The mystery of the declining elk herd

Something is killing a growing number of young elk calves in our forests. Division of Parks and Wildlife biologists are scratching their heads, trying to figure out “what and why.”

There are no “usual suspects” to round up in this mystery. No disease, no large number of poachers, no excess of predators, and no clear reason for juvenile elk to die young.  

Researchers have told the Durango Herald that about fifty percent of the elk calves born in Southwestern Colorado are dying before they are six months old. Among those who live that long, an additional 15 percent die before they are a year old. 

Each winter, Division of Parks and Wildlife choppers fly over elk herds checking over the animals. The main thing they watch out for is the ratio of elk cows to calves. If there are quite a few calves, the herd is generally in good shape. The herd population would be stable, and the number of elk should grow. But, if the calves are dying young, you can expect the entire herd to struggle to survive. 

To keep the herds in perspective, 15 years ago there were about 50 to 60 calves among 100 elk cows, on average; biologists figured this was a decent percentage per herd. But now, the number has fallen about just 20 calves per one hundreds cows. 

 That number is right at the core of the mystery. 

You might think that there might be some kind of pregnancy problem in the southwestern herds. Well, senior terrestrial biologists Scott Wait, of the Colorado Parks and Wildlife Division, told the newspaper that the animals are having no problem getting pregnant; in fact, 90 percent of the cows in the southwest are generally giving birth to healthy calves. 

Herds in northwestern Colorado are subject to the same predators and the same diseases as their southwestern cousins, but are not suffering from calves dying in enormous numbers. 

A second year of research on the problem is based in Montrose and Trinidad, and they are finding similar difficulty among the elk. So they are placing radio collars on the elk calves to track the animals. Wait told the Durango Herald “We are seeing significant mortality during those first six months,” of life.  

While the scientists are looking for clues, some hunters think the problem might have to do with the rutting season. 

Every mid-August, elk socialize in large numbers in the San Juan Mountains. This is called the rut, when bulls fight with each other over cows, and the winners get to mate, with a lot of elk calls echoing through the forests.  

There are also quite a few humans prowling the San Juan Mountains at that time, as hunters from around the country come in search of big game.  

After the rut begins, elk usually breed during between the last week of September and the first week of October. This means calves will be born late May and early June. Nature will then grow bulk and muscle before winter sets in, thus giving the calves a fighting chance to survive the cold. 

If the rut is disrupted by people moving around in the San Juan Mountains, some experienced hunters think this could result in late-born calves. That, in turn, could mean young calves that don’t get a chance to bulk up for winter—and calves that die in the cold. 

Hopefully, wildlife biologists, ethical hunters, and the Colorado Parks and Wildlife Division will join forces to save these magnificent animals. 



About the author

Dave Segal

Dave Segal

Dave Segal, a Detroit native, has been a journalist since 1977. He has worked as a reporter, commentator, and news director at radio stations in Detroit, Denver, and Montrose.

Dave has been writing and editing for the Monitor since its first print issue in 2003. He is editor and senior writer for the digital magazine. On the side, Dave has also done freelance writing, media relations, and a variety of volunteer work.