Introduction to the Study of Animal Populations

Abstract

Information about animal populations is sought for a variety of purposes; but the object of a study will largely determine the methods used and thus this must be clearly defined at the outset. Very broadly studies may be divided into extensive and intensive (Morris, 1960). Extensive studies are carried out over a large area and are normally concerned with the distribution of insect species or with the relation of insect pest population to crop damage or with the prediction of damage and the application of control measures (e.g. Kaelin & Auer, 1954; Strickland, 1961; Chiang et al, 1961; National Academy of Sciences, 1969). A particular area will be sampled once or at the most a few times during the season, and emphasis will normally be placed on a particular developmental stage of the insect. The timing of such sampling is obviously of critical importance: it must be appropriate in relation to the phenology of the chosen stage (Morris & Bennett, 1967). Such studies will produce considerable information about the pattern of population level over a large area or in successive years, and it is often possible to relate the level of the population to certain edaphic or climatic factors (Kaelin & Auer, 1954; Chiang et al., 1961).