The ecology of the American grey squirrel (Sciurus carolinensis Gmelin) in the British Isles.

Abstract

The investigation which has provided the subject-matter of this paper forms part of a scheme of research into the numbers and fluctuations of wild rodents under the direction of Mr. Charles Elton, to whom my thanks are due for continual advice and assistance. The work is being financed by a grant from the Empire Marketing Board, and has been carried out, by kind permission of Prof. E. S. Goodrich, F. R. S., in the Department, of Zoology and Comparative Anatomy at Oxford.

Information regarding the spread of the grey squirrel in the British Isles, and the fluctuations in numbers of the red squirrel and other rodents, has been obtained from a number of correspondents throughout the country by means of questionnaires and through the agency of the Press, as well as by personal interviews and direct observation. My thanks are due to all those who have so readily given me information regarding squirrels in districts of which they have special knowledge; a list, is given of the people whose information has been used in compiling this paper, but I must apologise for the omission of the names of many who have given corroborative and negative evidence on certain points, and whose evidence is none the less valuable and appreciated. I wish especially to thank the staff of the Forestry Commission for the assistance they have given in this investigation, Mr. R. E. Knowles, the late Prof. Kennedy Orton, Mr. S. Smith, F.Z.S., Major M. Portal, and Mr. F. Faraker for their kindness in undertaking special inquiries in their particular areas on my behalf. My thanks are also due to Mr. Oliver Watney for giving me exceptional facilities and practical assistance in studying the grey squirrels of Wychwood Forest, Oxfordshire.

It is realised that the results of an investigation of this kind can never be said to be complete, and the evidence on such points as the first appearance of grey squirrels in particular districts must always be liable to minor corrections. For this reason, negative evidence has, except in certain cases, been avoided in the compilation of maps, tables, etc. Whereas positive evidence of the occurrence of squirrels in a particular district is undeniable, negative evidence is rarely certain and may often be the result of limited observation.

Numerous general reports relative to the food and habits of the grey squirrel, such as "eats birds' eggs" and "has exterminated all the red squirrels," have had to be neglected in this paper, and only the evidence backed by detailed observation is included.