Nesting instinct

Nesting behavior is an instinct in animals during reproduction where they prepare a place with optimal conditions to nurture their offspring. The nesting place provides protection against predators and competitors that mean to exploit or kill offspring. It also provides protection against the physical environment. Nest building is important in family structure and is therefore influenced by different mating behaviours and social settings. It is found in a variety of animals such as birds, fish, mammals, amphibians, and reptiles.

Nesting behavior is an instinct in animals during reproduction where they prepare a place with optimal conditions to nurture their offspring. The nesting place provides protection against predators and competitors that mean to exploit or kill offspring. It also provides protection against the physical environment. Nest building is important in family structure and is therefore influenced by different mating behaviours and social settings. It is found in a variety of animals such as birds, fish, mammals, amphibians, and reptiles.

In mammals

Female dogs may show signs of nesting behaviour about one week before they are due that include pacing and building a nest with items from around the house such as blankets, clothing, and stuffed animals. (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. Commercial whelping and queening boxes are available; however, children's wading pools (dogs) and plastic dishpans (cats) work just as well. Marsupials do not exhibit a nesting instinct per se, because the mother's pouch fulfills the function of housing the newborns. Nest building is performed in order to provide sufficient shelter and comfort to the arriving offspring. Threats, such as predators, that decrease the chance of survival will increase care of offspring.

Hormones and nesting behavior

Maternal nest-building is regulated by the hormonal actions of estradiol, progesterone, and prolactin. Given the importance of shelter to offspring survival and reproductive success, it is no wonder that a set of common hormonal signals has evolved. However, the exact timing and features of nest building vary among species, depending on endocrine and external factors. The initial drive to perform this behavior is stimulated internally via hormones, specifically a rise in prolactin levels. This increase is driven by an increase in prostaglandin and a decrease in progesterone. The second phase of nest building is driven by external stimuli, this phase is also known as the material-oriented phase. In this stage it is said that external stimuli such as the proper nest building materials must be present. Both internal and external stimuli must exist in conjunction with one another for nest building to commence. The cessation of the nest building is correlated with a rise in oxytocin which is the hormone responsible for the contraction of the uterus. Shortly after this, parturition will commence. In rabbits, nest building occurs towards the last third of pregnancy. The mother digs and builds a nest of straw and grass, which she lines with hair plucked from her body. This sequential motor pattern is produced by changes in estradiol, progesterone, and prolactin levels. Six to eight days pre-partum, high levels of estradiol and progesterone lead to a peak in digging behavior. Both estradiol and progesterone are produced and released by the ovaries. One to three days pre-partum, straw-carrying behavior is expressed as a function of decreasing progesterone levels, maintenance of high estradiol levels, and increasing prolactin levels. This release of prolactin (from the anterior pituitary) is likely caused by the increase in estrogen-to-progesterone ratio. One day pre-partum to four days post-partum, hair loosening and plucking occur as a result of low progesterone and high prolactin levels, together with a decrease in testosterone. In house mice and golden hamsters, nest-building takes place earlier, at the start or middle of pregnancy. For these species, nest-building coincides with high levels of estrogen and progestin. External factors also interact with hormones to influence maternal nest-building behavior. Pregnant rabbits that have been shaved will line their straw nest with available alternatives, such as male rabbit hair or synthetic hair. If given both straw and hair, mothers prefer straw during the straw-carrying period, and prefer hair during the nest-lining period. If given hair as the only material, shaved mothers collect the hair even when it is the straw-carrying period.

In fish

In sand goby (Pomatoschistus minutus) the males are the ones who build the nests. When males exhibit increased paternal care to eggs, they build nests with smaller entrances in comparison to males who provide less parental care. This helps prevent predators from entering the nest and consuming the offspring or developing eggs.

In insects

(Andrena fulva) nest entrance]] Nesting behavior is also present in many invertebrates. The best known example of nesting behavior in insects is that of the domestic honey bee. Most bees build nests. Solitary bees, unlike honey bees, make nests. However, solitary bees make individual nests for larvae and are not always in colonies. Solitary bees will burrow into the ground, dead wood and plants.

See also

Genetic memory Broodiness Parental brain Nest-building in primates

References

Text derived from https://en.wikipedia.org/w/index.php?oldid=1368892431 under CC BY-SA 4.0; modifications have been made.