Bird of the Month: Green Heron
By Andy McCormick
PC: Mick Thompson (Green Heron)
Scientific Name: Botarus lentiginosus
Length 18-25 in
Wingspan 26 in
Weight 7 oz
AOU Band code GRHE
Green Herons belong to the genus Butorides, which refers to being “bittern-like” and derives from Butor, an Old English word for bittern. They are the species virescens, from the Latin viresco, to become green (Holloway, 2003). In field guides of the 1970s and 1980s these birds were grouped with the Striated Heron of Central and South America and called the Green-backed Heron (Butorides striates). However they were separated out again in the 1990s. The juvenile birds are heavily streaked on the face, neck and breast. The adults are similar and have a dark greenish-black crown and the back and wings are an iridescent green mixed with grey-blue. The back and sides of the adult’s neck is deep chestnut. The bill is mixed yellow and black and the legs are yellow. In breeding plumage the bill will become all black and the legs will flush bright orange. Overall, it is a small, stocky heron.
Primarily found in eastern North American, Green Herons are also found in the American southwest and along the Pacific coast. The discovery of a Green Heron on a field trip is often met with excitement and surprise since they tend to be a bit secretive. These birds are often solitary and can be found along the edges of ponds, marshes, sloughs, and slow moving streams especially if there are grasses, shrubs and trees around. They like to be close to cover and can often be found crouched in branches along or overhanging the water. Scanning with binoculars along the edges of waterways can help a birder pick one out of dark areas. They feed primarily on small fish, frogs, tadpoles, some crustaceans, and sometimes insects. They are skillful fishers and are one of our few birds that use tools to forage. They will drop a leaf, feather or other small object onto the surface of the water as “bait” and then grab fish that come to investigate.
Green Herons migrate to the very south of the United States during October, but there can be vagrants into the early winter. They return to their Northwest breeding area in May. The male initiates nest building with twigs and once paired will bring material to the female. Four to five pale blue-green eggs are incubated for about 20 days. The first eggs get a head start, resulting in asynchronous hatching and chicks of different sizes (Sibley, 2001). The parents provide food by regurgitating into the mouths of the young and often the smallest chick is outcompeted and does not survive. Unlike other herons whose populations are suffering due to wetland drainage and urbanization, Green Herons have a stable population and may be expanding their range in our area. They are colorful and unique and we are fortunate to have them as part of the Pacific Northwest avifauna.