3rd August 2009

Another mobile day, but starting bright and calm.  I visited Gavin and Kay Lockhart at Skerray, where they have a flower-rich meadow.  A good range of bumblebees, including the Broken-belted again, with tea, oatcakes and homemade blackcurrant jam!

 

Next to Armadale again, but the wind had really picked up.  There were very few bumblebees, but hundreds of honey bees, nearly all on the Lesser Knapweed.  Honey bees have short tongues, and would generally overlap little with Great Yellow Bumblebees in their use of flowers (white clover is an example of a flower they both use).  However, the Lesser Knapweed seems important for both at this time of year.  Whether there would be competition for resources is unknown, but is possible, given 50,000 workers in a honey bee hive compared with maybe 40 in a Great Yellow Bumblebee nest.  Both are present at Oldshoremore - though there are fewer honey bees there. There is some research showing that other bumblebee species perform more poorly the closer they are to honey bee hives, but the species studied were short-tongued species.  A tricky question, this, whether honey bee hives should be regulated where rare bumblebees are present.

 

Back into Caithness, and a patch of Marsh Woundwort at the roadside near Janetstown (the one near Thurso!) promted a stop.  It was windy, and in similar conditions in Orkney last year (Sanday) a similar patch held 27 Garden Bumblebees, 3 Moss Carders (no Common Carders on Sanday!) and a Great Yellow.  Since the Marsh Woundwort is often in ditches, it follows that it is a bit more sheltered, and the plant is rather robust, and stands up reasonably well in the wind.  Bees were certainly present, mostly Garden Bumblebees.  However, after a few miuntes of slow ‘verge crawling’, I spotted Great Yellow Bumblebee worker – fantastic!  Trying to get closer I inevitably slid gracelessly into the ditch and by the time I had extricated myself the bee was away.  I fetched the GPS from the car and walked back, and found either the same (or another?) worker Great Yellow about 25m further along.  We were in the 10km square ND06 – a new ‘hectad’ for Great Yellow Bumblebee??  If so, this would represent a westward extension of the range in Caithness, though admittedly by only 2km.  I was close to the B&B, so dropped my bags off and chatted with Barbara, whose family farm in the area.  Looking at the map, I noticed a disused quarry site near ‘my’ ditch.  Could this provide a refuge for Great Yellow Bumblebees, and could their use of quarries (for famous Caithness stone) partly explain the scatter of records inland.  I looked for the next nearest quarry, at Achscrabster.  Sure enough, a large patch of Marsh Woundwort held not just one, but two Great Yellow workers.  These were another 4km south, and another 2m (!) further west by the GPS.  I carried on, looking for more Marsh Woundwort.  Near Skiall, there were large patches on both sides of the road, but no Great Yellows.  Driving away, I slowly went by another patch more at eye level and had to stop sharply – another Great Yellow worker!  This one was more than 5km further west, almost into grid square NC.  So, Teresa is perhaps fully justified in being sure that the Great Yellow Bumblebee discovered in her car had not come from her garden in Thurso!

 

A celebratory fish supper at Scrabster Harbour, where Twite buzzed conversationally and another Broken-belted Bumblebee worker nearly allowed an ‘in focus’ photo opportunity.