Birds help get the bugs out of sapped pine
By Katy Human Denver Post Staff Writer
Article Last Updated: 08/01/2007 06:03:26 AM MDT
Birds, like this chickadee, go out on a limb to help pine trees grow
faster. (Special to The Post / Bill Schmoker)
Hanging upside-down to gobble insects from pine boughs, chickadees and
other birds do pine forests a great service - helping trees grow faster,
by as much as a third, according to a new study.
Fewer aphids and other sap-sucking bugs plague the trees when birds are
around, said Kailen Mooney, a doctoral graduate from the University of
Colorado at Boulder.
When birds are excluded from branches, those bugs thrive, he found.
"It's that old saying, 'The enemy of your enemy is your friend,"' said
Mooney, who will become an assistant pro fessor at the University of
California at Irvine this fall.
"Birds are beneficial to pines," he said. "To see the forest, you need to
look beyond the trees."
A CU doctoral graduate says birds such as chickadees, like the one shown
here, and nuthatches are "beneficial to pines." (Special to The Post /
For three years, Mooney maintained net bags on the limbs of some ponderosa
pines in an experimental forest west of Colorado Springs.
Chickadees, nuthatches and warblers couldn't get a grip on the branches
and tended to stay away from those trees, he said.
After three years, trees with birds grew about a third more wood than
nearby birdless trees and 18 percent more "foliage," or needle mass,
Mooney reported in the latest issue of the journal Ecology.
The study is the first to report indirect effects of birds on trees in
Western pine forests, Mooney said.
The trees weren't infected with pine beetles, he said.
The findings - that birds such as chickadees and nuthatches help trees
grow - should be considered by anyone worried about the health of
Colorado's forests, Mooney said.
"In deciding how to manage beetle-kill areas after they've been attacked,
well, to try to maintain a high abundance of these birds is just common
sense," Mooney said.
In other types of ecosystems, birds play critical roles - also indirectly
- said Robert Marquis, an ecologist at the University of Missouri.
They peck sea urchins from intertidal rocks, affecting the growth of
algae, and glean grasshoppers from tall grasses, affecting prairies.
"It can be hard to imagine birds can actually affect the growth of trees,"
Marquis said. "Birds are so small and trees are really big. But it turns
out birds are very important."
Staff writer Katy Human can be reached at 303-954-1910 or
The material in this post is distributed without
profit to those who have expressed a prior interest
in receiving the included information for research
and educational purposes.For more information go to:
If you wish to use copyrighted material from this
email for purposes that go beyond 'fair use', you
must obtain permission from the copyright owner.