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Bumblebees vs extreme Photo: John Hubble Unsurprisingly then, 2018 was not a Photo bottom left: Brown-banded
good year overall for bumblebees, with
carder bee (Bombus humilis) by Ray
Reeves; photo Early bumblebee
a noticeable drop-off from 2017. The
weather: BeeWalk 2018 results early species seemed to fare worst, and the (Bombus pratorum) by Kate Jaconello
Early and Buff-tailed bumblebees (Bombus
pratorum and terrestris) both had one of
their worst years in BeeWalk.
This is likely to be the result of early-
emerging queens dying in the March snows,
with the survivors then struggling to forage
as they went straight into the heatwave.
The Buff-tailed bumblebee is also more
nectar-focused than most other bumblebees
thanks to having larger nests - so it may
have suffered disproportionately from the
effects of drought.
But it wasn’t all doom and gloom. There are
several species of bumblebee which reach
the northern edge of their ranges in Britain,
By Dr Richard Comont, Science Manager and which do better in warmer conditions.
In fact, the top four most-increasing species
in BeeWalk were the rare Red-shanked
2018 was a year of weather extremes. This presented bumblebees with carder bee, Shrill carder bee, Ruderal
The start of the bumblebee season something of a challenge. Although and Brown-banded bumblebees (Bombus
in March was delayed by the ‘Beast insects generally like warmer weather - ruderarius, slyvarum, ruderatus and
from the East’, a spell of very cold butterflies had a good 2018, for instance humilis)!
weather which left a foot of snow on the - bumblebees are slightly different. On
ground in many places. After Easter the really hot days they struggle to fly - their The Brown-banded carder bee (Bombus
weather changed for the warmer – a huge flight muscles generate a lot of humilis) is particularly interesting from a
six-week run of daytime temperatures heat which they need to vent, and they conservation point of view. It has been
o
above 30 C made the summer the joint- just can’t do that well enough to be able showing signs of spreading out across
warmest ever, level with 1976, 2003, to fly when air temperatures are much southern Britain in recent years, and the
o
and 2006. above 30 C. Secondly, bumblebees species did very well in 2018’s hot summer
need nectar to provide the energy to fly. – it will be interesting to see if these greater
In droughts, flowers don’t produce as abundances lead to individuals dispersing
much nectar (there’s not much spare and turning up in new places during 2019.
water to make it with), and the flowers
themselves don’t last as long, going
over sooner. So there’s not as much To read the
food available and the bees struggle latest BeeWalk
to reach it - not a great combination for Report 2019, visit
survival.
bumblebeeconservation.
org/publications/
Photo: White tailed bumblebee
(Bombus lucorum) by David Geddes
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