Deer graze along the side of Highway 13 between Rifle and Meeker on a cold winter day. Researchers working in the Piceance Basin have found no long-term negative effects on mule deer from energy development, except for a slight decrease in fetal survival in a year also marked by severe drought.

Researchers working in the Piceance Basin have found no long-term negative effects on mule deer from energy development, except for a slight decrease in fetal survival in a year also marked by severe drought.

The findings are some of the latest to come from more than a decade of study of the impacts of energy development on deer in the Piceance Basin. The research was begun in 2008 southwest of Meeker, with data collection continuing into last year, and analysis of data results is expected to wrap up next fall or winter.

The research, led by Colorado Parks and Wildlife, has cost roughly $400,000 to $500,000 a year, and funding has come from entities including Piceance Basin energy developers, hunting groups and the federal government. It has been one of the most extensive mule deer studies ever done, said Chuck Anderson, mammals research leader for CPW. Numerous papers have been published as a result of it, not just specific to impacts from drilling but on subjects such as habitat mitigation projects and deer ecology.

The year the research started turned out to be the peak of natural gas development in the region, with activity particularly starting to drop off around 2012 in the study area. That ended up helping researchers see how deer react to drilling compared to the production phase of development. Not surprisingly, deer showed fewer signs of disturbance during lower periods of development activity.

Study results from the project released by CPW and Colorado State University several years ago, based on global-positioning-system tracking data from collared deer, found that deer on average stay a least a half a mile from active drilling sites. They strongly avoided areas closer than 600 meters to pads with active drilling during the day, and typically stayed 800 meters or more at night from the drilling rigs with their light and noise. But they were apt to come closer to pads with producing wells rather than active drilling.

Anderson said there had been an expectation that energy development has a longterm negative effect on things such as deer body condition, pregnancy rates and fawn survival. But he and other researchers are now reporting that they failed to find such impacts under most scenarios, indicating that deer can offset longterm impacts through behavioral changes that involve moving away from development activity. Overall, researchers saw a similar number of deer and similar rates of population growth in areas of energy development activity, and areas lacking it, Anderson said.

He qualified these findings by noting that the study was in an area where companies were drilling multiple wells directionally from each pad, reducing the density of pads, and deer weren’t limited by habitat and forage conditions, meaning they could move away from activity to suitable habitat.

“Under those conditions, overall there was no longterm negative effect on the deer population as a whole,” he said.

The one exception researchers found was in the drought year of 2012, when they documented a slight negative effect in areas of active drilling on fetal survival, as measured by doe pregnancy rates in March versus how many fawns were born in June. Anderson said that effect wasn’t documented during two subsequent years with better moisture, which suggests that severe drought and extensive development may act as compounding factors affecting fetal survival.

CPW recently has been recommending to agencies such as the Bureau of Land Management that energy development in critical big game habitat be limited to one pad per square mile. Anderson said the results of his recommendation would suggest the agency could relax that recommendation a bit. He said the highest pad density where the Piceance research occurred was just under one per square kilometer (a kilometer is about six-tenths of a mile).

“The deer were able to handle that,” said Anderson.

Anderson said now that researchers have a better understanding, based on the Piceance research, about how deer react to different aspects of energy development, that can provide for the creation of a planning tool to minimizes impacts.

“If the companies are willing to work with us on this it’s going to allow us to roll this stuff out on the landscape and do a better job of saying where to put things and where not to,” he said.

CPW also has been conducting Piceance Basin research on the Roan Plateau west of Rifle to explore whether predation by bear and mountain lions has been impacting fawn survival rates. That controversial project has involved three years of removing up to 15 cougars and 25 bears a year through hunting and other means.

Some advocacy groups sought unsuccessfully to stop that research in court, and it is wrapping up. Anderson said it may be another year before the results of the study are released.

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