Social Factors in Adult Reproduction: Introduction

Abstract

The social environment surrounding a mammal can have major effects on its reproductive ability. The elements which constitute this environment have a more intense action when individuals are living at high densities, although there are many dangers inherent in using density as a measure of the action of these social elements in a group of mammals (see page 24). The reproductive response to a detrimental social situation can range from a mere reduction in the live weight at birth, with little effect on survival of the neonate, to a cessation of oestrous cycles so that breeding completely stops. This range of responses overlaps the classification of breeding phenomena, which are used in this book to document responses to other environmental variables. However, if for reasons of consistency the onset or cessation of breeding was the only parameter considered here, and the effect of social factors on other parameters such as the proportion of females pregnant, the degree of prenatal mortality and litter size (to name a few), were relegated to another section on social factors and pregnancy the result would be an arbitrary and artificial division. The majority of papers considering the effects of social factors on reproduction document the various levels of reproductive response within a continuum, so that they would need under this system to be repeatedly referred to under separate sections based on subdivisions of the possible range of responses. For this reason the following chapters will consider the effects of social factors on reproduction from oestrus to weaning. It is realized that much the same line of reasoning could be logically applied to the rest of the book, but experience in organizing the material available has shown that actually the papers describing the action of factors such as climate, nutrition, etc., do fall more naturally into the separate units which make up the various stages of the reproductive processes.