Critters in Crisis: How Livestock Contributes to the Decline of Amphibians
Imagine cresting a small rise and looking out over an endless flat expanse of prairie. Unlike the cornfields of today, this land isn’t all one color; it is a fantastic mosaic of hues and textures, of grasses and forbs, of tussocks and pools. When the wind blows across this quilted landscape you see winks of sunlight reflecting from the water beneath the vegetation. Though the prairie looks like terra firma, it holds millions of gallons of water, just out of sight from your vantage point. You begin to descend the hill, heading down towards the inundated expanse, and your foot breaks a twig. The tiny snap echoes across the vista and like a single enormous entity a black mass of birds rises from beneath the grasses. There are more birds than your modern mind can comprehend — enough birds that they shade the earth like a thundercloud — and the sound of their wings beating in tandem is like a roll of thunder across the prairie. The birds were resting in the water, and they send droplets across the sky as they go, like a miniature storm crossing the landscape.
Entire states like Iowa and Indiana were once marshy swamplands such as the one I just described, teeming with life. These moist, rich landscapes exist now in just a fraction of their former range and diversity. In the American southwest lush desert wetlands, known as cienega were once a common sight. In the grasslands of the Midwest, water-logged “looking-glass prairies” once reflected the endless sky and provided refuge for fish, mammals, migrating birds, and millions of amphibians.
As of 2023, 41% of amphibian species are at risk of extinction. There are many reasons for the massive decline in the past several decades, and climate change causing drier winters and hotter summers is a large one. Climate change impacts only increase the devastation of the other main threats against amphibians; water management on rangelands, invasive species encroachment, lowered water tables, and livestock grazing. In Brazil, the Rustic Monkey Treefrog will soon be extinct in the wild due to the effects of cattle grazing and deforestation to make way for more cows. In my home state of Oregon, the endangered Oregon Spotted Frog is particularly vulnerable to impacts from ranching because it is a communal breeder; meaning the species will congregate in a wetland and lay eggs en masse. These massive groups of eggs, so important for a struggling species’ future, are easily trampled by cattle. The shallow waters where this aquatic species lives and breeds are drained by irrigation systems and wells. The Oregon Spotted Frog has lost 78% of its former range. Its scientific name, Rana pretiosa, means “precious frog”.
However, we are not treating our amphibian species as precious. Most western ranch operations rely on irrigated hay pastures to provide winter forage, which drains rivers, degrading riparian environments. More than 75% of the West’s wildlife species are dependent to some degree on riparian habitat. What wetlands remain in the United States enhance water quality, filter pollutants, sequester large amounts of carbon, and provide food and habitat for a vast range of species. From the endlessly stretching expanses of wetland ecosystems that the pioneers first encountered, remnant patches of wetlands are now found in pockets of riparian woodlands, or in guarded fields along highways. In my area of southern Oregon, one of the largest seasonal wetland remnants abuts the county landfill. Natural river systems and wetlands reduce flood risk by storing water and slowing water flows, and keep water table levels high, reducing the impact of droughts.
Shockingly, cattle still graze on many remnant wetlands on our public lands. Cattle change the species mosaic of a habitat by selectively eating plants that they prefer and leaving those they find distasteful, causing long-term changes in the makeup of wetland plant communities and decreasing vegetation biomass. These vegetation changes affect the insect and invertebrate communities, which in turn affects vertebrates like frogs and fish, who feed larger species like birds and mammals. Feces from cattle has a massive effect on the water column in wetlands, disrupting the sediments and increasing the nutrients in the water, leading to algae blooms and changes in water temperature. Many wetland sedge meadows where cattle historically grazed become covered in water-sucking shrubs when the cattle are removed. These shrubs invaded the landscapes when cattle disturbed the vegetation mosaic. Without the cattle there keeping them small, these invaders will spread and grow, further reducing the biodiversity and water tables of these meadows. The quick fix is to continue to graze cattle on these lands- therefore cattle are touted as a means of “restoring shrubbed wetlands.” Unfortunately, restoration is only necessary because of grazing cattle’s presence in the first place. Cattle grazing in degraded wetlands as ecological restoration is not a viable long-term solution and does nothing to restore the original plant and animal communities of these rare landscapes, or to increase their water storage capacity to pre-agricultural levels.
As I traveled across the southwest visiting National Parks and monuments in the summer of 2021, I encountered endless signs of the water crisis facing our western states. At many trailheads, signage warned that streams and creeks previously marked as water sources were now dry. Through hikers were forced to carry gallons of water in for their journeys, unable to refill their bottles on the trail. Water restrictions at campgrounds meant public showers were closed and formerly irrigated grassy gathering spaces were reduced to dust pits. Reservoirs I passed were shockingly low, the ghostly stumps of previously flooded trees visible for the first time in decades. The nights were quiet, without the choruses of frogs that I associated with summers out of doors. Unless we wish to live in a world where nights are always silent and our wetlands no longer teem with life, changes must be made to how we manage our ecosystems, before it is too late.
