At the time of writing (December 2018) the wheatear has more entries in the Nature of Dorset database than any other species; 460 in 23 months. Initially I found that surprising but then just what species would I have thought would be number one? With some reflection the reasons, I think, become more apparent.
First and foremost the wheatear is not a 'usual' Dorset bird (if there is such a thing as a usual Dorset bird). It is not a species resident all year round or for any extended length of time during a season. It is not regarded as a breeding species in Dorset either although there is an indication that at least one pair may have bred successfully here in 2018. So not being a 'usual' Dorset species it engenders a degree of interest when seen and that means it is more likely to get a mention in a tweet.
The wheatear is, like many other species, a 'passage migrant'; seen in spring on its way north to its breeding grounds on the moors up north and in autumn on their way back to southern climes for the winter. What marks the wheatear out as special is that it tends to be one of the earliest movers and so their appearance in Dorset usually signals the start of the migration season and that engenders tweets as observers see their first of the season or see one after the main flow seems to have finished. The chart of weekly records shows this quite well with the earliest spring arrivals coming in around week 10 which is mid-March, long before many other migrant species. They reach their peak around week 16 (early April) and the inflow is over by about week 21 or early May. The autumn departure seem to start around week 30 (late July) again before many other species start south. Departures peak in week 36, or late August, but they can still be seen right through until week 43, mid to late October.
On top of this is the fact that the wheatear does not seem to migrate in flocks but as single birds. This means that they can turn up almost anywhere along the coast in Dorset in small numbers rather than a large number being seen in one place. A look at the distribution map of sightings quite clearly shows this with hardly a coastal site where they have not been recorded over the last two years. They are also highly visible birds as they seem to prefer open rough grassy habitats where they tend to perch on exposed rocks or on fence posts and the like. Couple this with their characteristic upright stance and their unmistakable white rump when they fly and they are easy to spot.
If you not seen one then Portland and Ferrybridge are probably the best places to go in April and August.