How are sparrow eggs fertilized?

Sparrow eggs are fertilized internally when a male bird mates with a female. During copulation, the male transfers sperm to the female's cloaca, where it can fertilize the eggs as they are released from the ovaries. After fertilization, the eggs are formed and coated with protective layers before being laid by the female. This process typically occurs in the nesting season, ensuring the eggs are laid in suitable conditions for development.