Defenders Magazine

Wild Life: Frogs Not Ready for Roundup

Frogs Not Ready for Roundup

Homeowners who care about wildlife may want to think twice before applying a common household herbicide.

According to a recent study, the world’s most commonly used herbicide, Monsanto’s Roundup, kills full-grown frogs and is deadly to tadpoles at lower concentrations than previously tested.

The study found that even when applied at one-third the maximum concentrations expected in nature, Roundup still killed up to 71 percent of tadpoles in outdoor tanks. After exposure to the maximum concentrations, nearly all the tadpoles from three different species died. Results were published in the August 1 issue of the scientific journal Ecological Applications.

The researchers also discovered that Roundup Weed and Grass Killer killed more than three-quarters of tested frogs after only one day.

“The most striking result from the experiments was that a chemical designed to kill plants killed 98 percent of all tadpoles within three weeks and 79 percent of all frogs within one day," says Rick Relyea, a biologist at the University of Pittsburgh and lead author of the study.

According to another study published recently in Environmental Health Perspectives, Roundup may also cause reproductive damage in humans. Other studies point to increased risks of contracting non-Hodgkin’s lymphoma and other cancers, according to the Pesticide Action Network.

“These results suggest that homeowners should carefully weigh the weed control benefits of Roundup against the environmental cost of spraying an herbicide that is highly toxic to amphibians," says Relyea.

Hot Times for Elephants

How do you stop a hungry six-ton animal from eating your crops? For farmers in Africa’s Zambezi Valley, the secret is in the sauce.

An African group, the Elephant Pepper Development Trust, is using chili peppers to keep elephants, buffalo and other animals from raiding ranches and uprooting crops. The group (with help from the U.S.-based Wildlife Conservation Society) is promoting chilies both as a protective buffer crop around fields of maize, sorghum and millet, and as an ingredient in sprays and pastes to drive away animals. The active ingredient from the peppers, capsaicin, is mixed with axle grease and spread on string fences around fields that elephants probe with their trunks. The farmers also mix chilies with elephant dung, dry it and then burn it—which, as you can imagine, gives out an acrid smoke.

It turns out that it works. The otherwise-imposing elephants apparently have delicate noses—they can’t take their sauce. For farmers in the Zambezi Valley (which straddles the borders of Zimbabwe and Zambia), who can’t usually afford to purchase electric fences and other expensive deterrents, the spreading of hot sauce is making good economic and ecological sense.

Finding proactive ways to prevent wildlife from consuming crops benefits locals directly and keeps them from calling for the removal of elephants and other wildlife. The peppers also have other uses: bottled hot sauces, jams and relishes made from the chilies are sold to raise money for more chili-growing and wildlife-thwarting projects.

“To have an impact on wildlife conservation you must also address the underlying causes of this conflict," says Loki Osborn, project director for the trust. “These farmers are very poor; addressing issues of crop loss to wildlife and providing a new and lucrative cash crop gives them a chance to improve their livelihood."

Singers Learn to Wing It

It’s a bird. It’s a cricket. It’s a club-winged manakin. True, it’s not the normal progression of “bird, plane and Superman," but then again this isn’t your average bird.

According to new research, the male club-winged manakin is the first example of a vertebrate making courtship music by using built-in scrapers on its wings—like crickets and other insects. For years, researchers were unable to determine what made the Ecuadorian birds tick. But in a study published recently in Science magazine, scientists discovered the birds’ unique abilities using high-speed cameras.

It turns out that this species of manakin has a unique feather on each wing that has ridges along its edges. It also has proportionally huge muscles that it uses to flap its wings at a rate of more than 100 times per second (compared to hummingbirds, which average about 50 times per second). At those speeds, the ridged feather rakes across the wing tips of other feathers and creates a “tick, tick, ting" sound that can be heard from dozens of yards away.

Charles Darwin was fascinated with the manakin family, and used them to explain his concept of sexual selection. His theory was that the feather sounds made by the male manakins were driven by the females’ mating choices.

Like a crooner serenading an audience of one, the male club-winged manakin backs into the female “wing singing" in her face. The complexity of the bird’s noise-making has but one purpose—to woo females.

“There’s tons of competition and the males have to stand out," says Kimberly Bostwick, a curator at Cornell University’s Museum of Vertebrates, and one of the authors of the study. “Their wings are used in ways like no other vertebrate, and ultimately it’s all a response to female choice. The club-winged manakins expand our ideas of what birds are capable of."

Monarchs Finding Their Way

Imagine waking up one morning with an irresistible urge to visit your great-great-grandparents’ winter home. The problem: it’s 2,000 miles away in an unfamiliar country, your ancestors left no address and you have no map. How do you find your way?

This is the challenge facing millions of monarch butterflies each fall as they head from summer habitats in the United States and Canada to wintering grounds in central Mexico. Scientists have wondered for years how insects weighing only a fraction of an ounce can navigate long distances over unknown terrain. But now they think they’ve solved the puzzle: special sensors in the butterflies’ eyes, along with an internal clock, that together form a crude compass.

Researchers recently tested the butterflies in a flight simulator and found that the insects flew toward an ultraviolet light source. The sun is the largest natural source of ultraviolet light, but following it blindly would lead butterflies on a fruitless east-west journey each day. Exploring further, the scientists found that the ultraviolet sensors in the butterflies’ eyes connected with the brain center that regulates sleep-wake cycles—the ‘circadian clock.’ This internal clock allows the insects to make adjustments for the sun’s position based on the time of day, enabling them to use the sun as a compass to guide them south.

Understanding how monarchs navigate may help conservationists protect them, says Steven Reppert of the University of Massachusetts Medical School, who led the study. In addition, he says, “understanding more about the fundamental mechanisms of the circadian clock can tell us more about how the human brain works."