Wednesday, March 16, 2011


IMG_0475 Driving towards Las Vegas I noticed a coupe of overpasses that didn’t have any roads connected to them. That made me curious as to what their purpose was. And what a great idea it is. Here is part of the article I found documenting the first bighorn sheep to use the overpass.

Years of research, planning, and development showed early signs of success when video and still photographs captured two ram bighorn sheep crossing the recently completed wildlife overpasses near the Hoover Dam.

It marks a small, but significantly meaningful achievement that Arizona Game and Fish Department and Arizona Department of Transportation (ADOT) officials hope will minimize the impacts of desert bighorn sheep fragmentation through the Black Mountains and improve traffic safety.

When word arrived almost a decade ago of the planned widening of Highway 93 and the Hoover Dam Bypass effort, Game and Fish personnel pondered the fate of bighorn sheep throughout the range.

The Black Mountains bighorn sheep herd holds the largest contiguous desert bighorn population in the nation.

Fragmentation and habitat loss remain the leading cause of wildlife extinction. A four-lane highway in this area was going to increase the “barrier effect” for bighorn sheep, making it even more difficult for them to cross safely from one side of the highway to the other and raising concerns about the long-term sustainability of the herd.

With several underpasses already planned for wildlife, the problem wasn’t just whether the crossings would be in the right locations; it was whether those underpasses would be used by bighorn sheep.

What they discovered was that while many bighorn sheep approached the underpasses, few actually used them to cross the road. It was time to think like a bighorn. It became clear that these animals wanted to remain high, and crossing under a road wasn’t their preferred option. Bighorn sheep prefer to remain above potential dangers. Crossing under a roadway is avoided by bighorns because it is a great location for predatory animals.

So the overpasses were created and appear to be a success. I am so happy that somebody took the time and effort to think about man’s impact on these sheep and were able to come up with a solution.


  1. We saw some of them in Banff National Park too.

  2. Thanks for doing the research! My guess was it was a classic federally funded "bridge to nowhere". Now, we know!

  3. Neat! What a great idea, thanks for checking it out.

  4. those are some lucky bighorn sheep to have the 'funded bridge' to use!! tolls for them!!

  5. Amazing that they would think of these animals. Really good post! Thanks.

  6. Cool! Thanks for the info! Now when we finally get up there we will know what those bridges are when we see them.

    Maybe we'll even get lucky and get to see one in use!

  7. I was with Paul & Mary; I thought it was just unfinished from lack of financing. It's good to know otherwise.

  8. Very interesting Sandie. I've seen similar overpasses in the U.P. of Michigan for snowmobiles. Neat post!


  9. The NL Government could learn a lesson here. The number of fatalities in my home Province is astonishing due to Moose on the Highways !!

  10. Very cool post - you really did your research. I had also seen them in Banff National Park, but didn't know about them here.


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