(Reuters) - The deaths of 13 bald eagles in Maryland's largest die-off of the U.S. national bird in three decades were caused by humans, officials said on Thursday.
Lab results showed that the eagles did not die of natural causes, including diseases such as avian influenza, said U.S. Fish and Wildlife Service spokeswoman Catherine Hibbard. The agency declined to say whether the birds were poisoned.
"Our investigation is now focused on human causes and bringing to justice the person(s) responsible for the death of these eagles," Hibbard said in a statement.
Maryland Natural Resources police received a call on Feb. 20 reporting four dead eagles near Federalsburg in the eastern part of the state. Officers arrived and discovered nine more dead birds nearby.
The 13 birds represented Maryland's largest bald eagle die-off in 30 years, officials said.
The bald eagle, which almost disappeared from the United States decades ago, was removed from the federal endangered species list in 2007 after habitat protection and the banning of the pesticide DDT led to its recovery.
The federally protected bird is a symbol of the U.S. government and is featured on currency and in the presidential seal.
The maximum fine for harming a bald eagle is $100,000 and up to one year in prison, Hibbard said.
(Reporting by John Clarke in Washington; Editing by Lisa Von Ahn)