Winter Bumblebees

Winter is a reclusive season, a time for silence, reflection and dormancy. It seems so still out there without bees buzzing about but we’re lucky we can be sure that they will emerge once again next year. There is something deeply reassuring about the repeating seasons and cycles of the natural world.

Ivy bearing bright yellow pollen in December

The typical lifecycle of a bumblebee is for queens to go into hibernation over the winter months and to emerge in spring to forage and produce eggs to build up a colony of female workers and males for the summer. Later in the season she produces new queens who go out and mate with the males. The old queen and the colony then die off leaving only the young mated queens to hibernate overwinter and start the cycle once more the next year.

I thought all bumblebees follow this cycle and all are in hibernation throughout December, January and February so I was shocked last week to find this one in our garden collecting big balls of bright yellow Ivy pollen on its legs. Usually this time of year it’s honeybees I’ve seen on Ivy. After some research I found out that in some parts of the UK this bee, the Buff Tailed bumblebee [Bombus Terrestris] has now become active throughout the winter too.

Bombus Terrestris

It is estimated that Buff Tailed queens are visiting 6000 flowers a day at this time of year in order to collect enough nectar to maintain the heat required to brood her eggs. When she is away from the nest foraging the eggs will cool so her trips need to be short and its important she finds forage close by. It is often overlooked that we should grow plants that provide nectar and pollen throughout the winter for the non-hibernating honeybees and now also the Buff Tails. Key plants for the Buff Tails over winter are Mahonia, Strawberry Tree, Vibernum Arrowwood Dawn, Winter Honeysuckle, Rhododendron, Clematis and Ivy.

bumblebee in december 1Having not seen a bee for a while, I was very excited to see the Buff Tailed. There is however a slightly unnerving side to the story of my winter bumblebee sighting. With some further research it seems that this winter appearance could be a result of commercially bred, non-native bumblebees escaping from farms into the wild and mating with the Buff Tails, creating a winter hardy hybrid bee. Maybe this is what I’ve seen? BWARS [The Bees, Wasps and Ants Recording Society] is carrying out a study on the winter activity of the Buff Tails this year so I submitted my sighting to their website.

“Captive nests, not of the British sub-species, are now used by commercial tomato and fruit growers for pollination. Unfortunately, some sexuals may escape and inter-breed with wild bees.” BWARS

This sounds a bit concerning. Bees shape our landscape with their pollination trips and if the behavior of the bees changes, then so do plant responses. Should we focus on increasing the intrinsic biodiversity of our farms to ensure healthy wild bee populations so we don’t need to import commercially bred species of bumbles? Of course. And why is importing non-native bees not regulated to prevent hybridisation and the spread of disease? There must be a lot of money in the bumblebee breeding business for this to be overlooking this.

The alternative explanation for the Buff Tails activity over winter is climate change with mild winter weather disturbing their hibernation earlier. If our winters continue to warm, it seems more bees will respond by being more active and we will see changes to our whole pollinator and plant cycles.

Bee tongueThis active winter behaviour has only been observed since the late 1990’s and is still a bit of a mystery to us. Whatever the cause for this winter activity, I sure was pleased to see her but its also reminded me that we are living through changing times for the little bees, for the planet and for us. Who knows what winters will be like in 30 years?

Keep a look out for those winter Buff Tails!