Monday, February 13, 2012

Birds Identify Trees

Bluebird- Mike Onyon
It appears that birds can select their trees to feast on just like we pick a nice restaurant.  According to an article at, birds are able to pick the right tree species to increase their chance of finding a great meal.  The study reported in the American Naturalist showed that chickadees and other birds select the type of trees that they dine in as well as their targeted caterpillar variety.

Many caterpillar species have a limited number of tree species to choose from as their obligate food source.  In addition, their mother's choice of the tree where she lays the egg affects their success.  The healthiest tree would feed the greatest number of juicy caterpillars.  Apparently birds figure this out and select their tree species, so the individual caterpillar's survival odds on a great dinner tree are much smaller.

That being said, there are two competing strategies.  Eating on a less desirable tree may produce smaller and less healthy caterpillars with a lesser chance of successful survival.  Dining on the healthy tree may increase the gastronomic odds but at the risk of increased predation.  Caterpillars living on an nice juicy black cherry had a 90% chance of being eaten by a bird.

Although the nutritious cherry tree leaves produce "fat cats" (think 5 star Michelin guide) we don't know which strategy produces the most adults in the long run.  But at least they don't have to go far for a good meal.  As the saying goes, "Fat cats don't hunt."

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