If so, this would be the first confirmed wolf killed in Colorado since 2009. One was hit by a vehicle that year. Another was poisoned.
U.S. Fish and Wildlife Service officials said a DNA analysis hasn't been completed.
The hunter, who has not been identified, thought the animal he shot April 29 was a coyote, Colorado Parks and Wildlife spokesman Matt Robbins said.
"He did everything right" in swiftly reporting the killing on federal land near Wolford Mountain Reservoir to CPW officials at Hot Sulphur Springs, Robbins said.
But under the Endangered Species Act, a hunter can be prosecuted for killing a protected species without a permit.
The Obama administration in 2013 proposed removing gray wolves from the endangered species list. USFWS wolf recovery coordinator Mike Jimenez said wolves in the northern Rocky Mountains are stable and may be spreading.
"By all biological criteria, wolves are recovered and there are no threats to the population," Jimenez said.
Mature males leave their packs, often migrating 60 miles, Jimenez said. USFWS biologists have recorded wolves dispersing over 500 miles.
In December, a man in Utah killed a wolf known widely among schoolchildren as Echo, saying he thought he was shooting at a coyote. The feds are investigating and weighing whether to file charges.
Wildlife advocates urged aggressive enforcement. Colorado officials must protect wolves, not just tolerate them, and notify residents they may be present, said Michael Robinson of the Center for Biological Diversity.