Beaver, Boreal Toads, and Grazing

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.

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. 

So stop letting your cows graze the waterways. We would like our water to be ecoli free anyway, but it’s especially worth noting that they eat the shoots that would feed the beavers who would make the streams better. I believe this is the last in the series of 12 reasons enumerated by the Grand Canyon Trust with artist Heidi Snyder and hero Mary Obrien. This is the final of six reports on the topic and you can go here to see the others.

Heidi Snyder’s  paintings are wonderful and we are thrilled that they were commissioned to tell this story. And speaking of commissioned we’re working with the artist at Coyote Brush Studios to do an original painting of our ecosystem poster, so that we can share it far and wide without incurring copyright wrath. Tina Curiel is also doing watercolor tattoos for our beaver activity at this years festival, and I for one can’t wait.