White-Nose Syndrome and increased disturbance of habitats used by bats for roosting and foraging has led to a growing concern about the U.S. bat population over the last decade. Bridge repair and replacement projects are required to follow additional regulatory requirements to avoid and minimize impacts to bats; when protected bat species are present on bridges. Some of these requirements (e.g.; timing restrictions) are challenging to implement given Minnesota's short construction season. The objective of this project was to evaluate the feasibility and efficacy of deploying non-lethal ultrasonic acoustic devices in the field to temporarily deter bats from roosting on bridges ahead of construction or maintenance activities; while minimizing harm to bats and non-target species. The technology was evaluated at two test sites in Minnesota; one short-term and one long-term; during the summer of 2019. Considering the findings from both the acoustic monitoring data and the field inspections; acoustic deterrents appeared to effectively work to temporarily deter bats from select abutments. This report presents the field study design; findings from the field implementation; research benefits; and implementation steps for the Minnesota Department of Transportation (MnDOT).
Several bumble bee species have declined dramatically; including the endangered rusty-patched bumble bee; Bombus affinis. Roadsides offer a unique opportunity to increase habitat for these declining species. The objectives of this study are to: (1) characterize the bumble bee community and floral availability within roadsides in the Minneapolis and Saint Paul; Minnesota; metro area; (2) estimate detection probabilities and occupancy for bumble bees using occupancy modeling; (3) determine the effort needed to detect rusty-patched bumble bees; and (4) examine the relationship of the bumble bee community to the surrounding landscape. We use rapid and broad-scale sampling at randomly selected locations. Despite overall low floral abundance; many bumble bee species; including rare and declining species; use roadsides. Occupancy models predict rusty-patched bumble bees occupy 4% of sites; with a 30% chance of detection if it is at the site. We recommend performing nine surveys in a single season to be 95% sure that B. affinis is detected if it is there. Bumble bee abundances and species numbers increase with more wooded area and floral cover. Crops are negatively associated with bee abundance; species numbers; and the presence of rare bumble bees. Our management recommendations for roadsides to support rare and declining bumble bees are: (1) incorporate additional bumble bee forage; (2) when weed control requires elimination of flowering plants; replace with bumble bee forage; (3) use our estimates for occupancy and abundance as a baseline to assess conservation efforts for bumble bees within roadsides in the metropolitan area of Minneapolis and Saint Paul.