: Breeds. May-Aug around salt water bays and marshes, often at some distance from their nest sites. Bass Harbor Marsh and the mud flats off Thompson's Island are favored spots. Breeds in a few widely scattered (small ??) colonies, often on islands. They normally occur singly or more rarely, when drawn by an food source, in very small groups.
: and around water late Mar-late Apr and again mid Sep-early Nov with from mid Mar and to late Nov. Sometimes, primarily in fall, seen far in small migrating flocks.
: Dec-early Jan, mostly in warm winters. mid Jan-early Mar.
Miscellany: Great Blue Heron is a formidable predator and can survive cold weather by augmenting its normal diet of fish and other aquatic creatures with birds and small mammals, the latter often caught well away from water.
You can learn more about Great Blue Herons and see images here.
Last Reviewed: June 11th, 2026