Birds

Birds serve as a counterexample to any simple equation between female biology and exclusive maternal care. Simone de Beauvoir describes variation among species: females commonly incubate eggs and care for young, but fathers may help build nests, protect and feed offspring, or assume much of their care. The comparison supports her broader argument that biological facts acquire significance through the conditions in which they operate; they do not by themselves settle how labor must be divided among human beings.

Reproduction and parental care

In birds, the egg develops relatively slowly inside the female and is comparatively large and difficult to expel. These features make the mother’s connection to it closer than the father’s, whose role in fertilization is brief. The female therefore usually sits on the egg and subsequently cares for the young. Yet this common pattern is not universal: males frequently participate in nest construction and in protecting and feeding offspring, and, in rare cases such as the passerine example given in the book, the male incubates the eggs and raises the young.

Shared care and its limits

Pigeons offer another instance of parental contribution: both male and female secrete a substance in the crop and feed it to their fledglings. Across the examples, the account distinguishes the female’s closer biological connection to the egg from the possibility of substantial paternal care. It also notes a condition associated with fathers’ nurturing role: spermatogenesis stops during the period devoted to offspring. In this discussion, care is not merely an extension of ongoing reproductive activity; it occupies time that is no longer being used to produce new life.

Place in the argument

The bird examples sit within a wider comparison of reproduction across animal life. They complicate a strict separation between a female who maintains life and a male who creates or acts: parental responsibilities can be shared, and in some cases the father takes the more sustained caring role. For Beauvoir, such observations do not turn animal behavior into a prescription for human society. Her larger argument is that human life is historical and social, so biological characteristics matter according to their practical and institutional context rather than functioning as an unalterable destiny.

From biological variation to social conditions

The comparison informs the book’s discussion of the burdens women face when reproductive responsibilities are combined with work. Beauvoir argues that the consequences of maternity depend on social arrangements: repeated pregnancies and the expectation that women care for children without assistance can make those burdens overwhelming, whereas reproductive choice and social support can make them lighter and compatible with work. Birds’ varied patterns of care help establish the limited point that reproductive roles are not identical across species; the human question, however, concerns the social distribution of responsibility and the conditions under which women can participate in public life.