The mystery behind poisoned ravens in Iqaluit deepened this week with the discovery by local wildlife officers of two more dead birds.

Seven other carcasses of the protected birds have been discovered around the Nunavut capital since January. Analysis of three of the ravens at University of Guelph showed two had tested positive for Avitrol, a poison commonly used in the agricultural industry to control pest birds.

Douglas Campbell, a pathiobiologist with the university, said Wednesday he was surprised to find Avitrol in the dead ravens.

"[It] makes you wonder exactly who is using it and where they are getting it from," he said.

Campbell said Avitrol is not meant to kill birds, but it is used to make them act abnormally to deter other birds from landing in the same area. It is usually mixed with feed such as corn, he added.

Wildlife officials, who have been investigating the deaths since January, have asked for the public's help in identifying who may have brought the chemical up north and used it on the ravens.

Under the Nunavut Wildlife Act, it is illegal to poison or kill ravens. Individuals who violate the act can face fines of up to $500,000, while corporate violators can face fines as high as $1 million.

The two new raven carcasses will be sent for analysis next week to determine the cause of death.

In 2005, McGill University scientist Dr. Louis Lefebvre, who invented a method of measuring birds' IQ, called the the corvidae, which includes ravens, the most intelligent birds in the world.