Hangry
It did not improve their 'hatch-rate'.
The chemical is likely DDT, a pesticide used in the past. DDT accumulated in the tissues of organisms, resulting in fragile eggshells when carnivorous birds like eagles or hawks consumed contaminated food. This eventually led to population declines in these bird species due to reproductive issues.
Elimination of the use of DDT as a pesticide.
from the bug killers DDT
DDT entered the food chain because it was in the water of the fish that bald eagles ate.
A combination of being hunted as vermin to protect farmer's chickens, etc. (from late 1700s until recently) and the effects of DDT on their eggs which reduced the number of hatchlings dramatically (from 1950s until DDT was banned in most countries).
The bald eagle was endangered because of the use of DDT it weakened the shell of the eagles and they would break so the babies could not develop. DDT almost destroyed the bald eagle. Now since DDT has been banned the Bald eagle has made a great comeback.
DDT was a pesticide that was used to kill bugs on farms. But when pretadors of those bugs were eaten by other predators the level of DDT rose and made the Bald Eagles egg shells very thin and usually the bald eagle would die. DDT is now outlawed, but the levels of DDT are still in fish and insects.
from things like ddt, humans cutting down trees and pollution
DDT can make egg shells so thin that birds can't hatch their young.
DDT caused eggshells to be too brittle to hatch, and the eagles numbers plummeted..With the banning of DDT the population has rebounded to a point where they are no longer endangered.
DDT is dangerous for all living beings; but also is a very good insecticide.