B O O K

dependent factors influencing either the repro- ductive rate or the mortality; the former must be smaller or the latter greater at high densities than at low.

Evidence is provided for the view that clutch or litter size has been adapted in each species so that the maximum number of young are reared: in the Swift, for instance, large clutches may produce fewer young than small clutches in bad weather because the parent cannot provide enough food. Fecundity falls slightly with population density in some species, but this is probably not an important effect in birds, though it may be in some other groups (e.g., deer).

Although density-dependent mortality factors must be important in nature there is little direct evidence about their action. The relative importance of food shortage, disease a n d predators varies between different groups of animals: amongst birds food is probably the most important.

Dr. Lack then applies these basic principles to the study of population cycles and irruptions, and to the significance of migration, gregarious- ness and dispersion. The greater part of the discussion and of the extensive bibliography (e. 1,000 references) is concerned with birds, but the more important literature relating to other groups is sumrnarised. The author describes his book not as a textbook, but a signpost, and his original views on many pre- viously controversial issues will certainly point the Way for further advances. The discussion is always vivid a nd stimulating, and ecologists will certainly come to regard the book as a classic. It is important that it should also be read by students of animal behaviour, for ecology and behaviour study cannot be divorced: either alone is ultimately non-viable,

R.A.H.

The Distemper Complex. By LEON F. WHITNEY and GEORGE D. WHITNEY. Orange, Connecti- cut: Practical Science Publishing Co. 1953. Pp, v i i i + 219. $ 5.00. This work has arisen out of the senior author's

Canine Distemper and the Diseases of the Distemper Complex, which in turn was based upon an elaboration of a series of articles con- tributed to a dog magazine. It is meritable therefore, that despite its 1,500 references this "History, symptoms, diagnosis, pathology and treatment of eleven of the diseases which

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comprise the distemper complex" differs con- siderably in style from a conventional veterin- ary textbook, consisting in many parts of some- what pithy abstracts. It nevertheless represents a useful aggregation of information and as such is likely to be widely read by veterinarians.

A critical discussion of the subject matter is clearly out of place in this journal, but one lesson to be learned is the importance of close clinical observation. Readers of the Bulletin of Animal Behaviour will recall the pleas that were made for the application of behavioural studies to clinical veterinary science, and any study of the group that Whitney and Whitney have discussed collectively must support that attitude.

A,N.W.

The Seals and the Curragh. By R. M. LOCKLEY. London: J. M. Dent. 1954. Pp. vii + 149. 15s. The sub-title of this popular work is "Intro-

ducing the Natural History of the Grey Seal in the North Atlantic," and it is clear from the text, which is accompanied by several good photographs, that the author has many original observations that are worth putting on scientific record alongside the material acknowledged under "Bibliographical Notes" on p. 143. Unfortunately for the serious reader, however, this volume is clearly aimed at a much wider public and is therefore a mixture of record and narrative. It is sincerely to be hoped that a scientific paper will follow.

A.N.W.

Bird Pageant. Field studies of some East Anglian breeding birds. By A. W. P. ROBERTSON. London: Blatchworth. 1954. Pp. 192. 21s. This book on the birds of East Anglia, seen

against evocative descriptionls of their habitats, is an example of amateur natural history at its best. It surveys the characteristic birds of the area, all from personal observation, and deals in detail with the Montague's Harrier, Cross- bill Woodlark, Stone Curlew, Hawfinch, Wry- neck, Corn Bunting and Moorhen. There are many new and interesting facts about their behaviour, carefully recorded, yet unencumb- ered by the boring (to anyone but the specialist) lists of vital statistics that sometimes mar works of this kind. Of the two rather incompatible tendencies, to observe the whole behaviour, and to count things, Commander Robertson has advisedly concentrated on the former.

P.M.