Researchers Use AI to Predict Beavers’ Impact on Local Habitats—and Show How Humans Can Help

Across the Rockies and Great Plains, beaver dams interrupt narrow streams, slowing currents into chains of ponds that reshape channels and spread wetlands across valleys. The mud-and-stick barriers create habitat for willows and cottonwoods, sustain corridors of green vegetation long after surrounding hills have browned, and soften the force of floods.

In the West, as droughts persist and wildfires grow more frequent, those ponds serve as natural reservoirs and refuges when streams run low. Their benefits have fueled efforts to reintroduce beavers to river systems and to mimic their work with human-built structures known as beaver dam analogs (BDAs). 

While the success of those projects depends on how much water the structures will hold and how large the ponds will grow, land managers have lacked a reliable method to predict which sites would support broad wetlands and which would yield only small pools.

A new study in Communications Earth & Environment begins to answer that question. Using high-resolution aerial imagery and machine learning, the researchers mapped more than 1,200 individual beaver ponds across Colorado, Wyoming, Montana and Oregon to determine which factors best explained their size. The clearest predictor was dam length, followed by the height of nearby woody vegetation and the force of water moving downstream. Together, the three variables explained nearly three-quarters of the variation in pond size.

The results confirmed what ecologists had suspected but never quantified at scale: longer dams hold back more water. By establishing that relationship between dam length and water storage, the study equips restoration workers with tools to predict pond size in advance. 

“Based on the dams that people build, we could possibly estimate their pond area behind the dam,” said Luwen Wan, lead author of the study and a postdoctoral researcher at Stanford University. “So, we would be able to further know how much water could be stored in those ponds, and the hydrological and ecological impact.”

Although the study used summer imagery, which may have overlooked some ponds hidden beneath vegetation or altered by seasonal flow, and the climate datasets were relatively coarse, the statistical relationships remained robust across ecoregions, underscoring the central role of dam geometry and local stream conditions.

“Any advancement that we can make in understanding the drivers behind where and when and how big and how much beavers are going to build is really valuable, and it’s particularly valuable when we’re looking at beaver restoration and reintroduction,” said Jessie Moravek, a postdoctoral researcher at the University of Minnesota’s St. Anthony Falls Laboratory, who was not involved in the study. “It tells us what tools we need to be looking at on a local scale to understand how beavers are going to make a local impact.”

For the animals, dam building is a matter of survival. Larger ponds protect beavers from predators and allow them to move more safely between food sources, while deeper water insulates their lodges from winter ice. 

But the ecological consequences extend beyond single colonies, with pond size affecting how much water is stored in the landscape, how far floodwaters spread and how much habitat is created for plants and other animals.

“A beaver dam is built to store water and give the beaver a bigger backyard,” said Cherie Westbrook, professor of ecohydrology at the University of Saskatchewan and associate director at the school’s Center for Hydrology, who was not involved in the study. “If you are storing more water in the landscape, you’re automatically protecting against drought and also the spread of wildfire.”

Until now, most tools available to land managers have focused on estimating how many dams a stream might support, rather than the amount of water those dams would hold. But BDA installation is quickly growing in popularity across regions, sometimes faster than science has kept up. 

“There’s just a lot of BDAs being put up, and that’s because the guidance from the scientists is missing on how many we really need, where they’re most effective, and why they’re most effective,” said Westbrook. “This particular study really gets at where and why BDAs and dams can be quite effective in producing the kinds of hydrological results that are desirable.”

The study also weighed the role of climate against local geomorphology and hydrology. Precipitation and temperature were weaker predictors than valley shape, stream power, and vegetation—a result Wan attributed in part to the mismatch between coarse climate data and the fine scale of ponds.

“The resolution of the data was coarse and might be problematic, but I have long thought and long observed that climate is much less important than the geomorphic setting,” said Westbrook, who has studied beavers on several continents. “You only have so much physical space that certainly can be flooded by beaver dams. Beavers can only build a dam so large.”

This climate adaptability is evident in beavers’ range, which extends from Canada’s boreal forests to the deserts of the Southwest.

“Beavers are really adaptable,” said Moravek. “Moving forward in a changing climate, hopefully beavers are going to be able to adapt to that and roll with the punches a little bit, and continue to create these ecosystem engineering benefits.”

Moravek said beavers are not immune to climate pressures but can persist through droughts, floods and fires, often creating refuges that shelter their colonies and other species. “That is what makes them a powerful keystone species.”

But the same ponds that provide those benefits can also spark conflict, inundating farmland, washing out culverts, or felling trees valued by landowners.

“I think it’s very important to consider risks,” said Westbrook. “There are very real risks of implementing beavers as a nature-based solution, and they may be talked about a lot less than all of the benefits, but they are certainly equally important.”

The impacts of beaver ponds also vary widely by region, and can, in some cases, run counter to climate goals. In Alaska’s Arctic, researchers and Indigenous communities have found that expanding ponds can accelerate permafrost thaw, releasing greenhouse gases and threatening fish populations central to subsistence traditions, underscoring how beavers can worsen climate risks.

Predictive models can help managers anticipate how much area a dam might flood, thereby reducing the risk of damage to property and livelihoods. Moravek said more precise predictions of pond size and flooding potential “help you be successful with your restoration action.”

Among the study’s most surprising results was the geometric relationship between dam length and pond size: a consistent scaling pattern that held across diverse regions. Wan said she had not expected the relationship to be so clear, and that the regularity could provide a straightforward, data-backed way to approximate pond area when designing projects.

State agencies are beginning to integrate beaver management into broader water and habitat strategies. In California, wildlife officials have released animals onto tribal lands. In Colorado, restoration planning increasingly considers where beavers might thrive. By quantifying how local stream conditions influence pond size, the study provides a potential framework to make those decisions more strategic.

Researchers say the next frontiers will be temporal and subsurface: how long ponds persist before they fail, how much groundwater they store, and how networks of ponds evolve over time. Wan hopes to extend the mapping effort with artificial intelligence. Westbrook highlighted dam lifecycles—construction, collapse, abandonment and renewal—as an exciting area of research. Moravek pointed to subsurface water storage as an unsolved challenge.

Across these efforts is a shared recognition of beavers’ unique adaptability and the resilience they confer on the landscapes they inhabit.

“Beavers are a really important collaborator in adapting to a new climate future in North America and Europe,” said Moravek. “The more that we can learn to work with them effectively, the better off we’re going to be.”