to eat arrow-wood berries specifically for their anti-oxidant content. The berries might relieve some of the physical stress that songbirds endure during long-distance migration flights. Arrow-wood berries contain higher levels of anti-oxidants than many of the other berries present on the island at the same time.

"When I started studying birds during their migratory stopover on Block Island, I was impressed that most of the migratory birds ate berry fruits even though they usually eat insects or seeds at other times of the year," said McWilliams, who came to URI in 1999. "I began studying the relationship between the nutritional qualities of fruits and how those nutrients might fuel migration." ...

The research indicates that birds prefer to eat certain fruits that have more antioxidants and key nutrients. In return, the seeds in the berries are dispersed by the birds. "It's the way plants ensure their survival. Birds eat the berries, digest them and defecate the seeds over wide areas," McWilliams said.

"Meanwhile, the birds are attracted to the berries because of their rich color, which we believe is a plant's response to the stress of constant exposure to the sun and other stresses. Berry color could be a plant's way of fighting oxidative stress. It's a partnership that benefits plant and bird."

The Seeram-McWilliams partnership will continue. "We've only measured a few of these anti-oxidants," Seeram said. "Our next step is to determine how birds can detect these compounds."

"Whenever we exercise, we undergo oxidative stress, and the same is true for birds," McWilliams said. "We're flying birds in wind tunnels to produce oxidative stress, and then we are going to see if anti-oxidants found in these berries alleviate that stress," McWilliams said.

The research may benefit human health as well as bird conservation. If further research shows the direct link between bird health and diet, then the findings will play a critical role in habitat protection for migratory birds, McWilliams said.

This is interesting, if true. I wonder how much of the preference could be explained simply by availability, size, or taste. I also wonder whether this would really mean much for humans. Anti-oxidants already receive quite a lot of publicity for their ability to treat or prevent various ailments. I am not sure that adding one more would change food consumption habits.