The extraction of natural gas from shale formations in Appalachia has become a contentious political and environmental issue partially due to concerns over habitat loss and the fragmentation and degradation of wildlife habitat. However to date, no study has examined the effects of Marcellus shale gas development on avian populations. Researchers at the U.S. Geological Survey (USGS) Pennsylvania Cooperative Fish and Wildlife Research Unit at Penn State University are developing new models to evaluate the impacts of this development on bird populations in the region.

The abundance and occupancy probability of many grassland and interior forest bird species consistently increases with habitat area. Increased exposure to habitat edges can negatively affect grassland and interior forest bird populations by reducing mating and breeding success and increasing predation and parasitism risk. The rapid expansion of natural gas extraction from the Marcellus Play in West Virginia and Pennsylvania is having a significant impact on these intact landscapes. Total surface disturbance of Marcellus operations per well pad can approach ~20 ha when the associated newly built infrastructure (e.g., access roads, pipelines, and wastewater retention ponds) is included. As a result, Marcellus development is projected to result in the deforestation of approximately 420,000 hectares, and grasslands will also be modified.

Researchers with the USGS Pennsylvania Cooperative Fish and Wildlife Research Unit recognized a need to quantify the relationship between bird populations and Marcellus development across Pennsylvania and West Virginia. However, there is a lack of information on impacts to avian populations largely due to the challenges of accurately measuring habitat-specific disturbance. It is estimated that 90 percent of Marcellus development occurs on privately owned land. In addition, quantifying the landscape changes associated with natural gas development requires visual examination of aerial photography over multiple years, because Marcellus gas well data available from state governments do not provide information about the size or configuration of these changes. Finally, changes to the extent and configuration of forests and grasslands are simultaneously occurring from causes other than natural gas-related activities.

The North American Breeding Bird Survey (BBS) is a long-term avian monitoring program that uses citizen science data to monitor the trends of breeding bird populations in North America. Due to its history and spatial configuration of sampling routes, the BBS could be used as an early indicator of the effects of habitat loss stemming from Marcellus-related landscape changes on breeding bird populations. The Pennsylvania CRU identified 10 interior (i.e., core) forest (e.g., Pileated Woodpecker [Dryocopus pileatus] and Veery [Catharus fuscescens]) and nine grassland (e.g., Savannah Sparrow [Passerculus sandwichensis] and Eastern Meadowlark [Sturnella magna]) bird species they hypothesized would be adversely affected by Marcellus-related activities.

Researchers used National Land Cover Data (NLCD) and semi-annual aerial photography to quantify the growth of Marcellus-related landscape changes within 250 m of 73 BBS routes. A Bayesian hierarchical framework was used to estimate the effects of this Marcellus development on the populations of those 19 bird species over the course of 11 years (2001-2011). Marcellus-related development was first observed along a BBS route in 2006, but by 2011 29 percent of BBS routes had lost interior forest and grassland habitat to Marcellus development. Approximately 15-20 percent of the development occurred in interior forest and 25-30 percent occurred in grasslands. Habitat loss from Marcellus development increased almost exponentially, and Marcellus development was responsible for approximately 20 percent of the forest loss that was observed adjacent to BBS routes from 2001-2011.

Currently, the CRU is fine-tuning forecast models to predict interior forest and grassland loss due to Marcellus-related activities over the next 20 years. These forecast models will be used to estimate the consequences of Marcellus natural gas development on bird populations in Appalachia.

The ONB features articles from Cooperative Fish and Wildlife Research Units across the country. Working with key cooperators, including WMI, Units are leading exciting, new fish and wildlife research projects that we believe our readers will appreciate reading about. This article was written by Jason Hill, past post-doc at the USGS Pennsylvania Cooperative Fish and Wildlife Research Unit and current post-doc at the Vermont Center for Ecosystem Studies in Norwich, Vermont. The principal investigator at the USGS Pennsylvania Cooperative Fish and Wildlife Research Unit is Duane Diefenbach and John Sauer at the USGS Patuxent Wildlife Research Center is also involved.