Two Calgary Zoo employees have been disciplined after a great grey owl was killed on Sept. 26, 2012, due to human error.

The owl was being transferred from one holding area to another when it flew into a connecting gate and was fatally injured.

"Our zoo management team felt that the keepers had not taken the reasonable precautions expected of all staff to ensure the safety of the owl," said Laurie Skene, manager of communications.

Skene says a subsequent investigation found the two keepers did not follow all the necessary protocols, including not planning out the transfer and not using radios to communicate with each other.

The zoo is not providing details on what disciplinary action was taken against the employees.

Laurie Skene says the two keepers have taken responsibility for their actions and are still working at the Calgary Zoo.