Why can the first-hatched falconiform chick have an advantage over younger siblings?

The first-hatched falconiform chick gains a significant advantage over its younger siblings primarily due to the order in which eggs are laid and subsequently hatch. Because eggs are laid at intervals of two to four days, the first chick to hatch has a head start in growth and development.1

By the time the final egg in a clutch has hatched, the first-hatched chick may have already tripled its body weight. This size disparity allows the older, larger chick to dominate its younger siblings through direct competition for food. In some instances, this advantage is so pronounced that the first-hatched chick may kill its younger siblings, either through direct aggression or by outcompeting them for the resources provided by the parents.1