Final answer:
The behavior of a broody hen lying on eggs until they hatch is called a Fixed Action Pattern, an innate behavior integral to ensuring the eggs are incubated properly to maximize the chances of successful hatching.
Step-by-step explanation:
The behavior of a broody hen sitting on her eggs until they hatch can be categorized as a Fixed Action Pattern. This is a type of innate behavior that is hardwired into an animal's biology and occurs in response to a specific trigger or set of triggers. In the case of the broody hen, this behavior ensures that the eggs are kept at a necessary, constant temperature and are protected until they hatch, which directly contributes to the mother’s fitness.
In contrast to learned behaviors, which can vary widely within a species, innate behaviors like broody incubation and egg rolling in graylag geese are consistent among individuals of a species. For example, when a graylag goose's egg rolls out of the nest, the innate response is to use its bill to return the egg to the nest. Similarly, broody hens do not require training to sit on their eggs; it is an automatic behavior designed to optimize the chances of offspring survival. This behavior is important because it maximizes the potential for the embryos within the eggs to develop successfully and eventually hatch.
Incubation is not limited to females in birds; often both males and females share in the nesting and incubation duties, contributing to parental care that can increase the chances of successful hatching and rearing of offspring. This type of care, including behaviors such as territory defense, incubation, and feeding of chicks, showcases the importance of parental investment in avian species.