Butorides is a genus of small herons. It contains three similar species, the Green Heron or Green-backed Heron, Butorides virescens, the Dwarf Bittern (Butorides sturmii), and the Striated Heron, Butorides striatus. A fossil species, Butorides validipes, is known from the Early Pleistocene of Florida. Adults of both extant species are about 44 cm long, and have a blue-black back and wings, a black cap and short yellow legs. Juveniles are browner above and streaked below, and have greenish-yellow legs. The species have different underpart colours, chestnut with a white line down the front in Green Heron, and white or grey in Striated. Both breed in small wetlands on a platform of sticks often in shrubs or trees, sometimes on the ground. Butorides herons stand still at the water’s edge and wait to ambush prey. They mainly eat small fish, frogs and aquatic insects. They sometimes drop food on the water’s surface to attract fish.
Coloration of immature herons is different. The neck and chest are striped with white and shades of brown. The back is also brown with white and beige spots. The coloration of immature and adult birds is quite cryptic in dense vegetation.
Listen to the sound of Green Heron
Copyright remark: Most sounds derived from xeno-canto
|wingspan min.:||62||cm||wingspan max.:||65||cm|
|size min.:||42||cm||size max.:||45||cm|
|incubation min.:||19||days||incubation max.:||21||days|
|fledging min.:||30||days||fledging max.:||21||days|
Nonaerial displays are interspersed with display flights. In the Snap Display, the male perches, then points body, head and neck down until bill tip is at or below the level of his feet and then snaps his mandibles together, producing a click while also erecting his feathers. The Stretch Display involves the male pointing his bill straight up, stretching his neck, and then bending it backwards until the head almost touches its back with interscapular plumes erect and fanned. In this posture, he sways his neck and head from side to side with crest, breast, and flank feathers sleeked back, eyes bulging, and iris possibly turning from yellow to deep orange while emitting an aaroo-aaroo sound.
After the last egg is laid, copulations cease and incubation persists for 19-21 days. A normal clutch is 2 to 4 eggs, laid in 2-day intervals. Fledging occurs when chicks are 16 to 17 days old, and independence is gained between 30 and 35 days. Both adults feed and brood chicks, though at less frequent intervals as the chicks become more independent.
Their heavy bill enables them to capture large prey. Feeding can take place at any time, day or night. Typically, prey is captured with a darting stroke of the head and neck, lunging the body towards the victim and either grabbing or impaling the prey.
Among North American diurnal herons, green herons exhibit the fewest kinds of feeding behaviors. They are known to use 15 of the 36 heron feeding behaviors. The most common feeding technique is to stand in a crouched position, horizontal to the water surface, with neck and head retracted. They stand still for long periods of time before changing sites. Standing is often interspersed with slow walking in a crouched posture in the water or bordering vegetation. Herons use their feet to cause potential prey to move and then capture them. They may also dive from perches head first into deep water, becoming submerged, although this isn’t a very efficient method. The greatest capture success is in shallowest water (0-10 cm) and the poorest success is in deeper water (20-30 cm).
Green herons are one of the few tool-using birds. They use a variety of baits and lures, such as crusts of bread, mayflies, and feathers. They then put the bait on the water surface and wait for prey to attack the bait. They stand motionless near the bait until a small fish or other animal approaches and then grab the prey. Success rates have been highest when live bait was used versus inanimate or dead bait. Juvenile herons are not as adept at baiting prey.
Video Green Heron
Green herons have a wide range in North America, but are generally found near wetlands. They occur as far north as southern Canada and as far south as northern South America. They are found throughout the eastern United States as far west as North Dakota and the Great Plains states, although some sedentary populations occur on the west coast. During the breeding season they are found primarily in the eastern United States, with some populations in the Pacific Northwest as well. Non-breeding individuals are found in Mexico and Central America, Texas, southern New Mexico and Arizona, and the Caribbean islands. Small vagrant populations winter in Hawaii and the United Kingdom. Some populations migrate and others are sedentary populations. Sedentary populations occur along the east and west coasts of the United States and Central America. Most populations in North America, however, are migratory. After breeding they disperse southwards, in mid-September. Spring migration occurs from March to April, an earlier arrival than most other herons.
Only the northernmost populations migrate, and in winter end up along the Gulf coast and southern ocean coasts and into Mexico and Central America