Scientists in Colorado say they hope they can cut the size of the bison herd at a former federal arsenal in the Denver area without killing any of the animals. There are 85 bison at the Rocky Mountain Arsenal Wildlife Refuge in Commerce City, peacefully grazing with Denver office towers in the background, The Denver Post reported Friday. The herd lures about 300,000 visitors a year. Biologists say there are too many of the animals for the available land to support. They want to reduce the herd to 60 and keep it at that level until more prairie can be added to the refuge. Experts are looking for new homes for bison that will be rounded up Dec. 17 and hope space can be found in other refuges. Part of the problem is that vestiges of the wild west, like the Denver refuge, attract tourists and that attracts developers. There are plans for hotels, shopping and other building near the refuge, development Denver Mayor Michael Hancock said Friday is "inevitable." As many as 20 million bison once lived on the western plains. The federal government's Bison Conservation program is intended to stabilize the national herd at about 10,000, living in national and state parks and other refuges. "There are very few places in the United States where bison will be free-roaming," said Dave Lucas, a biologist who manages the Denver refuge. "We have roads, yards, fences and people. Our country is not that wild anymore."