Mountaintop Mining Changing Composition of Songbird Populations

MORGANTOWN, W.Va. -- Mountaintop mining is reducing the number of forest-dependent songbirds in areas adjacent to reclaimed mining sites while increasing the number of shrubland-dependent birds, according to a recent study in Landscape Ecology. 

Researchers conducted breeding bird surveys within forests adjacent to mined lands during 2012-2013, and also obtained additional survey data that used comparable methods during 2008-2013.  They identified and counted birds, then identified the level of forest loss at which specific species increased or decreased in abundance. Knowing what level of forest loss results in changes to specific populations may help resource managers in the future as they manage endangered or threatened species, or species of concern. 

“The landscapes that result after mines are reclaimed are primarily grassland, intermixed with small patches of shrubland and forest instead of extensive tracts of mature forests typical of the Appalachian Region, and this significantly changes the bird community,” said Petra Wood, a U.S. Geological Survey research wildlife biologist and coauthor of the study. “The composition of the bird community within the remaining forests changes with declines in some forest birds and increases in some shrubland birds.”

The study evaluated the bird communities in the forest that remains around the reclaimed habitats in West Virginia and Kentucky. Researchers found that even small amounts of forest lost to mineland or grassland within a landscape resulted in lower abundance for the majority of bird species in the forest that remained adjacent to the reclaimed lands.  Declines in abundance were detected for 12 species of forest interior birds and 11 species of interior edge birds including species of conservation concern such as Cerulean Warbler and Worm-eating Warbler.  But the numbers of some species did go up.

“Some shrubland species, for example the brown thrasher and song sparrow, or forest generalist species such as the brown-headed cowbird and the yellow-throated vireo, did have a positive response to the loss of forest and the gain in mineland or grassland, but most bird species did not,” said Doug Becker, professor of biology at Kutztown University in Pennsylvania and senior author of the study.  “If managers want to take actions that may benefit sensitive, forest-dependent species, they need to minimize the amount of forest lost in a landscape.”

Other studies have documented a loss of forest dependent bird species from reclaimed shrublands and grasslands, which is a response to outright forest loss. 

“Reclaimed lands have very slow succession and rarely develop into native shrublands, let alone mature forest,” said Wood. “There is an effort being made to reclaim mines to forestland through the Appalachian Regional Reforestation Initiative, but only a small fraction of mines use this reclamation approach.  So the forest loss would likely be a long-term loss.”

Mountaintop mining is a type of surface mining used to extract coal in the central Appalachian Region by moving surface layers of soil and rock into adjacent valleys, creating “valley fills.” This type of surface mining occurs primarily in southern West Virginia and eastern Kentucky with smaller portions in Tennessee and western Virginia.  It has a major role in changing the configuration and composition of the forested landscapes that are typically found in the Appalachian Region.

The article, Impacts of mountaintop mining on terrestrial ecosystem integrity: identifying landscape thresholds for avian species in the central Appalachians, United States, by Douglas A. Becker, Petra B. Wood, Michael P. Strager, Christine Mazzarella is available online.