More misunderstanding of the case against DDT

Well-meaning but misinformed dog breeder Terrierman (a guy who goes by the handle PBurns, too)  is just the latest to fall victim to false and nearly false claims about DDT and its effects on birds.

One of the claims made by pro-DDT and anti-environmental protection, anti-science groups is that DDT is not the bad guy in bird deaths.  The late DDT-nut Gordon Edwards said DDT had nothing to do with eagle deaths, and pointed to the 300-year decline in eagle populations from the time European settlers began shooting at them.  This idea has been touted by the chief junk science purveyor, Steven Milloy, and by many others over the years.

So, in one of his several posts slamming eagle conservation efforts that include stopping the use of DDT, Terrierman said:

What’s the story? Simple: that Bald Eagles and Osprey were pushed to the edge of extinction by DDT.

Not True.

Actually, that is true.  Terrierman got it wrong.  DDT was, indeed, threatening the very existence of the bald eagle.  While it is true that there were other pressures, some long-standing, it is also true that once those problems were cleared, DDT still barred the recovery of the eagle, plus other species like osprey, peregrine falcons, and brown pelicans.

What is the story?  The story is that eagles have been under assault since Europeans found America.  By 1900, eagle populations across North America were dramatically and drastically reduced.  A federal law in 1918 made it illegal to shoot eagles, but it had little effect.  A tougher law passed in 1940 finally got some traction.

But eagle recovery didn’t take off.  In the late 1940s and early 1950s bird watchers, and bird counters like those volunteers who contribute to the annual Audubon Christmas Bird Count, noticed that young eagles disappeared.  Simply, adult, breeding eagles were not able to produce young who survived to migrate, mature, and breed later.

The culprit was DDT.  DDT kills young eagles in three ways, known in the 1960s.  It poisons them so they cannot grow in the egg.  It poisons them so they die after a period of growth.  It poisons them so they are unable to eat and digest properly, so they die shortly after they hatch.

DDT can also screw up the sexual organs of young birds, so they are unable to breed — perhaps a fourth way DDT kills young, by simply preventing their creation.

Then, in the 1970s, we found another way DDT kills species:  DDT makes the eagle hens unable to form competent eggshells.  The young die because the eggs cannot survive incubation.

DDT also kills adult eagles, especially migrating birds.  DDT accumulates in fat tissues, those fats that migrating birds burn.  When the birds migrate, the DDT comes out, and it can literally stop the heart or brain of the bird in flight.  (It kills bats the same way.)  Birds lost in migration rarely get found for necropsy.   The bird count simply falls, the population sinks one individual closer to extinction.

Does the dog breeder know all of this?  I can’t tell — I tried to correct his errors at his blog site, but after I provided a link to an article that showed DDT appears to be harming California condors as well — in a post he has censored in moderation and which will never see the light of day at Terrierman, I predict — it’s clear he’s not up to gentle correction.

One more blog from which I am banned from telling the facts.

PBurns, if you’re bold enough to comment here, your comments won’t be censored (so long as not profane).  We need robust discussion, and I encourage it.

Below the fold — my final post to Terrierman, which he won’t allow through moderation.

My post:

http://www.blogger.com/comment.g?blogID=7684843&postID=8648228318805749606&page=1&token=1324453058722&isPopup=true

I see you don’t know how to use Google, PBurns . . .

Or, perhaps, we can leave off the insults that we know are inaccurate, and discuss the issues.

California Condors and DDT:

The article tells the story:

<i>Joe Burnett, a senior wildlife biologist with the Ventana Wildlife Society and the lead biologist for the Central California condor recovery program, who had been monitoring the condor pair, was delighted with this promising development in the continuing effort to save the nation’s largest bird from extinction. When this first breeding attempt proved unsuccessful, Mr. Burnett attributed it to the young birds’ inexperience. But when he climbed the giant tree to examine the abandoned nest, he was stunned at what he uncovered: the first evidence of a potentially significant new hurdle for the condor program.

“The eggshell fragments we found appeared abnormally thin,” Mr. Burnett said. “They were so thin that we had to run tests to confirm that it was a condor egg.” The fragments reminded him of the thin-shelled eggs from birds like brown pelicans and peregrine falcons, which had been devastated by DDT but are now on the rebound.

The discovery raised a disturbing question: could DDT — the deadly pesticide that has been banned in the United States since 1972 — produce condor reproductive problems nearly four decades later? </i>

I don’t know if the stuff is even published in journals, yet.  I was alerted to it by workers in the condor program several weeks before the story in the NY Times.

The Times story continues — first one up on Google:

<i>Once Montrose stopped discharging DDT into the sewer, that contamination source disappeared. “Brown pelicans rebounded fairly quickly after the dumping stopped,” Dr. Witting said.

James Haas, the environmental contaminants program coordinator for the Pacific Southwest region of the United States Fish and Wildlife Service, noted that other birds in the region that feed higher on the food chain, like bald eagles, continue to suffer from DDT-induced eggshell thinning.

Concerns about condors and DDT have prompted the Fish and Wildlife Service to initiate a new one-year project to study how marine mammals might be carrying Montrose DDT up the California coast. The main investigator, Myra Finkelstein at the University of California, Santa Cruz, is also leading a four-year study to investigate risk factors and management strategies to ensure the condor’s long-term sustainability. This includes not only DDT but also poisoning that comes from ingesting lead-bullet fragments found in hunter-shot game. Lead poisoning was a major factor in the bird’s brush with extinction and remains the primary danger today to released condors.

Because of the lead poisoning problem, in 2008 California enacted legislation requiring hunters in condor country to use ammunition without lead.

Despite lead poisoning and the emerging DDT challenge, Mr. Burnett remains optimistic. He is hopeful that taking steps like capping the DDT-contaminated Montrose marine sediments as well as continuing research will provide solutions. He notes that in 1982 the population of California condors had been reduced to 22 birds. Although problems remain, bringing back the condor has been a conservation success story. There are now 380 California condors in the world, with about half of these titans of the sky flying free in the Western United States. </i>

Got citations on eagles not being threatened by DDT?  I haven’t found any on Google.