When encountered in the alpine, Bombus melanopygus was sipping nectar from an Alpine Milk-vetch(?). Farther down the mountain it was seen on the ground, apparently sipping minerals from rocks. This was unusual.
The first observation of melanopygus was mundane: It was visiting vetch for nectar.
Later it was seen fighting over access to something on the ground.
The bumblebees then started puddling on the rocks. They were presumably sipping needed minerals in solution from the rocks. Butterflies do this, but it was an unexpected sighting for bees.
How did entomologists ever discern that this is what the bees were doing?
Jean, I don’t know. I could find only scant references to this behaviour among bumblebees.
I wonder if it has anything to do with the heat also?
Could you explain what you mean by “puddling”? Such interesting behaviour.
Della, from Wikipedia, “puddling is a behaviour most conspicuous in butterflies, but occurs in other animals as well, mainly insects; they seek out nutrients in certain moist substances such as rotting plant matter, mud and carrion and they suck up the fluid.” Alas, the article mentions bees, but not bumblebees. A bumblebee reference was found elsewhere.
I too, have observed such behaviour by butterflies…so thanks for this photo observation of the bumblers!
And some of those abundant alpine minerals wash down into creeks/rivers/lakes, suspended in snowmelt. In an un-dammed system, the minerals circulate freely to feed the primary levels of life in the water, which leads to fish…..very interesting to see the bees and fish connected in this way