A central Illinois zoo is mourning the loss of one of its own.

Spencer, one of Miller Park Zoo's North American River Otter, has passed away.

Zoo officials say the death was not related to COVID-19.

An autopsy will be performed on Spencer at the University of Illinois Veterinary College.

“We are saddened by the loss as Spencer was a favorite of staff and guests. Cause of death has not yet been determined. A mass was found in the abdomen and tissue has been sent off for diagnosis” said Miller Park Zoo Interim Director Anthony Nelson.