Sage grouse fence mortality report attracts attentionWritten by Christy Hemken
Wyoming Game and Fish Department Sage Grouse Program Coordinator Tom Christiansen says in his Oct. 26 report that fence collisions have been anecdotally reported to cause sage grouse injury and mortality, but few efforts have been made to quantify the concern and publish results.
It was his desire to confirm reports either way that led Christiansen to begin a study in April 2005 a dozen miles northeast of Farson adjacent to the Little Sandy Creek on the Sweetwater/Sublette county line. The BLM range fence in the study is approximately 4.7 miles long.
“I had seen photographs and been shown instances of sage grouse in fences, and I wanted to know if it was an infrequent instance or if it happens more regularly,” says Christiansen. “That’s when I took a step beyond looking around to having the study site and comparing marked versus unmarked fences.”
The report shows from April 15, 2005 through Nov. 16, 2007 observers documented evidence of 170 bird strikes/mortalities and two pronghorn mortalities. Confirmed greater sage grouse accounted for 146 (86 percent) of the 170 strikes/mortalities.
Then, from Nov. 16, 2007 through May 14, 2009 approximately 1.54 miles of the fences was marked in .26 mile sections with FireFly bird diverters or homemade markers patterned after those used by the University of Oklahoma’s Sutton Avian Research Center.
During that period six surveys were conducted again, and the report says results suggest markers reduce bird fence collisions by 70 percent over unmarked sections.
“Seven bird strikes, all sage grouse, were documented in marked sections (4.55 strikes/mile) while 47 bird strikes (15.31 strikes/mile) were recorded in the unmarked sections,” says the report. ‘Thirty-six of these were confirmed sage grouse (11.73 strikes/mile). If only confirmed sage grouse data are compared, the markers appear to have reduced grouse mortality by 61 percent.”
“There are two extremes as a result of this data,” says Christiansen of responses to his report, which was initially just a summary of his findings to date requested by the Montana NRCS for cost-share programs. “Some people are saying every fence across the West is a hazard, but that’s not the case. On the other hand, we don’t want people grabbing markers for their fences and saying they’ve solved the sage grouse problem.”
After sending his preliminary findings to Montana he says the report went viral through email, generating a lot more attention than he anticipated.
Christiansen’s study reports not every fence is a problem. It says those that tend to cause problems typically include one or more of the following characteristics: 1) constructed with steel t-posts, 2) are constructed near leks, 3) bisect winter concentration areas, and/or 4) border riparian areas.
“Our study fence is in a high-density area for sage grouse, with large leks right around and a major wintering area. It’s probably the highest density of sage grouse in the world,” he says. “This data reflects a worst-case scenario.”
Of the study in general, Christiansen says he’s trying to keep it as real as possible, avoiding either extreme response.
Christiansen notes the future of his study will focus on gaining enough numbers and big enough sample sizes to draw statistical conclusions. “I want to have enough data and a big enough sample size to publish the report in a peer reviewed publication so it’s considered good science instead of an agency report, which is where it’s at now,” he says.
He’ll also work to fine-tune what kind of fence markers work best.
“What we’re trying to do now is find the best design for fence markers. We know there’s an issue, we know we can mitigate and what we’re using now works, but can we get by with less?” asks Christiansen.
He says the commercial product currently available is expensive, complete with high-tech glow-in-the-dark tape. According to product information, the FireFly Grouse Flight Diverter addresses collision problems in low light and fog conditions when installed on the top wire of a fence. The Snap-on FireFly diverter flips in the wind, reflecting sunlight and glowing after dark for 10–12 hours to increase visibility.
“We have persistent snow cover here for long periods of time, so the plain homemade white markers won’t really be visible, and that’s why we’ve added reflective tape to see how it works,” says Christiansen. “We need to test farther to see if we need it, and how much we need.”
Several thousand fence markers will be available for interested landowners at no cost come spring, after Christiansen and his team develop protocols for which fence areas are highest risk.
“We have enough information to move forward and make some markers available to ranchers that are willing to put them out,” he says. “We’ll prioritize fences, like those close to a lek or where there’s been a documented mortality.”
“We will have the criteria in place before spring fence-fixing season, and hopefully they’ll be simple and not bureaucratic,” he notes, adding that the markers are quickly and easily installed.
“Fences are a problem in some places, and they’re a problem we can fix,” he says. “We have so many sage grouse problems that are a struggle for cost-effective treatment, but these fence markers are something that works right away in problem areas.”