Phage
DDT (at "normal" levels) does not kill birds. It supposedly weakens the shells of the their eggs, causing them to break before
hatching.
Just to add a little both is true. DDT is highly persistent in the environment. So if you spray the ground where the birds eat worms, the bird will
suffer the equivalent of absorbing the same amount of DDT as though the bird had eaten it directly.
Basically, if you reduced the DDT to the absolute MINIMUM, and I mean ABSOLUTE MINIMUM amount required to be effective at all, small birds will die,
larger birds would consume enough to where any eggs they had would have eggshells so thin that they would collapse under the weight of the embryo thus
preventing all breeding of birds. Practically all common birds die with absorption of 20-30 parts per million of DDT...i.e. incredibly little.
This is why environmental persistence is evaluated when they try and bring pesticides on the market. Some types can take decades to be dilluted by the
ecosystem. Due to the persistence of DDT some of the food chains of countries that did not ban DDT have been nearly wiped out. DDT is not actually
illegal worldwide and still used in some parts of the world, I had a friend who went to India on a missions trip and said it freaked him out going
through a forest with no noise, no animals, only plant life.
The reputation of DDT has softened some in the last couple decades as the PR firms that were hired by the tobacco companies to say cigarette smoke
does not cause cancer were also hired by the same DDT manufacturers. Sometimes you may hear statements regarding Malaria and the third world needing
DDT but their are more effective and CHEAPER alternatives available, it is pure disinformation.
Of course the rodents of the sky...the pigeon, I don't feel so bad about DDTing them...especially after washing the car.