[Pollinator] Bombus affinis - A 2020 Summary of Status

[Droege, Sam]

2020 Bombus affinis Summary

All

Below summarizes information collected from individuals interested in B. affinis this year.  Feel free to respond to the group on this email if you have additions corrections.

Summary:  No new populations outside of the Midwest / Middle Appalachia known core regions.  Populations appear down in Appalachia and up to neutral in the Midwest.

Results from Formerly Occupied parts of the Original Range

No surprises here.  Despite known surveys in ONT, PQ, ME, MA, CT, IN, OH, NC, MI - These areas have not had populations for years and that pattern continues.  Bumble bees low in New England - Drought may be a factor and late spring freezes in the MidAtlantic.

Appalachian Regional Populations

Virginia - 6 past sites visited, 3 with B. affinis and 3 without.  Primarily males in August.  No new sites discovered.   Low bumble bee numbers.  Late season high elevation freezes and cold weather may be a cause.  Lack of searching in woodland areas may be reason for low female numbers (relationship of woodlands to B. affinis numbers is worth investigating).

West Virginia - Similar weather issues to VA.  Despite extensive field work and many site visits, only 2 locations with the species.  One location had them previously recorded and, on the positive side, a new location was found in Greenbriar County, the southernmost known location of the species during the post-crash period.

Note, Appalachian populations, so far, are restricted to the relatively small area of the highlands bordering WV and VA.  No specimens found from the surrounding states despite those regions previously well within the original range.  These populations appear to be just barely hanging on.

MidWest Regional Populations

Wisconsin -  170 observations - 4 new counties coming from combined Citizen Science and DNR efforts.  Unclear how much of this good news is due simply to increased survey effort....comments from WI folks would be welcomed

Minnesota - Elaine Evans continues her repeated surveys of locations in Minneapolis (invaluable in assessing whether populations are actually increasing versus simply documenting presence in unsurveyed regions).  Mentions she had the best B. a. season since the late 90s!  (nice to have good news sometimes).  Unclear how surveys or records outside of Minneapolis went, anyone with information?

Iowa - Mixed messages about areas of increase and decrease, but populations are present with significant numbers of bees.

Illinois - I heard from no one, but online records indicated they are still present this year in far northern Illinois.

Back in October Rich Hatfield form Bumble Bee Watch mentioned that there were ~250 B. a. observations...all from the Upper Midwest traditional regions.  463 observation as of today in iNaturalist, again all from the Upper MIdwest a big increase from previous years.  Caveats on both in that effort/overlap was not assessed nor repeat observations of the same bee.

Note 3 nests found this year! - 2 in Minnesota and 1 in Wisconsin.  Does anyone have a description of the habitats of these nests and their outcome?

This is a summary of collected observations, good for giving people a sense of what is going on, but you can clearly see there is no coordinated survey for B. affinis or any bumble bees that crosses state / province boundaries.  And those state surveys, while valuable, are not yet in the position of telling us about statistically defensible trends in bumble bee populations.

More observations welcome.

sam


RETURN

A little too abstract, a little too wise,
It is time for us to kiss the earth again,
It is time to let the leaves rain from the skies,
Let the rich life run to the roots again.
I will go to the lovely Sur Rivers
And dip my arms in them up to the shoulders.
I will find my accounting where the alder leaf quivers
In the ocean wind over the river boulders.
I will touch things and things and no more thoughts,
That breed like mouthless May-flies darkening the sky,
The insect clouds that blind our passionate hawks
So that they cannot strike, hardly can fly.
Things are the hawk's food and noble is the mountain, Oh noble
Pico Blanco, steep sea-wave of marble.
         - Robinson Jeffers


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