Increasingly seen along the Dorset coast and on the north Dorset downs
The raven is a resident species in Dorset but it is my perception, with no data to support it, that they are less numerous than ten years ago. It may just be that I do not get the wilder and more remote areas that ravens tend to favour these days but I am surprised that there have not more tweeted reports of raven in the last couple of years. The raven nests around the cliffs and remote places of the western half of England and Scotland and throughout Wales; Dorset is at the extreme eastern edge of their range in England and that may be why numbers fluctuate. I recall that back in the 1970s and 1980s ravens were very, very scarce and there is no doubt numbers have recovered since then but may be that improved population level is now reversing again? I am sure that somewhere there is some reliable data on this.
Although a resident species there are weeks when ravens are not reported in your tweets at all with April and June seemingly the time when reports dry up. Whether this is an absence of ravens or just an absence of records is hard to tell, there does not seem to me to be an obvious reason for the gaps other than, as ravens nest early in the year, this is when they are sitting on eggs? That might account for the April gap but not June; may be June is moult related? I can only speculate.
There are reports of raven from over sixty sites in Dorset and they are obviously widespread. Many reports are coastal, others from the Poole Basin heaths, some are from Cranborne Chase and others from the remote parts of the chalk spine from Bridport towards Shaftesbury. They range from Charmouth in the west to Christchurch harbour in the the east and up to Fontmell Down in the north of the county.
The most regular reports come from Durlston Country Park and that is probably the best place to go to get raven on to your Dorset list.