Roosts in Valley

Given the dearth of bird movements in desperation for something to report here is a bit on daily movements of corvids.
The black members of the family seem to be quite flexible in their choice of roosting place.  It seems to vary dependent on the use of the racecourse and aldersley stadium.
The number of birds is around 400 most obviously Jackdaws which are the most vocal but including Crows and Rooks.  Site choices are Aldersley canal junction, the racecourse by the pool, the stadium poplars or the water bridge copse.
The Magpies are more picky always choosing the trees and bushes around Oxley bank, height varying a bit with wind strength but generally lower than their monochrome cousins.  A few days ago I went down about half four and counted 81 already there and then another 50 arriving singly from the West over the canal.  returning to the roost I counted 133 which must be an underestimate because they arrive from all directions.  Yesterday noted 15 in a pre-roost by Water bridge, where there were two contrasting Little Grebes one in full summer plumage the other still in full winter.  Wonder if it has anything to do with age of the bird?
Finally I found the finch flock(50ish) which usually graces the stadium just north of Autherley junction; mainly chaffinch , goldfinch and lesser redpoll with at least one siskin.