Since the 1990s, sightings have shown that buff-tailed bumblebees (Bombus terrestris) are breaking from their usual seasonal patterns. Rather than entering dormancy, some queens are setting up nests in autumn, producing workers, males, and even mating pairs during a period when bumblebee activity was once virtually unknown. This remarkable shift is one of the clearest insect responses to our warming climate.

Why is this happening? Milder winters are a key driver. Warmer temperatures allow queens to remain active instead of entering their dormant phase, while towns create a micro-climate known as the Urban Heat Island effect, keeping city habitats warmer than surrounding countryside. Urban gardens, parks and amenity plantings also provide something essential: winter flowers. Species such as mahonia, winter honeysuckle, heather and even late-flowering ivy now supply nectar and pollen at a time of year when wild forage was once scarce.

These food sources are proving enough to sustain entire winter nests of buff-tailed bumblebees, and in some cases these colonies survive long enough to produce new queens in early spring. Recordings show winter activity from the south coast all the way to Scotland: evidence of a rapidly shifting seasonal pattern across the country.

Buff-tailed bumblebees are striking insects: queens are large and furry, with a black body, bright yellow bands across the thorax and abdomen, and a distinctive white tail. Workers are slightly smaller but share the same bold colouring, while males can have a more orangey or golden hue. These vivid patterns make them easy to spot against the muted tones of late autumn gardens and parks.

Other bumblebee species are also seen in winter, though often these are early-emerging queens roused by mild weather rather than genuine winter nesting attempts. Still, climate-driven temperature swings are risky for all species. A warm spell in January may wake a queen too early, only for cold weather to return before her essential early-spring flowers appear.