Investigations of the immediate climatic environment of selected desert 

 maremals by Vorhies (1945) have proved highly illuminating in relation to their 

 ecology and physiology. In order to supplement observations with concrete 

 data, use was made of a number of instruments, including soil thermographs 

 and hygrothermographs, rain gauges, thermometers, and the psychrometer. Those 

 interested in the life histories of any of the burrowing mammals, especially, 

 should consult this paper. 



By means of careful trapping, Blair (1940), Spencer (1941), and others 

 have obtained important information regarding movements of Permnyscus and small 

 rodents generally. Recently Stickel (1946a emd 1946b), through an adroit 

 combination of live-trapping, marking, snap-trapping, and removal of Peromyscus 

 on tracts of known size, has shown that animals trapped on a one-acre tract in 

 the middle of a 17-acre area were those whose normal ranges overlapped or 

 closely approached the area. When these were removed from the area the animals 

 taken in the central acre were in general those whose normal ranges were at 

 successively greater distances. Mrs. Stickel has also emphasized some of the 

 shortcomings in the current use of snap-trap data for determining actual popu- 

 lation numbers. Her methods should apply widely, although differences in 

 habits, trappabillty, and density of various species may influence and sometimes 

 invalidate results. Unquestionably, experiments of this sort possess wide 

 significance in such fields as rodent control and wildlife management. 



Th\xB it is apparent that in the ever-increasing recognition of the mammal 

 as a member of the blotic community, modern field workers are acquiring a more 

 thoroughgoing appreciation of its role in the physiology of the community. This 

 must of necessity apply also to the other animals, but even more important, to 

 the plants. Jleld mammalogists should be familiar with such papers as those 

 of Phillips (1931) and Taylor (1935b), which help to give the background and 

 setting for all field studies of ecological life histories • 



BACKGROUND EATA 



Preparation for Work 



The study of mammalian life histories opens a field of activity for any 

 sincere student with an enthusiasm for closer acquaintance with wildlife. No 

 human being or no book, but Nature herself, is the supreme authority in natural 

 history. The beginner as well as the veteran investigator may make important 

 observations, although training in scientific method and technic and broad 

 experience are desirable for work on habits. At best, one can read all too 

 little in "Nature's infinite book of secrecy," 



Environment and Heredity 



In a very real sense the mammal is the product of its surroundings, which 

 on every side influences the individual, the community, and the species. Although 

 there have been prolonged, critical, and thoroughgoing studies of heredity, 

 similar investigations of the environment are for the most part lacking, so 

 that the exact role of environment in the evolution and life of mammals is 

 unknown. The numerous significant and interesting studies in genetics and 



