Why might there be a competitive advantage to having a different flight initiation distance when a bird is incubating eggs

The birds can perceive any kind of danger which can harm the eggs after laying.

Explanation:

The birds show response towards the other stimulus around them like weather conditions like excessive heat and rain and predators. Also they can sense the danger of damage to eggs by fellow members of the species. The distance at which the birds fly from the danger is the flight initiation distance. It is the separation distance from any kind of danger or disturbance and birds cross this distance before incubating their eggs. This is an competitive advantage with that of other members of the species as the bird will able to give birth to new ones and its population will increase in number, so the chances of reproduction and survival increases in this case.