Saving the Great Yellow Bumblebee

To give some background, their main focus currently in Scotland is the conservation and creation of habitat to support the Great Yellow Bumblebee, Bombus distinguendus (GYB). Within the UK, this iconic and rare species is now found only in five known population centres, all in remote areas of Scotland (namely, Caithness, Sutherland, Orkney, Inner Hebrides and Outer Hebrides). The principle cause of bumblebee declines across the UK as a whole is the loss of flower-rich meadows linked to the intensification of farming and grazing practices in the last 80 years. Scotland has escaped the majority of these effects as it has much more marginally productive ground plus a strong cultural tendency towards low-intensity farming; but even here some GYB populations are demonstrably in decline (RSPB data).

The initial problem was that much of the data about GYB is out of date (10 years or older). Without up-to-date data, it is much harder to direct their limited resources to the best effect. The lack of survey effort is related to the low human population, and there is also a need for additional tailored support to encourage continuity of volunteer surveying. These three main problems were the ones They sought to address through this project.

The project aims to build on their past work in Scotland, raising awareness about bumblebees, and converting this awareness into action. Their work in 2019 increased their surveying efforts and was successful in encouraging more individuals to assist with generating new records through the popular ‘Square of the Week’ scheme, and through an increase in BeeWalk transects set up within the project area. People have gained skills and the confidence to use those skills to help monitor the plight of the rare bees local to their area.

The increased levels of surveying efforts are vital to address knowledge gaps, enabling them to get a much more accurate picture of GYB distribution and monitor populations. They will be able to evaluate whether their advice is having the right effect and adapt their recommendations if not.

Through the project, more landowners will be managing land for rare bumblebees and will be more aware of the needs of GYB. They hope this will have knock-on benefits in encouraging even more landowners to get involved with the project and seek to provide even more high quality habitats for pollinators, through an innovative cluster farm approach.

At the end of the project, they will have a better understanding of the ecology, habitat needs and distribution of GYB, which they can share with their partner organisation’s and influence local change in management practices to benefit this rare species.

The last mainland UK populations of Great yellow bumblebees (GYB) are found in Caithness and Sutherland where flower-rich machair can still be found and traditional crofting practices are maintained. It is vitally important to continue to protect and expand these areas to ensure that the GYB, and the many other insect species that benefit from this flower-rich landscape, don’t disappear from the UK mainland. One of the species at risk includes the Moss Carder bumblebee, Bombus muscorum, which shares range and habitat with GYB, and is listed as Vulnerable in the IUCN European red list of bees. Both species are priority species in Scotland (Scottish Biodiversity List, Scottish Invertebrate Strategy).

Away from these mainland sites, the only viable populations of GYB are found in the Inner and Outer Hebrides, and Orkney. These island populations are currently considered relatively healthy because of a strong cultural tradition of low intensity crofting management; however, they are particularly at risk from changes in habitat use and many crofts are becoming abandoned or over-grazed. Island populations are, by their nature, fragmented and particularly vulnerable to loss because of the lack of connectivity with other populations.

They work with the RSPB and other environmental organisations in all areas where their interests coincide. The region which has the least available input from RSPB staff is on the Outer Hebrides. Therefore, they have decided to focus their efforts there, so that the whole population of GYB can be covered and simultaneously, they can fill knowledge gaps. They will continue to liaise closely with RSPB over GYB populations in other island areas and keep a watching brief across all areas where GYB is found.

Generating survey records of GYB has been challenging due to the scarcity of the species (over quite large geographical areas) and the high survey effort needed to find and then monitor GYB. The field season is short and very weather dependent, and low human populations within its distribution area present challenges around volunteer recruitment e.g. for BeeWalk monitoring. Distribution data is now becoming out of date and they do not have enough abundance data to be able to determine the current GYB population status.
This limits how well they can target conservation initiatives for GYB and weakens the value of the dataset as a tool to help farmers and crofter’s access agri-environment funding for options which benefit GYB. Saving the Great Bumblebee is also lacking data on suitable forage sites and the availability of early, middle and late forage for GYB. This is again limiting their conservation efforts. They have addressed this in the project by directing more Conservation Officer (CO) time towards survey work (in Caithness and parts of Sutherland) and bringing in ecological consultants to carry out targeted surveys in the Outer Hebrides and NW Sutherland.

This is crucial in enabling them to get an accurate picture of GYB distribution, monitor populations and also evaluate whether their advice is having the right effect, and adapt their recommendations if not.

The second challenge was that two of their training courses were not delivered in 2019 due to no demand (no bookings). Saving the Great Bumblebee addressed this by remaining open to opportunities and adhoc requests, delivering a second course in NW Sutherland where there was high demand and an additional course in the Outer Hebrides with a community group that had got in touch to request an advisory visit.

Thirdly, Covid-19 has been a massive challenge in 2020, with key staff on the ground in lockdown until early July, knocking out around half the field season. Several planned events and meetings had to be cancelled. They addressed this by prioritising effectively, maintaining open communication with their funders and adjusting the timescale of the deliverables where there was no mitigation possible.