A number of states are adopting mowing practices along the edges of roads (the right of way) that are designed to allow diverse vegetation as habitat for butterflies and other animals. These practices have been supported by lobbying from conservation groups and are acceptable if they reduce the maintenance costs of right of ways. Is there evidence that reduced mowing results in greater abundance of butterflies?
A study in Winnipeg, Canada* addressed the question of whether butterfly diversity would increase or if it would be limited by the character of the management practices of surrounding urban landscapes. In the study the largest factor influencing butterfly populations was the diversity of plant species in the right of way area. Those right of ways with introduced plant species and had greater diversity and numbers of butterflies. The character of the surrounding urban landscape had little effect on butterfly populations and does not negate the benefits of conservation mowing. These results support the view that right of ways can be important wildlife habitat areas.
*Lionel Leston, Nicola Koper. Urban rights-of-way as extensive butterfly habitats: A case study from Winnipeg, Canada. Landscape and Urban Planning 157 (2017) 56–62