- May 13, 2011
Where concrete meets the street, traffic circles hold unrealized potential for pollinators
There are 4 million miles of roads in the U.S., and 620,000 of them are municipal streets. Think of all the shrubs, trees, and flowers that could be lining those curbs! In addition to wildlife habitat, vegetated roadsides may also provide social and economic benefits to cities. Studies using videotapes to simulate differing levels of vegetation along roadsides suggests that parkway design and roadside vegetation can reduce fatigue, anger, aggression, fear, and stress among automobile drivers. Street-side or median gardens also promote tourism, making cities more enjoyable to walk, bike, and drive through. Walkable garden districts notoriously make for desirable living areas, enhancing character and property values of neighboring buildings. By slowing traffic somewhat, they may also encourage safer streets, for both people and birds.
Keep curb gardens wildlife-friendly with a few basic goals:
- Reduce mowing
- Encourage native plantings
- Choose hardy plants that can stand up to high traffic and pollution (think in terms of tolerance to compaction, drought, and salt)
- Keep diversity in mind– grasses, low shrubs, non-woody flowers
Choose plants to reduce safety concerns near roadways:
- Visibility is important. Keep curbside plantings low (max 3’3″)
- Nearest to the curb (within one foot) plants should be even lower (max one foot tall)
- Steer clear of manhole covers and fire hydrants
- Keep plants off the sidewalk and street – they could bother pedestrians, cyclists, and drivers
Roadsides pose a few special challenges for plants. These simple tips will help you maintain a healthy curb garden:
- Pavement stores heat that helps to create 24-hour hot, dry conditions for plants. Choosing drought-tolerant plants will reduce the amount of maintenance your garden needs
- Adding compost once or twice a year will feed the garden and suppress weeds
- Avoid pesticides; they have a high potential to leach into the sewer system, and will harm beneficial insects like bees
Brake for Birds
An estimated 60 million birds are killed in collisions with cars each year 1, and slower, more predictable traffic can help reduce these deaths. According to behavioral ecologist Pierre Legagneux, “As a car roars toward birds standing on the asphalt, they don’t check the driver’s exact speed when judging how soon to flap out of the way. Instead, the speed limit on the road, rather than the speed of the approaching vehicle, is a better predictor of how close a car gets before a bird startles into the air.” That means those smart birds know the average speed of cars traveling on whichever road they happen to be on and make judgments based on that understanding 2.
So how do birds sometimes end up as road kill? Some birds inadvertently fly in front of oncoming traffic while being pursued by a predator, or while pursuing prey. Still others are hit by cars that are speeding, making their speed limit prediction invalid. Obey the speed limit, and slow down whenever you see a bird crossing the road, in case there is another bird following behind it.
Roadside gardens can reduce the speed of traffic, giving birds and other wildlife more time to cross.
Hit The Road
“You road I enter upon and look around, I believe you are not all that is here; I believe that much unseen is also here.”Song of the Open Road -Walt Whitman
America’s roads can inspire you, as they did poet Walt Whitman, with their regional expressions of our biological heritage. Unfortunately, however, roadsides are increasingly losing ground to exotic invasive species that thrive in these frequently-mowed and disturbed stretches. A handful of imported “wildflowers” seen along roadways were much less common in Whitman’s time, such as chicory, purple loosestrife, and wooly mullein, to name a few. These plants—tolerant of full sun, low nutrients, and disturbance—were introduced to the United States both accidentally and intentionally. Moreover, their seeds move easily along our highway corridors.
Native plantings may require a little effort to establish at first (don’t be surprised when they spend their first year adding root mass underground), but hardy prairie perennials and grasses will do especially well in these environs. Working roadside means exposure to cars and people, so be sure to wear bright colors, garden in the daylight, and keep your tools, hoses, and other personal belongings out of harm’s way. For more help before you hit the road, be sure to see the the “Tips” section above.