Demography of Louisiana Waterthrush in Response to Shale Gas Development in the Central Appalachians

Cooperative Research Unit Corner

Demography of Louisiana Waterthrush in Response to Shale Gas Development in the Central Appalachians

Extensive development of the Marcellus-Utica shale gas basin has led to concerns about environmental impacts. In response, recent research efforts through the USGS West Virginia Cooperative Fish and Wildlife Research Unit (WV Unit) have examined how unconventional shale gas development affects bird communities. One study focused on the Louisiana Waterthrush, a species of conservation concern due to its specialized habitat along forested headwater streams.

Waterthrush

Waterthrush are nicknamed the “feathered trout” since they feed primarily on aquatic insect prey and share many sensitivities to environmental impacts as trout. Many of the forested stream ecosystems in which the waterthrush primarily breed have rapidly undergone unconventional shale gas development, particularly in the Marcellus-Utica shale region. Much of the core breeding range where waterthrush reach their highest abundances also overlaps this region.

The WV Unit initiated research on Louisiana Waterthrush in 2009 when shale gas development began at their study area. Wildlife with specialized habitat needs that overlap forested areas undergoing shale gas development may be the most vulnerable to disturbance, which made the waterthrush an ideal organism to assess potential demographic consequences from shale gas development. Over a six-year period, researchers examined how increased shale gas development influenced waterthrush demography.

Waterthrush are resilient to moderate changes in the environment and can compensate for disturbance on streams by shifting their territories to forage in undisturbed sections of streams if available. However, once a certain disturbance threshold is reached, mechanisms used to adapt to disturbance appear to no longer be reliable.

Data collected suggest a decline in waterthrush site quality as shale gas development increased, despite relatively small site-wide forest loss in the predominately forested watershed. This study indicated that it does not take much disturbance in the ecosystem to affect wildlife demography and reproductive success. By identifying how variability in riparian habitat quality contributes to population surpluses or deficits, this research provides needed information for long-term conservation planning in forested landscapes undergoing development including siting guidelines for shale gas development to minimize risk to ecological resources.

The WV Unit’s research documented riparian habitat quality was negatively related to the amount of each territory disturbed by shale gas development. Territory lengths increased while territory densities decreased along streams, likely because of decreasing riparian habitat quality. After accounting for environmental factors, shale gas development also had negative effects on nest survival and reproductive success. The number of fledglings produced was lower in areas disturbed by shale gas, suggesting these disturbed areas cannot produce enough fledglings to offset adult mortality.

Waterthrush were negatively affected by changes in the aquatic prey community from shale gas development at the nest, territory, and watershed level. Riparian habitat quality assessment scores were positively linked to aquatic prey, where increased riparian habitat quality scores meant increased aquatic prey metrics. Therefore, decreased riparian habitat quality from shale gas disturbance decreased foraging resources. Additionally, site fidelity and adult apparent survival decreased over the duration of the study. Females in shale gas disturbed areas had a higher number of breeding attempts. Potential conflicts were identified between factors that influence adult survival and site fidelity may affect long-term population persistence.

Shale gas wells in the Marcellus-Utica shale region are commonly within 100-300 m of stream channels, and even closer for headwater drainage areas. The study suggests that fracking water spills, increased sediment loads, pollutants, and erosion from being too close to stream resources could be minimized with setbacks from streams and not building on steep grades.

The WV Unit’s study demonstrates how a moderately sensitive species such as the waterthrush can serve as a sentinel of overall ecosystem health and complements other waterthrush studies completed by the WV Unit.

Part of the WV Unit’s research was published in The Condor, and led to Mack Frantz being awarded the BioOne Ambassador Award. This award recognizes early-career professionals that effectively communicate important findings to the public.

Additional WV Coop Unit studies referenced:

https://doi.org/10.1371/journal.pone.0206077

https://bioone.org/journals/The-Wilson-Journal-of-Ornithology/volume-131/issue-1/18-6/Louisiana-Waterthrush-Parkesia-motacilla-survival-and-site-fidelity-in-an/10.1676/18-6.short

https://doi.org/10.3996/092015-JFWM-084

The ONB features articles from Cooperative Fish and Wildlife Research Units across the country. The Units are leading exciting, new fish and wildlife research projects that we believe our readers will appreciate reading about. Mack Frantz is a PhD candidate at the USGS West Virginia Cooperative Fish and Wildlife Research Unit at West Virginia University/Division of Forestry and Natural Resources, mwfrantz@mix.wvu.edu.

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Photo Credit
USGS West Virginia Cooperative Fish and Wildlife Research Unit
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July 15, 2019