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3-1 Chapter 3 Imperiled Pollinator Profiles The Inland Northwest, which includes parts of Oregon, Washington, Idaho, and Nevada, is home to a diverse assemblage of pollinators (Figure 1-1). In this region, there is one candidate species for listing under the federal Endangered Species Act (ESA) as of March 2022. However, there are many imperiled pollinators in this region that are not protected by the ESA. This section provides profiles of ESA-listed and -candidate pollinator species found in the Inland Northwest, as well as imperiled pollinators that have the potential to be listed in the future based on NatureServe rankings and expert opinion (Table 3-1). The profiles of imperiled species not listed under the ESA include three imperiled bumble bees. This is not an exhaustive list of all declining pollinators in the region; the focus is on species in need of conservation that have a broad distribution and those that are more likely to affect Departments of Transportation (DOTs). An overview of the basic biology of bees, butterflies, and other insect pollinators can be found in Chapter 2. This section presents information on life history, distribution, threats, and habitat requirements for imperiled pollinators in this region. Information on known adult flight times (i.e., the breeding period) and larval active times (for butterflies and moths; larval bees live within nests) are included. The profiles also include a list of important plants that are used by each species as host plants or for pollen and/or nectar. Some of these plants are nonnative species or noxious weeds. These species are included in the profiles, as the information may be useful, but using them in revegetation efforts is not recommended (see Chapter 7 for more). Some basic conservation recommendations and information on the effects of roadside management on each species are also provided, when such information is available. Insects generally tend to be less well studied than vertebrates; therefore, very little is known about the biology and habitat requirements of some of these species. Other pollinator species may be better studied, but rigorous studies of the effects of different management practices on the species or their habitat may still be lacking. The best possible recommendations are made based on the available information. The profiles provide information on life cycles, host plants, habitat needs, and adult flight times that can be used to tailor maintenance and revegetation decisions (Chapters 6 and 7). General active times for adults and larvae are also provided. It should be noted that active times may shift regionally, such as with elevation or latitude, or from year to year with changes in climate. However, consultation with local experts, as well as biologists from state and federal agencies, is recommended to help DOTs develop meaningful management plans for species of interest in their areas because these profiles cannot capture the site- specific nuances that should be considered. As the profiles indicate, habitat loss is a primary driver of speciesâ declines. Roads can be a cause of habitat fragmentation (Box 5-3). However, with investments in high-quality revegetation (revegetation that prioritizes usage of native plants and high plant diversity, including an abundance of flowering plants that provide pollen and nectar or act as host plants for butterflies) where appropriate, roadsides can also provide an ideal opportunity to increase habitat connectivity for many species, including pollinators. It is important to note that although some of the species profiled in this chapter may be unlikely to use
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-2 roadside habitat for breeding, individuals may still use roadside habitat for nectar or pollen or as movement corridors. Therefore, it is worthwhile to invest in high-quality habitat restoration projects along roadsides near natural areas, preserves, and populations of imperiled species. Another common threat to many imperiled butterflies in the United States is noxious and invasive plants that displace required host plants. Here again, investing in high-quality habitat restoration using native plants can benefit imperiled pollinators, even if those pollinators are not using roadside habitat, by helping to slow the spread of invasive plants into key habitat areas. This section includes profiles of pollinator species that may not occur in roadside habitat, but may be found in other DOT land holdings, such as mitigation areas (Table 3-1). Table 3-1. List of profiled imperiled pollinator species in the Northern Plains region. ScientificÂ NameÂ CommonÂ NameÂ Status#Â ESAâListedÂ PollinatorÂ SpeciesÂ DanausÂ plexippusÂ MonarchÂ butterflyÂ CandidateÂ DecliningÂ PollinatorÂ SpeciesÂ BombusÂ morrisoniÂ MorrisonâsÂ bumbleÂ beeÂ G3Â BombusÂ occidentalis*Â WesternÂ bumbleÂ beeÂ G3Â BombusÂ suckleyi*Â SuckleyâsÂ cuckooÂ bumbleÂ beeÂ G2G3Â * SpeciesÂ underÂ reviewÂ orÂ areÂ onÂ theÂ U.S.Â FishÂ andÂ WildlifeÂ ServiceÂ workplanÂ toÂ beÂ evaluatedÂ forÂ listing underÂ theÂ ESAÂ asÂ ofÂ MarchÂ 2022. #Â StatusÂ ofÂ pollinatorsÂ isÂ eitherÂ theÂ ESAÂ statusÂ forÂ listedÂ speciesÂ orÂ isÂ takenÂ fromÂ NatureServeÂ (accessedÂ MarchÂ 2022)Â forÂ speciesÂ notÂ listedÂ underÂ theÂ ESA.Â Â ï· G1:Â CriticallyÂ Imperiled.Â AtÂ veryÂ highÂ riskÂ ofÂ extinctionÂ dueÂ toÂ extremeÂ rarityÂ (oftenÂ fiveÂ orÂ fewer populations),Â veryÂ steepÂ declines,Â orÂ otherÂ factors. ï· G2:Â Imperiled.Â AtÂ highÂ riskÂ ofÂ extinctionÂ dueÂ toÂ veryÂ restrictedÂ range,Â veryÂ fewÂ populationsÂ (oftenÂ 20Â or fewer),Â steepÂ declines,Â orÂ otherÂ factors. ï· G3:Â Vulnerable.Â AtÂ moderateÂ riskÂ ofÂ extinctionÂ dueÂ toÂ aÂ restrictedÂ range,Â relativelyÂ fewÂ populations (oftenÂ 80Â orÂ fewer),Â recentÂ andÂ widespreadÂ declines,Â orÂ otherÂ factors. ï· G4:Â ApparentlyÂ Secure.Â UncommonÂ butÂ notÂ rare;Â someÂ causeÂ forÂ longâtermÂ concernÂ dueÂ toÂ declinesÂ or otherÂ factors. ï· G5:Â Secure.Â Common;Â widespreadÂ andÂ abundant. ï· G#G#:Â RangeÂ Rank.Â AÂ numericÂ rangeÂ rankÂ (e.g.,Â G2G3)Â isÂ usedÂ toÂ indicateÂ theÂ rangeÂ ofÂ uncertaintyÂ in theÂ statusÂ ofÂ aÂ speciesÂ orÂ community. ï· T#:Â InfraspecificÂ TaxonÂ (forÂ subspeciesÂ orÂ varieties).Â TheÂ statusÂ ofÂ infraspecificÂ taxaÂ isÂ indicatedÂ byÂ aÂ âTâ rankâÂ followingÂ theÂ speciesâÂ globalÂ rank.Â ForÂ example,Â theÂ globalÂ rankÂ ofÂ aÂ criticallyÂ imperiled subspeciesÂ ofÂ anÂ otherwiseÂ widespreadÂ andÂ commonÂ speciesÂ wouldÂ beÂ G5T1.
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-3 3.1 MonarchÂ ButterflyÂ (DanausÂ plexippus)Â JanÂ FebÂ MarÂ AprilÂ MayÂ JuneÂ JulyÂ AugÂ SeptÂ OctÂ NovÂ DecÂ AdultÂ LarvaeÂ AdultÂ monarchÂ (topÂ left)Â andÂ monarchÂ distributionÂ withinÂ theÂ U.S.Â (topÂ right).Â AdultÂ flightÂ timesÂ (i.e.,Â breedingÂ period;Â blue)Â andÂ larvaeÂ activeÂ periodsÂ (green)Â forÂ monarchsÂ inÂ thisÂ regionÂ areÂ shownÂ inÂ theÂ chartÂ (bottom).Â AdultÂ andÂ larvalÂ activeÂ timesÂ varyÂ regionally;Â seeÂ FigureÂ 3â1Â forÂ regionallyÂ specificÂ suggestedÂ managementÂ windows.Â PhotoÂ credit:Â StephanieÂ McKnight/TheÂ XercesÂ Society.Â Order: Lepidoptera Family: Nymphalidae Status: Candidate Distribution: As of 150 years ago, the monarch was restricted to southern Canada, the lower 48 states, Mexico, Central America, and northwestern South America. In recent years the species has spread or been introduced to other areas including Spain, Hawaii, Australia, and New Zealand. Where it occurs: During the breeding season, monarchs can be found in terrestrial habitats throughout the western United States, but they tend to avoid dense forest. How to recognize: Orange and black monarchs are larger than most butterflies with similar coloration. In contrast to the species that most closely resembles monarchsâ viceroysâmonarchs lack the black line crossing the middle of each hind wing. Behaviorally, monarchs tend to glide more than most other butterfly species. Life cycle: Western monarchs generally breed west of the Rocky Mountains and overwinter along the Pacific coast. However, there is some mixing between the western and eastern populations (which breed east of the Rocky Mountains and overwinter in central Mexico), with some western monarchs migrating to central Mexico. Monarchs have several generations a year, which spread out and move north and west from the overwintering sites. Adults and larvae can be found in the West throughout the breeding season. In the Inland Northwest, monarch breeding season typically occurs from mid-May through the end of September (Figure 3-1). In the fall, adult monarchs enter reproductive diapause and return to overwintering sites along the California coast. Those individuals leave the overwintering grounds in MonarchÂ butterflyÂ larvaeÂ PhotoÂ Credit:Â RayÂ Moranz/TheÂ XercesÂ SocietyÂ
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-4 spring to lay eggs on milkweeds, the larval host plant. While larvae specialize on milkweed, adults use a variety of plants for nectar (Table 3-2). Habitat needs: Although monarchs tend to avoid dense forests, they use most terrestrial and wetland ecosystems for breeding and migration, as long as those ecosystems have milkweeds and nectar sources. This includes roadsides: monarchs lay eggs on a variety of milkweed species on roadsides and in roadside ditches. Top reasons for decline, if known: Loss and degradation of overwintering and breeding habitat;Â lossÂ of habitat via conversion to row-crop agriculture and urban development; use of herbicides that kill milkweeds and nectar sources; use of insecticides that kill monarchs or cause negative but sublethal effects. General conservation recommendations: Protect and restore breeding habitat in this region; this includes planting of native milkweed and nectar plants. The Snake River basin has been identified as an especially important part of this region for monarch conservation efforts. Reduced use of pesticides will benefit the conservation of this species. Roadside management recommendations: Mowing during the breeding season (mid-May through the end of September) will likely kill many monarch eggs, larvae and pupae. Spraying of herbicides may kill milkweed and nectar plants. Table 3-2. Plants used by western monarchs. SpeciesÂ NameÂ CommonÂ NameÂ NotesÂ LarvalÂ HostÂ PlantsÂ AsclepiasÂ cordifoliaÂ HeartleafÂ milkweedÂ LikesÂ rockyÂ soilsÂ AsclepiasÂ fascicularisÂ NarrowâleavedÂ milkweed AsclepiasÂ speciosaÂ ShowyÂ milkweed AsclepiasÂ cryptocerasÂ PallidÂ milkweed AsclepiasÂ incarnataÂ SwampÂ milkweed NectarÂ PlantsÂ CirsiumÂ occidentaleÂ CobwebbyÂ thistle CleomeÂ luteaÂ YellowÂ spiderflower EriogonumÂ umbellatumÂ SulphurâflowerÂ buckwheat EuthamiaÂ occidentalisÂ WesternÂ goldentop MonardellaÂ odoratissimaÂ MountainÂ monardella GaillardiaÂ aristataÂ Blanketflower RudbeckiaÂ occidentalisÂ WesternÂ coneflower SolidagoÂ spp.Â Goldenrod
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-5 TakenÂ fromÂ handoutÂ createdÂ byÂ MonarchÂ JointÂ VentureÂ andÂ TheÂ XercesÂ Society:Â https://monarchjointventure.org/images/uploads/documents/MowingForMonarchsUpdated.pdf.Â Figure 3-1. Management timing windows for monarchs in the United States. Roadside milkweed guides: ï· Milkweeds of ID, OR, and WA: https://xerces.org/publications/fact-sheets/roadside- habitat-for-monarchs-milkweeds-of-id-or-wa ï· Milkweeds of NV and UT: https://xerces.org/publications/fact-sheets/roadside- habitat-for-monarchs-milkweeds-of-nv-ut 3.1.1 References Dilts, T. E., M. O. Steele, J. D. Engler, E. M. Pelton, S. J. Jepsen, S. J. McKnight, A. R. Taylor, C. E. Fallon, S. H. Black, E. E. Cruz, D. R. Craver, and M. L. Forister. 2019. âHost Plants and Climate Structure Habitat Associations of the Western Monarch Butterfly.â Frontiers in Ecology and Evolution 7:188. Espeset, A. E., J. G. Harrison, A. M. Shapiro, C. C. Nice, J. H. Thorne, D. P. Waetjen, J. A. Fordyce, and M. L. Forister. 2016. âUnderstanding a migratory species in a changing world: climatic effects and demographic declines in the western monarch revealed by four decades of intensive monitoring.â Oecologia 181(3):819â830.
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-6 Pelton, E. M., C. B. Schultz, S. J. Jepsen, S. H. Black, and E. E. Crone. 2019. âWestern Monarch Population Plummets: Status, Probable Causes, and Recommended Conservation Actions.â Frontiers in Ecology and Evolution 7:258. Satterfield, D. A., F. X. Villablanca, J. C. Maerz, and S. Altizer. 2016. âMigratory monarchs wintering in California experience low infection risk compared to monarchs breeding year-round on non-native milkweed.â Integrative and Comparative Biology 56(2):343â 352. Schultz, C. B., L. M. Brown, E. Pelton, and E. E. Crone. 2017. âCitizen science monitoring demonstrates dramatic declines of monarch butterflies in western North America.â Biological Conservation 214:343â346. The Xerces Society. 2018. Managing for monarchs in the west: best management practices for conserving the monarch butterfly and its habitat. The Xerces Society for Invertebrate Conservation, Portland, OR. Available: www.xerces.org. Waterbury, B., A. Potter, and L. K. Svancara. 2019. âMonarch Butterfly Distribution and Breeding Ecology in Idaho and Washington.â Frontiers in Ecology and Evolution 7:172. 3.2 BumbleÂ Bees:Â MorrisonâsÂ BumbleÂ BeeÂ (BombusÂ morrisoni),Â WesternÂ BumbleÂ BeeÂ (B.Â occidentalis),Â SuckleyâsÂ CuckooÂ BumbleÂ BeeÂ (B.Â suckleyi)Â Order: Hymenoptera Family: Apidae Habitat Needs: Availability of food and nesting resources are key features in determining the success of a bumble bee colony. It is critical to maintain a bloom of floral resources throughout the spring, summer, and fall to supply bumble bees with a diversity and abundance of pollen and nectar, food for adults and larvae. Bumble bees nest above, on, or under the ground, utilizing pre-existing insulated cavities such as rock piles, areas of dense vegetation (e.g., bunch grasses), or old bird nests or mouse burrows. See Table 3-3 for a list of plants used by bumble bees. Top reasons for decline, if known: There are multiple factors affecting bumble bee decline including habitat loss, pesticide exposure, climate change, pathogens, and parasites, as well as the introduction of nonnative bee species. General conservation recommendations: Preserve, restore, and create high-quality habitat that includes suitable nesting, foraging, and overwintering sites throughout a speciesâ range. Assess and mitigate risk of pesticide use in or near suitable habitat to avoid treating flowers in bloom or contaminating nesting and overwintering sites. Avoid the introduction of managed honey bees and managed bumble bees to areas of natural habitat to protect and minimize disease exposure. Roadside management recommendations: Intensive mowing may deplete floral resources and potentially disturb species that have nested above ground in the roadside. Reduced mowing frequency would alleviate this problem. In areas with above-ground nesting species, avoid mowing during the nesting season to avoid harming nests. Use a diversity of plants in revegetation to ensure multiple species are in bloom from spring
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-7 through fall. Blanket spraying of herbicides can affect the health of bumble bees in the area by reducing floral resources. A recent study of roadside mortality of bumble bee queens in Sweden found that bumble bee queens used roadsides with both high plant diversity and low plant diversity in similar proportions when looking for nests. Queen mortality increased with traffic volume but was slightly lower along roadsides with higher quality vegetation. The authors recommend improving habitat quality along roadsides, and keeping a mown buffer strip next to the road to reduce queen mortality. 3.2.1 Morrisonâs Bumble Bee (Bombus morrisoni) Â JanÂ FebÂ MarÂ AprilÂ MayÂ JuneÂ JulyÂ AugÂ SeptÂ OctÂ NovÂ DecÂ AdultÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â AdultÂ MorrisonâsÂ bumbleÂ beeÂ (topÂ left)Â andÂ knownÂ stateâlevelÂ distributionÂ inÂ theÂ U.S.Â (topÂ right).Â AdultÂ flightÂ timesÂ (i.e.,Â breedingÂ period)Â areÂ shownÂ inÂ theÂ chartÂ (bottom).Â PhotoÂ credit:Â LeifÂ Richardson/TheÂ XercesÂ Society.Â Â Â Status: Vulnerable (G3) Distribution: Mountain and desert West Where it occurs: DryÂ shrubland Parasite of: In Alaska, likely parasite of Western bumble bee (B. occidentalis) and cryptic bumble bee (B. cryptarum). Flight Time: This species is typically active on the landscape from early May through mid October. Between November and April, queens are overwintering in the ground. Nesting behavior: NestsÂ underground. How to recognize: This bumble bee has black hair on the front of the face and yellow hair on the top of the head. The thorax is predominantly yellow, and black on the side. On the abdomen, segments one and two are yellow, segment three has some yellow, and segments four to six are black. Males may have different color patterns. Body size: Large. Queens range from 22 to 26 millimeters (0.87 to 1.02 inches) and workers range from 12 to 22 millimeters (0.47 to 0.87 inch).
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-8 3.2.2 Western Bumble Bee (Bombus occidentalis) Â JanÂ FebÂ MarÂ AprilÂ MayÂ JuneÂ JulyÂ AugÂ SeptÂ OctÂ NovÂ DecÂ AdultÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â AdultÂ westernÂ bumbleÂ beeÂ (topÂ left)Â andÂ knownÂ U.S.Â stateâlevelÂ distributionÂ (topÂ right).Â AdultÂ flightÂ timesÂ (i.e.,Â breedingÂ period)Â areÂ shownÂ inÂ theÂ chartÂ (bottom).Â PhotoÂ credit:Â RichÂ Hatfield.Â Â Â Status: Vulnerable (G3), under review; petitioned in 2018 to be listed as endangered under the California Endangered Species Act; petitioned in 2015 to be listed as endangered or threatened under the ESA Distribution: Western United States from the coast to mountain meadows out to the northwestern Great Plains. Population has shown sharp decline since the late 1990s west of the Sierra-Cascade ranges . Where it occurs: Urban, shrubland, grassland Flight Time: This species is typically active on the landscape from May through September). Between October and April, queens are overwintering in the ground. Nesting behavior: Usually nests underground. How to recognize: This bumble bee has mixed black and yellow hair on the face. The thorax has a yellow band in front of the wings and a black band or spot between the wings; behind the wings can be black, yellow, or mixed. Segment one of the abdomen is black, segments two and three are black or have some yellow, segments four and five are white or pale yellow, and segment six is black. Males may have different color patterns. Body size: Medium. Queens range from 20 to 21 millimeters (0.77 to 0.84 inch) and workers range from 9 to 15 millimeters (0.36 to 0.59 inch).
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-9 3.2.3 Suckleyâs Cuckoo Bumble Bee (Bombus suckleyi) Â JanÂ FebÂ MarÂ AprilÂ MayÂ JuneÂ JulyÂ AugÂ SeptÂ OctÂ NovÂ DecÂ AdultÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â AdultÂ SuckleyâsÂ cuckooÂ bumbleÂ beeÂ (topÂ left)Â andÂ knownÂ U.S.Â stateâlevelÂ distributionÂ (topÂ right).Â AdultÂ flightÂ timesÂ (i.e.,Â breedingÂ period)Â areÂ shownÂ inÂ theÂ chartÂ (bottom).Â PhotoÂ credit:Â CoryÂ Sheffield.Â Â Â Status: Imperiled to vulnerable (G2G3); under review for listing under the ESA Distribution: Mountain west and north into Canada Where it occurs: Forest, grassland, shrubland Parasite of: Western bumble bee (B. occidentalis) Flight Times: This species is typically active on the landscape in June and again in early to mid August. During the peak of summer, this species remains in the hostâs nest. Nesting behavior: Parasite of western bumble bee, which nests underground. How to recognize: This bumble bee has black hair on the face and a predominantly yellow thorax with a black stripe between the wings. The abdomen is predominantly black with a yellow band toward the posterior end interrupted medially. Males may have different color patterns. Body size: Medium. Females range from 18 to 23 millimeters (0.72 to 0.92 inch). Table 3-3. Plants used by bumble bees. SpeciesÂ NameÂ ByÂ BloomÂ PeriodÂ CommonÂ NameÂ NotesÂ Â EarlyÂ BalsamorhizaÂ sagittataÂ ArrowleafÂ balsamrootÂ Yellow;Â perennialÂ LupinusÂ polyphyllusÂ BigleafÂ lupineÂ Purple;Â perennialÂ
ChapterÂ 3.Â ImperiledÂ PollinatorÂ ProfilesÂ 3-10 SpeciesÂ NameÂ ByÂ BloomÂ PeriodÂ CommonÂ NameÂ NotesÂ Â PrunellaÂ vulgarisÂ ssp.Â lanceolataÂ LanceÂ selfhealÂ Purple;Â perennialÂ RosaÂ woodsiiÂ WesternÂ wildÂ rose/WoodâsÂ roseÂ Pink;Â perennialÂ MidÂ AsclepiasÂ speciosaÂ ShowyÂ milkweedÂ Pink;Â perennialÂ LupinusÂ argenteusÂ SilveryÂ lupineÂ White/blue/purple;Â perennialÂ MonardellaÂ odoratissimaÂ MountainÂ monardella/coyoteÂ mintÂ White/blue/purple;Â perennialÂ LateÂ AgastacheÂ urticifoliaÂ NettleÂ leafÂ horsemintÂ White/pink;Â perennialÂ ChamerionÂ angustifoliumÂ FireweedÂ Pink;Â perennialÂ SolidagoÂ canadensisÂ CanadaÂ goldenrodÂ Yellow;Â perennialÂ SymphyotrichumÂ eatoniiÂ EatonâsÂ asterÂ White/purple;Â perennialÂ 3.2.4 References DÃ¡niel-Ferreira, J., Ã . Berggren, R. Bommarco, J. Wissman, and E. Ãckinger. 2022. Bumblebee queen mortality along roads increase with traffic. Biological conservation 272:109643. Hatfield, R., S. Jepsen, E. Mader, S. H. Black, and M. Shepherd. 2012. Conserving bumble bees. Guidelines for Creating and Managing Habitat for America's Declining Pollinators. The Xerces Society for Invertebrate Conservation, Portland, OR. Williams, P. H., R. W. Thorp, L. L. Richardson, and S. R. Colla. 2014. Bumble Bees of North America: An Identification Guide. Princeton University Press, Princeton, NJ. doi:10.2307/j.ctt6wpzr9.