JWM study: Energy extraction impacting ferruginous hawks

New findings suggest that intensive oil and gas operations may be causing long-term local population declines in the ferruginous hawk (Buteo regalis), the largest species of American hawk, which soars in the open skies above the prairies, mountains and deserts where oil and gas development can be vigorous.

Funded by a North Dakota state wildlife grant, the study monitored breeding ferruginous hawks in two regions of the western part of the state undergoing different levels of energy extraction. The Bakken Shale to the northwest is an area of significant oil and gas activity where over 1,200 new wells were drilled between 2011 and 2013. The other research site, in the southwest, added fewer than 20 new wells during the same period.

The biologists drove along roads in these two areas, searching for the hawk’s huge, conspicuous nests. They counted the fledglings in these nests during the first year and the percent of nests that were re-used the following year.

Although there was no difference in reproductive success in the two areas, strikingly fewer nests were reoccupied in the Bakken Shale region, researchers found. Because the hawks usually return to the same nest year after year, the results were “startling,” said David A. Wiggins, a researcher with the Sam Noble Oklahoma Museum of Natural History at the University of Oklahoma and lead author of the paper, which was published this month in The Journal of Wildlife Management.

“Very few birds were coming back in the high-energy-extraction area relative to the low-intensity area, where almost all of them came back,” Wiggins said.

Wiggins and his colleagues concluded that oil and gas development could lead to long-term drops in local ferruginous hawk populations in areas such as northwestern North Dakota where oil and gas activity is heavy. The hawk nests from the west-central Great Plains to the Rocky Mountains and Great Basin.

Even so, Wiggins said, the ferruginous hawk adapts easily to nesting on artificial structures, which resemble wooden telephone poles cut in half and topped with a small platform to support nests. Land managers in other regions of the country have used these structures to increase the availability of nesting sites for the hawk. The study recommended installing the poles in the Bakken Shale, as well as in northwestern South Dakota and eastern Montana, where energy extraction may also be causing hawk population declines.

“Here you have a study that seems to point the finger at the energy industry in North Dakota,” Wiggins said. “They need to realize this is a good opportunity to carry out remediation work. That’s a little investment they could put their weight behind.”

TWS members can log into the member portal to read this paper in the February issue of The Journal of Wildlife Management. Go to “Publications” and then The Journal of Wildlife Management.