Movement along the A40

Yesterday morning as I lay in bed pondering on the minor miracle of continued survival and staring out of the window, what appeared to be a flurry of snowflakes swept along the valley. Reaching for my bins (dosen't everyone sleep with their binoculars handy by?) At 10x mag' The last of the snowflakes became blackheaded gulls, .
A couple more flurries passed by and then I decided it might be worth counting them , as you do. Between then and when the dogs howling for their breakfast and chickens agitation for liberation forced me to abandon the comforts of the pit and the cause of ornithology, (10 mins) upwards of 600 had passed by in groups rangeing from 30 -100.
This morning much the same occured so presumably these birds are travelling from their roost in the Fishguard area to feeding grounds (Rudbaxton landfill?)
It occured to me that this might be a whole lot of birds from a multitude of breeding grounds or one whole colony...any thoughts ?