- November 20, 2017
Utility corridors run the gauntlet, traversing both the physical and the social landscape. Mile after mile and tower after tower, they distribute energy to cities and towns but also carve their path through the wilderness, disconnecting habitats and disturbing the environment. Sometimes this disturbance, from construction and maintenance, causes friction with nearby communities concerned with the wildlife residing there. With the proper management, however, these utility rights-of-way (ROWs) have the potential to connect natural landscapes and improve habitat conditions for certain wildlifeopen_in_new, while also carrying out their primary jobs of delivering utilities.
At Habitat Network, we look for opportunities to restore habitat value to the landscape. Places like yards and parks are excellent sites for providing wildlife habitat but even medians, cemeteries, and vacant lots, with the right plants and some thoughtful management, can be productive habitat. As urban and residential areas continue to grow, it will be increasingly important to incorporate native plants and sustainable designs into new infrastructure.
Utility rights-of-way total more than 157,000 miles of high voltage electric transmission lines covering over 11 million acresopen_in_new across the United States and wind through a myriad of land cover types and terrains. They are actively managed by utility companies. Their ubiquity and accessibility presents a valuable canvas for offering habitat features and resources for local wildlife. Implementing best management practices for birds and pollinators into power and gas line corridors can often meet the vegetation management goals of utility companies. The men and women who manage these expansive spaces are poised to become not just “maintainers” but “stewards” of these extensive landscapes.
Currently, federal law demands proper clearances on high voltage power lines and imposes strict penalties for noncomplianceopen_in_new. These regulations have resulted in an increase in transmission reliability but have also resulted in a more aggressive approach to vegetation management, reducing habitat availability and fragmenting the landscape. Often, vegetation is managed with indiscriminate mowing along and tree removal across wide swaths of the landscape. This type of vegetation management can sometimes raise alarms in nearby communities and create conflict among stakeholders.
Fortunately, the new word buzzing around utility lines is “stewardship”. What started as simply using less herbicides has led to erecting Osprey nest platforms and creating Karner Blue Butterfly meadowsopen_in_new within ROWs. This emerging focus on plant and animal biodiversity has started to shape a new paradigm of vegetation management geared towards wildlife habitat, soil conservation, and invasive species control, along with the appropriate line clearance.
As a result, many utility services have shifted towards a system of Integrated Vegetation Management (IVM)open_in_new in ROWs. IVM practices create planting zones across the utility corridor to prescribe vegetation solutions. The Wire Zone includes low growing plants like grasses and wildflowers, providing clearance and easy access. The Border Zone allows shrubs and small trees that block out taller species and beyond that bigger trees are allowed to remain. This diverse structure promotes dual goals of safe, reliable electric service with abundant, healthy vegetation across utility areas. IVM also provides the opportunity to introduce a wealth of ecological services.
Ecologists describe the value of connectivity in the landscape as an increase in the availability and accessibility of habitat resources across a track of terrain. Larger patches of habitat resources, or refuges, can be connected via smaller patches, called stepping stones. Greater connectivity can be achieved through longer corridors of similar habitat types and resources. Using a combination of IVM and best management practices for important bird or pollinator species, ROWs can be built and managed to recreate these corridors, providing habitat connectivity, line access, and long-term clearance with the diversity of vegetation and structure wildlife are attracted to.
Integrated Vegetation Management
The Golden-winged Warbler, federally listed as endangered, is, like many migratory songbirds, suffering from habitat loss. Its northern breeding range previously consisted of a mosaic of open shrublands amid mature woods. This landscape pattern was historically abundant as wildfires, storms, and beaver dams regularly opened up large spaces in mature forests which would fill in with shrubs and small trees.
As land around the Great Lakes became more developed, increases in agriculture opened up even more areas of shrubland and improved the habitat availability for Golden-winged Warblers. Eventually, however, as agriculture became less common, those farms grew into forests and our current management of wildlands has prevented the previous natural forces, like wildfires, to create new openings.
Audubon and other bird conservation groups have recognized the similarities between Golden-winged Warbler habitat requirements and utility rights-of-way vegetation goals and have catered some specific recommendations for vegetation managers in larger transmission corridors to improve the habitat value of these areas.
Bird and Pollinator Habitat
Start with structure, add native plants. Utility ROW vegetation requirements call for vegetation that does not impede the functioning of the utility service. Ideally, the vegetation should be easy to manage as well. Using the region’s local, native plant compositions for early successional and young forested habitats accomplishes this while also providing pollen and nectar, fruits and berries, nest sites for birds and solitary bees, and host plants for monarch caterpillars and other pollinatorsopen_in_new. Abundant selections of native plants provide the important resources wildlife need during the seasons they need them. Dense grasses and wildflowers can occupy the wire zone and can be managed with annual or biennial mowing in the late fall to control shrubs and small trees. The border zone can offer native fruit-producing shrubs and small trees, which provide winter resources and inhibit intrusion from larger trees.
Maintaining a young forest, or early successional habitat, in utility rights-of-way does require ongoing maintenance as shrubs and trees will eventually encroach on zones they are too tall for. This happens naturally as slow-growing, shade tolerant species make their way up through the grasses and shrubs, seeking more light and space. Invasive plant species can move in faster and more aggressively and will also need to be managed. Creating brush piles throughout ROWs–using the branches from cleared saplings and shrubbery–may be another excellent way to provide habitat resources for wildlife. Brush piles provide shelter for birds, small mammals, and reptiles. They attract food sources for owls and other raptors and can protect young, native seedlings from overbrowsing by herbivores. Place them out of the way where they will not need to be moved or worked around as wildlife make it their home.
Logs and Snags
Larger trees are strictly managed in ROWs to prevent damage to wires or towers in the event they fall over from old age or disease, or break in a storm. While this wood is usually removed from site, leaving the downed wood as logs within ROWs can provide a unique and important habitat feature for wildlife. Woodpeckers especially appreciate the beetle filled decay. Small mammals, reptiles, and amphibians will use downed wood for shelter, paths and runways, or as perches. Logs provide substrate for mushrooms and mosses to grow and eventually decompose, creating valuable soil resources to help sustain healthy vegetation.
Snags can be created by topping dead and dying trees to a height that is acceptable to power line clearance regulations but are still left standing tall enough to provide valuable habitat resources. A snag is full of bugs and larvae for hungry birds, offers perching places for raptors, and provides cavities that some nesting birds, like the Red-breasted Nuthatch above, require for successful nesting. Large snags created within the tree zone, along with a selection of deterrent strategies in high damage areas, may even help alleviate issues with woodpeckers excavating utility polesopen_in_new.
Beyond native vegetation, ROWs offer a unique opportunity to introduce a number of other valuable features for wildlife species suffering from a lack of suitable habitat. Bat houses, like those shown above, are easy to acquire or build and provide safe, healthy, and comfortable roosting places for bats when they are not hibernating. In the last decade, a deadly fungal disease, White-nose syndrome, has decimated some bat populations in the eastern U.S. but offering bat houses can provide energy conserving roosting places that may help bats recover from the fungal pathogenopen_in_new. Bats are great to have around as they provide millions of dollars worth of important ecosystem services like pollination and pest controlopen_in_new (each bat can eat thousands of flying insects per nightopen_in_new).
Coverboards, Hibernacula, and Bare Ground
Habitat for amphibians, reptiles, and small mammals can be created in ROWs by adding coverboards and hibernacula. These are places where small animals can safely shelter and moderate their temperatures on hot summer days or cold winter months. Coverboards can be wood or metal sheeting placed on the ground (they offer an excellent opportunity for viewing local wildlife to hikers and recreationalists who can carefully lift the sheet to see what is sheltering underneath).
Hibernacula can be made from rocks, mud and downed woody debris, to create an underground space for hibernating wildlife. The debris–rocks, logs, dirt, etc–from creating and maintaining utility ROWs can be used to build these features all along the corridor.
Many native bees require bare ground to build nesting cavities. Leaving open spaces, free of vegetation, offers this beneficial resource. Butterflies also require bare ground and will “puddle” in wet mud, sand, or gravel to collect essential minerals for mating and reproducing. And, several species of birds, like swallows and American Robins, use mud to build and secure their nests. Maintenance activities can result in opportunities to create bare ground habitat. Over time, these areas may fill in with vegetation but continuing management can keep enough of these habitat features within range.
Ecological Traps and Other considerations
As with homes, parks, and nature preserves, providing habitat and attracting wildlife comes with the responsibility of preventing the enhanced areas from becoming ecological traps, hazards, or sinks for the species being promoted. Mow timing, pesticide and herbicide application, tree pruning and invasive species management have seasonal timing concerns, like sensitive nesting periods, that can be mitigated by understanding key life cycles and habitat needs. Bat houses and nest boxes require regular maintenance to be safe, successful, and to prevent spread of disease; while some features, like snags and brush piles can be left behind, essentially gaining value with age. Other considerations could include adding flags or markers to power lines to reduce bird collisionsopen_in_new, or insulated perches for raptors to prevent electrocutionopen_in_new.
Public and Community Engagement
Recreation can connect individuals and communities with the outdoors and create a greater appreciation for nature, wildlife, and conservationopen_in_new. Utility ROWs offer a great opportunity for this as well. If you are interested in incorporating habitat for local wildlife into the management practices of an existing corridor or would like to provide input on a planned or scheduled ROW, get together a plan with the relevant information. What kinds of species are likely to be in the area and what are the plants associated with them? When are critical times of the year for those species’ reproduction and how could they be affected by current practices? Can recreation be a part of the plan for local engagement?
Communities often feel a strong attachment to the environment around them, either through recreation, conservation, or purely aesthetic reasons. Major anthropogenic disturbances to the environment, however, like utility corridors being cut through the nearby forest, can cause local uproar at town halls and other community assemblages. Utility companies can mitigate this response by developing a plan with local residence and conservation groups to incorporate wildlife habitat and sustainable practices into the vegetation management of the corridoropen_in_new. For example, utility foresters can advise on placement of habitat features, like bee houses and nest boxes, while community members take responsibility for their upkeep. The possibilities are as endless as the corridors themselves.