PORTLAND -- The Oregon Zoo says its last gray wolf had to be euthanized today because his declining health made it tough for him to get around.

Gray wolves typically live in the wild for six to eight years, but Marcus made it all the way to 13.

 Also: Geriatric wolf euthanized at Oregon Zoo

Last April, veterinarians euthanized Marcus' mate, Ceann following surgery to remove a tumor from her shoulder. Her death left Marcus as the last member of the pack.

Ceann and Marcus were born in April 1995 in Battle Ground, Ind. They arrived at the Oregon Zoo two months later, in June 1995.