Pre-construction Avian Studies & Eagle Nest Surveys

Throughout the project, TRC coordinated closely with the relevant regulatory agencies including USFWS to update them on the study design and results to facilitate more efficient project completion and streamlined project construction.



Alliant Energy

Project Location


Alliant Energy, through its Interstate Power and Light Company (IPL), has proposed the construction of two wind farms- Whispering Willow North and Whispering Willow South- located across 100 square miles of agricultural land in Franklin County, Iowa. Each facility has the capacity to site up to 225 utility scale wind turbines and generate a cumulative 500 MW.


TRC conducted on-site avian surveys and cultural assessments to support pre-construction environmental due diligence beginning in 2015 with a fatal flaw analysis.

Avian Studies

Our biologists conducted pre-construction avian studies in compliance with the Endangered Species Act, Migratory Bird Treaty Act, and the Bald and Golden Eagle Protection Act, and as recommended by the U.S. Fish and Wildlife Service (USFWS) Land-based Wind Energy Guidelines and the Eagle Conservation Plan Guidance. Our study evaluated the project for compatibility with avifauna in the area, provided information to facilitate effective design and operations decisions that will minimize impacts to avifauna. Surveys of 60-minute eagle use for bald eagles, other raptors and large birds, and 10-minute point count surveys targeted at passerines and other small birds have been conducted every month since October 2016 and will continue through September 2018.

Eagle Nest Surveys

In 2017, TRC conducted eagle nest surveys to search for and document the presence of bald eagle nests within a 10-mile buffer around the project area. Our surveyors drove all accessible roads within the project area and observed and document eagle nest presence and eagle behavior. Surveys were repeated in 2018. 

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Renewable Energy

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