As the U.S. Fish and Wildlife Service contemplates whether to afford the monarch butterfly protections under the Endangered Species Act, pollinator conservationists point to cattle rangeland as a potential habitat of significance for this and other insect pollinators falling dangerously close to the risk point of extinction.
Monarchs – an iconic butterfly known for its more than 3,000-mile, multi-generational annual migration from Mexico to Canada and back – has received the most attention of pollinator species status since the advent of the honey bee’s still-mysterious Colony Collapse Disorder back in 2006. Conservation groups have pushed for the butterfly’s listing as a threatened species, a decision that the FWS has until June 2019 to make.
“Endangered Species Act protection can’t come soon enough for this beautiful but beleaguered butterfly,” said Tierra Curry, senior scientist at the Center of Biological Diversity in Tucson, Ariz., in a press release. The Center is one of the major conservation groups that petitioned for the ESA listing.
Monarchs have seen an 80-percent decrease in population since 1995, blamed primarily on habitat loss. While deforestation has also reduced the species’ overwintering sites in Mexico, the center of blame has landed on agricultural activities in the Central U.S., the monarch’s primary breeding grounds and flyway. The sole food source of the monarch caterpillar, milkweed plants used to thrive in fence rows, ditches, field edges, and pastures – that is, until the price of crops in the mid-2000s led to a massive conversion of pastures to cropland, and Monsanto’s development of glyphosate revolutionized weed control in corn and soybean fields.
According to the Center, the monarch butterfly has lost 165 million acres of breeding habitat in the last 20 years – roughly a Texas-sized portion of its Central U.S. acreage. What is left of monarch caterpillar habitat is scattered in small patches.
Pollinator conservationists have developed popular initiatives to promote monarch habitat, but the challenge is that few of these milkweed plantings, like the remnants of wild milkweed patches, are sizable enough to sustain a population increase. To do this, monarchs need acres of habitat.
In addition to native milkweeds for caterpillars, the ideal habitat would also safely host the nectar-loving adult butterflies.
“A landscape with abundant flowering plants is fundamentally what we need, and we need those landscapes to be free of pesticides,” said Mace Vaughn, co-director of the Pollinator Program at the Xerces Society for Invertebrate Conservation in Portland, Ore. “Range and pasture have huge potential.”
He and other pollinator conservationists envision cattle country doubling as oases not only for monarchs, but also other butterflies, native bees, and even lesser-known pollinators like beetles, bats, and birds. Monarchs are far from the only pollinator species at risk of extinction, which also includes 140 species, or 18 percent, of North American butterflies and a quarter of North American bumblebee species.
“These observations are ongoing and worrisome,” Vaughn said.
Native range is most ideal for butterfly habitat, because it is more likely to support specific host plants used by less common species. Pastures planted to grass and legumes are more ideal for native bees in that they not only provide foraging habitat but also places to nest in overgrown, no-till areas and brush or dead trees.
However, rangeland and pastures are not without risks to pollinators. Most concerning is broad-spectrum spraying for noxious weeds or insect pests, such as grasshoppers. Broad-spectrum spraying of herbicide reduces the foraging habitat of pollinators, and insecticides kill butterflies and bees on contact. Vaughn suggests an Integrated Pest Management (IPM) approach, with any chemical applications done through targeted spraying to minimize its effect.
With IPM, pest insect management may not have to get the point of spraying, he said. Ideal pollinator habitat includes a wide diversity of range plants, which also increases the diversity of pest insect species. This increases the competition between those pest insect species, naturally reducing their overall effect on the habitat.
Management systems that promote this wide diversity of plants are those that are more intensively managed. Required features of these management systems are an avoidance of overgrazing and prevention of any grazing of eco-sensitive areas, such as riparian edges. Other management system options compatible with pollinator habitat include patch burns, range-seeding with grass and legume mixes, and rotational grazing.
“It comes down to understanding your landscape and your goals,” Vaughn said.
Managed grazing is largely customizable. One producer may heavily graze cool-season plants to reduce later competition with wildflowers. Another producer may rest his rotationally grazed paddocks an extra 10 to 20 days to maximize wildflower bloom.
Producers exploring their options can find pollinator grazing plans through the NRCS, such as in Kansas and Oklahoma. There are even incentive payments available through Wisconsin’s NRCS for dairy producers.
Especially if the monarch butterfly is listed with the ESA, these types of pollinator-friendly grazing programs are only likely to expand – but should there be concern that milkweeds carry a toxicity risk to livestock?
“With almost all milkweeds, there’s not a problem as long as you’re managing your pasture well,” Vaughn said. “Cattle will only eat milkweeds if there’s nothing else in the pasture, and they have to eat 5 to 10 percent of their body weight in milkweed to get sick.”
Milkweed toxicity is more of a risk to sheep and goats, as they don’t find the broadleaf to be as unpalatable.
Cattle may accumulate toxicity if there is a high concentration of milkweed in their hay, according to Anne Stine, a pollinator conservation specialist with the NRCS in Fort Worth, Texas. But in the pasture, cattle tend to avoid the broadleaf.
“If you’re running cattle, they have to be desperate,” Vaugh agreed. “As long as they’re not starving, they’re not eating it because of its taste.”
Certain milkweed species are more potent than others. According to Stine, the toxicity of milkweeds in the South is considerably higher than the Common Milkweed prevalent in the Northern Plains. Still,, overgrazing should be avoided in rangeland and pasture management to prevents cattle from resorting to grazing milkweed.
“With just sensible, common sense grazing management – it doesn’t have to be anything special – it’s not going to be a problem,” Vaughn said. “It’s not a critical issue.”
With this concern out of the way, and with development of pollinator-friendly grazing programs on the rise, pollinator conservationists like Stine and Vaughn are hopeful for the future of monarch habitat.
“With range management and pasture management, I can see a huge potential for hundreds of thousands of acres, if not millions of acres, of habitat,” Vaughn said.