These Sleepy Lizards Are Waking People Up to the Dangers of Farm Pollution
The shingleback lizard, or “sleepy lizard,” as it’s known in Australia, may be slow moving, but it could be one of the first animals to feel the effects of agricultural pesticides.
That’s according to a new study showing that sleepy lizards, and similar indicator species around the world, could provide advanced warning of the impact of agricultural chemicals on plants, people, and wildlife.
Two populations of lizards were monitored: one near an agriculture-intense region of southern Australia and one living in undeveloped rangelands.
The result? More than half the farm lizards were found to be anemic, lacking a sufficient number of red blood cells. Scientists found no signs of anemia in the rangeland lizards.
So are the farm-based lizards not getting enough iron in their diet? Not exactly. Instead, the fertilizers, weed killers, and insecticides in the agricultural environment are most likely the cause of anemia, said David Phalen, an associate professor at the University of Sydney and the coauthor of the study, which was published in the journal Royal Society Open Science.
“These lizards were exposed to a large range of chemicals, including herbicides, insecticides, and rodenticides,” Phalen said. But because the animals were studied in their natural habitat, pinpointing which chemical is causing anemia in the lizards wasn’t possible.
One probable candidate, Phalen said, is zinc phosphide, found in mouse baits that were in wide use during the study.
“Sleepy lizards are omnivores and could have eaten either the baits or poisoned mice,” Phalen said.
No matter which poison caused the disease, the research points to the importance of identifying particular species that can sound the alarm on environmental health.
“Around the world, any sedentary reptile could be a potential indicator species,” Phalen said.
In the United States, he said, box turtles could be a good species for monitoring exposure to farm pollution, while a red-eared slider—a water turtle—could be used to examine the effect of chemical exposure in freshwater environments.
“The fact this species is being affected by chemicals means other wildlife, livestock, and even humans sharing the same environment may be affected,” Phalen said, “and it suggests the health of other reptiles may also indicate the overall health of the environment.”