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Bombus morrisoni 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Insecta Hymenoptera Apidae

Scientific Name: Bombus morrisoni
Species Authority: Cresson, 1878
Common Name(s):
English Morrison Bumble Bee
Taxonomic Source(s): Cresson, E.T. 1878. Descriptions of new species of North American bees. Proceedings of the Academy of natural Sciences of Philadelphia 1878: 181-221.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2bc ver 3.1
Year Published: 2014
Date Assessed: 2014-08-21
Assessor(s): Hatfield, R., Jepsen, S., Thorp, R., Richardson, L. & Colla, S.
Reviewer(s): Ascher, J., Jha, S., Williams, P., Lozier, J., Cannings, S., Inouye, D., Yanega, D., Woodard, H., Griswold, T. & Strange, J.
Contributor(s): Antweiler, G., Arduser, M., Ascher, J., Bartomeus, N., Beauchemin, A., Beckham, J., Cromartie, J., Day, L., Droege, S., Evans, E., Fiscus, D., Fraser, D., Gadallah, Z., Gall, L., Gardner, J., Gill, D., Golick, D., Heinrich, B., Hinds, P., Hines, H., Irwin, R., Jean, R., Klymko, J., Koch, J., MacPhail, V., Martineau, R., Martins, K., Matteson, K., McFarland, K., Milam, J., Moisan-DeSerres, J., Morrison, F., Ogden, J., Packer, L., Richardson, L., Savard, M., Scott, V., Scully, C., Sheffield, C., Sikes, D., Strange, J., Surrette, S., Thomas, C, Thompson, J., Veit, M., Wetherill, K., Williams, N., Williams, P., Winfree, R., Yanega, D. & Zahendra, S.
Facilitator/Compiler(s): Foltz Jordan, S., Hatfield, R., Colla, S. & MacPhail, V.
Justification:
This western North American species has declined in relative abundance by 82.57% over the past ten years, and persistence declines have also been high (>70%).  The EOO appears relatively stable, since most declines have been in the interior of the species' range.  Note that the Intermountain West, which is the heart of this species' range, is generally an under-sampled area. However, there are large areas within this region that appear to have been well-sampled in recent years with limited detection of this species, e.g., western Nevada and the Four Corners area (see attached map, from Hatfield et al. 2014). R. Thorp (pers. comm. 2014) notes the absence of this species in recent surveys at the well-surveyed Southwestern Research Station in Arizona. In other well-sampled areas of Utah, this species appears to be maintaining high numbers (J. Strange and T. Griswold pers comm. 2014). More research is needed to evaluate the status of this species throughout its range, especially eastern Oregon and Washington, and western Nevada. Overall, this species is uncommon, and appears to be declining in parts of its range (Williams et al. 2014, Hatfield et al. 2014). Although our analysis points towards a Red List status of Endangered for this species, we are recommending Vulnerable at this time, in light of the various uncertainties presented above (e.g. limited sampling in parts of the species' range; changes in habitats sampled in some areas; and apparent security of this species at a few known sites). 

 

Previously published Red List assessments:

Geographic Range [top]

Range Description:This species occurs throughout the Mountain West from California east of the Sierra-Cascade Ranges to southern British Columbia; in the Desert West especially in the highlands, and east to New Mexico, Texas, and north to western South Dakota (Williams et al. 2014). In addition, this species has been sporadically found west of the Sierra-Cascade crest in Oregon and California (Thorp pers. comm. 2014).

For a graph and map of relative abundance and range changes of this species over time, see the Supplementary Material.
For further information about this species, see 44937666_Bombus_morrisoni.pdf.
A PDF viewer such as Adobe Reader is required.
Countries occurrence:
Native:
Canada (British Columbia); United States (Arizona, California, Colorado, Idaho, Kansas, Nevada, New Mexico, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, Wyoming)
Additional data:
Continuing decline in extent of occurrence (EOO):Unknown
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:We evaluated this species’ spatial distribution over time using a measure of change in the extent of occurrence (EOO; see Figure 2 in the Supplementary Material) and a measure of change in persistence (analytical methods described in Hatfield et al. 2014). We also assessed changes in the species’ relative abundance (see Figure 1 in the Supplementary Material), which we consider to be an index of abundance relevant to the taxon, as specified by the IUCN Red List Categories and Criteria (IUCN 2012). For all three calculations we divided the database into historical (1805 – 2001, N=128,572) and current (2002-2012, N=74,682) records. This timeframe was chosen to meet the IUCN criteria stipulation that species decline must have been observed over the longer of three generations or 10 years. Average decline for this species was calculated by averaging the change in abundance, persistence, and EOO. This analysis yielded the following results (see also the Supplementary Material for a graph of relative abundance and map of change in EOO over time):
  • Current range size relative to historic range: 81.87%
  • Persistence in current range relative to historic occupancy: 27.49%
  • Current relative abundance relative to historic values: 17.43%
  • Average decline: 57.74%  
This species has declined in relative abundance by 57.74% over the past ten years, but its EOO has only declined by 18.13% over this time period, since most declines have been in the interior of the species' range. The relative abundance trend for the past 50 years also shows a strong downward trend; if the same rate of decline occurs, its relative abundance will be zero within the next 40 years. 

Note that the Intermountain West, which is the heart of this species' range, is generally an under-sampled area. However, there are large areas within this region that appear to have been well-sampled in recent years with limited detection of this species, e.g., western Nevada and the Four Corners area (see attached map, from Hatfield et al. 2014). R. Thorp (pers. comm. 2014) notes the absence of this species in recent collections at the well-surveyed Southwestern Research Station in Arizona.  In other well-sampled areas, this species appears to be maintaining high numbers; e.g., J. Strange and T. Griswold (pers. comm. 2014) note that B. morrisoni is the most abundant Bombus at Grand Staircase Escalante National Monument, southern Utah, and continues to be a fairly common species in pheromone traps in agricultural areas of northern Utah. Overall, this species is uncommon, and appears to be declining in parts of its range (Williams et al. 2014, Hatfield et al. 2014). More research is needed to evaluate the status of this species throughout its range, especially eastern Oregon and Washington, and western Nevada.

For a graph and map of relative abundance and range changes of this species over time, see the Supplementary Material.
For further information about this species, see 44937666_Bombus_morrisoni.pdf.
A PDF viewer such as Adobe Reader is required.
Current Population Trend:Decreasing
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:This species inhabits open dry scrub where it nests underground (Williams et al. 2014) as well as in structures and grass hummocks (J. Strange pers. comm. 2014). Example food plants include Asclepias, Astragalus, Chrysothamnus, Cirsium, Cleome, Ericameria, Helianthus, Melilotus, and Senecio. Males perch and chase moving objects in search of mates (Williams et al. 2014).

Bumble bees, as a whole, are eusocial insects that live in colonies composed of a queen, workers, and reproductives (males and new queens). Colonies are annual and only the new, mated queens overwinter. These queens emerge from hibernation in the early spring and immediately start foraging for pollen and nectar and begin to search for a nest site. Nests are often located underground in abandoned rodent nests, or above ground in tufts of grass, old bird nests, rock piles, or cavities in dead trees. Initially, the queen does all of the foraging and care for the colony until the first workers emerge and assist with these duties. Bumble bees collect both nectar and pollen of the plants that they pollinate. In general, bumble bees forage from a diversity of plants, although bumble bee species in a given area can vary greatly in their plant preferences, largely due to differences in tongue length. Bumble bees are well-known to engage in “buzz pollination,” a very effective foraging technique in which they sonicate the flowers to vibrate the pollen loose from the anthers.
Systems:Terrestrial
Generation Length (years):1

Use and Trade [top]

Use and Trade: There is no trade or commercialization of this taxon.

Threats [top]

Major Threat(s): No specific threats have been identified as impacting this species. Bumble bees, in general, are threatened by a number of factors including habitat loss, pesticide use, pathogens from managed pollinators, competition with non-native bees, and climate change (reviewed in Goulson 2010, Williams et al. 2009, Williams and Osborne 2009, Cameron et al. 2011, Fürst et al. 2014, Hatfield et al. 2012). Reduced genetic diversity resulting from any of these threats can be particularly concerning for bumble bees, since their method of sex-determination can be disrupted by inbreeding, and since genetic diversity already tends to be low in this group due to the colonial life cycle (i.e., even large numbers of bumble bees may represent only one or a few queens) (Goulson 2010, Hatfield et al. 2012, but see Cameron et al. 2011 and Lozier et al. 2011).

Conservation Actions [top]

Conservation Actions: Conservation needs:  Specific conservation needs for this species have not been identified. Due to the inherent vulnerability of many bumble bee species and importance of supporting wild bee populations for pollination services, the following general conservation practices are recommended: 
  1. Restore, create and preserve natural high-quality habitats to include suitable forage, nesting and overwintering sites. 
  2. Restrict pesticide use on or near suitable habitat, particularly while treated plants are in flower 
  3. Promote farming practices that increase of nitrogen-fixing fallow (legumes) and other pollinator-friendly plants along field margins.  
  4. Minimize exposure of wild bees to diseases transferred from managed bees. 
  5. Avoid honey bee introduction to high-quality native bee habitat.

Research needs:  Additional surveys for this species are needed in parts of its range, especially eastern Oregon and Washington, and western Nevada, where the species has not been detected in recent years (Hatfield et al. 2014). Research needs for North American bumble bees (as a whole) are summarized in Cameron et al. (2011), the final report for the 2010 North American Bumble Bee Species Conservation Planning Workshop.


Citation: Hatfield, R., Jepsen, S., Thorp, R., Richardson, L. & Colla, S. 2014. Bombus morrisoni. The IUCN Red List of Threatened Species 2014: e.T44937666A69004519. . Downloaded on 22 July 2017.
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