Source: The Conversation – Canada
Canada has more than a million kilometres of rural roads. Although vital corridors for travel and commerce, roads fragment habitats, disrupt animal movement and lead to millions of wildlife deaths from collisions.
Yet roadways shouldn’t be written off as ecological wastelands. Many jurisdictions mandate that a certain amount of land on either side of a road be maintained as a hazard-free “clear zone.” In the right-of-way area between the clear zone and the fence line, plants can grow, but tree encroachment has to be prevented and plants kept below a certain height for driver safety.
As it happens, these roadsides share some of the same characteristics as the natural open habitats, such as meadows and prairies, preferred by pollinators. Many species of bees, flower flies and butterflies tend to be most active in unforested areas, especially during the summer, when forests provide them with relatively few flowers to forage from.
This means that rights-of-way might be able to provide suitable habitat for pollinators — an especially desirable goal, given that habitat loss is a primary threat to pollinators worldwide.
However, controlling roadside plant growth typically involves spraying herbicides and mowing. These practices can harm pollinators: herbicides reduce the number and variety of plants, while mowing shears off flower stalks and can destroy nesting sites of bees that nest in plant stems.
Recent research I conducted with colleagues investigated the impacts of “low-intensity” roadside management on pollinators in two neighbouring counties near Ottawa. We captured and identified 3,773 bees and flower flies over two summers.
Low-intensity management involves mowing less often beyond the clear zone than the “business-as-usual” approach, as well as more targeted spot-spraying of invasive plant species instead of boom-spraying.
We found that low-intensity roadsides hosted around 45 per cent more pollinators, representing 23 per cent more species, than business-as-usual roadsides. The effect was strongest for bees, with one-third more species found along the low-intensity roadsides.
Benefits of low-intensity management
The neighbouring jurisdictions in our study use different practices for roadside maintenance. That meant we could identify the impact of low-intensity management while holding other aspects of the environment consistent.
Our results add to those of other studies conducted in Europe and the United States showing that reducing mowing and herbicide use can be good for pollinators.
This is true even when the plants that are allowed to grow and flower are non-native species (often dismissed as roadside weeds).
Non-native plants introduced to North America from Europe, such as sweet clover, chicory and birdsfoot trefoil, can still provide nectar and pollen for native North American pollinators such as bumble bees, solitary bees and hover flies.
Conserving pollinator-friendly habitats
In Canada, the total area of unpaved and vegetated roadside rights-of-way adds up to at least 10,000 square kilometres of land — an area about double the size of Prince Edward Island. This represents a substantial land area with potential to counteract some of the harmful impacts of roads.
However, there is an important danger in roadside habitats: pollinators could be killed by fast-moving vehicles on the roadway if they stray from the vegetated margins or try to cross to the other side.
In theory, more pollinator-friendly roadsides could be drawing pollinators into a death trap. Nevertheless, a detailed synthesis study concluded that the benefits of roadside enhancements for pollinators likely outweigh the costs.
This is a part of the reason why conservation groups like the Canadian Wildlife Federation have been working to transform roadsides and other rights-of-way throughout North America into functioning wildlife habitat.
To be sure, roadsides and other rights-of-way don’t provide habitat for all pollinator species, even when managed in a pollinator-friendly way. Canada is home to more than 900 species of bees and 500 species of flower flies, but we detected only 100 and 53 species, respectively, in our study.
Many bee species nest in dead wood, and many bees and other pollinators rely on woodlands for shelter and food. For example, flowering trees are a key pollen source for many bees in spring.
Safeguarding Canada’s natural habitat, including its forests, is essential for preserving a diverse pollinator community, not to mention other wildlife.
Nevertheless, our results show that roadsides shouldn’t be discounted as habitat. Simply managing them a bit less intensively can make a big difference for pollinators, while reducing costs at the same time.
This article was co-authored by Gil Miranda, a research technician at Agriculture and Agri-Food Canada, and Carolyn Callaghan, a senior conservation biologist at the Canadian Wildlife Federation.
Jessica Forrest receives funding from the Natural Sciences and Engineering Research Council of Canada.
Original source: https://analysis1.mil-osi.com/2026/10/22/making-small-changes-to-roadsides-can-help-pollinators/