Louisiana Waterthrush Project at Powdermill Avian Research
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
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
The Louisiana Waterthrush Study
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
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
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