Great blue herons breed once a year — from March to May in northern parts of their range, and from November to April in southern parts of their range. They lay an average of three to five eggs per season, which hatch after approximately 30 days. Juveniles will fledge after about two months, and reach reproductive maturity at about 22 months.

These patient predators stalk a wide variety of wetland prey near ponds, streams, lakes, rivers, marshes, swamps, and coastlines, spearing and swallowing everything whole, from fish to frogs to snakes to rodents. Although they typically hunt solo, they often nest in trees together, in groups called rookeries.