176
THE ESSEX NATURALIST
Great Canfield (Map Ref. 004197) 113; Ashdon (Map Ref. 597403)
104.
Comparison with Previous Published Work
A census of Rooks was carried out by A. Darlington in
1956/57 and published in Darlington (1957). This was a very
full account of the Rook as a breeding species in Essex. It is
useful to compare these results with the present account.
In Darlington's report there were 18,252 pairs of rooks in 822
rookeries. A rookery was clearly defined as all nests separated
Figure 1. Distribution of rookeries in Essex, 1966.