Art of Bird-Watching. By E. M. Xicholson. (Witherby.) ios. 6d. net. Illustrated. T H I S is a practical and stimulating book which can strongly be recommended to the attention of bird-watchers. It is something more than Thethat, for it raises fundamental questions of aim and methods. To these I shall return. Here let me sav that on the praetieal side the book will make a special appeal to those interested in the biology of field work ; it gives good detailed accounts of bird census work, ringing and trapping, and of the study of the inter-relations of birds, other animals and plants, now familiar as ecology. Generally useful are the hints on field equipment, method, and subjects for study. From the wide range of matters dealt with it is possible here to select only a few for adequate comment. Among these I include the subject of the bird-watcher's chief implement, his field-glass. It would be an interesting and lively experience to hear the comments of a dozen representative bird-watchers and opticians on Mr. Nicholson's views (p. 21). He condemns outright the non-prismatic pattern, chiefly on the ground t h a t one sees through it two intersecting circles instead of one. But t h a t is only the case when the instrument has no bending bar. If the non-prismatic glass has its defects, it has one merit : good illumination and, according to an expert optician, it distorts an approaching object less than the prismatic. Still, most will
Issue 8

Stay at the forefront of British birding by taking out a subscription to British Birds.

Subscribe Now