A Wyoming researcher recently discovered that mule deer continue to avoid areas developed by oil and gas companies, after more than fifteen years.

Biologist Hall Sawyer has been studying a herd near Pinedale since 2000, just as more oil and gas wells were starting to appear on the landscape. Because the deer have steered clear of development, Sawyer says they have had a smaller winter range. The herd’s population started declining in just two years, and by now it has shrunk by 40%.

Sawyer’s data stands out because for a long time, land agencies have considered avoidance a short-term impact, assuming that species grow accustomed to development.

“What we found was just the opposite,” Sawyer said. “In fact, mule deer continued to avoid these well pads through 15 years of development, suggesting that these are long-term impacts.”

Sawyer said the study did not include this past winter, which was exceptionally hard on deer populations. Instead, it ended after several milder winters. Another takeaway, he said, is that the oil and gas companies in the area were already doing plenty to try to minimize their impact on local wildlife.

“The impacts that we saw were with mitigation in place. So I guess the story there is that mitigation can reduce impacts but not really eliminate them,” Sawyer said.

Kelly Bott of Ultra Petroleum said in a statement that her company supports mule deer research, but she called these results premature, since companies are still actively drilling in the area. Bott said they expect animals to habituate to oil and gas projects once they are in the “production-only phase”.

The question for management may still be whether it is accurate to call the impacts of the “drilling phase” a short-term state of affairs.