Our latest guest blog comes from Tiree, ‘the sunshine island’. Low-lying and fertile, it boasts excellent areas of machair. Although often windy – there was once a wind of 116mph recorded here – it is a fabulous place to enjoy nature, and as Janet Bowler’s blog reveals there has been an exciting finale to the great yellow bumblebee community project on the Isle of Tiree!
By Janet Bowler
It has been a while since my last guest blog about Tiree’s Great Yellow Bumblebee Project, the final one of which should really have been produced in late 2020. But as with so many other efforts, the covid-19 pandemic disrupted some elements of the project, notably by restricting the number of bee surveyors who could visit the island and by delaying the publication of the children’s storybook. Looking on the bright side, however, these delays have enabled inclusion of an extra year’s worth of exciting observations.
Although we didn’t have the assistance of additional surveyors in 2021 (or 2020), a handful of locals conducted a few surveys at key sites in August, the busiest month for GYBB colonies when workers, queens, daughter queens and males are all active. We were astounded with our findings: we each counted many more individuals per hour than in any previous year. Excited by this result, we plotted the August data from a few key sites (Figure 1). The data probably wouldn’t stand up to rigorous statistical scrutiny, but they do give an overall impression of GYBB activity over the duration of the project, and an indication of the most productive sites.
It could be argued that the increase in counts is due to increasing spotting skills amongst the surveyors, but as trends varied between some sites, and as all observers recorded significantly more GYBBs in August 2021, it seems more likely to be a true reflection of numbers. In any case, we can attribute the changes between years to weather conditions.
Growth of the bees’ forage plants was hindered by a prolonged summer drought across all sites in 2018. 2019 was mostly cold and wet but warmed up in late summer. The weather in 2020 created a roller-coaster ride for flowers and bees, but finally settled to warm, wet and sunny conditions resulting in simultaneous blooming of all the GYBBs favoured forage flowers, finally enabling successful breeding and a larger number of daughter queens to stock up for, and survive, winter hibernation.
Between April and June in 2021 was cold and no queens emerged from hibernation until warmer weather in late June, when larger numbers of queens than normal were recorded. Summer 2021 continued warm and windless, with occasional rain relieving the drought. This enabled copious machair flowers to support higher breeding rates for the GYBB colonies and, therefore, higher counts. Hopefully, this means that even more daughter queens will emerge from hibernation in Spring 2022.
The above summary demonstrates the impact that the vagaries of the Spring-Summer weather can have on the GYBB’s success, and why, therefore, the species requires such large areas of diverse key forage flowers to ensure that, regardless of the weather, there are always resources available to keep the species going.
A Nest at Caoles
Against all the odds, two eagle-eyed visitors discovered a GYBB nest as they were cycling along the road to Caoles, at the east end of the island. Knowing that this was an important species (through this project), they stayed a while to watch and saw several bees disappear into the same patch of vegetation in the roadside bank. This was an important find. Not only was it just the third GYBB nest found during the entire five years of the project, but it was also close to an area of machair that GYBBs seemed to have disappeared from, raising our hopes that the population in that area could thrive again.
Sensory garden success
Most of the ‘mini-machairs’ we sowed throughout the island in 2018 bloomed each year providing nectar and pollen for nesting bumblebees. One in particular was sensational – in the back garden at Tigh a’ Rudha Care Home.
It was a late addition, only being planted in 2019 as part of their Sensory Garden project, but it may be one of the most successful. In 2021, it bloomed spectacularly, delighting the residents with a yellow carpet of kidney vetch, bird’s-foot trefoil and autumn hawkbit, along with scatterings of red and white clovers, and tufted vetch, all favoured by great yellow bumblebees.
With much celebrating, the story about Betty – a great yellow bumblebee, created by Tiree Primary School children, was finally published in November 2021. Beataidh Banrigh – Super Bee is a warm and funny tale of friendship and wildlife conservation. It includes a fun plot, great characters and some zingy dialogue, and is told in both Gaelic and English. The children’s drawings, transformed into stunning illustrations by local artist Rou Worsley, are sumptuous in print. There is a page of useful and fascinating Bee Facts (some of which are needed to explain some of the strange behaviours of the characters!), and Forewords by Gill Perkins – CEO of the Bumblebee Conservation Trust, and Roddy MacLean – Gaelic broadcaster, writer and naturalist. What a high note to end Tiree’s Great Yellow Bumblebee Project on!
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