It’s a federal law.
From Wikipedia: “In 1973, President Richard Nixon declared current species conservation efforts to be inadequate and called on the 93rd United States Congress to pass comprehensive endangered species legislation.[1] Congress responded by creating the Endangered Species Act of 1973 which was signed by Nixon on December 28, 1973 (Pub.L. 93-205).”
Good old Tricky Dick. He was NOT a conservative, despite the drubbing the leftists gave him.
The ESA does not spell out a specific number of breeding pairs of Grey Wolves in Wyoming.