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Ocean Watch
By Susan Scott
Monday, March 27, 2000
A couple of years ago, a biologist I know was visiting a state office on Punchbowl Street. Pesticide should not
be sprayed till
birds migrateWhen he came out, he witnessed an appalling event: Workers dressed in protective chemical suits and wearing respirators were spraying lawns occupied by several plovers.
When the workers were finished, they flagged the area with signs that said: "Toxic Chemicals. Stay Off."
This occurred just three to four days before the birds' spring migration. "It's only common sense to defer spraying until the birds are gone," the biologist wrote me.
He's right, of course. A nd now, a study confirms that delayed spraying is more than common sense -- it should be mandatory.
Deborah Rudis, a U.S. Fish and Wildlife biologist, presented the study at the recent Alaska Bird Conference in Sitka. Rudis found that Sitka ravens died after application of the common lawn pesticide Diazinon, despite the fact that the chemical was used according to directions.
Diazinon is an insecticide first registered for use in the United States in 1952.
It is used to control insect pests in a wide variety of situations: field crops, fruits, nuts, vegetables, ornamentals, forestry, livestock, residences and commercial sites.
In Hawaii, people commonly use products containing Diazinon on private lawns and in outdoor gardens to kill insect pests.
BUT this stuff kills other animals, too. In 1975, 14 Canada geese were found dead on a golf course in Missouri. Researchers discovered Diazinon on grass taken from one goose's mouth, and the rest showed signs of Diazinon poisoning. The most recent Diazinon application to the golf course had been three months earlier.
Evidently, this so-called "short-lived" chemical can kill birds months after treatment.
Normally, in ideal conditions Diazinon degrades rapidly, with a half-time persistence of about 14 days. This means that in two weeks, half the chemical applied to the lawn is gone. In another two weeks, half of the remainder is gone. And so on, until the amount is near zero.
The weather, however, does not always cooperate in getting rid of Diazinon. If rain is scarce and the lawn is not watered well, Diazinon can remain active for up to six months.
Since plovers eat insects in grass for nearly eight months of the year here, the dead-raven study from Sitka is bad news for Hawaii's shorebirds. It is also an update of old news.
In a 1986 U.S. Fish and Wildlife report, 54 Diazinon poisoning incidents were described in 17 states among 23 species of birds. These waterfowl and songbirds died after eating grass or seeds shortly after Diazinon application.
BIRDS such as our plovers can be poisoned by absorbing it through their skin and feet or by eating struggling, poisoned insects. And even if a plover does survive a dose of Diazinon, the chemical might have unseen effects, such as weakened ability to migrate, reduced egg production and malformed chicks.
You can help Hawaii's plovers by finding out what nonchemical options there are for controlling the type you have and using Diazinon only as a last resort.
Hawaii's golden plovers leave here in April. When pesticide application to your lawn seems the only answer, do it in May or June, just after the birds leave, then water it often. Hopefully, the chemical will degrade before your plover returns in August.
The gardeners of our public lawns should do the same.
It's only common sense.
Marine science writer Susan Scott's Ocean Watch column
appears Mondays in the Star-Bulletin. Contact her at honu@aloha.net.
