Assessment Icon

                                                                                                                                                                     Toolbox Home

The selection of appropriate locations for pollinator habitat is important to protect pollinators from inputs such as pesticides and to maximize habitat benefits. Pollinators need food (pollen & nectar), nesting and clean water sources, so these are important components for site selection. As a general rule, the habitats most beneficial to local pollinators will be those that historically existed in that general area. This may mean treeless prairie habitat in some areas and tree and shrub planting in others. Below are some considerations for site selection, followed by habitat assessment guides for rural and urban landscapes and solar plantings that can be used to further guide decision-making about pollinator habitat locations or to assess the quality of pollinator habitat before and after projects are completed. The following are key considerations for selecting pollinator habitat projects:

key considerations for locating pollinator habitat projects

Site Assessment Forms

BWSR has developed assessment forms for rural and urban landscapes as well as solar habitat projects. The following are links to the assessment forms followed by guidance for the use of each assessment.

Urban and Rural Habitat Assessment Forms (pdf)

Project Planning Solar Habitat Assessment Form (pdf)

Established Projects Habitat Solar Assessment Form (pdf)

Rural and Urban Landscapes Assessment Form Guidance

The following summary provides information about the concepts and ideas behind each question in the habitat assessment forms for rural and urban landscapes. These assessments are intended to be used to determine if proposed project plans will likely lead to successful habitat or to assess projects after they are established.

Size of Project Providing Pollinator Habitat

Pollinator habitats must have room to provide adequate foraging and nesting spaces for pollinators.

Rural landscapes should have at least 0.5 acres of pollinator habitat, with a goal of at least 1.0 acre. Larger areas will likely provide greater flower and nesting opportunities.

Urban landscapes are often more limited in available space. While all sizes of pollinator habitats are beneficial in some way, there should be room for clusters of plants instead of single plants, room for nesting such as bare ground for ground nesting pollinators or logs/lumber with holes for cavity nesting bees, and a shallow clean water source.

Habitat Type

All types of habitats listed in the assessment form are beneficial to pollinators; however, the habitat type will determine what types of plants will be suitable for the project. If benefiting a particular type of pollinator or specific species of pollinator is a project goal, it is important to determine what types of habitat and plants that pollinator uses.

Cover Diversity

Pollinators prefer variety when searching for nectar or pollen. Bees, butterflies, moths, and birds are all drawn to different types, shapes, and colors of flowers. They use different plants for nesting and larval feeding. Planting a wide variety of plants helps ensure value for a wide range of pollinators that may visit the habitat.

Invasive plants reduce diversity and are generally visited by native pollinators less often, so are not counted towards species totals.

metro skyline

Seasons with Three Blooming Species Present

It is important that pollinators are able to find nectar from early spring through late fall. Pollinators are more likely to use a habitat that they can rely on throughout the growing season. See the plant selection part of this pollinator toolbox for the bloom seasons of different plant species.

Birdhouse

Habitat Connections

Many species of pollinators utilize different habitats for foraging and nesting. Being connected to another habitat increases their chances of survival. These connections are referred to as corridors.

Some species of pollinators can only travel very short distances at a time, sometimes less than a couple hundred feet. Sufficiently wide corridors play an important role in movement and migration of pollinators, especially smaller species. They help increase genetic diversity by connecting populations and support the re-establishment of populations of pollinators that have been reduced through habitat loss from development, disease, or events such as fire or flooding.

Available Habitat Components

Nesting and clean water sources are vital for pollinator health and development and include lakes, streams, rivers, ponds, and wetlands. Xerces Society provides information on different types of nesting sites that can be added and how to keep them maintained. Water can also be provided in residential landscapes through shallow containers with sloping sides that are kept clean by changing with fresh water (not through the use of chemicals or soaps). Adding rocks or gravel that rise above the water surface provide resting sites and reduce the risk of drowning.

Pesticide Risk

Pesticides used to control insects can drift into pollinator habitats during application, or move into the habitat through water sources. If surrounded by areas that use pesticides, pollinators are more at risk by moving through those areas to reach the habitat. Habitat locations should be a minimum of thirty feet from areas treated with pesticides.

Agricultural areas are not the only pesticide risk. Chemically treated lawns and gardens using pesticides or insecticides, especially those containing harmful neonicotinoids, should also be considered. Trees and tall vegetation can provide buffers from pesticide drift or run-off.

Likelihood of Meeting Pollinator Species Goals

Assess the likelihood of habitat to meet specific pollinator species goals. Consider if the habitat will provide the species specific nectar sources, pollen sources, larval food sources, nesting needs, and minimization of risks.

Expected Project Lifespan

Pollinators require reliable habitats. The investment of time and resources into creating the habitat will have the greatest return the longer it can be maintained. Some plants require two to three years to establish and all projects need long-term care to maintain pollinator benefits.

Score Significance

Look for areas where the habitat score can be improved. Changing the location or configuration of habitat might increase scores related to available acreage,  habitat connections, and pesticide risk. Adding additional plant species can increase values for diversity, seasons with blooming species present, and likelihood of meeting pollinator species goals. Low and medium quality habitats should look at ways to raise the quality of the habitat to a high or exceptional level.

 

Solar Project Habitat Assessment Form Guidance 

The following summary provides information about the concepts and ideas behind each question in the habitat assessment forms for solar projects. These assessments are intended to be used to determine if proposed project plans will likely lead to successful habitat.

Percent of Site Dominated by Wildflowers

Wildflowers should make up a high percentage of plantings to provide nectar and pollen sources. Native grasses are also important for pollinator nesting, with a goal of 40-50% native bunch grasses.

Percent of Site Dominated by Native Species Cover

Native vegetation species provide better quality food, pollen, and habitat sources than non-native species in most cases. Guidance and native options can be found in the Selecting Plants & Seed Mixes section of this toolbox.

 See “Note” at bottom of assessment for measurements of percent “cover”.

Cover Diversity (Number of plant species with >2% cover)

Pollinators benefit from plant diversity when searching for nectar or pollen. Bees, butterflies, moths, and birds are all drawn to different types, shapes, and colors of flowers. They use different plants for nesting and larval feeding. Planting a wide variety of plants helps ensure value for a wide range of pollinators that may visit the habitat.

Invasive plants reduce diversity and are generally visited by native pollinators less often, so are not counted towards species totals.

Seasons with at Least Three Blooming Species Present

It is important that pollinators are able to find nectar from early spring through late fall. Pollinators are more likely to use a habitat that they can rely on throughout the growing season.

Available Habitat Components Within One-Quarter Mile

Nesting and clean water sources are vital for pollinator health and development. While some pollinators travel long distances, many require nesting habitats to be near food and pollen sources.

Site Planning and Management (category only used for the Project Planning form)

A detailed management plan can includes measures that will ensure the sound function of solar equipment, prevent the invasion of non-native species and maintain vegetation diversity throughout the operational life of the facility, as well as other desired goals within the project. Having funding and a contract to implement are also part of this category to help ensure that the management plan will be implemented.

Signage that describes the area as pollinator friendly increases public awareness of the importance of pollinator habitats and how solar sites are helping to fulfill that need. Additional forms of outreach could include online information and press releases.

Seed Mixes (category only used for the Project Planning form)

A minimum seeds per square foot is set as 40 seeds to help ensure that a sufficient number of native plants will establish. Local sources of seed helps ensure that plants will be locally adapted and provide suitable habitat for local pollinator species. Including a sufficient percent of milkweed seed is also important as they are a larval host plant for Monarchs but also provide important habitat benefits for other pollinators.

Available Habitat Components On-Site (category only used for the Established Planting form)

Milkweeds provide the sole food supply for monarch butterfly caterpillars. Milkweed species should be selected from native options suitable to that region. Many native shrubs provide nesting habitat for pollinators, especially for those that do not travel long distances from nesting sites to feeding sites.

A detailed management plan can include measures that will ensure the sound function of solar equipment, prevent the invasion of non-native species, and maintain vegetation diversity throughout the operational life of the facility, as well as other desired goals within the project.

Signage that describes the area as pollinator friendly increases public awareness of the importance of pollinator habitats and how solar sites are helping to fulfill that need. Additional forms of outreach could include online information and press releases.

Insecticide Risk (% of project adjacent to insecticide use such as non-organic cropland, or on-site use)

Pesticides used to control insects can drift into pollinator habitats during application, or move into the habitat through water sources. If surrounded by areas that use insecticides, pollinators are more at risk by moving through those areas to reach the habitat. Habitat locations should be a minimum of thirty feet from areas treated with insecticides. See the fact sheet on Protecting Conservation Lands from Pesticides for additional information.

Agricultural areas are not the only pesticide risk. Chemically treated lawns and gardens using pesticides or insecticides, especially those containing harmful neonicotinoids, should also be considered. Trees and tall vegetation can provide buffers from pesticide drift or run-off.

Communication with surrounding landowners about the importance of protecting habitat from pesticide drift plays an important role in protecting pollinator populations that are using the project.

Score Significance

Scores above 85 are considered "exceptional habitat" while scores between 70 and 84 also meet pollinator standards. For scores that are lower look for areas where the habitat score can be improved. Low and medium quality habitats should look at ways to raise the quality of the habitat such as adding signage, planting milkweed as containerized plants or seeding in additional forbs to increase the percent cover of wildflowers. 

Solar Panel in Flowers

 

Contact

Dan Shaw
Senior Ecologist/Vegetation Specialist