Study: Wyoming mule deer numbers suffer from energy development
CASPER, Wyo. — Mule deer in southwest Wyoming have not adapted to oil and gas wells on their winter range, according to a 17-year study that also documented a 36 percent decline in deer populations exposed to energy development.
“The study shows the trade-offs of energy development in critical wildlife habitat,” said researcher Hall Sawyer, who has studied deer in southwest Wyoming since the 1990s.
The study looked at the Pinedale Anticline in Sublette County, where mule deer spend the winter and where one of the largest gas fields in the country encroaches on their winter range.
The study, published online by the journal Global Change Biology, began in 1998, two years before intensive drilling began in 2000-01.
“Twenty years ago we didn’t really have a good idea of what was going to happen, if deer would avoid these areas or it would change anything or not,” said Sawyer, the lead author of the article. “As development progressed, it became clear quickly that deer avoided well pads. It also became clear that mule deer numbers began to drop off.”
Sawyer said the deer perceive wells and other oil and gas infrastructure as risky and try to keep their distance. As a result, their habitat is reduced, resulting in fewer animals.
The paper doesn’t make any recommendations but simply presents data from almost 200 mule deer that were monitored with the use of special collars placed on them, Sawyer told the Casper Star-Tribune.
A representative from the Petroleum Association of Wyoming didn’t immediately return a message for comment.
About 5,200 mule deer wintered on the Pinedale Anticline when 700 producing well pads were approved by the Bureau of Land Management in the summer of 2000. BLM approved another 4,400 wells in 2008.
The work was not conducted without concern for wildlife. Companies spent millions of dollars on horizontal wells, pipes to transfer liquids instead of trucking them, and modified fences.
The BLM also required that most wells couldn’t operate during the winter in designated winter ranges.
Even with remediation efforts and a 45 percent decrease in hunting mandated by the Wyoming Game and Fish Department, the deer herd dropped overall by 16 percent since 2001 and the deer wintering on the Anticline declined by 36 percent, the paper states.
Sawyer said the study showed that the mitigation efforts can reduce but not eliminate the effects of energy development.
“When we lose critical habitat and when we lose extra acres of habitat because of avoidance, we should expect fewer animals,” he said.