A pair of new exhibits at the Tennessee Aquarium funded by the grants from the Tennessee Department of Transportation illustrate how microplastics and other roadside trash can negatively affect the health of the ocean as well as rivers, lakes, and streams.
[Above photo by the Tennessee Aquarium]
The new exhibits – housed in the Aquarium’s “River Journey” and supporting the Tennessee DOT’s “Nobody Trashes Tennessee” litter reduction campaign – includes actual debris taken from the banks of the Tennessee River
The exhibits demonstrate the connection between land-based pollution and aquatic ecosystems through “touchless” interactive elements, informative videos, and an exhibition of invasive aquatic wildlife such as a Northern Snakehead and Grass Carp. Those non-native fish are housed in one of the exhibits, swimming alongside examples — some of them 3D-printed — of common roadside debris such as tires and car batteries, which can wreak havoc on aquatic systems.
“The connections between roadside litter, water quality and aquatic systems cannot be understated,” said Shawn Bible, Tennessee DOT’s beautification office manager, in a statement.
“The ‘Nobody Trashes Tennessee’ campaign aims to educate citizens on the impact of what may be perceived as a minor issue for the state,” Bible added. “In reality, the state spends more than $19 million each year to clean up the more than 100 million pieces of litter on our roadways. We are pleased to partner with the Tennessee Aquarium on these interactive exhibits.”
The exhibits help visitors visualize how trash can imperil aquatic ecosystems and impact waterways that millions rely on for recreation and drinking water, while also demonstrating how changes in behavior on land can benefit the health of nearby waterways, explained Dr. Anna George, the Aquarium’s vice president of conservation science and education.
“Anything that is on land moves into our waterways,” Dr. George said. “If a piece of litter is thrown onto a street, wind might carry it to a stream or river. It might get washed or blown into storm drains and deposited in the nearest body of water. It is a safe assumption that any debris on land has a good chance of winding up in our water.”
According to the National Oceanic and Atmospheric Administration, 80 percent of garbage found in the ocean comes from inland sources, such as leaked automotive fluids and littering. “So even though the [Tennessee] Department of Transportation might seem like an odd partner for an aquarium, there’s a fundamental connection between activity on land and the health of waterways,” Dr. George noted.
The construction of the new Rock Creek Bridge to replace a culvert on US-20 recently won an engineering excellence award from the American Civil Engineers Council of Idaho – an award shared by the Idaho Transportation Department (ITD) and Jacobs Engineering.
[Photo by the Idaho Transportation Department.]
The new bridge now allows wildlife to pass under the highway, reducing the risk of possible collisions involving wildlife and vehicles on the roadway. The ITD added in a statement that this particular section of US-20 witnessed 64 vehicle-wildlife collisions over the last five years, which totals a “societal cost” of approximately $2 million when adding together the cost of vehicle repair or replacement, medical bills, and increased insurance rates – not to mention the cost to wildlife.
The project also allowed the ITD to restore the streams forded by the new bridge to a more natural condition, which in turn should positively benefit the surrounding ecosystem by encouraging safer fish passage under the highway.
Building a bridge also reduced the impact on the local environment versus replacing the existing multi-plate culvert with a similar culvert design, ITD added.
This was one of ITD’s first projects incorporating ‘fabric encapsulated soil lifts’ into a design – a way to ensure streambank stability as water levels rise and fall while still promoting vegetative growth. The project has already improved the environment while enhancing the safety and the natural beauty of the project area, ITD added. Just a few months after construction, the agency spotted fish swimming upstream to spawn, while noting several deer – and a moose – traveled along the channels under the bridges.
The Transportation Research Board recently highlighted a bevy of resources available to state departments of transportation to support monarch butterfly habit and migration support efforts.
[Photo courtesy of the Virginia Department of Transportation.]
The report also includes several tools and decision-support mechanisms to optimize habitat potential in a manner that is compatible with the continued operation and maintenance of the roadside.
TRB noted in a blog post that a 2014 Presidential Memorandum “influenced” its recent research on monarch butterfly conservation – a memorandum that encouraged the Federal Highway Administration to work with state DOTs, transportation associations, and roadside managers as part of a holistic approach to promote the health of pollinators.
TRB added that forthcoming research from NCHRP will help craft a “guidebook” to help decision-makers tailor programs to maximize insect pollinator habitats along roadways. That guidebook will consider additional public benefits, roadway characteristics, and safety, as well as the geographical, adjacent land use, and ecological contexts. Butterflies and other pollinators are only a small subset of the wildlife benefiting from informed transportation planning.
In April, the U.S. Fish and Wildlife Service and the University of Illinois-Chicago signed what they called a “historic agreement” to encourage transportation and energy firms to voluntarily participate in monarch butterfly conservation by providing and maintaining habitat on potentially millions of acres of rights-of-way corridors on both public and private lands.
Both signed an integrated, nationwide candidate conservation agreement (CCA) and candidate conservation agreement (CCAA) for the monarch butterfly on energy and transportation lands throughout the lower 48 states.
The USFW noted that those formal yet voluntary agreements between the agency and both public and private landowners aim to conserve habitats that benefit at-risk species. It also “integrated” both CCA and CCAA programs so energy and transportation partners and private landowners can provide conservation seamlessly throughout their properties where there may be a mix of non-federal and federal lands.
The Washington State Department of Transportation recently wrapped up a roughly $13 million fish barrier correction project – resulting in a new 440-foot bridge that spans Kilisut Harbor along State Route 116. The new bridge not only improves safety for human travelers but also is, in the words WSDOT Project Engineer Dan McKernan, a “huge win” for local salmon and other fish species in the area.
[Photo courtesy of Washington State Department of Transportation.]
“The work involved replacing two small culverts that were installed in the 1950s. The channel here now with the bridge was not here previously,” he said, adding that the new channel aids in the annual migration of salmon in the area.
This work is part of WSDOT’s Fish Barrier Removal Program, which identifies and removes barriers to fish caused by culverts under state highways. The agency noted in a statement that it worked with the North Olympic Salmon Coalition or NOSC to complete this specific bridge project while also continuing to work with the Washington State Department of Fish and Wildlife to identify locations where culvert replacement will increase fish habitat.
“The area between Indian and Marrowstone Islands was historically comprised of tidal channels and salt marsh,” NOSC noted in separate statement. “Tidal waters exchanged freely between Oak Bay and Kilisut Harbor, flushing cold water, moving sediment, and allowing juvenile salmon to migrate northward from Oak Bay into the shallow, productive waters of Kilisut Harbor. The installation of the causeway in between Kilisut Harbor and Oak Bay eased transportation between the Islands, but choked the flow of water and sediment, eventually creating an artificial beach berm, a filled channel, and increased water temperatures in Kilisut Harbor.”
The construction of the new bridge also resulted in the removal that land barrier, reconnecting the large numbers of Hood Canal and Puget Sound out-migrating juvenile salmon that converge at Oak Bay with immense foraging opportunities available within Kilisut Harbor while also restoring and enhance important staging and foraging habitat for multiple coastal dependent and migratory birds. “Clean, cold water is now flowing north into Kilisut Harbor/Scow Bay,” the organization noted. “This mixing on each tide cycle is expected to improve water quality in Kilisut Harbor over time.”
The New York State Department of Transportation is helping expand a series of artificial reefs off the shores of Long Island as part of a three-year long multiagency effort. In September, the agency helped dump a retired tugboat, 16 rail cars, and a streel turbine on Hempstead Reef – the first of multiple “reef deployments” scheduled for 2020.
[Photo courtesy of New York State DOT.]
NY Governor Andrew Cuomo
In his 2020 State of the State address, Governor Andrew Cuomo (D) committed to doubling New York’s existing reef acreage by expanding seven of 12 existing sites and creating four new artificial reefs in Long Island Sound and the Atlantic Ocean – an expansion expected to be complete by 2022.
“[We are] proud to work with our sister agencies on this important program, repurposing transportation materials to expand artificial reefs and support biodiversity, fishing, and tourism,” explained Marie Therese Dominguez, NYSDOT’s commissioner, in a statement.
“It is another example of how [our state] is taking bold steps to protect our ecosystems and foster sustainable economic growth that will benefit current and future generations of New Yorkers,” she said.
The New York State Department of Environmental Conservation or DEC manages the state’s 12 artificial reefs, which include two reefs in Long Island Sound, two in the Great South Bay, and eight in the Atlantic Ocean. The 413-acre Atlantic Beach Reef is located three nautical miles south of Atlantic Beach with a depth of 55 to 64 feet. One of the first reefs created in New York, this reef was previously comprised of two vessels, nine barges, surplus armored vehicles, 404 auto bodies, 10 Good Humor trucks, steel crane and boom, rock, concrete slabs, pipes, culvert, decking, and rubble.
Moving forward, recycled materials from NYSDOT, New York Power Authority/Canal Corporation, and the Thruway Authority – among other public and private partners – are being put to new use to develop New York’s artificial reef sites.
The types of materials deployed onto the reefs from the NYSDOT over the last year include old concrete highway barriers, steel girders with concrete tops from the Staten Island Expressway, and 15 steel pipes from the old Kosciuszko Bridge; replaced by a new structure that opened in 2019.
Photo courtesy of New York State DOT
The DEC said those materials are then “strategically placed” to expand the reef, with the agency overseeing the cleaning of contaminants from recycled reef materials to mitigate potential impacts to sea life before being deployed to the reef sites. Once materials and vessels settle to the seafloor, larger fish – such as blackfish, black sea bass, cod, and summer flounder – move in to inhabit the new structures, and encrusting organisms such as barnacles, sponges, anemones, corals, and mussels cling to and cover the material. Over time, the recycled structures create a habitat mimicking that of a natural reef, DEC noted.
The U.S. population has reached 331 million people within nature’s boundary of 2.43 billion acres.
To transportation officials, those big numbers point to a density increase in many parts of the country ― with the ensuing encroachment into natural habitats creating higher chances for fatal motor vehicle crashes between humans and wildlife.
[Above photo from the Oregon DOT.]
However, in areas like Bend, OR, road improvements to U.S. Highway 97 that include a soon-to-be completed $1.2 million under-crossing are tamping down the frequency of such potential tragedies.
It is the third such under-crossing completed along that highway “and we’ve just finished the heavy lifting,” explained Peter Murphy, spokesman for the Oregon Department of Transportation – who added that previous agency projects “resulted in an at least 85 percent drop in crashes” along the four-mile stretch of Highway 97 that intersects the Gilchrist tourist area.
Highway 97, which lies about 25 miles from the peak of the Cascades, was once two lanes but will soon become a partially four-lane artery – equipped in certain sections with 100 feet of new median.
Murphy said the Oregon DOT has moved the dirt, set up the substructure, and poured the concrete for the roadway’s latest under-crossing. “Next comes vegetation removal and installation of a five-mile long ‘funnel’ fence, to channel the animals to the undercrossing,” he added. To the east, deer winter in spots where they find significant solar exposure; to the west, they forage in the slopes on young spring evergreen shoots and grasses.
“Highway 97 intersects their historic habitat, so there are collisions that hurt and kill people and wildlife, as well as damage property,” Murphy explained. “In the wild, thinning the population isn’t the only problem. Mother deer are lost so their fawns are orphaned and they wander aimlessly until they die.”
The progress on Highway 97 is being heralded because, while Oregon “is behind other states” in setting up wildlife access, according to Cidney Bowman, project manager for the Oregon DOT, the agency recently used research from places “like Banff (Alberta) and Montana and applied it to today’s design, which is visually appealing for large ungulates” to use under-crossings safely.
Bowman added that the proper fencing setup is “critical” to the effort, as did Zach Beget, the agency’s bridge designer for the project.
“To me, the biggest lesson learned was ensuring an early alignment was built for the wildlife path,” Beget said. “It was built for the height and width that we wanted. So, if we’re waiting for elk to pass, for instance, then we need a little more room.”
He added that the location of a crossing determines the most economical approach. “In a fill location, you can use the underpass; in a cut location, an overpass works,” Beget said.
Photo courtesy of Oregon DOT
The Oregon DOT is also installing gates so personnel will have easy access to inspect the bridge, “which will be valuable when moving equipment, as well as proper excavation below the bridge, to reach the desired height for animals,” he added. “We need to be aware of water elevations.”
Yet the overall process remains straightforward. “It’s not rocket science,” Bowman said. “We just need to make sure the animals will use the crossings by making them large enough and using the fence [which will cost an estimated $750,000] to guide them.”
Such projects cater to creatures not only great, but small, too.
For example, take the Inter-County Connector (ICC), which opened in 2011 in Maryland and includes an expansive wildlife mitigation “package.” A pre-construction survey indicated that the habitat along the 18.8-mile corridor held high concentrations of white-tailed deer; thus, it was built to include more than 40 bridges and culverts to provide safe passage for not only deer and small mammals, but also fish, reptiles and amphibians.
The Wyoming Department of Transportation built eight wildlife underpass structures spanning a 25-mile stretch of Route 89 at a cost of approximately $18 million, “with funding in place” for the next addition, said Scott Gamo, the agency’s environmental services program manager.
The Wyoming DOT is also completing the design of the Dry Piney Project, with in-house sponsorship as well as contributions from Wyoming Game and Fish Department and non-government organizations. “We hope it goes to bid process by this winter,” Gamo said, “with construction hopefully starting in early summer.”
Like Oregon DOT’s Murphy, Wyoming DOT’s Gamo said the results have been solid.
Construction of such under-crossings in Wyoming, he noted, resulted in an approximately 80 percent reduction in collisions. “That’s what we were hoping for” in a state with populations of approximately 400,000 Pronghorn antelope, 350,000 mule deer and 90,000 elk that cross along the state’s 6,700 miles of road, “much of which is through their habitat.”
Gamo added that the crossings “are becoming more common across the country,” noting similar projects in Colorado, Montana, Nevada, and Arizona “that have been very effective.”
Oregon DOT’s Murphy, too, said people in general “see that [building under-crossings] is a good thing and they step up to the table.” He added that there have also been other wildlife crossings in Oregon, “but most were for smaller critters. They typically are not built for bear, elk, and deer. What’s new is that our undercrossing was built for ungulates.” That only makes sense in a locale where wildlife is part of the attraction. “There is a great deal of wildlife in Oregon,” he said. “That’s one reason why people live in and visit our state.”
The key role birds, bees, and insects play in agricultural propagation is typically celebrated once a year during events such as Pollinator Week. But for many state departments of transportation, support for such “pollinators” is becoming a year-round endeavor.
Take Idaho, for one. Idaho has more than 11.8 million acres in agricultural production and many of the state’s leading crops rely on insect pollination. For that reason, the Idaho Transportation Department (ITD) is actively engaged in supporting ants, butterflies, beetles, and other wildlife responsible for helping pollinate flowering plants.
For starters, the ITD follows the Idaho Pollinator Protection Plan – recently published by the Idaho State Department of Agriculture – and partners with both it and the Idaho Department of Fish and Wildlife to put that plan into action.
One example of the ITD’s use of the plan’s guidelines can be found at the Interstate 84 Westbound Bliss Rest Area. A partnership between ITD, the Bureau of Land Management, the U.S. Fish and Wildlife Service, and Native Roots LLC resulted in the creation of a new “pollinator garden” located on the grounds of that rest area grounds.
Cathy Ford, ITD’s roadside vegetation coordinator and program manager, explained that native flowering plants – such as the cordroot beardtongue and the firecracker penstemon – were added to the garden along with native plants to fit the arid environment and provide pollinator habitat. “We hope to do another one on the eastbound side in the future,” she noted.
[Editor’s note: ITD is also a part of the Candidate Conservation Agreement with Assurances or CCAA for the Monarch Butterfly – a national agreement established in April and supported by the American Association of State Highway and Transportation Officials that encourages transportation and energy firms to voluntarily participate in Monarch Butterfly conservation.]
In addition to the Bliss Rest Area, ITD has several other ongoing projects to promote pollination wellness. ITD’s District 5 is working to install pollinator plantings around its office in Pocatello, which will include small-stature flowering shrubs and perennial flowers as well as some milkweed plants – the only food source for Monarch caterpillars – salvaged in April from a state irrigation ditch construction project. The focus at the District Office is to provide blooming plants from early spring through fall to best support pollinators, Ford noted.
Pollination “wellness” efforts also impact state DOT duties such as roadside and right-of-way moving practices. The Illinois Department of Transportation for one now uses “revised” mowing practices aimed at creating and maintaining habitat for pollinators, including the monarch butterfly. Last year, the Illinois DOT began following the Illinois Monarch Project Mowing Guidelines for Pollinators, establishing July 1 to August 15 as its “most extensive” roadside and highway right-of-way mowing period.
The agency said in a statement that by timing when mowing takes place and reducing the amount of land being mowed, the Illinois DOT is encouraging the growth of critical plant species, such as milkweed.
Back in Idaho, the ITD is also involved in the Operation Wildflower Program, where districts distribute native wildflowers to volunteer groups to seed in selected areas. Partnerships between ITD and Idaho Fish and Game led to the formation of “pollinator waystations,” created by seeding roadsides with native flowers and grasses. These efforts not only support more pollinators but also beautify Idaho’s roadways and reduce maintenance costs, Ford said.
“ITD uses a variety of native seed and pollinator plant species for re-vegetation activities on construction and maintenance projects around the state,” she added.
State departments of transportation may soon be forced to adapt to changing rules surrounding the protection of migratory birds within transportation construction projects.
As noted in part one of this story, a notice of proposed rulemaking originally issued January 30 by the U.S. Fish and Wildlife Service (FWS) – with a comment period set to end on July 20 – would change key aspects of the Migratory Bird Treaty Act of 1918 or MBTA in terms of how state DOTs manage migratory bird populations during transportation construction activities and would prevent them from being fined for accidentally killing birds such as geese, herons, ducks, and other migratory species.
Under the proposed rule change, many requirements would be considered voluntary and could result in many protective undertakings to be abandoned.
Photos courtesy Virginia DOT
One example centers on the Virginia Department of Transportation Hampton Roads Bridge-Tunnel expansion project. An estimated 25,000 seabirds recently lost their nesting site of 40 years when the entire South Island of the Bridge-Tunnel project was paved over during the tunnel expansion project. In early 2020. state DOT officials began work with researchers and federal agencies to establish alternative nesting areas, but those efforts were abandoned when the proposed rule loosened repercussions for bird deaths during construction and when federal money to protect or relocate the habitats elsewhere was eliminated.
As a result, Virginia’s Department of Game and Inland Fisheries submitted a request to the Army Corps of Engineers to use dredged material to build a new bird island to mitigate the situation and Governor Ralph Northam (D) acted in February to make sure this mitigation effort would occur. The Department of Game and Inland Fisheries plans to create a new habitat for the birds by preparing the artificial island adjacent to the Hampton Roads Bridge-Tunnel and will also seek authorization to put barges in place to provide additional nesting habitat in advance of the upcoming nesting season.
Furthermore, the Department of Game and Inland Fisheries has started developing a state regulation dealing with the “incidental take” of migratory birds; a step only California has emulated to date.
That illustrates the decisions state governments and state DOTs alike across the country may face in terms of protecting migratory birds during construction and inspection activities under the new FWS regulatory initiative.
The Migratory Bird Treaty Act of 1918 or MBTA – which guides the evaluation of bird nesting areas and flight paths in order to avoid “taking” of the creature’s lives unnecessarily – may change due to a notice of proposed rulemaking originally issued January 30 by the U.S. Fish and Wildlife Service (FWS), with its comment period set to end on July 20.
That proposed rulemaking would codify the Department of the Interior’s existing interpretation that MBTA only applies to actions “directed at” migratory birds, their nests, or their eggs and would not apply to any incidental killing of birds due to commercial activity.
This action may also change the way state of departments or transportation have traditionally dealt with migratory bird regulations and would also prevent them from being fined for accidentally killing birds such as geese, herons, ducks, and other migratory species.
Migratory birds are frequently killed by industrial construction activities and accidents such as oil spills or collisions with aircraft, such as the 2009 commercial jetliner crash-landing on the Hudson River after the plane collided with geese and lost all engine power.
Migratory birds also often make their homes in highway structures or nest in areas where construction is planned and as a result, over the past decade, the MBTA’s prohibitions have been an increasing target of litigation. In enforcing the MBTA, the federal government has typically relied on its discretion and FWS guidelines that recommend best practices for certain industries. State DOTs use those recommendations along with state-specific regulations to develop their own bird mitigation efforts where transportation construction is concerned.
Wikimedia Commons
However, under the current proposed rule, those efforts will become largely voluntary and could result in mitigation efforts being decreased in order to save on overall construction costs.
The move toward this proposed rule started on January 10, 2017 when a legal opinion – M-37041, Incidental Take Prohibited Under the Migratory Bird Treaty Act – interpreted the MBTA’s prohibitions and penalties as applying regardless of a violator’s intention. Under that interpretation, any act that takes or kills a migratory bird is within the scope of the MBTA prohibitions so long as the act resulted in the death of a bird.
That ruling’s conclusion is an otherwise lawful activity that results in an incidental take of a protected bird does not violate the MBTA. And it is that 2017 legal ruling that the FWS’s current proposed rule would codify as a way to provide state agencies and construction companies with “legal certainty” so that they would not be fined for incidental taking of migratory birds.
Conservationists have proposed a different direction, describing instead a migratory bird incidental take permitting system in the Migratory Bird Protection Act (H.R. 5552), or MBPA, introduced on January 8, 2020, with agreed-upon best management practices providing the basis for a permit.
The Federal Highway Administration uses a similar permit system in order to work with swallow populations in construction and inspection. The Section 1439 of the Fixing America’s Surface Transportation or FAST Act authorizes the temporary take of nesting swallows that is otherwise prohibited under the MBTA.
Under the FHWA’s permitting system, the entity undertaking a bridge construction project must submit a document that contains the practicable measures to minimize significant adverse effects on nesting swallows. But those measures can often be time consuming, costly, and include timing bridge construction activities to avoid bird nesting season as well as moving and restoring nesting areas that are near the work area or constructing temporary alternative nesting areas in the vicinity of the bridge.
How are state DOTs responding to such changes in migratory bird protection rules? We’ll examine that in part 2 of this story next week.
As the Texas Department of Transportation works its way through a three-year study to determine why bats make their homes in certain types roadway bridges and culverts, other states are engaging in similar bat-preservation endeavors as well – especially in terms of mitigating the impact of bridge demolition and construction activity on bat populations.
For example, the southern region of New Mexico is home to year-round bat activity and Jim Hirsch, District 4 environmental analyst with the New Mexico Department of Transportation, said bats commonly hang out under bridges that span perennial waterways, such as the Rio Grande and Pecos rivers.
Top photo by Diane Winterboer for the U.S. Dept. Of Agriculture/Washington State and Oregon DOTs; Above photo courtesy of Wikimedia Commons.
“However, they also [hang out] under bridges that span ephemeral waterways, especially those near irrigated agricultural fields,” he added. “Most bat species are not protected by federal or state law, but the New Mexico DOT recognizes their importance in the ecosystem and the benefits they provide to the agricultural industry.”
In addition, he said, New Mexico DOT “would rather manage bats with flexibility and adaptability, rather than by strict protocols and measures. It is in New Mexico DOT’s best interest to avoid listing of a bat species under the Endangered Species Act.”
Generally, Hirsch explained that the New Mexico DOT will install bat boxes under new bridges if the previous bridge supported daytime bat roosting activity. His agency will also perform bat exclusion measures if a bridge is scheduled for demolition or major rehabilitation during the “active season” for bat colonies.
“The active bat season usually coincides with the migratory bird nesting season in northern New Mexico,” he noted. “Therefore, avoidance and exclusion efforts usually protect both migratory birds and bats.”
A recent challenge faced by the agency is the cost of undertaking bat exclusion measure, as funds for such measures usually come from the limited resources of the New Mexico DOT’s environmental bureau budget. To change that, he said the department is evaluating cost effective partnerships with universities as well as with other state and federal agencies.
Research by the Texas DOT is creating a clearer picture of what specific types of bridge and culvert structures best buoy bat populations. The agency surveyed hundreds of bridges and culverts in West Texas over the last two years and found that state highway type pre-stressed concrete girder bridge designs situated near evergreen forests, deciduous forests, and standing water had a positive correlation to bat presence. Texas DOT also found that interstate highway and square box girder variables had a negative correlation on bat presence.
“These results corroborate and refine anecdotal observations from decades of Texas DOT work to attract and maintain healthy bat populations on bridges, including the placement of artificial roosts on bridges that are not the right type, but are in the right ecological setting,” noted Dr. Stirling Robertson, the biology team lead in Texas DOT’s natural resources management section.
He added that those variables differed between species of bats, which is allowing Texas DOT to target species-specific bridge design solutions.
With a better understanding of the variables attracting bats to bridges and culverts, as well as the demonstrable success of artificial roost design and placement, Texas DOT is looking for future success by applying this knowledge where appropriate across the state.
“Bridges that are in the appropriate ecological setting and that are being replaced or rehabilitated give us ideal opportunities to enhance or preserve bat colonies,” Robertson pointed out. “We can also retrofit existing structures with artificial roosts if the existing design is not bat friendly.”
