What began as a cool wildlife spectacle of egrets and herons nesting in the campus' Shields Oak Grove has become pretty unpleasant. 

"Uh yeah…I mean you don't want to be near there when all the birds are there." 

Ellen Zagory is director of horticulture for the UC Davis Arboretum. She says the bird droppings are not only gross. They contain ammonia which is toxic to the trees and causes the leaves to drop off. 

"And then leaves that don't fall off right away get completely covered in white and then they can't photosynthesis and it inhibits the trees' ability to grow." 

So the campus is installing laser lights and will sound off harmless distress calls to keep the birds away this spring. 

"And it's to startle the birds so that they are not as comfortable there and they'll find a more suitable place for them to nest." 

Zagory says the number of nests has skyrocketed in the past few years. In 2006 there were about 630 nests. Now there are more than 860.