The Gape-worm (Syngamus trachea Montagu) in rooks (Corvus Frugilegus L.)

Abstract

During the early part of 1928, a census of the rookeries in the Oxford district was carried out by the Oxford Bird Census organised by Mr E. M. Nicholson. This work raised a number of problems, of which one of the most important was that of natural checks to the numbers of rooks. Although shooting of the young rooks is one of the greatest checks on their population, Mr Nicholson's observations showed that there must also be a mortality amongst the nestlings. Lewis (1925, 1926 b) has shown that gape-worms are common in starlings (Sturnus vulgaris), and it seemed possible to us that this parasite might also be sufficiently common in rooks to cause deaths among the young birds. The gape-worm had already been recorded from the rook by Lewis (1926 a) and Baylis (1928), so that the possibility seemed well worth investigating.