In a study published this week, researchers from York University found that areas in Toronto with the most sidewalks, roads and concrete and the highest density of buildings had the fewest bicolonies.
The researchers, led by Prof. Amro Zayed from the Faculty of Science, together with Associate Professor Sheila Colla from the Faculty of Environment and Urban Change, set out to investigate how an urban environment can improve the health and abundance of pollinators, such as. Common eastern bumble bee.
“We used genetic techniques to fingerprint bumble bee workers and group them into families and nests, then we used triangulation by dividing the city into 270 lattice cells to determine where each nest is in Toronto and how far worker bees should go from their nest to forage. for food, ”Zayed said in a news release from York University on March 21.
Specifically, they looked at landscape, population demographics, and income in Toronto to determine which features improved habitat quality by noting which areas had the most nests and bees and the shortest distance to food. Feeding too far away can affect the life of the bumble bee workers and the condition of the colonies.
The researchers found that the foraging distance of bumble bees increased and the number of bees in each colony decreased in areas with a higher density of buildings, roads, paved surfaces, bare soil and humans.
But what surprised them, according to the news release, was that the relative density of houses within each lattice cell was associated with shorter foraging distances compared to areas of high density in multiple storey buildings.
“The type of urbanization seems to matter. If there are no urban parks or water forests, those urban areas with a higher density of single- or multi-family houses, which will typically have front and back gardens, seem to provide better foraging opportunities. for bumble bees, “said Colla.” It is increasingly important to design cities in a way that maintains and enhances biodiversity and ecosystem services. “
While urbanization had a clear negative effect on both colony density and foraging distance for worker bees, functional (non-cosmetic) green areas were generally associated with higher quality habitats for bumble bees.
In addition, the researchers found no evidence of a “luxury effect” – the idea that richer neighborhoods are better for bee habitats.
Zayed notes that there are several ways Toronto can become more friendly. The key, he says, is to create diverse green spaces.
“By transforming dull green spaces, such as lawns, into functional green spaces such as meadows and pollinating gardens, city dwellers can provide ideal habitats,” Zayed said. “Cities can also convert some of the concrete to green areas, but parks and forests are also beneficial to pollinators.”
Bumblebees like a variety of plant species, many of which can be easily planted in front gardens and backyards, including black-eyed Susan, Canadian golden rice, New England aster, purple sun hat, willow and various fruit trees and shrubs. These are also good for other pollinators.
The study advised that cities can also seek pollinator-friendly certifications through programs like Bee City – beecitycanada.org – by committing to implement measures aimed at protecting pollinators.
The paper – “Bees in the six: Determinants of bumblebee habitat quality in urban landscapes” – was published this week in the journal Ecology and Evolution.