STUDIES OF MAMMALIAN LIFE HISTORIES 5 
RELATIONS OF MAMMALS AND PLANTS 
The influence of mammals on the distribution of plants is doubtless 
far more pervasive and important than has been realized. A signifi- 
cant intensive ecological study of the vegetation of a particular 
area has been made ‘by Farrow (6) in England. He writes (6, p. 
104): 
Apparently the presence of rabbits alone ig sufficient to change the potentially 
dominant plant on Cavenham Heath from Pinus sylvestris [Scotch pine] to 
Pteris aquilina [brake] through a large number of various stages. ... The 
passing of England from a forest period into a grassland period may of late 
have been accelerated by the influence of rabbits. 
With the modified conditions brought on in the United States by 
lumbering, grazing, and agriculture, the relations of the native 
mammals to forest and forage are often fundamentally changed. 
In some localities the maintenance of a sustained yield of forest and 
forage, or the successful operation of specialized and intensive agri- 
cultural enterprises, will ultimately depend in large measure on the 
solution of problems in the life history and control of various mam- 
mals. Unfortunately the significance of mammals (and of verte- 
brates generally) in these matters has been generally neglected, as a 
perusal of projects and bibliographies shows. To work out these 
relations is manifestly impossible without close attention to mam- 
malian life histories. 
LIFE HISTORY OF MAMMALS 
The suggestions (pp. 7-8) for studying the life history of mammals 
are divided so as to be applicable to the individual animal in its 
youth, maturity, and old age. Habits are known to change consider- 
ably at different stages of life, and such a division seems logical and 
justified by the demands for an adequate picture of the developing 
mammal. 
After the principal life-history stages of the mammal are studied, 
its structure and behavior are scrutinized more closely. Of special 
interest to the student of life habits are the form of the body as 
related to habits, special or noteworthy structural developments, and 
adaptations. Perhaps most of the work of the student of life his- 
tories, however, will be devoted to the behavior of the mammal, 
principally in nature, secondarily in the laboratory. Such points 
. as the disposition and temperament of the mammal, its senses, means 
of intercommunication, times of activity and leisure, movement, eat- 
ing and drinking, breeding, sanitation, flocking, hibernation, migra- 
tion, and adaptation or nonadaptation are the very essence of life- 
habits study. 
RELATIONS OF LOWER MAMMALS AND MAN 
Finally the relations of the lower mammals and man are con- 
sidered. The means of finding and counting mammals are referred 
to, and the direct and indirect relationships hinted at. These rela- 
tionships include the important effects of man’s activities on wild 
mammals, and, conversely, the effects of the mammalian activities on 
man’s interests. There is also suggested the possibility of unde- 
veloped mammalian resources, as of flesh for food and fur or hides 
for clothing. 
