‘Herbivores’ most at extinction risk: study
Leopard frog found
LOS ANGELES, Aug 6, (AP): Although scientists often worry most about the loss of the world’s predators, a comprehensive new study finds that plant-eating herbivores are the animals most at risk of extinction.
About one in four species of herbivores, 25.5%, are considered threatened, endangered or vulnerable by the International Union for Conservation of Nature (IUCN), the world’s scientific authority on extinction risk, according to a study in Wednesday’s journal Science Advances.
By comparison, 17.4% of the predators and 15.8% of omnivores were at risk, said study lead author Trisha Atwood, an ecologist at Utah State University.
Researchers analyzed data for 22,166 species of animals with backbones, including the type of animal (reptile, bird or mammal), geographic location, habitat and size. And in just about every way examined, they found plant-eaters were the most at risk, especially in forest ecosystems. “The implications for this are huge,” Atwood said. “We need to think about herbivores as being kind of the poster child of extinction.”
So instead of polar bears and tigers, think of plant-eaters like rhinos and green sea turtles, Atwood said. The last male northern white rhinoceros in the wild died in 2018, but scientists are scrambling to save the species with donor embryos.
The study focused on proportionality, not raw numbers of species at risk. There are many more predator species, so there are more vulnerable predators in total, but a larger share of herbivores are in trouble.
Scientists even examined the presumed diets of more than 2,000 species no longer alive and found that herbivores again had the highest extinction proportion.
Atwood went into the study thinking that the predators were most at risk. However, she said the data – which included land and water species, but not fish because of inadequate information – pointed clearly at herbivores.
Predators, she added, also are in trouble, but not as much as herbivores they often eat.
Extinction causes – invasive species, climate change and habitat loss – hit herbivores harder than animals with other diets, Atwood said.
Size may be part of the reason herbivores are more at risk, the ecologist said. Often, herbivores are bigger and need to eat more and require more land and their habitats are becoming smaller, she said. Predators and omnivores have wider ranges and that helps them survive.
Duke University conservation scientist Stuart Pimm, who wasn’t part of the study, said his problem with Atwood’s research is that it doesn’t take into account the immense importance of geographic range, which is key for predators.
But University of Miami biologist Mauro Galetti, who also wasn’t part of the research, said Atwood’s study is important, makes sense and “changes our biased idea that conservation projects should focus mostly on top predators.”
Inadequate
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FLAGSTAFF, Ariz: A rare frog has been found beyond its known range in the Southwest.
A US Forest Service volunteer recently photographed a Chiricahua leopard frog in an earthen stock tank near the town of Camp Verde in central Arizona, the agency said Thursday. Biologists later confirmed that at least 10 of the frogs were living there.
The aquatic frogs were thought to be only in eastern Arizona, western New Mexico and northern Mexico but historically were more widespread. The frogs’ numbers have declined because of habitat loss, disease and predators.
Audrey Owns of the Arizona Game and Fish Department said the frogs could have moved into lower elevations in Camp Verde because they were seeking protected habitat or warmer temperatures that guard them from fungal disease.
The US Fish and Wildlife Service listed the frogs as threatened in 2002. Part of the recovery efforts have included rearing the frogs in captivity and releasing them into stock tanks. A recovery team also has been supplementing water amid a prolonged drought, removing livestock, deepening stock tanks and controlling erosion.
“Large-scale and varied recovery efforts, such as those carried out in the Fossil Creek watershed, are vitally important since biologists do not know exactly which efforts will be successful, or how frogs will adapt to changes in natural conditions, such as disease and long-term drought,” said Janie Agyagos, a wildlife biologist for the Coconino National Forest’s Red Rock Ranger District.