Avian development refers to the growth and maturation processes of birds, starting from fertilization to adulthood. It involves several stages, including the formation of the embryo within the egg, hatching, and the subsequent growth phases. Key factors influencing avian development include genetics, environmental conditions, and parental care. During the incubation period, the embryo develops vital organs and structures, such as feathers and wings. After hatching, chicks undergo rapid growth, learning essential survival skills like foraging and flying. The duration and specifics of these stages can vary significantly among different species, such as sparrows and eagles.