HANNA CITY, Ill. (WMBD) — Wildlife Prairie Park announced on Facebook Friday that their bison named Big Mike died of kidney failure and old age Thursday night. Big Mike was estimated to be around 15 years old.

Big Mike has been at Wildlife Prairie Park for eight years. He lived in a pen with Elsa the Elk at the park rather than with the bison herd because he was smaller and more domesticated than the rest of the herd, said staff.

“Big Mike was loved by all,” wrote Wildlife Prairie Park staff on Facebook. “Even in his early days, he was genial and loved attention. For such a large animal, he displayed humbleness, curiosity, and gentleness–all life characteristics we needed to be reminded of daily. Everyone who visited Big Mike walked away with a feeling of peace.”

Over the past few weeks, staff members reported seeing Big Mike lose interest in food, visitors, and beginning to move slowly and lose weight. Blood samples show that Big Mike was suffering from old age-related kidney failure, and he collapsed Thursday night.

Wildlife Prairie Park has set up the Big Mike Memorial Fund, which supports the park’s bison husbandry efforts. Donations can be made on their website.