Wildlife and Ecosystems

Across the country, state departments of transportation provide support to a wide variety of efforts aimed at supporting numerous bird species and their habitats.

[Above photo by the NCDOT]

For example, in July and August every year, the North Carolina Department of Transportation temporarily lower speed limits from 55 mph to 20 mph on the William B. Umstead Bridge – locally known as the old Manns Harbor Bridge – at dusk and dawn during the roosting period of purple martin bird flocks.

NCDOT noted in a statement that it has collaborated with the Coastal Carolina Purple Martin Society since 2007 to educate the public about the purple martin flocks, to protect both the birds and motorists. From late July through August, the west end of the bridge becomes home to as many as 100,000 purple martins as they prepare for their annual migration to Brazil. The birds roost under the bridge at night, departing at dawn to feed and returning at sunset. The flock is so large during its peak that it is visible on radar.

To protect those birds, NCDOT activates flashing lights and lowers the speed limit on the bridge at sunrise and sunset. Law enforcement monitors speed limits on the bridge to allow motorists and birds safe passage across the sound. Since NCDOT installed those lights and lowered speed limits, the Coastal Carolina Purple Martin Society has seen a dramatic decline in bird deaths around the bridge.

On a broader basis, NCDOT initiated a mitigation program in April operated by its Division of Aviation to reduce the risk of wildlife hazards by providing a variety of training and support options for both airports and aircraft.

The agency said North Carolina airports average at least one bird or other wildlife strikes upon aircraft per day, which can cause significant damage. For example, in 2018, an aircraft landing at a general aviation airport sustained more than $800,000 in damage when it struck two of six white-tailed deer crossing the runway.

“Flocks of birds taking flight, deer crossing runways, and other such hazards can cause serious damage to property and even loss of life,” noted Rajendra Kondapalli, the program’s manager, in a statement. “Our program focuses on reducing that risk and increasing safety for aircraft that fly in and out of airports across our state.”

Meanwhile, the Idaho Transportation Department helped Girl Scout Troop 1806 and the Idaho Department of Fish and Game (IDFG) install homemade birdhouses near the US-95 McArthur Lake project south of Naples.

ITD Project Manager Carrie Ann Hewitt has consulted IDFG biologists through the design of the project, which includes realigning one mile of the highway near the lake to make the existing curves safer for drivers and to elevate the highway where it dips down to the water. Elevating US-95 will also allow wildlife to pass underneath to access the IDFG McArthur Lake Wildlife Management Area, ITD noted in a statement.

The agency expects to start construction on this roadway project in 2023 and 2024, with tree thinning starting in 2022 to prepare for the road’s realignment.

Hewitt – a co-leader for the Girl Scout troop – has been researching the habitat needs of the mountain bluebird, flocks of which reside near the project, and reached out to IDFG to see about improving its habitat.

“Mountain bluebird populations are struggling,” Hewitt noted. “The girls found that cowbirds actually swap out eggs with the bluebirds, and the bluebirds unknowingly hatch the wrong offspring.”

The troop built 18 birdhouses with entrances too small for the cowbirds to prevent that from happening, with IDFG suggesting that they install them near McArthur Lake due to the recent thinning, along with another site near Boundary Creek.

A research document just released by an international pool-funded study led by the Nevada Department of Transportation provides an “authoritative review” of the most effective measures to reduce animal-vehicle collisions, improve motorist safety, and build safer wildlife crossings.  

[Above image by the Nevada DOT]
With as many as two million collisions with large mammals in the United States leading to approximately 200 human deaths every year, the review compiled, evaluated, and synthesized studies, scientific reports, journal articles, technical papers, and other publications from within the United States and beyond to determine the effectiveness of 30 different mitigation measures.

Ultimately, the report provides best management practices to reduce animal-vehicle collisions, increase habitat connectivity, and implement cost-effective solutions. Key findings include:

• The most proven effective measures to reduce animal-vehicle collisions by over 85 percent while providing habitat connectivity remain wildlife fences in combination with wildlife overpasses and/or underpasses. Researchers now know that these measures must cover at least several miles to reduce collisions significantly with large mammal species.
• Traditional warning signs, educational campaigns, reducing posted nighttime speed limits, and other measures are in general less than 50 percent effective. Some mitigation measures are at least 50 percent or greater effective in reducing animal-vehicle collisions, including roadside animal detection systems, nighttime lighting, and reducing the size of the population of wildlife species involved. However, none of those reduces a road’s “barrier effect” for wildlife; some even increase the barrier effect.  
• No detailed study examines the ability to reduce animal-vehicle collisions with vehicle-based detection technology in highway situations – especially where connected and autonomous vehicles or CAVs are concerned. While there are likely benefits of this technology for reducing collisions with large mammal species, the sensors typically do not detect smaller species. Furthermore, this technology does not reduce the barrier effect of the road and traffic for wildlife.

Nova Simpson, a biological supervisor and large mammal mitigation specialist with Nevada DOT, helped manage the study.  Simpson believes it will help state and federal transportation, land management, and wildlife agencies optimize efforts to reduce animal-vehicle collisions. 

“This pooled fund study provides a very unique opportunity to synthesize current knowledge from the U.S., Canada, and internationally,” noted Simpson in a statement. “It will improve the cost-benefit analyses of mitigation measures, field test improved designs and technologies; and coordinate and provide outreach to transportation, land management, and wildlife agencies and their stakeholders. Ultimately, these efforts will help in the reduction of wildlife-vehicle collisions across the United States.”
Nevada DOT has already installed many roadway improvements to reduce potentially dangerous animal-vehicle collisions statewide. For example, in February, the agency installed four-foot high livestock fencing along stretches of U.S. 50 between State Route 341 and Chaves Road in Dayton, NV, to reduce horse-vehicle collisions.

Nevada DOT also worked with the Nevada Department of Wildlife to install nine safety crossings on Interstate 80 between Wendover and Wells and U.S. 93 north of Wells in the northeastern portion of the state four years ago.

That project – which garnered a 2019 Environmental Excellence Award from the Federal Highway Administration – covered wildlife overpasses with native soil and vegetation to replicate the natural environment, with roughly 60 miles of eight-foot-high fencing installed along both sections of the roadways redirecting and encouraging deer, mules, and other animals to use the crossing points.

The agency added that it has also installed 400 miles of tortoise fencing and 19 tortoise underpass/culvert crossings on the U.S. 95 and U.S. 93 in southern Nevada to reduce wildlife-vehicle collisions and tortoise road mortality.

Routine highway maintenance conducted by a North Carolina Department of Transportation work crew turned into one “honey” of a rescue mission in early June.

[Above photo by NCDOT]

NCDOT Division 9 maintenance crews were working on storm drain repairs and cutting down dead trees along U.S. 52 and discovered something unusual: Two honey-making beehive colonies nestled within one of the dead trees.

An online search for honeybee resources led the crew to “Miss Humble B’s Hive,” a local organization affiliated with the Forsyth County Beekeepers Association.

The group came to the highway work site and collected one live queen, some honeycomb, and most of the hive – relocating the bees to a small wooden hive in their own backyard. The bees rescued from the badly damaged hive at the U.S. 52 site will remain in the wooden hive until the queen starts laying eggs and the colony has enough bees to protect a larger hive, NCDOT said

While honeybees are not listed as an endangered species, their numbers along with several other species of bees have been on the decline over the past few decades – largely attributed to climate change, harmful chemical use, and habitat loss, among other factors. The loss of these important pollinators could have a significant impact on fruit and vegetable crops and wildflowers, noted Tiffany Williams-Brooks, who owns Miss Humble B’s Hive with her husband, Derek.

“When we look at the honeybee population, it is definitely on a decline,” she said in a statement. “When it comes to the number of hives beekeepers have nationally, the number has declined by at least 50 percent over the last several years.”

In terms of the rescued hives, Williams-Brooks said she could not find new broods and eggs. “We found open queen cells where new queens had emerged at some point,” she explained. “There were a lot of bees flying around, but they may not have belonged to that hive. We are in a nectar dearth, [or] scarcity of nectar, so often we will see bees coming in to take honey from other hives.”

Still, NCDOT Transportation Supervisor Kenny Butler – who, along with colleagues Greg Dellacona and Danielle Herrin, located Miss Humble B’s Hive to rescue the bees found along U.S. 52 – considers this bee relocation a success. “It was simply the right thing to do,” he emphasized. “We’re proud of the work our people do and are appreciative of the effort they take to just do the right thing.”

State departments of transportation across the country are engaged in a variety of efforts to preserve pollinator habitats, both for insects and specific plants.

For example, in October 2021, the Georgia Department of Transportation and the Georgia Association of Conservation Districts or GACD began installing 15 pollinator habitat sites in designated locations as part of a joint effort to educate state residents about the important role “pollinators” such as bees, butterflies, and other insects play in Georgia’s agricultural sector.

“This partnership provides Georgia DOT with the unique opportunity to create a safe and beautiful place for families and travelers to get up close and personal with the wildflowers and grasses [to] learn about how they impact the world around us,” explained Felicity Davis, a landscape architect manager with the Georgia DOT, in a statement.

The Tennessee Department of Transportation participated in a similar endeavor with the Tennessee Department of Environment & Conservation (TDEC) and Tennessee Department of Agriculture as those three agencies formed a partnership in 2019 to support 64 acres of “pollinator meadows” at eight state parks.

Each blooming meadow contains a mix of nectar-bearing plants and milkweed, which sustain pollinators such as bees, moths, butterflies, birds, and small mammals such as bats. Those meadows also assist with TDEC’s Honey Project, which allows the public to purchase honey harvested annually within state parks across Tennessee.

The Tennessee DOT also recently launched a series of animated videos about pollination and pollinator species featuring the narrator “Polli the Tennessee Bee” to educate children about the process of pollination, its importance, and the pollinator species native to Tennessee.

It’s all part of “re-envisioning” the role state DOTs can play in turning roadway rights-of-way into protective habitats, Matthew Quirey – a landscape design and research fellow with The Ray, which is a public-private venture devoted to roadway technology testing along Interstate 85 in West Georgia

In a July 2021 episode of the Environmental Technical Assistance Program or ETAP Podcast, Quirey explained how state DOTs can view such roadside “landscapes” are “habitat assets” instead of maintenance burdens.

“In general, we are thinking more about how right-of-ways are being redesigned to bring habitats back together – to serve not just as transportation corridors but ecosystem corridors as well,” he explained. That includes how right-of-ways can serve as habitats for pollinators, and contribute to better stormwater management in order to lessen pollution risks for nearby streams and rivers – incorporating sustainability and resiliency factors within more “environmentally sensitive” planning and design processes, Quirey said.

An initiative to “Give BIRDS the ROW” in terms of creating big habitats in highway rights-of-way is expanding across Illinois – with new support from the Illinois Department of Transportation.

[Above photo by the Illinois DOT]

The program originated with the installation of birdhouses for “prothonotary warblers” along the Lost Bridge Trail near Illinois DOT’s headquarters in Springfield, IL. The program’s goal is to restore diverse bird species on rights-of-way or ROWs under the control of Illinois DOT. In its latest effort, a group of Illinois DOT employees recently helped install bluebird houses, provided by the McHenry County Audubon Society, at the Coalfield Rest Areas on I-55 near Litchfield in Montgomery County.

Posted in short-grass, open-yard habitats, these birdhouses not only provide a resting spot for bluebirds but also attract other native bird species.

“In total, four bluebird houses have been posted so far: two at the northbound Coalfield Rest Area and two at the southbound Coalfield Rest Area,” said Jarod Hitchings, who works as a photogrammetrist for the agency, in a statement. [Editor’s note: “Photogrammetry” is the use of photography in surveying and mapping to measure distances between objects.]

“The in­stallation of more houses are planned for prothonotary warblers along the Spoon River and for bluebird houses at rest areas and other appropriate short-grass, park-like habitats maintained by Illinois DOT,” he said.

Fellow Photogrammetrist Brenda Anderson joined Hitchings – who both work for the agency’s bureau of design and envi­ronment – to install those birdhouses. They received assistance from Illinois DOT District 6 Roadside Management Specialist Mike Staab and Junior Construction Inspection Technician Marcell Lare, Roadside Maintenance Manager Stephanie Dobbs, District 8 Acting Rest Area Manager Jacob Cuff, and District 5 Roadside Manager Scott Hall.

Illinois DOT Design and Environment’s Bicycle and Pedestrian/ADA Policy Engineer Steve Letsky also donated handcrafted birdhouses he built on his own for this effort.

“Operations and Design and Environ­ment have worked well together to pro­mote declining bird species,” Hitchings noted. “Partnering with the district offices, we have truly made this a statewide effort to promote a healthy environment for our feathered friends. Birds are a sentinel species and are a signal that the natural landscape is healthy for all wildlife.”

“We hope to grow this program and install a variety of houses at different locations as the habitat and range indicate,” Dobbs added. “In the future, if interesting species find homes on our right of way, we would like to do a webcam or something similar to share it with employees and the public.”

State departments of transportation across the country are involved in a number of efforts to protect and preserve bird species where possible.

For example, a mitigation program operated by the North Carolina Department of Transportation’s Division of Aviation aims to reduce the risk of wildlife hazards by providing a variety of training and support options for both airports and aircraft.

“Flocks of birds taking flight, deer crossing runways, and other such hazards can cause serious damage to property and even loss of life,” noted Rajendra Kondapalli, the program’s manager, in a statement. “Our program focuses on reducing that risk and increasing safety for aircraft that fly in and out of airports across our state.”

Meanwhile, the Minnesota Department of Transportation recently helped test ultrasonic bat “deterrence devices” at two bridges to help keep the mammals away from such structures when they undergo maintenance and/or repair activity.

The agency noted that bats like to roost in bridge expansion joints and temporarily preventing such roosting during bridge maintenance repair activity typically requires installing physical barriers that are often difficult to establish effectively, due to the design characteristics of many structures.

More importantly, the Minnesota DOT does not necessarily want to keep bats away permanently from its bridge as they provide safe roosting areas. Thus, the agency worked with the Minnesota Department of Natural Resources and the U.S. Fish and Wildlife Service for the last two years testing battery-operated ultrasonic deterrence devices that reduce bat activity at bridge sites when activated but ensure a quick return of bat roosting activity when deactivated.

The Wyoming Department of Transportation recently received a 2022 Environmental Excellence Award in the category of Ecosystems, Habitat, and Wildlife from the Federal Highway Administration for its role in the Snake River Bridge reconstruction and wildlife crossing integration project. The award is one of 14 conferred by FHWA nationwide in various environmental categories. 

[Above photo by the Wyoming DOT]

Wyoming DOT – along with the Wyoming Game and Fish agency, Teton County, and other community organizations – designed a project for the replacement of a critical bridge on Wyoming Highway 22 over the Snake River, near Jackson, and expanded it to accommodate local and migrating wildlife within the Greater Yellowstone National Park ecosystem.

FHWA cited Wyoming DOT’s exemplary “achievement and extensive stakeholder collaboration, community engagement, and environmental considerations” in granting the award.

The wildlife underpasses and three additional wildlife crossings built by this project should provide for “safer movements”, especially for large animals such as moose, elk, and deer. 

The agency is also implementing additional improvements that will enhance recreation and natural resource education in the nearby Rendezvous Park with work that will include increasing wetlands along ponds, constructing a boardwalk, and making a swimming hole deeper. 

Construction on this project should begin in the spring of 2023, Wyoming DOT noted.

This follows a joint effort by Wyoming DOT and the Wyoming Game and Fish agency launched in 2019 that committed a combined $2.5 million toward installing wildlife crossings along US 189 in southwest Wyoming – known as the “Dry Piney” project – to help reduce wildlife-vehicle collisions.

The purpose of the improvements is to support positive public interaction with the natural environment while addressing the needs of the ecosystem, noted Wyoming DOT Director Luke Reiner in a statement.

“We appreciate the recognition and affirmation from the FHWA that this is a special project that will benefit not just the transportation of motorists but of wildlife, too,” said WYDOT director Luke Reiner. “I am grateful to our partners who were instrumental in shaping this project into an award-winning success.”

State departments of transportation in many parts of the country are working to improve wildlife crossings across a variety of transportation projects.

For example, the Colorado Department of Transportation and the Colorado Parks and Wildlife agencies completed wildlife underpasses along a rural stretch of Interstate 25 between Colorado’s two largest cities, Denver and Colorado Springs, in October 2021.

That wildlife mitigation system is part of a $419 million transportation improvement project – known as the I-25 South Gap project – that aims to improve safety and travel on 18 miles of I-25 south of the Denver metropolitan region; a route that more than 87,000 motorists use on a daily basis.

In February, the Nevada Department of Transportation began closing stretches of U.S. 50 between State Route 341 and Chaves Road in Dayton, NV, to install high livestock fencing on both sides of the highway largely along rural roadway stretches to reduce vehicle-horse collisions.

The Nevada DOT is also placing roadway lighting on the highway at the end of each fenced section for enhanced visibility for motorists.

In addition, in April, the Oregon Department of Transportation recently received a special one-time allocation of $7 million in general funds from the Oregon legislature to invest in wildlife corridor projects statewide. The Oregon DOT said it has had “great success” with wildlife undercrossing structures in recent years, with five crossings built to date in the state, all on U.S. 97, leading to an 86 percent reduction in wildlife-vehicle collisions.

A mitigation program operated by the North Carolina Department of Transportation’s Division of Aviation aims to reduce the risk of wildlife hazards by providing a variety of training and support options for both airports and aircraft.

[Above photo by NCDOT]

The agency said North Carolina airports average at least one bird or other wildlife strikes upon aircraft per day, which can cause significant damage. For example, in 2018, an aircraft landing at a general aviation airport sustained more than $800,000 in damage when it struck two of six white-tailed deer crossing the runway. On top of that, the Federal Aviation Administration Wildlife Strike Database​ – which tracks wildlife strikes – estimates that only one in five strikes are reported, which adds up to a significant threat to property and life.

“Flocks of birds taking flight, deer crossing runways, and other such hazards can cause serious damage to property and even loss of life,” noted Rajendra Kondapalli, the program’s manager, in a statement. “Our program focuses on reducing that risk and increasing safety for aircraft that fly in and out of airports across our state.”

The wildlife program, offered through a cooperative agreement with the Wildlife Services Division of the U.S. Department of Agriculture, provides five regional trainings and assessments of one-third of the state’s 72 public airports each year. It also provides “quick-response” management activities for airports experiencing wildlife hazards. 

That “quick response” program provides both proactive and reactive management, NCDOT said, such as harassing geese, gulls, raptors, and other birds using pyrotechnics, habitat management, and, if warranted, lethal control. The USDA may live trap and relocate hazardous raptors such as hawks and falcons to suitable habitats miles away from the airport.   

Trainings provide instruction and hands-on practice in identifying common animal species, potential habitats, and food sources that attract animals to airports and methods to deter wildlife using safe methods from interfering with airport operations.

The wildlife management assessments offered through the program include an airport site visit to conduct a bird and mammal hazard survey and an assessment report with wildlife observations, habitat attractants, and mitigation recommendations based on USDA’s observations. This can range from proper grass height, tree removal, proper fencing, and agriculture near the airfield. “These trainings are very important because they help the airports better understand the hazards on their airfields and what they can do to mitigate them, short-term and long-term,” noted Chris Willis, western district supervisor for the USDA Wildlife Services in North Carolina, who provides the training. “It also helps the aviation [divisions] understand the needs the airport may have or what hazards exist.”

The Arizona Department of Transportation recently illustrated in a blog post how ‘biomonitor’ teams from Northern Arizona University or NAU help the agency’s crews find and relocate endangered species – including snakes, birds, and fish – from construction sites.

[Above photo by the Arizona DOT]

Specifically, the biomonitor teams train construction workers and others involved in transportation projects to identify any endangered species and what to do if they come across one. The teams also monitor construction activity and help safely remove any endangered species out of harm’s way. 

For example, for an Arizona DOT project to protect the I-17 Verde River Bridge footings – set to wrap up later this spring – agency crews built earthen bypass channels to contain river flow, allowing them to work outside of the river area safely. Simultaneously, the biomonitor team removed all fish from pools that required filling in, while also rescuing fish stranded during river relocation work.

Next, the biomonitor team identifies the endangered species it finds, photographing and measuring them, and then releases them back into the Verde River downstream from the construction area.

“The relocation distance varies, but it’s typically about 50 to 150 yards from the capture point,” noted Dr. Erika Nowak, an assistant research professor at NAU, who heads up the biomonitor team for the I-17 Verde River Bridge project.

“We don’t want to release the animals too far away, as moving them out of their home range can disrupt their behavior, cause them to become disoriented, and thus more likely to die,” she added.

This is one of several efforts by Arizona DOT to preserve both animals and plants considered endangered species.

The agency recently completed a bridge replacement project near Globe, AZ, which triggered the return of an endangered species of cactus transplanted and preserved by the agency during the project’s four-year timeline.

The U.S. 60 Pinto Creek Bridge is home to the endangered hedgehog cactus, which grows only within a several-mile radius of the site. About a foot high, usually covered in spines and often with red flowers at the top, the species is listed as endangered by the U.S. Fish and Wildlife Service and is protected under Arizona law. When the bridge replacement project began in 2018, a team comprised of biologists from the Arizona DOT and from the Desert Botanical Garden in Phoenix safely removed 34 cacti potentially affected by the construction work, then nurtured and propagated, replanting 61 total cacti in early March.

The Oregon Department of Transportation recently received a special one-time allocation of $7 million in general funds from the Oregon legislature to invest in wildlife corridor projects statewide.

[Above photo by the Oregon DOT]

The Oregon DOT said it has had “great success” with wildlife undercrossing structures in recent years, with five crossings built to date in the state, all on U.S. 97, leading to an 86 percent reduction in wildlife-vehicle collisions.

Cidney Bowman, the agency’s wildlife passage coordinator, said in a statement that Oregon DOT plans to use that one-time funding not just to help fund wildlife crossing construction but also to fund studies, retrofit existing structures, and pay for research into new wildlife detection technology.

She added that, while this new funding will go a long way toward making our highways safer, Oregon DOT’s goal is to have yearly dedicated funding for wildlife corridor needs similar to how the state funds its fish passage program.

A state report issued in 2020 indicates that Oregon needs $22 million to $35 million in “immediate” funding to support wildlife crossing projects statewide.

Other states – especially in the western parts of the country – are beefing up investments in wildlife passage programs and infrastructure. For example, California and Utah both have 50 wildlife passage structures, Nevada has 23, and Colorado leads the pack at 69.

Recently, the Colorado Department of Transportation and ABCO Contracting began installing three miles of new “high deer” fencing and earthen big game ramps along US Highway 24/285; a $2.26 million project that should wrap up in early September.

Additionally, the high deer fencing will tie into existing drainage structures that are sufficiently large enough to offer crossing locations for large game. The new fencing will funnel wildlife to these locations, an important aspect of this project site, purpose, and design noted Julie Constan, the agency’s regional transportation director.

“Wildlife-vehicle collisions make up approximately 60 percent of the total crashes along this stretch of highway,” she said in a statement. “The investment made to install the fencing will show us a tremendous benefit. Studies have shown that big game-vehicle collisions are expected to go down by at least 80 percent with the aid of fencing features.”