Plateau pikas labeled as pests can actually help livestock gain more weight by keeping poisonous weeds from taking over valuable grazing plants.<\/p>\n
High on the grasslands of the Qinghai-Tibetan Plateau in western China, herders have spent decades trying to wipe out a small burrowing animal called the plateau pika. <\/p>\n
It competes with grazing yaks for food, the thinking has always gone, and poisoning campaigns have targeted the animal for years.<\/p>\n
New research turns that story around: at the right numbers, the same pest herders want gone can help yaks put on more weight.<\/p>\n
The two animals don\u2019t fight over the same food nearly as often as people assume. Pikas favor broad-leaved weeds, while yaks stick mostly to grasses and sedges.<\/p>\n
One of the weeds pikas cut down without eating a single bite of it happens to be a plant that can choke out the grass yaks need most.<\/p>\n
No competition for food<\/p>\n
Zhiwei Zhong is an ecologist at the Northeast Institute of Geography and Agroecology<\/a>, part of the Chinese Academy of Sciences in Changchun. <\/p>\n He wanted to know whether that competition was as real as everyone assumed.<\/p>\n \u201cIn rangelands and other less productive ecosystems, small mammals<\/a> are often considered pests because their population outbreaks can lead to competition with livestock for food,\u201d Zhong said. <\/p>\n \u201cHowever, it remains unclear whether their competitive effects on livestock diminish or even help livestock<\/a> growth when their numbers are at lower, non-outbreak levels.\u201d<\/p>\n Zhong\u2019s team studied a grazing meadow in Menyuan County, in Qinghai province, at an elevation of about 10,500 feet (3,200 meters). <\/p>\n Plateau pikas there very frequently clipped down a tall, poisonous weed called Stellera chamaejasme, known in the scientific literature as wolf poison, but they almost never ate it.<\/p>\n Yaks grazed mostly on grasses and sedges instead. Wherever pika burrows were thick on the ground, wolf poison thinned out, and wherever the weed thinned, yak activity picked back up.<\/p>\n Remove pikas, and poison weeds spread<\/p>\n To test what the survey hinted at, Zhong\u2019s team fenced off 16 plots on the same meadow, each about 490 feet (150 meters) on a side. <\/p>\n Some plots kept their pikas; in others, the animals were trapped out every two weeks. <\/p>\n Some plots kept wolf poison standing; in others, it was clipped down every month, mimicking how a pika would trim it.<\/p>\n Across parts of the plateau, toxic weeds spread as grazing pressure builds up, so the question wasn\u2019t an idle one. <\/p>\n Over two growing seasons, from June through August in 2022 and 2023, the plots without pikas told a clear story.<\/p>\n Wolf poison\u2019s cover roughly doubled compared with plots where pikas stayed. Grass cover in those pika-free plots fell by about half, and sedge cover slipped by about 15%. <\/p>\n The grasses and sedges that survived were also less nutritious, carrying about 14% less crude protein than the same plants growing where pikas remained.<\/p>\n Thinner grass meant less efficient yaks<\/p>\n Yaks noticed the difference. Watching each animal graze for six two-hour stretches every month, the researchers counted how often the yaks bit into plants and how many bites they managed per step.<\/p>\n Without pikas around, yaks bit into sedges about a third less often and managed less than half as many sedge bites per step. Their grass bite rate fell by close to 30%, with a similar drop in grass bites per step.<\/p>\n Eating less added up fast. Yaks in the pika-free plots gained 42% less weight per day than yaks grazing alongside pikas, as long as wolf poison was still standing. <\/p>\n Take the weed away too, and pikas made almost no difference at all, a sign that the whole benefit comes from that one plant.<\/p>\n Bingbo Ni, an environmental researcher at the same institute as Zhong, explained the mechanism. <\/p>\n With fewer poisonous plants<\/a> crowding the ground, he said, grasses and sedges no longer had to fight for light, water, and soil nutrients. They grew back thicker and richer in protein instead.<\/p>\n Helping turned to harm at higher densities<\/p>\n The benefit wasn\u2019t open-ended. Yak weight gain rose alongside pika numbers up to about 81 active burrows per acre (200 per hectare).<\/p>\n Past that point, more pikas hurt the yaks instead of helping them. Above about 162 burrows per acre (400 per hectare), the animals began competing rather than helping.<\/p>\n That\u2019s close to the outbreak densities, sometimes exceeding 200 burrows per acre (500 per hectare), that first got pikas branded as pests worth poisoning.<\/p>\n Zhong said the stakes reach well beyond one meadow. <\/p>\n \u201cLivestock grazing<\/a> currently uses around 77% of global agricultural land and sustains billions of people worldwide,\u201d he said. <\/p>\n \u201cA critical assessment of small mammals\u2019 impacts on livestock production is therefore urgently needed to guide management for both production and biodiversity conservation.\u201d<\/p>\n Implications for other regions<\/p>\n Zhibin Zhang, a professor at Hainan University\u2019s School of Ecology who worked on the study, said the same balance could guide rangeland management well beyond this one plateau.<\/p>\n Small animals often have an outsized say in how rangelands behave. Prairie dogs<\/a> on the American plains reshape grazing land for cattle in similar ways. <\/p>\n American pikas in the Rocky Mountains face pressures of their own as mountain habitats shift.<\/p>\n Ecologists call animals like these keystone species<\/a>: small in number, outsized in effect.<\/p>\n What happens once summer ends?<\/p>\n Zhong\u2019s team watched pikas and yaks graze together only during the growing season, from June to August, when food is most plentiful. <\/p>\n Whether the same benefit holds up in leaner months, when autumn and winter cut into the grass supply, is still an open question.<\/p>\n The team also worked at a fairly low elevation for the Qinghai-Tibetan Plateau. Wolf poison thins out above about 13,100 feet (4,000 meters), where other, milder toxic plants take its place.<\/p>\n Nobody yet knows whether pikas would do the same favor for yaks grazing among those weeds. It\u2019s also unclear whether the same trade-off would hold for the sheep and goats that share this land.<\/p>\n The full study was published in the journal eLife<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Plateau pikas labeled as pests can actually help livestock gain more weight by keeping poisonous weeds from taking…\n","protected":false},"author":2,"featured_media":622500,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[61,60,82,263],"class_list":["post-622499","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-ie","tag-ireland","tag-science","tag-wildlife"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/622499","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=622499"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/622499\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/622500"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=622499"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=622499"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=622499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}