ARLINGTON, Mass. (WWLP) — A well-documented bald eagle in eastern Massachusetts was in critical condition Monday after it was believed to have ingested rat poison.

The female bald eagle, known as MK, was found on the ground in an Arlington cemetery, weak and unable to fly away after what exam results later suggested was anticoagulant rodenticide poisoning, the New England Wildlife Center said in a Facebook post.

The center said such poisoning happens when a raptor eats a rodent that has ingested poison itself.

The center, which described MK as “unable to get significant lift off the ground after many attempts to fly away,” said the bird was taken to its Cape Cod hospital.

The center said the eagle was “severely anemic, lethargic, and [barely] able to stand” on her own, though she had not suffered any broken bones. It also said her blood was clotting slower than normal.

The center’s veterinary team has been administering fluids, pain medications, oxygen and treatments to improve blood clotting.

“Our veterinary team will be by her side and monitoring her closely as we try to get her through this,” the center said on Facebook.

MK, which was not carrying any eggs, was herself hatched in Waltham in 2016 and is the mate of a bald eagle named KZ. MK and KZ frequently visit the Mystic River watershed.

“This pair is considered a true ecological success story here in Massachusetts and a testament to how far the Mystic River and its habitats have come over the past few decades,” the center said on Facebook, referring to the decline of the watershed due to urban development and pollution. “They even had a children’s book written about them!”