Managing Roadsides For Pollinators
Excerpted from: Roadsides and Pollinators
Roads have the potential to fragment habitat, separating plants and animals from one another, as
well as to destroy habitat and increase invasive plant species, pollution, and erosion. New roads,
especially those through natural areas, can have adverse effects on the wildlife around them.
However, roadside vegetation can help to mitigate some of the negative impacts of roads. The
management of vegetation along existing roads can increase habitat diversity and provide
connectivity to habitat fragments in agricultural and urban landscapes.
Roadsides provide pollinators with food, breeding, nesting opportunities, as well as connectivity to
other habitat. Pollinator diversity can be high in roadsides, with bee and butterfly communities that
include both common and rare species.
Roadsides in the U.S. cover more that 10 million acres of land.
Managing roadsides for bees and butterflies will create highquality habitat for wildlie of all types.
Pollinator habitat along roadsides supports the pollination needs of adjacent farms and natural
Pollinators are critical to our food supply as well as to the health of ecosystems. Wild pollinators
such as the monarch butterfly and a number of bumble bee species are in decline, and beekeepers
in the U.S. have reported significant losses of managed honey bee colonies.
Pollinator declines are attributed to loss of habitat, pesticide exposure, diseases, parasites, and
effects of introduced species. Roadsides can benefit pollinators by providing foraging habitat,
places to breed, nest, and overwinter, and may act as corridors, linking patches of fragmented
Roadsides managed with pollinators in mind can achieve multiple goals of stabilizing roadsides,
reducing storm water pollution, supporting wildlife, and building public exposure and appreciation
for the local landscape.
The number of honey bee colonies has been in decline over the past half-century because of disease,
parasites, lack of floral resources, insecticides, and other factors. Since 2006, beekeepers have
experienced record high annual hive losses of 29% or more. Less is known about the
status of most of Wisconsin's pollinators, the data does exist suggests that numerous species are
experiencing declines similar to or more severe than the declines seen in honey bees.
Monarch butterflies in North America are vulnerable to extinction — Monarch butterfly populations have
dropped by 90% east of the Rocky Mountains. Three factors appear most important to explain the decline of
eastern Monarchs: loss of milkweed breeding habitat due to increased use of herbicides on genetically modified herbicide-resistant cropland and land conversion, logging at overwintering sites, and an increase in extreme weather events
Loss of milkweed breeding habitat due to increased use of herbicides.
Logging at overwintering sites.
An increase in extreme weather events.
Other butterfly species have also seen significant declines. Of the 800 butterfly species in the U.S., 17% are at risk
of extinction. Twenty-six species of butterflies are listed as threatened or endangered under the Federal Endangered
Concerns about pollinator decline and its repercussions have led to increased efforts to reduce threats
to pollinators. Managing existing habitat for pollinators and restoring additional habitat has been demonstrated
to increase pollinator abundance and diversity. Roadsides are a conservation opportunity to increase pollinator
Flowering plants in roadsides are important sources of nectar and pollen for pollinators that reside within
the roadside habitat as well as those that use the roadside as a partial habitat and reproduce or overwinter
elsewhere. Roadsides have the potential to provide resources needed for all life stages: host plants, nectar
plants, and overwintering habitat for butterflies.
Roadsides can also provide food for managed honey bees. Honey bee colonies require diverse sources of
pollen and nectar, and a lack of forage is frequently cited as a primary contributing factor to declines in honey
Roadsides can also provide shelter, sites for nesting or egg-laying, or overwintering habitat. Bees provide for
their young by constructing nests in which their offspring develop. Many ground-nesting bees prefer to nest
in sunny, bare patches of soil. Such patches can be found around the bases of native bunch grasses such
as little bluestem that tend to grow in dense bundles, leaving small areas of bare ground exposed between plants.
Roadside vegetation can also provide habitat for tunnel-nesting bees, which nest in hollow or pithy stems or
other small cavities. Bumble bees require a small, insulated cavity, such as underneath grass clumps or under
the thatch of bunch grasses.
For more information of native bee nesting: Native Bee Nesting
Landscape connectivity is important for the populations of many species, but due to urbanization, agricultural
intensification, and other human activities, habitat is becoming increasingly fragmented. Roadsides extend
across a variety of landscapes, often contain greater plant diversity than adjacent lands, and are generally
excluded from further development and major disturbances. In developed landscapes, such as intensively
managed agricultural lands, roadsides may provide areas of refuge for pollinators in an otherwise inhospitable
environment. The linear shape and connectivity of roadsides may help pollinators move through the landscape,
either for daily foraging or for dispersal to larger habitat patches
Tell WI-DOT To Support Pollinators
Ask the Wisconsin Dept of Transportation to replace the planting of non-native grasses
with pollinator-friendly native plants along Wisconsin roadways. Provide a corridor for
Bees, Butterflies and Birds to move through the State and restore the natural beauty of
Find Out More
The primary goals of roadside management by the Wisconsin Department of Transportation (WI-DOT) are motorist
safety, noxious weed prevention and soil stabilization. In recent years WI-DOT have also incorporated in a few
projects the incorporation of native grasses and wildflowers into rights-of-way to achieve this objective.
Integrated roadside vegatation management can combine the planting of native vegetation with site-appropriate
strategies to achieve cost-effective and more environmentally sustainable management of roadsides. As an
alternative to intensive mowing and blanket pesticide spraying of roadsides, vegetative management offers
Native grasses and flowers that are best adapted to local conditions and are able to tolerate drought
An established diverse plant community provides the most stable cover for reducing soil erosion
and keeping out seed.
Native plants offer improved weed and soil erosion control, reducing the need to mow or to spray
herbicides, which also reduces the costs.
Native plants are less likely to encroach on land bordering rights-of-way, a common complaint
Native plant communities will reduce runoff in the spring and act a snow fences in the winter,
trapping and preventing slow from blowing across roads.
Native plantings are aesthetically pleasing.
Native plantings may offer education opportunities, as they demonstrate how the wilder landscape
Native plant communities support more native wildlife than non-native plant communities.
For more information, read about roadside best managment practices that benefit pollinators: Handbook For Supporting Pollinators Through Roadside Managmeent
For the WI-DOT, the biggest concern about native plants which are much taller, is that it will increase the
number of accidents involving deer. Although there are no specific studies on this concern, other
research indicates that the presence of tall vegetation does NOT increase the number of deer-related collisions.
Because deer preferentially eat tender new growth of vegetation, allow native plants to grow without
frequent mowing should encourage fewer deer to browse along roadsides.
Native grass and wildflower seed does cost more per acre than the typically-used non-native grass
seed. One way to reduce this cost is to harvest sees from established stands of grasses or wildflowers.
Limited amounts of seed can be harvested by hand or sometimes through the use of farming
equipment. An advantage of harvesting see locally is that the local ecotypes are particularly well-suited
to the area.
Roadsides planted with native grasses and forbs should, after establishment, have less erosion as well
as a reduced need for mowing and for spraying herbicides.
Reduced storm water flow and reduced blowing snow due to native plantings may reduce costs.
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