The incubation period for great egret eggs is 23 - 26 days. Eggs hatch asynchronously over a period of several days. The first chick to hatch thus becomes the most experienced at food handling, and quickly becomes the most experienced aggressor toward its siblings. As a result, nestmates have varied growth rates, with the first chick generally growing the fastest. Great egrets are eurythermal .
Great egrets are heterotrophs .
They are opportunistic predators with a wide variety of prey species including fish, crustaceans, amphibians, small mammals, insects and reptiles. Great egrets eat more large fish of more different species than do other wading birds. They thus have low dietary overlap with other heron and egret species. This can be partially attributed to their large size, which contributes to their ability to forage in deeper waters where they encounter more large fish than other species do. Another reason for lower dietary overlap with other wading birds is that great egrets are capable of adjusting their diets based on changing environmental conditions.