Introduction

Canids are frequently cited as being unusual among mammals for their tendency toward monogamy (Kleiman 1977). Yet, there are other features of their reproductive biology that are not typical of most mammalian species but that are important to understanding their unique reproductive systems. These features include monestrum, obligate pseudopregnancy in adult females that fail to conceive, incorporation of postpubertal offspring into the social unit, behavioral suppression of reproduction in subordinates so that only the dominant pair produces young, possible inbreeding avoidance, the production of altricial young, and parental care by other group members including adult males. This chapter will discuss the unique interplay of social organization and physiology that appears to have evolved in canids that may enhance both social accord and reproductive success.

The Basic Canid Social System

The primary social unit of canids is the male–female mated pair, with a strong tendency toward long-term allegiance, often for life (see Kleiman & Eisenberg 1973; Macdonald 1983; Moehlman 1989 for review). Even for species such as many of the foxes in which pairs separate during the nonbreeding season, the same animals are likely to be found together in successive years. Larger social groups typically are composed of the mated pair and young of the year or of previous years. Exceptions to the apparent rule of monogamy have been reported for the red, Vulpes vulpes (Macdonald 1983; Zabel & Taggart 1989) and kit, V. macrotis (Egoscue 1962) foxes.