Green Heron
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Common name:
Green Heron
Class: Aves
Order: Pelicaniformes
Family: Ardeidae
Genus: Butorides
Species: Butorides virescens |
photo Ivan
Andrijevic |
Taxonomy/Description
The Green Heron
is an Ardeid which groups it together with other herons. Green Herons are
small and stocky, with legs that are relatively short,
compared to other herons. Their body length ranges from
41 to 46 centimeters. Adults have a glossy
greenish-black cap and back, wings that are black
grading into green and/or blue on the edges, and a grey
underbelly. The bill of a Green Heron is dark with a
long, sharp point and the legs are orange. Female adults
tend to be smaller, with duller and lighter plumage than
that seen in males, particularly in the breeding season.
The coloration of immature herons is
different. The neck and chest are striped with white and
shades of brown. Their backs are also brown with white
and beige spots. The coloration of both immature and
adult birds is quite cryptic in dense vegetation where
they sometimes live.
photo Ivan Andrijevic
Habitat/Diet
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 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.
During non-breeding season individuals are found in Mexico and
Central America, Texas, southern New Mexico and Arizona,
and the Caribbean islands.
photo Ivan Andrijevic
Green Herons are carnivorous, mainly
eating fish and invertebrates. In addition, they are
foragers with a broad prey base, depending on the
availability of species present. They exploit
superabundant food resources, such as breeding frogs.
The Green Heron invertebrate diet includes leeches,
earthworms, dragonflies, damselflies, waterbugs,
grasshoppers, and crayfish. They also eat vertebrates
such as fish,
rodents, lizards, frogs, tadpoles, and snakes. The
heavy bill of a green heron enables them to capture
large prey.
Feeding can take place at any time, day or
night. The most common feeding technique used by Green Herons
is to stand in a crouched position, horizontal to the
water surface, with neck and head retracted and then
striking out to impale their prey. 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. Green Herons stand motionless near the bait until
a small fish or other animal approaches and then grab
the prey.
Behavior/Reproduction
Green Herons are seasonally monogamous, they chose a
different mate each season. Their display for
mates begin with flying around
breeding sites with skow calls. Next they
will engage in pursuit flight,
circle flight and forward displays are used.
The
stretch display is also used in courtship displays and 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.
Males perform this stretch display
before a female is allowed to enter the eventual nest
area. The female then performs a less intense stretch
silently after the male, which confirms the pair-bond. After the last egg is
laid, mating ceases, and incubation lasts for 19-21
days. Fledging occurs when chicks are 16 to 17 days
old, and independence is gained between 30 and 35 days.
Nesting takes place in forest and swamp
patches, over water or in plants near water. Nesting
pairs normally nest alone, but loose aggregations of
mated pairs can form.
Green Herons are shy birds so are
rarely observed, although they may be quite common.
They are active during the day, and have a
characteristic slow, deliberate walk and in flight they
have slow and steady wingbeats. Green Herons may also
swim on occasion in pursuit of prey, are territorial,
and will aggressively defend both foraging and nesting
territories from conspecifics.
Where to see them in WNY
One good place to find the
Green Heron is in Iroquois National Wildlife Refuge as
well as Forest Lawn Cemetary, Tifft Preserve and other
areas that include small water bodies Green Herons
commonly use for foraging during the summer.
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