SNAGS: PART II

Some years ago, an arborist made a snag from one of our yard trees. Less than a decade has passed, but it is beginning to soften up, attracting he interest of some cavity-nesting birds. The nuthatch in this video spent several long days working on a couple of nest cavities, only to be run off by a northern flicker. After it made some test holes, the flicker decided it wasn’t the perfect place. Meanwhile, it is a favorite perch for the dawn chorus.

Equally interesting in the saga of this big snag, is the cascade of changes initiated by the sudden absence of a large tree. Resources – light is one of the most important – are limited in ecosystems. A large tree taking up air space and light has a big effect on surrounding vegetation. When it is gone, suddenly other trees and plants shift into high gear to take maximum advantage of the newly abundant resource. Birds and other wildlife are quick to make use of the changed environment too.

The tree-that-became-a-snag in our yard was suppressing nearby trees, and since it died, its neighbors have sprouted new growth from dormant buds on their trunks and branches (called epicormic branching). The thick new growth is fine for nest platforms and cover; Steller’s jays (Cyanocitta stelleri) are taking advantage. We watched a pair put together a nest in this limb thick with new growth (see video here). When trees snap off and lose branches naturally, the same thing occurs. This is why disturbances like wind and freeze damage create great habitat.

Thickened new growth makes better nest platforms

The tree pictured below was so close to its neighbor, that shaded lower branches died off. But new ones were able to re-sprout when exposed to sun. The tree has thick branching from dormant buds on the limbs, and epicormic buds on the trunk that exist for just this moment of newly available light.

Light gaps are important for regeneration in dense forests, and for diversity of species. This is where seedling trees, shrubs, annuals, and perennials get a start. Their blooms provide nectar for pollinators and food for animals.