10th August 2009

A few more visits today, first of all meeting up with Alan Leitch of RSPB in Orkney.  We looked at a number of ‘Birds & Bees’ crops, and a couple of areas of clover mix provided by BBCT.  A damp start, but the rain soon eased off and by lunchtime the sun was beginning to break through.  By this time, however, we had recorded Great Yellow Bumblebee in all the ‘Birds & Bees’ crops – the clover mixes (christened by Alan, ‘BBF’ or ‘Bumblebee Fodder’ mix) won’t flower fully until next year.  The number of Great Yellow Bumblebees in the crops is clearly determined by the amount of Phacelia present, despite the occasional use of Fodder Radish.  Thus, we saw anywhere between 1 and 30 Great Yellow Bumblebees, but interestingly almost all workers, with just a couple of males.  We also looked at a field that was now fallow, which were full of arable plants associated with cultivation.  Hemp Nettles were particularly abundant, and in among the many Garden Bumblebees and Common Carder Bees, there were two Great Yellow Bumblebee workers.

After lunch, I visited Dick and Pat Matson.  Dick is the Orkney Field Club chairman, and has been growing unharvested/game cover crops for ten years.  Dick has also sown a ‘BBF’ mix, to which he has added Phacelia.  This is in addition to another mix with reed canary grass and red clover, and another of Chicory (a tall, robust plant with large, blue, rather daisy-like flowers) with Sweet Clover – another component of the BBF mix.  There were Great Yellow Bumblebees collecting pollen at Phacelia and at the Red Clover (flowering now, i.e. a year ahead of the BBF mix).  The record from Red Clover is the first direct evidence that Great Yellow Bumblebees will collect pollen from these agricultural varieties.  We even saw one visiting the flowers of Chicory, presumably for nectar.  These were also visited by White-tailed and Heath Bumblebees, and both carder bees.  So, we managed six of Orkney’s seven species, but just couldn’t find the seventh – the Gipsy Cuckoo Bumblebee.

As I had made my way to Dick and Pat’s, I had seen a silage field with a fair amount of Red Clover.  I meant to enquire but on the way back the field was busily being cut.  An example of a beneficial management that is part of the farm system, outwith an agri-environment schemes.  However, despite the crop being cut now - just as we reach peak demand - there has still been an initial benefit to the bees, for at least some of the time.  The agricultural Red Clover varieties flower later than the native form, which is now all but finished flowering.  Given this continuity of flowering or native and agricultural Red Clover, it would be helpful for the bees to cut such crops later, but the farmer has to make a decision based on the likely quality of the silage (or haylage, or hay) and, importantly, the weather, as well as all the other jobs that need doing.

Another good day, made better by the spectacle of a Merlin mobbing a Hen Harrier along the road back to Stromness, though this was tempered by the worrying sight of a family car going into a ditch.  Thankfully, no-one was hurt and a tractor was on hand to tow the car out (which had sustained surprisingly little damage).