Pine trees have the mountain chickadee, redbrested nuthatch, the pygmy nuthatch and the yellow rumped warbler to thank for large, healthy branches. A new University of Colorado study shows that when these birds are present pines may grow a third larger. The birds keep away insects which feed off the tree. By eating ants, spiders and other arthropods, they also likely change the trees' flavor. Trees with birds create more of a chemical called terpene, which may keep away insects like the bark beetle and mammals like the squirrel. So, the birds benefit from shelter, the pines from insect protection and the rest of us from a little songbird music.