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PARC Research

Louisiana Waterthrush Project at Powdermill Avian Research Center (PARC)

Louisiana WaterthrushAcid Mine Drainage and our Mountain Streams

Carnegie Museum of Natural History’s biological research station Powdermill Nature Reserve is uniquely positioned to study the effect of acid mine drainage pollution on songbird populations that live along stream banks (obligate riparian species).

At PARC, differences in stream quality exist between unpolluted Powdermill Run and the adjacent, acidified Laurel Run. To take advantage of the opportunity provided, a program was established to study the effects of acid mine drainage pollution (AMD) of headwater streams on the demographics, behavioral ecology, productivity, and survivorship of selected songbirds. For this project the Louisiana Waterthrush (Seiurus motacilla; LOWA) was chosen.

Aquatic macroinvertebrates provide the main diet of the Louisiana Waterthrush; however, many of these small, spineless organisms cannot survive or reproduce in acid-polluted streams.

Powdermill Run offers a pH-neutral environment, has abundant macroinvertebrates, and supports a variety of fish species.

Laurel Run, a stream which has been impacted by drainage from two abandoned coal mines, is acidic (with a pH between 4.0 and 5.0), and stream samples show high levels of dissolved aluminum and iron.  Laurel Run therefore has reduced macroinvertebrate diversity and density, and supports no fish.

The Louisiana Waterthrush Study

Louisiana WaterthrushStarting in 1996, Field Ornithology Projects Coordinator Robert S. Mulvihill, began the LOWA study to determine whether or not the pollution of Laurel Run affects the breeding density, reproductive success, foraging behavior, and survivorship of the Louisiana Waterthrush. 

Initial results demonstrated that the number of territories, pairing success, and nesting densities of LOWAs nesting along the acidified stream were lower (four territories and 50% pairing success at Laurel Run compared to 11 territories and 91% pairing success along Powdermill Run.)

Within two years of beginning the study, two sources of acid mine drainage on Laurel Run were remediated, in part by using passive treatment technologies.  Since then, PARC has continued to monitor changes in the Laurel Run LOWA and macroinvertebrate populations.

Remediation efforts continue, and researchers expect to see LOWA numbers along Laurel Run increase to levels comparable to those associated with the unimpacted Powdermill Run.  These improvements signal that the ecological balance of this picturesque stream has been substantially restored, even after half a century of degradation due to acid mine drainage.

Contributing funding sources for this study have come from:

  • Pennsylvania's Wild Resource Conservation Fund (WRCF)
  • Loyalhanna Watershed Association Research Fund of Carnegie Museum of Natural History


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