9th August 2009

Off to Stromness today, but rain was forecast for Monday so some bee searching was undertaken.  Up at the Sands of Evie, it is possible this year to walk alongside a ‘Birds & Bees’ crop, and seven Great Yellow Bumblebees were here (with one male using Perennial Sow-thistle by the beach).  I chatted with the local dog-walkers who were curious as to what the crop was for, and I was able to point out a Great Yellow Bumblebee at the Fodder Radish within the crop, though most were using the Phacelia.  A male Gypsy Cuckoo Bumblebee was here, the fist of this species I had seen in Orkney.  A roadside patch of the hybrid Woundwort didn’t have Great Yellows (it provides nectar, but doesn’t set seed – no pollen?), but it was time to meet up with Historic Scotland Ranger, Sandra Miller, for the 1 p.m. free tour of the amazing Ring of Brodgar (cunningly timed with the tour bus companies to be moderately quiet and 80,000 visitors a year go away very satisfied).  The RSPB manage the area and have another ‘Birds & Bees’ crop here, and I was able to catch both Moss Carder Bee and Great Yellow Bumblebee to show the group today, and say a little about bumblebees and their conservation.

Just nearby was a farmer who I had met at the Show, so we met up and had a look at one of his two ‘Birds & Bees’ crops.  I reached a total of 29 Great Yellow Bumblebees (at least 16 were males), but given that I have maybe covered a quarter of the crop, perhaps 100 or more Great Yellows were using this crop!  I had suspicions of two nests nearby.  After some waiting at one site, where males were regularly exploring vole runs and holes in the ground (and interacting with each other), a queen emerged from underground.  But this was a very worn old queen, so maybe she was just sheltering there?  Clearly, the males don’t know the difference between an old and a new queen, which is interesting.  Also here was a carder bee impaled on barbed wire.  Orkney regularly receives off-course migrant birds, and shrikes occasionally feature.  These ‘butcher birds’ frequently cache food by impaling them on thorns or on barbed wire fences, so I suspect one had visited the farm recently.

A final stop along the road, where there was a ‘Birds & Bees’ crop and also a lot of Lesser Knapweed along the roadside verge.  There were similar numbers of Great Yellows along an approximate 200m section of each, 19 in the crop and 15 along the verge. However, workers predominated in the crop (mainly on the Fodder Radish, though one large worker was collecting pollen from Phacelia), but most of those on the Knapweed were males.  It had cooled down a little by now, though hay-making continued apace on the farms, but in the morning the smaller workers had also been using the Fodder Radish.  Possibly the small workers can nectar more efficiently at Fodder Radish (one even had a little yellow pollen, possibly from this flower) and the larger ones more efficiently at Phacelia.  Having a range of wildflowers and crop flowers may reduce competition, as well as provide forage that smaller and larger workers can use more effectively.