by Mary O'Brien, Utah Forests Program Director
The Colorado Plateau is far from arctic, but 12 particular plants, animals, and ecosystems represent the tip of a species “iceberg” challenged by excessive livestock grazing.
Artist Heidi Snyder has rendered all 12 in good health, as we love to see them, because we need to remember what we’re aiming for with wiser grazing decisions.
In the last of six stories that have described how livestock grazing poses difficulties for Colorado Plateau species and habitats, we will consider the interaction of beavers, boreal toads, and grazing. The five earlier stories have featured hummingbirds and sage grouse, wolves and aspen, cutthroat trout and biological soil crusts, bunchgrasses and harrier eggs, and springs and a threatened plant, Last Chance Townsendia.
A wet beaver in early spring is observed near its dam among willow, aspen, and cottonwood.
Beaver (Castor canadensis) build leaky dams across shallow streams and creeks, and that particular marriage of North America’s largest rodent and water brings untold benefits to the Colorado Plateau. Beaver build their dams to create at least 2.5 feet of water in which to move, forage, and raise young safe from predators like bears, coyotes, cougars, fishers, lynx, eagles, and owls.
These dams transform shallow, narrow streams into deep ponds–incredible resources in the arid West. The benefits of these beaver dams are many, including creation of pond and wetland habitats and food webs for native trout, muskrat, voles, shorebirds, cavity-nesting birds, deer, raptors, and more. Beaver dams also raise the streambed level by capturing sediment, which allows water to replenish the adjacent floodplains. Leaked water subirrigates the valley below the dam, and the dams are physical roadbumps that reduce flood force which could otherwise gouge the stream. And more.
And what are these miracle dams built of? Wood, often stripped by beaver of its bark, for food. Beavers’ favored food is the willow family–cottonwood, aspen, or willow—that has its own particular skill: resprouting after being eaten. It’s a great match: beaver expand wetland areas that, in turn, grow more of the willow family, and the willow family provides renewable food and construction materials for the beavers’ dams and lodges.
Those willow family sprouts, however, are also favorite foods of cattle, elk, deer, and sheep. And here the conflict arises: Riparian areas are the favored hangout of cattle, for shade, water, and…willow, cottonwood and aspen. And though these plants can sprout back after being eaten, they do require rest from being consumed in order to regrow. Aspen and cottonwood need their main stem to grow above browse height, and willow need to retain a majority of their multiple stems. Thus, cattle can eat our water-master beavers out of house and home.
A boreal toad pauses amid its favored aquatic habitat: vegetation rooted at the water’s edge.
When a boreal toad (Anaxyrus boreas boreas) female mates in the still water at the edge of a pond and then anchors her egg strands by winding them around the vegetation emerging from the water, she probably isn’t aware that beavers likely made her pond.
On the Colorado Plateau, boreal toads live at higher elevations (above 8,000’) and mostly on three southern Utah Mountains (Monroe, Boulder, and Thousand Lakes) and the Paunsaugunt (Paiute for “place or home of beavers”) Plateau. You can identify boreal toads in Utah by their elevation, the white stripe down their back, and irregular warts, which, like a fingerprint, can be used to track individuals year to year.
Although boreal toads live as far north as Alaska, the southeastern populations (including those in Utah) are currently being considered for listing under the Endangered Species Act. The largest current threat to boreal toads, and amphibian populations throughout the world, is chytrid fungus, which causes their skin to thicken, preventing them from drinking water and absorbing salts through their skin. But absence of boreal toad habitat (especially beaver ponds) only adds habitat loss to injury.
Since boreal toad reproduction is so tightly linked with higher-elevation beaver ponds, and since beaver are so tightly linked with abundant willow, cottonwood, and aspen, and since cattle in particular (but also elk) spend so much time eating in willow, cottonwood, and aspen stands, we begin to sense just how indirectly, but effectively, excessive grazing can interfere with species and habitats we know and love on the Colorado Plateau.
The 12 Colorado Plateau species and habitats that have been carefully painted by Heidi Snyder are just the tip of the species “iceberg” challenged by excessive grazing. The reform of public lands grazing is both necessary and long, long overdue. Your support is essential.