Rusty-patched bumble bee nectaring on monarda.
Nature Notes for July 27, 2012
What an opportunity! Sheila Colla was coming to the
Alderville Black Oak Savanna to look for bumble bees. She spoke to Willow BeachField Naturalists a couple of years ago, but this was a chance to go into the
field with her and learn about her specialty.
I must admit that I had not given much thought to bumble bees
prior to Colla’s presentation. From this talk, I learned that many of the 50
bumblebee species that occur in North America are in decline. She was
introduced to the topic during her B.Sc. studies at University of Toronto. She
is now a Ph.D. candidate at York University and an acknowledged authority on
bumble bees.
In particular, the Rusty-patched bumble bee has gone from
quite common to a species at risk. In the 1970s, this species accounted for 14%
of the bumble bees in a thorough study of them in the Toronto area. From 2005
to 2008, Colla searched all the previously known sites and turned up only a
single Rusty-patched bumble bee in Pinery Provincial Park. A survey of Pinery
in 2009 turned up three individuals. The range of this species previously
extended from Maine to Georgia, north to southern Ontario and Quebec and west
to Minnesota.
Colla is trying to determine the extent of the decline of
all eastern North American bumble bees and determine some of the reasons for
these declines. Among these causes, she suggests climate change, habitat loss,
pesticides and/or disease. All of these things may be contributing, but so far,
no one really knows why the bees are disappearing.
She is also trying to determine the habitat needs of bumble
bees to aid in conservation efforts. Each species has slightly different needs
to thrive.
Bumble bees are different from other types of bees because
they are fuzzy and carry pollen in pollen baskets on their hind legs. The fuzz
keeps them warm so that they can be active in cooler temperatures than other non-fuzzy
bees.
Bumble bees are very important pollinators of agricultural crops.
Some crops
which bumble bees can pollinate include tomatoes, peppers, raspberry,
blueberry, kiwi, cashew, chives, cucumbers, apples, strawberries, alfalfa, some
citrus, melons, squashes, blackberries, soybeans, sunflower, cotton, flax,
beans, cherries, apricots, plums, almonds, nectarines, peaches, rosehips,
eggplants, and cranberries.
Bumble bees are generalists and have been recorded visiting
hundreds of native plant species. Their pollination services are likely very
important for maintaining various ecosystems. Many of the bees encountered on
the savanna were nectaring on showy tick trefoil, a native plant that was
flowering at the time of our visit.
Our day on the Savanna last week (July 19)was very successful.
Thankfully, it was one of the days with low humidity.
It seemed amazingly simple to catch the bees. Just look for
a bumble bee on a flower, lower a butterfly net over it and slide it carefully
into a clear plastic vial for identification. After each bee was identified, it
was released. Neither Colla nor her assistant have ever been stung.
The group found, and Sheila Colla and her field assistant,
Kristin, identified eight species of bumble bee at Alderville. Most were the Common
eastern bumble bee, Bombus impatiens.
One unusual species was found, the American bumble bee, Bombus pensylvanicus. This is a species that nests on the surface
of the ground, so requires dead plant material under which to nest. Most other
bumble bees nest under the ground.
The other six species found were Half-black bumble bee, Bombus vagans; Two-spotted bumble bee, B. bimaculatus; Confusing bumble bee, B. perplexus; Red-belted bumble bee, B. rufocinctus; Brown-belted bumble bee, B. griseocollis; and Tri-colored bumble bee, B. ternarius. Alas, no Rusty-patched bumble bees, Bombus affinis were found.
Any readers interested in learning more about bumble bees
can order Bumble Bees of the Eastern United
States through the third web site listed below. Colla is working on a field
guide to the bumble bees of North America, which should be published in the
winter of 2013. Watch for it!
For more information about bumble bees and the Rusty-patched
Bumble Bee in particular, go the the following web sites:
