The Unique Impact of Solar Farms on Grassland Birds

Grasshopper Sparrows lose habitat when solar panels are situated in a large grassland. © Ginny Moore on iNaturalist.

Tanks and helicopters—grassland birds can tolerate a lot of disturbance.

I’ve captured and tagged Eastern Meadowlarks and Grasshopper Sparrows on the military training grounds at Fort Riley, Kansas, while tanks rumbled past our mist nets and helicopters buzzed us. At the time, with tracer bullets flying and artillery passing overhead, it felt more like a sci-fi movie, and absurdist. 

But those lands are highly productive habitats for grassland bird species. Grasslands, after all, only exist because of disturbance. Without fire or grazing suppressing woody vegetation, grasslands quickly disappear into shrubs and then forest. Sometimes I’ve wondered whether grassland birds perceive tanks the way their ancestors once perceived herds of American Bison—large, disruptive forces that altered the landscape but left open habitat behind long after they moved on.

What grassland birds don’t tolerate well, however, is habitat loss. They are area-sensitive species—their densities increase as grasslands get larger, and they decline as fields are subdivided or interwoven with non-grassland habitat. Just as importantly, they respond to the perceived size of a field. A narrow row of trees, for example, can function like an uninviting wall, shrinking usable habitat far beyond the footprint of the trees themselves.

I saw this firsthand during my PhD work on Grasshopper and Henslow’s Sparrows, where we documented their population responses after experimentally manipulating tree densities in savanna-like grasslands.

Those same grasslands are increasingly intersecting with another force shaping Vermont’s landscape: photovoltaic (PV) solar farms. Under Vermont’s 2020 Global Warming Solutions Act, our state is legally required to reduce greenhouse gas emissions by 80% compared to 1990 levels by mid-century, and a substantial body of research supports expanding renewable energy—particularly solar—as a key part of those broader efforts. Reducing emissions remains one of the most important ways to safeguard ecosystems over the long term.

In recent years, thankfully, there has been a growing effort to make large-scale solar development less impactful on wildlife. Solar facilities can be designed to better accommodate wildlife—for example, by modifying (or eliminating) perimeter fencing to allow mammal movement and planting native vegetation instead of lawn grass to support pollinators. Taken together, these approaches reflect a genuine and welcomed attempt to reduce the ecological footprint of solar development.

But climate solutions unfold in real landscapes. In Vermont, utility-scale solar developments are often sited (i.e., placed) on low-intensity agricultural lands—hayfields and pastures—the very landscapes that support many of our remaining, dwindling grassland bird populations of Eastern Meadowlarks, Grasshopper Sparrows, and other species. As a result, conversations about “wildlife-friendly solar” can feel relatively straightforward for pollinators, but grind to a halt when someone brings up grassland birds.

The View from the Grass

From a Grasshopper Sparrow’s perspective, a solar installation within a former hayfield fundamentally changes how that space is perceived and used. Closely-spaced rows of panels, support structures, fencing, and access roads likely reduce the real and perceived openness of a field. Indeed, recent research found solar farms in the Midwest to be strongly, negatively associated with Grasshopper Sparrows, while the species that show positive relationships to solar fields tend to be less area-sensitive or not grassland obligate species, such as Chipping Sparrow and Eastern Bluebird.

Solar arrays are frequently built on open agricultural fields—the same landscapes that support many of our remaining grassland bird populations. Wikimedia Creative Commons, all rights waived.

This helps explain why design elements that are often highlighted as “bird-friendly”—such as wider panel spacing—don’t necessarily translate into usable habitat for grassland birds. For area-sensitive species, the issue is the loss of large, uninterrupted open space and the introduction of vertical structures that visually and physically fragment what was once continuous habitat.

Small Mitigation for a Large Problem

In an attempt to partially offset this grassland loss, Vermont requires developers to address impacts to grassland birds through a mitigation process. Developers are required to survey for these species during the breeding season on fields greater than 20 acres. If grassland bird species are detected, developers must mitigate for both direct (the project footprint) and indirect (the area beyond the footprint up to 50 meters) impacts. From my experience serving on Vermont’s Bird Scientific Advisory Group, which reports to the Endangered Species Committee and reviews these permit applications, developers almost always choose the mitigation option of making a direct payment to Massachusetts Audubon, for their management of the Bobolink Project within New England. The payments occur annually for the life of the solar project, and are currently $50/acre.

Developers must conduct construction work outside of the breeding season to avoid destroying nests and young, as required under the Migratory Bird Treaty Act. So, in essence, the birds themselves are protected, but not their habitat. 

Criticism of the mitigation process towards grassland birds has largely fallen on three aspects. First, the practice assumes that displaced birds can be absorbed by a shrinking number of suitable fields elsewhere. As grassland bird populations decline and grasslands themselves become rarer in Vermont, that assumption becomes increasingly unlikely. Second, solar development can replace habitat occupied by the rare Grasshopper Sparrow, for example, but there is no requirement that mitigation funds be directed toward supporting the same species elsewhere in the state. Indeed, with fewer than two dozen Grasshopper Sparrows left in Vermont, largely concentrated on two land parcels (Camp Johnson and Franklin County Airport), this would be difficult to accomplish even if required. 

Third, this mitigation framework does not distinguish between impacts to relatively common grassland birds, such as Bobolinks, and impacts to species that are already rare or state-listed, such as Upland Sandpiper and Eastern Meadowlark. As a result, habitat loss affecting Threatened and Endangered species is treated similarly to habitat loss affecting more abundant species, despite the very different conservation risks involved. 

Some adaptable bird species, such as American Robin (pictured here), may nest or forage within solar installations. Area-sensitive grassland birds, however, require larger, more open habitats than conventional solar fields typically provide. © Jill DeVito on iNaturalist

Finally, while mitigation funds support grassland bird management, the per-acre payments are not sufficient to purchase, permanently protect, or manage grassland parcels in perpetuity. In response, the mitigation process is better viewed as a partial and ephemeral offset, rather than a long-term mechanism for replacing lost grassland habitat.

Siting Solar to Protect Grassland Birds

As Vermont works to meet its climate goals, solar energy will continue to play an important role in reducing greenhouse gas emissions, but we still have much progress to make to design solar farms that are at least neutral toward grassland birds. This may mean placing greater emphasis on siting decisions and creating stronger incentives to avoid high-value grasslands and fields that support Threatened and Endangered Species. It may also involve exploring whether design elements—such as panel height, spacing, layout, or resting angle in tracking systems, plus vegetation management—can meaningfully reduce the fragmentation of grassland bird habitat. 

These challenges represent real opportunities for policymakers, landowners and developers, and conservation practitioners to co-develop and test innovative solutions, to meet both our energy needs and wildlife responsibilities. Grassland birds remind us that climate solutions involve tradeoffs that are not always easy to resolve. Clear-eyed conversations about where solar development occurs, how impacts are mitigated, and what success looks like for wildlife are essential if we hope to meet our energy goals without losing species that are already in decline. 

If you are interested in collaborating to explore or test novel approaches that could help solar development better coexist with grassland birds, please get in touch. I would welcome the conversation.

Jason Hill (he/him)

Jason is a quantitative ecologist with the Vermont Center for Ecostudies (VCE). who has been studying grassland bird populations for the last decade. Here at VCE, Jason leads research investigations into the ecology of animal migration and montane ecology, and Jason hosts the popular local science discussion series, Suds & Science.