Great and Lesser Black-backed Gulls in North Wales

I N their lengthy and elaborate paper on numerical fluctuations of the Great Black-backed Gull, Larus marinus (Proc. Zool. Soc, 1933, pp. 191-209), Messrs. T. H. Harrisson and H. C. Hurrell suggest t h a t Anglesey has been an important centre of dispersal and consequently an important factor in the remarkable increase in the numbers of this species during the last thirty years. They surmise--the ...