Inbreeding Didn't Cause Bighorn Sheep Populations to Decline in Colorado

First Posted: Jul 27, 2015 07:48 AM EDT

Colorado's bighorn sheep population is declining and now, scientists have found out that it's not due to inbreeding. Researchers have taken a closer look at these animals and have found that while they're isolated in their mountain ecosystems, they're not dying off due to a lack of genetic diversity.

In this latest study, the researchers used DNA testing to examine genetic diversity across five, separate herds in Rocky Mountain National Park. In particular, the scientists zeroed in on the Mummy herd, which experienced a severe population crash in the mid-1990s and has been slow to recover.

"There's been enough gene flow between the herds, primarily due to high ram migration, that the population has been genetically rescued," said Catherine Driscoll, one of the researchers, in a news release.

The researchers found that the Mummy herd, surprisingly, is maintaining healthy levels of genetic variation. However, the researchers believe it may carry higher exposure to stress factors due to its proximity to roads and trails.

Colorado's bighorn population has been declining since the 1800s. There was a sharp, 10.2 percent drop between 2001 and 2009, and wildlife managers have occasionally transplanted bighorns from other states in an attempt to restore herd numbers.

The findings reveal that when it comes to bighorn sheep populations, genetic diversity isn't to blame for the decline. Instead, it's likely environmental factors that are causing the decline. With this in mind, wildlife managers should focus on bighorn habitat rather than transplanting sheep in order to better manage numbers of animals.

The findings are published in the Journal of Wildlife Management.