Nearly Half of US Bald Eagles Suffer Lead Poisoning
2022-02-28
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1A new study found that nearly half of bald eagles tested across the United States show signs of repeated lead exposure.
2Scientists found harmful levels of lead in the bones of 46 percent of bald eagles in 38 states, from California to Florida.
3The scientists recently reported their findings in the publication Science.
4Researchers examined the blood, bones, feathers and liver tissue of 1,210 eagles between 2010 and 2018.
5Todd Katzner is a wildlife biologist at the U.S. Geological Survey in Boise, Idaho.
6He is also a co-writer of the study.
7He said, "This is the first time for any wildlife species that we've been able to evaluate lead exposure and population level consequences at a continental scale."
8He said it was "stunning," or very surprising, that nearly 50 percent of the birds showed signs of lead exposure.
9Lead is a poisonous substance that affects the nervous system and interferes with the normal function of nerve cells.
10Even in low amounts, lead can reduce bald eagles' ability to fly, hunt and reproduce.
11In high amounts, lead causes seizures, breathing difficulty and death.
12Similar rates of lead exposure were found in golden eagles.
13Scientists say that means the birds likely ate animal meat containing lead from ammunition or fishing equipment.
14The study estimated that lead exposure reduced the yearly population growth of bald eagles by 4 percent and golden eagles by 1 percent.
15Bald eagles are one of America's most celebrated conservation success stories.
16The birds were removed from the U.S. Endangered Species List in 2007.
17But scientists say that high lead levels are still a concern.
18Lead exposure also reduces their ability to face future difficulties, such as climate change or infectious diseases.
19"When we talk about recovery, it's not really the end of the story - there are still threats to bald eagles," said Krysten Schuler.
20She is a wildlife disease ecologist at Cornell University's College of Veterinary Medicine and was not involved in the study.
21Earlier studies have shown high lead exposure in some areas of the U.S., but not across the country.
22The blood samples from live eagles in the new study were taken from birds trapped and studied for other reasons.
23The bone, feather and liver samples came from eagles killed by vehicles, power lines or other causes.
24"Lead is...available to these birds more than we previously thought," said co-writer Vince Slabe.
25He is a research wildlife biologist at the nonprofit group Conservation Science Global.
26He added that a small piece of lead "the size of the end of a pin" is large enough to cause death in an eagle.
27The researchers also found higher levels of lead exposure in fall and winter.
28During these months, eagles eat animal remains left by hunters.
29These remains often contain many pieces of lead ammunition.
30Slabe said he hopes the findings provide a chance to "talk to hunters about this issue in a clear manner."
31He added that he hopes more hunters will voluntarily begin using non-lead ammunition such as copper bullets.
32I'm Jonathan Evans.
1A new study found that nearly half of bald eagles tested across the United States show signs of repeated lead exposure. 2Scientists found harmful levels of lead in the bones of 46 percent of bald eagles in 38 states, from California to Florida. The scientists recently reported their findings in the publication Science. 3Researchers examined the blood, bones, feathers and liver tissue of 1,210 eagles between 2010 and 2018. 4Todd Katzner is a wildlife biologist at the U.S. Geological Survey in Boise, Idaho. He is also a co-writer of the study. He said, "This is the first time for any wildlife species that we've been able to evaluate lead exposure and population level consequences at a continental scale." He said it was "stunning," or very surprising, that nearly 50 percent of the birds showed signs of lead exposure. 5Lead is a poisonous substance that affects the nervous system and interferes with the normal function of nerve cells. Even in low amounts, lead can reduce bald eagles' ability to fly, hunt and reproduce. In high amounts, lead causes seizures, breathing difficulty and death. 6Similar rates of lead exposure were found in golden eagles. Scientists say that means the birds likely ate animal meat containing lead from ammunition or fishing equipment. 7The study estimated that lead exposure reduced the yearly population growth of bald eagles by 4 percent and golden eagles by 1 percent. 8Bald eagles are one of America's most celebrated conservation success stories. The birds were removed from the U.S. Endangered Species List in 2007. But scientists say that high lead levels are still a concern. Lead exposure also reduces their ability to face future difficulties, such as climate change or infectious diseases. 9"When we talk about recovery, it's not really the end of the story - there are still threats to bald eagles," said Krysten Schuler. She is a wildlife disease ecologist at Cornell University's College of Veterinary Medicine and was not involved in the study. 10Earlier studies have shown high lead exposure in some areas of the U.S., but not across the country. 11The blood samples from live eagles in the new study were taken from birds trapped and studied for other reasons. The bone, feather and liver samples came from eagles killed by vehicles, power lines or other causes. 12"Lead is...available to these birds more than we previously thought," said co-writer Vince Slabe. He is a research wildlife biologist at the nonprofit group Conservation Science Global. He added that a small piece of lead "the size of the end of a pin" is large enough to cause death in an eagle. 13The researchers also found higher levels of lead exposure in fall and winter. 14During these months, eagles eat animal remains left by hunters. These remains often contain many pieces of lead ammunition. 15Slabe said he hopes the findings provide a chance to "talk to hunters about this issue in a clear manner." He added that he hopes more hunters will voluntarily begin using non-lead ammunition such as copper bullets. 16I'm Jonathan Evans. 17Christina Larson reported on this story for the Associated Press. Jonathan Evans adapted this story for Learning English. 18________________________________________________________________ 19Words in This Story 20exposure - n. the fact or condition of being subject to some effect or influence 21evaluate - v. to judge the value or condition of 22consequences - n. things produced by a cause or following from a condition 23seizures - n. an abnormal state in which a person usually experiences convulsions and may become unconscious