Rats with poisonous hairdos live surprisingly sociable private lives
It’s snuggling and togetherness when the deadly, swaggering rodents have families
By Susan Milius
Crested rats don’t just chew tree bark that’s poisonous enough to kill an elephant. The rabbit-sized rodents dribble and lick the toxic drool into their long rat fluff for a weaponized hairdo. Yet these dangerous rats, which scientists assumed were loners, turn out to have a close and cuddly family life. They even purr.
Chewing on bark or other parts of East Africa’s arrow poison trees gives the rats toxic saliva to apply to specialized zones of fur. The toxins sink in to porous, easily detached hairs on the rat’s flanks. Any predator foolish enough to bite a Lophiomys imhausi gets a hairy mouthful of bitter toxins that human poachers use on arrows for hunting big game.
The rats “have the personality of something poisonous,” says ecologist Sara Weinstein, who studied them during a Smithsonian fellowship at the Mpala Research Center in Kenya. “They can run quickly if they feel like it, but they don’t typically.” The rats are more likely to jog away from trouble or stand their ground, hissing, growling and grunting.
Trapping crested rats took some experimenting, says ecologist Katrina Nyawira, who worked on the project with Weinstein before moving to Oxford Brookes University in England. “Sometimes we’d set traps for about two weeks and just get one individual and, trust me, that would be a win.”
Researchers set traps in a weird variety of locations, from remote spots in the Kenyan savanna to behind somebody’s bedroom door, Nyawira and Weinstein realized that the common success factor was access to arrow poison trees (Acokanthera schimperi).
With glossy, green leaves shaped like fat teardrops, this widespread shade tree is a cousin of the North American milkweeds that give monarch butterfly caterpillars their defensive toxins. From roots to shoots, the arrow poison tree carries potent cardenolides that can give would-be predators a heart attack.