SPECIES: Scientific [common] Bombus suckleyi [Suckley’s cuckoo bumble bee] Forest: Salmon-Challis National Forest Forest Reviewer: Mary Friberg Date of Review: 12/28/2017 Forest concurrence (or Yes recommendation if new) for inclusion of species on list of potential SCC: (Enter Yes or No) FOREST REVIEW RESULTS: 1. The Forest concurs or recommends the species for inclusion on the list of potential SCC: Yes__X_ No___ 2. Rationale for not concurring is based on (check all that apply): Species is not native to the plan area _______ Species is not known to occur in the plan area _______ Species persistence in the plan area is not of substantial concern _______ FOREST REVIEW INFORMATION: 1. Is the Species Native to the Plan Area? Yes_X__ No___ If no, provide explanation and stop assessment. 2. Is the Species Known to Occur within the Planning Area? Yes_X__ No___ If no, stop assessment. Table 1. All Known Occurrences, Years, and Frequency within the Planning Area Year Number of Location of Observations (USFS Source of Information Observed Individuals District, Town, River, Road Intersection, HUC etc.) 1960 10 Gibbonsville, ID (Lemhi County) The Global Biodiversity Information Facility Occurrence Download (October 2017) 1957 1 North Fork, ID (Lemhi County) The Global Biodiversity Information Facility Occurrence Download (October 2017) a. Are all Species Occurrences Only Accidental or Transient? Yes___ No_X__ If yes, document source for determination and stop assessment. b. For species with known occurrences on the Forest since 1990, based on the number of observations and/or year of last observation, can the species be presumed to be established or becoming established in the plan area? Yes___ No___ If no, provide explanation and stop assessment N/A – no occurrences have been documented since 1990 c. For species with known occurrences on the Forest predating 1990, does the weight of evidence suggest the species still occurs in the plan area? Yes_X__ No___ Provide explanation for determination Suckley’s cuckoo bumble bee is widely distributed on and around the Forest (see Map 1). The host species (the Western bumble bee) is still extant on the Forest (see Criterion 1), presumably at low densities. Parasitic species typically exist at lower abundances than their host species (see Criterion 4), and due to their life history are likely to be underrepresented in surveys (see Criterion 1), so it is possible that Suckley’s cuckoo bumble bee exists in low numbers on the Forest. If determination is no, stop assessment d. Map 1, Suckley’s cuckoo bumble bee range in Idaho (IDFG 2017a) IDFG (Idaho Department of Fish and Game). 2017. Suckley’s bumble bee (Bombus suckleyi). Internet website: https://idfg.idaho.gov/species/taxa/1475541. Accessed on October 23, 2017. e. Map 2, Suckley’s bumble bee occurrences on the Salmon-Challis National Forest (Idaho Fish and Wildlife Information System [January 2017]) 3. Is There Substantial Concern for the Species’ Capability to persist Over the Long-term in the Plan Area Based on Best Available Scientific Information? Table 2. Status summary based on existing conservation assessments Entity Status/Rank (include definition if Other) NatureServe G1G3- Critically imperiled/Vulnerable (At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very Global Rank steep declines, or other factors/At moderate risk of extinction due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors) NatureServe S2- Imperiled (At high risk of extinction due to a very restricted range, very few populations (often 20 or fewer), steep declines, State Rank or other factors) State List IDAPA- Arthropod Status SGCN- Tier 1 (Highest priority for the SWAP; represents species with the most critical conservation needs, i.e., an early-warning list of taxa that may be heading toward extirpation) USDA Forest Not Region 1 Sensitive Service Not Region 4 Sensitive USDI FWS No records found Other Not BLM Type 2 Not ranked by the Xerces Society Table 3. Status summary based on best available scientific information. Species (Scientific and Common Name): Bombus suckleyi [Suckley’s cuckoo bumble bee] Criteria Rank Rationale Literature Citations 1 A1 Suckley’s cuckoo bumble bee is known on the Forest from two historic The Global Biodiversity Information Distribution on occurrence records in the North Fork Ranger District (see Table 1). The Facility Occurrence Download Salmon-Challis most recent occurrence record is from 1960 (see Table 1). However, its (October 2017). National Forest host (the Western bumble bee) was sighted in 2017 near North Fork (see PSCC for Western bumble bee), which is also the location of one of the Thorp, R. W., D. S. Horning, and L. L. two historic records of Suckley’s cuckoo bumble bee. It is possible that Dunning. 1983. Bumble bees and host populations have remained stable in areas with historic records of cuckoo bumble bees of California Suckley’s cuckoo bumble bee (see Criterion 6). In addition, cuckoo (Hymenoptera: Apidae). Bulletin of bumble bees do not produce workers, so adults would only be the California Insect Survey: Vol. encountered above ground during host searching and mating flights 23. making surveys for Suckley’s cuckoo bumble bee challenging (Thorp, Horning, and Dunning 1983). Therefore, Suckley’s cuckoo bumble bee could still be extant on the Forest despite the lack of current occurrence records. Due to presumed declines in abundance of its host (see PSCC for Western bumble bee), the narrow range of recorded historical occurrences, and low dispersal ability (see Criterion 3), we predict that habitat is widely distributed but isolated and scarce across the Forest, increasing the potential of local extirpations (Rank A1). Confidence is low due to lack of recent occurrence data for Suckley’s cuckoo bumble bee and uncertainty of the current distribution and abundance of the Western bumble bee on the Forest. Confidence in Rank: High, Medium, or Low 2 C Suckley’s cuckoo bumble bee distribution is centered in western North Hatfield, R., Jepsen, S., Thorp, R., Distribution in America (Hatfield et al. 2015). Its historic range includes the Mountain Richardson, L. & Colla, S. surrounding West from northern California to Alaska, and extends east to New 2015. Bombus suckleyi. The IUCN geographic area Mexico, Colorado, and Dakotas (Hatfield et al. 2015). There is also a Red List of Threatened Species historic isolated population in the northeastern United States (Hatfield et 2015: e.T44937699A46440241. al. 2015). Current surveys indicate that Suckley’s cuckoo bumble bee is extant from Northern California to New Mexico, extending north to IDFG (Idaho Department of Fish portions of southern Alberta and British Columbia (Hatfield et al. 2015). and Game). 2017b. Idaho State Few occurrence records exist for Suckley’s cuckoo bumble bee in Idaho Wildlife Action Plan, 2015. Boise, (IDFG 2017b), but surveys conducted between 2002-2012 documented ID. occurrences in northern Idaho, Montana, and northwest Wyoming near the borders of Idaho and Montana (Hatfield et al. 2015). Based on surveys and historical records, the current range of Suckley’s cuckoo bumble bee (post-2002) encompasses only 43% of its historic range (Hatfield et al. 2015). Recent surveys indicate Suckley’s cuckoo bee has a wide distribution outside the Salmon-Challis National Forest (Rank C), although it is experiencing range contraction. Confidence in Rank: High, Medium, or Low 3 B Although nonparasitic bumble bee queens can disperse up to several Erler, S., and H. M. G. Lattorff. Dispersal kilometers while searching for nest sites, genetic studies of Bombus 2010. The degree of parasitism of Capability vestalis indicate that parasitic bumble bee queens do not disperse long the bumblebee (Bombus terrestris) distances (Erler and Lattorff 2010). Therefore, Suckley’s cuckoo bumble by cuckoo bumblebees (Bombus bee probably only disperses through suitable habitat (Rank B). (Psithyrus) vestalis). Insectes Confidence in this rank is low due to the lack of species-specific data on Sociaux: Vol. 57: No. 4. the specie’s dispersal capability. Species (Scientific and Common Name): Bombus suckleyi [Suckley’s cuckoo bumble bee] Criteria Rank Rationale Literature Citations Confidence in Rank: High, Medium, or Low 4 A There is no information for abundance or population density of Suckley’s Erler, S., and H. M. G. Lattorff. Abundance on the cuckoo bumble bee on the Forest (IDFG 2017b). Based on available 2010. The degree of parasitism of Salmon-Challis information, its host is probably uncommon on the Forest (see PSCC for the bumblebee (Bombus terrestris) National Forest Western bumble bee). Cuckoo bumble bees are typically more rare than by cuckoo bumblebees (Bombus their host species (Erler and Lattorff 2010). Rangewide, Suckley’s cuckoo (Psithyrus) vestalis). Insectes bumble bee has decreased in relative abundance by about 10% when Sociaux: Vol. 57: No. 4. comparing survey data from before and after 2002, and has been experiencing significant decreases in relative abundance in the past 50 Hatfield, R., Jepsen, S., Thorp, R., years (Hatfield et al. 2015). Richardson, L. & Colla, S. 2015. Bombus suckleyi. The IUCN Based on rangewide relative abundance trends and the estimated Red List of Threatened Species abundance of its host on the Forest, Suckley’s cuckoo bumble bee is 2015: e.T44937699A46440241. probably rare on the Forest (Rank A). Confidence is low due to lack of Forest-specific data on either Suckley’s cuckoo bumble bee or the Western bumble bee. IDFG (Idaho Department of Fish and Game). 2017b. Idaho State Confidence in Rank: High, Medium, or Low Wildlife Action Plan, 2015. Boise, ID. 5 A There is no Forest-specific information on population trends of Suckley’s Dolan, A. C., C. M. Delphia, K. M. Population Trend cuckoo bumble bee. Across its range, it is estimated that Suckley’s O’Neill, and M. A. Ivie.