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Federal Register / Vol. 86, No. 161 / Tuesday, August 24, 2021 / Rules and Regulations
We agree that the Klamath-Siskiyou ecoregion, which hosts much of the historical range of the Franklins bumble bee, is very diverse and relatively rich in endemic species. The KlamathSiskiyou ecoregion is considered a global center of biodiversity, is an International Union for Conservation of Nature IUCN Area of Global Botanical Significance 1 of 7 in North America, and is proposed as a World Heritage Site and United Nations Educational, Scientific and Cultural Organization UNESCO Biosphere Reserve World Wildlife Fund 2020, entire. Extensive literature is available describing some of the biologic investigations in this ecoregion University of Oregon 2020, entire. However, we are not aware of any information linking Franklins bumble bee exclusively to endemic habitat features, including floral resources specific to this ecosystem.
2 Comment: One commenter noted that forage is only one component of Franklins bumble bees niche and does not alone define a habitat generalist, citing Devictor et al. 2010. They stated that even if the species is a general forager it could still have a relatively narrow habitat niche, adding that narrow pollen diets are associated with other rare bumble bees like Franklins bumble bee. They referenced a recent study, Wood et al. 2019, that looked at the diets of two species closely related to Franklins bumble bee, the American bumble bee and rusty patch bumble bee, and found these declining species had a narrow pollen diet, collecting around one-third fewer pollen types than other more stable species. The study further noted that these two species are shorttongued and the anatomical feature was mentioned as a potential factor in their narrower diet.
Our Response: There are many factors related to Franklins bumble bees and their habitat that we do not yet, and may never, understand; however, the information gathered for our assessment, including the opinion of the preeminent authority on the species Dr.
Robbin Thorp, indicates that Franklins bumble bee is likely a habitat generalist.
The commenter cites Devictor et al.
2010, when noting forage is only one component of Franklins bumble bees niche and may not alone define a habitat generalist. However, the same paper also states that a measure of ecological specialization is the assumption that specialists should cooccur with relatively few species; this is in contrast to generalist species who should co-occur with many different species across sites Devictor et al. 2010, p. 23, as has been observed with Franklins bumble bees.

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We agree that narrow pollen diets likely play a role in the decline of some Bombus species as the distribution and abundance of their floral resources change, but we do not have sufficient information to determine if this was a significant causal factor in the decline of the Franklins bumble bee. We do have some records of the species of plants visited by Franklins bumble bee, but we do not have an exhaustive or comprehensive list. Of the plants Franklins bumble bee is known to use, many are widely distributed. For example, California poppy is found in Oregon, Washington, Nevada, Arizona, Minnesota, and northwestern Baja California, Mexico. Nettle-leaf giant hyssop horse mint is native throughout western North America from British Columbia in Canada, to California to Colorado, where it grows in a wide variety of habitat types. Mountain monardella is found in montane forests between 600 m and 3,100 m 1,969 ft and 10,170 ft in elevation in Oregon, Washington, Nevada, and Utah.
Regarding tongue length, although the Franklins bumble bee is a shorttongued species, Wood et al. found no evidence of tongue length as a predictor of dietary breadth 2019, p. 9.
3 Comment: Several commenters disagreed that the present or threatened destruction, modification, or curtailment of habitat is not a threat to the Franklins bumble bee. One commenter stated that the Service analyzed fire suppression, agricultural intensification, urban development, livestock grazing, and effects of climate change, but only as to whether they contributed to the historical decline of Franklins bumble bee, not as current threats. One commenter stated that the climate change effects of increased drought severity, wildfire risk, and winter or early season flood risk are clear threats to Franklins bumble bee habitat in the current and near future;
they noted that flood risk is especially concerning for overwintering hibernating queens who may suffer mortality or respond by emerging too early for floral resources. The commenter also noted that due to the myriad of threats outlined in the August 13, 2019, proposed rule 84 FR 40006, it is incorrect to conclude that Franklins bumble bees habitat is unlimited in its capacity to provide uncontaminated resources to the species. One commenter stated that allterrain vehicle ATV use and herbicide use are current threats to Franklins bumble bees habitat, but provided no additional information upon which to base those claims.

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Our Response: In our analysis of the threats facing Franklins bumble bee in the SSA report, we completed a review of the best available scientific and commercial information on threats that have been present in the range of the bee Service 2018a, pp. 2340. During the public comment period on the proposed rule we did not receive any new information regarding potential threats that prompted us to change the conclusions in our analysis. The viability analysis takes into account the threats to the species that have influenced historical populations, threats that are influencing the current condition of populations, and threats which are likely to play a role in the species overall viability into the future.
In our SSA report for Franklins bumble bee, we noted those threats that are likely to play a role in the future pathogens, pesticides, and the synergistic effects of small population size, but did not complete a full future condition analysis; the dearth of information on this species, particularly the lack of species occurrence information after 2006, limited our ability to compare current and future condition.
Although empirical data are currently unavailable regarding the level of habitat loss and degradation specifically affecting the Franklins bumble bee, we do know that habitat impacts have caused the decline of other Bombus species e.g., Goulson et al. 2015, p. 2;
Goulson and Darvill 2008, pp. 193194;
Brown and Paxton 2009, pp. 411412.
Although habitat loss has had negative effects on Bombus species in general, available information did not indicate it was a driver of the decline of Franklins bumble bee. Habitat appears generally intact and in good condition throughout the known historical locations of the Franklins bumble bee and in all recent focused survey areas, and many of these habitats currently host a wide variety of other bumble bees, including closelyrelated species like the western bumble bee. As noted above in Summary of Biological Status and Threats, we have no information to suggest that any known Franklins bumble bee locations were in the path of wildfire at the time those locations were occupied. Further, as made evident in our geographic information system GIS analysis, most of the recent locations with confirmed Franklins bumble bee observations are on publicly owned land that is managed to preserve habitat conditions through a variety of mechanisms, including fire suppression. Furthermore, we have no information to suggest that habitat destruction or modification from fire
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