By Doug Leier
Even as a lifelong North Dakota hunter, angler, former game warden and veteran (old) biologist, there are plenty of times when my colleagues and agency make me smile and think “WOW, now that’s cool.”
Take for instance a few years back when North Dakota’s first big game crossings was perceived, designed and implemented.
Sure, we’re all familiar with the age old “deer crossing” signs warning of traditional areas where history has shown a pattern of deer-vehicle collisions. Creating an awareness for the potential is a huge step in reducing property damage to vehicles and potential injury and even death.
I’m sure you’ve all heard the lighthearted joke. How do the deer know they are supposed to cross there? Funny but true.
In the badlands of western North Dakota, the combination of high volume traffic, rugged terrain and even bigger big game such as moose and limited populations of bighorn sheep, the wildlife crossings essentially went from the equivalent of a warning sign to a bypass.
You’ve seen truck bypasses to reduce traffic through urban areas? Think of wildlife crossings in a similar way, but unlike humans who are redirected, the wildlife must be guided with something other than a simple sign.
“The number of animals that have successfully gone through the crossings so far is very encouraging and we realize that we’re probably going to see an even higher number of animals use them in the future,” said Bruce Kreft, North Dakota Game and Fish Department resource biologist. “As the Game and Fish Department, we want to protect the animals, help fulfill their life cycles and allow them safe passage. And from a motoring public standpoint, these safe crossings translate to the possibility of hundreds of fewer wildlife-vehicle collisions.”
North Dakota’s first wildlife underpass was constructed on U.S. Highway 85 on the Lewis and Clark Wildlife Management Area near Williston, utilizing design criteria for moose. The second crossing, also on U.S. Highway 85 south of the Long X Bridge near the North Unit of Theodore Roosevelt National Park, was completed a few years later in 2021 to accommodate bighorn sheep movements, as well as the comings and goings of mule deer and other animals.
To monitor wildlife movement at the sites, Kreft said trail cameras were installed on both sides of the crossings. While cameras identified successful navigation through the structures, they also identified “deflections,” or animals that simply approached the crossings but didn’t fully commit.
Some findings from the Long X crossing:
This crossing experienced 386 and 989 mule deer approaching the crossing in 2021 and 2022 with a successful crossing rate of 91% and 93%, respectively. The crossing was only monitored for 143 days in 2021, resulting in fewer animals approaching compared to 2022, but had similar animals crossing per day of monitoring.
Bighorn sheep movements resulted in 58 and 171 animals approaching the structure in 2021 and 2022, with successful crossing rates of 81% and 89%, respectfully.
Both mule deer and bighorn sheep experienced an increase in crossing success from 2021 to 2022. This likely is contributed to behavioral learning and hopefully the start of generational learning of fawns and lambs.
“A lot of times with a new structure there’s generational learning that has to occur, that this structure is there for them and it’s a safe passageway for them to get to the other side,” Kreft said. “Typically, it takes about 3 to 4 years to really see the full degree of crossing for those animals. The ewes have to teach their lambs and the does have to teach their fawns that it’s a safe way to get to the other side for breeding purposes, feeding purposes, for whatever.”
It’s one of those projects I think we can all say, “well done.
Comments