Eagles essentially went extinct
DDT has effects?
Bald Eagle Sounds (Ignore Video)
Bald Eagle Sounds
Eagle Population during 1910
The eagle population during 1910 was around 300,00-500,00
1947 DDT usage in America
Around 1947 DDT had started to be regularly used as an insecticide on farms.
1950 Decrease in Eagles
Only 412 nesting pairs were found in the 48 states of the US.
Sometimes when experts looked in the eagles nest there would be no eagle eggs.
Very few eagles were around in the 1950s.
The DDT that some eagles had eaten when they ate salmon had caused the eagles eggs to break more easily, so when they tried to warm them up or move them they would accidentally crush the eggs.
Eagles catching Salmon
Bald Eagle catches salmon
1972 Banned DDT
Believed that DDT was the reason owls were decreasing and banned them in the United States.
2000 Eagle Population
The eagle population was increasing and was now at 7200 pairs of nesting in the 2000
Silent Spring by Rachel Carson
In the book Silent Spring, Rachel Carson describes how people throughout the country observed fewer baby bald eagles in the 1950s and late 1940s compared to the 1930s and early 1940s. She describes these two specific examples in her book:“Observations at Hawk Mountain are in line with findings elsewhere. One such report comes from Elton Fawks, an official of the Natural Resources Council of Illinois. In 1958 Mr. Fawks reported that a recent count of 59 eagles had included only one immature bird. Similar indications of the dying out of the race come from the world’s only sanctuary for eagles alone, Mount Johnson Island in the Susquehanna River…Since 1934 its single eagle nest has been under observation by Professor Herbert H. Beck…Between 1935 and 1947 use of the nest was regular and uniformly successful. Since 1947, although the adults have occupied the nest and there is evidence of egg laying, no young eagles have been produced” (Carson 1962, p. 120).
DDT Time Line
DDT would run off into the lake where species would absorb it starting from Algae ---> Zooplankton ---> Small Fish ---> Large Fish ---> Fish Eating Birds.
Normal Egg vs. DDT Egg
Comparison between normal eggs and DDT Egg
The DDT egg was more easily to break than the normal eggs due to the change that the DDT had caused, making the nesting of the Eagles empty because even if they try to take care of the egg or move the egg they would accidentally crush it to pieces.