The common sandpiper is not a Dorset resident species; it is a passage migrant seen whilst making its way north to breed in spring and south to warmer climes in autumn. It produces a good number of reports from Dorset birders but it is never seen in big numbers, they tend to rather solitary birds.
Looking at the charts the first thing I notice is that exactly the same number of reports were found in 2018 as there were in 2017, 122 in both years. I am sure there is nothing too significant in this but it does seem quite coincidental. The second thing I notice is that despite it being a passage migrant there are occasional reports of common sandpiper in Dorset during both the summer and winter months when reports would not normally be expected so it always pays to expect the unexpected when it comes to bird watching.
Despite the unseasonable reports the weekly chart shows a fairly typical passage migrant shape with a sudden, steep influx of birds in spring from week 15 to 18 which shows that mainly return in a single, short wave in April stopping briefly to feed and rest before pressing on to their nesting grounds. The autumn return journey is a much more relaxed affair with birds passing through from about week 26 until week 40 meaning they are likely to be visible from late July through until late September. During the autumn they may stay over for few days before resuming their long journey to Africa.
The distribution map shows that they are usually reported from coastal sites. This is partly because as 'waders' this would be the sort of habitat one would expect to see them in but also, of course, these are the sites most watched by Dorset birders. The majority of records come from two very closely watched sites at Abbotsbury swannery and at Lytchett Bay with frequent records also from Ferrybridge and Lodmoor.
It is difficult to be precise about when and where you might see common sandpiper, this is another of those species where you need to watch the news headlines and act as soon as reports start to come in.