Bilberry bumblebees and the National Trust

In my totally 'unbiased' view, these are the best UK bumblebee species.  Not only are they super fluffy like other bumblebees, they are adorably sized, and are found in one of my favourite habitat types; upland heath.

BB worker near Pumlumon (June 2018)

I have only seen this species once and I was lucky enough to almost study their foraging behaviour for my MSc thesis.  Unfortunately due to the current situation (coronavirus again!) the MSc field work didn't happen.  However, I have just finished writing up the 2020 season report from volunteer data from Bumblebees on the Mynd so this is a perfect time to share this! 

Here are some links to check out for these bumblebees and brain wash you all with their fluffiness.  I mean, look at their cute little red bums!

• Bumblebee Conservation Trust
• BWARS
• Steven Falk's Flickr
• BBCT Pollinating the Peak project by Rho Green at BBCT (@BuzzingPeak)
• Bumblebees on the Mynd National Trust project @BumbleontheMynd (see more below!)

A bit about bilberry bumblebees (BBs)

These bumblebees are small (12-16mm long) and very active, with red hairs over more than half their abdomen and a primrose yellow band on the top and bottom of the thorax; males have yellow facial hair too.  Be careful not to confuse them with other red-tailed bumblebees - these all have much less red on their abdomens male red-tails (B. lapidarius), early bumblebees (B. pratorum), red-shanked carder bees (B. ruderarius), and red-tailed cuckoo bumblebees (B. rupestris).

BB caste identification diagram from BBCT ID

They have specific habitat requirements and in the UK are usually found at altitudes above 300m.  They require dry heath with bilberry and heather mosaic and access to flower-rich grasslands/meadows for foraging on in the gap between bilberry and heather flowering periods.  In dry weather, you may find wet flush habitats yield more bees as the plants are more likely to be flowering than the heath areas.

 

BB habitat examples - from the Long Mynd and Stiperstones

BBs mostly feed on plants from the Ericaceae, Rosaceae, Fabaceae, Boraginaceae, Lamiaceae, Asteraceae, and Scrophulariaceae families but exact choices depend on time of year, location, and flower abundances.  For a more extensive list, see Appendix of my report (download for free here).

Pollen and nectar resources from Benton (2006).  (p) = important pollen resource.

BBs are active from April (overwintered queens) to September (new queens and males).  The diagram below shows a general bumblebee lifecycle of a colony with the emergence times of each caste. They nest in abandoned small mammal burrows in moorland and moorland edge habitats with dense vegetation cover of shrubs and mosses and usually have 50 (up to 120) workers per colony.  They can be parasitised by forest cuckoo bumblebees (B. sylvestris).

General lifecycle of BBs

BBs were much more widespread but are now are only found in localised hot spots and populations are unfortunately declining due to several threats.  These are climate change (affects food resources, emergence times of bees and flowers, and many other things), habitat loss and fragmentation, agricultural intensification and overgrazing (but correct grazing intensity can stimulate flowering), heather beetle plagues, and Phytophthora fungus attacking bilberry.

It was lovely to see a little BB feature with my photos on the recent FSC Discovering Bees Online run by BioLinks (Aaron Bhambra a.bhambra@field-studies-council.org) too.  There will be more in the FSC Field Identification of Bumblebees Online soon too and a section about Bumblebees on the Mynd project!

FSC Discovering Bees BB page

Email bumblebeesonthemynd@gmail.com or follow on Twitter @BumbleontheMynd

This is a National Trust project designed by Debbie Vivers at Carding Mill Valley and the Long Mynd.  The Mynd is an ideal site for BBs due to it's dry heath habitat type with bilberry-heather mosaic and wildflower meadows (Jinlye Meadows) close by.  Shropshire has a few historic records of bilberry bumblebees at Long Mynd, Clee Hill, Stiperstones, Rhos Fiddle (Clun) and Lower Shoreditch (Bishops Castle) giving ample opportunity for this project to contribute more data.

The main aims of the Bumblebees on the Mynd 2020 project were to:

1. Produce a baseline distribution map of the bilberry bumblebee
2. Establish if the bilberry bumblebee uses Jinlye Meadows
3. Observe which flowers bilberry bumblebees use on the Long Mynd and local gardens
4. Propose a standard method for monitoring bilberry bumblebees

We launched just before the first UK lockdown hit and it was lovely to meet all the local bee enthusiasts.  It was great to have Gill Perkins from BBCT introducing us and giving a great reminder of how important bumblebees are as well.  

A standardised method for surveying BBs was developed as bilberry can have dense leaf growth with the flowers hanging down inside the plant, making BBs difficult to observe.  If you see bilberry-attacking fungus Phytophthora around, be careful not to spread the infection on your boots to healthy areas.  Also be aware of ground-nesting birds and bumblebee nests when walking off pathed areas.  Before surveys begin, record date, time, weather, and general habitat type; if you are not comfortable being outside due to cold or wet weather, it is likely BBs will not be either!

Stop when you hear the 'Bombus buzz' and look for the bee - smaller bees have a higher pitch (listen to a recording by Debbie Vivers here).  Once you locate the bee, try to take a photograph or video to help ID it and the flower it is using, remember, more than half the abdomen of BBs is red.  Then you can record the location (I like the OS Locate app on Apple or Google Play) and any other bumblebee species you see.  Now move at least 25 paces away from the area before recording again to avoid recording the same individual twice.

If you find a nest, make sure you stay far enough away to avoid disturbing the BBs.  It may be useful to record the number of bees flying in and out and the nest location.

* It is important to submit records even if no bumblebees were observed, this applies for any species you survey *

Method for surveying BBs on the Mynd

The distribution of BBs on the Mynd (74 individuals) and Jinlye (10) was recorded to produce a baseline map using data from volunteers and showed that BBs were mostly linked to heath and heath with bracken habitat types, and bilberry flowers for foraging (on the meadows they used bird's-foot trefoil and white clover).  You can download my report from the 2020 season here to see the results, a review of everything I could find on the bilberry bumblebee, and our future plans for the project! 

BB caste observations and nest location (habitat data from National Trust monitoring in 2017).  All BBs were observed within the Long Mynd boundary but some points had low resolution location data so appear outside the boundary.

Bilberry Bumblebee in your Garden

During the first lockdown we altered the project to look for BBs in local gardens in the Strettons whilst volunteers  were unable to get onto the Long Mynd due to coronavirus restrictions.  The BB in your Garden report can be downloaded here.  

16 people engaged with the project finding white-tail, tree, early, red-tail, and common carder bumblebees and there was one record of a BB in an All Stretton garden which is close to Jinlye Meadows.

Onwards and upwards at the Mynd

We are applying for funding under the Stepping Stones project with the Green Recovery Challenge Fund 2021 and we hope to offer training for new volunteers, landowners, and enthusiasts and we aim to establish some BBCT BeeWalks in the local area.  Andy Perry is also writing a Species Recovery Plan for BBs on the Mynd area which can inform habitat management and suggest which nectar plants could  be planted to encourage bilberry bumblebees and other pollinators (improve planting with BBCT BeeKind or BeeWatch tools).

This year's (2021) new project will be focussed on all red-tail bumblebees and for more experienced surveyors there will also be a carder project to determine if the rarer species (moss carder B. muscorum and brown-banded carder B. humilis) are present on the Long Mynd as well as the common carder bumblebee (B. pascuorum).  

The re-launch event was recorded and can be watched below (Part 1 and Part 2) with a summary of the 2020 season results and identification training for red-tail identification.  The new carder project is also available below and on YouTube here with identification training.  We were lucky enough to recruit Richard Comont (BBCT Science Manager) to give a couple of talks and he had some great tips for identification and photographing bees!

 

Further reading:

• Benton, T., 2006.  Bumblebees: The Natural History & Identification of the Species Found in Britain, Collins.
• Hewson, R., 1986.  Relative Abundance and Foraging Habits of Bombus monticola on Heather Moorland in North-East Scotland.  The Naturalist 111, 73–78.
• Owens, N., 2020.  The Bumblebee Book.  NatureBureau.
• Prŷs-Jones, O.E., Corbet, S.A., 1987.  Bumblebees, Naturalists’ Handbooks.  Cambridge University Press.
• Rasmont, P., Roberts, S., Cederberg, B., Radchenko, V., Michez, D. 2015. Bombus monticola. The IUCN Red List of Threatened Species 2015: e.T13342506A57366294.
• Williams, D., 2011.  The Bilberry Bumblebee Bombus monticola on the Long Mynd, Shropshire.
• Yalden, P.E., 1983.  Foraging population size and distribution of Bombus monticola in the Peak District, England.  The Naturalist 108, 139–147.
• Yalden, P.E., 1982.  Pollen collected by the bumblebee Bombus monticola Smith in the Peak District, England.  Journal of Natural History 16, 823–832. 
• Yalden, P.E., 1984.  Flower visits by Bombus monticola Smith (Hymenoptera: Apidae) in the Peak District, England.  Entomologist’s Gazette (UK).