Birds of the Shrublands

Shrublands once moved across the land in response to fire, and shrubland birds thrived. Bringing back this habitat of impermanence may be the next big thing in conservation.

My favorite day in the field is a day in June when the birds invite me into their living room. I pull up a “chair” at the edge of a shrubby meadow and enjoy myself in plenty of good company — indigo buntings carrying worms into the nursery, catbirds mewing from the fridge, rumpled song sparrows peering from a footstool, and a cuckoo toc-toc-tocking from just outside the window.

The birds make these places so convincingly their own each summer that it’s hard to believe their homes are not at least as permanent as mine. Yet the shrubland I am observing on this perfect day may be utterly changed in just a few years, with most of its birds gone. Unlike so many disappearing habitats, though, this is all part of a natural cycle.

That cycle hinges on disturbance. If a fire roars through, or a brush clearing crew, and if the site is large enough, grassland birds may replace the shrubland birds, which will search for more suitable homes elsewhere. If left undisturbed, the landscape of shrubs will transition to thickets and forests, attracting yet a different set of birds.

For thousands of years, the grand fires that annually redeemed the grasslands also imparted a rhythm to shrublands. “Barrens” of stunted oaks, and thickets of hazel, plum, crab, hawthorn, dogwood, viburnum, blackberry, rose, and others bounded and shuffled around the landscape in response to fire. Other disturbances — beaver dams, major floods, and windstorms — also played a part.

Once the large fires were stopped, we lost our native shrublands along with our grasslands. Large oak barrens and thickets of hazel are a thing of the past.

Despite these enormous changes, most shrubland bird species are still present in the region — a testament to their adaptability. Today, they are just as likely to be using invasives such as honeysuckle, buckthorn, or Osage orange as they are native plum or viburnum. While some animals such as butterflies will only use one specific plant species, birds are less picky, responding to the structure of shrubs and shrublands — if a plant’s got the right shape, size, height, and location, it will probably serve for shelter, lookout, nest site, and camouflage from predators.

But numbers of many shrubland species are declining, and some of these declines are beginning to cause real concern. In fact, only grassland birds as a group are declining more rapidly than shrubland birds across the United States.