The first golden eagle in Yellowstone to be fitted with a tracking device has reportedly died of lead poisoning.
ABC News reports officials with the U.S. Geological Survey confirmed the death of the eagle and attributed the lead poisoning to the bird likely consuming lead bullet fragments while scavenging for food in the fall and winter months.
"It's a little gut-wrenching because it's so darn hard to trap and tag an eagle, and it's frustrating for the graduate student who's leading the project," eagle scientist Todd Katzner with the U.S. Geological Survey said, according to ABC News.
The female eagle was equipped with a backpack-like radio transmitter that tracked its whereabouts at all times, with it recently flying outside the national park boundary.
It likely ate the remains of an animal killed by hunters outside the park.
Since the bird was first equipped with the tracking unit, several others eagles have followed suit, maintaining research efforts for the animal.
Advocacy groups have called for hunters to use copper in bullets instead of lead, arguing such a practice could prevent these types of deaths in animals.
The eagle was found dead in December in the northern portion of the massive national park but its cause of death was just recently concluded.
The golden eagle is the most widely populated species of eagle, considered to have a stable population.