Groundbreaking beaver study finds more dams on private land
By Bryce Dix
June 6, 2025 at 2:03 PM MDT
The results of a first-of-its-kind aerial survey of beaver dams in New Mexico, released this week, reveal a stark contrast between the northern and southern parts of the state.
A large share of those dams are located on private land — underscoring the role of landowners in habitat conservation.
Researchers from Utah State University, hired by the conservation group Defenders of Wildlife, mapped just over 4,700 beaver dams across more than 13,000 miles of New Mexico’s perennial — or year-round — streams in 2020.
“The first surprise was how few beaver dams we had in southern New Mexico, specifically the Gila and the Sacramentos,” said Peggy Darr, lead of the Defenders of Wildlife project. “And we don't know the exact cause.”
Darr said there are a couple of reasons why this might be — such as cattle and elk overgrazing or worsening drought conditions. But that’s not all that surprised her.
“There were more beaver dams on private land than on public land, which some of us weren't expecting,” Darr said.
The survey found over half of the observed statewide dams are in just 3 northern watersheds: the Upper Rio Grande, Rio Chama, and Cimarron.
Beaver dam locations based on 2020 NAIP imagery-based New Mexico statewide beaver dam census by HUC8 watershed. New Mexico consists of 85 HUC8s with 33 entirely within the state and 52 with portions in surrounding states. (1014x1252, AR: 0.8099041533546326)
Darr told KUNM it’s difficult to speculate on why beavers favor private land, though she stresses that collaboration between the state, conservationists, and private landowners is important to keep New Mexico’s beaver population healthy.
That could include fencing off trees and vegetation to prevent beavers from gnawing them, or building “flow devices” to control a beaver pond’s water level and prevent unwanted flooding of nearby crop fields or housing.
“That allows the beavers to still flourish and be safe,” Darr said.
While the survey provides a very rough estimate of the state’s population, beavers tend to live in small groups – which makes it nearly impossible to survey accurately. The census also doesn’t account for burrowing “bank” beavers that don’t build dams in large rivers, like those found along southern parts of the Rio Grande.
In fact, beavers are increasingly hailed as ecological superheros. Their dams help raise water tables by acting like a sponge during rainy periods. Similarly, they reduce wildfire risk and help prevent flash flood damage by slowing the movement of water across the landscape.
Beaver ponds also promote the growth of a special type of bacteria that naturally filters harmful nitrates from water.
These potential ecological benefits of the beaver aren’t going unnoticed. During this year’s legislative session, lawmakers set aside $1.5 million specifically for conserving and restoring beaver habitat.
New Mexico labels the beaver as a “species of greatest conservation need” because it has an overwhelming positive effect on the state’s growing list of endangered and imperiled species.
A large share of those dams are located on private land — underscoring the role of landowners in habitat conservation.
Researchers from Utah State University, hired by the conservation group Defenders of Wildlife, mapped just over 4,700 beaver dams across more than 13,000 miles of New Mexico’s perennial — or year-round — streams in 2020.
“The first surprise was how few beaver dams we had in southern New Mexico, specifically the Gila and the Sacramentos,” said Peggy Darr, lead of the Defenders of Wildlife project. “And we don't know the exact cause.”
Darr said there are a couple of reasons why this might be — such as cattle and elk overgrazing or worsening drought conditions. But that’s not all that surprised her.
“There were more beaver dams on private land than on public land, which some of us weren't expecting,” Darr said.
The survey found over half of the observed statewide dams are in just 3 northern watersheds: the Upper Rio Grande, Rio Chama, and Cimarron.
Beaver dam locations based on 2020 NAIP imagery-based New Mexico statewide beaver dam census by HUC8 watershed. New Mexico consists of 85 HUC8s with 33 entirely within the state and 52 with portions in surrounding states. (1014x1252, AR: 0.8099041533546326)
Darr told KUNM it’s difficult to speculate on why beavers favor private land, though she stresses that collaboration between the state, conservationists, and private landowners is important to keep New Mexico’s beaver population healthy.
That could include fencing off trees and vegetation to prevent beavers from gnawing them, or building “flow devices” to control a beaver pond’s water level and prevent unwanted flooding of nearby crop fields or housing.
“That allows the beavers to still flourish and be safe,” Darr said.
While the survey provides a very rough estimate of the state’s population, beavers tend to live in small groups – which makes it nearly impossible to survey accurately. The census also doesn’t account for burrowing “bank” beavers that don’t build dams in large rivers, like those found along southern parts of the Rio Grande.
In fact, beavers are increasingly hailed as ecological superheros. Their dams help raise water tables by acting like a sponge during rainy periods. Similarly, they reduce wildfire risk and help prevent flash flood damage by slowing the movement of water across the landscape.
Beaver ponds also promote the growth of a special type of bacteria that naturally filters harmful nitrates from water.
These potential ecological benefits of the beaver aren’t going unnoticed. During this year’s legislative session, lawmakers set aside $1.5 million specifically for conserving and restoring beaver habitat.
New Mexico labels the beaver as a “species of greatest conservation need” because it has an overwhelming positive effect on the state’s growing list of endangered and imperiled species.