Muskrats, Nature’s Unsung Restorers: How Their Underwater Nibbling Cuts Invasive Cattails by 71%

Muskrats help restore Great Lakes wetlands by cutting invasive cattails

With precise underwater nibbling, muskrats — large, semi-aquatic rodents more closely related to voles and hamsters than to beavers — are emerging as important allies in restoring degraded wetlands across the Great Lakes region. Their habit of cutting cattail stems below the waterline weakens invasive stands, opens the vegetation into a patchwork of different heights, and creates habitat for fish, birds, amphibians and invertebrates.

How muskrats change vegetation

Muskrats sever the underwater portion of cattail stems, removing the plant's "snorkel" and preventing atmospheric oxygen from reaching the roots. In dense stands of invasive cattails, this behavior produces small openings that allow shorter native plants and a diversity of species to recolonize.

"One of the first things that happens is the cattail comes in, outcompetes the very diverse community of native plants," said Shane Lishawa of Loyola University Chicago. "That prevents not only plants, but aquatic organisms — fish, invertebrates — and then also birds and amphibians from accessing and utilizing these wetlands that are critical for biodiversity across the whole region."

Invasive cattails and the study findings

Narrowleaf cattail (Typha angustifolia) arrived in North America in the 19th century in the dry ballast of European ships. Where it overlaps with the native broadleaf cattail, they hybridize to form Typha x glauca. Both narrowleaf and the hybrid are aggressive invaders that can form tall, continuous stands, reducing light and habitat complexity.

Working with partners from the Sault Ste. Marie Tribe of Chippewa Indians and the University of Connecticut, Lishawa and colleagues collected field data in a freshwater marsh linking the Munuscong River with the St. Marys River (between lakes Superior and Huron). They found that where muskrats were present, invasive hybrid cattail cover was reduced by 71% compared with areas without muskrats. The loss of tall cattails also reduced cover of European frogbit, another nonnative plant that thrives within dense cattail stands.

Cultural context

The common muskrat — Wazhashkin in Ojibwe — appears in Great Lakes Ojibwe creation stories. In one tale, the muskrat dives after the last bit of earth after the Great Flood and, though it dies in the effort, its action helps form Turtle Island (North America). The researchers note the symbolic parallel between that sacrifice and the muskrat's role in creating habitat for other organisms.

Mimicking muskrats: a management tool

Because muskrat populations are missing from many wetlands — and have declined in parts of the United States in recent decades — the team experimented with a human management technique that mimicked muskrat cutting by mowing cattails below the waterline. In the study sites, this approach produced similar reductions in invasive cattail cover, suggesting a practicable tool for managers where muskrats are absent.

"There might be circumstances where you would like to see the effects of this organism, but you don't have them there to work with," Lishawa said. The researchers also suggested the possibility of relocating muskrats from nuisance sites to wetlands where they could aid restoration, but stressed that any translocation would require careful, site-by-site evaluation to assess ecological risks and benefits.

Policy and conservation context

Wetland loss and degradation across the Great Lakes have been extensive: coastal and inland wetlands once covered more than 1 million acres in the region, and many surviving wetlands are degraded by pollution, development and invasive species. In Illinois, for example, as much as 90% of the state's original marshes and swamps have been lost to urbanization and agriculture.

The legal framework for wetland protection has also shifted: after the 2023 U.S. Supreme Court decision in Sackett v. EPA, some inland wetlands lost federal Clean Water Act protections when they lacked a "continuous surface connection" to permanent waters. A University of Illinois analysis estimated that roughly 72% of remaining wetlands in the state are no longer covered by the federal Clean Water Act following the ruling, complicating restoration and conservation efforts.

Next steps

Lishawa and colleagues have organized "Team Typha" to study how other organisms respond to systematic cattail removal — whether driven by muskrats or by human managers imitating their cutting. The team emphasizes the need for further research to evaluate ecological outcomes across species, seasons and wetland types before recommending large-scale implementation.

Bottom line: Muskrats can be effective, low-tech partners in wetland restoration, and where they are absent, targeted below-water mowing may replicate many of their beneficial effects. Both approaches merit additional, careful study as part of broader efforts to conserve and restore Great Lakes wetlands.