A Better Way to Cross the Road

Wildlife connectivity expert Dr. Patricia Cramer shares evolution in thinking on animal corridors, crossings

Nonhuman life — all other species besides Homo sapiens — too often pays the price of mankind’s relentless growth. As conservation advocate Logan Christian of the Mountain Lion Foundation said, “Human activity continues to fragment wildlife habitat, and roads are one of the biggest contributors to this problem, killing millions of animals in the United States every year.” One recent victim was a young mountain lion, P-104, killed by a driver on Southern California’s Pacific Coast Highway (PCH) on March 23.

P-104 had been fitted with a GPS radio collar just two weeks earlier after biologists captured him in the Santa Monica Mountains as part of a long-term study of area mountain lions to understand how they survive in a fragmented, urban landscape. Prior to his death, P-104 had crossed PCH several times. The 103-lb. cat was the 25th mountain lion, and eighth collared study cat, to be killed by a vehicle since the mountain lion study began in 2002.

Some hope to end at least some of the road carnage comes from Dr. Patricia Cramer, wildlife scholar and expert on wildlife connectivity, corridors and crossings, who has worked for nearly 20 years and in more than a dozen states in the transportation planning process with the goal of reducing wildlife-vehicle collisions. Through her studies in the 1980s, she realized how important connectivity was for animals.

In 1992, working on a PhD at the University of Florida, Cramer began modeling for the Florida panther, whose numbers were 200 in the state at the time, with none in northern Florida where she was living and focusing her work. At the time, modeling was not widely done, and she did her own coding. Cramer’s modeling was designed to predict how panthers moved on the landscape in order to see what land was most important to their survival. “You want to make sure when you re-introduce (a species), you’re not going to drop them off and they die, because you didn’t prepare the way for them.”

Unfortunately, Florida still has not released panthers in northern Florida, Cramer says, “largely due to the human component,” even though they could easily live there. Nonetheless, Florida has been a leader in building wildlife crossing structures, because of the endangered Florida panther (mountain lion or cougar) in the southern portion of the state.

Also while at graduate school, Cramer was part of a group that was successful in working with the Department of Transportation (DOT) in developing wildlife crossings in the Paynes Prairie Preserve, a wet prairie area, defined as a “herbaceous community found on continuously wet, but not inundated, soils on somewhat flat or gentle slopes between lower lying depression marshes, shrub bogs or dome swamps and slightly higher wet or mesic flatwoods, or dry prairie.”

Herpetologists had chronicled the loss of snakes and amphibians as a result of area highways. “We as scientists got together voluntarily and asked the DOT to put in wildlife crossings in the state preserve,” said Cramer, and they succeeded. Reaching out to politicians, writing letters to the editor and collaborating with DOT, the group was instrumental in the establishment of several crossings underneath the road that benefited numerous animals, including alligators and otters. As well, a three-foot tall concrete barrier was constructed roadside which kept animals from trying to navigate the road.

Cramer later completed post-doctoral work at Utah State University and worked in the early 2000s on a national project which allowed her to understand what work on wildlife crossings was being done across the country and to then promote wildlife crossings throughout the country.

The Evolution of Wildlife Crossings in the U.S.

In 1956, President Dwight D. Eisenhower signed the Federal Aid Highway Act of 1956 into law. Under the act, the federal government would pay for 90 percent of the interstate highways’ construction costs. Each interstate highway was required to be a freeway with at least four lanes and no at-grade crossings. As road building ramped up, says Cramer, there were some who were very cognizant of how development would impact wildlife, and they called for crossing structures. Cramer’s research found that the first underpass was constructed in Colorado on 1–70 in 1975, and the first overpass was in Utah over I-15. Over time, she says, they increased, but dropped off in the 1990s.

With the start of remote camera usage in the field around 2004, biologists could show in a very visually dramatic way how well crossings worked for animals. The public and members of DOTs were able to see mule deer, elk, porcupines, mountain lions, bears and other animals using the infrastructure. Once that evidence was available, Cramer says, crossings “really took off.” A highlight of Cramer’s work, after 15 years of research in Utah, came at a Utah DOT conference where part of her presentation included photos of animals at crossings. A planner said to her, “You asked us to build more wildlife crossing structures, and we didn’t know if they’d work. When you showed us all the pictures and movies of the animals using the structures, then we realized they did, and we started building more. You made a difference.”

With the cameras and resultant pictures — the proof of success — Cramer said there was a shift in mindset from about 2010 to 2015 of the importance of corridors and connectivity for wildlife that has continued to today.

Wildlife-Vehicle Collisions

On the ubiquitous roads of America, “Animals are hit, and people are hurt; it’s a phenomenon,” says Cramer, who describes it as “wildlife-vehicle conflict.” Not only are animals getting killed, but often they cannot even cross where they need to, because of too much traffic and fencing. In Cramer’s research of DOT wildlife crash data, categorized as “wildlife-vehicle crashes” and “animal-vehicle crashes” (includes dogs, cats, cows and horses), about 12 states don’t distinguish between the two types. Just looking at data for animal-vehicle crashes, she found annually about 347,000 crashes are reported, with the majority in the Midwest. If there is property damage only, costs may be a few thousand dollars per incident. If there is a human death, it may be millions of dollars. The total estimated cost per year for animal-vehicle crashes using federal highway crash values is $10 billion.

What We’ve Learned, What We Can Do

The science of ecology continues to develop, and there are ongoing findings about the needs of animals. For example, Cramer says, animals who live with people in urban/suburban areas are much more willing to go through long dark tunnels, compared with animals in wild landscape who want a short structure that’s very open. A decade of research has gone into identifying hot spots using GIS (geographic information system) to map locations in order to show DOTs where problems are to prioritize where funding should go to mitigate the largest problem areas for crashes with wildlife. This includes looking at both hotspots and corridors. The next phase Cramer hopes to see is DOTs and state/national wildlife agencies changing practices so that wildlife is always a consideration at the beginning of any planning process. Cramer points to Minnesota and Utah as good examples in this evolution. Utah recently codified including wildlife mitigation impacts to the items that the yearly UDOT report must include, making the tracking of crashes more transparent.

Utah is one of the few states that has built a stand-alone structure just for wildlife. But most of the time, Cramer says priorities are driven by when the next road project is coming up. “Big projects (10 miles or more) come up in a State Transportation Improvement Plan (STIT), which every state has, and we jump in on upcoming projects,” Cramer says. “We’ve been opportunistic, but we need to be more proactive.” This means recommending to the state where mitigation projects should be considered.

Among the least expensive efforts states can make to mitigate for wildlife-vehicle crashes are retrofits. As an example, New Mexico has added 8’ high wildlife exclusion fences to existing structures that are large enough to accommodate mule deer. Another low-cost improvement is to upsizing culverts which already are in place. Simply by enlarging these, more animals can pass through.

That the evolution has progressed is evident too in the infrastructure legislation signed into law by President Biden in November, which includes the first-ever dedicated funding for wildlife crossing structures and other measures to improve habitat connectivity. As well, the largest and most expensive wildlife crossing is finally breaking ground in California this month over the 101 freeway, one of the busiest in the country.

While the push to ensure that wild and domesticated animals always are considered in planning roadways, including expansions, upgrades and new roads, with those responsible for these operations, it’s essential for stakeholders — citizens — to let their state officials and wildlife managers know that keeping wildlife protected is important to them, and building crossings and corridors is part of this.

The Mountain Lion Foundation’s discussion with Dr. Cramer is here.

Maria Fotopoulos writes about the connection between overpopulation and biodiversity loss, and from time to time other topics that confound her. Contact her on FB @BetheChangeforAnimals.