Cheyenne Mountain Zoo officials are searching for two green Aracari toucans that disappeared over the weekend -- and they think humans may be to blame.
The animals, one male and one female were discovered missing on Saturday.
The toucans have lived at the zoo for five years and never tried to escape.
To leave the exhibit, they would have had to fly through at least two doors.
Zookeepers doubt the birds would have sought out the cooler air outside the exhibit.
They also say it's suspicious that two birds of the same species would disappear without human help.
It is illegal to sell or trade the birds as exotic pets.
Anyone with information about the animals is asked to call the Cheyenne Mountain Zoo.