2018’s extreme weather led to a tough year for the UK’s bumblebees

2018 was a tough year for many of the UK’s 24 bumblebee species according to a report released today by the Bumblebee Conservation Trust.

The new report summarises trends in the UK’s bumblebee populations, using data gathered every year from 2010 by a country wide network of hundreds of ‘BeeWalker’ citizen scientists.

The cold weather of the ‘Beast from the East’ in late February and early March delayed the beginning of the 2018 bumblebee season. Most bumblebee species got off to a slow start and only reached normal numbers in July, suggesting bumblebee queens were late out of hibernation and subsequently slow to produce big numbers of bumblebee workers.  As a result many of the UK’s bumblebee species declined more quickly than normal as the year progressed, particularly as the summer heatwave reduced the available food, as flowers wilted in the unusual warmth.

The spring specialist Early bumblebee (Bombus pratorum) had a particularly bad year, its worst since the near-constant rain of 2012. Several other species, normally common in people’s gardens had poor years, including the Garden bumblebee (Bombus hortorum), the Buff-tailed bumblebee (Bombus terrestris), the Heath bumblebee (Bombus jonellus) and the White-tailed bumblebee (Bombus lucorum aggregate)

A small number of rare species had very good years in 2018. This list included the Brown-banded carder bee (Bombus humilis), the Shrill carder bee (Bombus sylvarum), and the Large Garden Ruderal bumblebee (Bombus ruderatus), all warmth-loving species which reach the northern edge of their geographical ranges in England and Wales. All three of these species are currently the focus of projects to create and conserve suitable habitat. They are also traditionally late-emerging species, so the cold 2018 March was likely to have had a minimal effect on numbers.

Dr Richard Comont, Science Manager at the Bumblebee Conservation Trust said, “Whilst it is great to see the four ‘biggest species winners’ from our latest ‘BeeWalk’ data are rare bumblebees, it’s concerning to see four of our seven commonest bumblebees have declined over the last nine years.”

The impact of the 2018 heatwave has raised concerns about the number of bumblebee queens that made it into hibernation over the 2018 to 2019 winter. 2018 was the worst year for bumblebee abundance – the number of individuals per species – recorded by BeeWalk since 2012. This could have a potential knock on effect on populations in 2019. The likelihood of long heatwaves like 2018 becoming more frequent could cause problems for Britain’s bumblebee populations in the longer term.

Gill Perkins, CEO Bumblebee Conservation Trust said, “I greatly welcome the latest BeeWalk report and thank all those who ‘Beewalked’ in 2018. Their amazing efforts allow us to answer the critical question ‘how the UK’s bumblebees are doing’ using high quality evidence. I’m particularly concerned by the declines reported in some of our common garden species. We all need to make sure our gardens, parks and greenspaces are bumblebee-friendly to stop today’s common species becoming tomorrow’s rarities.”

Dr Comont added, “BeeWalk is unique. It allows us to see patterns and trends that we can’t get from any other dataset. It’s fantastic that almost 500 people go out every month from March to October to survey bumblebees, building on the support and training we supply them with from the Bumblebee Conservation Trust. Their hard work gives us an unparalleled ability to understand exactly how bumblebees are doing across the UK.”

BeeWalk statistics and facts

  • 482 BeeWalkers submitted data from 559 sites in 2018 (some BeeWalkers monitor multiple sites)
  • By the end of 2018 382,563 individual bumblebees had been recorded over nine years of BeeWalks
  • Most remote transect set up in 2018 – Arnisdale on the West coast of Scotland
  • Most southerly transect set up in 2018 – located on the Isles of Scilly
  • BeeWalk produces trend data for almost all of the UK’s 24 bumblebee species, one exception being the Great Yellow bumblebee which is now restricted to very limited areas of Northern Scotland.

The full BeeWalk annual report can be downloaded here.

To help monitor the UK’s bumblebees please visit www.beewalk.org.uk

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