Community engagement in urban habitat creation for the Rusty Patched Bumble Bee (Bombus affinis) indicates the potential of conservation in private yards

Abstract

Urban residential yards can provide flowering resources for pollinators, including the endangered Rusty Patched Bumble Bee (Bombus affinis). We created a participatory science project, the Evanston Host Plant Initiative (EHPI), to engage community members to inventory and grow host plants for Bombus affinis. In Evanston, Illinois, 275 people grew plants and uploaded photos of plants and bees to iNaturalist in 2021. We ground-truthed the iNaturalist data of Bombus affinis host plants submitted between 2012 and 2021 and determined that 96 % were still present. Our spatial analysis identified hotspots of host plants located outside residential lawns, at two public parks and a university campus. We found connectivity between host plants, considering the approximate 966 m (0.6 mi) foraging distance of Bombus affinis–a promising result for urban pollinator conservation, which would not have existed without host plants in private yards. Each host plant was within 966 m (0.6 mi) of another host plant, and most were within 483 m (0.3 mi). Between 2020 and 2021, iNaturalist observations of host plants increased by 116 % and bees by 143 %, indicating the potential for education to advance pollinator conservation efforts. We surveyed 155 people about their perceptions of yards as spaces for pollinator conservation, their yard management practices, and their experiences if they participated in the EHPI. The majority of respondents self-identified as enthusiastic gardeners and environmentalists who garden for pollinators, but almost all did not previously know about Bombus affinis, presenting opportunities for collective education and planting efforts for this species.