Posted by: Ross Gardner | March 1, 2021

Bumblebees abroad

A queen Buff-tailed Bumblebee (Bombus terrestris) coated in crocus pollen.

So not a fortnight after shivering in the sub-zero, snowy cold, spring raises its head above the wintry parapet for a first, tentative look around, giving all a much appreciated impression of what’s to come once winter has finally done its bit. Such caprices of prevailing conditions is, I think, one reason why the British are so renowned for spending much time discussing the weather. As I type a rather cold day is plummeting again towards zero and while that latter season is not done yet, its relenting does at least allow for a brief reacquainting with some welcome, familiar faces. The newts have returned to my garden pond and I was delighted to catch sight of a comma butterfly racing beneath the fresh spring sunshine. And we have, of course, the reappearance of the bumblebees.

Bumblebees are well-suited to the mood-swings encompassed by the British climate at this time of year, as also will be found other regions where an early flight-season might present them with some decidedly inclement periods of weather to deal with. There is actually a species, one Bombus polaris – the Arctic Bumblebee, that lives quite happily in the high-Arctic latitudes of Europe and North America. Being covered in furry layer of long hairs certainly helps in this regard, but they are able to employ other tricks. Not least of these is the ability, having disconnected the wings beforehand, to use their flight muscles to ‘shiver’ and raise their internal body temperature high enough for them to fly and forage. So even when basking alone is insufficient to achieve the required minimum internal flight temperature of 30°C, they are able to help things along enough for them to be active in air temperatures as low as around 10°C (I have on occasion observed bumblebees out and about in 8°C).

It is the buff-tailed bumblebee (Bombus terrestris) and the aptly named early bumblebee (Bombus pratorum) that are most likely to provide sightings of the ‘first bumblebee of the year’. Bumblebee colonies do not persist through the winter as with honey bees and only the queens hibernate. Having mated the previous summer, she will emerge from her torpor, firstly with task of finding food to replenish her reserves and bring her reproductive system back into function, then with the similarly pressing need to find a place to found her nest. The buff-tails this will be underground, often making use of old rodent burrows. The early bumblebee is less picky in terms elevation, as content to nest off the ground as it is under it.

Early Bumblebee (Bombus pratorum)

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