How Do Animals Safely Cross a Highway? | Hacker News Reader

How Do Animals Safely Cross a Highway?

nytimes.com

35 pointsmhb15 comments

“I want everyone to be super excited about wildlife crossings, but I don’t want people to forget that a wildlife crossing is like a Band-Aid,” said Trisha White, an environmentalist who was integral in moving wildlife crossings from the fringes to the mainstream in the United States. The structures, she emphasized, can only fix a small part of the road’s damage to wildlife habitat.

“The road,” she said, “is like a wound.”

That’s a thing that can be forgotten when comparing roads to rail - they both cut across the countryside but the equivalent number of trains interrupt the landscape less - for a single “front” it stretches quite long.

I wonder if predators will take advantage of these bridges.

>but the equivalent number of trains interrupt the landscape less

It's not so cut and clear. Anywhere that isn't super flat you're going to need to cut into and build on top of the landscape a ton because of the low maximum grade inherent to steel wheels on steel rails. This comes with retaining walls, runoff control and all the other features required to keep the landscape from quickly reclaiming the rail bed. These features have impact on the surrounding ecosystems but less visibly than roadkill.

That's a good point - it'd be interesting to see what percentage of railway is "navigable" by wildlife vs blocked - even in the mountains the railways often follow riverbeds or cuts alongside mountains.

Outside the US railways have to be fenced along their length.

At least in the Nordics highways, too, are completely fenced with the fences leading to animal crossing bridges/tunnels. Don't want a full-grown elks trying their luck and crossing a highway, that would be a recipe human fatalities too.

If you ride a bicycle on the roads in Texas it's pretty bleak. You can expect to see 4-5 dead animals in any mile. The buzzard population is doing well because we don't pick up roadkill anymore. But it puts into perspective how many animals die from car collisions. It's like riding along a 100 foot wide, 200 mile graveyard.

Is this at least a little outside urban areas?

The same is true in Australia, mainly with kangaroos.

Texas geography is a bit weird. Everything is 20-30 miles apart with a bunch of little small communities. There are huge sprawling ranches and private reserves all over the place. Very little public land too. Herds of 100+ whitetail deer hang out in the city parks at night. Armadillos and opossums are everywhere. I'm sure in city centers it's a bit different because there isn't as much wild land. But even in the outskirts of Austin you will see tons of ranch land and 5 acre homesteads.

It's pretty cool to ride at night and see the wildlife living alongside housing tracts and 7/11 stores. Although if you like gardening you can bet a deer will eat your roses before too long. All the gardens look like maximum security prisons!

How do they get wildlife to use these? Do they just line the road with fences to funnel animals into the purpose-built crossings? What length of road can one of these crossings support? Are there any measures for how effective these crossings are at reducing wildlife collisions? These things sound good on paper but I wish the article more information to back them up.

EDIT: Another commenter pointed out the article does provide a metric for the effectiveness of these crossings in the first paragraph: 90%.

Yes, they put up fences to funnel animals. There are indeed measures for how effective they are.

It sounds like you're bothered that this article for popular consumption isn't an entirely different piece about the same topic.

I'm bothered that this article appears to advocate for more of these crossings without including any useful information on the subject. It's making an argument with no data to back it up and few details about how these crossings even work.

The article at least cites some research about how many injuries and deaths are caused by wildlife collisions, but it doesn't give any information about how much animal crossing infrastructure helps with that. The videos are cute, but not very informative. Aside from that, it's mostly just qualitative assessments from a few biologists and environmentalists.

Why should the kind of information I'm asking for be absent from an article for "popular consumption"? I'm not asking for a research paper. Would mainstream readers be turned off by sentences like "Tall fences keep wildlife off the roads and funnel them towards structures which allow them to cross safely," or "A large crossing like the one pictured above can provide safe crossing for animals along a 20 mile stretch of road," or "After a crossing is built, traffic collisions with wildlife usually decrease by 50% to 80% according to the ACME Research Group"?

Maybe the lack of substance to this article has something to do with why it fell off the front page so quickly.

In the first paragraph:

> Collisions have dropped by roughly 90 percent.

No link to the source of this number though.

Thank you! That's the big piece of info I was looking for. I can't believe I missed that.

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