Sometimes we feed poisons to birds quite indirectly. This page tells the story of how a chemical pesticide (DDT) sprayed on crops nearly drove a fish-eating bird extinct. DDT hurt the ospreys by making their eggs fragile.

This page also has two (messy) experiments to show, first, how strong the shape of an egg is, and second, how chemicals can weaken them.



Story of the Osprey

During World War II the United States government used the chemical DDT
(dichloro-diphenyl-trichloroethane) on its soldiers as a cure for insect born
diseases like malaria and typhus. After the war, DDT use as an insecticide
became popular. It was very effective against many types of pests. The
country sprayed everything from plants to animals to even people. People
did not realize that this pesticide was dangerous, everyone thought that
since it killed insects it was a good thing to be sprayed down. What
people did not realize at the time was that this chemical not only touches
living organisms on the surface but it also penetrates into the body of
the organisms.

DDT is soluble in fats and tissues and it can accumulate in the body of
living organisms. This chemical was known to cause cancer in living
animals and reduce rates of reproduction. DDT not only goes into the
bodies of living organisms but it also gets washed off into the soil and
water systems of our earth. Once the chemical enters the water systems
all the creatures that live in the water are affected by it. Just like on land
the chemical seeps into everything that it comes in contact with.

DDT would enter either through the fish’s gills or skin, and once it was
in the fish it lingered inside and made the fish carriers of it. Since fish
became one of the primary carriers of this chemical anything that ate
the fish would then become infected with the chemical as well. The
primary food source for the osprey is fish, thereby forcing the osprey
to ingest this poison.

The damage that this foreign substance did to the osprey’s body was
great. Most osprey either became sick, or even died. If the osprey were
lucky enough not to die they still suffered from the effects of the
chemical. Osprey’s eggs took the force of DDT’s damage through
drastic thinning. These thin and very brittle eggshells would squish
under the weight of the parents once they attempted to incubate them.

In 1973 DDT became banned from use in the United States. This
step towards eliminating the chemical from the environment helped
the osprey tremendously. Today through breeding programs that
build nest sites and reintroduce these birds into the wild the osprey
is making a comeback and saved itself from the endangered species list.


Conduct water testing in your school or home, in puddles outside, in
nearby streams and ponds to research the quality of water and research
the effects on wildlife.

To purchase water quality testing kits visit Carolina Biological Supply Company at


For information and lesson plans on water quality visit The Environmental Protection Agency at

For information about water quality in our oceans visit

  Hunters & Hunted
  What's for Lunch?
How's the Water
  Beaks are Tools
  Backyard Birdfeeder
  Shapes & Sizes
  Lift Off
  A Big Enough Wing
  Migration Hopscotch
  Sing Out Loud
  Virtual Incubator
  Dance of Love
  On the Egg
  Becoming a Bird
  The Big Deal: The Feather
  Dead or Alive
  Are Birds Dinosaurs?

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