In the summer, we are busy creating native landscapes, while in the winter we can take stock of what we have accomplished in the rest of the year. One way to do that is to look at how our gardens are influencing Chicago’s landscape as a whole. Since a major part of our mission is to provide habitat and resources for pollinators, here is a look at how Red Stem’s work accomplishes this.
In ecology, habitat connectivity is a measure of how easily an organism can move from one suitable habitat to another. In the case of pollinators, you can think of every garden or patch of flowers as an island of food and potential nesting sites. The closer these ‘islands’ are to each other, the easier it is for a bee or a moth to travel between them to collect food and bring it back to their nests. Illinois has almost 500 species of native bees, some the size of a pinhead and others almost the size of your thumb, and every one has a different kind of nest and specific types of flowers it prefers.
In general, the smallest bees, like the 2mm fairy bee (Perdita species) travel less than 200 yards from their nest, while the largest bumble bees (Bombus spp.)and carpenter bees (Xylocopa spp.) can go up to a mile. Practically speaking, if your neighbor two doors down also has a pollinator garden, a miniscule sweat bee can travel between your gardens, but not much farther. A medium size bee such as a leaf-cutter bee can travel a few blocks to the next patch of flowers, while a bumble bee or carpenter could commute to the neighboring ward, if there isn’t anything to eat closer.
For the purposes of estimating our company’s impact on the health of Chicago’s pollinator population, this map demonstrates connectivity between Red Stem’s gardens only. Looking at this map, we can see that Red Stem is creating gardens in a well-connected matrix of habitat “islands” for many bees!
Fortunately, the increasing popularity of native gardening, and the Park District’s growing body of pocket prairies and restored woodlands, these important insects have lots more to choose from than just our gardens.
Written by Liz Olney
Attracting Native Pollinators,Xerxes Society https://xerces.org/publications/books/attracting-native-pollinators