Global Status: G3G5
Global Status Last Reviewed: 26Jul2016
Global Status Last Changed: 26Jul2016
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G4 - Apparently Secure
Reasons: This was a very widespread bumblebee in eastern and central North America, but like three other North American species of its subgenus, it has suffered a severe decline during the past decade or less over most of its range. Unlike the others, it is still found regularly in and east of Vermont, and even increased in 2008 (over 2007 numbers) in Vermont and still occurs in the Great Smoky Mountains, but recent records elsewhere are few. If, as seems very likely, pathogen spillover (Otterstater and Thomson, 2008) is the main cause, very widespread extirpations or even extinction of this and other species of subgenus Bombus is plausible. Bombus terricola has declined drastically in most of its range since about 2003, but not as rapidly as B. affinis. Whether there has even been any decline from Alberta north and west id very unclear. At best B. terricola has declined severely in central postions of the range, and perhaps has begun to stabilize in the northeastern part, and might eventually recover more widely. At worst it may be on the way to extinction, but this now seems less likely than a few years ago. The trends over the next few years in Vermont, New Hampshire, Maine, the Maritimes, and Alberta north and westward should clarify the situation. This species was common over a large part of North America 10 years ago. Given the recentness of the decline occurrences mapped from 2002-2012 by Hatfield et al. (2014) may or may not represent still-extant populations. Hatfield et al. (2014) recommend vulnerable based on IUCN criteria. However it could prove to be endangered if most northeastern populations mapped as recent (2002-2012) fail to persist.
While so far this species has not declined as severely as three others of its subgenus, it is unknown whether any can be considered viable given current threats and the very recent overall history of the species. If populations are beginning to stabilize in and near New England, the species could recover back to secure (G4) status. It is unknown whether remaining northeastern populations are potentially viable, e.g. perhaps pathogen resistant, or whether they are doomed. If the decline of subgenus Bombus, is due primarily to impacts from Nosema which probably started in California (Evans et al., 2008), or perhaps near the commercial rearing facilities in Michigan and Ontario, it could be that distant regions like New England, the Maritimes, and northwestern Canada have not yet been fully impacted. However, the closely related B. affinis has not been found in Vermont or other northeastern states recently, while B. terricola has been, which suggests the latter is less impacted by whatever is causing the decline of the subgenus. See also the Xerces Society Red List of Pollinators, The Xerces Society website (http://www.xerces.org/yellow-banded-bumble-bee/) and the 2007 book by the Committee on the Status of Pollinators in North America. NatureServe's rank calculator version 3.1 as of August 2012 of GU and the assigned rank was revised to match that.
Nation: United States
National Status: NU
National Status: N5
U.S. & Canada State/Province Status
Alaska (SNR), Connecticut (SNR), Illinois (SX), Indiana (SH), Maine (SU), Maryland (SNR), Massachusetts (SNR), Michigan (SNR), Nebraska (SNR), New Hampshire (SNR), New York (S1), Pennsylvania (SNR), Vermont (S1S2), Wisconsin (S1)
Alberta (SNR), British Columbia (SNR), Labrador (SNR), Manitoba (SNR), New Brunswick (SNR), Newfoundland Island (SNR), Northwest Territories (SNR), Nova Scotia (SNR), Ontario (S5), Prince Edward Island (SNR), Quebec (SNR), Saskatchewan (SNR)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Special Concern
Comments on COSEWIC: Designated Special Concern in May 2015.
NatureServe Global Conservation Status Factors
Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: This mostly is a northern and Appalachian species, that does not widely into eastern arctic regions but does in a limited area of western Canada (Williams et al., 2012). Its historic range included southern Canada from Newfoundland and southern Labrador west through much of Ontario and close to half of Manitoba and Saskatchewan, reaching British Columbia and elsewhere in northwest Canada in and east of the gap area where neither population cluster of B. occidentalis occurred (Williams et al., 2012). In the U.S. it ranged in all of the border states form Maine to Montana and also in South Dakota and as recently as 1999-2002 in extreme northwestern Nebraska (Golig and Ellis, 2006). It ranged farther south in the east, including virtually all of New England and New York and much of Pennsylvania and it is even reported from Plummers Island, Maryland (Norden, 2008), and in the mountains as far as North Carolina and eastern Tennessee. Its current range is unknown, except that it still occurs fairly widely, but now uncommonly, in Vermont, New Hampshire, Maine and Nova Scotia as of 2007 or 2010 (Mt. Desert Island, Maine, fide Sam Droege), at one site in Pennsylvania in 2006 but it was not found there in 2007 (Evans et al, 2008; Richardson, 2008), and elsewhere in Pennsylvania (Centre Co.) in 2009 (fide Sarina Jepsen, Xerces Society). In Wisconsin the species was found in 2007-2008 mostly around the town of Mountain where it had been undetected since 2003, and in Ozaukee County, Wisconsin as of 2007 (Wisconsin Natural Heritage Inventory Program). It has been found at two locations in Tennessee since 2006 (Evans et. al., 2008). This species still has a substantial range in the Northeast, probably from Nova Scotia to Pennsylvania, but It is not certain whether other occurrences add up to a significant current range or just isolated remnants, although it does obviously still occur somewhat widely in the northeast corner of the range.
Area of Occupancy: Unknown 4-km2 grid cells
Area of Occupancy Comments:
Number of Occurrences: 21 to >300
Number of Occurrences Comments: See range extent comments. Originally tens of thousands at least, far fewer now (Evans et al., 2008) with only about 30 found in the past five years, but including more than 20 in Vermont as of 2008, when the species exhibited a sudden increase in abundance compared to 2007 (based on information from Leif Richardson, email to D. Schweitzer, December 17, 2008). See also Richardson (2008), who report it extant in seven towns in Vermont. There are presumably other populations scattered elsewhere at least in northern New England and adjacent Canada.
Number of Occurrences with Good Viability/Integrity: None to many (0-125)
Viability/Integrity Comments: There is no basis to consider any extant occurrence viable in the long term, or in most cases any basis to assume it is not. Since it is not known why the species is persisting in Vermont or whether there is any realistic chance that it will continue do so, it seems unlikley the Wisconsin occurrence would be viable given its isolation. There might very well be no viable occurrences or there could be dozens to hundreds in the extreme north of the range.
Overall Threat Impact: Medium
Overall Threat Impact Comments: Like other severely declining bumblebees, the main cause is thought to be pathogen spillover of an imported microsporidian (Nosema bombi) and an imported protozoan parasite (Crithidia bombi) from domesticated bumblebees (Bombus impatiens, B. occidentalis) that were reared in Europe and returned to the U.S for greenhouse pollination (e.g. Committee on Status of Pollinators, 2007, Colla and Packer, 2008, Evans et al., 2008) and references reviewed in all). While effects of the N. bombi are sub-lethal and sometimes quite mild for B. impatiens and some other bumblebees, impacts to subgenus Bombus appear to often be severe. The mite Locustacarum buckneri and the honeybee deformed wing virus may also be contributing to decline. There are probably other threats at least in some places such as land use changes and other forms of habitat loss, changes in nectar flora etc. A potentially serious threat might be novel pesticides, especially new persistent neonicotinoids (Colla and Packer, 2008), but more evidence is needed, and this seems inconsistent with findings that some bumblebee species are stable or increasing. The consensus seems to be that the above pathogens and parasites, perhaps especially an introduced Nosema strain, are probably the main causes of the very recent drastic decline. However, Sokolova et al. (2010) question this and suggest there may also be very closely related native North American Nosema and a less virulent native Nosema would be among the more plausible explanations for the high and moderate parasitism rates found by Koch (2011) among two species of subgenus Bombus in Alaska where both remain common. In a plausible worst case scenario some or all North American species of subgenus Bombus could be extinct within a decade or two, and one (B. franklini) may be already. Whatever the reason why the B. lucorum complex and B. occidentalis are persisting in Alaska and other far northern regions, its should be noted that B. terricola does not range nearly that far north. However, B. terricola so far is persisting widely at reduced levels in northern New England and probably far eastern Canada, and may be currently stable or increasing in that region, so it is possible threats are not as severe there, or perhaps one or more of the pathogens may not be fully established yet. Climate change is a threat in the mountains, where the species occurs mostly at higher elevations (above 1200 meters), and so could become restricted to higher elevations, and along the in southern edge of the range. On the other hand there is probably potential for this bee to expand farther north in Canada as the climate there warms.
Short-term Trend: Decline of <70% to Relatively Stable
Short-term Trend Comments: This species is severely declining in at least numbers in most, or all, of its range, and possibly is declining in range extent. Colla and Packer (2008) documented a significant decline and did not find it in southern Ontario, and Williams et al. (2009) assign it moderately high decline measure there. Evans et al. (2008) documented recent and concurrent declines elsewhere. Bombus terricola was the only one of 13 non-parasitic bumblebee species documented from the area 100 years earlier that Kearns and Oliveras (2009) did not find from 2001-2005 in the vicinity of Boulder, Colorado. The decline may be less severe in colder northeastern regions and at high elevations, based on a collections in Wisconsin, Vermont, New Hampshire, Maine, Nova Scotia, and Tennessee in 2007-2008 (Evans et al., 2008). Leif Richardson reports that there were over 20 documented occurrences in Vermont in 2008 (a short-term increase over previous recent years), where it has been seen occasionally from 2004-2007 as well. However, since about 2003 this species has declined overall, despite some apparent recovery in Vermont in 2004-2008 (Leif Richardson, email to D. Schweitzer, December 17, 2008). The overall recent trend has shown this species to be generally declining or crashing. It is worth noting that the closely related B. (B.) occidentalis also still occurs regularly in some places (e.g. Rao and Stephen, 2007). While they are declining significantly, these two species have clearly not crashed as severely as two close relatives B. (B.) affinis and B. (B.) franklini, and recent records suggest it has possibly stabilized or even recovered slightly in the far northeast of the range west to Vermont. However there is plenty of room for doubt that it has stabilized and Sam Droege reports that only one of this recently common species was found in a 2010 BioBlitz in Acadia National Park on the Maine coast.
Long-term Trend: Decline of 70-90%
Environmental Specificity: Broad. Generalist or community with all key requirements common.
Environmental Specificity Comments: This was a common generalized bumblebee in most of temperate eastern North America.
Other NatureServe Conservation Status Information
Inventory Needs: Needs to be looked for, especially in isolated places such as off-shore islands, and based on the few recent records, and also in the far northern or eastern parts of its historic range--especially New Hampshire, Maine and adjacent Quebec.
Biological Research Needs: Information on why this species is so far persisting in and east of Vermont could be extremely useful in the conservation of this species and subgenus. A first step needs to be continued monitoring.