Minnesota Department of Transportation

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Research & Innovation

Detection and Characterization of Bumble Bee Nesting Habitat and Nesting Habitat Potential along Roadsides

Need Statement 703

Problem

Bumble bee (Bombus spp.) populations have seen declines throughout North America, with these declines attributed to habitat loss and degradation, pesticides, pathogens, climate change, and small population dynamics. The Rusty patched bumble bee (Bombus affinis; RPBB) is a bumble bee species that historically occurred throughout the Midwest and Eastern United States, from Maine to Minnesota and south through the Appalachian region. Declines of this species has been documented since the late 1990s, with the species currently occupying approximately 5% of its historical range. While RPBB was listed as an endangered species by the U.S. Fish and Wildlife Service in 2017, the species maintains a relative stronghold within Minnesota, particularly within the Twin Cities metropolitan region. This species is known to occur within MnDOT roadsides, and frequently requires federal Endangered Species Act consultation and mitigation. Current U.S. Fish and Wildlife Service (USFWS) guidance determines impacts (e.g., no effect; may affect, not likely to adversely affect; and may affect, likely to adversely affect) based on ground disturbance activities and extent in habitats (foraging, nesting, and overwintering) where RPBB are assumed to be present. RPBB nesting habitat impacts are restrictive to transportation projects, and adverse impacts to the species are assumed if ground disturbances within suitable RPBB nesting habitat exceeds 0.25 acre. However, RPBB nesting habitat and characteristics are poorly understood; less than 10 RPBB nests have been discovered range-wide, and nesting habitat characteristics are primarily based on other, surrogate bumble bee species. This knowledge gap may result in conservative nesting densities, habitat types, and assumptions, which may lead to excessive restrictions to transportation projects. Potential restrictions include staging area and ground disturbance limitations, project timing restrictions, compensatory mitigation requirements, and, in extreme cases, scheduling and project delivery implications due to entering into Formal Consultation with the USFWS.
This project proposes to further characterize and refine bumble bee nesting habitat by capturing and tracking wild, non-listed, surrogate bumble bee species back to nests using a novel experimental approach. Nest sites, if found, will be characterized to allow for comparisons to habitats present on MnDOT roadsides.

Objective

The purpose of this proposed project is to identify and refine bumble bee nesting habitat characteristics and compare these known characteristics with habitats present along Minnesota roadsides. Current knowledge gaps of endangered bumble bee nesting habitats have resulted in restrictive USFWS guidance, leading to restrictive ground disturbance thresholds for Minnesota Department of Transportation (MnDOT) projects. Benefits to MnDOT may include:

  • Reduction in regulatory constraints
  • Fewer restrictions on ground disturbance acreages
  • Fewer restrictions on ground disturbance timing
  • Streamlining Endangered Species Act (Section 7) consultation with USFWS
  • Avoidance of Formal Consultation with USFWS
  • Enhancing MnDOT project delivery

Previous research

Previous research tracking bumble bee movements have been completed and tracking techniques have generally fallen into two distinct categories: radio telemetry or tracking using conservation detection dogs. Radio tracking and telemetry is a relatively new technique that has been used to successfully track bumblebees determine habitat use, including nesting habitat. Transmitter size and weight has historically been a limiting factor when applied to small flying insects (e.g., impeding and influencing movements and behaviors) but advancements have led to smaller transmitters that do not have significant impacts to insect movements. Telemetry tracking study design varies but tracking can be accomplished within a site via fixed array, ground tracking, and even small planes.
Detection dogs have been used in environmental conservation applications, including detecting invasive species and biosecurity risks, and have demonstrated the ability to detect insects, including bumble bees (Bombus spp.). Scent amplifiers (e.g., essential oils and extracts) have been demonstrated to have minimal impacts to honeybees (Apis mellifera) in toxicity trials and may increase the probability of dogs detecting nesting bees treated with these scent amplifiers, as essential oils (e.g., wintergreen) are used by various entities (e.g., American Kennel Club and the Sporting Detection Dogs Association) for training, trials and events, demonstrating canine ability to detect these substances.
While tracking bumble bees using both radio telemetry and detection dogs have been successful, tracking methods for this study may be dependent on researcher experience and expertise, site characteristics, and other factors. Study sites will be selected during the proposal process, but generally it should be expected that the wild bee tracking will occur in areas known to harbor large populations of bumblebees and in areas beyond MnDOT rights-of-way (e.g., park district lands, U of M Arboretum, Minnesota Zoo, etc.). Sites used to characterize available roadside habitats may be used on MnDOT Trunk Highways, County State Aid Highways, and/or County Roads and will be chosen with an eye towards representative habitats and personnel safety.

Strategic priorities

Innovation & Future Needs

This project proposes to utilize a novel approach to bumble bee nest detection, and to characterize nest-site habitat to better understand the suitability of roadsides as bumble bee nesting habitat.

Asset Management

Roadside vegetation is an asset that helps protect road and other transportation infrastructure. In addition, roadside vegetation management is the responsibility of transportation agencies and recent regulatory changes associated with the listing of the rusty-patched bumble bee as endangered have reduced the ability of transportation agencies to maintain this asset. A better understanding of bumble bee habitat use, especially nesting habitat use, is expected to lessen the regulatory burdens currently faced for vegetation managers working in areas with this endangered species.

Climate Change & Environment

Understanding bumble bee nesting habitat characteristics could allow for more streamlined Endangered Species Act consultation with the U.S. Fish and Wildlife Service.

Expected outcomes

  • New or improved policy, rules, or regulations
  • New or improved business practices, procedure, or process

Expected benefits

Environmental Aspects: Other

Results of this study may allow for more streamlined Endangered Species Act consultation with the U.S. Fish and Wildlife Service.

MnDOT Policy: Change or inform a policy

Currently MnDOT has adopted an informal interim maintenance policy to avoid or minimize impacts to endangered bumble bees. This policy places a significant burden on the agency’s maintenance staff. Increased understanding of bumble bee habitat use is expected to create added flexibility for certain maintenance activities by targeting avoidance and minimization efforts on where they are needed most.

Operations and Maintenance

Currently MnDOT has adopted an informal interim maintenance policy to avoid or minimize impacts to endangered bumble bees. This policy places a significant burden on the agency’s maintenance staff. Increased understanding of bumble bee habitat use is expected to create added flexibility for certain maintenance activities by targeting avoidance and minimization efforts on where they are needed most.

Reduce Risk: Other

Better understanding of bumble bee nesting habitat use is expected to reduce regulatory risk. The federal Endangered Species Act allows for both civil and criminal remedies for non-compliance.

Technical advisory panel

Name and affiliation of individuals to consider for the Technical Advisory Panel.