The shell of this pelican egg is unusually thin, and has already developed hairline cracks. Why are thin eggshells a hazard for pelicans and other birds?
The powerful insecticide DDT (now outlawed in the U.S.) was linked to thinning eggshells in pelicans in the 1960s, when this photograph was taken. Most other birds affected by DDT were raptors. What are raptors?
Pelicans and raptors are near the top of their food chains. Why do you think they suffered more dramatic effects from DDT (such as thinning eggshells) than lower-level predators such as chickens and quail?
Term Part of Speech Definition Encyclopedic Entry biomagnification Noun
process in which the concentration of a substance increases as it passes up the food chain.
measure of the amount of a substance or grouping in a specific place.
(dichloro-diphenyl-trichloroethane) toxic chemical used as an insecticide but illegal for most uses in the U.S. since 1972.
food chain Noun
group of organisms linked in order of the food they eat, from producers to consumers, and from prey, predators, scavengers, and decomposers.
Encyclopedic Entry: food chain hazard Noun
danger or risk.
protected area built by birds to hatch their eggs and raise their young.
natural or manufactured substance used to kill organisms that threaten agriculture or are undesirable. Pesticides can be fungicides (which kill harmful fungi), insecticides (which kill harmful insects), herbicides (which kill harmful plants), or rodenticides (which kill harmful rodents.)
animal that hunts other animals for food.
primary consumer Noun
organism that eats plants or other autotrophs.
bird of prey, or carnivorous bird.
secondary consumer Noun
organism that eats meat.
tertiary consumer Noun
carnivore that mostly eats other carnivores.