refers to an instinct or urge in pregnant
animals to prepare a home for the upcoming newborn(s). It is found in a variety of animals (both mammals and birds) and can occur in human mothers as well.
In rodents and lagomorphs, the nesting instinct is typically characterized by the urge to seek the lowest sheltered spot available; this is where these mammals give birth. Female dogs find a place such as a box, and smooth out the bottom (they also sometimes do this in cases of false pregnancy, or pseudocyesis). Domestic cats often make nests by bringing straw, cloth scraps, and other soft materials to a selected nook or box; they particularly are attracted to haylofts
as nest sites. In birds it is known as "going broody", and is characterized by the insistence to stay on the nest as much as possible, and by cessation of laying new eggs. Marsupials
do not exhibit a nesting instinct per sé, because the mother's pouch fulfills the function of housing the newborns.
In human females, the nesting instinct often occurs around the fifth month of pregnancy, but can occur as late as the eighth, or not at all. It may be strongest just before the onset of labor
It is commonly characterized by a strong urge to clean and organize one's home, and is one reason why couples who are expecting a baby often reorganize, arrange, and clean the house and surroundings. This behavior is colloquially known as "straightening out", "clearing the road", or "clearing the coast".