The Garden of Earthly Fools

owlface5Detail
Jheronimus van Aken (c. 1450 – 1516)

 
New research published in the journal Biological Conservation finds that for every decibel of added noise, the hunting ability of saw-whet owls declines dramatically.
Their odds of detecting prey fell 8 percent per decibel, while the odds of actually striking the prey they did detect fell 5 percent per decibel.
By the time noise reached 61 decibels—a little louder than a busy restaurant—the owls completely failed to even notice nearby prey.

Lead researcher Tate Mason, education coordinator for the Peregrine Fund’s World Center for Birds of Prey, says the research was inspired by early studies into bats, which found that the flying mammals had to increase their hunting search times when flying near noisy highways.
“We wondered if other acoustically specialized predators, in particular birds, could be facing the same scenarios.”

They set out to examine the problem.
Instead of highways, though, they designed their experiment to replicate the sounds produced by natural-gas compression stations.

“Compressor stations are relatively new in the landscape,” Mason says. “They are increasing, and they run 24 hours a day, year-round.”
That gives them more impact than highways or airports, which create a lot of noise during the day but can be much quieter at night when owls tend to hunt.

Although he suspected that the birds would have impaired hunting ability, the complete failure surprised him. “The impact was more profound than I thought it would be,” he says.

Bangor University lecturer Graeme Shannon led work on a paper that synthesized research into the effects of noise on all manner of wildlife.
“These are noise levels that can readily extend hundreds of meters from an active drill rig or a busy highway,” he says, “which in effect drastically reduces the suitable habitat for animals that need to hunt.”

Mason says that’s an important aspect of his research. “The quiet places on Earth are becoming few and far between.”
Protecting those naturally quiet spaces from intrusive noise, he says, will help acoustic specialists such as saw-whet, Great Gray, and Northern Spotted owls.

“We have the ability to know ahead of time that there’s a threat out there that could be compromising owl habitat:
If we deal with that before the population declines, we can do better at conserving our wild creatures.”


http://www.audubon.org/news/human-noise-robs-owls-their-ability-hunt

The Canary

canary finch menzelAdolph Friedrich Erdmann von Menzel (1815 – 1905)

 

Did Your Shopping List Kill a Songbird?
New York Times March 30, 2008

A consumer may not be able to tell the difference but a red & blue Thomas the Tank Engine made in Wisconsin is not the same as one manufactured in China: the paint on the Chinese twin may contain dangerous levels of lead. Also a plump red tomato from Florida is often not the same as one grown in Mexico. The imported fruits and vegetables found in our shopping carts in winter & early spring are grown with types & amounts of pesticides that would often be illegal in the United States.

In this case, the victims are North American songbirds. Bobolinks were once a common sight in the Eastern United States. In mating season, the male in his handsome tuxedo-like suit sings deliriously as he whirrs madly over the hayfields. Bobolink numbers have plummeted almost 50 percent in the last four decades, according to the North American Breeding Bird Survey.

The birds are being poisoned on their wintering grounds by highly toxic pesticides. Rosalind Renfrew, a biologist at the Vermont Center for Ecostudies, captured bobolinks feeding in rice fields in Bolivia and took samples of their blood to test for pesticide exposure. She found that about half of the birds had drastically reduced levels of cholinesterase, an enzyme that affects brain and nerve cells — a sign of exposure to toxic chemicals.

Since the 1980s, pesticide use has increased fivefold in Latin America as countries have expanded their production of nontraditional crops to fuel the demand for fresh produce during winter in North America and Europe.
Rice farmers in the region use monocrotophos, methamidophos and carbofuran, all agricultural chemicals that are rated Class I toxins by the World Health Organization, are highly toxic to birds, and are either restricted or banned in the United States. In countries like Guatemala, Honduras and Ecuador, researchers have found that farmers spray their crops heavily and repeatedly with a chemical cocktail of dangerous pesticides.

In the mid-1990s, American biologists used satellite tracking to follow Swainson’s hawks to their wintering grounds in Argentina, where thousands of them were found dead from monocrotophos poisoning. Migratory songbirds like bobolinks, barn swallows and Eastern kingbirds are suffering mysterious population declines, and pesticides may well be to blame.
A single application of a highly toxic pesticide to a field can kill seven to 25 songbirds per acre. About half the birds that researchers capture after such spraying are found to suffer from severely depressed neurological function.

Migratory birds, modern-day canaries in the coal mine, reveal an environmental problem hidden to consumers. Testing by the United States Food and Drug Administration shows that fruits and vegetables imported from Latin America are three times as likely to violate Environmental Protection Agency standards for pesticide residues as the same foods grown in the United States. Some but not all pesticide residues can be removed by washing or peeling produce, but tests by the Centers for Disease Control show that most Americans carry traces of pesticides in their blood. American consumers can discourage this poisoning by avoiding foods that are bad for the environment, bad for farmers in Latin America and, in the worst cases, bad for their own families.

Most mass-produced coffee is grown in open fields heavily treated with fertilizers, herbicides, fungicides and insecticides. In contrast, traditional small coffee farmers grow their beans under a canopy of tropical trees, which provide shade and essential nitrogen, and fertilize their soil naturally with leaf litter. Their organic, fair-trade coffee is now available in many coffee shops and supermarkets, and it is recommended by the Audubon Society, the American Bird Conservancy and the Smithsonian Migratory Bird Center.
Bananas are typically grown with one of the highest pesticide loads of any tropical crop. Although bananas present little risk of pesticide ingestion to the consumer, the environment where they are grown is heavily contaminated.
When it comes to nontraditional Latin American crops like melons, green beans, tomatoes, bell peppers and strawberries, it can be difficult to find any that are organically grown. We should buy these foods only if they are not imported from Latin America.

Now that spring is here, we take it for granted that birdsong will fill the air when our apple trees blossom. But each year, as we continue to demand out-of-season fruits and vegetables, we ensure that fewer and fewer songbirds will return.


Bridget Stutchbury, a professor of biology at York University in Toronto, is the author of “Silence of the Songbirds”