July 2010

A flurry of email activity at the start of the month before heading north to Orkney.  We were able to publicise the success of National Insect Week in the local Tiree paper, An Tirisdeach, and also follow up on an intriguing project by the Macaulay Institute, who are resurveying areas of machair that were looked at in the 1970s.  There is the chance to survey great yellow bumblebee numbers in relation to these plant surveys, which could indicate preferred management options for bees, and – very tentatively – suggest what possible impact on bee numbers any changes in vegetation and land use over the past 30+ years may have had.

I broke my journey north at a few places before catching the evening ferry, looking at the availability of spring flowers for great yellow bumblebees.  Thankfully, after a long day, I didn’t have far to go to find the B&B (The Inn at St Mary’s, Holm) which was wonderful.  I took a short walk before breakfast on the opposite side of the road where there was perhaps a total area of red clover patches totalling perhaps 20m² in an area of 100m². Remarkably, there were four great yellow bumblebee queens here (one was rather small), three of which had collected pollen!  The numbers of great yellow bumblebees certainly do seem to have increased on Orkney, probably due to a combination of good weather and beneficial management being carried out by farmers there. 

One of my reasons to visit now was to check the progress of a small number of ‘pollen & nectar’ mixes using agricultural legumes.  Three of the five sites had done well, and all of these had great yellow bumblebees.  At one of these sites, hosted by Dick Matson, we also had a quick look at bees in the garden, at Dick’s suggestion.  I looked at a patch of Geranium where there was a slow-moving bumblebee and did something of a double take – surely this is a Barbut’s cuckoo bumblebee?!  It looked just like the ones I saw with Pippa in May, with a slightly dingy yellow ‘collar’.  Catching the bee allowed us to see the distinctive ridges on the underside to confirm that this was indeed Bombus barbutellus, a rare and localised species in Scotland – the nearest records to Orkney are from Aberdeen!  John Crossley circulated the information and remarkably two more females were seen in July, another on Mainland Orkney and one on Egilsay.  It seems there are some older records from Orkney, and a photo of a good candidate was taken the year before.

I also attended an Open Day run by the Scottish Agricultural College concerning the use of clover in silage (see photo of Luing cattle, photo courtesy of Graham Scott).  The use of red clover in particular has increased, and young cattle can put on nearly 1kg a day on this rich diet!  I also visited a couple of farms in the company of Graham Scott of SAC, to look at suitability of sites for great yellow bumblebee and discuss management.  In contrast to the Open Day, the weather was terrible, but no excuse not to look at flowers.

I left Orkney on the afternoon ferry and headed to Bettyhill to join Paul Castle for a guided walk at the Farr Glebe bumblebee sanctuary.  The rain had abated and we had a beautiful evening with the few brave souls that had taken a gamble on the weather improving.  A great yellow bumblebee queen was busy collecting pollen, with perhaps the same individual returning within 20 minutes to gather more pollen.  After the walk, Paul and I looked at the Naverside area, where there is abundant kidney vetch this year, and also the peculiar legume, purple oxytropis.  We saw another great yellow bumblebee queen here.

Much of the remainder of the month was spent visiting sites to assess flower richness, suitability for Species Action Framework demonstration sites, or visiting farms. It was exciting to confirm that great yellow bumblebee was still present at Melvich, where they had been found for the first time last year by Paul.  The pollen & nectar mix plots on Caithness farms had now started to flower, and by the end of the month there were a number of records of great yellow bumblebees from the volunteers monitoring the sites.  There was an encouraging number of sightings of workers from the third week in July.  For me, a particular highlight was seeing my first great yellow bumblebees at Durness, with workers collecting pollen from red clover and a queen prospecting for a nest site at a stone wall.  In Caithness reports of workers included several away from the pollen & nectar mix plots.  This was the first chance we had to see which of the wildflowers were being used as pollen sources. Several of the verges were very flower rich, and the use of red clover and tufted vetch were not a surprise, but meadowsweet was.  The past two years of the Bumblebee Habitat Project has revolutionised our understanding of great yellow bumblebees in Caithness, with much cause for optimism.

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