Cause of death revealed for 3 great horned owls found dead in Lincoln Park

CHICAGO - The official cause of death has been revealed for the three great horned owls found dead in Lincoln Park earlier this year. 

All three owls — an adult male, an adult female and a baby — died from rodenticide toxicosis, which is poisoning caused by rat poison.

The head veterinarian at the Community Engagement-DuPage Wildlife Conservation Center said that multiple anticoagulant rodenticides were found in their systems. The male owl was discovered in mid-April, the owlet in March and the female in May.

Annette Prince, director of Chicago Bird Collision Monitors (CBCM), shared that the great horned owl family was a cherished part of the community.

"They were a wonderful family. They gave everyone a beautiful show of how they were raising their baby, but unfortunately, the food that they fed that baby possibly came from rodents that had eaten toxic rodenticide," Prince said.

Prince said when animals ingest rat poison, it can cause uncontrollable internal bleeding and lead to death.

In some cases, animals are poisoned directly by consuming pellets or other bait. Experts said in this case, it is more likely the great horned owl family unknowingly hunted prey that had previously ingested rat poison.

"It’s a secondary poisoning by eating a prey item. And that happens to any wildlife, like a coyote or fox, anything else that might feed on a rat or a mouse," said Prince.